diff options
Diffstat (limited to 'compiler/rustc_middle/src')
101 files changed, 46029 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs new file mode 100644 index 00000000000..f6570cc95d2 --- /dev/null +++ b/compiler/rustc_middle/src/arena.rs @@ -0,0 +1,110 @@ +/// This declares a list of types which can be allocated by `Arena`. +/// +/// The `few` modifier will cause allocation to use the shared arena and recording the destructor. +/// This is faster and more memory efficient if there's only a few allocations of the type. +/// Leaving `few` out will cause the type to get its own dedicated `TypedArena` which is +/// faster and more memory efficient if there is lots of allocations. +/// +/// Specifying the `decode` modifier will add decode impls for `&T` and `&[T]` where `T` is the type +/// listed. These impls will appear in the implement_ty_decoder! macro. +#[macro_export] +macro_rules! arena_types { + ($macro:path, $args:tt, $tcx:lifetime) => ( + $macro!($args, [ + [] layouts: rustc_target::abi::Layout, + // AdtDef are interned and compared by address + [] adt_def: rustc_middle::ty::AdtDef, + [] steal_mir: rustc_middle::ty::steal::Steal<rustc_middle::mir::Body<$tcx>>, + [decode] mir: rustc_middle::mir::Body<$tcx>, + [] steal_promoted: + rustc_middle::ty::steal::Steal< + rustc_index::vec::IndexVec< + rustc_middle::mir::Promoted, + rustc_middle::mir::Body<$tcx> + > + >, + [decode] promoted: + rustc_index::vec::IndexVec< + rustc_middle::mir::Promoted, + rustc_middle::mir::Body<$tcx> + >, + [decode] typeck_results: rustc_middle::ty::TypeckResults<$tcx>, + [decode] borrowck_result: + rustc_middle::mir::BorrowCheckResult<$tcx>, + [decode] unsafety_check_result: rustc_middle::mir::UnsafetyCheckResult, + [] const_allocs: rustc_middle::mir::interpret::Allocation, + // Required for the incremental on-disk cache + [few] mir_keys: rustc_hir::def_id::DefIdSet, + [] region_scope_tree: rustc_middle::middle::region::ScopeTree, + [] dropck_outlives: + rustc_middle::infer::canonical::Canonical<'tcx, + rustc_middle::infer::canonical::QueryResponse<'tcx, + rustc_middle::traits::query::DropckOutlivesResult<'tcx> + > + >, + [] normalize_projection_ty: + rustc_middle::infer::canonical::Canonical<'tcx, + rustc_middle::infer::canonical::QueryResponse<'tcx, + rustc_middle::traits::query::NormalizationResult<'tcx> + > + >, + [] implied_outlives_bounds: + rustc_middle::infer::canonical::Canonical<'tcx, + rustc_middle::infer::canonical::QueryResponse<'tcx, + Vec<rustc_middle::traits::query::OutlivesBound<'tcx>> + > + >, + [] type_op_subtype: + rustc_middle::infer::canonical::Canonical<'tcx, + rustc_middle::infer::canonical::QueryResponse<'tcx, ()> + >, + [] type_op_normalize_poly_fn_sig: + rustc_middle::infer::canonical::Canonical<'tcx, + rustc_middle::infer::canonical::QueryResponse<'tcx, rustc_middle::ty::PolyFnSig<'tcx>> + >, + [] type_op_normalize_fn_sig: + rustc_middle::infer::canonical::Canonical<'tcx, + rustc_middle::infer::canonical::QueryResponse<'tcx, rustc_middle::ty::FnSig<'tcx>> + >, + [] type_op_normalize_predicate: + rustc_middle::infer::canonical::Canonical<'tcx, + rustc_middle::infer::canonical::QueryResponse<'tcx, rustc_middle::ty::Predicate<'tcx>> + >, + [] type_op_normalize_ty: + rustc_middle::infer::canonical::Canonical<'tcx, + rustc_middle::infer::canonical::QueryResponse<'tcx, rustc_middle::ty::Ty<'tcx>> + >, + [few] all_traits: Vec<rustc_hir::def_id::DefId>, + [few] privacy_access_levels: rustc_middle::middle::privacy::AccessLevels, + [few] foreign_module: rustc_middle::middle::cstore::ForeignModule, + [few] foreign_modules: Vec<rustc_middle::middle::cstore::ForeignModule>, + [] upvars_mentioned: rustc_data_structures::fx::FxIndexMap<rustc_hir::HirId, rustc_hir::Upvar>, + [] object_safety_violations: rustc_middle::traits::ObjectSafetyViolation, + [] codegen_unit: rustc_middle::mir::mono::CodegenUnit<$tcx>, + [] attribute: rustc_ast::Attribute, + [] name_set: rustc_data_structures::fx::FxHashSet<rustc_span::symbol::Symbol>, + [] hir_id_set: rustc_hir::HirIdSet, + + // Interned types + [] tys: rustc_middle::ty::TyS<$tcx>, + [] predicates: rustc_middle::ty::PredicateInner<$tcx>, + + // HIR query types + [few] indexed_hir: rustc_middle::hir::map::IndexedHir<$tcx>, + [few] hir_definitions: rustc_hir::definitions::Definitions, + [] hir_owner: rustc_middle::hir::Owner<$tcx>, + [] hir_owner_nodes: rustc_middle::hir::OwnerNodes<$tcx>, + + // Note that this deliberately duplicates items in the `rustc_hir::arena`, + // since we need to allocate this type on both the `rustc_hir` arena + // (during lowering) and the `librustc_middle` arena (for decoding MIR) + [decode] asm_template: rustc_ast::InlineAsmTemplatePiece, + + // This is used to decode the &'tcx [Span] for InlineAsm's line_spans. + [decode] span: rustc_span::Span, + [decode] used_trait_imports: rustc_data_structures::fx::FxHashSet<rustc_hir::def_id::LocalDefId>, + ], $tcx); + ) +} + +arena_types!(rustc_arena::declare_arena, [], 'tcx); diff --git a/compiler/rustc_middle/src/dep_graph/dep_node.rs b/compiler/rustc_middle/src/dep_graph/dep_node.rs new file mode 100644 index 00000000000..a61b9af9bac --- /dev/null +++ b/compiler/rustc_middle/src/dep_graph/dep_node.rs @@ -0,0 +1,407 @@ +//! This module defines the `DepNode` type which the compiler uses to represent +//! nodes in the dependency graph. +//! +//! A `DepNode` consists of a `DepKind` (which +//! specifies the kind of thing it represents, like a piece of HIR, MIR, etc) +//! and a `Fingerprint`, a 128-bit hash value the exact meaning of which +//! depends on the node's `DepKind`. Together, the kind and the fingerprint +//! fully identify a dependency node, even across multiple compilation sessions. +//! In other words, the value of the fingerprint does not depend on anything +//! that is specific to a given compilation session, like an unpredictable +//! interning key (e.g., NodeId, DefId, Symbol) or the numeric value of a +//! pointer. The concept behind this could be compared to how git commit hashes +//! uniquely identify a given commit and has a few advantages: +//! +//! * A `DepNode` can simply be serialized to disk and loaded in another session +//! without the need to do any "rebasing" (like we have to do for Spans and +//! NodeIds) or "retracing" (like we had to do for `DefId` in earlier +//! implementations of the dependency graph). +//! * A `Fingerprint` is just a bunch of bits, which allows `DepNode` to +//! implement `Copy`, `Sync`, `Send`, `Freeze`, etc. +//! * Since we just have a bit pattern, `DepNode` can be mapped from disk into +//! memory without any post-processing (e.g., "abomination-style" pointer +//! reconstruction). +//! * Because a `DepNode` is self-contained, we can instantiate `DepNodes` that +//! refer to things that do not exist anymore. In previous implementations +//! `DepNode` contained a `DefId`. A `DepNode` referring to something that +//! had been removed between the previous and the current compilation session +//! could not be instantiated because the current compilation session +//! contained no `DefId` for thing that had been removed. +//! +//! `DepNode` definition happens in the `define_dep_nodes!()` macro. This macro +//! defines the `DepKind` enum and a corresponding `DepConstructor` enum. The +//! `DepConstructor` enum links a `DepKind` to the parameters that are needed at +//! runtime in order to construct a valid `DepNode` fingerprint. +//! +//! Because the macro sees what parameters a given `DepKind` requires, it can +//! "infer" some properties for each kind of `DepNode`: +//! +//! * Whether a `DepNode` of a given kind has any parameters at all. Some +//! `DepNode`s could represent global concepts with only one value. +//! * Whether it is possible, in principle, to reconstruct a query key from a +//! given `DepNode`. Many `DepKind`s only require a single `DefId` parameter, +//! in which case it is possible to map the node's fingerprint back to the +//! `DefId` it was computed from. In other cases, too much information gets +//! lost during fingerprint computation. +//! +//! The `DepConstructor` enum, together with `DepNode::new()`, ensures that only +//! valid `DepNode` instances can be constructed. For example, the API does not +//! allow for constructing parameterless `DepNode`s with anything other +//! than a zeroed out fingerprint. More generally speaking, it relieves the +//! user of the `DepNode` API of having to know how to compute the expected +//! fingerprint for a given set of node parameters. + +use crate::mir::interpret::{GlobalId, LitToConstInput}; +use crate::traits; +use crate::traits::query::{ + CanonicalPredicateGoal, CanonicalProjectionGoal, CanonicalTyGoal, + CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal, + CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpSubtypeGoal, +}; +use crate::ty::subst::{GenericArg, SubstsRef}; +use crate::ty::{self, ParamEnvAnd, Ty, TyCtxt}; + +use rustc_data_structures::fingerprint::Fingerprint; +use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX}; +use rustc_hir::definitions::DefPathHash; +use rustc_hir::HirId; +use rustc_span::symbol::Symbol; +use std::hash::Hash; + +pub use rustc_query_system::dep_graph::{DepContext, DepNodeParams}; + +// erase!() just makes tokens go away. It's used to specify which macro argument +// is repeated (i.e., which sub-expression of the macro we are in) but don't need +// to actually use any of the arguments. +macro_rules! erase { + ($x:tt) => {{}}; +} + +macro_rules! is_anon_attr { + (anon) => { + true + }; + ($attr:ident) => { + false + }; +} + +macro_rules! is_eval_always_attr { + (eval_always) => { + true + }; + ($attr:ident) => { + false + }; +} + +macro_rules! contains_anon_attr { + ($($attr:ident $(($($attr_args:tt)*))* ),*) => ({$(is_anon_attr!($attr) | )* false}); +} + +macro_rules! contains_eval_always_attr { + ($($attr:ident $(($($attr_args:tt)*))* ),*) => ({$(is_eval_always_attr!($attr) | )* false}); +} + +macro_rules! define_dep_nodes { + (<$tcx:tt> + $( + [$($attrs:tt)*] + $variant:ident $(( $tuple_arg_ty:ty $(,)? ))* + ,)* + ) => ( + #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)] + #[allow(non_camel_case_types)] + pub enum DepKind { + $($variant),* + } + + impl DepKind { + #[allow(unreachable_code)] + pub fn can_reconstruct_query_key<$tcx>(&self) -> bool { + match *self { + $( + DepKind :: $variant => { + if contains_anon_attr!($($attrs)*) { + return false; + } + + // tuple args + $({ + return <$tuple_arg_ty as DepNodeParams<TyCtxt<'_>>> + ::can_reconstruct_query_key(); + })* + + true + } + )* + } + } + + pub fn is_anon(&self) -> bool { + match *self { + $( + DepKind :: $variant => { contains_anon_attr!($($attrs)*) } + )* + } + } + + pub fn is_eval_always(&self) -> bool { + match *self { + $( + DepKind :: $variant => { contains_eval_always_attr!($($attrs)*) } + )* + } + } + + #[allow(unreachable_code)] + pub fn has_params(&self) -> bool { + match *self { + $( + DepKind :: $variant => { + // tuple args + $({ + erase!($tuple_arg_ty); + return true; + })* + + false + } + )* + } + } + } + + pub struct DepConstructor; + + #[allow(non_camel_case_types)] + impl DepConstructor { + $( + #[inline(always)] + #[allow(unreachable_code, non_snake_case)] + pub fn $variant(_tcx: TyCtxt<'_>, $(arg: $tuple_arg_ty)*) -> DepNode { + // tuple args + $({ + erase!($tuple_arg_ty); + return DepNode::construct(_tcx, DepKind::$variant, &arg) + })* + + return DepNode::construct(_tcx, DepKind::$variant, &()) + } + )* + } + + pub type DepNode = rustc_query_system::dep_graph::DepNode<DepKind>; + + pub trait DepNodeExt: Sized { + /// Construct a DepNode from the given DepKind and DefPathHash. This + /// method will assert that the given DepKind actually requires a + /// single DefId/DefPathHash parameter. + fn from_def_path_hash(def_path_hash: DefPathHash, kind: DepKind) -> Self; + + /// Extracts the DefId corresponding to this DepNode. This will work + /// if two conditions are met: + /// + /// 1. The Fingerprint of the DepNode actually is a DefPathHash, and + /// 2. the item that the DefPath refers to exists in the current tcx. + /// + /// Condition (1) is determined by the DepKind variant of the + /// DepNode. Condition (2) might not be fulfilled if a DepNode + /// refers to something from the previous compilation session that + /// has been removed. + fn extract_def_id(&self, tcx: TyCtxt<'_>) -> Option<DefId>; + + /// Used in testing + fn from_label_string(label: &str, def_path_hash: DefPathHash) + -> Result<Self, ()>; + + /// Used in testing + fn has_label_string(label: &str) -> bool; + } + + impl DepNodeExt for DepNode { + /// Construct a DepNode from the given DepKind and DefPathHash. This + /// method will assert that the given DepKind actually requires a + /// single DefId/DefPathHash parameter. + fn from_def_path_hash(def_path_hash: DefPathHash, kind: DepKind) -> DepNode { + debug_assert!(kind.can_reconstruct_query_key() && kind.has_params()); + DepNode { + kind, + hash: def_path_hash.0, + } + } + + /// Extracts the DefId corresponding to this DepNode. This will work + /// if two conditions are met: + /// + /// 1. The Fingerprint of the DepNode actually is a DefPathHash, and + /// 2. the item that the DefPath refers to exists in the current tcx. + /// + /// Condition (1) is determined by the DepKind variant of the + /// DepNode. Condition (2) might not be fulfilled if a DepNode + /// refers to something from the previous compilation session that + /// has been removed. + fn extract_def_id(&self, tcx: TyCtxt<'tcx>) -> Option<DefId> { + if self.kind.can_reconstruct_query_key() { + let def_path_hash = DefPathHash(self.hash); + tcx.def_path_hash_to_def_id.as_ref()?.get(&def_path_hash).cloned() + } else { + None + } + } + + /// Used in testing + fn from_label_string(label: &str, def_path_hash: DefPathHash) -> Result<DepNode, ()> { + let kind = match label { + $( + stringify!($variant) => DepKind::$variant, + )* + _ => return Err(()), + }; + + if !kind.can_reconstruct_query_key() { + return Err(()); + } + + if kind.has_params() { + Ok(DepNode::from_def_path_hash(def_path_hash, kind)) + } else { + Ok(DepNode::new_no_params(kind)) + } + } + + /// Used in testing + fn has_label_string(label: &str) -> bool { + match label { + $( + stringify!($variant) => true, + )* + _ => false, + } + } + } + + /// Contains variant => str representations for constructing + /// DepNode groups for tests. + #[allow(dead_code, non_upper_case_globals)] + pub mod label_strs { + $( + pub const $variant: &str = stringify!($variant); + )* + } + ); +} + +rustc_dep_node_append!([define_dep_nodes!][ <'tcx> + // We use this for most things when incr. comp. is turned off. + [] Null, + + // Represents metadata from an extern crate. + [eval_always] CrateMetadata(CrateNum), + + [anon] TraitSelect, + + [] CompileCodegenUnit(Symbol), +]); + +impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for DefId { + #[inline] + fn can_reconstruct_query_key() -> bool { + true + } + + fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint { + tcx.def_path_hash(*self).0 + } + + fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String { + tcx.def_path_str(*self) + } + + fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> { + dep_node.extract_def_id(tcx) + } +} + +impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for LocalDefId { + #[inline] + fn can_reconstruct_query_key() -> bool { + true + } + + fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint { + self.to_def_id().to_fingerprint(tcx) + } + + fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String { + self.to_def_id().to_debug_str(tcx) + } + + fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> { + dep_node.extract_def_id(tcx).map(|id| id.expect_local()) + } +} + +impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for CrateNum { + #[inline] + fn can_reconstruct_query_key() -> bool { + true + } + + fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint { + let def_id = DefId { krate: *self, index: CRATE_DEF_INDEX }; + tcx.def_path_hash(def_id).0 + } + + fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String { + tcx.crate_name(*self).to_string() + } + + fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> { + dep_node.extract_def_id(tcx).map(|id| id.krate) + } +} + +impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for (DefId, DefId) { + #[inline] + fn can_reconstruct_query_key() -> bool { + false + } + + // We actually would not need to specialize the implementation of this + // method but it's faster to combine the hashes than to instantiate a full + // hashing context and stable-hashing state. + fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint { + let (def_id_0, def_id_1) = *self; + + let def_path_hash_0 = tcx.def_path_hash(def_id_0); + let def_path_hash_1 = tcx.def_path_hash(def_id_1); + + def_path_hash_0.0.combine(def_path_hash_1.0) + } + + fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String { + let (def_id_0, def_id_1) = *self; + + format!("({}, {})", tcx.def_path_debug_str(def_id_0), tcx.def_path_debug_str(def_id_1)) + } +} + +impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for HirId { + #[inline] + fn can_reconstruct_query_key() -> bool { + false + } + + // We actually would not need to specialize the implementation of this + // method but it's faster to combine the hashes than to instantiate a full + // hashing context and stable-hashing state. + fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint { + let HirId { owner, local_id } = *self; + + let def_path_hash = tcx.def_path_hash(owner.to_def_id()); + let local_id = Fingerprint::from_smaller_hash(local_id.as_u32().into()); + + def_path_hash.0.combine(local_id) + } +} diff --git a/compiler/rustc_middle/src/dep_graph/mod.rs b/compiler/rustc_middle/src/dep_graph/mod.rs new file mode 100644 index 00000000000..66975242798 --- /dev/null +++ b/compiler/rustc_middle/src/dep_graph/mod.rs @@ -0,0 +1,190 @@ +use crate::ich::StableHashingContext; +use crate::ty::query::try_load_from_on_disk_cache; +use crate::ty::{self, TyCtxt}; +use rustc_data_structures::profiling::SelfProfilerRef; +use rustc_data_structures::sync::Lock; +use rustc_data_structures::thin_vec::ThinVec; +use rustc_errors::Diagnostic; +use rustc_hir::def_id::LocalDefId; + +mod dep_node; + +pub(crate) use rustc_query_system::dep_graph::DepNodeParams; +pub use rustc_query_system::dep_graph::{ + debug, hash_result, DepContext, DepNodeColor, DepNodeIndex, SerializedDepNodeIndex, + WorkProduct, WorkProductId, +}; + +pub use dep_node::{label_strs, DepConstructor, DepKind, DepNode, DepNodeExt}; + +pub type DepGraph = rustc_query_system::dep_graph::DepGraph<DepKind>; +pub type TaskDeps = rustc_query_system::dep_graph::TaskDeps<DepKind>; +pub type DepGraphQuery = rustc_query_system::dep_graph::DepGraphQuery<DepKind>; +pub type PreviousDepGraph = rustc_query_system::dep_graph::PreviousDepGraph<DepKind>; +pub type SerializedDepGraph = rustc_query_system::dep_graph::SerializedDepGraph<DepKind>; + +impl rustc_query_system::dep_graph::DepKind for DepKind { + const NULL: Self = DepKind::Null; + + fn is_eval_always(&self) -> bool { + DepKind::is_eval_always(self) + } + + fn has_params(&self) -> bool { + DepKind::has_params(self) + } + + fn debug_node(node: &DepNode, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + write!(f, "{:?}", node.kind)?; + + if !node.kind.has_params() && !node.kind.is_anon() { + return Ok(()); + } + + write!(f, "(")?; + + ty::tls::with_opt(|opt_tcx| { + if let Some(tcx) = opt_tcx { + if let Some(def_id) = node.extract_def_id(tcx) { + write!(f, "{}", tcx.def_path_debug_str(def_id))?; + } else if let Some(ref s) = tcx.dep_graph.dep_node_debug_str(*node) { + write!(f, "{}", s)?; + } else { + write!(f, "{}", node.hash)?; + } + } else { + write!(f, "{}", node.hash)?; + } + Ok(()) + })?; + + write!(f, ")") + } + + fn with_deps<OP, R>(task_deps: Option<&Lock<TaskDeps>>, op: OP) -> R + where + OP: FnOnce() -> R, + { + ty::tls::with_context(|icx| { + let icx = ty::tls::ImplicitCtxt { task_deps, ..icx.clone() }; + + ty::tls::enter_context(&icx, |_| op()) + }) + } + + fn read_deps<OP>(op: OP) + where + OP: for<'a> FnOnce(Option<&'a Lock<TaskDeps>>), + { + ty::tls::with_context_opt(|icx| { + let icx = if let Some(icx) = icx { icx } else { return }; + op(icx.task_deps) + }) + } + + fn can_reconstruct_query_key(&self) -> bool { + DepKind::can_reconstruct_query_key(self) + } +} + +impl<'tcx> DepContext for TyCtxt<'tcx> { + type DepKind = DepKind; + type StableHashingContext = StableHashingContext<'tcx>; + + fn create_stable_hashing_context(&self) -> Self::StableHashingContext { + TyCtxt::create_stable_hashing_context(*self) + } + + fn debug_dep_tasks(&self) -> bool { + self.sess.opts.debugging_opts.dep_tasks + } + fn debug_dep_node(&self) -> bool { + self.sess.opts.debugging_opts.incremental_info + || self.sess.opts.debugging_opts.query_dep_graph + } + + fn try_force_from_dep_node(&self, dep_node: &DepNode) -> bool { + // FIXME: This match is just a workaround for incremental bugs and should + // be removed. https://github.com/rust-lang/rust/issues/62649 is one such + // bug that must be fixed before removing this. + match dep_node.kind { + DepKind::hir_owner | DepKind::hir_owner_nodes | DepKind::CrateMetadata => { + if let Some(def_id) = dep_node.extract_def_id(*self) { + if def_id_corresponds_to_hir_dep_node(*self, def_id.expect_local()) { + if dep_node.kind == DepKind::CrateMetadata { + // The `DefPath` has corresponding node, + // and that node should have been marked + // either red or green in `data.colors`. + bug!( + "DepNode {:?} should have been \ + pre-marked as red or green but wasn't.", + dep_node + ); + } + } else { + // This `DefPath` does not have a + // corresponding `DepNode` (e.g. a + // struct field), and the ` DefPath` + // collided with the `DefPath` of a + // proper item that existed in the + // previous compilation session. + // + // Since the given `DefPath` does not + // denote the item that previously + // existed, we just fail to mark green. + return false; + } + } else { + // If the node does not exist anymore, we + // just fail to mark green. + return false; + } + } + _ => { + // For other kinds of nodes it's OK to be + // forced. + } + } + + debug!("try_force_from_dep_node({:?}) --- trying to force", dep_node); + ty::query::force_from_dep_node(*self, dep_node) + } + + fn has_errors_or_delayed_span_bugs(&self) -> bool { + self.sess.has_errors_or_delayed_span_bugs() + } + + fn diagnostic(&self) -> &rustc_errors::Handler { + self.sess.diagnostic() + } + + // Interactions with on_disk_cache + fn try_load_from_on_disk_cache(&self, dep_node: &DepNode) { + try_load_from_on_disk_cache(*self, dep_node) + } + + fn load_diagnostics(&self, prev_dep_node_index: SerializedDepNodeIndex) -> Vec<Diagnostic> { + self.queries.on_disk_cache.load_diagnostics(*self, prev_dep_node_index) + } + + fn store_diagnostics(&self, dep_node_index: DepNodeIndex, diagnostics: ThinVec<Diagnostic>) { + self.queries.on_disk_cache.store_diagnostics(dep_node_index, diagnostics) + } + + fn store_diagnostics_for_anon_node( + &self, + dep_node_index: DepNodeIndex, + diagnostics: ThinVec<Diagnostic>, + ) { + self.queries.on_disk_cache.store_diagnostics_for_anon_node(dep_node_index, diagnostics) + } + + fn profiler(&self) -> &SelfProfilerRef { + &self.prof + } +} + +fn def_id_corresponds_to_hir_dep_node(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool { + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); + def_id == hir_id.owner +} diff --git a/compiler/rustc_middle/src/hir/exports.rs b/compiler/rustc_middle/src/hir/exports.rs new file mode 100644 index 00000000000..be9e38aca65 --- /dev/null +++ b/compiler/rustc_middle/src/hir/exports.rs @@ -0,0 +1,33 @@ +use crate::ty; + +use rustc_data_structures::fx::FxHashMap; +use rustc_hir::def::Res; +use rustc_hir::def_id::LocalDefId; +use rustc_macros::HashStable; +use rustc_span::symbol::Ident; +use rustc_span::Span; + +use std::fmt::Debug; + +/// This is the replacement export map. It maps a module to all of the exports +/// within. +pub type ExportMap<Id> = FxHashMap<LocalDefId, Vec<Export<Id>>>; + +#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct Export<Id> { + /// The name of the target. + pub ident: Ident, + /// The resolution of the target. + pub res: Res<Id>, + /// The span of the target. + pub span: Span, + /// The visibility of the export. + /// We include non-`pub` exports for hygienic macros that get used from extern crates. + pub vis: ty::Visibility, +} + +impl<Id> Export<Id> { + pub fn map_id<R>(self, map: impl FnMut(Id) -> R) -> Export<R> { + Export { ident: self.ident, res: self.res.map_id(map), span: self.span, vis: self.vis } + } +} diff --git a/compiler/rustc_middle/src/hir/map/blocks.rs b/compiler/rustc_middle/src/hir/map/blocks.rs new file mode 100644 index 00000000000..6f572a4875f --- /dev/null +++ b/compiler/rustc_middle/src/hir/map/blocks.rs @@ -0,0 +1,263 @@ +//! This module provides a simplified abstraction for working with +//! code blocks identified by their integer `NodeId`. In particular, +//! it captures a common set of attributes that all "function-like +//! things" (represented by `FnLike` instances) share. For example, +//! all `FnLike` instances have a type signature (be it explicit or +//! inferred). And all `FnLike` instances have a body, i.e., the code +//! that is run when the function-like thing it represents is invoked. +//! +//! With the above abstraction in place, one can treat the program +//! text as a collection of blocks of code (and most such blocks are +//! nested within a uniquely determined `FnLike`), and users can ask +//! for the `Code` associated with a particular NodeId. + +use crate::hir::map::Map; +use rustc_ast::Attribute; +use rustc_hir as hir; +use rustc_hir::intravisit::FnKind; +use rustc_hir::{Expr, FnDecl, Node}; +use rustc_span::symbol::Ident; +use rustc_span::Span; + +/// An FnLikeNode is a Node that is like a fn, in that it has a decl +/// and a body (as well as a NodeId, a span, etc). +/// +/// More specifically, it is one of either: +/// +/// - A function item, +/// - A closure expr (i.e., an ExprKind::Closure), or +/// - The default implementation for a trait method. +/// +/// To construct one, use the `Code::from_node` function. +#[derive(Copy, Clone, Debug)] +pub struct FnLikeNode<'a> { + node: Node<'a>, +} + +/// MaybeFnLike wraps a method that indicates if an object +/// corresponds to some FnLikeNode. +trait MaybeFnLike { + fn is_fn_like(&self) -> bool; +} + +impl MaybeFnLike for hir::Item<'_> { + fn is_fn_like(&self) -> bool { + match self.kind { + hir::ItemKind::Fn(..) => true, + _ => false, + } + } +} + +impl MaybeFnLike for hir::ImplItem<'_> { + fn is_fn_like(&self) -> bool { + match self.kind { + hir::ImplItemKind::Fn(..) => true, + _ => false, + } + } +} + +impl MaybeFnLike for hir::TraitItem<'_> { + fn is_fn_like(&self) -> bool { + match self.kind { + hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)) => true, + _ => false, + } + } +} + +impl MaybeFnLike for hir::Expr<'_> { + fn is_fn_like(&self) -> bool { + match self.kind { + hir::ExprKind::Closure(..) => true, + _ => false, + } + } +} + +/// Carries either an FnLikeNode or a Expr, as these are the two +/// constructs that correspond to "code" (as in, something from which +/// we can construct a control-flow graph). +#[derive(Copy, Clone)] +pub enum Code<'a> { + FnLike(FnLikeNode<'a>), + Expr(&'a Expr<'a>), +} + +impl<'a> Code<'a> { + pub fn id(&self) -> hir::HirId { + match *self { + Code::FnLike(node) => node.id(), + Code::Expr(block) => block.hir_id, + } + } + + /// Attempts to construct a Code from presumed FnLike or Expr node input. + pub fn from_node(map: &Map<'a>, id: hir::HirId) -> Option<Code<'a>> { + match map.get(id) { + Node::Block(_) => { + // Use the parent, hopefully an expression node. + Code::from_node(map, map.get_parent_node(id)) + } + Node::Expr(expr) => Some(Code::Expr(expr)), + node => FnLikeNode::from_node(node).map(Code::FnLike), + } + } +} + +/// These are all the components one can extract from a fn item for +/// use when implementing FnLikeNode operations. +struct ItemFnParts<'a> { + ident: Ident, + decl: &'a hir::FnDecl<'a>, + header: hir::FnHeader, + vis: &'a hir::Visibility<'a>, + generics: &'a hir::Generics<'a>, + body: hir::BodyId, + id: hir::HirId, + span: Span, + attrs: &'a [Attribute], +} + +/// These are all the components one can extract from a closure expr +/// for use when implementing FnLikeNode operations. +struct ClosureParts<'a> { + decl: &'a FnDecl<'a>, + body: hir::BodyId, + id: hir::HirId, + span: Span, + attrs: &'a [Attribute], +} + +impl<'a> ClosureParts<'a> { + fn new( + d: &'a FnDecl<'a>, + b: hir::BodyId, + id: hir::HirId, + s: Span, + attrs: &'a [Attribute], + ) -> Self { + ClosureParts { decl: d, body: b, id, span: s, attrs } + } +} + +impl<'a> FnLikeNode<'a> { + /// Attempts to construct a FnLikeNode from presumed FnLike node input. + pub fn from_node(node: Node<'_>) -> Option<FnLikeNode<'_>> { + let fn_like = match node { + Node::Item(item) => item.is_fn_like(), + Node::TraitItem(tm) => tm.is_fn_like(), + Node::ImplItem(it) => it.is_fn_like(), + Node::Expr(e) => e.is_fn_like(), + _ => false, + }; + fn_like.then_some(FnLikeNode { node }) + } + + pub fn body(self) -> hir::BodyId { + self.handle( + |i: ItemFnParts<'a>| i.body, + |_, _, _: &'a hir::FnSig<'a>, _, body: hir::BodyId, _, _| body, + |c: ClosureParts<'a>| c.body, + ) + } + + pub fn decl(self) -> &'a FnDecl<'a> { + self.handle( + |i: ItemFnParts<'a>| &*i.decl, + |_, _, sig: &'a hir::FnSig<'a>, _, _, _, _| &sig.decl, + |c: ClosureParts<'a>| c.decl, + ) + } + + pub fn span(self) -> Span { + self.handle( + |i: ItemFnParts<'_>| i.span, + |_, _, _: &'a hir::FnSig<'a>, _, _, span, _| span, + |c: ClosureParts<'_>| c.span, + ) + } + + pub fn id(self) -> hir::HirId { + self.handle( + |i: ItemFnParts<'_>| i.id, + |id, _, _: &'a hir::FnSig<'a>, _, _, _, _| id, + |c: ClosureParts<'_>| c.id, + ) + } + + pub fn constness(self) -> hir::Constness { + self.kind().header().map_or(hir::Constness::NotConst, |header| header.constness) + } + + pub fn asyncness(self) -> hir::IsAsync { + self.kind().header().map_or(hir::IsAsync::NotAsync, |header| header.asyncness) + } + + pub fn unsafety(self) -> hir::Unsafety { + self.kind().header().map_or(hir::Unsafety::Normal, |header| header.unsafety) + } + + pub fn kind(self) -> FnKind<'a> { + let item = |p: ItemFnParts<'a>| -> FnKind<'a> { + FnKind::ItemFn(p.ident, p.generics, p.header, p.vis, p.attrs) + }; + let closure = |c: ClosureParts<'a>| FnKind::Closure(c.attrs); + let method = |_, ident: Ident, sig: &'a hir::FnSig<'a>, vis, _, _, attrs| { + FnKind::Method(ident, sig, vis, attrs) + }; + self.handle(item, method, closure) + } + + fn handle<A, I, M, C>(self, item_fn: I, method: M, closure: C) -> A + where + I: FnOnce(ItemFnParts<'a>) -> A, + M: FnOnce( + hir::HirId, + Ident, + &'a hir::FnSig<'a>, + Option<&'a hir::Visibility<'a>>, + hir::BodyId, + Span, + &'a [Attribute], + ) -> A, + C: FnOnce(ClosureParts<'a>) -> A, + { + match self.node { + Node::Item(i) => match i.kind { + hir::ItemKind::Fn(ref sig, ref generics, block) => item_fn(ItemFnParts { + id: i.hir_id, + ident: i.ident, + decl: &sig.decl, + body: block, + vis: &i.vis, + span: i.span, + attrs: &i.attrs, + header: sig.header, + generics, + }), + _ => bug!("item FnLikeNode that is not fn-like"), + }, + Node::TraitItem(ti) => match ti.kind { + hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => { + method(ti.hir_id, ti.ident, sig, None, body, ti.span, &ti.attrs) + } + _ => bug!("trait method FnLikeNode that is not fn-like"), + }, + Node::ImplItem(ii) => match ii.kind { + hir::ImplItemKind::Fn(ref sig, body) => { + method(ii.hir_id, ii.ident, sig, Some(&ii.vis), body, ii.span, &ii.attrs) + } + _ => bug!("impl method FnLikeNode that is not fn-like"), + }, + Node::Expr(e) => match e.kind { + hir::ExprKind::Closure(_, ref decl, block, _fn_decl_span, _gen) => { + closure(ClosureParts::new(&decl, block, e.hir_id, e.span, &e.attrs)) + } + _ => bug!("expr FnLikeNode that is not fn-like"), + }, + _ => bug!("other FnLikeNode that is not fn-like"), + } + } +} diff --git a/compiler/rustc_middle/src/hir/map/collector.rs b/compiler/rustc_middle/src/hir/map/collector.rs new file mode 100644 index 00000000000..dce06a5f7ee --- /dev/null +++ b/compiler/rustc_middle/src/hir/map/collector.rs @@ -0,0 +1,559 @@ +use crate::arena::Arena; +use crate::hir::map::{Entry, HirOwnerData, Map}; +use crate::hir::{Owner, OwnerNodes, ParentedNode}; +use crate::ich::StableHashingContext; +use crate::middle::cstore::CrateStore; +use rustc_data_structures::fingerprint::Fingerprint; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_data_structures::svh::Svh; +use rustc_hir as hir; +use rustc_hir::def_id::CRATE_DEF_INDEX; +use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE}; +use rustc_hir::definitions::{self, DefPathHash}; +use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor}; +use rustc_hir::*; +use rustc_index::vec::{Idx, IndexVec}; +use rustc_session::{CrateDisambiguator, Session}; +use rustc_span::source_map::SourceMap; +use rustc_span::{Span, Symbol, DUMMY_SP}; + +use std::iter::repeat; + +/// A visitor that walks over the HIR and collects `Node`s into a HIR map. +pub(super) struct NodeCollector<'a, 'hir> { + arena: &'hir Arena<'hir>, + + /// The crate + krate: &'hir Crate<'hir>, + + /// Source map + source_map: &'a SourceMap, + + map: IndexVec<LocalDefId, HirOwnerData<'hir>>, + + /// The parent of this node + parent_node: hir::HirId, + + current_dep_node_owner: LocalDefId, + + definitions: &'a definitions::Definitions, + + hcx: StableHashingContext<'a>, + + // We are collecting HIR hashes here so we can compute the + // crate hash from them later on. + hir_body_nodes: Vec<(DefPathHash, Fingerprint)>, +} + +fn insert_vec_map<K: Idx, V: Clone>(map: &mut IndexVec<K, Option<V>>, k: K, v: V) { + let i = k.index(); + let len = map.len(); + if i >= len { + map.extend(repeat(None).take(i - len + 1)); + } + map[k] = Some(v); +} + +fn hash( + hcx: &mut StableHashingContext<'_>, + input: impl for<'a> HashStable<StableHashingContext<'a>>, +) -> Fingerprint { + let mut stable_hasher = StableHasher::new(); + input.hash_stable(hcx, &mut stable_hasher); + stable_hasher.finish() +} + +fn hash_body( + hcx: &mut StableHashingContext<'_>, + def_path_hash: DefPathHash, + item_like: impl for<'a> HashStable<StableHashingContext<'a>>, + hir_body_nodes: &mut Vec<(DefPathHash, Fingerprint)>, +) -> Fingerprint { + let hash = hash(hcx, HirItemLike { item_like: &item_like }); + hir_body_nodes.push((def_path_hash, hash)); + hash +} + +fn upstream_crates(cstore: &dyn CrateStore) -> Vec<(Symbol, Fingerprint, Svh)> { + let mut upstream_crates: Vec<_> = cstore + .crates_untracked() + .iter() + .map(|&cnum| { + let name = cstore.crate_name_untracked(cnum); + let disambiguator = cstore.crate_disambiguator_untracked(cnum).to_fingerprint(); + let hash = cstore.crate_hash_untracked(cnum); + (name, disambiguator, hash) + }) + .collect(); + upstream_crates.sort_unstable_by_key(|&(name, dis, _)| (name.as_str(), dis)); + upstream_crates +} + +impl<'a, 'hir> NodeCollector<'a, 'hir> { + pub(super) fn root( + sess: &'a Session, + arena: &'hir Arena<'hir>, + krate: &'hir Crate<'hir>, + definitions: &'a definitions::Definitions, + mut hcx: StableHashingContext<'a>, + ) -> NodeCollector<'a, 'hir> { + let root_mod_def_path_hash = + definitions.def_path_hash(LocalDefId { local_def_index: CRATE_DEF_INDEX }); + + let mut hir_body_nodes = Vec::new(); + + let hash = { + let Crate { + ref item, + // These fields are handled separately: + exported_macros: _, + non_exported_macro_attrs: _, + items: _, + trait_items: _, + impl_items: _, + bodies: _, + trait_impls: _, + body_ids: _, + modules: _, + proc_macros: _, + trait_map: _, + } = *krate; + + hash_body(&mut hcx, root_mod_def_path_hash, item, &mut hir_body_nodes) + }; + + let mut collector = NodeCollector { + arena, + krate, + source_map: sess.source_map(), + parent_node: hir::CRATE_HIR_ID, + current_dep_node_owner: LocalDefId { local_def_index: CRATE_DEF_INDEX }, + definitions, + hcx, + hir_body_nodes, + map: (0..definitions.def_index_count()) + .map(|_| HirOwnerData { signature: None, with_bodies: None }) + .collect(), + }; + collector.insert_entry( + hir::CRATE_HIR_ID, + Entry { parent: hir::CRATE_HIR_ID, node: Node::Crate(&krate.item) }, + hash, + ); + + collector + } + + pub(super) fn finalize_and_compute_crate_hash( + mut self, + crate_disambiguator: CrateDisambiguator, + cstore: &dyn CrateStore, + commandline_args_hash: u64, + ) -> (IndexVec<LocalDefId, HirOwnerData<'hir>>, Svh) { + // Insert bodies into the map + for (id, body) in self.krate.bodies.iter() { + let bodies = &mut self.map[id.hir_id.owner].with_bodies.as_mut().unwrap().bodies; + assert!(bodies.insert(id.hir_id.local_id, body).is_none()); + } + + self.hir_body_nodes.sort_unstable_by_key(|bn| bn.0); + + let node_hashes = self.hir_body_nodes.iter().fold( + Fingerprint::ZERO, + |combined_fingerprint, &(def_path_hash, fingerprint)| { + combined_fingerprint.combine(def_path_hash.0.combine(fingerprint)) + }, + ); + + let upstream_crates = upstream_crates(cstore); + + // We hash the final, remapped names of all local source files so we + // don't have to include the path prefix remapping commandline args. + // If we included the full mapping in the SVH, we could only have + // reproducible builds by compiling from the same directory. So we just + // hash the result of the mapping instead of the mapping itself. + let mut source_file_names: Vec<_> = self + .source_map + .files() + .iter() + .filter(|source_file| source_file.cnum == LOCAL_CRATE) + .map(|source_file| source_file.name_hash) + .collect(); + + source_file_names.sort_unstable(); + + let crate_hash_input = ( + ((node_hashes, upstream_crates), source_file_names), + (commandline_args_hash, crate_disambiguator.to_fingerprint()), + ); + + let mut stable_hasher = StableHasher::new(); + crate_hash_input.hash_stable(&mut self.hcx, &mut stable_hasher); + let crate_hash: Fingerprint = stable_hasher.finish(); + + let svh = Svh::new(crate_hash.to_smaller_hash()); + (self.map, svh) + } + + fn insert_entry(&mut self, id: HirId, entry: Entry<'hir>, hash: Fingerprint) { + let i = id.local_id.as_u32() as usize; + + let arena = self.arena; + + let data = &mut self.map[id.owner]; + + if data.with_bodies.is_none() { + data.with_bodies = Some(arena.alloc(OwnerNodes { + hash, + nodes: IndexVec::new(), + bodies: FxHashMap::default(), + })); + } + + let nodes = data.with_bodies.as_mut().unwrap(); + + if i == 0 { + // Overwrite the dummy hash with the real HIR owner hash. + nodes.hash = hash; + + // FIXME: feature(impl_trait_in_bindings) broken and trigger this assert + //assert!(data.signature.is_none()); + + data.signature = + Some(self.arena.alloc(Owner { parent: entry.parent, node: entry.node })); + } else { + assert_eq!(entry.parent.owner, id.owner); + insert_vec_map( + &mut nodes.nodes, + id.local_id, + ParentedNode { parent: entry.parent.local_id, node: entry.node }, + ); + } + } + + fn insert(&mut self, span: Span, hir_id: HirId, node: Node<'hir>) { + self.insert_with_hash(span, hir_id, node, Fingerprint::ZERO) + } + + fn insert_with_hash(&mut self, span: Span, hir_id: HirId, node: Node<'hir>, hash: Fingerprint) { + let entry = Entry { parent: self.parent_node, node }; + + // Make sure that the DepNode of some node coincides with the HirId + // owner of that node. + if cfg!(debug_assertions) { + if hir_id.owner != self.current_dep_node_owner { + let node_str = match self.definitions.opt_hir_id_to_local_def_id(hir_id) { + Some(def_id) => self.definitions.def_path(def_id).to_string_no_crate(), + None => format!("{:?}", node), + }; + + span_bug!( + span, + "inconsistent DepNode at `{:?}` for `{}`: \ + current_dep_node_owner={} ({:?}), hir_id.owner={} ({:?})", + self.source_map.span_to_string(span), + node_str, + self.definitions.def_path(self.current_dep_node_owner).to_string_no_crate(), + self.current_dep_node_owner, + self.definitions.def_path(hir_id.owner).to_string_no_crate(), + hir_id.owner, + ) + } + } + + self.insert_entry(hir_id, entry, hash); + } + + fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_node_id: HirId, f: F) { + let parent_node = self.parent_node; + self.parent_node = parent_node_id; + f(self); + self.parent_node = parent_node; + } + + fn with_dep_node_owner< + T: for<'b> HashStable<StableHashingContext<'b>>, + F: FnOnce(&mut Self, Fingerprint), + >( + &mut self, + dep_node_owner: LocalDefId, + item_like: &T, + f: F, + ) { + let prev_owner = self.current_dep_node_owner; + + let def_path_hash = self.definitions.def_path_hash(dep_node_owner); + + let hash = hash_body(&mut self.hcx, def_path_hash, item_like, &mut self.hir_body_nodes); + + self.current_dep_node_owner = dep_node_owner; + f(self, hash); + self.current_dep_node_owner = prev_owner; + } +} + +impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> { + type Map = Map<'hir>; + + /// Because we want to track parent items and so forth, enable + /// deep walking so that we walk nested items in the context of + /// their outer items. + + fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { + panic!("`visit_nested_xxx` must be manually implemented in this visitor"); + } + + fn visit_nested_item(&mut self, item: ItemId) { + debug!("visit_nested_item: {:?}", item); + self.visit_item(self.krate.item(item.id)); + } + + fn visit_nested_trait_item(&mut self, item_id: TraitItemId) { + self.visit_trait_item(self.krate.trait_item(item_id)); + } + + fn visit_nested_impl_item(&mut self, item_id: ImplItemId) { + self.visit_impl_item(self.krate.impl_item(item_id)); + } + + fn visit_nested_body(&mut self, id: BodyId) { + self.visit_body(self.krate.body(id)); + } + + fn visit_param(&mut self, param: &'hir Param<'hir>) { + let node = Node::Param(param); + self.insert(param.pat.span, param.hir_id, node); + self.with_parent(param.hir_id, |this| { + intravisit::walk_param(this, param); + }); + } + + fn visit_item(&mut self, i: &'hir Item<'hir>) { + debug!("visit_item: {:?}", i); + debug_assert_eq!( + i.hir_id.owner, + self.definitions.opt_hir_id_to_local_def_id(i.hir_id).unwrap() + ); + self.with_dep_node_owner(i.hir_id.owner, i, |this, hash| { + this.insert_with_hash(i.span, i.hir_id, Node::Item(i), hash); + this.with_parent(i.hir_id, |this| { + if let ItemKind::Struct(ref struct_def, _) = i.kind { + // If this is a tuple or unit-like struct, register the constructor. + if let Some(ctor_hir_id) = struct_def.ctor_hir_id() { + this.insert(i.span, ctor_hir_id, Node::Ctor(struct_def)); + } + } + intravisit::walk_item(this, i); + }); + }); + } + + fn visit_foreign_item(&mut self, foreign_item: &'hir ForeignItem<'hir>) { + self.insert(foreign_item.span, foreign_item.hir_id, Node::ForeignItem(foreign_item)); + + self.with_parent(foreign_item.hir_id, |this| { + intravisit::walk_foreign_item(this, foreign_item); + }); + } + + fn visit_generic_param(&mut self, param: &'hir GenericParam<'hir>) { + self.insert(param.span, param.hir_id, Node::GenericParam(param)); + intravisit::walk_generic_param(self, param); + } + + fn visit_trait_item(&mut self, ti: &'hir TraitItem<'hir>) { + debug_assert_eq!( + ti.hir_id.owner, + self.definitions.opt_hir_id_to_local_def_id(ti.hir_id).unwrap() + ); + self.with_dep_node_owner(ti.hir_id.owner, ti, |this, hash| { + this.insert_with_hash(ti.span, ti.hir_id, Node::TraitItem(ti), hash); + + this.with_parent(ti.hir_id, |this| { + intravisit::walk_trait_item(this, ti); + }); + }); + } + + fn visit_impl_item(&mut self, ii: &'hir ImplItem<'hir>) { + debug_assert_eq!( + ii.hir_id.owner, + self.definitions.opt_hir_id_to_local_def_id(ii.hir_id).unwrap() + ); + self.with_dep_node_owner(ii.hir_id.owner, ii, |this, hash| { + this.insert_with_hash(ii.span, ii.hir_id, Node::ImplItem(ii), hash); + + this.with_parent(ii.hir_id, |this| { + intravisit::walk_impl_item(this, ii); + }); + }); + } + + fn visit_pat(&mut self, pat: &'hir Pat<'hir>) { + let node = + if let PatKind::Binding(..) = pat.kind { Node::Binding(pat) } else { Node::Pat(pat) }; + self.insert(pat.span, pat.hir_id, node); + + self.with_parent(pat.hir_id, |this| { + intravisit::walk_pat(this, pat); + }); + } + + fn visit_arm(&mut self, arm: &'hir Arm<'hir>) { + let node = Node::Arm(arm); + + self.insert(arm.span, arm.hir_id, node); + + self.with_parent(arm.hir_id, |this| { + intravisit::walk_arm(this, arm); + }); + } + + fn visit_anon_const(&mut self, constant: &'hir AnonConst) { + self.insert(DUMMY_SP, constant.hir_id, Node::AnonConst(constant)); + + self.with_parent(constant.hir_id, |this| { + intravisit::walk_anon_const(this, constant); + }); + } + + fn visit_expr(&mut self, expr: &'hir Expr<'hir>) { + self.insert(expr.span, expr.hir_id, Node::Expr(expr)); + + self.with_parent(expr.hir_id, |this| { + intravisit::walk_expr(this, expr); + }); + } + + fn visit_stmt(&mut self, stmt: &'hir Stmt<'hir>) { + self.insert(stmt.span, stmt.hir_id, Node::Stmt(stmt)); + + self.with_parent(stmt.hir_id, |this| { + intravisit::walk_stmt(this, stmt); + }); + } + + fn visit_path_segment(&mut self, path_span: Span, path_segment: &'hir PathSegment<'hir>) { + if let Some(hir_id) = path_segment.hir_id { + self.insert(path_span, hir_id, Node::PathSegment(path_segment)); + } + intravisit::walk_path_segment(self, path_span, path_segment); + } + + fn visit_ty(&mut self, ty: &'hir Ty<'hir>) { + self.insert(ty.span, ty.hir_id, Node::Ty(ty)); + + self.with_parent(ty.hir_id, |this| { + intravisit::walk_ty(this, ty); + }); + } + + fn visit_trait_ref(&mut self, tr: &'hir TraitRef<'hir>) { + self.insert(tr.path.span, tr.hir_ref_id, Node::TraitRef(tr)); + + self.with_parent(tr.hir_ref_id, |this| { + intravisit::walk_trait_ref(this, tr); + }); + } + + fn visit_fn( + &mut self, + fk: intravisit::FnKind<'hir>, + fd: &'hir FnDecl<'hir>, + b: BodyId, + s: Span, + id: HirId, + ) { + assert_eq!(self.parent_node, id); + intravisit::walk_fn(self, fk, fd, b, s, id); + } + + fn visit_block(&mut self, block: &'hir Block<'hir>) { + self.insert(block.span, block.hir_id, Node::Block(block)); + self.with_parent(block.hir_id, |this| { + intravisit::walk_block(this, block); + }); + } + + fn visit_local(&mut self, l: &'hir Local<'hir>) { + self.insert(l.span, l.hir_id, Node::Local(l)); + self.with_parent(l.hir_id, |this| intravisit::walk_local(this, l)) + } + + fn visit_lifetime(&mut self, lifetime: &'hir Lifetime) { + self.insert(lifetime.span, lifetime.hir_id, Node::Lifetime(lifetime)); + } + + fn visit_vis(&mut self, visibility: &'hir Visibility<'hir>) { + match visibility.node { + VisibilityKind::Public | VisibilityKind::Crate(_) | VisibilityKind::Inherited => {} + VisibilityKind::Restricted { hir_id, .. } => { + self.insert(visibility.span, hir_id, Node::Visibility(visibility)); + self.with_parent(hir_id, |this| { + intravisit::walk_vis(this, visibility); + }); + } + } + } + + fn visit_macro_def(&mut self, macro_def: &'hir MacroDef<'hir>) { + self.with_dep_node_owner(macro_def.hir_id.owner, macro_def, |this, hash| { + this.insert_with_hash( + macro_def.span, + macro_def.hir_id, + Node::MacroDef(macro_def), + hash, + ); + }); + } + + fn visit_variant(&mut self, v: &'hir Variant<'hir>, g: &'hir Generics<'hir>, item_id: HirId) { + self.insert(v.span, v.id, Node::Variant(v)); + self.with_parent(v.id, |this| { + // Register the constructor of this variant. + if let Some(ctor_hir_id) = v.data.ctor_hir_id() { + this.insert(v.span, ctor_hir_id, Node::Ctor(&v.data)); + } + intravisit::walk_variant(this, v, g, item_id); + }); + } + + fn visit_struct_field(&mut self, field: &'hir StructField<'hir>) { + self.insert(field.span, field.hir_id, Node::Field(field)); + self.with_parent(field.hir_id, |this| { + intravisit::walk_struct_field(this, field); + }); + } + + fn visit_trait_item_ref(&mut self, ii: &'hir TraitItemRef) { + // Do not visit the duplicate information in TraitItemRef. We want to + // map the actual nodes, not the duplicate ones in the *Ref. + let TraitItemRef { id, ident: _, kind: _, span: _, defaultness: _ } = *ii; + + self.visit_nested_trait_item(id); + } + + fn visit_impl_item_ref(&mut self, ii: &'hir ImplItemRef<'hir>) { + // Do not visit the duplicate information in ImplItemRef. We want to + // map the actual nodes, not the duplicate ones in the *Ref. + let ImplItemRef { id, ident: _, kind: _, span: _, vis: _, defaultness: _ } = *ii; + + self.visit_nested_impl_item(id); + } +} + +struct HirItemLike<T> { + item_like: T, +} + +impl<'hir, T> HashStable<StableHashingContext<'hir>> for HirItemLike<T> +where + T: HashStable<StableHashingContext<'hir>>, +{ + fn hash_stable(&self, hcx: &mut StableHashingContext<'hir>, hasher: &mut StableHasher) { + hcx.while_hashing_hir_bodies(true, |hcx| { + self.item_like.hash_stable(hcx, hasher); + }); + } +} diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs new file mode 100644 index 00000000000..1e57411f9c5 --- /dev/null +++ b/compiler/rustc_middle/src/hir/map/mod.rs @@ -0,0 +1,1090 @@ +use self::collector::NodeCollector; + +use crate::hir::{Owner, OwnerNodes}; +use crate::ty::query::Providers; +use crate::ty::TyCtxt; +use rustc_ast as ast; +use rustc_data_structures::svh::Svh; +use rustc_hir::def::{DefKind, Res}; +use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE}; +use rustc_hir::definitions::{DefKey, DefPath, Definitions}; +use rustc_hir::intravisit; +use rustc_hir::itemlikevisit::ItemLikeVisitor; +use rustc_hir::*; +use rustc_index::vec::IndexVec; +use rustc_span::hygiene::MacroKind; +use rustc_span::source_map::Spanned; +use rustc_span::symbol::{kw, Ident, Symbol}; +use rustc_span::Span; +use rustc_target::spec::abi::Abi; + +pub mod blocks; +mod collector; + +/// Represents an entry and its parent `HirId`. +#[derive(Copy, Clone, Debug)] +pub struct Entry<'hir> { + parent: HirId, + node: Node<'hir>, +} + +impl<'hir> Entry<'hir> { + fn parent_node(self) -> Option<HirId> { + match self.node { + Node::Crate(_) | Node::MacroDef(_) => None, + _ => Some(self.parent), + } + } +} + +fn fn_decl<'hir>(node: Node<'hir>) -> Option<&'hir FnDecl<'hir>> { + match node { + Node::Item(Item { kind: ItemKind::Fn(sig, _, _), .. }) + | Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(sig, _), .. }) + | Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(sig, _), .. }) => Some(&sig.decl), + Node::Expr(Expr { kind: ExprKind::Closure(_, fn_decl, ..), .. }) => Some(fn_decl), + _ => None, + } +} + +fn fn_sig<'hir>(node: Node<'hir>) -> Option<&'hir FnSig<'hir>> { + match &node { + Node::Item(Item { kind: ItemKind::Fn(sig, _, _), .. }) + | Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(sig, _), .. }) + | Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(sig, _), .. }) => Some(sig), + _ => None, + } +} + +pub fn associated_body<'hir>(node: Node<'hir>) -> Option<BodyId> { + match node { + Node::Item(Item { + kind: ItemKind::Const(_, body) | ItemKind::Static(.., body) | ItemKind::Fn(.., body), + .. + }) + | Node::TraitItem(TraitItem { + kind: + TraitItemKind::Const(_, Some(body)) | TraitItemKind::Fn(_, TraitFn::Provided(body)), + .. + }) + | Node::ImplItem(ImplItem { + kind: ImplItemKind::Const(_, body) | ImplItemKind::Fn(_, body), + .. + }) + | Node::Expr(Expr { kind: ExprKind::Closure(.., body, _, _), .. }) => Some(*body), + + Node::AnonConst(constant) => Some(constant.body), + + _ => None, + } +} + +fn is_body_owner<'hir>(node: Node<'hir>, hir_id: HirId) -> bool { + match associated_body(node) { + Some(b) => b.hir_id == hir_id, + None => false, + } +} + +pub(super) struct HirOwnerData<'hir> { + pub(super) signature: Option<&'hir Owner<'hir>>, + pub(super) with_bodies: Option<&'hir mut OwnerNodes<'hir>>, +} + +pub struct IndexedHir<'hir> { + /// The SVH of the local crate. + pub crate_hash: Svh, + + pub(super) map: IndexVec<LocalDefId, HirOwnerData<'hir>>, +} + +#[derive(Copy, Clone)] +pub struct Map<'hir> { + pub(super) tcx: TyCtxt<'hir>, +} + +/// An iterator that walks up the ancestor tree of a given `HirId`. +/// Constructed using `tcx.hir().parent_iter(hir_id)`. +pub struct ParentHirIterator<'map, 'hir> { + current_id: HirId, + map: &'map Map<'hir>, +} + +impl<'hir> Iterator for ParentHirIterator<'_, 'hir> { + type Item = (HirId, Node<'hir>); + + fn next(&mut self) -> Option<Self::Item> { + if self.current_id == CRATE_HIR_ID { + return None; + } + loop { + // There are nodes that do not have entries, so we need to skip them. + let parent_id = self.map.get_parent_node(self.current_id); + + if parent_id == self.current_id { + self.current_id = CRATE_HIR_ID; + return None; + } + + self.current_id = parent_id; + if let Some(entry) = self.map.find_entry(parent_id) { + return Some((parent_id, entry.node)); + } + // If this `HirId` doesn't have an `Entry`, skip it and look for its `parent_id`. + } + } +} + +impl<'hir> Map<'hir> { + pub fn krate(&self) -> &'hir Crate<'hir> { + self.tcx.hir_crate(LOCAL_CRATE) + } + + #[inline] + pub fn definitions(&self) -> &'hir Definitions { + &self.tcx.definitions + } + + pub fn def_key(&self, def_id: LocalDefId) -> DefKey { + self.tcx.definitions.def_key(def_id) + } + + pub fn def_path_from_hir_id(&self, id: HirId) -> Option<DefPath> { + self.opt_local_def_id(id).map(|def_id| self.def_path(def_id)) + } + + pub fn def_path(&self, def_id: LocalDefId) -> DefPath { + self.tcx.definitions.def_path(def_id) + } + + #[inline] + pub fn local_def_id(&self, hir_id: HirId) -> LocalDefId { + self.opt_local_def_id(hir_id).unwrap_or_else(|| { + bug!( + "local_def_id: no entry for `{:?}`, which has a map of `{:?}`", + hir_id, + self.find_entry(hir_id) + ) + }) + } + + #[inline] + pub fn opt_local_def_id(&self, hir_id: HirId) -> Option<LocalDefId> { + self.tcx.definitions.opt_hir_id_to_local_def_id(hir_id) + } + + #[inline] + pub fn local_def_id_to_hir_id(&self, def_id: LocalDefId) -> HirId { + self.tcx.definitions.local_def_id_to_hir_id(def_id) + } + + #[inline] + pub fn opt_local_def_id_to_hir_id(&self, def_id: LocalDefId) -> Option<HirId> { + self.tcx.definitions.opt_local_def_id_to_hir_id(def_id) + } + + pub fn def_kind(&self, local_def_id: LocalDefId) -> DefKind { + // FIXME(eddyb) support `find` on the crate root. + if local_def_id.to_def_id().index == CRATE_DEF_INDEX { + return DefKind::Mod; + } + + let hir_id = self.local_def_id_to_hir_id(local_def_id); + match self.get(hir_id) { + Node::Item(item) => match item.kind { + ItemKind::Static(..) => DefKind::Static, + ItemKind::Const(..) => DefKind::Const, + ItemKind::Fn(..) => DefKind::Fn, + ItemKind::Mod(..) => DefKind::Mod, + ItemKind::OpaqueTy(..) => DefKind::OpaqueTy, + ItemKind::TyAlias(..) => DefKind::TyAlias, + ItemKind::Enum(..) => DefKind::Enum, + ItemKind::Struct(..) => DefKind::Struct, + ItemKind::Union(..) => DefKind::Union, + ItemKind::Trait(..) => DefKind::Trait, + ItemKind::TraitAlias(..) => DefKind::TraitAlias, + ItemKind::ExternCrate(_) => DefKind::ExternCrate, + ItemKind::Use(..) => DefKind::Use, + ItemKind::ForeignMod(..) => DefKind::ForeignMod, + ItemKind::GlobalAsm(..) => DefKind::GlobalAsm, + ItemKind::Impl { .. } => DefKind::Impl, + }, + Node::ForeignItem(item) => match item.kind { + ForeignItemKind::Fn(..) => DefKind::Fn, + ForeignItemKind::Static(..) => DefKind::Static, + ForeignItemKind::Type => DefKind::ForeignTy, + }, + Node::TraitItem(item) => match item.kind { + TraitItemKind::Const(..) => DefKind::AssocConst, + TraitItemKind::Fn(..) => DefKind::AssocFn, + TraitItemKind::Type(..) => DefKind::AssocTy, + }, + Node::ImplItem(item) => match item.kind { + ImplItemKind::Const(..) => DefKind::AssocConst, + ImplItemKind::Fn(..) => DefKind::AssocFn, + ImplItemKind::TyAlias(..) => DefKind::AssocTy, + }, + Node::Variant(_) => DefKind::Variant, + Node::Ctor(variant_data) => { + // FIXME(eddyb) is this even possible, if we have a `Node::Ctor`? + assert_ne!(variant_data.ctor_hir_id(), None); + + let ctor_of = match self.find(self.get_parent_node(hir_id)) { + Some(Node::Item(..)) => def::CtorOf::Struct, + Some(Node::Variant(..)) => def::CtorOf::Variant, + _ => unreachable!(), + }; + DefKind::Ctor(ctor_of, def::CtorKind::from_hir(variant_data)) + } + Node::AnonConst(_) => DefKind::AnonConst, + Node::Field(_) => DefKind::Field, + Node::Expr(expr) => match expr.kind { + ExprKind::Closure(.., None) => DefKind::Closure, + ExprKind::Closure(.., Some(_)) => DefKind::Generator, + _ => bug!("def_kind: unsupported node: {}", self.node_to_string(hir_id)), + }, + Node::MacroDef(_) => DefKind::Macro(MacroKind::Bang), + Node::GenericParam(param) => match param.kind { + GenericParamKind::Lifetime { .. } => DefKind::LifetimeParam, + GenericParamKind::Type { .. } => DefKind::TyParam, + GenericParamKind::Const { .. } => DefKind::ConstParam, + }, + Node::Stmt(_) + | Node::PathSegment(_) + | Node::Ty(_) + | Node::TraitRef(_) + | Node::Pat(_) + | Node::Binding(_) + | Node::Local(_) + | Node::Param(_) + | Node::Arm(_) + | Node::Lifetime(_) + | Node::Visibility(_) + | Node::Block(_) + | Node::Crate(_) => bug!("def_kind: unsupported node: {}", self.node_to_string(hir_id)), + } + } + + fn find_entry(&self, id: HirId) -> Option<Entry<'hir>> { + if id.local_id == ItemLocalId::from_u32(0) { + let owner = self.tcx.hir_owner(id.owner); + owner.map(|owner| Entry { parent: owner.parent, node: owner.node }) + } else { + let owner = self.tcx.hir_owner_nodes(id.owner); + owner.and_then(|owner| { + let node = owner.nodes[id.local_id].as_ref(); + // FIXME(eddyb) use a single generic type insted of having both + // `Entry` and `ParentedNode`, which are effectively the same. + // Alternatively, rewrite code using `Entry` to use `ParentedNode`. + node.map(|node| Entry { + parent: HirId { owner: id.owner, local_id: node.parent }, + node: node.node, + }) + }) + } + } + + fn get_entry(&self, id: HirId) -> Entry<'hir> { + self.find_entry(id).unwrap() + } + + pub fn item(&self, id: HirId) -> &'hir Item<'hir> { + match self.find(id).unwrap() { + Node::Item(item) => item, + _ => bug!(), + } + } + + pub fn trait_item(&self, id: TraitItemId) -> &'hir TraitItem<'hir> { + match self.find(id.hir_id).unwrap() { + Node::TraitItem(item) => item, + _ => bug!(), + } + } + + pub fn impl_item(&self, id: ImplItemId) -> &'hir ImplItem<'hir> { + match self.find(id.hir_id).unwrap() { + Node::ImplItem(item) => item, + _ => bug!(), + } + } + + pub fn body(&self, id: BodyId) -> &'hir Body<'hir> { + self.tcx.hir_owner_nodes(id.hir_id.owner).unwrap().bodies.get(&id.hir_id.local_id).unwrap() + } + + pub fn fn_decl_by_hir_id(&self, hir_id: HirId) -> Option<&'hir FnDecl<'hir>> { + if let Some(node) = self.find(hir_id) { + fn_decl(node) + } else { + bug!("no node for hir_id `{}`", hir_id) + } + } + + pub fn fn_sig_by_hir_id(&self, hir_id: HirId) -> Option<&'hir FnSig<'hir>> { + if let Some(node) = self.find(hir_id) { + fn_sig(node) + } else { + bug!("no node for hir_id `{}`", hir_id) + } + } + + pub fn enclosing_body_owner(&self, hir_id: HirId) -> HirId { + for (parent, _) in self.parent_iter(hir_id) { + if let Some(body) = self.maybe_body_owned_by(parent) { + return self.body_owner(body); + } + } + + bug!("no `enclosing_body_owner` for hir_id `{}`", hir_id); + } + + /// Returns the `HirId` that corresponds to the definition of + /// which this is the body of, i.e., a `fn`, `const` or `static` + /// item (possibly associated), a closure, or a `hir::AnonConst`. + pub fn body_owner(&self, BodyId { hir_id }: BodyId) -> HirId { + let parent = self.get_parent_node(hir_id); + assert!(self.find(parent).map_or(false, |n| is_body_owner(n, hir_id))); + parent + } + + pub fn body_owner_def_id(&self, id: BodyId) -> LocalDefId { + self.local_def_id(self.body_owner(id)) + } + + /// Given a `HirId`, returns the `BodyId` associated with it, + /// if the node is a body owner, otherwise returns `None`. + pub fn maybe_body_owned_by(&self, hir_id: HirId) -> Option<BodyId> { + self.find(hir_id).map(associated_body).flatten() + } + + /// Given a body owner's id, returns the `BodyId` associated with it. + pub fn body_owned_by(&self, id: HirId) -> BodyId { + self.maybe_body_owned_by(id).unwrap_or_else(|| { + span_bug!( + self.span(id), + "body_owned_by: {} has no associated body", + self.node_to_string(id) + ); + }) + } + + pub fn body_param_names(&self, id: BodyId) -> impl Iterator<Item = Ident> + 'hir { + self.body(id).params.iter().map(|arg| match arg.pat.kind { + PatKind::Binding(_, _, ident, _) => ident, + _ => Ident::new(kw::Invalid, rustc_span::DUMMY_SP), + }) + } + + /// Returns the `BodyOwnerKind` of this `LocalDefId`. + /// + /// Panics if `LocalDefId` does not have an associated body. + pub fn body_owner_kind(&self, id: HirId) -> BodyOwnerKind { + match self.get(id) { + Node::Item(&Item { kind: ItemKind::Const(..), .. }) + | Node::TraitItem(&TraitItem { kind: TraitItemKind::Const(..), .. }) + | Node::ImplItem(&ImplItem { kind: ImplItemKind::Const(..), .. }) + | Node::AnonConst(_) => BodyOwnerKind::Const, + Node::Ctor(..) + | Node::Item(&Item { kind: ItemKind::Fn(..), .. }) + | Node::TraitItem(&TraitItem { kind: TraitItemKind::Fn(..), .. }) + | Node::ImplItem(&ImplItem { kind: ImplItemKind::Fn(..), .. }) => BodyOwnerKind::Fn, + Node::Item(&Item { kind: ItemKind::Static(_, m, _), .. }) => BodyOwnerKind::Static(m), + Node::Expr(&Expr { kind: ExprKind::Closure(..), .. }) => BodyOwnerKind::Closure, + node => bug!("{:#?} is not a body node", node), + } + } + + /// Returns the `ConstContext` of the body associated with this `LocalDefId`. + /// + /// Panics if `LocalDefId` does not have an associated body. + pub fn body_const_context(&self, did: LocalDefId) -> Option<ConstContext> { + let hir_id = self.local_def_id_to_hir_id(did); + let ccx = match self.body_owner_kind(hir_id) { + BodyOwnerKind::Const => ConstContext::Const, + BodyOwnerKind::Static(mt) => ConstContext::Static(mt), + + BodyOwnerKind::Fn if self.tcx.is_constructor(did.to_def_id()) => return None, + BodyOwnerKind::Fn if self.tcx.is_const_fn_raw(did.to_def_id()) => ConstContext::ConstFn, + BodyOwnerKind::Fn | BodyOwnerKind::Closure => return None, + }; + + Some(ccx) + } + + pub fn ty_param_owner(&self, id: HirId) -> HirId { + match self.get(id) { + Node::Item(&Item { kind: ItemKind::Trait(..) | ItemKind::TraitAlias(..), .. }) => id, + Node::GenericParam(_) => self.get_parent_node(id), + _ => bug!("ty_param_owner: {} not a type parameter", self.node_to_string(id)), + } + } + + pub fn ty_param_name(&self, id: HirId) -> Symbol { + match self.get(id) { + Node::Item(&Item { kind: ItemKind::Trait(..) | ItemKind::TraitAlias(..), .. }) => { + kw::SelfUpper + } + Node::GenericParam(param) => param.name.ident().name, + _ => bug!("ty_param_name: {} not a type parameter", self.node_to_string(id)), + } + } + + pub fn trait_impls(&self, trait_did: DefId) -> &'hir [HirId] { + self.tcx.all_local_trait_impls(LOCAL_CRATE).get(&trait_did).map_or(&[], |xs| &xs[..]) + } + + /// Gets the attributes on the crate. This is preferable to + /// invoking `krate.attrs` because it registers a tighter + /// dep-graph access. + pub fn krate_attrs(&self) -> &'hir [ast::Attribute] { + match self.get_entry(CRATE_HIR_ID).node { + Node::Crate(item) => item.attrs, + _ => bug!(), + } + } + + pub fn get_module(&self, module: LocalDefId) -> (&'hir Mod<'hir>, Span, HirId) { + let hir_id = self.local_def_id_to_hir_id(module); + match self.get_entry(hir_id).node { + Node::Item(&Item { span, kind: ItemKind::Mod(ref m), .. }) => (m, span, hir_id), + Node::Crate(item) => (&item.module, item.span, hir_id), + node => panic!("not a module: {:?}", node), + } + } + + pub fn visit_item_likes_in_module<V>(&self, module: LocalDefId, visitor: &mut V) + where + V: ItemLikeVisitor<'hir>, + { + let module = self.tcx.hir_module_items(module); + + for id in &module.items { + visitor.visit_item(self.expect_item(*id)); + } + + for id in &module.trait_items { + visitor.visit_trait_item(self.expect_trait_item(id.hir_id)); + } + + for id in &module.impl_items { + visitor.visit_impl_item(self.expect_impl_item(id.hir_id)); + } + } + + /// Retrieves the `Node` corresponding to `id`, panicking if it cannot be found. + pub fn get(&self, id: HirId) -> Node<'hir> { + self.find(id).unwrap_or_else(|| bug!("couldn't find hir id {} in the HIR map", id)) + } + + pub fn get_if_local(&self, id: DefId) -> Option<Node<'hir>> { + id.as_local().map(|id| self.get(self.local_def_id_to_hir_id(id))) + } + + pub fn get_generics(&self, id: DefId) -> Option<&'hir Generics<'hir>> { + self.get_if_local(id).and_then(|node| match &node { + Node::ImplItem(impl_item) => Some(&impl_item.generics), + Node::TraitItem(trait_item) => Some(&trait_item.generics), + Node::Item(Item { + kind: + ItemKind::Fn(_, generics, _) + | ItemKind::TyAlias(_, generics) + | ItemKind::Enum(_, generics) + | ItemKind::Struct(_, generics) + | ItemKind::Union(_, generics) + | ItemKind::Trait(_, _, generics, ..) + | ItemKind::TraitAlias(generics, _) + | ItemKind::Impl { generics, .. }, + .. + }) => Some(generics), + _ => None, + }) + } + + /// Retrieves the `Node` corresponding to `id`, returning `None` if cannot be found. + pub fn find(&self, hir_id: HirId) -> Option<Node<'hir>> { + self.find_entry(hir_id).and_then(|entry| { + if let Node::Crate(..) = entry.node { None } else { Some(entry.node) } + }) + } + + /// Similar to `get_parent`; returns the parent HIR Id, or just `hir_id` if there + /// is no parent. Note that the parent may be `CRATE_HIR_ID`, which is not itself + /// present in the map, so passing the return value of `get_parent_node` to + /// `get` may in fact panic. + /// This function returns the immediate parent in the HIR, whereas `get_parent` + /// returns the enclosing item. Note that this might not be the actual parent + /// node in the HIR -- some kinds of nodes are not in the map and these will + /// never appear as the parent node. Thus, you can always walk the parent nodes + /// from a node to the root of the HIR (unless you get back the same ID here, + /// which can happen if the ID is not in the map itself or is just weird). + pub fn get_parent_node(&self, hir_id: HirId) -> HirId { + self.get_entry(hir_id).parent_node().unwrap_or(hir_id) + } + + /// Returns an iterator for the nodes in the ancestor tree of the `current_id` + /// until the crate root is reached. Prefer this over your own loop using `get_parent_node`. + pub fn parent_iter(&self, current_id: HirId) -> ParentHirIterator<'_, 'hir> { + ParentHirIterator { current_id, map: self } + } + + /// Checks if the node is an argument. An argument is a local variable whose + /// immediate parent is an item or a closure. + pub fn is_argument(&self, id: HirId) -> bool { + match self.find(id) { + Some(Node::Binding(_)) => (), + _ => return false, + } + match self.find(self.get_parent_node(id)) { + Some( + Node::Item(_) + | Node::TraitItem(_) + | Node::ImplItem(_) + | Node::Expr(Expr { kind: ExprKind::Closure(..), .. }), + ) => true, + _ => false, + } + } + + /// Whether the expression pointed at by `hir_id` belongs to a `const` evaluation context. + /// Used exclusively for diagnostics, to avoid suggestion function calls. + pub fn is_inside_const_context(&self, hir_id: HirId) -> bool { + self.body_const_context(self.local_def_id(self.enclosing_body_owner(hir_id))).is_some() + } + + /// Whether `hir_id` corresponds to a `mod` or a crate. + pub fn is_hir_id_module(&self, hir_id: HirId) -> bool { + match self.get_entry(hir_id).node { + Node::Item(Item { kind: ItemKind::Mod(_), .. }) | Node::Crate(..) => true, + _ => false, + } + } + + /// Retrieves the `HirId` for `id`'s enclosing method, unless there's a + /// `while` or `loop` before reaching it, as block tail returns are not + /// available in them. + /// + /// ``` + /// fn foo(x: usize) -> bool { + /// if x == 1 { + /// true // If `get_return_block` gets passed the `id` corresponding + /// } else { // to this, it will return `foo`'s `HirId`. + /// false + /// } + /// } + /// ``` + /// + /// ``` + /// fn foo(x: usize) -> bool { + /// loop { + /// true // If `get_return_block` gets passed the `id` corresponding + /// } // to this, it will return `None`. + /// false + /// } + /// ``` + pub fn get_return_block(&self, id: HirId) -> Option<HirId> { + let mut iter = self.parent_iter(id).peekable(); + let mut ignore_tail = false; + if let Some(entry) = self.find_entry(id) { + if let Node::Expr(Expr { kind: ExprKind::Ret(_), .. }) = entry.node { + // When dealing with `return` statements, we don't care about climbing only tail + // expressions. + ignore_tail = true; + } + } + while let Some((hir_id, node)) = iter.next() { + if let (Some((_, next_node)), false) = (iter.peek(), ignore_tail) { + match next_node { + Node::Block(Block { expr: None, .. }) => return None, + // The current node is not the tail expression of its parent. + Node::Block(Block { expr: Some(e), .. }) if hir_id != e.hir_id => return None, + _ => {} + } + } + match node { + Node::Item(_) + | Node::ForeignItem(_) + | Node::TraitItem(_) + | Node::Expr(Expr { kind: ExprKind::Closure(..), .. }) + | Node::ImplItem(_) => return Some(hir_id), + // Ignore `return`s on the first iteration + Node::Expr(Expr { kind: ExprKind::Loop(..) | ExprKind::Ret(..), .. }) + | Node::Local(_) => { + return None; + } + _ => {} + } + } + None + } + + /// Retrieves the `HirId` for `id`'s parent item, or `id` itself if no + /// parent item is in this map. The "parent item" is the closest parent node + /// in the HIR which is recorded by the map and is an item, either an item + /// in a module, trait, or impl. + pub fn get_parent_item(&self, hir_id: HirId) -> HirId { + for (hir_id, node) in self.parent_iter(hir_id) { + match node { + Node::Crate(_) + | Node::Item(_) + | Node::ForeignItem(_) + | Node::TraitItem(_) + | Node::ImplItem(_) => return hir_id, + _ => {} + } + } + hir_id + } + + /// Returns the `HirId` of `id`'s nearest module parent, or `id` itself if no + /// module parent is in this map. + pub(super) fn get_module_parent_node(&self, hir_id: HirId) -> HirId { + for (hir_id, node) in self.parent_iter(hir_id) { + if let Node::Item(&Item { kind: ItemKind::Mod(_), .. }) = node { + return hir_id; + } + } + CRATE_HIR_ID + } + + /// When on a match arm tail expression or on a match arm, give back the enclosing `match` + /// expression. + /// + /// Used by error reporting when there's a type error in a match arm caused by the `match` + /// expression needing to be unit. + pub fn get_match_if_cause(&self, hir_id: HirId) -> Option<&'hir Expr<'hir>> { + for (_, node) in self.parent_iter(hir_id) { + match node { + Node::Item(_) + | Node::ForeignItem(_) + | Node::TraitItem(_) + | Node::ImplItem(_) + | Node::Stmt(Stmt { kind: StmtKind::Local(_), .. }) => break, + Node::Expr(expr @ Expr { kind: ExprKind::Match(..), .. }) => return Some(expr), + _ => {} + } + } + None + } + + /// Returns the nearest enclosing scope. A scope is roughly an item or block. + pub fn get_enclosing_scope(&self, hir_id: HirId) -> Option<HirId> { + for (hir_id, node) in self.parent_iter(hir_id) { + if let Node::Item(Item { + kind: + ItemKind::Fn(..) + | ItemKind::Const(..) + | ItemKind::Static(..) + | ItemKind::Mod(..) + | ItemKind::Enum(..) + | ItemKind::Struct(..) + | ItemKind::Union(..) + | ItemKind::Trait(..) + | ItemKind::Impl { .. }, + .. + }) + | Node::ForeignItem(ForeignItem { kind: ForeignItemKind::Fn(..), .. }) + | Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(..), .. }) + | Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(..), .. }) + | Node::Block(_) = node + { + return Some(hir_id); + } + } + None + } + + /// Returns the defining scope for an opaque type definition. + pub fn get_defining_scope(&self, id: HirId) -> HirId { + let mut scope = id; + loop { + scope = self.get_enclosing_scope(scope).unwrap_or(CRATE_HIR_ID); + if scope == CRATE_HIR_ID { + return CRATE_HIR_ID; + } + match self.get(scope) { + Node::Block(_) => {} + _ => break, + } + } + scope + } + + pub fn get_parent_did(&self, id: HirId) -> LocalDefId { + self.local_def_id(self.get_parent_item(id)) + } + + pub fn get_foreign_abi(&self, hir_id: HirId) -> Abi { + let parent = self.get_parent_item(hir_id); + if let Some(entry) = self.find_entry(parent) { + if let Entry { + node: Node::Item(Item { kind: ItemKind::ForeignMod(ref nm), .. }), .. + } = entry + { + return nm.abi; + } + } + bug!("expected foreign mod or inlined parent, found {}", self.node_to_string(parent)) + } + + pub fn expect_item(&self, id: HirId) -> &'hir Item<'hir> { + match self.find(id) { + Some(Node::Item(item)) => item, + _ => bug!("expected item, found {}", self.node_to_string(id)), + } + } + + pub fn expect_impl_item(&self, id: HirId) -> &'hir ImplItem<'hir> { + match self.find(id) { + Some(Node::ImplItem(item)) => item, + _ => bug!("expected impl item, found {}", self.node_to_string(id)), + } + } + + pub fn expect_trait_item(&self, id: HirId) -> &'hir TraitItem<'hir> { + match self.find(id) { + Some(Node::TraitItem(item)) => item, + _ => bug!("expected trait item, found {}", self.node_to_string(id)), + } + } + + pub fn expect_variant_data(&self, id: HirId) -> &'hir VariantData<'hir> { + match self.find(id) { + Some( + Node::Ctor(vd) + | Node::Item(Item { kind: ItemKind::Struct(vd, _) | ItemKind::Union(vd, _), .. }), + ) => vd, + Some(Node::Variant(variant)) => &variant.data, + _ => bug!("expected struct or variant, found {}", self.node_to_string(id)), + } + } + + pub fn expect_variant(&self, id: HirId) -> &'hir Variant<'hir> { + match self.find(id) { + Some(Node::Variant(variant)) => variant, + _ => bug!("expected variant, found {}", self.node_to_string(id)), + } + } + + pub fn expect_foreign_item(&self, id: HirId) -> &'hir ForeignItem<'hir> { + match self.find(id) { + Some(Node::ForeignItem(item)) => item, + _ => bug!("expected foreign item, found {}", self.node_to_string(id)), + } + } + + pub fn expect_expr(&self, id: HirId) -> &'hir Expr<'hir> { + match self.find(id) { + Some(Node::Expr(expr)) => expr, + _ => bug!("expected expr, found {}", self.node_to_string(id)), + } + } + + pub fn opt_name(&self, id: HirId) -> Option<Symbol> { + Some(match self.get(id) { + Node::Item(i) => i.ident.name, + Node::ForeignItem(fi) => fi.ident.name, + Node::ImplItem(ii) => ii.ident.name, + Node::TraitItem(ti) => ti.ident.name, + Node::Variant(v) => v.ident.name, + Node::Field(f) => f.ident.name, + Node::Lifetime(lt) => lt.name.ident().name, + Node::GenericParam(param) => param.name.ident().name, + Node::Binding(&Pat { kind: PatKind::Binding(_, _, l, _), .. }) => l.name, + Node::Ctor(..) => self.name(self.get_parent_item(id)), + _ => return None, + }) + } + + pub fn name(&self, id: HirId) -> Symbol { + match self.opt_name(id) { + Some(name) => name, + None => bug!("no name for {}", self.node_to_string(id)), + } + } + + /// Given a node ID, gets a list of attributes associated with the AST + /// corresponding to the node-ID. + pub fn attrs(&self, id: HirId) -> &'hir [ast::Attribute] { + let attrs = match self.find_entry(id).map(|entry| entry.node) { + Some(Node::Param(a)) => Some(&a.attrs[..]), + Some(Node::Local(l)) => Some(&l.attrs[..]), + Some(Node::Item(i)) => Some(&i.attrs[..]), + Some(Node::ForeignItem(fi)) => Some(&fi.attrs[..]), + Some(Node::TraitItem(ref ti)) => Some(&ti.attrs[..]), + Some(Node::ImplItem(ref ii)) => Some(&ii.attrs[..]), + Some(Node::Variant(ref v)) => Some(&v.attrs[..]), + Some(Node::Field(ref f)) => Some(&f.attrs[..]), + Some(Node::Expr(ref e)) => Some(&*e.attrs), + Some(Node::Stmt(ref s)) => Some(s.kind.attrs()), + Some(Node::Arm(ref a)) => Some(&*a.attrs), + Some(Node::GenericParam(param)) => Some(¶m.attrs[..]), + // Unit/tuple structs/variants take the attributes straight from + // the struct/variant definition. + Some(Node::Ctor(..)) => return self.attrs(self.get_parent_item(id)), + Some(Node::Crate(item)) => Some(&item.attrs[..]), + _ => None, + }; + attrs.unwrap_or(&[]) + } + + /// Gets the span of the definition of the specified HIR node. + /// This is used by `tcx.get_span` + pub fn span(&self, hir_id: HirId) -> Span { + match self.find_entry(hir_id).map(|entry| entry.node) { + Some(Node::Param(param)) => param.span, + Some(Node::Item(item)) => match &item.kind { + ItemKind::Fn(sig, _, _) => sig.span, + _ => item.span, + }, + Some(Node::ForeignItem(foreign_item)) => foreign_item.span, + Some(Node::TraitItem(trait_item)) => match &trait_item.kind { + TraitItemKind::Fn(sig, _) => sig.span, + _ => trait_item.span, + }, + Some(Node::ImplItem(impl_item)) => match &impl_item.kind { + ImplItemKind::Fn(sig, _) => sig.span, + _ => impl_item.span, + }, + Some(Node::Variant(variant)) => variant.span, + Some(Node::Field(field)) => field.span, + Some(Node::AnonConst(constant)) => self.body(constant.body).value.span, + Some(Node::Expr(expr)) => expr.span, + Some(Node::Stmt(stmt)) => stmt.span, + Some(Node::PathSegment(seg)) => seg.ident.span, + Some(Node::Ty(ty)) => ty.span, + Some(Node::TraitRef(tr)) => tr.path.span, + Some(Node::Binding(pat)) => pat.span, + Some(Node::Pat(pat)) => pat.span, + Some(Node::Arm(arm)) => arm.span, + Some(Node::Block(block)) => block.span, + Some(Node::Ctor(..)) => match self.find(self.get_parent_node(hir_id)) { + Some(Node::Item(item)) => item.span, + Some(Node::Variant(variant)) => variant.span, + _ => unreachable!(), + }, + Some(Node::Lifetime(lifetime)) => lifetime.span, + Some(Node::GenericParam(param)) => param.span, + Some(Node::Visibility(&Spanned { + node: VisibilityKind::Restricted { ref path, .. }, + .. + })) => path.span, + Some(Node::Visibility(v)) => bug!("unexpected Visibility {:?}", v), + Some(Node::Local(local)) => local.span, + Some(Node::MacroDef(macro_def)) => macro_def.span, + Some(Node::Crate(item)) => item.span, + None => bug!("hir::map::Map::span: id not in map: {:?}", hir_id), + } + } + + /// Like `hir.span()`, but includes the body of function items + /// (instead of just the function header) + pub fn span_with_body(&self, hir_id: HirId) -> Span { + match self.find_entry(hir_id).map(|entry| entry.node) { + Some(Node::TraitItem(item)) => item.span, + Some(Node::ImplItem(impl_item)) => impl_item.span, + Some(Node::Item(item)) => item.span, + Some(_) => self.span(hir_id), + _ => bug!("hir::map::Map::span_with_body: id not in map: {:?}", hir_id), + } + } + + pub fn span_if_local(&self, id: DefId) -> Option<Span> { + id.as_local().map(|id| self.span(self.local_def_id_to_hir_id(id))) + } + + pub fn res_span(&self, res: Res) -> Option<Span> { + match res { + Res::Err => None, + Res::Local(id) => Some(self.span(id)), + res => self.span_if_local(res.opt_def_id()?), + } + } + + /// Get a representation of this `id` for debugging purposes. + /// NOTE: Do NOT use this in diagnostics! + pub fn node_to_string(&self, id: HirId) -> String { + hir_id_to_string(self, id) + } +} + +impl<'hir> intravisit::Map<'hir> for Map<'hir> { + fn find(&self, hir_id: HirId) -> Option<Node<'hir>> { + self.find(hir_id) + } + + fn body(&self, id: BodyId) -> &'hir Body<'hir> { + self.body(id) + } + + fn item(&self, id: HirId) -> &'hir Item<'hir> { + self.item(id) + } + + fn trait_item(&self, id: TraitItemId) -> &'hir TraitItem<'hir> { + self.trait_item(id) + } + + fn impl_item(&self, id: ImplItemId) -> &'hir ImplItem<'hir> { + self.impl_item(id) + } +} + +trait Named { + fn name(&self) -> Symbol; +} + +impl<T: Named> Named for Spanned<T> { + fn name(&self) -> Symbol { + self.node.name() + } +} + +impl Named for Item<'_> { + fn name(&self) -> Symbol { + self.ident.name + } +} +impl Named for ForeignItem<'_> { + fn name(&self) -> Symbol { + self.ident.name + } +} +impl Named for Variant<'_> { + fn name(&self) -> Symbol { + self.ident.name + } +} +impl Named for StructField<'_> { + fn name(&self) -> Symbol { + self.ident.name + } +} +impl Named for TraitItem<'_> { + fn name(&self) -> Symbol { + self.ident.name + } +} +impl Named for ImplItem<'_> { + fn name(&self) -> Symbol { + self.ident.name + } +} + +pub(super) fn index_hir<'tcx>(tcx: TyCtxt<'tcx>, cnum: CrateNum) -> &'tcx IndexedHir<'tcx> { + assert_eq!(cnum, LOCAL_CRATE); + + let _prof_timer = tcx.sess.prof.generic_activity("build_hir_map"); + + let (map, crate_hash) = { + let hcx = tcx.create_stable_hashing_context(); + + let mut collector = + NodeCollector::root(tcx.sess, &**tcx.arena, tcx.untracked_crate, &tcx.definitions, hcx); + intravisit::walk_crate(&mut collector, tcx.untracked_crate); + + let crate_disambiguator = tcx.sess.local_crate_disambiguator(); + let cmdline_args = tcx.sess.opts.dep_tracking_hash(); + collector.finalize_and_compute_crate_hash(crate_disambiguator, &*tcx.cstore, cmdline_args) + }; + + tcx.arena.alloc(IndexedHir { crate_hash, map }) +} + +fn hir_id_to_string(map: &Map<'_>, id: HirId) -> String { + let id_str = format!(" (hir_id={})", id); + + let path_str = || { + // This functionality is used for debugging, try to use `TyCtxt` to get + // the user-friendly path, otherwise fall back to stringifying `DefPath`. + crate::ty::tls::with_opt(|tcx| { + if let Some(tcx) = tcx { + let def_id = map.local_def_id(id); + tcx.def_path_str(def_id.to_def_id()) + } else if let Some(path) = map.def_path_from_hir_id(id) { + path.data + .into_iter() + .map(|elem| elem.data.to_string()) + .collect::<Vec<_>>() + .join("::") + } else { + String::from("<missing path>") + } + }) + }; + + let span_str = || map.tcx.sess.source_map().span_to_snippet(map.span(id)).unwrap_or_default(); + let node_str = |prefix| format!("{} {}{}", prefix, span_str(), id_str); + + match map.find(id) { + Some(Node::Item(item)) => { + let item_str = match item.kind { + ItemKind::ExternCrate(..) => "extern crate", + ItemKind::Use(..) => "use", + ItemKind::Static(..) => "static", + ItemKind::Const(..) => "const", + ItemKind::Fn(..) => "fn", + ItemKind::Mod(..) => "mod", + ItemKind::ForeignMod(..) => "foreign mod", + ItemKind::GlobalAsm(..) => "global asm", + ItemKind::TyAlias(..) => "ty", + ItemKind::OpaqueTy(..) => "opaque type", + ItemKind::Enum(..) => "enum", + ItemKind::Struct(..) => "struct", + ItemKind::Union(..) => "union", + ItemKind::Trait(..) => "trait", + ItemKind::TraitAlias(..) => "trait alias", + ItemKind::Impl { .. } => "impl", + }; + format!("{} {}{}", item_str, path_str(), id_str) + } + Some(Node::ForeignItem(_)) => format!("foreign item {}{}", path_str(), id_str), + Some(Node::ImplItem(ii)) => match ii.kind { + ImplItemKind::Const(..) => { + format!("assoc const {} in {}{}", ii.ident, path_str(), id_str) + } + ImplItemKind::Fn(..) => format!("method {} in {}{}", ii.ident, path_str(), id_str), + ImplItemKind::TyAlias(_) => { + format!("assoc type {} in {}{}", ii.ident, path_str(), id_str) + } + }, + Some(Node::TraitItem(ti)) => { + let kind = match ti.kind { + TraitItemKind::Const(..) => "assoc constant", + TraitItemKind::Fn(..) => "trait method", + TraitItemKind::Type(..) => "assoc type", + }; + + format!("{} {} in {}{}", kind, ti.ident, path_str(), id_str) + } + Some(Node::Variant(ref variant)) => { + format!("variant {} in {}{}", variant.ident, path_str(), id_str) + } + Some(Node::Field(ref field)) => { + format!("field {} in {}{}", field.ident, path_str(), id_str) + } + Some(Node::AnonConst(_)) => node_str("const"), + Some(Node::Expr(_)) => node_str("expr"), + Some(Node::Stmt(_)) => node_str("stmt"), + Some(Node::PathSegment(_)) => node_str("path segment"), + Some(Node::Ty(_)) => node_str("type"), + Some(Node::TraitRef(_)) => node_str("trait ref"), + Some(Node::Binding(_)) => node_str("local"), + Some(Node::Pat(_)) => node_str("pat"), + Some(Node::Param(_)) => node_str("param"), + Some(Node::Arm(_)) => node_str("arm"), + Some(Node::Block(_)) => node_str("block"), + Some(Node::Local(_)) => node_str("local"), + Some(Node::Ctor(..)) => format!("ctor {}{}", path_str(), id_str), + Some(Node::Lifetime(_)) => node_str("lifetime"), + Some(Node::GenericParam(ref param)) => format!("generic_param {:?}{}", param, id_str), + Some(Node::Visibility(ref vis)) => format!("visibility {:?}{}", vis, id_str), + Some(Node::MacroDef(_)) => format!("macro {}{}", path_str(), id_str), + Some(Node::Crate(..)) => String::from("root_crate"), + None => format!("unknown node{}", id_str), + } +} + +pub fn provide(providers: &mut Providers) { + providers.def_kind = |tcx, def_id| tcx.hir().def_kind(def_id.expect_local()); +} diff --git a/compiler/rustc_middle/src/hir/mod.rs b/compiler/rustc_middle/src/hir/mod.rs new file mode 100644 index 00000000000..ae3b30217cc --- /dev/null +++ b/compiler/rustc_middle/src/hir/mod.rs @@ -0,0 +1,96 @@ +//! HIR datatypes. See the [rustc dev guide] for more info. +//! +//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html + +pub mod exports; +pub mod map; +pub mod place; + +use crate::ich::StableHashingContext; +use crate::ty::query::Providers; +use crate::ty::TyCtxt; +use rustc_data_structures::fingerprint::Fingerprint; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE}; +use rustc_hir::*; +use rustc_index::vec::IndexVec; + +pub struct Owner<'tcx> { + parent: HirId, + node: Node<'tcx>, +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Owner<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let Owner { parent, node } = self; + hcx.while_hashing_hir_bodies(false, |hcx| { + parent.hash_stable(hcx, hasher); + node.hash_stable(hcx, hasher); + }); + } +} + +#[derive(Clone)] +pub struct ParentedNode<'tcx> { + parent: ItemLocalId, + node: Node<'tcx>, +} + +pub struct OwnerNodes<'tcx> { + hash: Fingerprint, + nodes: IndexVec<ItemLocalId, Option<ParentedNode<'tcx>>>, + bodies: FxHashMap<ItemLocalId, &'tcx Body<'tcx>>, +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for OwnerNodes<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + // We ignore the `nodes` and `bodies` fields since these refer to information included in + // `hash` which is hashed in the collector and used for the crate hash. + let OwnerNodes { hash, nodes: _, bodies: _ } = *self; + hash.hash_stable(hcx, hasher); + } +} + +impl<'tcx> TyCtxt<'tcx> { + #[inline(always)] + pub fn hir(self) -> map::Map<'tcx> { + map::Map { tcx: self } + } + + pub fn parent_module(self, id: HirId) -> LocalDefId { + self.parent_module_from_def_id(id.owner) + } +} + +pub fn provide(providers: &mut Providers) { + providers.parent_module_from_def_id = |tcx, id| { + let hir = tcx.hir(); + hir.local_def_id(hir.get_module_parent_node(hir.local_def_id_to_hir_id(id))) + }; + providers.hir_crate = |tcx, _| tcx.untracked_crate; + providers.index_hir = map::index_hir; + providers.hir_module_items = |tcx, id| { + let hir = tcx.hir(); + let module = hir.local_def_id_to_hir_id(id); + &tcx.untracked_crate.modules[&module] + }; + providers.hir_owner = |tcx, id| tcx.index_hir(LOCAL_CRATE).map[id].signature; + providers.hir_owner_nodes = |tcx, id| tcx.index_hir(LOCAL_CRATE).map[id].with_bodies.as_deref(); + providers.fn_arg_names = |tcx, id| { + let hir = tcx.hir(); + let hir_id = hir.local_def_id_to_hir_id(id.expect_local()); + if let Some(body_id) = hir.maybe_body_owned_by(hir_id) { + tcx.arena.alloc_from_iter(hir.body_param_names(body_id)) + } else if let Node::TraitItem(&TraitItem { + kind: TraitItemKind::Fn(_, TraitFn::Required(idents)), + .. + }) = hir.get(hir_id) + { + tcx.arena.alloc_slice(idents) + } else { + span_bug!(hir.span(hir_id), "fn_arg_names: unexpected item {:?}", id); + } + }; + map::provide(providers); +} diff --git a/compiler/rustc_middle/src/hir/place.rs b/compiler/rustc_middle/src/hir/place.rs new file mode 100644 index 00000000000..bcb56fae170 --- /dev/null +++ b/compiler/rustc_middle/src/hir/place.rs @@ -0,0 +1,115 @@ +use crate::ty; +use crate::ty::Ty; + +use rustc_hir::HirId; +use rustc_target::abi::VariantIdx; + +#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)] +pub enum PlaceBase { + /// A temporary variable + Rvalue, + /// A named `static` item + StaticItem, + /// A named local variable + Local(HirId), + /// An upvar referenced by closure env + Upvar(ty::UpvarId), +} + +#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)] +pub enum ProjectionKind { + /// A dereference of a pointer, reference or `Box<T>` of the given type + Deref, + + /// `B.F` where `B` is the base expression and `F` is + /// the field. The field is identified by which variant + /// it appears in along with a field index. The variant + /// is used for enums. + Field(u32, VariantIdx), + + /// Some index like `B[x]`, where `B` is the base + /// expression. We don't preserve the index `x` because + /// we won't need it. + Index, + + /// A subslice covering a range of values like `B[x..y]`. + Subslice, +} + +#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)] +pub struct Projection<'tcx> { + /// Type after the projection is being applied. + pub ty: Ty<'tcx>, + + /// Defines the type of access + pub kind: ProjectionKind, +} + +/// A `Place` represents how a value is located in memory. +/// +/// This is an HIR version of `mir::Place` +#[derive(Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)] +pub struct Place<'tcx> { + /// The type of the `PlaceBase` + pub base_ty: Ty<'tcx>, + /// The "outermost" place that holds this value. + pub base: PlaceBase, + /// How this place is derived from the base place. + pub projections: Vec<Projection<'tcx>>, +} + +/// A `PlaceWithHirId` represents how a value is located in memory. +/// +/// This is an HIR version of `mir::Place` +#[derive(Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)] +pub struct PlaceWithHirId<'tcx> { + /// `HirId` of the expression or pattern producing this value. + pub hir_id: HirId, + + /// Information about the `Place` + pub place: Place<'tcx>, +} + +impl<'tcx> PlaceWithHirId<'tcx> { + pub fn new( + hir_id: HirId, + base_ty: Ty<'tcx>, + base: PlaceBase, + projections: Vec<Projection<'tcx>>, + ) -> PlaceWithHirId<'tcx> { + PlaceWithHirId { + hir_id: hir_id, + place: Place { base_ty: base_ty, base: base, projections: projections }, + } + } +} + +impl<'tcx> Place<'tcx> { + /// Returns an iterator of the types that have to be dereferenced to access + /// the `Place`. + /// + /// The types are in the reverse order that they are applied. So if + /// `x: &*const u32` and the `Place` is `**x`, then the types returned are + ///`*const u32` then `&*const u32`. + pub fn deref_tys(&self) -> impl Iterator<Item = Ty<'tcx>> + '_ { + self.projections.iter().enumerate().rev().filter_map(move |(index, proj)| { + if ProjectionKind::Deref == proj.kind { + Some(self.ty_before_projection(index)) + } else { + None + } + }) + } + + /// Returns the type of this `Place` after all projections have been applied. + pub fn ty(&self) -> Ty<'tcx> { + self.projections.last().map_or_else(|| self.base_ty, |proj| proj.ty) + } + + /// Returns the type of this `Place` immediately before `projection_index`th projection + /// is applied. + pub fn ty_before_projection(&self, projection_index: usize) -> Ty<'tcx> { + assert!(projection_index < self.projections.len()); + if projection_index == 0 { self.base_ty } else { self.projections[projection_index - 1].ty } + } +} diff --git a/compiler/rustc_middle/src/ich/hcx.rs b/compiler/rustc_middle/src/ich/hcx.rs new file mode 100644 index 00000000000..084fe4cfa16 --- /dev/null +++ b/compiler/rustc_middle/src/ich/hcx.rs @@ -0,0 +1,287 @@ +use crate::ich; +use crate::middle::cstore::CrateStore; +use crate::ty::{fast_reject, TyCtxt}; + +use rustc_ast as ast; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_data_structures::sync::Lrc; +use rustc_hir as hir; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_hir::definitions::{DefPathHash, Definitions}; +use rustc_session::Session; +use rustc_span::source_map::SourceMap; +use rustc_span::symbol::Symbol; +use rustc_span::{BytePos, CachingSourceMapView, SourceFile}; + +use rustc_span::def_id::{CrateNum, CRATE_DEF_INDEX}; +use smallvec::SmallVec; +use std::cmp::Ord; + +fn compute_ignored_attr_names() -> FxHashSet<Symbol> { + debug_assert!(!ich::IGNORED_ATTRIBUTES.is_empty()); + ich::IGNORED_ATTRIBUTES.iter().copied().collect() +} + +/// This is the context state available during incr. comp. hashing. It contains +/// enough information to transform `DefId`s and `HirId`s into stable `DefPath`s (i.e., +/// a reference to the `TyCtxt`) and it holds a few caches for speeding up various +/// things (e.g., each `DefId`/`DefPath` is only hashed once). +#[derive(Clone)] +pub struct StableHashingContext<'a> { + sess: &'a Session, + definitions: &'a Definitions, + cstore: &'a dyn CrateStore, + pub(super) body_resolver: BodyResolver<'a>, + hash_spans: bool, + hash_bodies: bool, + pub(super) node_id_hashing_mode: NodeIdHashingMode, + + // Very often, we are hashing something that does not need the + // `CachingSourceMapView`, so we initialize it lazily. + raw_source_map: &'a SourceMap, + caching_source_map: Option<CachingSourceMapView<'a>>, +} + +#[derive(PartialEq, Eq, Clone, Copy)] +pub enum NodeIdHashingMode { + Ignore, + HashDefPath, +} + +/// The `BodyResolver` allows mapping a `BodyId` to the corresponding `hir::Body`. +/// We could also just store a plain reference to the `hir::Crate` but we want +/// to avoid that the crate is used to get untracked access to all of the HIR. +#[derive(Clone, Copy)] +pub(super) struct BodyResolver<'tcx>(&'tcx hir::Crate<'tcx>); + +impl<'tcx> BodyResolver<'tcx> { + /// Returns a reference to the `hir::Body` with the given `BodyId`. + /// **Does not do any tracking**; use carefully. + pub(super) fn body(self, id: hir::BodyId) -> &'tcx hir::Body<'tcx> { + self.0.body(id) + } +} + +impl<'a> StableHashingContext<'a> { + /// The `krate` here is only used for mapping `BodyId`s to `Body`s. + /// Don't use it for anything else or you'll run the risk of + /// leaking data out of the tracking system. + #[inline] + fn new_with_or_without_spans( + sess: &'a Session, + krate: &'a hir::Crate<'a>, + definitions: &'a Definitions, + cstore: &'a dyn CrateStore, + always_ignore_spans: bool, + ) -> Self { + let hash_spans_initial = + !always_ignore_spans && !sess.opts.debugging_opts.incremental_ignore_spans; + + StableHashingContext { + sess, + body_resolver: BodyResolver(krate), + definitions, + cstore, + caching_source_map: None, + raw_source_map: sess.source_map(), + hash_spans: hash_spans_initial, + hash_bodies: true, + node_id_hashing_mode: NodeIdHashingMode::HashDefPath, + } + } + + #[inline] + pub fn new( + sess: &'a Session, + krate: &'a hir::Crate<'a>, + definitions: &'a Definitions, + cstore: &'a dyn CrateStore, + ) -> Self { + Self::new_with_or_without_spans( + sess, + krate, + definitions, + cstore, + /*always_ignore_spans=*/ false, + ) + } + + #[inline] + pub fn ignore_spans( + sess: &'a Session, + krate: &'a hir::Crate<'a>, + definitions: &'a Definitions, + cstore: &'a dyn CrateStore, + ) -> Self { + let always_ignore_spans = true; + Self::new_with_or_without_spans(sess, krate, definitions, cstore, always_ignore_spans) + } + + #[inline] + pub fn sess(&self) -> &'a Session { + self.sess + } + + #[inline] + pub fn while_hashing_hir_bodies<F: FnOnce(&mut Self)>(&mut self, hash_bodies: bool, f: F) { + let prev_hash_bodies = self.hash_bodies; + self.hash_bodies = hash_bodies; + f(self); + self.hash_bodies = prev_hash_bodies; + } + + #[inline] + pub fn while_hashing_spans<F: FnOnce(&mut Self)>(&mut self, hash_spans: bool, f: F) { + let prev_hash_spans = self.hash_spans; + self.hash_spans = hash_spans; + f(self); + self.hash_spans = prev_hash_spans; + } + + #[inline] + pub fn with_node_id_hashing_mode<F: FnOnce(&mut Self)>( + &mut self, + mode: NodeIdHashingMode, + f: F, + ) { + let prev = self.node_id_hashing_mode; + self.node_id_hashing_mode = mode; + f(self); + self.node_id_hashing_mode = prev; + } + + #[inline] + pub fn def_path_hash(&self, def_id: DefId) -> DefPathHash { + if let Some(def_id) = def_id.as_local() { + self.local_def_path_hash(def_id) + } else { + self.cstore.def_path_hash(def_id) + } + } + + #[inline] + pub fn local_def_path_hash(&self, def_id: LocalDefId) -> DefPathHash { + self.definitions.def_path_hash(def_id) + } + + #[inline] + pub fn hash_bodies(&self) -> bool { + self.hash_bodies + } + + #[inline] + pub fn source_map(&mut self) -> &mut CachingSourceMapView<'a> { + match self.caching_source_map { + Some(ref mut sm) => sm, + ref mut none => { + *none = Some(CachingSourceMapView::new(self.raw_source_map)); + none.as_mut().unwrap() + } + } + } + + #[inline] + pub fn is_ignored_attr(&self, name: Symbol) -> bool { + thread_local! { + static IGNORED_ATTRIBUTES: FxHashSet<Symbol> = compute_ignored_attr_names(); + } + IGNORED_ATTRIBUTES.with(|attrs| attrs.contains(&name)) + } +} + +/// Something that can provide a stable hashing context. +pub trait StableHashingContextProvider<'a> { + fn get_stable_hashing_context(&self) -> StableHashingContext<'a>; +} + +impl<'a, 'b, T: StableHashingContextProvider<'a>> StableHashingContextProvider<'a> for &'b T { + fn get_stable_hashing_context(&self) -> StableHashingContext<'a> { + (**self).get_stable_hashing_context() + } +} + +impl<'a, 'b, T: StableHashingContextProvider<'a>> StableHashingContextProvider<'a> for &'b mut T { + fn get_stable_hashing_context(&self) -> StableHashingContext<'a> { + (**self).get_stable_hashing_context() + } +} + +impl StableHashingContextProvider<'tcx> for TyCtxt<'tcx> { + fn get_stable_hashing_context(&self) -> StableHashingContext<'tcx> { + (*self).create_stable_hashing_context() + } +} + +impl<'a> StableHashingContextProvider<'a> for StableHashingContext<'a> { + fn get_stable_hashing_context(&self) -> StableHashingContext<'a> { + self.clone() + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for ast::NodeId { + fn hash_stable(&self, _: &mut StableHashingContext<'a>, _: &mut StableHasher) { + panic!("Node IDs should not appear in incremental state"); + } +} + +impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> { + fn hash_spans(&self) -> bool { + self.hash_spans + } + + #[inline] + fn hash_crate_num(&mut self, cnum: CrateNum, hasher: &mut StableHasher) { + let hcx = self; + hcx.def_path_hash(DefId { krate: cnum, index: CRATE_DEF_INDEX }).hash_stable(hcx, hasher); + } + + #[inline] + fn hash_def_id(&mut self, def_id: DefId, hasher: &mut StableHasher) { + let hcx = self; + hcx.def_path_hash(def_id).hash_stable(hcx, hasher); + } + + fn byte_pos_to_line_and_col( + &mut self, + byte: BytePos, + ) -> Option<(Lrc<SourceFile>, usize, BytePos)> { + self.source_map().byte_pos_to_line_and_col(byte) + } +} + +pub fn hash_stable_trait_impls<'a>( + hcx: &mut StableHashingContext<'a>, + hasher: &mut StableHasher, + blanket_impls: &[DefId], + non_blanket_impls: &FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>, +) { + { + let mut blanket_impls: SmallVec<[_; 8]> = + blanket_impls.iter().map(|&def_id| hcx.def_path_hash(def_id)).collect(); + + if blanket_impls.len() > 1 { + blanket_impls.sort_unstable(); + } + + blanket_impls.hash_stable(hcx, hasher); + } + + { + let mut keys: SmallVec<[_; 8]> = + non_blanket_impls.keys().map(|k| (k, k.map_def(|d| hcx.def_path_hash(d)))).collect(); + keys.sort_unstable_by(|&(_, ref k1), &(_, ref k2)| k1.cmp(k2)); + keys.len().hash_stable(hcx, hasher); + for (key, ref stable_key) in keys { + stable_key.hash_stable(hcx, hasher); + let mut impls: SmallVec<[_; 8]> = + non_blanket_impls[key].iter().map(|&impl_id| hcx.def_path_hash(impl_id)).collect(); + + if impls.len() > 1 { + impls.sort_unstable(); + } + + impls.hash_stable(hcx, hasher); + } + } +} diff --git a/compiler/rustc_middle/src/ich/impls_hir.rs b/compiler/rustc_middle/src/ich/impls_hir.rs new file mode 100644 index 00000000000..c2d177b69b6 --- /dev/null +++ b/compiler/rustc_middle/src/ich/impls_hir.rs @@ -0,0 +1,228 @@ +//! This module contains `HashStable` implementations for various HIR data +//! types in no particular order. + +use crate::ich::{NodeIdHashingMode, StableHashingContext}; +use rustc_attr as attr; +use rustc_data_structures::fingerprint::Fingerprint; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey}; +use rustc_hir as hir; +use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX}; +use rustc_hir::definitions::DefPathHash; +use smallvec::SmallVec; +use std::mem; + +impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> { + #[inline] + fn hash_hir_id(&mut self, hir_id: hir::HirId, hasher: &mut StableHasher) { + let hcx = self; + match hcx.node_id_hashing_mode { + NodeIdHashingMode::Ignore => { + // Don't do anything. + } + NodeIdHashingMode::HashDefPath => { + let hir::HirId { owner, local_id } = hir_id; + + hcx.local_def_path_hash(owner).hash_stable(hcx, hasher); + local_id.hash_stable(hcx, hasher); + } + } + } + + fn hash_body_id(&mut self, id: hir::BodyId, hasher: &mut StableHasher) { + let hcx = self; + if hcx.hash_bodies() { + hcx.body_resolver.body(id).hash_stable(hcx, hasher); + } + } + + fn hash_reference_to_item(&mut self, id: hir::HirId, hasher: &mut StableHasher) { + let hcx = self; + + hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { + id.hash_stable(hcx, hasher); + }) + } + + fn hash_hir_mod(&mut self, module: &hir::Mod<'_>, hasher: &mut StableHasher) { + let hcx = self; + let hir::Mod { inner: ref inner_span, ref item_ids } = *module; + + inner_span.hash_stable(hcx, hasher); + + // Combining the `DefPathHash`s directly is faster than feeding them + // into the hasher. Because we use a commutative combine, we also don't + // have to sort the array. + let item_ids_hash = item_ids + .iter() + .map(|id| { + let (def_path_hash, local_id) = id.id.to_stable_hash_key(hcx); + debug_assert_eq!(local_id, hir::ItemLocalId::from_u32(0)); + def_path_hash.0 + }) + .fold(Fingerprint::ZERO, |a, b| a.combine_commutative(b)); + + item_ids.len().hash_stable(hcx, hasher); + item_ids_hash.hash_stable(hcx, hasher); + } + + fn hash_hir_expr(&mut self, expr: &hir::Expr<'_>, hasher: &mut StableHasher) { + self.while_hashing_hir_bodies(true, |hcx| { + let hir::Expr { hir_id: _, ref span, ref kind, ref attrs } = *expr; + + span.hash_stable(hcx, hasher); + kind.hash_stable(hcx, hasher); + attrs.hash_stable(hcx, hasher); + }) + } + + fn hash_hir_ty(&mut self, ty: &hir::Ty<'_>, hasher: &mut StableHasher) { + self.while_hashing_hir_bodies(true, |hcx| { + let hir::Ty { hir_id: _, ref kind, ref span } = *ty; + + kind.hash_stable(hcx, hasher); + span.hash_stable(hcx, hasher); + }) + } + + fn hash_hir_visibility_kind( + &mut self, + vis: &hir::VisibilityKind<'_>, + hasher: &mut StableHasher, + ) { + let hcx = self; + mem::discriminant(vis).hash_stable(hcx, hasher); + match *vis { + hir::VisibilityKind::Public | hir::VisibilityKind::Inherited => { + // No fields to hash. + } + hir::VisibilityKind::Crate(sugar) => { + sugar.hash_stable(hcx, hasher); + } + hir::VisibilityKind::Restricted { ref path, hir_id } => { + hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { + hir_id.hash_stable(hcx, hasher); + }); + path.hash_stable(hcx, hasher); + } + } + } + + fn hash_hir_item_like<F: FnOnce(&mut Self)>(&mut self, f: F) { + let prev_hash_node_ids = self.node_id_hashing_mode; + self.node_id_hashing_mode = NodeIdHashingMode::Ignore; + + f(self); + + self.node_id_hashing_mode = prev_hash_node_ids; + } + + #[inline] + fn local_def_path_hash(&self, def_id: LocalDefId) -> DefPathHash { + self.local_def_path_hash(def_id) + } +} + +impl<'a> ToStableHashKey<StableHashingContext<'a>> for DefId { + type KeyType = DefPathHash; + + #[inline] + fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> DefPathHash { + hcx.def_path_hash(*self) + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for LocalDefId { + #[inline] + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + hcx.def_path_hash(self.to_def_id()).hash_stable(hcx, hasher); + } +} + +impl<'a> ToStableHashKey<StableHashingContext<'a>> for LocalDefId { + type KeyType = DefPathHash; + + #[inline] + fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> DefPathHash { + hcx.def_path_hash(self.to_def_id()) + } +} + +impl<'a> ToStableHashKey<StableHashingContext<'a>> for CrateNum { + type KeyType = DefPathHash; + + #[inline] + fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> DefPathHash { + let def_id = DefId { krate: *self, index: CRATE_DEF_INDEX }; + def_id.to_stable_hash_key(hcx) + } +} + +impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::ItemLocalId { + type KeyType = hir::ItemLocalId; + + #[inline] + fn to_stable_hash_key(&self, _: &StableHashingContext<'a>) -> hir::ItemLocalId { + *self + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for hir::Body<'_> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let hir::Body { params, value, generator_kind } = self; + + hcx.with_node_id_hashing_mode(NodeIdHashingMode::Ignore, |hcx| { + params.hash_stable(hcx, hasher); + value.hash_stable(hcx, hasher); + generator_kind.hash_stable(hcx, hasher); + }); + } +} + +impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::BodyId { + type KeyType = (DefPathHash, hir::ItemLocalId); + + #[inline] + fn to_stable_hash_key( + &self, + hcx: &StableHashingContext<'a>, + ) -> (DefPathHash, hir::ItemLocalId) { + let hir::BodyId { hir_id } = *self; + hir_id.to_stable_hash_key(hcx) + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for hir::TraitCandidate { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { + let hir::TraitCandidate { def_id, import_ids } = self; + + def_id.hash_stable(hcx, hasher); + import_ids.hash_stable(hcx, hasher); + }); + } +} + +impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::TraitCandidate { + type KeyType = (DefPathHash, SmallVec<[DefPathHash; 1]>); + + fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> Self::KeyType { + let hir::TraitCandidate { def_id, import_ids } = self; + + ( + hcx.def_path_hash(*def_id), + import_ids.iter().map(|def_id| hcx.local_def_path_hash(*def_id)).collect(), + ) + } +} + +impl<'hir> HashStable<StableHashingContext<'hir>> for attr::InlineAttr { + fn hash_stable(&self, hcx: &mut StableHashingContext<'hir>, hasher: &mut StableHasher) { + mem::discriminant(self).hash_stable(hcx, hasher); + } +} + +impl<'hir> HashStable<StableHashingContext<'hir>> for attr::OptimizeAttr { + fn hash_stable(&self, hcx: &mut StableHashingContext<'hir>, hasher: &mut StableHasher) { + mem::discriminant(self).hash_stable(hcx, hasher); + } +} diff --git a/compiler/rustc_middle/src/ich/impls_syntax.rs b/compiler/rustc_middle/src/ich/impls_syntax.rs new file mode 100644 index 00000000000..e3d4655831b --- /dev/null +++ b/compiler/rustc_middle/src/ich/impls_syntax.rs @@ -0,0 +1,149 @@ +//! This module contains `HashStable` implementations for various data types +//! from librustc_ast in no particular order. + +use crate::ich::StableHashingContext; + +use rustc_ast as ast; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_span::SourceFile; + +use smallvec::SmallVec; + +impl<'ctx> rustc_target::HashStableContext for StableHashingContext<'ctx> {} + +impl<'a> HashStable<StableHashingContext<'a>> for [ast::Attribute] { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + if self.is_empty() { + self.len().hash_stable(hcx, hasher); + return; + } + + // Some attributes are always ignored during hashing. + let filtered: SmallVec<[&ast::Attribute; 8]> = self + .iter() + .filter(|attr| { + !attr.is_doc_comment() + && !attr.ident().map_or(false, |ident| hcx.is_ignored_attr(ident.name)) + }) + .collect(); + + filtered.len().hash_stable(hcx, hasher); + for attr in filtered { + attr.hash_stable(hcx, hasher); + } + } +} + +impl<'ctx> rustc_ast::HashStableContext for StableHashingContext<'ctx> { + fn hash_attr(&mut self, attr: &ast::Attribute, hasher: &mut StableHasher) { + // Make sure that these have been filtered out. + debug_assert!(!attr.ident().map_or(false, |ident| self.is_ignored_attr(ident.name))); + debug_assert!(!attr.is_doc_comment()); + + let ast::Attribute { kind, id: _, style, span } = attr; + if let ast::AttrKind::Normal(item) = kind { + item.hash_stable(self, hasher); + style.hash_stable(self, hasher); + span.hash_stable(self, hasher); + } else { + unreachable!(); + } + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for SourceFile { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let SourceFile { + name: _, // We hash the smaller name_hash instead of this + name_hash, + name_was_remapped, + unmapped_path: _, + cnum, + // Do not hash the source as it is not encoded + src: _, + ref src_hash, + external_src: _, + start_pos, + end_pos: _, + ref lines, + ref multibyte_chars, + ref non_narrow_chars, + ref normalized_pos, + } = *self; + + (name_hash as u64).hash_stable(hcx, hasher); + name_was_remapped.hash_stable(hcx, hasher); + + src_hash.hash_stable(hcx, hasher); + + // We only hash the relative position within this source_file + lines.len().hash_stable(hcx, hasher); + for &line in lines.iter() { + stable_byte_pos(line, start_pos).hash_stable(hcx, hasher); + } + + // We only hash the relative position within this source_file + multibyte_chars.len().hash_stable(hcx, hasher); + for &char_pos in multibyte_chars.iter() { + stable_multibyte_char(char_pos, start_pos).hash_stable(hcx, hasher); + } + + non_narrow_chars.len().hash_stable(hcx, hasher); + for &char_pos in non_narrow_chars.iter() { + stable_non_narrow_char(char_pos, start_pos).hash_stable(hcx, hasher); + } + + normalized_pos.len().hash_stable(hcx, hasher); + for &char_pos in normalized_pos.iter() { + stable_normalized_pos(char_pos, start_pos).hash_stable(hcx, hasher); + } + + cnum.hash_stable(hcx, hasher); + } +} + +fn stable_byte_pos(pos: ::rustc_span::BytePos, source_file_start: ::rustc_span::BytePos) -> u32 { + pos.0 - source_file_start.0 +} + +fn stable_multibyte_char( + mbc: ::rustc_span::MultiByteChar, + source_file_start: ::rustc_span::BytePos, +) -> (u32, u32) { + let ::rustc_span::MultiByteChar { pos, bytes } = mbc; + + (pos.0 - source_file_start.0, bytes as u32) +} + +fn stable_non_narrow_char( + swc: ::rustc_span::NonNarrowChar, + source_file_start: ::rustc_span::BytePos, +) -> (u32, u32) { + let pos = swc.pos(); + let width = swc.width(); + + (pos.0 - source_file_start.0, width as u32) +} + +fn stable_normalized_pos( + np: ::rustc_span::NormalizedPos, + source_file_start: ::rustc_span::BytePos, +) -> (u32, u32) { + let ::rustc_span::NormalizedPos { pos, diff } = np; + + (pos.0 - source_file_start.0, diff) +} + +impl<'tcx> HashStable<StableHashingContext<'tcx>> for rustc_feature::Features { + fn hash_stable(&self, hcx: &mut StableHashingContext<'tcx>, hasher: &mut StableHasher) { + // Unfortunately we cannot exhaustively list fields here, since the + // struct is macro generated. + self.declared_lang_features.hash_stable(hcx, hasher); + self.declared_lib_features.hash_stable(hcx, hasher); + + self.walk_feature_fields(|feature_name, value| { + feature_name.hash_stable(hcx, hasher); + value.hash_stable(hcx, hasher); + }); + } +} diff --git a/compiler/rustc_middle/src/ich/impls_ty.rs b/compiler/rustc_middle/src/ich/impls_ty.rs new file mode 100644 index 00000000000..8f15c99f951 --- /dev/null +++ b/compiler/rustc_middle/src/ich/impls_ty.rs @@ -0,0 +1,204 @@ +//! This module contains `HashStable` implementations for various data types +//! from `rustc_middle::ty` in no particular order. + +use crate::ich::{NodeIdHashingMode, StableHashingContext}; +use crate::middle::region; +use crate::mir; +use crate::ty; +use rustc_data_structures::fingerprint::Fingerprint; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey}; +use std::cell::RefCell; +use std::mem; + +impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for &'tcx ty::List<T> +where + T: HashStable<StableHashingContext<'a>>, +{ + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + thread_local! { + static CACHE: RefCell<FxHashMap<(usize, usize), Fingerprint>> = + RefCell::new(Default::default()); + } + + let hash = CACHE.with(|cache| { + let key = (self.as_ptr() as usize, self.len()); + if let Some(&hash) = cache.borrow().get(&key) { + return hash; + } + + let mut hasher = StableHasher::new(); + (&self[..]).hash_stable(hcx, &mut hasher); + + let hash: Fingerprint = hasher.finish(); + cache.borrow_mut().insert(key, hash); + hash + }); + + hash.hash_stable(hcx, hasher); + } +} + +impl<'a, 'tcx, T> ToStableHashKey<StableHashingContext<'a>> for &'tcx ty::List<T> +where + T: HashStable<StableHashingContext<'a>>, +{ + type KeyType = Fingerprint; + + #[inline] + fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> Fingerprint { + let mut hasher = StableHasher::new(); + let mut hcx: StableHashingContext<'a> = hcx.clone(); + self.hash_stable(&mut hcx, &mut hasher); + hasher.finish() + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ty::subst::GenericArg<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + self.unpack().hash_stable(hcx, hasher); + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for ty::RegionKind { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + mem::discriminant(self).hash_stable(hcx, hasher); + match *self { + ty::ReErased | ty::ReStatic => { + // No variant fields to hash for these ... + } + ty::ReEmpty(universe) => { + universe.hash_stable(hcx, hasher); + } + ty::ReLateBound(db, ty::BrAnon(i)) => { + db.hash_stable(hcx, hasher); + i.hash_stable(hcx, hasher); + } + ty::ReLateBound(db, ty::BrNamed(def_id, name)) => { + db.hash_stable(hcx, hasher); + def_id.hash_stable(hcx, hasher); + name.hash_stable(hcx, hasher); + } + ty::ReLateBound(db, ty::BrEnv) => { + db.hash_stable(hcx, hasher); + } + ty::ReEarlyBound(ty::EarlyBoundRegion { def_id, index, name }) => { + def_id.hash_stable(hcx, hasher); + index.hash_stable(hcx, hasher); + name.hash_stable(hcx, hasher); + } + ty::ReFree(ref free_region) => { + free_region.hash_stable(hcx, hasher); + } + ty::ReVar(..) | ty::RePlaceholder(..) => { + bug!("StableHasher: unexpected region {:?}", *self) + } + } + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for ty::RegionVid { + #[inline] + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + self.index().hash_stable(hcx, hasher); + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ty::ConstVid<'tcx> { + #[inline] + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + self.index.hash_stable(hcx, hasher); + } +} + +impl<'tcx> HashStable<StableHashingContext<'tcx>> for ty::BoundVar { + #[inline] + fn hash_stable(&self, hcx: &mut StableHashingContext<'tcx>, hasher: &mut StableHasher) { + self.index().hash_stable(hcx, hasher); + } +} + +impl<'a, T> HashStable<StableHashingContext<'a>> for ty::Binder<T> +where + T: HashStable<StableHashingContext<'a>>, +{ + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + self.as_ref().skip_binder().hash_stable(hcx, hasher); + } +} + +// AllocIds get resolved to whatever they point to (to be stable) +impl<'a> HashStable<StableHashingContext<'a>> for mir::interpret::AllocId { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + ty::tls::with_opt(|tcx| { + trace!("hashing {:?}", *self); + let tcx = tcx.expect("can't hash AllocIds during hir lowering"); + tcx.get_global_alloc(*self).hash_stable(hcx, hasher); + }); + } +} + +// `Relocations` with default type parameters is a sorted map. +impl<'a, Tag> HashStable<StableHashingContext<'a>> for mir::interpret::Relocations<Tag> +where + Tag: HashStable<StableHashingContext<'a>>, +{ + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + self.len().hash_stable(hcx, hasher); + for reloc in self.iter() { + reloc.hash_stable(hcx, hasher); + } + } +} + +impl<'a> ToStableHashKey<StableHashingContext<'a>> for region::Scope { + type KeyType = region::Scope; + + #[inline] + fn to_stable_hash_key(&self, _: &StableHashingContext<'a>) -> region::Scope { + *self + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for ty::TyVid { + fn hash_stable(&self, _hcx: &mut StableHashingContext<'a>, _hasher: &mut StableHasher) { + // `TyVid` values are confined to an inference context and hence + // should not be hashed. + bug!("ty::TyKind::hash_stable() - can't hash a TyVid {:?}.", *self) + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for ty::IntVid { + fn hash_stable(&self, _hcx: &mut StableHashingContext<'a>, _hasher: &mut StableHasher) { + // `IntVid` values are confined to an inference context and hence + // should not be hashed. + bug!("ty::TyKind::hash_stable() - can't hash an IntVid {:?}.", *self) + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for ty::FloatVid { + fn hash_stable(&self, _hcx: &mut StableHashingContext<'a>, _hasher: &mut StableHasher) { + // `FloatVid` values are confined to an inference context and hence + // should not be hashed. + bug!("ty::TyKind::hash_stable() - can't hash a FloatVid {:?}.", *self) + } +} + +impl<'a, T> HashStable<StableHashingContext<'a>> for ty::steal::Steal<T> +where + T: HashStable<StableHashingContext<'a>>, +{ + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + self.borrow().hash_stable(hcx, hasher); + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for crate::middle::privacy::AccessLevels { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { + let crate::middle::privacy::AccessLevels { ref map } = *self; + + map.hash_stable(hcx, hasher); + }); + } +} diff --git a/compiler/rustc_middle/src/ich/mod.rs b/compiler/rustc_middle/src/ich/mod.rs new file mode 100644 index 00000000000..c8fb2bf39cc --- /dev/null +++ b/compiler/rustc_middle/src/ich/mod.rs @@ -0,0 +1,23 @@ +//! ICH - Incremental Compilation Hash + +pub use self::hcx::{ + hash_stable_trait_impls, NodeIdHashingMode, StableHashingContext, StableHashingContextProvider, +}; +use rustc_span::symbol::{sym, Symbol}; + +mod hcx; + +mod impls_hir; +mod impls_syntax; +mod impls_ty; + +pub const IGNORED_ATTRIBUTES: &[Symbol] = &[ + sym::cfg, + sym::rustc_if_this_changed, + sym::rustc_then_this_would_need, + sym::rustc_dirty, + sym::rustc_clean, + sym::rustc_partition_reused, + sym::rustc_partition_codegened, + sym::rustc_expected_cgu_reuse, +]; diff --git a/compiler/rustc_middle/src/infer/canonical.rs b/compiler/rustc_middle/src/infer/canonical.rs new file mode 100644 index 00000000000..1e15ae49a0c --- /dev/null +++ b/compiler/rustc_middle/src/infer/canonical.rs @@ -0,0 +1,354 @@ +//! **Canonicalization** is the key to constructing a query in the +//! middle of type inference. Ordinarily, it is not possible to store +//! types from type inference in query keys, because they contain +//! references to inference variables whose lifetimes are too short +//! and so forth. Canonicalizing a value T1 using `canonicalize_query` +//! produces two things: +//! +//! - a value T2 where each unbound inference variable has been +//! replaced with a **canonical variable**; +//! - a map M (of type `CanonicalVarValues`) from those canonical +//! variables back to the original. +//! +//! We can then do queries using T2. These will give back constraints +//! on the canonical variables which can be translated, using the map +//! M, into constraints in our source context. This process of +//! translating the results back is done by the +//! `instantiate_query_result` method. +//! +//! For a more detailed look at what is happening here, check +//! out the [chapter in the rustc dev guide][c]. +//! +//! [c]: https://rust-lang.github.io/chalk/book/canonical_queries/canonicalization.html + +use crate::infer::MemberConstraint; +use crate::ty::subst::GenericArg; +use crate::ty::{self, BoundVar, List, Region, TyCtxt}; +use rustc_index::vec::IndexVec; +use rustc_macros::HashStable; +use smallvec::SmallVec; +use std::ops::Index; + +/// A "canonicalized" type `V` is one where all free inference +/// variables have been rewritten to "canonical vars". These are +/// numbered starting from 0 in order of first appearance. +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyDecodable, TyEncodable)] +#[derive(HashStable, TypeFoldable, Lift)] +pub struct Canonical<'tcx, V> { + pub max_universe: ty::UniverseIndex, + pub variables: CanonicalVarInfos<'tcx>, + pub value: V, +} + +pub type CanonicalVarInfos<'tcx> = &'tcx List<CanonicalVarInfo>; + +/// A set of values corresponding to the canonical variables from some +/// `Canonical`. You can give these values to +/// `canonical_value.substitute` to substitute them into the canonical +/// value at the right places. +/// +/// When you canonicalize a value `V`, you get back one of these +/// vectors with the original values that were replaced by canonical +/// variables. You will need to supply it later to instantiate the +/// canonicalized query response. +#[derive(Clone, Debug, PartialEq, Eq, Hash, TyDecodable, TyEncodable)] +#[derive(HashStable, TypeFoldable, Lift)] +pub struct CanonicalVarValues<'tcx> { + pub var_values: IndexVec<BoundVar, GenericArg<'tcx>>, +} + +/// When we canonicalize a value to form a query, we wind up replacing +/// various parts of it with canonical variables. This struct stores +/// those replaced bits to remember for when we process the query +/// result. +#[derive(Clone, Debug)] +pub struct OriginalQueryValues<'tcx> { + /// Map from the universes that appear in the query to the + /// universes in the caller context. For the time being, we only + /// ever put ROOT values into the query, so this map is very + /// simple. + pub universe_map: SmallVec<[ty::UniverseIndex; 4]>, + + /// This is equivalent to `CanonicalVarValues`, but using a + /// `SmallVec` yields a significant performance win. + pub var_values: SmallVec<[GenericArg<'tcx>; 8]>, +} + +impl Default for OriginalQueryValues<'tcx> { + fn default() -> Self { + let mut universe_map = SmallVec::default(); + universe_map.push(ty::UniverseIndex::ROOT); + + Self { universe_map, var_values: SmallVec::default() } + } +} + +/// Information about a canonical variable that is included with the +/// canonical value. This is sufficient information for code to create +/// a copy of the canonical value in some other inference context, +/// with fresh inference variables replacing the canonical values. +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyDecodable, TyEncodable, HashStable)] +pub struct CanonicalVarInfo { + pub kind: CanonicalVarKind, +} + +impl CanonicalVarInfo { + pub fn universe(&self) -> ty::UniverseIndex { + self.kind.universe() + } + + pub fn is_existential(&self) -> bool { + match self.kind { + CanonicalVarKind::Ty(_) => true, + CanonicalVarKind::PlaceholderTy(_) => false, + CanonicalVarKind::Region(_) => true, + CanonicalVarKind::PlaceholderRegion(..) => false, + CanonicalVarKind::Const(_) => true, + CanonicalVarKind::PlaceholderConst(_) => false, + } + } +} + +/// Describes the "kind" of the canonical variable. This is a "kind" +/// in the type-theory sense of the term -- i.e., a "meta" type system +/// that analyzes type-like values. +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyDecodable, TyEncodable, HashStable)] +pub enum CanonicalVarKind { + /// Some kind of type inference variable. + Ty(CanonicalTyVarKind), + + /// A "placeholder" that represents "any type". + PlaceholderTy(ty::PlaceholderType), + + /// Region variable `'?R`. + Region(ty::UniverseIndex), + + /// A "placeholder" that represents "any region". Created when you + /// are solving a goal like `for<'a> T: Foo<'a>` to represent the + /// bound region `'a`. + PlaceholderRegion(ty::PlaceholderRegion), + + /// Some kind of const inference variable. + Const(ty::UniverseIndex), + + /// A "placeholder" that represents "any const". + PlaceholderConst(ty::PlaceholderConst), +} + +impl CanonicalVarKind { + pub fn universe(self) -> ty::UniverseIndex { + match self { + CanonicalVarKind::Ty(kind) => match kind { + CanonicalTyVarKind::General(ui) => ui, + CanonicalTyVarKind::Float | CanonicalTyVarKind::Int => ty::UniverseIndex::ROOT, + }, + + CanonicalVarKind::PlaceholderTy(placeholder) => placeholder.universe, + CanonicalVarKind::Region(ui) => ui, + CanonicalVarKind::PlaceholderRegion(placeholder) => placeholder.universe, + CanonicalVarKind::Const(ui) => ui, + CanonicalVarKind::PlaceholderConst(placeholder) => placeholder.universe, + } + } +} + +/// Rust actually has more than one category of type variables; +/// notably, the type variables we create for literals (e.g., 22 or +/// 22.) can only be instantiated with integral/float types (e.g., +/// usize or f32). In order to faithfully reproduce a type, we need to +/// know what set of types a given type variable can be unified with. +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyDecodable, TyEncodable, HashStable)] +pub enum CanonicalTyVarKind { + /// General type variable `?T` that can be unified with arbitrary types. + General(ty::UniverseIndex), + + /// Integral type variable `?I` (that can only be unified with integral types). + Int, + + /// Floating-point type variable `?F` (that can only be unified with float types). + Float, +} + +/// After we execute a query with a canonicalized key, we get back a +/// `Canonical<QueryResponse<..>>`. You can use +/// `instantiate_query_result` to access the data in this result. +#[derive(Clone, Debug, HashStable, TypeFoldable, Lift)] +pub struct QueryResponse<'tcx, R> { + pub var_values: CanonicalVarValues<'tcx>, + pub region_constraints: QueryRegionConstraints<'tcx>, + pub certainty: Certainty, + pub value: R, +} + +#[derive(Clone, Debug, Default, HashStable, TypeFoldable, Lift)] +pub struct QueryRegionConstraints<'tcx> { + pub outlives: Vec<QueryOutlivesConstraint<'tcx>>, + pub member_constraints: Vec<MemberConstraint<'tcx>>, +} + +impl QueryRegionConstraints<'_> { + /// Represents an empty (trivially true) set of region + /// constraints. + pub fn is_empty(&self) -> bool { + self.outlives.is_empty() && self.member_constraints.is_empty() + } +} + +pub type Canonicalized<'tcx, V> = Canonical<'tcx, V>; + +pub type CanonicalizedQueryResponse<'tcx, T> = &'tcx Canonical<'tcx, QueryResponse<'tcx, T>>; + +/// Indicates whether or not we were able to prove the query to be +/// true. +#[derive(Copy, Clone, Debug, HashStable)] +pub enum Certainty { + /// The query is known to be true, presuming that you apply the + /// given `var_values` and the region-constraints are satisfied. + Proven, + + /// The query is not known to be true, but also not known to be + /// false. The `var_values` represent *either* values that must + /// hold in order for the query to be true, or helpful tips that + /// *might* make it true. Currently rustc's trait solver cannot + /// distinguish the two (e.g., due to our preference for where + /// clauses over impls). + /// + /// After some unifiations and things have been done, it makes + /// sense to try and prove again -- of course, at that point, the + /// canonical form will be different, making this a distinct + /// query. + Ambiguous, +} + +impl Certainty { + pub fn is_proven(&self) -> bool { + match self { + Certainty::Proven => true, + Certainty::Ambiguous => false, + } + } + + pub fn is_ambiguous(&self) -> bool { + !self.is_proven() + } +} + +impl<'tcx, R> QueryResponse<'tcx, R> { + pub fn is_proven(&self) -> bool { + self.certainty.is_proven() + } + + pub fn is_ambiguous(&self) -> bool { + !self.is_proven() + } +} + +impl<'tcx, R> Canonical<'tcx, QueryResponse<'tcx, R>> { + pub fn is_proven(&self) -> bool { + self.value.is_proven() + } + + pub fn is_ambiguous(&self) -> bool { + !self.is_proven() + } +} + +impl<'tcx, V> Canonical<'tcx, V> { + /// Allows you to map the `value` of a canonical while keeping the + /// same set of bound variables. + /// + /// **WARNING:** This function is very easy to mis-use, hence the + /// name! In particular, the new value `W` must use all **the + /// same type/region variables** in **precisely the same order** + /// as the original! (The ordering is defined by the + /// `TypeFoldable` implementation of the type in question.) + /// + /// An example of a **correct** use of this: + /// + /// ```rust,ignore (not real code) + /// let a: Canonical<'_, T> = ...; + /// let b: Canonical<'_, (T,)> = a.unchecked_map(|v| (v, )); + /// ``` + /// + /// An example of an **incorrect** use of this: + /// + /// ```rust,ignore (not real code) + /// let a: Canonical<'tcx, T> = ...; + /// let ty: Ty<'tcx> = ...; + /// let b: Canonical<'tcx, (T, Ty<'tcx>)> = a.unchecked_map(|v| (v, ty)); + /// ``` + pub fn unchecked_map<W>(self, map_op: impl FnOnce(V) -> W) -> Canonical<'tcx, W> { + let Canonical { max_universe, variables, value } = self; + Canonical { max_universe, variables, value: map_op(value) } + } +} + +pub type QueryOutlivesConstraint<'tcx> = + ty::Binder<ty::OutlivesPredicate<GenericArg<'tcx>, Region<'tcx>>>; + +CloneTypeFoldableAndLiftImpls! { + crate::infer::canonical::Certainty, + crate::infer::canonical::CanonicalVarInfo, + crate::infer::canonical::CanonicalVarKind, +} + +CloneTypeFoldableImpls! { + for <'tcx> { + crate::infer::canonical::CanonicalVarInfos<'tcx>, + } +} + +impl<'tcx> CanonicalVarValues<'tcx> { + pub fn len(&self) -> usize { + self.var_values.len() + } + + /// Makes an identity substitution from this one: each bound var + /// is matched to the same bound var, preserving the original kinds. + /// For example, if we have: + /// `self.var_values == [Type(u32), Lifetime('a), Type(u64)]` + /// we'll return a substitution `subst` with: + /// `subst.var_values == [Type(^0), Lifetime(^1), Type(^2)]`. + pub fn make_identity(&self, tcx: TyCtxt<'tcx>) -> Self { + use crate::ty::subst::GenericArgKind; + + CanonicalVarValues { + var_values: self + .var_values + .iter() + .zip(0..) + .map(|(kind, i)| match kind.unpack() { + GenericArgKind::Type(..) => { + tcx.mk_ty(ty::Bound(ty::INNERMOST, ty::BoundVar::from_u32(i).into())).into() + } + GenericArgKind::Lifetime(..) => tcx + .mk_region(ty::ReLateBound(ty::INNERMOST, ty::BoundRegion::BrAnon(i))) + .into(), + GenericArgKind::Const(ct) => tcx + .mk_const(ty::Const { + ty: ct.ty, + val: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from_u32(i)), + }) + .into(), + }) + .collect(), + } + } +} + +impl<'a, 'tcx> IntoIterator for &'a CanonicalVarValues<'tcx> { + type Item = GenericArg<'tcx>; + type IntoIter = ::std::iter::Cloned<::std::slice::Iter<'a, GenericArg<'tcx>>>; + + fn into_iter(self) -> Self::IntoIter { + self.var_values.iter().cloned() + } +} + +impl<'tcx> Index<BoundVar> for CanonicalVarValues<'tcx> { + type Output = GenericArg<'tcx>; + + fn index(&self, value: BoundVar) -> &GenericArg<'tcx> { + &self.var_values[value] + } +} diff --git a/compiler/rustc_middle/src/infer/mod.rs b/compiler/rustc_middle/src/infer/mod.rs new file mode 100644 index 00000000000..497d3811f28 --- /dev/null +++ b/compiler/rustc_middle/src/infer/mod.rs @@ -0,0 +1,32 @@ +pub mod canonical; +pub mod unify_key; + +use crate::ty::Region; +use crate::ty::Ty; +use rustc_data_structures::sync::Lrc; +use rustc_hir::def_id::DefId; +use rustc_span::Span; + +/// Requires that `region` must be equal to one of the regions in `choice_regions`. +/// We often denote this using the syntax: +/// +/// ``` +/// R0 member of [O1..On] +/// ``` +#[derive(Debug, Clone, HashStable, TypeFoldable, Lift)] +pub struct MemberConstraint<'tcx> { + /// The `DefId` of the opaque type causing this constraint: used for error reporting. + pub opaque_type_def_id: DefId, + + /// The span where the hidden type was instantiated. + pub definition_span: Span, + + /// The hidden type in which `member_region` appears: used for error reporting. + pub hidden_ty: Ty<'tcx>, + + /// The region `R0`. + pub member_region: Region<'tcx>, + + /// The options `O1..On`. + pub choice_regions: Lrc<Vec<Region<'tcx>>>, +} diff --git a/compiler/rustc_middle/src/infer/unify_key.rs b/compiler/rustc_middle/src/infer/unify_key.rs new file mode 100644 index 00000000000..2580ac6bebd --- /dev/null +++ b/compiler/rustc_middle/src/infer/unify_key.rs @@ -0,0 +1,234 @@ +use crate::ty::{self, FloatVarValue, InferConst, IntVarValue, Ty, TyCtxt}; +use rustc_data_structures::snapshot_vec; +use rustc_data_structures::undo_log::UndoLogs; +use rustc_data_structures::unify::{ + self, EqUnifyValue, InPlace, NoError, UnificationTable, UnifyKey, UnifyValue, +}; +use rustc_span::symbol::Symbol; +use rustc_span::{Span, DUMMY_SP}; + +use std::cmp; +use std::marker::PhantomData; + +pub trait ToType { + fn to_type<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx>; +} + +/// Raw `TyVid` are used as the unification key for `sub_relations`; +/// they carry no values. +impl UnifyKey for ty::TyVid { + type Value = (); + fn index(&self) -> u32 { + self.index + } + fn from_index(i: u32) -> ty::TyVid { + ty::TyVid { index: i } + } + fn tag() -> &'static str { + "TyVid" + } +} + +impl UnifyKey for ty::IntVid { + type Value = Option<IntVarValue>; + fn index(&self) -> u32 { + self.index + } + fn from_index(i: u32) -> ty::IntVid { + ty::IntVid { index: i } + } + fn tag() -> &'static str { + "IntVid" + } +} + +impl EqUnifyValue for IntVarValue {} + +#[derive(PartialEq, Copy, Clone, Debug)] +pub struct RegionVidKey { + /// The minimum region vid in the unification set. This is needed + /// to have a canonical name for a type to prevent infinite + /// recursion. + pub min_vid: ty::RegionVid, +} + +impl UnifyValue for RegionVidKey { + type Error = NoError; + + fn unify_values(value1: &Self, value2: &Self) -> Result<Self, NoError> { + let min_vid = if value1.min_vid.index() < value2.min_vid.index() { + value1.min_vid + } else { + value2.min_vid + }; + + Ok(RegionVidKey { min_vid }) + } +} + +impl UnifyKey for ty::RegionVid { + type Value = RegionVidKey; + fn index(&self) -> u32 { + u32::from(*self) + } + fn from_index(i: u32) -> ty::RegionVid { + ty::RegionVid::from(i) + } + fn tag() -> &'static str { + "RegionVid" + } +} + +impl ToType for IntVarValue { + fn to_type<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + match *self { + ty::IntType(i) => tcx.mk_mach_int(i), + ty::UintType(i) => tcx.mk_mach_uint(i), + } + } +} + +// Floating point type keys + +impl UnifyKey for ty::FloatVid { + type Value = Option<FloatVarValue>; + fn index(&self) -> u32 { + self.index + } + fn from_index(i: u32) -> ty::FloatVid { + ty::FloatVid { index: i } + } + fn tag() -> &'static str { + "FloatVid" + } +} + +impl EqUnifyValue for FloatVarValue {} + +impl ToType for FloatVarValue { + fn to_type<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + tcx.mk_mach_float(self.0) + } +} + +// Generic consts. + +#[derive(Copy, Clone, Debug)] +pub struct ConstVariableOrigin { + pub kind: ConstVariableOriginKind, + pub span: Span, +} + +/// Reasons to create a const inference variable +#[derive(Copy, Clone, Debug)] +pub enum ConstVariableOriginKind { + MiscVariable, + ConstInference, + ConstParameterDefinition(Symbol), + SubstitutionPlaceholder, +} + +#[derive(Copy, Clone, Debug)] +pub enum ConstVariableValue<'tcx> { + Known { value: &'tcx ty::Const<'tcx> }, + Unknown { universe: ty::UniverseIndex }, +} + +impl<'tcx> ConstVariableValue<'tcx> { + /// If this value is known, returns the const it is known to be. + /// Otherwise, `None`. + pub fn known(&self) -> Option<&'tcx ty::Const<'tcx>> { + match *self { + ConstVariableValue::Unknown { .. } => None, + ConstVariableValue::Known { value } => Some(value), + } + } + + pub fn is_unknown(&self) -> bool { + match *self { + ConstVariableValue::Unknown { .. } => true, + ConstVariableValue::Known { .. } => false, + } + } +} + +#[derive(Copy, Clone, Debug)] +pub struct ConstVarValue<'tcx> { + pub origin: ConstVariableOrigin, + pub val: ConstVariableValue<'tcx>, +} + +impl<'tcx> UnifyKey for ty::ConstVid<'tcx> { + type Value = ConstVarValue<'tcx>; + fn index(&self) -> u32 { + self.index + } + fn from_index(i: u32) -> Self { + ty::ConstVid { index: i, phantom: PhantomData } + } + fn tag() -> &'static str { + "ConstVid" + } +} + +impl<'tcx> UnifyValue for ConstVarValue<'tcx> { + type Error = (&'tcx ty::Const<'tcx>, &'tcx ty::Const<'tcx>); + + fn unify_values(value1: &Self, value2: &Self) -> Result<Self, Self::Error> { + let val = match (value1.val, value2.val) { + (ConstVariableValue::Known { .. }, ConstVariableValue::Known { .. }) => { + bug!("equating two const variables, both of which have known values") + } + + // If one side is known, prefer that one. + (ConstVariableValue::Known { .. }, ConstVariableValue::Unknown { .. }) => { + Ok(value1.val) + } + (ConstVariableValue::Unknown { .. }, ConstVariableValue::Known { .. }) => { + Ok(value2.val) + } + + // If both sides are *unknown*, it hardly matters, does it? + ( + ConstVariableValue::Unknown { universe: universe1 }, + ConstVariableValue::Unknown { universe: universe2 }, + ) => { + // If we unify two unbound variables, ?T and ?U, then whatever + // value they wind up taking (which must be the same value) must + // be nameable by both universes. Therefore, the resulting + // universe is the minimum of the two universes, because that is + // the one which contains the fewest names in scope. + let universe = cmp::min(universe1, universe2); + Ok(ConstVariableValue::Unknown { universe }) + } + }?; + + Ok(ConstVarValue { + origin: ConstVariableOrigin { + kind: ConstVariableOriginKind::ConstInference, + span: DUMMY_SP, + }, + val, + }) + } +} + +impl<'tcx> EqUnifyValue for &'tcx ty::Const<'tcx> {} + +pub fn replace_if_possible<V, L>( + table: &mut UnificationTable<InPlace<ty::ConstVid<'tcx>, V, L>>, + c: &'tcx ty::Const<'tcx>, +) -> &'tcx ty::Const<'tcx> +where + V: snapshot_vec::VecLike<unify::Delegate<ty::ConstVid<'tcx>>>, + L: UndoLogs<snapshot_vec::UndoLog<unify::Delegate<ty::ConstVid<'tcx>>>>, +{ + if let ty::Const { val: ty::ConstKind::Infer(InferConst::Var(vid)), .. } = c { + match table.probe_value(*vid).val.known() { + Some(c) => c, + None => c, + } + } else { + c + } +} diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs new file mode 100644 index 00000000000..1b2dea8a378 --- /dev/null +++ b/compiler/rustc_middle/src/lib.rs @@ -0,0 +1,93 @@ +//! The "main crate" of the Rust compiler. This crate contains common +//! type definitions that are used by the other crates in the rustc +//! "family". Some prominent examples (note that each of these modules +//! has their own README with further details). +//! +//! - **HIR.** The "high-level (H) intermediate representation (IR)" is +//! defined in the `hir` module. +//! - **MIR.** The "mid-level (M) intermediate representation (IR)" is +//! defined in the `mir` module. This module contains only the +//! *definition* of the MIR; the passes that transform and operate +//! on MIR are found in `librustc_mir` crate. +//! - **Types.** The internal representation of types used in rustc is +//! defined in the `ty` module. This includes the **type context** +//! (or `tcx`), which is the central context during most of +//! compilation, containing the interners and other things. +//! +//! For more information about how rustc works, see the [rustc dev guide]. +//! +//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/ +//! +//! # Note +//! +//! This API is completely unstable and subject to change. + +#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")] +#![feature(backtrace)] +#![feature(bool_to_option)] +#![feature(box_patterns)] +#![feature(box_syntax)] +#![feature(cmp_min_max_by)] +#![feature(const_fn)] +#![feature(const_panic)] +#![feature(const_fn_transmute)] +#![feature(core_intrinsics)] +#![feature(discriminant_kind)] +#![feature(drain_filter)] +#![feature(never_type)] +#![feature(exhaustive_patterns)] +#![feature(extern_types)] +#![feature(nll)] +#![feature(option_expect_none)] +#![feature(or_patterns)] +#![feature(min_specialization)] +#![feature(trusted_len)] +#![feature(stmt_expr_attributes)] +#![feature(test)] +#![feature(in_band_lifetimes)] +#![feature(crate_visibility_modifier)] +#![feature(associated_type_bounds)] +#![feature(rustc_attrs)] +#![feature(hash_raw_entry)] +#![feature(int_error_matching)] +#![recursion_limit = "512"] + +#[macro_use] +extern crate bitflags; +#[macro_use] +extern crate rustc_macros; +#[macro_use] +extern crate rustc_data_structures; +#[macro_use] +extern crate tracing; +#[macro_use] +extern crate smallvec; + +#[cfg(test)] +mod tests; + +#[macro_use] +mod macros; + +#[macro_use] +pub mod query; + +#[macro_use] +pub mod arena; +pub mod dep_graph; +pub mod hir; +pub mod ich; +pub mod infer; +pub mod lint; +pub mod middle; +pub mod mir; +pub mod traits; +pub mod ty; + +pub mod util { + pub mod bug; + pub mod common; +} + +// Allows macros to refer to this crate as `::rustc_middle` +extern crate self as rustc_middle; diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs new file mode 100644 index 00000000000..25e5379881e --- /dev/null +++ b/compiler/rustc_middle/src/lint.rs @@ -0,0 +1,351 @@ +use std::cmp; + +use crate::ich::StableHashingContext; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_errors::{DiagnosticBuilder, DiagnosticId}; +use rustc_hir::HirId; +use rustc_session::lint::{builtin, Level, Lint, LintId}; +use rustc_session::{DiagnosticMessageId, Session}; +use rustc_span::hygiene::MacroKind; +use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan}; +use rustc_span::{Span, Symbol}; + +/// How a lint level was set. +#[derive(Clone, Copy, PartialEq, Eq, HashStable)] +pub enum LintSource { + /// Lint is at the default level as declared + /// in rustc or a plugin. + Default, + + /// Lint level was set by an attribute. + Node(Symbol, Span, Option<Symbol> /* RFC 2383 reason */), + + /// Lint level was set by a command-line flag. + CommandLine(Symbol), +} + +pub type LevelSource = (Level, LintSource); + +pub struct LintLevelSets { + pub list: Vec<LintSet>, + pub lint_cap: Level, +} + +pub enum LintSet { + CommandLine { + // -A,-W,-D flags, a `Symbol` for the flag itself and `Level` for which + // flag. + specs: FxHashMap<LintId, LevelSource>, + }, + + Node { + specs: FxHashMap<LintId, LevelSource>, + parent: u32, + }, +} + +impl LintLevelSets { + pub fn new() -> Self { + LintLevelSets { list: Vec::new(), lint_cap: Level::Forbid } + } + + pub fn get_lint_level( + &self, + lint: &'static Lint, + idx: u32, + aux: Option<&FxHashMap<LintId, LevelSource>>, + sess: &Session, + ) -> LevelSource { + let (level, mut src) = self.get_lint_id_level(LintId::of(lint), idx, aux); + + // If `level` is none then we actually assume the default level for this + // lint. + let mut level = level.unwrap_or_else(|| lint.default_level(sess.edition())); + + // If we're about to issue a warning, check at the last minute for any + // directives against the warnings "lint". If, for example, there's an + // `allow(warnings)` in scope then we want to respect that instead. + if level == Level::Warn { + let (warnings_level, warnings_src) = + self.get_lint_id_level(LintId::of(builtin::WARNINGS), idx, aux); + if let Some(configured_warning_level) = warnings_level { + if configured_warning_level != Level::Warn { + level = configured_warning_level; + src = warnings_src; + } + } + } + + // Ensure that we never exceed the `--cap-lints` argument. + level = cmp::min(level, self.lint_cap); + + if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) { + // Ensure that we never exceed driver level. + level = cmp::min(*driver_level, level); + } + + (level, src) + } + + pub fn get_lint_id_level( + &self, + id: LintId, + mut idx: u32, + aux: Option<&FxHashMap<LintId, LevelSource>>, + ) -> (Option<Level>, LintSource) { + if let Some(specs) = aux { + if let Some(&(level, src)) = specs.get(&id) { + return (Some(level), src); + } + } + loop { + match self.list[idx as usize] { + LintSet::CommandLine { ref specs } => { + if let Some(&(level, src)) = specs.get(&id) { + return (Some(level), src); + } + return (None, LintSource::Default); + } + LintSet::Node { ref specs, parent } => { + if let Some(&(level, src)) = specs.get(&id) { + return (Some(level), src); + } + idx = parent; + } + } + } + } +} + +pub struct LintLevelMap { + pub sets: LintLevelSets, + pub id_to_set: FxHashMap<HirId, u32>, +} + +impl LintLevelMap { + /// If the `id` was previously registered with `register_id` when building + /// this `LintLevelMap` this returns the corresponding lint level and source + /// of the lint level for the lint provided. + /// + /// If the `id` was not previously registered, returns `None`. If `None` is + /// returned then the parent of `id` should be acquired and this function + /// should be called again. + pub fn level_and_source( + &self, + lint: &'static Lint, + id: HirId, + session: &Session, + ) -> Option<LevelSource> { + self.id_to_set.get(&id).map(|idx| self.sets.get_lint_level(lint, *idx, None, session)) + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap { + #[inline] + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let LintLevelMap { ref sets, ref id_to_set } = *self; + + id_to_set.hash_stable(hcx, hasher); + + let LintLevelSets { ref list, lint_cap } = *sets; + + lint_cap.hash_stable(hcx, hasher); + + hcx.while_hashing_spans(true, |hcx| { + list.len().hash_stable(hcx, hasher); + + // We are working under the assumption here that the list of + // lint-sets is built in a deterministic order. + for lint_set in list { + ::std::mem::discriminant(lint_set).hash_stable(hcx, hasher); + + match *lint_set { + LintSet::CommandLine { ref specs } => { + specs.hash_stable(hcx, hasher); + } + LintSet::Node { ref specs, parent } => { + specs.hash_stable(hcx, hasher); + parent.hash_stable(hcx, hasher); + } + } + } + }) + } +} + +pub struct LintDiagnosticBuilder<'a>(DiagnosticBuilder<'a>); + +impl<'a> LintDiagnosticBuilder<'a> { + /// Return the inner DiagnosticBuilder, first setting the primary message to `msg`. + pub fn build(mut self, msg: &str) -> DiagnosticBuilder<'a> { + self.0.set_primary_message(msg); + self.0 + } + + /// Create a LintDiagnosticBuilder from some existing DiagnosticBuilder. + pub fn new(err: DiagnosticBuilder<'a>) -> LintDiagnosticBuilder<'a> { + LintDiagnosticBuilder(err) + } +} + +pub fn struct_lint_level<'s, 'd>( + sess: &'s Session, + lint: &'static Lint, + level: Level, + src: LintSource, + span: Option<MultiSpan>, + decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>) + 'd, +) { + // Avoid codegen bloat from monomorphization by immediately doing dyn dispatch of `decorate` to + // the "real" work. + fn struct_lint_level_impl( + sess: &'s Session, + lint: &'static Lint, + level: Level, + src: LintSource, + span: Option<MultiSpan>, + decorate: Box<dyn for<'b> FnOnce(LintDiagnosticBuilder<'b>) + 'd>, + ) { + let mut err = match (level, span) { + (Level::Allow, _) => { + return; + } + (Level::Warn, Some(span)) => sess.struct_span_warn(span, ""), + (Level::Warn, None) => sess.struct_warn(""), + (Level::Deny | Level::Forbid, Some(span)) => sess.struct_span_err(span, ""), + (Level::Deny | Level::Forbid, None) => sess.struct_err(""), + }; + + // Check for future incompatibility lints and issue a stronger warning. + let lint_id = LintId::of(lint); + let future_incompatible = lint.future_incompatible; + + // If this code originates in a foreign macro, aka something that this crate + // did not itself author, then it's likely that there's nothing this crate + // can do about it. We probably want to skip the lint entirely. + if err.span.primary_spans().iter().any(|s| in_external_macro(sess, *s)) { + // Any suggestions made here are likely to be incorrect, so anything we + // emit shouldn't be automatically fixed by rustfix. + err.allow_suggestions(false); + + // If this is a future incompatible lint it'll become a hard error, so + // we have to emit *something*. Also, if this lint occurs in the + // expansion of a macro from an external crate, allow individual lints + // to opt-out from being reported. + if future_incompatible.is_none() && !lint.report_in_external_macro { + err.cancel(); + // Don't continue further, since we don't want to have + // `diag_span_note_once` called for a diagnostic that isn't emitted. + return; + } + } + + let name = lint.name_lower(); + match src { + LintSource::Default => { + sess.diag_note_once( + &mut err, + DiagnosticMessageId::from(lint), + &format!("`#[{}({})]` on by default", level.as_str(), name), + ); + } + LintSource::CommandLine(lint_flag_val) => { + let flag = match level { + Level::Warn => "-W", + Level::Deny => "-D", + Level::Forbid => "-F", + Level::Allow => panic!(), + }; + let hyphen_case_lint_name = name.replace("_", "-"); + if lint_flag_val.as_str() == name { + sess.diag_note_once( + &mut err, + DiagnosticMessageId::from(lint), + &format!( + "requested on the command line with `{} {}`", + flag, hyphen_case_lint_name + ), + ); + } else { + let hyphen_case_flag_val = lint_flag_val.as_str().replace("_", "-"); + sess.diag_note_once( + &mut err, + DiagnosticMessageId::from(lint), + &format!( + "`{} {}` implied by `{} {}`", + flag, hyphen_case_lint_name, flag, hyphen_case_flag_val + ), + ); + } + } + LintSource::Node(lint_attr_name, src, reason) => { + if let Some(rationale) = reason { + err.note(&rationale.as_str()); + } + sess.diag_span_note_once( + &mut err, + DiagnosticMessageId::from(lint), + src, + "the lint level is defined here", + ); + if lint_attr_name.as_str() != name { + let level_str = level.as_str(); + sess.diag_note_once( + &mut err, + DiagnosticMessageId::from(lint), + &format!( + "`#[{}({})]` implied by `#[{}({})]`", + level_str, name, level_str, lint_attr_name + ), + ); + } + } + } + + err.code(DiagnosticId::Lint(name)); + + if let Some(future_incompatible) = future_incompatible { + const STANDARD_MESSAGE: &str = "this was previously accepted by the compiler but is being phased out; \ + it will become a hard error"; + + let explanation = if lint_id == LintId::of(builtin::UNSTABLE_NAME_COLLISIONS) { + "once this method is added to the standard library, \ + the ambiguity may cause an error or change in behavior!" + .to_owned() + } else if lint_id == LintId::of(builtin::MUTABLE_BORROW_RESERVATION_CONFLICT) { + "this borrowing pattern was not meant to be accepted, \ + and may become a hard error in the future" + .to_owned() + } else if let Some(edition) = future_incompatible.edition { + format!("{} in the {} edition!", STANDARD_MESSAGE, edition) + } else { + format!("{} in a future release!", STANDARD_MESSAGE) + }; + let citation = format!("for more information, see {}", future_incompatible.reference); + err.warn(&explanation); + err.note(&citation); + } + + // Finally, run `decorate`. This function is also responsible for emitting the diagnostic. + decorate(LintDiagnosticBuilder::new(err)); + } + struct_lint_level_impl(sess, lint, level, src, span, Box::new(decorate)) +} + +/// Returns whether `span` originates in a foreign crate's external macro. +/// +/// This is used to test whether a lint should not even begin to figure out whether it should +/// be reported on the current node. +pub fn in_external_macro(sess: &Session, span: Span) -> bool { + let expn_data = span.ctxt().outer_expn_data(); + match expn_data.kind { + ExpnKind::Root | ExpnKind::Desugaring(DesugaringKind::ForLoop(_)) => false, + ExpnKind::AstPass(_) | ExpnKind::Desugaring(_) => true, // well, it's "external" + ExpnKind::Macro(MacroKind::Bang, _) => { + // Dummy span for the `def_site` means it's an external macro. + expn_data.def_site.is_dummy() || sess.source_map().is_imported(expn_data.def_site) + } + ExpnKind::Macro { .. } => true, // definitely a plugin + } +} diff --git a/compiler/rustc_middle/src/macros.rs b/compiler/rustc_middle/src/macros.rs new file mode 100644 index 00000000000..a5482b7bdcf --- /dev/null +++ b/compiler/rustc_middle/src/macros.rs @@ -0,0 +1,220 @@ +#[macro_export] +macro_rules! bug { + () => ( $crate::bug!("impossible case reached") ); + ($msg:expr) => ({ $crate::util::bug::bug_fmt(::std::format_args!($msg)) }); + ($msg:expr,) => ({ $crate::bug!($msg) }); + ($fmt:expr, $($arg:tt)+) => ({ + $crate::util::bug::bug_fmt(::std::format_args!($fmt, $($arg)+)) + }); +} + +#[macro_export] +macro_rules! span_bug { + ($span:expr, $msg:expr) => ({ $crate::util::bug::span_bug_fmt($span, ::std::format_args!($msg)) }); + ($span:expr, $msg:expr,) => ({ $crate::span_bug!($span, $msg) }); + ($span:expr, $fmt:expr, $($arg:tt)+) => ({ + $crate::util::bug::span_bug_fmt($span, ::std::format_args!($fmt, $($arg)+)) + }); +} + +/////////////////////////////////////////////////////////////////////////// +// Lift and TypeFoldable macros +// +// When possible, use one of these (relatively) convenient macros to write +// the impls for you. + +#[macro_export] +macro_rules! CloneLiftImpls { + (for <$tcx:lifetime> { $($ty:ty,)+ }) => { + $( + impl<$tcx> $crate::ty::Lift<$tcx> for $ty { + type Lifted = Self; + fn lift_to_tcx(&self, _: $crate::ty::TyCtxt<$tcx>) -> Option<Self> { + Some(Clone::clone(self)) + } + } + )+ + }; + + ($($ty:ty,)+) => { + CloneLiftImpls! { + for <'tcx> { + $($ty,)+ + } + } + }; +} + +/// Used for types that are `Copy` and which **do not care arena +/// allocated data** (i.e., don't need to be folded). +#[macro_export] +macro_rules! CloneTypeFoldableImpls { + (for <$tcx:lifetime> { $($ty:ty,)+ }) => { + $( + impl<$tcx> $crate::ty::fold::TypeFoldable<$tcx> for $ty { + fn super_fold_with<F: $crate::ty::fold::TypeFolder<$tcx>>( + &self, + _: &mut F + ) -> $ty { + Clone::clone(self) + } + + fn super_visit_with<F: $crate::ty::fold::TypeVisitor<$tcx>>( + &self, + _: &mut F) + -> bool + { + false + } + } + )+ + }; + + ($($ty:ty,)+) => { + CloneTypeFoldableImpls! { + for <'tcx> { + $($ty,)+ + } + } + }; +} + +#[macro_export] +macro_rules! CloneTypeFoldableAndLiftImpls { + ($($t:tt)*) => { + CloneTypeFoldableImpls! { $($t)* } + CloneLiftImpls! { $($t)* } + } +} + +#[macro_export] +macro_rules! EnumTypeFoldableImpl { + (impl<$($p:tt),*> TypeFoldable<$tcx:tt> for $s:path { + $($variants:tt)* + } $(where $($wc:tt)*)*) => { + impl<$($p),*> $crate::ty::fold::TypeFoldable<$tcx> for $s + $(where $($wc)*)* + { + fn super_fold_with<V: $crate::ty::fold::TypeFolder<$tcx>>( + &self, + folder: &mut V, + ) -> Self { + EnumTypeFoldableImpl!(@FoldVariants(self, folder) input($($variants)*) output()) + } + + fn super_visit_with<V: $crate::ty::fold::TypeVisitor<$tcx>>( + &self, + visitor: &mut V, + ) -> bool { + EnumTypeFoldableImpl!(@VisitVariants(self, visitor) input($($variants)*) output()) + } + } + }; + + (@FoldVariants($this:expr, $folder:expr) input() output($($output:tt)*)) => { + match $this { + $($output)* + } + }; + + (@FoldVariants($this:expr, $folder:expr) + input( ($variant:path) ( $($variant_arg:ident),* ) , $($input:tt)*) + output( $($output:tt)*) ) => { + EnumTypeFoldableImpl!( + @FoldVariants($this, $folder) + input($($input)*) + output( + $variant ( $($variant_arg),* ) => { + $variant ( + $($crate::ty::fold::TypeFoldable::fold_with($variant_arg, $folder)),* + ) + } + $($output)* + ) + ) + }; + + (@FoldVariants($this:expr, $folder:expr) + input( ($variant:path) { $($variant_arg:ident),* $(,)? } , $($input:tt)*) + output( $($output:tt)*) ) => { + EnumTypeFoldableImpl!( + @FoldVariants($this, $folder) + input($($input)*) + output( + $variant { $($variant_arg),* } => { + $variant { + $($variant_arg: $crate::ty::fold::TypeFoldable::fold_with( + $variant_arg, $folder + )),* } + } + $($output)* + ) + ) + }; + + (@FoldVariants($this:expr, $folder:expr) + input( ($variant:path), $($input:tt)*) + output( $($output:tt)*) ) => { + EnumTypeFoldableImpl!( + @FoldVariants($this, $folder) + input($($input)*) + output( + $variant => { $variant } + $($output)* + ) + ) + }; + + (@VisitVariants($this:expr, $visitor:expr) input() output($($output:tt)*)) => { + match $this { + $($output)* + } + }; + + (@VisitVariants($this:expr, $visitor:expr) + input( ($variant:path) ( $($variant_arg:ident),* ) , $($input:tt)*) + output( $($output:tt)*) ) => { + EnumTypeFoldableImpl!( + @VisitVariants($this, $visitor) + input($($input)*) + output( + $variant ( $($variant_arg),* ) => { + false $(|| $crate::ty::fold::TypeFoldable::visit_with( + $variant_arg, $visitor + ))* + } + $($output)* + ) + ) + }; + + (@VisitVariants($this:expr, $visitor:expr) + input( ($variant:path) { $($variant_arg:ident),* $(,)? } , $($input:tt)*) + output( $($output:tt)*) ) => { + EnumTypeFoldableImpl!( + @VisitVariants($this, $visitor) + input($($input)*) + output( + $variant { $($variant_arg),* } => { + false $(|| $crate::ty::fold::TypeFoldable::visit_with( + $variant_arg, $visitor + ))* + } + $($output)* + ) + ) + }; + + (@VisitVariants($this:expr, $visitor:expr) + input( ($variant:path), $($input:tt)*) + output( $($output:tt)*) ) => { + EnumTypeFoldableImpl!( + @VisitVariants($this, $visitor) + input($($input)*) + output( + $variant => { false } + $($output)* + ) + ) + }; +} diff --git a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs new file mode 100644 index 00000000000..62a6198b9b4 --- /dev/null +++ b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs @@ -0,0 +1,124 @@ +use crate::mir::mono::Linkage; +use rustc_attr::{InlineAttr, OptimizeAttr}; +use rustc_session::config::SanitizerSet; +use rustc_span::symbol::Symbol; + +#[derive(Clone, TyEncodable, TyDecodable, HashStable)] +pub struct CodegenFnAttrs { + pub flags: CodegenFnAttrFlags, + /// Parsed representation of the `#[inline]` attribute + pub inline: InlineAttr, + /// Parsed representation of the `#[optimize]` attribute + pub optimize: OptimizeAttr, + /// The `#[export_name = "..."]` attribute, indicating a custom symbol a + /// function should be exported under + pub export_name: Option<Symbol>, + /// The `#[link_name = "..."]` attribute, indicating a custom symbol an + /// imported function should be imported as. Note that `export_name` + /// probably isn't set when this is set, this is for foreign items while + /// `#[export_name]` is for Rust-defined functions. + pub link_name: Option<Symbol>, + /// The `#[link_ordinal = "..."]` attribute, indicating an ordinal an + /// imported function has in the dynamic library. Note that this must not + /// be set when `link_name` is set. This is for foreign items with the + /// "raw-dylib" kind. + pub link_ordinal: Option<usize>, + /// The `#[target_feature(enable = "...")]` attribute and the enabled + /// features (only enabled features are supported right now). + pub target_features: Vec<Symbol>, + /// The `#[linkage = "..."]` attribute and the value we found. + pub linkage: Option<Linkage>, + /// The `#[link_section = "..."]` attribute, or what executable section this + /// should be placed in. + pub link_section: Option<Symbol>, + /// The `#[no_sanitize(...)]` attribute. Indicates sanitizers for which + /// instrumentation should be disabled inside the annotated function. + pub no_sanitize: SanitizerSet, +} + +bitflags! { + #[derive(TyEncodable, TyDecodable, HashStable)] + pub struct CodegenFnAttrFlags: u32 { + /// `#[cold]`: a hint to LLVM that this function, when called, is never on + /// the hot path. + const COLD = 1 << 0; + /// `#[rustc_allocator]`: a hint to LLVM that the pointer returned from this + /// function is never null. + const ALLOCATOR = 1 << 1; + /// `#[unwind]`: an indicator that this function may unwind despite what + /// its ABI signature may otherwise imply. + const UNWIND = 1 << 2; + /// `#[rust_allocator_nounwind]`, an indicator that an imported FFI + /// function will never unwind. Probably obsolete by recent changes with + /// #[unwind], but hasn't been removed/migrated yet + const RUSTC_ALLOCATOR_NOUNWIND = 1 << 3; + /// `#[naked]`: an indicator to LLVM that no function prologue/epilogue + /// should be generated. + const NAKED = 1 << 4; + /// `#[no_mangle]`: an indicator that the function's name should be the same + /// as its symbol. + const NO_MANGLE = 1 << 5; + /// `#[rustc_std_internal_symbol]`: an indicator that this symbol is a + /// "weird symbol" for the standard library in that it has slightly + /// different linkage, visibility, and reachability rules. + const RUSTC_STD_INTERNAL_SYMBOL = 1 << 6; + /// `#[thread_local]`: indicates a static is actually a thread local + /// piece of memory + const THREAD_LOCAL = 1 << 8; + /// `#[used]`: indicates that LLVM can't eliminate this function (but the + /// linker can!). + const USED = 1 << 9; + /// `#[ffi_returns_twice]`, indicates that an extern function can return + /// multiple times + const FFI_RETURNS_TWICE = 1 << 10; + /// `#[track_caller]`: allow access to the caller location + const TRACK_CALLER = 1 << 11; + /// #[ffi_pure]: applies clang's `pure` attribute to a foreign function + /// declaration. + const FFI_PURE = 1 << 12; + /// #[ffi_const]: applies clang's `const` attribute to a foreign function + /// declaration. + const FFI_CONST = 1 << 13; + } +} + +impl CodegenFnAttrs { + pub fn new() -> CodegenFnAttrs { + CodegenFnAttrs { + flags: CodegenFnAttrFlags::empty(), + inline: InlineAttr::None, + optimize: OptimizeAttr::None, + export_name: None, + link_name: None, + link_ordinal: None, + target_features: vec![], + linkage: None, + link_section: None, + no_sanitize: SanitizerSet::empty(), + } + } + + /// Returns `true` if `#[inline]` or `#[inline(always)]` is present. + pub fn requests_inline(&self) -> bool { + match self.inline { + InlineAttr::Hint | InlineAttr::Always => true, + InlineAttr::None | InlineAttr::Never => false, + } + } + + /// Returns `true` if it looks like this symbol needs to be exported, for example: + /// + /// * `#[no_mangle]` is present + /// * `#[export_name(...)]` is present + /// * `#[linkage]` is present + pub fn contains_extern_indicator(&self) -> bool { + self.flags.contains(CodegenFnAttrFlags::NO_MANGLE) + || self.export_name.is_some() + || match self.linkage { + // These are private, so make sure we don't try to consider + // them external. + None | Some(Linkage::Internal | Linkage::Private) => false, + Some(_) => true, + } + } +} diff --git a/compiler/rustc_middle/src/middle/cstore.rs b/compiler/rustc_middle/src/middle/cstore.rs new file mode 100644 index 00000000000..1af1d581817 --- /dev/null +++ b/compiler/rustc_middle/src/middle/cstore.rs @@ -0,0 +1,251 @@ +//! the rustc crate store interface. This also includes types that +//! are *mostly* used as a part of that interface, but these should +//! probably get a better home if someone can find one. + +use crate::ty::TyCtxt; + +use rustc_ast as ast; +use rustc_ast::expand::allocator::AllocatorKind; +use rustc_data_structures::svh::Svh; +use rustc_data_structures::sync::{self, MetadataRef}; +use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE}; +use rustc_hir::definitions::{DefKey, DefPath, DefPathHash}; +use rustc_macros::HashStable; +use rustc_session::search_paths::PathKind; +use rustc_session::utils::NativeLibKind; +use rustc_session::CrateDisambiguator; +use rustc_span::symbol::Symbol; +use rustc_span::Span; +use rustc_target::spec::Target; + +use std::any::Any; +use std::path::{Path, PathBuf}; + +// lonely orphan structs and enums looking for a better home + +/// Where a crate came from on the local filesystem. One of these three options +/// must be non-None. +#[derive(PartialEq, Clone, Debug, HashStable, Encodable, Decodable)] +pub struct CrateSource { + pub dylib: Option<(PathBuf, PathKind)>, + pub rlib: Option<(PathBuf, PathKind)>, + pub rmeta: Option<(PathBuf, PathKind)>, +} + +impl CrateSource { + pub fn paths(&self) -> impl Iterator<Item = &PathBuf> { + self.dylib.iter().chain(self.rlib.iter()).chain(self.rmeta.iter()).map(|p| &p.0) + } +} + +#[derive(Encodable, Decodable, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug)] +#[derive(HashStable)] +pub enum CrateDepKind { + /// A dependency that is only used for its macros. + MacrosOnly, + /// A dependency that is always injected into the dependency list and so + /// doesn't need to be linked to an rlib, e.g., the injected allocator. + Implicit, + /// A dependency that is required by an rlib version of this crate. + /// Ordinary `extern crate`s result in `Explicit` dependencies. + Explicit, +} + +impl CrateDepKind { + pub fn macros_only(self) -> bool { + match self { + CrateDepKind::MacrosOnly => true, + CrateDepKind::Implicit | CrateDepKind::Explicit => false, + } + } +} + +#[derive(PartialEq, Clone, Debug, Encodable, Decodable)] +pub enum LibSource { + Some(PathBuf), + MetadataOnly, + None, +} + +impl LibSource { + pub fn is_some(&self) -> bool { + if let LibSource::Some(_) = *self { true } else { false } + } + + pub fn option(&self) -> Option<PathBuf> { + match *self { + LibSource::Some(ref p) => Some(p.clone()), + LibSource::MetadataOnly | LibSource::None => None, + } + } +} + +#[derive(Copy, Debug, PartialEq, Clone, Encodable, Decodable, HashStable)] +pub enum LinkagePreference { + RequireDynamic, + RequireStatic, +} + +#[derive(Clone, Debug, Encodable, Decodable, HashStable)] +pub struct NativeLib { + pub kind: NativeLibKind, + pub name: Option<Symbol>, + pub cfg: Option<ast::MetaItem>, + pub foreign_module: Option<DefId>, + pub wasm_import_module: Option<Symbol>, +} + +#[derive(Clone, TyEncodable, TyDecodable, HashStable)] +pub struct ForeignModule { + pub foreign_items: Vec<DefId>, + pub def_id: DefId, +} + +#[derive(Copy, Clone, Debug, HashStable)] +pub struct ExternCrate { + pub src: ExternCrateSource, + + /// span of the extern crate that caused this to be loaded + pub span: Span, + + /// Number of links to reach the extern; + /// used to select the extern with the shortest path + pub path_len: usize, + + /// Crate that depends on this crate + pub dependency_of: CrateNum, +} + +impl ExternCrate { + /// If true, then this crate is the crate named by the extern + /// crate referenced above. If false, then this crate is a dep + /// of the crate. + pub fn is_direct(&self) -> bool { + self.dependency_of == LOCAL_CRATE + } + + pub fn rank(&self) -> impl PartialOrd { + // Prefer: + // - direct extern crate to indirect + // - shorter paths to longer + (self.is_direct(), !self.path_len) + } +} + +#[derive(Copy, Clone, Debug, HashStable)] +pub enum ExternCrateSource { + /// Crate is loaded by `extern crate`. + Extern( + /// def_id of the item in the current crate that caused + /// this crate to be loaded; note that there could be multiple + /// such ids + DefId, + ), + /// Crate is implicitly loaded by a path resolving through extern prelude. + Path, +} + +#[derive(Encodable, Decodable)] +pub struct EncodedMetadata { + pub raw_data: Vec<u8>, +} + +impl EncodedMetadata { + pub fn new() -> EncodedMetadata { + EncodedMetadata { raw_data: Vec::new() } + } +} + +/// The backend's way to give the crate store access to the metadata in a library. +/// Note that it returns the raw metadata bytes stored in the library file, whether +/// it is compressed, uncompressed, some weird mix, etc. +/// rmeta files are backend independent and not handled here. +/// +/// At the time of this writing, there is only one backend and one way to store +/// metadata in library -- this trait just serves to decouple rustc_metadata from +/// the archive reader, which depends on LLVM. +pub trait MetadataLoader { + fn get_rlib_metadata(&self, target: &Target, filename: &Path) -> Result<MetadataRef, String>; + fn get_dylib_metadata(&self, target: &Target, filename: &Path) -> Result<MetadataRef, String>; +} + +pub type MetadataLoaderDyn = dyn MetadataLoader + Sync; + +/// A store of Rust crates, through which their metadata can be accessed. +/// +/// Note that this trait should probably not be expanding today. All new +/// functionality should be driven through queries instead! +/// +/// If you find a method on this trait named `{name}_untracked` it signifies +/// that it's *not* tracked for dependency information throughout compilation +/// (it'd break incremental compilation) and should only be called pre-HIR (e.g. +/// during resolve) +pub trait CrateStore { + fn as_any(&self) -> &dyn Any; + + // resolve + fn def_key(&self, def: DefId) -> DefKey; + fn def_path(&self, def: DefId) -> DefPath; + fn def_path_hash(&self, def: DefId) -> DefPathHash; + fn all_def_path_hashes_and_def_ids(&self, cnum: CrateNum) -> Vec<(DefPathHash, DefId)>; + fn num_def_ids(&self, cnum: CrateNum) -> usize; + + // "queries" used in resolve that aren't tracked for incremental compilation + fn crate_name_untracked(&self, cnum: CrateNum) -> Symbol; + fn crate_is_private_dep_untracked(&self, cnum: CrateNum) -> bool; + fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> CrateDisambiguator; + fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh; + + // This is basically a 1-based range of ints, which is a little + // silly - I may fix that. + fn crates_untracked(&self) -> Vec<CrateNum>; + + // utility functions + fn encode_metadata(&self, tcx: TyCtxt<'_>) -> EncodedMetadata; + fn metadata_encoding_version(&self) -> &[u8]; + fn allocator_kind(&self) -> Option<AllocatorKind>; +} + +pub type CrateStoreDyn = dyn CrateStore + sync::Sync; + +// This method is used when generating the command line to pass through to +// system linker. The linker expects undefined symbols on the left of the +// command line to be defined in libraries on the right, not the other way +// around. For more info, see some comments in the add_used_library function +// below. +// +// In order to get this left-to-right dependency ordering, we perform a +// topological sort of all crates putting the leaves at the right-most +// positions. +pub fn used_crates(tcx: TyCtxt<'_>, prefer: LinkagePreference) -> Vec<(CrateNum, LibSource)> { + let mut libs = tcx + .crates() + .iter() + .cloned() + .filter_map(|cnum| { + if tcx.dep_kind(cnum).macros_only() { + return None; + } + let source = tcx.used_crate_source(cnum); + let path = match prefer { + LinkagePreference::RequireDynamic => source.dylib.clone().map(|p| p.0), + LinkagePreference::RequireStatic => source.rlib.clone().map(|p| p.0), + }; + let path = match path { + Some(p) => LibSource::Some(p), + None => { + if source.rmeta.is_some() { + LibSource::MetadataOnly + } else { + LibSource::None + } + } + }; + Some((cnum, path)) + }) + .collect::<Vec<_>>(); + let mut ordering = tcx.postorder_cnums(LOCAL_CRATE).to_owned(); + ordering.reverse(); + libs.sort_by_cached_key(|&(a, _)| ordering.iter().position(|x| *x == a)); + libs +} diff --git a/compiler/rustc_middle/src/middle/dependency_format.rs b/compiler/rustc_middle/src/middle/dependency_format.rs new file mode 100644 index 00000000000..e079843bfbc --- /dev/null +++ b/compiler/rustc_middle/src/middle/dependency_format.rs @@ -0,0 +1,28 @@ +//! Type definitions for learning about the dependency formats of all upstream +//! crates (rlibs/dylibs/oh my). +//! +//! For all the gory details, see the provider of the `dependency_formats` +//! query. + +use rustc_session::config::CrateType; + +/// A list of dependencies for a certain crate type. +/// +/// The length of this vector is the same as the number of external crates used. +/// The value is None if the crate does not need to be linked (it was found +/// statically in another dylib), or Some(kind) if it needs to be linked as +/// `kind` (either static or dynamic). +pub type DependencyList = Vec<Linkage>; + +/// A mapping of all required dependencies for a particular flavor of output. +/// +/// This is local to the tcx, and is generally relevant to one session. +pub type Dependencies = Vec<(CrateType, DependencyList)>; + +#[derive(Copy, Clone, PartialEq, Debug, HashStable, Encodable, Decodable)] +pub enum Linkage { + NotLinked, + IncludedFromDylib, + Static, + Dynamic, +} diff --git a/compiler/rustc_middle/src/middle/exported_symbols.rs b/compiler/rustc_middle/src/middle/exported_symbols.rs new file mode 100644 index 00000000000..276e45ce99b --- /dev/null +++ b/compiler/rustc_middle/src/middle/exported_symbols.rs @@ -0,0 +1,55 @@ +use crate::ty::subst::SubstsRef; +use crate::ty::{self, Ty, TyCtxt}; +use rustc_hir::def_id::{DefId, LOCAL_CRATE}; +use rustc_macros::HashStable; + +/// The SymbolExportLevel of a symbols specifies from which kinds of crates +/// the symbol will be exported. `C` symbols will be exported from any +/// kind of crate, including cdylibs which export very few things. +/// `Rust` will only be exported if the crate produced is a Rust +/// dylib. +#[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)] +pub enum SymbolExportLevel { + C, + Rust, +} + +impl SymbolExportLevel { + pub fn is_below_threshold(self, threshold: SymbolExportLevel) -> bool { + threshold == SymbolExportLevel::Rust // export everything from Rust dylibs + || self == SymbolExportLevel::C + } +} + +#[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)] +pub enum ExportedSymbol<'tcx> { + NonGeneric(DefId), + Generic(DefId, SubstsRef<'tcx>), + DropGlue(Ty<'tcx>), + NoDefId(ty::SymbolName<'tcx>), +} + +impl<'tcx> ExportedSymbol<'tcx> { + /// This is the symbol name of an instance if it is instantiated in the + /// local crate. + pub fn symbol_name_for_local_instance(&self, tcx: TyCtxt<'tcx>) -> ty::SymbolName<'tcx> { + match *self { + ExportedSymbol::NonGeneric(def_id) => tcx.symbol_name(ty::Instance::mono(tcx, def_id)), + ExportedSymbol::Generic(def_id, substs) => { + tcx.symbol_name(ty::Instance::new(def_id, substs)) + } + ExportedSymbol::DropGlue(ty) => { + tcx.symbol_name(ty::Instance::resolve_drop_in_place(tcx, ty)) + } + ExportedSymbol::NoDefId(symbol_name) => symbol_name, + } + } +} + +pub fn metadata_symbol_name(tcx: TyCtxt<'_>) -> String { + format!( + "rust_metadata_{}_{}", + tcx.original_crate_name(LOCAL_CRATE), + tcx.crate_disambiguator(LOCAL_CRATE).to_fingerprint().to_hex() + ) +} diff --git a/compiler/rustc_middle/src/middle/lang_items.rs b/compiler/rustc_middle/src/middle/lang_items.rs new file mode 100644 index 00000000000..7194a035e89 --- /dev/null +++ b/compiler/rustc_middle/src/middle/lang_items.rs @@ -0,0 +1,61 @@ +//! Detecting language items. +//! +//! Language items are items that represent concepts intrinsic to the language +//! itself. Examples are: +//! +//! * Traits that specify "kinds"; e.g., `Sync`, `Send`. +//! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`. +//! * Functions called by the compiler itself. + +use crate::ty::{self, TyCtxt}; + +use rustc_hir::def_id::DefId; +use rustc_hir::LangItem; +use rustc_span::Span; +use rustc_target::spec::PanicStrategy; + +impl<'tcx> TyCtxt<'tcx> { + /// Returns the `DefId` for a given `LangItem`. + /// If not found, fatally aborts compilation. + pub fn require_lang_item(&self, lang_item: LangItem, span: Option<Span>) -> DefId { + self.lang_items().require(lang_item).unwrap_or_else(|msg| { + if let Some(span) = span { + self.sess.span_fatal(span, &msg) + } else { + self.sess.fatal(&msg) + } + }) + } + + pub fn fn_trait_kind_from_lang_item(&self, id: DefId) -> Option<ty::ClosureKind> { + let items = self.lang_items(); + match Some(id) { + x if x == items.fn_trait() => Some(ty::ClosureKind::Fn), + x if x == items.fn_mut_trait() => Some(ty::ClosureKind::FnMut), + x if x == items.fn_once_trait() => Some(ty::ClosureKind::FnOnce), + _ => None, + } + } + + pub fn is_weak_lang_item(&self, item_def_id: DefId) -> bool { + self.lang_items().is_weak_lang_item(item_def_id) + } +} + +/// Returns `true` if the specified `lang_item` must be present for this +/// compilation. +/// +/// Not all lang items are always required for each compilation, particularly in +/// the case of panic=abort. In these situations some lang items are injected by +/// crates and don't actually need to be defined in libstd. +pub fn required(tcx: TyCtxt<'_>, lang_item: LangItem) -> bool { + // If we're not compiling with unwinding, we won't actually need these + // symbols. Other panic runtimes ensure that the relevant symbols are + // available to link things together, but they're never exercised. + match tcx.sess.panic_strategy() { + PanicStrategy::Abort => { + lang_item != LangItem::EhPersonality && lang_item != LangItem::EhCatchTypeinfo + } + PanicStrategy::Unwind => true, + } +} diff --git a/compiler/rustc_middle/src/middle/limits.rs b/compiler/rustc_middle/src/middle/limits.rs new file mode 100644 index 00000000000..def9e5ebb52 --- /dev/null +++ b/compiler/rustc_middle/src/middle/limits.rs @@ -0,0 +1,66 @@ +//! Registering limits, recursion_limit, type_length_limit and const_eval_limit +//! +//! There are various parts of the compiler that must impose arbitrary limits +//! on how deeply they recurse to prevent stack overflow. Users can override +//! this via an attribute on the crate like `#![recursion_limit="22"]`. This pass +//! just peeks and looks for that attribute. + +use crate::bug; +use rustc_ast as ast; +use rustc_data_structures::sync::OnceCell; +use rustc_session::{Limit, Session}; +use rustc_span::symbol::{sym, Symbol}; + +use std::num::IntErrorKind; + +pub fn update_limits(sess: &Session, krate: &ast::Crate) { + update_limit(sess, krate, &sess.recursion_limit, sym::recursion_limit, 128); + update_limit(sess, krate, &sess.type_length_limit, sym::type_length_limit, 1048576); + update_limit(sess, krate, &sess.const_eval_limit, sym::const_eval_limit, 1_000_000); +} + +fn update_limit( + sess: &Session, + krate: &ast::Crate, + limit: &OnceCell<Limit>, + name: Symbol, + default: usize, +) { + for attr in &krate.attrs { + if !sess.check_name(attr, name) { + continue; + } + + if let Some(s) = attr.value_str() { + match s.as_str().parse() { + Ok(n) => { + limit.set(Limit::new(n)).unwrap(); + return; + } + Err(e) => { + let mut err = + sess.struct_span_err(attr.span, "`limit` must be a non-negative integer"); + + let value_span = attr + .meta() + .and_then(|meta| meta.name_value_literal().cloned()) + .map(|lit| lit.span) + .unwrap_or(attr.span); + + let error_str = match e.kind() { + IntErrorKind::Overflow => "`limit` is too large", + IntErrorKind::Empty => "`limit` must be a non-negative integer", + IntErrorKind::InvalidDigit => "not a valid integer", + IntErrorKind::Underflow => bug!("`limit` should never underflow"), + IntErrorKind::Zero => bug!("zero is a valid `limit`"), + kind => bug!("unimplemented IntErrorKind variant: {:?}", kind), + }; + + err.span_label(value_span, error_str); + err.emit(); + } + } + } + } + limit.set(Limit::new(default)).unwrap(); +} diff --git a/compiler/rustc_middle/src/middle/mod.rs b/compiler/rustc_middle/src/middle/mod.rs new file mode 100644 index 00000000000..9bc9ca6707a --- /dev/null +++ b/compiler/rustc_middle/src/middle/mod.rs @@ -0,0 +1,34 @@ +pub mod codegen_fn_attrs; +pub mod cstore; +pub mod dependency_format; +pub mod exported_symbols; +pub mod lang_items; +pub mod lib_features { + use rustc_data_structures::fx::{FxHashMap, FxHashSet}; + use rustc_span::symbol::Symbol; + + #[derive(HashStable)] + pub struct LibFeatures { + // A map from feature to stabilisation version. + pub stable: FxHashMap<Symbol, Symbol>, + pub unstable: FxHashSet<Symbol>, + } + + impl LibFeatures { + pub fn to_vec(&self) -> Vec<(Symbol, Option<Symbol>)> { + let mut all_features: Vec<_> = self + .stable + .iter() + .map(|(f, s)| (*f, Some(*s))) + .chain(self.unstable.iter().map(|f| (*f, None))) + .collect(); + all_features.sort_unstable_by_key(|f| f.0.as_str()); + all_features + } + } +} +pub mod limits; +pub mod privacy; +pub mod region; +pub mod resolve_lifetime; +pub mod stability; diff --git a/compiler/rustc_middle/src/middle/privacy.rs b/compiler/rustc_middle/src/middle/privacy.rs new file mode 100644 index 00000000000..4756e83b5e9 --- /dev/null +++ b/compiler/rustc_middle/src/middle/privacy.rs @@ -0,0 +1,65 @@ +//! A pass that checks to make sure private fields and methods aren't used +//! outside their scopes. This pass will also generate a set of exported items +//! which are available for use externally when compiled as a library. + +use rustc_data_structures::fx::FxHashMap; +use rustc_hir::def_id::DefIdSet; +use rustc_hir::HirId; +use rustc_macros::HashStable; +use std::fmt; +use std::hash::Hash; + +// Accessibility levels, sorted in ascending order +#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, HashStable)] +pub enum AccessLevel { + /// Superset of `AccessLevel::Reachable` used to mark impl Trait items. + ReachableFromImplTrait, + /// Exported items + items participating in various kinds of public interfaces, + /// but not directly nameable. For example, if function `fn f() -> T {...}` is + /// public, then type `T` is reachable. Its values can be obtained by other crates + /// even if the type itself is not nameable. + Reachable, + /// Public items + items accessible to other crates with help of `pub use` re-exports + Exported, + /// Items accessible to other crates directly, without help of re-exports + Public, +} + +// Accessibility levels for reachable HIR nodes +#[derive(Clone)] +pub struct AccessLevels<Id = HirId> { + pub map: FxHashMap<Id, AccessLevel>, +} + +impl<Id: Hash + Eq> AccessLevels<Id> { + /// See `AccessLevel::Reachable`. + pub fn is_reachable(&self, id: Id) -> bool { + self.map.get(&id) >= Some(&AccessLevel::Reachable) + } + + /// See `AccessLevel::Exported`. + pub fn is_exported(&self, id: Id) -> bool { + self.map.get(&id) >= Some(&AccessLevel::Exported) + } + + /// See `AccessLevel::Public`. + pub fn is_public(&self, id: Id) -> bool { + self.map.get(&id) >= Some(&AccessLevel::Public) + } +} + +impl<Id: Hash + Eq> Default for AccessLevels<Id> { + fn default() -> Self { + AccessLevels { map: Default::default() } + } +} + +impl<Id: Hash + Eq + fmt::Debug> fmt::Debug for AccessLevels<Id> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(&self.map, f) + } +} + +/// A set containing all exported definitions from external crates. +/// The set does not contain any entries from local crates. +pub type ExternalExports = DefIdSet; diff --git a/compiler/rustc_middle/src/middle/region.rs b/compiler/rustc_middle/src/middle/region.rs new file mode 100644 index 00000000000..4c6ac820604 --- /dev/null +++ b/compiler/rustc_middle/src/middle/region.rs @@ -0,0 +1,490 @@ +//! This file declares the `ScopeTree` type, which describes +//! the parent links in the region hierarchy. +//! +//! For more information about how MIR-based region-checking works, +//! see the [rustc dev guide]. +//! +//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/borrow_check.html + +use crate::ich::{NodeIdHashingMode, StableHashingContext}; +use crate::ty::TyCtxt; +use rustc_hir as hir; +use rustc_hir::Node; + +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_macros::HashStable; +use rustc_span::{Span, DUMMY_SP}; + +use std::fmt; + +/// Represents a statically-describable scope that can be used to +/// bound the lifetime/region for values. +/// +/// `Node(node_id)`: Any AST node that has any scope at all has the +/// `Node(node_id)` scope. Other variants represent special cases not +/// immediately derivable from the abstract syntax tree structure. +/// +/// `DestructionScope(node_id)` represents the scope of destructors +/// implicitly-attached to `node_id` that run immediately after the +/// expression for `node_id` itself. Not every AST node carries a +/// `DestructionScope`, but those that are `terminating_scopes` do; +/// see discussion with `ScopeTree`. +/// +/// `Remainder { block, statement_index }` represents +/// the scope of user code running immediately after the initializer +/// expression for the indexed statement, until the end of the block. +/// +/// So: the following code can be broken down into the scopes beneath: +/// +/// ```text +/// let a = f().g( 'b: { let x = d(); let y = d(); x.h(y) } ) ; +/// +/// +-+ (D12.) +/// +-+ (D11.) +/// +---------+ (R10.) +/// +-+ (D9.) +/// +----------+ (M8.) +/// +----------------------+ (R7.) +/// +-+ (D6.) +/// +----------+ (M5.) +/// +-----------------------------------+ (M4.) +/// +--------------------------------------------------+ (M3.) +/// +--+ (M2.) +/// +-----------------------------------------------------------+ (M1.) +/// +/// (M1.): Node scope of the whole `let a = ...;` statement. +/// (M2.): Node scope of the `f()` expression. +/// (M3.): Node scope of the `f().g(..)` expression. +/// (M4.): Node scope of the block labeled `'b:`. +/// (M5.): Node scope of the `let x = d();` statement +/// (D6.): DestructionScope for temporaries created during M5. +/// (R7.): Remainder scope for block `'b:`, stmt 0 (let x = ...). +/// (M8.): Node scope of the `let y = d();` statement. +/// (D9.): DestructionScope for temporaries created during M8. +/// (R10.): Remainder scope for block `'b:`, stmt 1 (let y = ...). +/// (D11.): DestructionScope for temporaries and bindings from block `'b:`. +/// (D12.): DestructionScope for temporaries created during M1 (e.g., f()). +/// ``` +/// +/// Note that while the above picture shows the destruction scopes +/// as following their corresponding node scopes, in the internal +/// data structures of the compiler the destruction scopes are +/// represented as enclosing parents. This is sound because we use the +/// enclosing parent relationship just to ensure that referenced +/// values live long enough; phrased another way, the starting point +/// of each range is not really the important thing in the above +/// picture, but rather the ending point. +// +// FIXME(pnkfelix): this currently derives `PartialOrd` and `Ord` to +// placate the same deriving in `ty::FreeRegion`, but we may want to +// actually attach a more meaningful ordering to scopes than the one +// generated via deriving here. +#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Copy, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub struct Scope { + pub id: hir::ItemLocalId, + pub data: ScopeData, +} + +impl fmt::Debug for Scope { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + match self.data { + ScopeData::Node => write!(fmt, "Node({:?})", self.id), + ScopeData::CallSite => write!(fmt, "CallSite({:?})", self.id), + ScopeData::Arguments => write!(fmt, "Arguments({:?})", self.id), + ScopeData::Destruction => write!(fmt, "Destruction({:?})", self.id), + ScopeData::Remainder(fsi) => write!( + fmt, + "Remainder {{ block: {:?}, first_statement_index: {}}}", + self.id, + fsi.as_u32(), + ), + } + } +} + +#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Debug, Copy, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub enum ScopeData { + Node, + + /// Scope of the call-site for a function or closure + /// (outlives the arguments as well as the body). + CallSite, + + /// Scope of arguments passed to a function or closure + /// (they outlive its body). + Arguments, + + /// Scope of destructors for temporaries of node-id. + Destruction, + + /// Scope following a `let id = expr;` binding in a block. + Remainder(FirstStatementIndex), +} + +rustc_index::newtype_index! { + /// Represents a subscope of `block` for a binding that is introduced + /// by `block.stmts[first_statement_index]`. Such subscopes represent + /// a suffix of the block. Note that each subscope does not include + /// the initializer expression, if any, for the statement indexed by + /// `first_statement_index`. + /// + /// For example, given `{ let (a, b) = EXPR_1; let c = EXPR_2; ... }`: + /// + /// * The subscope with `first_statement_index == 0` is scope of both + /// `a` and `b`; it does not include EXPR_1, but does include + /// everything after that first `let`. (If you want a scope that + /// includes EXPR_1 as well, then do not use `Scope::Remainder`, + /// but instead another `Scope` that encompasses the whole block, + /// e.g., `Scope::Node`. + /// + /// * The subscope with `first_statement_index == 1` is scope of `c`, + /// and thus does not include EXPR_2, but covers the `...`. + pub struct FirstStatementIndex { + derive [HashStable] + } +} + +// compilation error if size of `ScopeData` is not the same as a `u32` +static_assert_size!(ScopeData, 4); + +impl Scope { + /// Returns a item-local ID associated with this scope. + /// + /// N.B., likely to be replaced as API is refined; e.g., pnkfelix + /// anticipates `fn entry_node_id` and `fn each_exit_node_id`. + pub fn item_local_id(&self) -> hir::ItemLocalId { + self.id + } + + pub fn hir_id(&self, scope_tree: &ScopeTree) -> Option<hir::HirId> { + scope_tree + .root_body + .map(|hir_id| hir::HirId { owner: hir_id.owner, local_id: self.item_local_id() }) + } + + /// Returns the span of this `Scope`. Note that in general the + /// returned span may not correspond to the span of any `NodeId` in + /// the AST. + pub fn span(&self, tcx: TyCtxt<'_>, scope_tree: &ScopeTree) -> Span { + let hir_id = match self.hir_id(scope_tree) { + Some(hir_id) => hir_id, + None => return DUMMY_SP, + }; + let span = tcx.hir().span(hir_id); + if let ScopeData::Remainder(first_statement_index) = self.data { + if let Node::Block(ref blk) = tcx.hir().get(hir_id) { + // Want span for scope starting after the + // indexed statement and ending at end of + // `blk`; reuse span of `blk` and shift `lo` + // forward to end of indexed statement. + // + // (This is the special case alluded to in the + // doc-comment for this method) + + let stmt_span = blk.stmts[first_statement_index.index()].span; + + // To avoid issues with macro-generated spans, the span + // of the statement must be nested in that of the block. + if span.lo() <= stmt_span.lo() && stmt_span.lo() <= span.hi() { + return Span::new(stmt_span.lo(), span.hi(), span.ctxt()); + } + } + } + span + } +} + +pub type ScopeDepth = u32; + +/// The region scope tree encodes information about region relationships. +#[derive(Default, Debug)] +pub struct ScopeTree { + /// If not empty, this body is the root of this region hierarchy. + pub root_body: Option<hir::HirId>, + + /// The parent of the root body owner, if the latter is an + /// an associated const or method, as impls/traits can also + /// have lifetime parameters free in this body. + pub root_parent: Option<hir::HirId>, + + /// Maps from a scope ID to the enclosing scope id; + /// this is usually corresponding to the lexical nesting, though + /// in the case of closures the parent scope is the innermost + /// conditional expression or repeating block. (Note that the + /// enclosing scope ID for the block associated with a closure is + /// the closure itself.) + pub parent_map: FxHashMap<Scope, (Scope, ScopeDepth)>, + + /// Maps from a variable or binding ID to the block in which that + /// variable is declared. + var_map: FxHashMap<hir::ItemLocalId, Scope>, + + /// Maps from a `NodeId` to the associated destruction scope (if any). + destruction_scopes: FxHashMap<hir::ItemLocalId, Scope>, + + /// `rvalue_scopes` includes entries for those expressions whose + /// cleanup scope is larger than the default. The map goes from the + /// expression ID to the cleanup scope id. For rvalues not present in + /// this table, the appropriate cleanup scope is the innermost + /// enclosing statement, conditional expression, or repeating + /// block (see `terminating_scopes`). + /// In constants, None is used to indicate that certain expressions + /// escape into 'static and should have no local cleanup scope. + rvalue_scopes: FxHashMap<hir::ItemLocalId, Option<Scope>>, + + /// Encodes the hierarchy of fn bodies. Every fn body (including + /// closures) forms its own distinct region hierarchy, rooted in + /// the block that is the fn body. This map points from the ID of + /// that root block to the ID of the root block for the enclosing + /// fn, if any. Thus the map structures the fn bodies into a + /// hierarchy based on their lexical mapping. This is used to + /// handle the relationships between regions in a fn and in a + /// closure defined by that fn. See the "Modeling closures" + /// section of the README in infer::region_constraints for + /// more details. + closure_tree: FxHashMap<hir::ItemLocalId, hir::ItemLocalId>, + + /// If there are any `yield` nested within a scope, this map + /// stores the `Span` of the last one and its index in the + /// postorder of the Visitor traversal on the HIR. + /// + /// HIR Visitor postorder indexes might seem like a peculiar + /// thing to care about. but it turns out that HIR bindings + /// and the temporary results of HIR expressions are never + /// storage-live at the end of HIR nodes with postorder indexes + /// lower than theirs, and therefore don't need to be suspended + /// at yield-points at these indexes. + /// + /// For an example, suppose we have some code such as: + /// ```rust,ignore (example) + /// foo(f(), yield y, bar(g())) + /// ``` + /// + /// With the HIR tree (calls numbered for expository purposes) + /// ``` + /// Call#0(foo, [Call#1(f), Yield(y), Call#2(bar, Call#3(g))]) + /// ``` + /// + /// Obviously, the result of `f()` was created before the yield + /// (and therefore needs to be kept valid over the yield) while + /// the result of `g()` occurs after the yield (and therefore + /// doesn't). If we want to infer that, we can look at the + /// postorder traversal: + /// ```plain,ignore + /// `foo` `f` Call#1 `y` Yield `bar` `g` Call#3 Call#2 Call#0 + /// ``` + /// + /// In which we can easily see that `Call#1` occurs before the yield, + /// and `Call#3` after it. + /// + /// To see that this method works, consider: + /// + /// Let `D` be our binding/temporary and `U` be our other HIR node, with + /// `HIR-postorder(U) < HIR-postorder(D)` (in our example, U would be + /// the yield and D would be one of the calls). Let's show that + /// `D` is storage-dead at `U`. + /// + /// Remember that storage-live/storage-dead refers to the state of + /// the *storage*, and does not consider moves/drop flags. + /// + /// Then: + /// 1. From the ordering guarantee of HIR visitors (see + /// `rustc_hir::intravisit`), `D` does not dominate `U`. + /// 2. Therefore, `D` is *potentially* storage-dead at `U` (because + /// we might visit `U` without ever getting to `D`). + /// 3. However, we guarantee that at each HIR point, each + /// binding/temporary is always either always storage-live + /// or always storage-dead. This is what is being guaranteed + /// by `terminating_scopes` including all blocks where the + /// count of executions is not guaranteed. + /// 4. By `2.` and `3.`, `D` is *statically* storage-dead at `U`, + /// QED. + /// + /// This property ought to not on (3) in an essential way -- it + /// is probably still correct even if we have "unrestricted" terminating + /// scopes. However, why use the complicated proof when a simple one + /// works? + /// + /// A subtle thing: `box` expressions, such as `box (&x, yield 2, &y)`. It + /// might seem that a `box` expression creates a `Box<T>` temporary + /// when it *starts* executing, at `HIR-preorder(BOX-EXPR)`. That might + /// be true in the MIR desugaring, but it is not important in the semantics. + /// + /// The reason is that semantically, until the `box` expression returns, + /// the values are still owned by their containing expressions. So + /// we'll see that `&x`. + pub yield_in_scope: FxHashMap<Scope, YieldData>, + + /// The number of visit_expr and visit_pat calls done in the body. + /// Used to sanity check visit_expr/visit_pat call count when + /// calculating generator interiors. + pub body_expr_count: FxHashMap<hir::BodyId, usize>, +} + +#[derive(Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)] +pub struct YieldData { + /// The `Span` of the yield. + pub span: Span, + /// The number of expressions and patterns appearing before the `yield` in the body plus one. + pub expr_and_pat_count: usize, + pub source: hir::YieldSource, +} + +impl ScopeTree { + pub fn record_scope_parent(&mut self, child: Scope, parent: Option<(Scope, ScopeDepth)>) { + debug!("{:?}.parent = {:?}", child, parent); + + if let Some(p) = parent { + let prev = self.parent_map.insert(child, p); + assert!(prev.is_none()); + } + + // Record the destruction scopes for later so we can query them. + if let ScopeData::Destruction = child.data { + self.destruction_scopes.insert(child.item_local_id(), child); + } + } + + pub fn opt_destruction_scope(&self, n: hir::ItemLocalId) -> Option<Scope> { + self.destruction_scopes.get(&n).cloned() + } + + /// Records that `sub_closure` is defined within `sup_closure`. These IDs + /// should be the ID of the block that is the fn body, which is + /// also the root of the region hierarchy for that fn. + pub fn record_closure_parent( + &mut self, + sub_closure: hir::ItemLocalId, + sup_closure: hir::ItemLocalId, + ) { + debug!( + "record_closure_parent(sub_closure={:?}, sup_closure={:?})", + sub_closure, sup_closure + ); + assert!(sub_closure != sup_closure); + let previous = self.closure_tree.insert(sub_closure, sup_closure); + assert!(previous.is_none()); + } + + pub fn record_var_scope(&mut self, var: hir::ItemLocalId, lifetime: Scope) { + debug!("record_var_scope(sub={:?}, sup={:?})", var, lifetime); + assert!(var != lifetime.item_local_id()); + self.var_map.insert(var, lifetime); + } + + pub fn record_rvalue_scope(&mut self, var: hir::ItemLocalId, lifetime: Option<Scope>) { + debug!("record_rvalue_scope(sub={:?}, sup={:?})", var, lifetime); + if let Some(lifetime) = lifetime { + assert!(var != lifetime.item_local_id()); + } + self.rvalue_scopes.insert(var, lifetime); + } + + /// Returns the narrowest scope that encloses `id`, if any. + pub fn opt_encl_scope(&self, id: Scope) -> Option<Scope> { + self.parent_map.get(&id).cloned().map(|(p, _)| p) + } + + /// Returns the lifetime of the local variable `var_id` + pub fn var_scope(&self, var_id: hir::ItemLocalId) -> Scope { + self.var_map + .get(&var_id) + .cloned() + .unwrap_or_else(|| bug!("no enclosing scope for id {:?}", var_id)) + } + + /// Returns the scope when the temp created by `expr_id` will be cleaned up. + pub fn temporary_scope(&self, expr_id: hir::ItemLocalId) -> Option<Scope> { + // Check for a designated rvalue scope. + if let Some(&s) = self.rvalue_scopes.get(&expr_id) { + debug!("temporary_scope({:?}) = {:?} [custom]", expr_id, s); + return s; + } + + // Otherwise, locate the innermost terminating scope + // if there's one. Static items, for instance, won't + // have an enclosing scope, hence no scope will be + // returned. + let mut id = Scope { id: expr_id, data: ScopeData::Node }; + + while let Some(&(p, _)) = self.parent_map.get(&id) { + match p.data { + ScopeData::Destruction => { + debug!("temporary_scope({:?}) = {:?} [enclosing]", expr_id, id); + return Some(id); + } + _ => id = p, + } + } + + debug!("temporary_scope({:?}) = None", expr_id); + None + } + + /// Returns `true` if `subscope` is equal to or is lexically nested inside `superscope`, and + /// `false` otherwise. + pub fn is_subscope_of(&self, subscope: Scope, superscope: Scope) -> bool { + let mut s = subscope; + debug!("is_subscope_of({:?}, {:?})", subscope, superscope); + while superscope != s { + match self.opt_encl_scope(s) { + None => { + debug!("is_subscope_of({:?}, {:?}, s={:?})=false", subscope, superscope, s); + return false; + } + Some(scope) => s = scope, + } + } + + debug!("is_subscope_of({:?}, {:?})=true", subscope, superscope); + + true + } + + /// Checks whether the given scope contains a `yield`. If so, + /// returns `Some((span, expr_count))` with the span of a yield we found and + /// the number of expressions and patterns appearing before the `yield` in the body + 1. + /// If there a are multiple yields in a scope, the one with the highest number is returned. + pub fn yield_in_scope(&self, scope: Scope) -> Option<YieldData> { + self.yield_in_scope.get(&scope).cloned() + } + + /// Gives the number of expressions visited in a body. + /// Used to sanity check visit_expr call count when + /// calculating generator interiors. + pub fn body_expr_count(&self, body_id: hir::BodyId) -> Option<usize> { + self.body_expr_count.get(&body_id).copied() + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for ScopeTree { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let ScopeTree { + root_body, + root_parent, + ref body_expr_count, + ref parent_map, + ref var_map, + ref destruction_scopes, + ref rvalue_scopes, + ref closure_tree, + ref yield_in_scope, + } = *self; + + hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { + root_body.hash_stable(hcx, hasher); + root_parent.hash_stable(hcx, hasher); + }); + + body_expr_count.hash_stable(hcx, hasher); + parent_map.hash_stable(hcx, hasher); + var_map.hash_stable(hcx, hasher); + destruction_scopes.hash_stable(hcx, hasher); + rvalue_scopes.hash_stable(hcx, hasher); + closure_tree.hash_stable(hcx, hasher); + yield_in_scope.hash_stable(hcx, hasher); + } +} diff --git a/compiler/rustc_middle/src/middle/resolve_lifetime.rs b/compiler/rustc_middle/src/middle/resolve_lifetime.rs new file mode 100644 index 00000000000..3d0144e9c8a --- /dev/null +++ b/compiler/rustc_middle/src/middle/resolve_lifetime.rs @@ -0,0 +1,86 @@ +//! Name resolution for lifetimes: type declarations. + +use crate::ty; + +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_hir::{GenericParam, ItemLocalId}; +use rustc_hir::{GenericParamKind, LifetimeParamKind}; +use rustc_macros::HashStable; + +/// The origin of a named lifetime definition. +/// +/// This is used to prevent the usage of in-band lifetimes in `Fn`/`fn` syntax. +#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, HashStable)] +pub enum LifetimeDefOrigin { + // Explicit binders like `fn foo<'a>(x: &'a u8)` or elided like `impl Foo<&u32>` + ExplicitOrElided, + // In-band declarations like `fn foo(x: &'a u8)` + InBand, + // Some kind of erroneous origin + Error, +} + +impl LifetimeDefOrigin { + pub fn from_param(param: &GenericParam<'_>) -> Self { + match param.kind { + GenericParamKind::Lifetime { kind } => match kind { + LifetimeParamKind::InBand => LifetimeDefOrigin::InBand, + LifetimeParamKind::Explicit => LifetimeDefOrigin::ExplicitOrElided, + LifetimeParamKind::Elided => LifetimeDefOrigin::ExplicitOrElided, + LifetimeParamKind::Error => LifetimeDefOrigin::Error, + }, + _ => bug!("expected a lifetime param"), + } + } +} + +#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, HashStable)] +pub enum Region { + Static, + EarlyBound(/* index */ u32, /* lifetime decl */ DefId, LifetimeDefOrigin), + LateBound(ty::DebruijnIndex, /* lifetime decl */ DefId, LifetimeDefOrigin), + LateBoundAnon(ty::DebruijnIndex, /* anon index */ u32), + Free(DefId, /* lifetime decl */ DefId), +} + +/// A set containing, at most, one known element. +/// If two distinct values are inserted into a set, then it +/// becomes `Many`, which can be used to detect ambiguities. +#[derive(Copy, Clone, PartialEq, Eq, TyEncodable, TyDecodable, Debug, HashStable)] +pub enum Set1<T> { + Empty, + One(T), + Many, +} + +impl<T: PartialEq> Set1<T> { + pub fn insert(&mut self, value: T) { + *self = match self { + Set1::Empty => Set1::One(value), + Set1::One(old) if *old == value => return, + _ => Set1::Many, + }; + } +} + +pub type ObjectLifetimeDefault = Set1<Region>; + +/// Maps the id of each lifetime reference to the lifetime decl +/// that it corresponds to. +#[derive(Default, HashStable)] +pub struct ResolveLifetimes { + /// Maps from every use of a named (not anonymous) lifetime to a + /// `Region` describing how that region is bound + pub defs: FxHashMap<LocalDefId, FxHashMap<ItemLocalId, Region>>, + + /// Set of lifetime def ids that are late-bound; a region can + /// be late-bound if (a) it does NOT appear in a where-clause and + /// (b) it DOES appear in the arguments. + pub late_bound: FxHashMap<LocalDefId, FxHashSet<ItemLocalId>>, + + /// For each type and trait definition, maps type parameters + /// to the trait object lifetime defaults computed from them. + pub object_lifetime_defaults: + FxHashMap<LocalDefId, FxHashMap<ItemLocalId, Vec<ObjectLifetimeDefault>>>, +} diff --git a/compiler/rustc_middle/src/middle/stability.rs b/compiler/rustc_middle/src/middle/stability.rs new file mode 100644 index 00000000000..b32eebbb11e --- /dev/null +++ b/compiler/rustc_middle/src/middle/stability.rs @@ -0,0 +1,418 @@ +//! A pass that annotates every item and method with its stability level, +//! propagating default levels lexically from parent to children ast nodes. + +pub use self::StabilityLevel::*; + +use crate::ty::{self, TyCtxt}; +use rustc_ast::CRATE_NODE_ID; +use rustc_attr::{self as attr, ConstStability, Deprecation, Stability}; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_errors::{Applicability, DiagnosticBuilder}; +use rustc_feature::GateIssue; +use rustc_hir as hir; +use rustc_hir::def::DefKind; +use rustc_hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX}; +use rustc_hir::{self, HirId}; +use rustc_session::lint::builtin::{DEPRECATED, DEPRECATED_IN_FUTURE, SOFT_UNSTABLE}; +use rustc_session::lint::{BuiltinLintDiagnostics, Lint, LintBuffer}; +use rustc_session::parse::feature_err_issue; +use rustc_session::{DiagnosticMessageId, Session}; +use rustc_span::symbol::{sym, Symbol}; +use rustc_span::{MultiSpan, Span}; + +use std::num::NonZeroU32; + +#[derive(PartialEq, Clone, Copy, Debug)] +pub enum StabilityLevel { + Unstable, + Stable, +} + +impl StabilityLevel { + pub fn from_attr_level(level: &attr::StabilityLevel) -> Self { + if level.is_stable() { Stable } else { Unstable } + } +} + +/// An entry in the `depr_map`. +#[derive(Clone, HashStable)] +pub struct DeprecationEntry { + /// The metadata of the attribute associated with this entry. + pub attr: Deprecation, + /// The `DefId` where the attr was originally attached. `None` for non-local + /// `DefId`'s. + origin: Option<HirId>, +} + +impl DeprecationEntry { + pub fn local(attr: Deprecation, id: HirId) -> DeprecationEntry { + DeprecationEntry { attr, origin: Some(id) } + } + + pub fn external(attr: Deprecation) -> DeprecationEntry { + DeprecationEntry { attr, origin: None } + } + + pub fn same_origin(&self, other: &DeprecationEntry) -> bool { + match (self.origin, other.origin) { + (Some(o1), Some(o2)) => o1 == o2, + _ => false, + } + } +} + +/// A stability index, giving the stability level for items and methods. +#[derive(HashStable)] +pub struct Index<'tcx> { + /// This is mostly a cache, except the stabilities of local items + /// are filled by the annotator. + pub stab_map: FxHashMap<HirId, &'tcx Stability>, + pub const_stab_map: FxHashMap<HirId, &'tcx ConstStability>, + pub depr_map: FxHashMap<HirId, DeprecationEntry>, + + /// Maps for each crate whether it is part of the staged API. + pub staged_api: FxHashMap<CrateNum, bool>, + + /// Features enabled for this crate. + pub active_features: FxHashSet<Symbol>, +} + +impl<'tcx> Index<'tcx> { + pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> { + self.stab_map.get(&id).cloned() + } + + pub fn local_const_stability(&self, id: HirId) -> Option<&'tcx ConstStability> { + self.const_stab_map.get(&id).cloned() + } + + pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> { + self.depr_map.get(&id).cloned() + } +} + +pub fn report_unstable( + sess: &Session, + feature: Symbol, + reason: Option<Symbol>, + issue: Option<NonZeroU32>, + is_soft: bool, + span: Span, + soft_handler: impl FnOnce(&'static Lint, Span, &str), +) { + let msg = match reason { + Some(r) => format!("use of unstable library feature '{}': {}", feature, r), + None => format!("use of unstable library feature '{}'", &feature), + }; + + let msp: MultiSpan = span.into(); + let sm = &sess.parse_sess.source_map(); + let span_key = msp.primary_span().and_then(|sp: Span| { + if !sp.is_dummy() { + let file = sm.lookup_char_pos(sp.lo()).file; + if file.is_imported() { None } else { Some(span) } + } else { + None + } + }); + + let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone()); + let fresh = sess.one_time_diagnostics.borrow_mut().insert(error_id); + if fresh { + if is_soft { + soft_handler(SOFT_UNSTABLE, span, &msg) + } else { + feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg) + .emit(); + } + } +} + +/// Checks whether an item marked with `deprecated(since="X")` is currently +/// deprecated (i.e., whether X is not greater than the current rustc version). +pub fn deprecation_in_effect(is_since_rustc_version: bool, since: Option<&str>) -> bool { + let since = if let Some(since) = since { + if is_since_rustc_version { + since + } else { + // We assume that the deprecation is in effect if it's not a + // rustc version. + return true; + } + } else { + // If since attribute is not set, then we're definitely in effect. + return true; + }; + fn parse_version(ver: &str) -> Vec<u32> { + // We ignore non-integer components of the version (e.g., "nightly"). + ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect() + } + + if let Some(rustc) = option_env!("CFG_RELEASE") { + let since: Vec<u32> = parse_version(&since); + let rustc: Vec<u32> = parse_version(rustc); + // We simply treat invalid `since` attributes as relating to a previous + // Rust version, thus always displaying the warning. + if since.len() != 3 { + return true; + } + since <= rustc + } else { + // By default, a deprecation warning applies to + // the current version of the compiler. + true + } +} + +pub fn deprecation_suggestion( + diag: &mut DiagnosticBuilder<'_>, + kind: &str, + suggestion: Option<Symbol>, + span: Span, +) { + if let Some(suggestion) = suggestion { + diag.span_suggestion( + span, + &format!("replace the use of the deprecated {}", kind), + suggestion.to_string(), + Applicability::MachineApplicable, + ); + } +} + +pub fn deprecation_message(depr: &Deprecation, kind: &str, path: &str) -> (String, &'static Lint) { + let (message, lint) = if deprecation_in_effect( + depr.is_since_rustc_version, + depr.since.map(Symbol::as_str).as_deref(), + ) { + (format!("use of deprecated {} `{}`", kind, path), DEPRECATED) + } else { + ( + format!( + "use of {} `{}` that will be deprecated in future version {}", + kind, + path, + depr.since.unwrap() + ), + DEPRECATED_IN_FUTURE, + ) + }; + let message = match depr.note { + Some(reason) => format!("{}: {}", message, reason), + None => message, + }; + (message, lint) +} + +pub fn early_report_deprecation( + lint_buffer: &'a mut LintBuffer, + message: &str, + suggestion: Option<Symbol>, + lint: &'static Lint, + span: Span, +) { + if span.in_derive_expansion() { + return; + } + + let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span); + lint_buffer.buffer_lint_with_diagnostic(lint, CRATE_NODE_ID, span, message, diag); +} + +fn late_report_deprecation( + tcx: TyCtxt<'_>, + message: &str, + suggestion: Option<Symbol>, + lint: &'static Lint, + span: Span, + hir_id: HirId, + def_id: DefId, +) { + if span.in_derive_expansion() { + return; + } + + tcx.struct_span_lint_hir(lint, hir_id, span, |lint| { + let mut diag = lint.build(message); + if let hir::Node::Expr(_) = tcx.hir().get(hir_id) { + let kind = tcx.def_kind(def_id).descr(def_id); + deprecation_suggestion(&mut diag, kind, suggestion, span); + } + diag.emit() + }); +} + +/// Result of `TyCtxt::eval_stability`. +pub enum EvalResult { + /// We can use the item because it is stable or we provided the + /// corresponding feature gate. + Allow, + /// We cannot use the item because it is unstable and we did not provide the + /// corresponding feature gate. + Deny { feature: Symbol, reason: Option<Symbol>, issue: Option<NonZeroU32>, is_soft: bool }, + /// The item does not have the `#[stable]` or `#[unstable]` marker assigned. + Unmarked, +} + +// See issue #38412. +fn skip_stability_check_due_to_privacy(tcx: TyCtxt<'_>, mut def_id: DefId) -> bool { + // Check if `def_id` is a trait method. + match tcx.def_kind(def_id) { + DefKind::AssocFn | DefKind::AssocTy | DefKind::AssocConst => { + if let ty::TraitContainer(trait_def_id) = tcx.associated_item(def_id).container { + // Trait methods do not declare visibility (even + // for visibility info in cstore). Use containing + // trait instead, so methods of `pub` traits are + // themselves considered `pub`. + def_id = trait_def_id; + } + } + _ => {} + } + + let visibility = tcx.visibility(def_id); + + match visibility { + // Must check stability for `pub` items. + ty::Visibility::Public => false, + + // These are not visible outside crate; therefore + // stability markers are irrelevant, if even present. + ty::Visibility::Restricted(..) | ty::Visibility::Invisible => true, + } +} + +impl<'tcx> TyCtxt<'tcx> { + /// Evaluates the stability of an item. + /// + /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding + /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending + /// unstable feature otherwise. + /// + /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been + /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to + /// `id`. + pub fn eval_stability(self, def_id: DefId, id: Option<HirId>, span: Span) -> EvalResult { + // Deprecated attributes apply in-crate and cross-crate. + if let Some(id) = id { + if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) { + let parent_def_id = self.hir().local_def_id(self.hir().get_parent_item(id)); + let skip = self + .lookup_deprecation_entry(parent_def_id.to_def_id()) + .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry)); + + // #[deprecated] doesn't emit a notice if we're not on the + // topmost deprecation. For example, if a struct is deprecated, + // the use of a field won't be linted. + // + // #[rustc_deprecated] however wants to emit down the whole + // hierarchy. + if !skip || depr_entry.attr.is_since_rustc_version { + let path = &self.def_path_str(def_id); + let kind = self.def_kind(def_id).descr(def_id); + let (message, lint) = deprecation_message(&depr_entry.attr, kind, path); + late_report_deprecation( + self, + &message, + depr_entry.attr.suggestion, + lint, + span, + id, + def_id, + ); + } + }; + } + + let is_staged_api = + self.lookup_stability(DefId { index: CRATE_DEF_INDEX, ..def_id }).is_some(); + if !is_staged_api { + return EvalResult::Allow; + } + + let stability = self.lookup_stability(def_id); + debug!( + "stability: \ + inspecting def_id={:?} span={:?} of stability={:?}", + def_id, span, stability + ); + + // Only the cross-crate scenario matters when checking unstable APIs + let cross_crate = !def_id.is_local(); + if !cross_crate { + return EvalResult::Allow; + } + + // Issue #38412: private items lack stability markers. + if skip_stability_check_due_to_privacy(self, def_id) { + return EvalResult::Allow; + } + + match stability { + Some(&Stability { + level: attr::Unstable { reason, issue, is_soft }, feature, .. + }) => { + if span.allows_unstable(feature) { + debug!("stability: skipping span={:?} since it is internal", span); + return EvalResult::Allow; + } + if self.stability().active_features.contains(&feature) { + return EvalResult::Allow; + } + + // When we're compiling the compiler itself we may pull in + // crates from crates.io, but those crates may depend on other + // crates also pulled in from crates.io. We want to ideally be + // able to compile everything without requiring upstream + // modifications, so in the case that this looks like a + // `rustc_private` crate (e.g., a compiler crate) and we also have + // the `-Z force-unstable-if-unmarked` flag present (we're + // compiling a compiler crate), then let this missing feature + // annotation slide. + if feature == sym::rustc_private && issue == NonZeroU32::new(27812) { + if self.sess.opts.debugging_opts.force_unstable_if_unmarked { + return EvalResult::Allow; + } + } + + EvalResult::Deny { feature, reason, issue, is_soft } + } + Some(_) => { + // Stable APIs are always ok to call and deprecated APIs are + // handled by the lint emitting logic above. + EvalResult::Allow + } + None => EvalResult::Unmarked, + } + } + + /// Checks if an item is stable or error out. + /// + /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not + /// exist, emits an error. + /// + /// Additionally, this function will also check if the item is deprecated. If so, and `id` is + /// not `None`, a deprecated lint attached to `id` will be emitted. + pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) { + let soft_handler = |lint, span, msg: &_| { + self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, |lint| { + lint.build(msg).emit() + }) + }; + match self.eval_stability(def_id, id, span) { + EvalResult::Allow => {} + EvalResult::Deny { feature, reason, issue, is_soft } => { + report_unstable(self.sess, feature, reason, issue, is_soft, span, soft_handler) + } + EvalResult::Unmarked => { + // The API could be uncallable for other reasons, for example when a private module + // was referenced. + self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id)); + } + } + } + + pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> { + self.lookup_deprecation_entry(id).map(|depr| depr.attr) + } +} diff --git a/compiler/rustc_middle/src/mir/coverage/mod.rs b/compiler/rustc_middle/src/mir/coverage/mod.rs new file mode 100644 index 00000000000..ce311c2ee52 --- /dev/null +++ b/compiler/rustc_middle/src/mir/coverage/mod.rs @@ -0,0 +1,105 @@ +//! Metadata from source code coverage analysis and instrumentation. + +use rustc_macros::HashStable; +use rustc_span::Symbol; + +use std::cmp::Ord; +use std::fmt::{self, Debug, Formatter}; + +rustc_index::newtype_index! { + pub struct ExpressionOperandId { + derive [HashStable] + DEBUG_FORMAT = "ExpressionOperandId({})", + MAX = 0xFFFF_FFFF, + } +} + +rustc_index::newtype_index! { + pub struct CounterValueReference { + derive [HashStable] + DEBUG_FORMAT = "CounterValueReference({})", + MAX = 0xFFFF_FFFF, + } +} + +rustc_index::newtype_index! { + pub struct InjectedExpressionIndex { + derive [HashStable] + DEBUG_FORMAT = "InjectedExpressionIndex({})", + MAX = 0xFFFF_FFFF, + } +} + +rustc_index::newtype_index! { + pub struct MappedExpressionIndex { + derive [HashStable] + DEBUG_FORMAT = "MappedExpressionIndex({})", + MAX = 0xFFFF_FFFF, + } +} + +impl From<CounterValueReference> for ExpressionOperandId { + #[inline] + fn from(v: CounterValueReference) -> ExpressionOperandId { + ExpressionOperandId::from(v.as_u32()) + } +} + +impl From<InjectedExpressionIndex> for ExpressionOperandId { + #[inline] + fn from(v: InjectedExpressionIndex) -> ExpressionOperandId { + ExpressionOperandId::from(v.as_u32()) + } +} + +#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub enum CoverageKind { + Counter { + function_source_hash: u64, + id: CounterValueReference, + }, + Expression { + id: InjectedExpressionIndex, + lhs: ExpressionOperandId, + op: Op, + rhs: ExpressionOperandId, + }, + Unreachable, +} + +impl CoverageKind { + pub fn as_operand_id(&self) -> ExpressionOperandId { + match *self { + CoverageKind::Counter { id, .. } => ExpressionOperandId::from(id), + CoverageKind::Expression { id, .. } => ExpressionOperandId::from(id), + CoverageKind::Unreachable => { + bug!("Unreachable coverage cannot be part of an expression") + } + } + } +} + +#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, PartialEq, Eq, PartialOrd, Ord)] +pub struct CodeRegion { + pub file_name: Symbol, + pub start_line: u32, + pub start_col: u32, + pub end_line: u32, + pub end_col: u32, +} + +impl Debug for CodeRegion { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + write!( + fmt, + "{}:{}:{} - {}:{}", + self.file_name, self.start_line, self.start_col, self.end_line, self.end_col + ) + } +} + +#[derive(Copy, Clone, Debug, PartialEq, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub enum Op { + Subtract, + Add, +} diff --git a/compiler/rustc_middle/src/mir/interpret/allocation.rs b/compiler/rustc_middle/src/mir/interpret/allocation.rs new file mode 100644 index 00000000000..505939d56ed --- /dev/null +++ b/compiler/rustc_middle/src/mir/interpret/allocation.rs @@ -0,0 +1,887 @@ +//! The virtual memory representation of the MIR interpreter. + +use std::borrow::Cow; +use std::convert::TryFrom; +use std::iter; +use std::ops::{Deref, DerefMut, Range}; + +use rustc_ast::Mutability; +use rustc_data_structures::sorted_map::SortedMap; +use rustc_target::abi::{Align, HasDataLayout, Size}; + +use super::{ + read_target_uint, write_target_uint, AllocId, InterpResult, Pointer, Scalar, ScalarMaybeUninit, + UninitBytesAccess, +}; + +#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub struct Allocation<Tag = (), Extra = ()> { + /// The actual bytes of the allocation. + /// Note that the bytes of a pointer represent the offset of the pointer. + bytes: Vec<u8>, + /// Maps from byte addresses to extra data for each pointer. + /// Only the first byte of a pointer is inserted into the map; i.e., + /// every entry in this map applies to `pointer_size` consecutive bytes starting + /// at the given offset. + relocations: Relocations<Tag>, + /// Denotes which part of this allocation is initialized. + init_mask: InitMask, + /// The size of the allocation. Currently, must always equal `bytes.len()`. + pub size: Size, + /// The alignment of the allocation to detect unaligned reads. + /// (`Align` guarantees that this is a power of two.) + pub align: Align, + /// `true` if the allocation is mutable. + /// Also used by codegen to determine if a static should be put into mutable memory, + /// which happens for `static mut` and `static` with interior mutability. + pub mutability: Mutability, + /// Extra state for the machine. + pub extra: Extra, +} + +pub trait AllocationExtra<Tag>: ::std::fmt::Debug + Clone { + // There is no constructor in here because the constructor's type depends + // on `MemoryKind`, and making things sufficiently generic leads to painful + // inference failure. + + /// Hook for performing extra checks on a memory read access. + /// + /// Takes read-only access to the allocation so we can keep all the memory read + /// operations take `&self`. Use a `RefCell` in `AllocExtra` if you + /// need to mutate. + #[inline(always)] + fn memory_read( + _alloc: &Allocation<Tag, Self>, + _ptr: Pointer<Tag>, + _size: Size, + ) -> InterpResult<'tcx> { + Ok(()) + } + + /// Hook for performing extra checks on a memory write access. + #[inline(always)] + fn memory_written( + _alloc: &mut Allocation<Tag, Self>, + _ptr: Pointer<Tag>, + _size: Size, + ) -> InterpResult<'tcx> { + Ok(()) + } + + /// Hook for performing extra checks on a memory deallocation. + /// `size` will be the size of the allocation. + #[inline(always)] + fn memory_deallocated( + _alloc: &mut Allocation<Tag, Self>, + _ptr: Pointer<Tag>, + _size: Size, + ) -> InterpResult<'tcx> { + Ok(()) + } +} + +// For `Tag = ()` and no extra state, we have a trivial implementation. +impl AllocationExtra<()> for () {} + +// The constructors are all without extra; the extra gets added by a machine hook later. +impl<Tag> Allocation<Tag> { + /// Creates a read-only allocation initialized by the given bytes + pub fn from_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>, align: Align) -> Self { + let bytes = slice.into().into_owned(); + let size = Size::from_bytes(bytes.len()); + Self { + bytes, + relocations: Relocations::new(), + init_mask: InitMask::new(size, true), + size, + align, + mutability: Mutability::Not, + extra: (), + } + } + + pub fn from_byte_aligned_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>) -> Self { + Allocation::from_bytes(slice, Align::from_bytes(1).unwrap()) + } + + pub fn uninit(size: Size, align: Align) -> Self { + Allocation { + bytes: vec![0; size.bytes_usize()], + relocations: Relocations::new(), + init_mask: InitMask::new(size, false), + size, + align, + mutability: Mutability::Mut, + extra: (), + } + } +} + +impl Allocation<(), ()> { + /// Add Tag and Extra fields + pub fn with_tags_and_extra<T, E>( + self, + mut tagger: impl FnMut(AllocId) -> T, + extra: E, + ) -> Allocation<T, E> { + Allocation { + bytes: self.bytes, + size: self.size, + relocations: Relocations::from_presorted( + self.relocations + .iter() + // The allocations in the relocations (pointers stored *inside* this allocation) + // all get the base pointer tag. + .map(|&(offset, ((), alloc))| { + let tag = tagger(alloc); + (offset, (tag, alloc)) + }) + .collect(), + ), + init_mask: self.init_mask, + align: self.align, + mutability: self.mutability, + extra, + } + } +} + +/// Raw accessors. Provide access to otherwise private bytes. +impl<Tag, Extra> Allocation<Tag, Extra> { + pub fn len(&self) -> usize { + self.size.bytes_usize() + } + + /// Looks at a slice which may describe uninitialized bytes or describe a relocation. This differs + /// from `get_bytes_with_uninit_and_ptr` in that it does no relocation checks (even on the + /// edges) at all. It further ignores `AllocationExtra` callbacks. + /// This must not be used for reads affecting the interpreter execution. + pub fn inspect_with_uninit_and_ptr_outside_interpreter(&self, range: Range<usize>) -> &[u8] { + &self.bytes[range] + } + + /// Returns the mask indicating which bytes are initialized. + pub fn init_mask(&self) -> &InitMask { + &self.init_mask + } + + /// Returns the relocation list. + pub fn relocations(&self) -> &Relocations<Tag> { + &self.relocations + } +} + +/// Byte accessors. +impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> { + /// Just a small local helper function to avoid a bit of code repetition. + /// Returns the range of this allocation that was meant. + #[inline] + fn check_bounds(&self, offset: Size, size: Size) -> Range<usize> { + let end = offset + size; // This does overflow checking. + let end = usize::try_from(end.bytes()).expect("access too big for this host architecture"); + assert!( + end <= self.len(), + "Out-of-bounds access at offset {}, size {} in allocation of size {}", + offset.bytes(), + size.bytes(), + self.len() + ); + offset.bytes_usize()..end + } + + /// The last argument controls whether we error out when there are uninitialized + /// or pointer bytes. You should never call this, call `get_bytes` or + /// `get_bytes_with_uninit_and_ptr` instead, + /// + /// This function also guarantees that the resulting pointer will remain stable + /// even when new allocations are pushed to the `HashMap`. `copy_repeatedly` relies + /// on that. + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + fn get_bytes_internal( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + check_init_and_ptr: bool, + ) -> InterpResult<'tcx, &[u8]> { + let range = self.check_bounds(ptr.offset, size); + + if check_init_and_ptr { + self.check_init(ptr, size)?; + self.check_relocations(cx, ptr, size)?; + } else { + // We still don't want relocations on the *edges*. + self.check_relocation_edges(cx, ptr, size)?; + } + + AllocationExtra::memory_read(self, ptr, size)?; + + Ok(&self.bytes[range]) + } + + /// Checks that these bytes are initialized and not pointer bytes, and then return them + /// as a slice. + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + /// Most likely, you want to use the `PlaceTy` and `OperandTy`-based methods + /// on `InterpCx` instead. + #[inline] + pub fn get_bytes( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + ) -> InterpResult<'tcx, &[u8]> { + self.get_bytes_internal(cx, ptr, size, true) + } + + /// It is the caller's responsibility to handle uninitialized and pointer bytes. + /// However, this still checks that there are no relocations on the *edges*. + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + #[inline] + pub fn get_bytes_with_uninit_and_ptr( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + ) -> InterpResult<'tcx, &[u8]> { + self.get_bytes_internal(cx, ptr, size, false) + } + + /// Just calling this already marks everything as defined and removes relocations, + /// so be sure to actually put data there! + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + /// Most likely, you want to use the `PlaceTy` and `OperandTy`-based methods + /// on `InterpCx` instead. + pub fn get_bytes_mut( + &mut self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + ) -> InterpResult<'tcx, &mut [u8]> { + let range = self.check_bounds(ptr.offset, size); + + self.mark_init(ptr, size, true); + self.clear_relocations(cx, ptr, size)?; + + AllocationExtra::memory_written(self, ptr, size)?; + + Ok(&mut self.bytes[range]) + } +} + +/// Reading and writing. +impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> { + /// Reads bytes until a `0` is encountered. Will error if the end of the allocation is reached + /// before a `0` is found. + /// + /// Most likely, you want to call `Memory::read_c_str` instead of this method. + pub fn read_c_str( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + ) -> InterpResult<'tcx, &[u8]> { + let offset = ptr.offset.bytes_usize(); + Ok(match self.bytes[offset..].iter().position(|&c| c == 0) { + Some(size) => { + let size_with_null = Size::from_bytes(size) + Size::from_bytes(1); + // Go through `get_bytes` for checks and AllocationExtra hooks. + // We read the null, so we include it in the request, but we want it removed + // from the result, so we do subslicing. + &self.get_bytes(cx, ptr, size_with_null)?[..size] + } + // This includes the case where `offset` is out-of-bounds to begin with. + None => throw_ub!(UnterminatedCString(ptr.erase_tag())), + }) + } + + /// Validates that `ptr.offset` and `ptr.offset + size` do not point to the middle of a + /// relocation. If `allow_uninit_and_ptr` is `false`, also enforces that the memory in the + /// given range contains neither relocations nor uninitialized bytes. + pub fn check_bytes( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + allow_uninit_and_ptr: bool, + ) -> InterpResult<'tcx> { + // Check bounds and relocations on the edges. + self.get_bytes_with_uninit_and_ptr(cx, ptr, size)?; + // Check uninit and ptr. + if !allow_uninit_and_ptr { + self.check_init(ptr, size)?; + self.check_relocations(cx, ptr, size)?; + } + Ok(()) + } + + /// Writes `src` to the memory starting at `ptr.offset`. + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + /// Most likely, you want to call `Memory::write_bytes` instead of this method. + pub fn write_bytes( + &mut self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + src: impl IntoIterator<Item = u8>, + ) -> InterpResult<'tcx> { + let mut src = src.into_iter(); + let (lower, upper) = src.size_hint(); + let len = upper.expect("can only write bounded iterators"); + assert_eq!(lower, len, "can only write iterators with a precise length"); + let bytes = self.get_bytes_mut(cx, ptr, Size::from_bytes(len))?; + // `zip` would stop when the first iterator ends; we want to definitely + // cover all of `bytes`. + for dest in bytes { + *dest = src.next().expect("iterator was shorter than it said it would be"); + } + src.next().expect_none("iterator was longer than it said it would be"); + Ok(()) + } + + /// Reads a *non-ZST* scalar. + /// + /// ZSTs can't be read for two reasons: + /// * byte-order cannot work with zero-element buffers; + /// * in order to obtain a `Pointer`, we need to check for ZSTness anyway due to integer + /// pointers being valid for ZSTs. + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + /// Most likely, you want to call `InterpCx::read_scalar` instead of this method. + pub fn read_scalar( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + ) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> { + // `get_bytes_unchecked` tests relocation edges. + let bytes = self.get_bytes_with_uninit_and_ptr(cx, ptr, size)?; + // Uninit check happens *after* we established that the alignment is correct. + // We must not return `Ok()` for unaligned pointers! + if self.is_init(ptr, size).is_err() { + // This inflates uninitialized bytes to the entire scalar, even if only a few + // bytes are uninitialized. + return Ok(ScalarMaybeUninit::Uninit); + } + // Now we do the actual reading. + let bits = read_target_uint(cx.data_layout().endian, bytes).unwrap(); + // See if we got a pointer. + if size != cx.data_layout().pointer_size { + // *Now*, we better make sure that the inside is free of relocations too. + self.check_relocations(cx, ptr, size)?; + } else { + if let Some(&(tag, alloc_id)) = self.relocations.get(&ptr.offset) { + let ptr = Pointer::new_with_tag(alloc_id, Size::from_bytes(bits), tag); + return Ok(ScalarMaybeUninit::Scalar(ptr.into())); + } + } + // We don't. Just return the bits. + Ok(ScalarMaybeUninit::Scalar(Scalar::from_uint(bits, size))) + } + + /// Reads a pointer-sized scalar. + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + /// Most likely, you want to call `InterpCx::read_scalar` instead of this method. + pub fn read_ptr_sized( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + ) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> { + self.read_scalar(cx, ptr, cx.data_layout().pointer_size) + } + + /// Writes a *non-ZST* scalar. + /// + /// ZSTs can't be read for two reasons: + /// * byte-order cannot work with zero-element buffers; + /// * in order to obtain a `Pointer`, we need to check for ZSTness anyway due to integer + /// pointers being valid for ZSTs. + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + /// Most likely, you want to call `InterpCx::write_scalar` instead of this method. + pub fn write_scalar( + &mut self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + val: ScalarMaybeUninit<Tag>, + type_size: Size, + ) -> InterpResult<'tcx> { + let val = match val { + ScalarMaybeUninit::Scalar(scalar) => scalar, + ScalarMaybeUninit::Uninit => { + self.mark_init(ptr, type_size, false); + return Ok(()); + } + }; + + let bytes = match val.to_bits_or_ptr(type_size, cx) { + Err(val) => u128::from(val.offset.bytes()), + Ok(data) => data, + }; + + let endian = cx.data_layout().endian; + let dst = self.get_bytes_mut(cx, ptr, type_size)?; + write_target_uint(endian, dst, bytes).unwrap(); + + // See if we have to also write a relocation. + if let Scalar::Ptr(val) = val { + self.relocations.insert(ptr.offset, (val.tag, val.alloc_id)); + } + + Ok(()) + } + + /// Writes a pointer-sized scalar. + /// + /// It is the caller's responsibility to check bounds and alignment beforehand. + /// Most likely, you want to call `InterpCx::write_scalar` instead of this method. + pub fn write_ptr_sized( + &mut self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + val: ScalarMaybeUninit<Tag>, + ) -> InterpResult<'tcx> { + let ptr_size = cx.data_layout().pointer_size; + self.write_scalar(cx, ptr, val, ptr_size) + } +} + +/// Relocations. +impl<'tcx, Tag: Copy, Extra> Allocation<Tag, Extra> { + /// Returns all relocations overlapping with the given pointer-offset pair. + pub fn get_relocations( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + ) -> &[(Size, (Tag, AllocId))] { + // We have to go back `pointer_size - 1` bytes, as that one would still overlap with + // the beginning of this range. + let start = ptr.offset.bytes().saturating_sub(cx.data_layout().pointer_size.bytes() - 1); + let end = ptr.offset + size; // This does overflow checking. + self.relocations.range(Size::from_bytes(start)..end) + } + + /// Checks that there are no relocations overlapping with the given range. + #[inline(always)] + fn check_relocations( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + ) -> InterpResult<'tcx> { + if self.get_relocations(cx, ptr, size).is_empty() { + Ok(()) + } else { + throw_unsup!(ReadPointerAsBytes) + } + } + + /// Removes all relocations inside the given range. + /// If there are relocations overlapping with the edges, they + /// are removed as well *and* the bytes they cover are marked as + /// uninitialized. This is a somewhat odd "spooky action at a distance", + /// but it allows strictly more code to run than if we would just error + /// immediately in that case. + fn clear_relocations( + &mut self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + ) -> InterpResult<'tcx> { + // Find the start and end of the given range and its outermost relocations. + let (first, last) = { + // Find all relocations overlapping the given range. + let relocations = self.get_relocations(cx, ptr, size); + if relocations.is_empty() { + return Ok(()); + } + + ( + relocations.first().unwrap().0, + relocations.last().unwrap().0 + cx.data_layout().pointer_size, + ) + }; + let start = ptr.offset; + let end = start + size; // `Size` addition + + // Mark parts of the outermost relocations as uninitialized if they partially fall outside the + // given range. + if first < start { + self.init_mask.set_range(first, start, false); + } + if last > end { + self.init_mask.set_range(end, last, false); + } + + // Forget all the relocations. + self.relocations.remove_range(first..last); + + Ok(()) + } + + /// Errors if there are relocations overlapping with the edges of the + /// given memory range. + #[inline] + fn check_relocation_edges( + &self, + cx: &impl HasDataLayout, + ptr: Pointer<Tag>, + size: Size, + ) -> InterpResult<'tcx> { + self.check_relocations(cx, ptr, Size::ZERO)?; + self.check_relocations(cx, ptr.offset(size, cx)?, Size::ZERO)?; + Ok(()) + } +} + +/// Uninitialized bytes. +impl<'tcx, Tag: Copy, Extra> Allocation<Tag, Extra> { + /// Checks whether the given range is entirely initialized. + /// + /// Returns `Ok(())` if it's initialized. Otherwise returns the range of byte + /// indexes of the first contiguous uninitialized access. + fn is_init(&self, ptr: Pointer<Tag>, size: Size) -> Result<(), Range<Size>> { + self.init_mask.is_range_initialized(ptr.offset, ptr.offset + size) // `Size` addition + } + + /// Checks that a range of bytes is initialized. If not, returns the `InvalidUninitBytes` + /// error which will report the first range of bytes which is uninitialized. + fn check_init(&self, ptr: Pointer<Tag>, size: Size) -> InterpResult<'tcx> { + self.is_init(ptr, size).or_else(|idx_range| { + throw_ub!(InvalidUninitBytes(Some(Box::new(UninitBytesAccess { + access_ptr: ptr.erase_tag(), + access_size: size, + uninit_ptr: Pointer::new(ptr.alloc_id, idx_range.start), + uninit_size: idx_range.end - idx_range.start, // `Size` subtraction + })))) + }) + } + + pub fn mark_init(&mut self, ptr: Pointer<Tag>, size: Size, is_init: bool) { + if size.bytes() == 0 { + return; + } + self.init_mask.set_range(ptr.offset, ptr.offset + size, is_init); + } +} + +/// Run-length encoding of the uninit mask. +/// Used to copy parts of a mask multiple times to another allocation. +pub struct InitMaskCompressed { + /// Whether the first range is initialized. + initial: bool, + /// The lengths of ranges that are run-length encoded. + /// The initialization state of the ranges alternate starting with `initial`. + ranges: smallvec::SmallVec<[u64; 1]>, +} + +impl InitMaskCompressed { + pub fn no_bytes_init(&self) -> bool { + // The `ranges` are run-length encoded and of alternating initialization state. + // So if `ranges.len() > 1` then the second block is an initialized range. + !self.initial && self.ranges.len() == 1 + } +} + +/// Transferring the initialization mask to other allocations. +impl<Tag, Extra> Allocation<Tag, Extra> { + /// Creates a run-length encoding of the initialization mask. + pub fn compress_uninit_range(&self, src: Pointer<Tag>, size: Size) -> InitMaskCompressed { + // Since we are copying `size` bytes from `src` to `dest + i * size` (`for i in 0..repeat`), + // a naive initialization mask copying algorithm would repeatedly have to read the initialization mask from + // the source and write it to the destination. Even if we optimized the memory accesses, + // we'd be doing all of this `repeat` times. + // Therefore we precompute a compressed version of the initialization mask of the source value and + // then write it back `repeat` times without computing any more information from the source. + + // A precomputed cache for ranges of initialized / uninitialized bits + // 0000010010001110 will become + // `[5, 1, 2, 1, 3, 3, 1]`, + // where each element toggles the state. + + let mut ranges = smallvec::SmallVec::<[u64; 1]>::new(); + let initial = self.init_mask.get(src.offset); + let mut cur_len = 1; + let mut cur = initial; + + for i in 1..size.bytes() { + // FIXME: optimize to bitshift the current uninitialized block's bits and read the top bit. + if self.init_mask.get(src.offset + Size::from_bytes(i)) == cur { + cur_len += 1; + } else { + ranges.push(cur_len); + cur_len = 1; + cur = !cur; + } + } + + ranges.push(cur_len); + + InitMaskCompressed { ranges, initial } + } + + /// Applies multiple instances of the run-length encoding to the initialization mask. + pub fn mark_compressed_init_range( + &mut self, + defined: &InitMaskCompressed, + dest: Pointer<Tag>, + size: Size, + repeat: u64, + ) { + // An optimization where we can just overwrite an entire range of initialization + // bits if they are going to be uniformly `1` or `0`. + if defined.ranges.len() <= 1 { + self.init_mask.set_range_inbounds( + dest.offset, + dest.offset + size * repeat, // `Size` operations + defined.initial, + ); + return; + } + + for mut j in 0..repeat { + j *= size.bytes(); + j += dest.offset.bytes(); + let mut cur = defined.initial; + for range in &defined.ranges { + let old_j = j; + j += range; + self.init_mask.set_range_inbounds( + Size::from_bytes(old_j), + Size::from_bytes(j), + cur, + ); + cur = !cur; + } + } + } +} + +/// Relocations. +#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] +pub struct Relocations<Tag = (), Id = AllocId>(SortedMap<Size, (Tag, Id)>); + +impl<Tag, Id> Relocations<Tag, Id> { + pub fn new() -> Self { + Relocations(SortedMap::new()) + } + + // The caller must guarantee that the given relocations are already sorted + // by address and contain no duplicates. + pub fn from_presorted(r: Vec<(Size, (Tag, Id))>) -> Self { + Relocations(SortedMap::from_presorted_elements(r)) + } +} + +impl<Tag> Deref for Relocations<Tag> { + type Target = SortedMap<Size, (Tag, AllocId)>; + + fn deref(&self) -> &Self::Target { + &self.0 + } +} + +impl<Tag> DerefMut for Relocations<Tag> { + fn deref_mut(&mut self) -> &mut Self::Target { + &mut self.0 + } +} + +/// A partial, owned list of relocations to transfer into another allocation. +pub struct AllocationRelocations<Tag> { + relative_relocations: Vec<(Size, (Tag, AllocId))>, +} + +impl<Tag: Copy, Extra> Allocation<Tag, Extra> { + pub fn prepare_relocation_copy( + &self, + cx: &impl HasDataLayout, + src: Pointer<Tag>, + size: Size, + dest: Pointer<Tag>, + length: u64, + ) -> AllocationRelocations<Tag> { + let relocations = self.get_relocations(cx, src, size); + if relocations.is_empty() { + return AllocationRelocations { relative_relocations: Vec::new() }; + } + + let mut new_relocations = Vec::with_capacity(relocations.len() * (length as usize)); + + for i in 0..length { + new_relocations.extend(relocations.iter().map(|&(offset, reloc)| { + // compute offset for current repetition + let dest_offset = dest.offset + size * i; // `Size` operations + ( + // shift offsets from source allocation to destination allocation + (offset + dest_offset) - src.offset, // `Size` operations + reloc, + ) + })); + } + + AllocationRelocations { relative_relocations: new_relocations } + } + + /// Applies a relocation copy. + /// The affected range, as defined in the parameters to `prepare_relocation_copy` is expected + /// to be clear of relocations. + pub fn mark_relocation_range(&mut self, relocations: AllocationRelocations<Tag>) { + self.relocations.insert_presorted(relocations.relative_relocations); + } +} + +//////////////////////////////////////////////////////////////////////////////// +// Uninitialized byte tracking +//////////////////////////////////////////////////////////////////////////////// + +type Block = u64; + +/// A bitmask where each bit refers to the byte with the same index. If the bit is `true`, the byte +/// is initialized. If it is `false` the byte is uninitialized. +#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub struct InitMask { + blocks: Vec<Block>, + len: Size, +} + +impl InitMask { + pub const BLOCK_SIZE: u64 = 64; + + pub fn new(size: Size, state: bool) -> Self { + let mut m = InitMask { blocks: vec![], len: Size::ZERO }; + m.grow(size, state); + m + } + + /// Checks whether the range `start..end` (end-exclusive) is entirely initialized. + /// + /// Returns `Ok(())` if it's initialized. Otherwise returns a range of byte + /// indexes for the first contiguous span of the uninitialized access. + #[inline] + pub fn is_range_initialized(&self, start: Size, end: Size) -> Result<(), Range<Size>> { + if end > self.len { + return Err(self.len..end); + } + + // FIXME(oli-obk): optimize this for allocations larger than a block. + let idx = (start.bytes()..end.bytes()).map(Size::from_bytes).find(|&i| !self.get(i)); + + match idx { + Some(idx) => { + let uninit_end = (idx.bytes()..end.bytes()) + .map(Size::from_bytes) + .find(|&i| self.get(i)) + .unwrap_or(end); + Err(idx..uninit_end) + } + None => Ok(()), + } + } + + pub fn set_range(&mut self, start: Size, end: Size, new_state: bool) { + let len = self.len; + if end > len { + self.grow(end - len, new_state); + } + self.set_range_inbounds(start, end, new_state); + } + + pub fn set_range_inbounds(&mut self, start: Size, end: Size, new_state: bool) { + let (blocka, bita) = bit_index(start); + let (blockb, bitb) = bit_index(end); + if blocka == blockb { + // First set all bits except the first `bita`, + // then unset the last `64 - bitb` bits. + let range = if bitb == 0 { + u64::MAX << bita + } else { + (u64::MAX << bita) & (u64::MAX >> (64 - bitb)) + }; + if new_state { + self.blocks[blocka] |= range; + } else { + self.blocks[blocka] &= !range; + } + return; + } + // across block boundaries + if new_state { + // Set `bita..64` to `1`. + self.blocks[blocka] |= u64::MAX << bita; + // Set `0..bitb` to `1`. + if bitb != 0 { + self.blocks[blockb] |= u64::MAX >> (64 - bitb); + } + // Fill in all the other blocks (much faster than one bit at a time). + for block in (blocka + 1)..blockb { + self.blocks[block] = u64::MAX; + } + } else { + // Set `bita..64` to `0`. + self.blocks[blocka] &= !(u64::MAX << bita); + // Set `0..bitb` to `0`. + if bitb != 0 { + self.blocks[blockb] &= !(u64::MAX >> (64 - bitb)); + } + // Fill in all the other blocks (much faster than one bit at a time). + for block in (blocka + 1)..blockb { + self.blocks[block] = 0; + } + } + } + + #[inline] + pub fn get(&self, i: Size) -> bool { + let (block, bit) = bit_index(i); + (self.blocks[block] & (1 << bit)) != 0 + } + + #[inline] + pub fn set(&mut self, i: Size, new_state: bool) { + let (block, bit) = bit_index(i); + self.set_bit(block, bit, new_state); + } + + #[inline] + fn set_bit(&mut self, block: usize, bit: usize, new_state: bool) { + if new_state { + self.blocks[block] |= 1 << bit; + } else { + self.blocks[block] &= !(1 << bit); + } + } + + pub fn grow(&mut self, amount: Size, new_state: bool) { + if amount.bytes() == 0 { + return; + } + let unused_trailing_bits = + u64::try_from(self.blocks.len()).unwrap() * Self::BLOCK_SIZE - self.len.bytes(); + if amount.bytes() > unused_trailing_bits { + let additional_blocks = amount.bytes() / Self::BLOCK_SIZE + 1; + self.blocks.extend( + // FIXME(oli-obk): optimize this by repeating `new_state as Block`. + iter::repeat(0).take(usize::try_from(additional_blocks).unwrap()), + ); + } + let start = self.len; + self.len += amount; + self.set_range_inbounds(start, start + amount, new_state); // `Size` operation + } +} + +#[inline] +fn bit_index(bits: Size) -> (usize, usize) { + let bits = bits.bytes(); + let a = bits / InitMask::BLOCK_SIZE; + let b = bits % InitMask::BLOCK_SIZE; + (usize::try_from(a).unwrap(), usize::try_from(b).unwrap()) +} diff --git a/compiler/rustc_middle/src/mir/interpret/error.rs b/compiler/rustc_middle/src/mir/interpret/error.rs new file mode 100644 index 00000000000..059925088ce --- /dev/null +++ b/compiler/rustc_middle/src/mir/interpret/error.rs @@ -0,0 +1,474 @@ +use super::{AllocId, Pointer, RawConst, Scalar}; + +use crate::mir::interpret::ConstValue; +use crate::ty::{layout, query::TyCtxtAt, tls, FnSig, Ty}; + +use rustc_data_structures::sync::Lock; +use rustc_errors::{pluralize, struct_span_err, DiagnosticBuilder, ErrorReported}; +use rustc_macros::HashStable; +use rustc_session::CtfeBacktrace; +use rustc_span::def_id::DefId; +use rustc_target::abi::{Align, Size}; +use std::{any::Any, backtrace::Backtrace, fmt, mem}; + +#[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)] +pub enum ErrorHandled { + /// Already reported an error for this evaluation, and the compilation is + /// *guaranteed* to fail. Warnings/lints *must not* produce `Reported`. + Reported(ErrorReported), + /// Already emitted a lint for this evaluation. + Linted, + /// Don't emit an error, the evaluation failed because the MIR was generic + /// and the substs didn't fully monomorphize it. + TooGeneric, +} + +CloneTypeFoldableAndLiftImpls! { + ErrorHandled, +} + +pub type ConstEvalRawResult<'tcx> = Result<RawConst<'tcx>, ErrorHandled>; +pub type ConstEvalResult<'tcx> = Result<ConstValue<'tcx>, ErrorHandled>; + +pub fn struct_error<'tcx>(tcx: TyCtxtAt<'tcx>, msg: &str) -> DiagnosticBuilder<'tcx> { + struct_span_err!(tcx.sess, tcx.span, E0080, "{}", msg) +} + +/// Packages the kind of error we got from the const code interpreter +/// up with a Rust-level backtrace of where the error occurred. +/// Thsese should always be constructed by calling `.into()` on +/// a `InterpError`. In `librustc_mir::interpret`, we have `throw_err_*` +/// macros for this. +#[derive(Debug)] +pub struct InterpErrorInfo<'tcx> { + pub kind: InterpError<'tcx>, + backtrace: Option<Box<Backtrace>>, +} + +impl fmt::Display for InterpErrorInfo<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "{}", self.kind) + } +} + +impl InterpErrorInfo<'_> { + pub fn print_backtrace(&self) { + if let Some(backtrace) = self.backtrace.as_ref() { + print_backtrace(backtrace); + } + } +} + +fn print_backtrace(backtrace: &Backtrace) { + eprintln!("\n\nAn error occurred in miri:\n{}", backtrace); +} + +impl From<ErrorHandled> for InterpErrorInfo<'_> { + fn from(err: ErrorHandled) -> Self { + match err { + ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => { + err_inval!(ReferencedConstant) + } + ErrorHandled::TooGeneric => err_inval!(TooGeneric), + } + .into() + } +} + +impl<'tcx> From<InterpError<'tcx>> for InterpErrorInfo<'tcx> { + fn from(kind: InterpError<'tcx>) -> Self { + let capture_backtrace = tls::with_opt(|tcx| { + if let Some(tcx) = tcx { + *Lock::borrow(&tcx.sess.ctfe_backtrace) + } else { + CtfeBacktrace::Disabled + } + }); + + let backtrace = match capture_backtrace { + CtfeBacktrace::Disabled => None, + CtfeBacktrace::Capture => Some(Box::new(Backtrace::force_capture())), + CtfeBacktrace::Immediate => { + // Print it now. + let backtrace = Backtrace::force_capture(); + print_backtrace(&backtrace); + None + } + }; + + InterpErrorInfo { kind, backtrace } + } +} + +/// Error information for when the program we executed turned out not to actually be a valid +/// program. This cannot happen in stand-alone Miri, but it can happen during CTFE/ConstProp +/// where we work on generic code or execution does not have all information available. +pub enum InvalidProgramInfo<'tcx> { + /// Resolution can fail if we are in a too generic context. + TooGeneric, + /// Cannot compute this constant because it depends on another one + /// which already produced an error. + ReferencedConstant, + /// Abort in case type errors are reached. + TypeckError(ErrorReported), + /// An error occurred during layout computation. + Layout(layout::LayoutError<'tcx>), + /// An invalid transmute happened. + TransmuteSizeDiff(Ty<'tcx>, Ty<'tcx>), +} + +impl fmt::Display for InvalidProgramInfo<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use InvalidProgramInfo::*; + match self { + TooGeneric => write!(f, "encountered overly generic constant"), + ReferencedConstant => write!(f, "referenced constant has errors"), + TypeckError(ErrorReported) => { + write!(f, "encountered constants with type errors, stopping evaluation") + } + Layout(ref err) => write!(f, "{}", err), + TransmuteSizeDiff(from_ty, to_ty) => write!( + f, + "transmuting `{}` to `{}` is not possible, because these types do not have the same size", + from_ty, to_ty + ), + } + } +} + +/// Details of why a pointer had to be in-bounds. +#[derive(Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)] +pub enum CheckInAllocMsg { + MemoryAccessTest, + NullPointerTest, + PointerArithmeticTest, + InboundsTest, +} + +impl fmt::Display for CheckInAllocMsg { + /// When this is printed as an error the context looks like this + /// "{test name} failed: pointer must be in-bounds at offset..." + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "{}", + match *self { + CheckInAllocMsg::MemoryAccessTest => "memory access", + CheckInAllocMsg::NullPointerTest => "NULL pointer test", + CheckInAllocMsg::PointerArithmeticTest => "pointer arithmetic", + CheckInAllocMsg::InboundsTest => "inbounds test", + } + ) + } +} + +/// Details of an access to uninitialized bytes where it is not allowed. +#[derive(Debug)] +pub struct UninitBytesAccess { + /// Location of the original memory access. + pub access_ptr: Pointer, + /// Size of the original memory access. + pub access_size: Size, + /// Location of the first uninitialized byte that was accessed. + pub uninit_ptr: Pointer, + /// Number of consecutive uninitialized bytes that were accessed. + pub uninit_size: Size, +} + +/// Error information for when the program caused Undefined Behavior. +pub enum UndefinedBehaviorInfo<'tcx> { + /// Free-form case. Only for errors that are never caught! + Ub(String), + /// Unreachable code was executed. + Unreachable, + /// A slice/array index projection went out-of-bounds. + BoundsCheckFailed { + len: u64, + index: u64, + }, + /// Something was divided by 0 (x / 0). + DivisionByZero, + /// Something was "remainded" by 0 (x % 0). + RemainderByZero, + /// Overflowing inbounds pointer arithmetic. + PointerArithOverflow, + /// Invalid metadata in a wide pointer (using `str` to avoid allocations). + InvalidMeta(&'static str), + /// Invalid drop function in vtable. + InvalidDropFn(FnSig<'tcx>), + /// Reading a C string that does not end within its allocation. + UnterminatedCString(Pointer), + /// Dereferencing a dangling pointer after it got freed. + PointerUseAfterFree(AllocId), + /// Used a pointer outside the bounds it is valid for. + PointerOutOfBounds { + ptr: Pointer, + msg: CheckInAllocMsg, + allocation_size: Size, + }, + /// Using an integer as a pointer in the wrong way. + DanglingIntPointer(u64, CheckInAllocMsg), + /// Used a pointer with bad alignment. + AlignmentCheckFailed { + required: Align, + has: Align, + }, + /// Writing to read-only memory. + WriteToReadOnly(AllocId), + // Trying to access the data behind a function pointer. + DerefFunctionPointer(AllocId), + /// The value validity check found a problem. + /// Should only be thrown by `validity.rs` and always point out which part of the value + /// is the problem. + ValidationFailure(String), + /// Using a non-boolean `u8` as bool. + InvalidBool(u8), + /// Using a non-character `u32` as character. + InvalidChar(u32), + /// The tag of an enum does not encode an actual discriminant. + InvalidTag(Scalar), + /// Using a pointer-not-to-a-function as function pointer. + InvalidFunctionPointer(Pointer), + /// Using a string that is not valid UTF-8, + InvalidStr(std::str::Utf8Error), + /// Using uninitialized data where it is not allowed. + InvalidUninitBytes(Option<Box<UninitBytesAccess>>), + /// Working with a local that is not currently live. + DeadLocal, + /// Data size is not equal to target size. + ScalarSizeMismatch { + target_size: u64, + data_size: u64, + }, +} + +impl fmt::Display for UndefinedBehaviorInfo<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use UndefinedBehaviorInfo::*; + match self { + Ub(msg) => write!(f, "{}", msg), + Unreachable => write!(f, "entering unreachable code"), + BoundsCheckFailed { ref len, ref index } => { + write!(f, "indexing out of bounds: the len is {} but the index is {}", len, index) + } + DivisionByZero => write!(f, "dividing by zero"), + RemainderByZero => write!(f, "calculating the remainder with a divisor of zero"), + PointerArithOverflow => write!(f, "overflowing in-bounds pointer arithmetic"), + InvalidMeta(msg) => write!(f, "invalid metadata in wide pointer: {}", msg), + InvalidDropFn(sig) => write!( + f, + "invalid drop function signature: got {}, expected exactly one argument which must be a pointer type", + sig + ), + UnterminatedCString(p) => write!( + f, + "reading a null-terminated string starting at {} with no null found before end of allocation", + p, + ), + PointerUseAfterFree(a) => { + write!(f, "pointer to {} was dereferenced after this allocation got freed", a) + } + PointerOutOfBounds { ptr, msg, allocation_size } => write!( + f, + "{} failed: pointer must be in-bounds at offset {}, \ + but is outside bounds of {} which has size {}", + msg, + ptr.offset.bytes(), + ptr.alloc_id, + allocation_size.bytes() + ), + DanglingIntPointer(_, CheckInAllocMsg::NullPointerTest) => { + write!(f, "NULL pointer is not allowed for this operation") + } + DanglingIntPointer(i, msg) => { + write!(f, "{} failed: 0x{:x} is not a valid pointer", msg, i) + } + AlignmentCheckFailed { required, has } => write!( + f, + "accessing memory with alignment {}, but alignment {} is required", + has.bytes(), + required.bytes() + ), + WriteToReadOnly(a) => write!(f, "writing to {} which is read-only", a), + DerefFunctionPointer(a) => write!(f, "accessing {} which contains a function", a), + ValidationFailure(ref err) => write!(f, "type validation failed: {}", err), + InvalidBool(b) => { + write!(f, "interpreting an invalid 8-bit value as a bool: 0x{:02x}", b) + } + InvalidChar(c) => { + write!(f, "interpreting an invalid 32-bit value as a char: 0x{:08x}", c) + } + InvalidTag(val) => write!(f, "enum value has invalid tag: {}", val), + InvalidFunctionPointer(p) => { + write!(f, "using {} as function pointer but it does not point to a function", p) + } + InvalidStr(err) => write!(f, "this string is not valid UTF-8: {}", err), + InvalidUninitBytes(Some(access)) => write!( + f, + "reading {} byte{} of memory starting at {}, \ + but {} byte{} {} uninitialized starting at {}, \ + and this operation requires initialized memory", + access.access_size.bytes(), + pluralize!(access.access_size.bytes()), + access.access_ptr, + access.uninit_size.bytes(), + pluralize!(access.uninit_size.bytes()), + if access.uninit_size.bytes() != 1 { "are" } else { "is" }, + access.uninit_ptr, + ), + InvalidUninitBytes(None) => write!( + f, + "using uninitialized data, but this operation requires initialized memory" + ), + DeadLocal => write!(f, "accessing a dead local variable"), + ScalarSizeMismatch { target_size, data_size } => write!( + f, + "scalar size mismatch: expected {} bytes but got {} bytes instead", + target_size, data_size + ), + } + } +} + +/// Error information for when the program did something that might (or might not) be correct +/// to do according to the Rust spec, but due to limitations in the interpreter, the +/// operation could not be carried out. These limitations can differ between CTFE and the +/// Miri engine, e.g., CTFE does not support dereferencing pointers at integral addresses. +pub enum UnsupportedOpInfo { + /// Free-form case. Only for errors that are never caught! + Unsupported(String), + /// Could not find MIR for a function. + NoMirFor(DefId), + /// Encountered a pointer where we needed raw bytes. + ReadPointerAsBytes, + // + // The variants below are only reachable from CTFE/const prop, miri will never emit them. + // + /// Encountered raw bytes where we needed a pointer. + ReadBytesAsPointer, + /// Accessing thread local statics + ThreadLocalStatic(DefId), + /// Accessing an unsupported extern static. + ReadExternStatic(DefId), +} + +impl fmt::Display for UnsupportedOpInfo { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use UnsupportedOpInfo::*; + match self { + Unsupported(ref msg) => write!(f, "{}", msg), + ReadExternStatic(did) => write!(f, "cannot read from extern static ({:?})", did), + NoMirFor(did) => write!(f, "no MIR body is available for {:?}", did), + ReadPointerAsBytes => write!(f, "unable to turn pointer into raw bytes",), + ReadBytesAsPointer => write!(f, "unable to turn bytes into a pointer"), + ThreadLocalStatic(did) => write!(f, "cannot access thread local static ({:?})", did), + } + } +} + +/// Error information for when the program exhausted the resources granted to it +/// by the interpreter. +pub enum ResourceExhaustionInfo { + /// The stack grew too big. + StackFrameLimitReached, + /// The program ran for too long. + /// + /// The exact limit is set by the `const_eval_limit` attribute. + StepLimitReached, +} + +impl fmt::Display for ResourceExhaustionInfo { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use ResourceExhaustionInfo::*; + match self { + StackFrameLimitReached => { + write!(f, "reached the configured maximum number of stack frames") + } + StepLimitReached => { + write!(f, "exceeded interpreter step limit (see `#[const_eval_limit]`)") + } + } + } +} + +/// A trait to work around not having trait object upcasting. +pub trait AsAny: Any { + fn as_any(&self) -> &dyn Any; +} +impl<T: Any> AsAny for T { + #[inline(always)] + fn as_any(&self) -> &dyn Any { + self + } +} + +/// A trait for machine-specific errors (or other "machine stop" conditions). +pub trait MachineStopType: AsAny + fmt::Display + Send {} +impl MachineStopType for String {} + +impl dyn MachineStopType { + #[inline(always)] + pub fn downcast_ref<T: Any>(&self) -> Option<&T> { + self.as_any().downcast_ref() + } +} + +#[cfg(target_arch = "x86_64")] +static_assert_size!(InterpError<'_>, 40); + +pub enum InterpError<'tcx> { + /// The program caused undefined behavior. + UndefinedBehavior(UndefinedBehaviorInfo<'tcx>), + /// The program did something the interpreter does not support (some of these *might* be UB + /// but the interpreter is not sure). + Unsupported(UnsupportedOpInfo), + /// The program was invalid (ill-typed, bad MIR, not sufficiently monomorphized, ...). + InvalidProgram(InvalidProgramInfo<'tcx>), + /// The program exhausted the interpreter's resources (stack/heap too big, + /// execution takes too long, ...). + ResourceExhaustion(ResourceExhaustionInfo), + /// Stop execution for a machine-controlled reason. This is never raised by + /// the core engine itself. + MachineStop(Box<dyn MachineStopType>), +} + +pub type InterpResult<'tcx, T = ()> = Result<T, InterpErrorInfo<'tcx>>; + +impl fmt::Display for InterpError<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use InterpError::*; + match *self { + Unsupported(ref msg) => write!(f, "{}", msg), + InvalidProgram(ref msg) => write!(f, "{}", msg), + UndefinedBehavior(ref msg) => write!(f, "{}", msg), + ResourceExhaustion(ref msg) => write!(f, "{}", msg), + MachineStop(ref msg) => write!(f, "{}", msg), + } + } +} + +// Forward `Debug` to `Display`, so it does not look awful. +impl fmt::Debug for InterpError<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(self, f) + } +} + +impl InterpError<'_> { + /// Some errors allocate to be created as they contain free-form strings. + /// And sometimes we want to be sure that did not happen as it is a + /// waste of resources. + pub fn allocates(&self) -> bool { + match self { + // Zero-sized boxes do not allocate. + InterpError::MachineStop(b) => mem::size_of_val::<dyn MachineStopType>(&**b) > 0, + InterpError::Unsupported(UnsupportedOpInfo::Unsupported(_)) + | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::ValidationFailure(_)) + | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::Ub(_)) + | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::InvalidUninitBytes(Some(_))) => { + true + } + _ => false, + } + } +} diff --git a/compiler/rustc_middle/src/mir/interpret/mod.rs b/compiler/rustc_middle/src/mir/interpret/mod.rs new file mode 100644 index 00000000000..0dc3d6e344a --- /dev/null +++ b/compiler/rustc_middle/src/mir/interpret/mod.rs @@ -0,0 +1,618 @@ +//! An interpreter for MIR used in CTFE and by miri. + +#[macro_export] +macro_rules! err_unsup { + ($($tt:tt)*) => { + $crate::mir::interpret::InterpError::Unsupported( + $crate::mir::interpret::UnsupportedOpInfo::$($tt)* + ) + }; +} + +#[macro_export] +macro_rules! err_unsup_format { + ($($tt:tt)*) => { err_unsup!(Unsupported(format!($($tt)*))) }; +} + +#[macro_export] +macro_rules! err_inval { + ($($tt:tt)*) => { + $crate::mir::interpret::InterpError::InvalidProgram( + $crate::mir::interpret::InvalidProgramInfo::$($tt)* + ) + }; +} + +#[macro_export] +macro_rules! err_ub { + ($($tt:tt)*) => { + $crate::mir::interpret::InterpError::UndefinedBehavior( + $crate::mir::interpret::UndefinedBehaviorInfo::$($tt)* + ) + }; +} + +#[macro_export] +macro_rules! err_ub_format { + ($($tt:tt)*) => { err_ub!(Ub(format!($($tt)*))) }; +} + +#[macro_export] +macro_rules! err_exhaust { + ($($tt:tt)*) => { + $crate::mir::interpret::InterpError::ResourceExhaustion( + $crate::mir::interpret::ResourceExhaustionInfo::$($tt)* + ) + }; +} + +#[macro_export] +macro_rules! err_machine_stop { + ($($tt:tt)*) => { + $crate::mir::interpret::InterpError::MachineStop(Box::new($($tt)*)) + }; +} + +// In the `throw_*` macros, avoid `return` to make them work with `try {}`. +#[macro_export] +macro_rules! throw_unsup { + ($($tt:tt)*) => { Err::<!, _>(err_unsup!($($tt)*))? }; +} + +#[macro_export] +macro_rules! throw_unsup_format { + ($($tt:tt)*) => { throw_unsup!(Unsupported(format!($($tt)*))) }; +} + +#[macro_export] +macro_rules! throw_inval { + ($($tt:tt)*) => { Err::<!, _>(err_inval!($($tt)*))? }; +} + +#[macro_export] +macro_rules! throw_ub { + ($($tt:tt)*) => { Err::<!, _>(err_ub!($($tt)*))? }; +} + +#[macro_export] +macro_rules! throw_ub_format { + ($($tt:tt)*) => { throw_ub!(Ub(format!($($tt)*))) }; +} + +#[macro_export] +macro_rules! throw_exhaust { + ($($tt:tt)*) => { Err::<!, _>(err_exhaust!($($tt)*))? }; +} + +#[macro_export] +macro_rules! throw_machine_stop { + ($($tt:tt)*) => { Err::<!, _>(err_machine_stop!($($tt)*))? }; +} + +mod allocation; +mod error; +mod pointer; +mod queries; +mod value; + +use std::convert::TryFrom; +use std::fmt; +use std::io; +use std::num::NonZeroU32; +use std::sync::atomic::{AtomicU32, Ordering}; + +use byteorder::{BigEndian, LittleEndian, ReadBytesExt, WriteBytesExt}; +use rustc_ast::LitKind; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::sync::{HashMapExt, Lock}; +use rustc_data_structures::tiny_list::TinyList; +use rustc_hir::def_id::DefId; +use rustc_macros::HashStable; +use rustc_serialize::{Decodable, Encodable}; +use rustc_target::abi::{Endian, Size}; + +use crate::mir; +use crate::ty::codec::{TyDecoder, TyEncoder}; +use crate::ty::subst::GenericArgKind; +use crate::ty::{self, Instance, Ty, TyCtxt}; + +pub use self::error::{ + struct_error, CheckInAllocMsg, ConstEvalRawResult, ConstEvalResult, ErrorHandled, InterpError, + InterpErrorInfo, InterpResult, InvalidProgramInfo, MachineStopType, ResourceExhaustionInfo, + UndefinedBehaviorInfo, UninitBytesAccess, UnsupportedOpInfo, +}; + +pub use self::value::{get_slice_bytes, ConstValue, RawConst, Scalar, ScalarMaybeUninit}; + +pub use self::allocation::{Allocation, AllocationExtra, InitMask, Relocations}; + +pub use self::pointer::{Pointer, PointerArithmetic}; + +/// Uniquely identifies one of the following: +/// - A constant +/// - A static +/// - A const fn where all arguments (if any) are zero-sized types +#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, Lift)] +pub struct GlobalId<'tcx> { + /// For a constant or static, the `Instance` of the item itself. + /// For a promoted global, the `Instance` of the function they belong to. + pub instance: ty::Instance<'tcx>, + + /// The index for promoted globals within their function's `mir::Body`. + pub promoted: Option<mir::Promoted>, +} + +impl GlobalId<'tcx> { + pub fn display(self, tcx: TyCtxt<'tcx>) -> String { + let instance_name = tcx.def_path_str(self.instance.def.def_id()); + if let Some(promoted) = self.promoted { + format!("{}::{:?}", instance_name, promoted) + } else { + instance_name + } + } +} + +/// Input argument for `tcx.lit_to_const`. +#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, HashStable)] +pub struct LitToConstInput<'tcx> { + /// The absolute value of the resultant constant. + pub lit: &'tcx LitKind, + /// The type of the constant. + pub ty: Ty<'tcx>, + /// If the constant is negative. + pub neg: bool, +} + +/// Error type for `tcx.lit_to_const`. +#[derive(Copy, Clone, Debug, Eq, PartialEq, HashStable)] +pub enum LitToConstError { + /// The literal's inferred type did not match the expected `ty` in the input. + /// This is used for graceful error handling (`delay_span_bug`) in + /// type checking (`Const::from_anon_const`). + TypeError, + UnparseableFloat, + Reported, +} + +#[derive(Copy, Clone, Eq, Hash, Ord, PartialEq, PartialOrd)] +pub struct AllocId(pub u64); + +// We want the `Debug` output to be readable as it is used by `derive(Debug)` for +// all the Miri types. +impl fmt::Debug for AllocId { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + if f.alternate() { write!(f, "a{}", self.0) } else { write!(f, "alloc{}", self.0) } + } +} + +impl fmt::Display for AllocId { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(self, f) + } +} + +#[derive(TyDecodable, TyEncodable)] +enum AllocDiscriminant { + Alloc, + Fn, + Static, +} + +pub fn specialized_encode_alloc_id<'tcx, E: TyEncoder<'tcx>>( + encoder: &mut E, + tcx: TyCtxt<'tcx>, + alloc_id: AllocId, +) -> Result<(), E::Error> { + match tcx.global_alloc(alloc_id) { + GlobalAlloc::Memory(alloc) => { + trace!("encoding {:?} with {:#?}", alloc_id, alloc); + AllocDiscriminant::Alloc.encode(encoder)?; + alloc.encode(encoder)?; + } + GlobalAlloc::Function(fn_instance) => { + trace!("encoding {:?} with {:#?}", alloc_id, fn_instance); + AllocDiscriminant::Fn.encode(encoder)?; + fn_instance.encode(encoder)?; + } + GlobalAlloc::Static(did) => { + assert!(!tcx.is_thread_local_static(did)); + // References to statics doesn't need to know about their allocations, + // just about its `DefId`. + AllocDiscriminant::Static.encode(encoder)?; + did.encode(encoder)?; + } + } + Ok(()) +} + +// Used to avoid infinite recursion when decoding cyclic allocations. +type DecodingSessionId = NonZeroU32; + +#[derive(Clone)] +enum State { + Empty, + InProgressNonAlloc(TinyList<DecodingSessionId>), + InProgress(TinyList<DecodingSessionId>, AllocId), + Done(AllocId), +} + +pub struct AllocDecodingState { + // For each `AllocId`, we keep track of which decoding state it's currently in. + decoding_state: Vec<Lock<State>>, + // The offsets of each allocation in the data stream. + data_offsets: Vec<u32>, +} + +impl AllocDecodingState { + pub fn new_decoding_session(&self) -> AllocDecodingSession<'_> { + static DECODER_SESSION_ID: AtomicU32 = AtomicU32::new(0); + let counter = DECODER_SESSION_ID.fetch_add(1, Ordering::SeqCst); + + // Make sure this is never zero. + let session_id = DecodingSessionId::new((counter & 0x7FFFFFFF) + 1).unwrap(); + + AllocDecodingSession { state: self, session_id } + } + + pub fn new(data_offsets: Vec<u32>) -> Self { + let decoding_state = vec![Lock::new(State::Empty); data_offsets.len()]; + + Self { decoding_state, data_offsets } + } +} + +#[derive(Copy, Clone)] +pub struct AllocDecodingSession<'s> { + state: &'s AllocDecodingState, + session_id: DecodingSessionId, +} + +impl<'s> AllocDecodingSession<'s> { + /// Decodes an `AllocId` in a thread-safe way. + pub fn decode_alloc_id<D>(&self, decoder: &mut D) -> Result<AllocId, D::Error> + where + D: TyDecoder<'tcx>, + { + // Read the index of the allocation. + let idx = usize::try_from(decoder.read_u32()?).unwrap(); + let pos = usize::try_from(self.state.data_offsets[idx]).unwrap(); + + // Decode the `AllocDiscriminant` now so that we know if we have to reserve an + // `AllocId`. + let (alloc_kind, pos) = decoder.with_position(pos, |decoder| { + let alloc_kind = AllocDiscriminant::decode(decoder)?; + Ok((alloc_kind, decoder.position())) + })?; + + // Check the decoding state to see if it's already decoded or if we should + // decode it here. + let alloc_id = { + let mut entry = self.state.decoding_state[idx].lock(); + + match *entry { + State::Done(alloc_id) => { + return Ok(alloc_id); + } + ref mut entry @ State::Empty => { + // We are allowed to decode. + match alloc_kind { + AllocDiscriminant::Alloc => { + // If this is an allocation, we need to reserve an + // `AllocId` so we can decode cyclic graphs. + let alloc_id = decoder.tcx().reserve_alloc_id(); + *entry = + State::InProgress(TinyList::new_single(self.session_id), alloc_id); + Some(alloc_id) + } + AllocDiscriminant::Fn | AllocDiscriminant::Static => { + // Fns and statics cannot be cyclic, and their `AllocId` + // is determined later by interning. + *entry = + State::InProgressNonAlloc(TinyList::new_single(self.session_id)); + None + } + } + } + State::InProgressNonAlloc(ref mut sessions) => { + if sessions.contains(&self.session_id) { + bug!("this should be unreachable"); + } else { + // Start decoding concurrently. + sessions.insert(self.session_id); + None + } + } + State::InProgress(ref mut sessions, alloc_id) => { + if sessions.contains(&self.session_id) { + // Don't recurse. + return Ok(alloc_id); + } else { + // Start decoding concurrently. + sessions.insert(self.session_id); + Some(alloc_id) + } + } + } + }; + + // Now decode the actual data. + let alloc_id = decoder.with_position(pos, |decoder| { + match alloc_kind { + AllocDiscriminant::Alloc => { + let alloc = <&'tcx Allocation as Decodable<_>>::decode(decoder)?; + // We already have a reserved `AllocId`. + let alloc_id = alloc_id.unwrap(); + trace!("decoded alloc {:?}: {:#?}", alloc_id, alloc); + decoder.tcx().set_alloc_id_same_memory(alloc_id, alloc); + Ok(alloc_id) + } + AllocDiscriminant::Fn => { + assert!(alloc_id.is_none()); + trace!("creating fn alloc ID"); + let instance = ty::Instance::decode(decoder)?; + trace!("decoded fn alloc instance: {:?}", instance); + let alloc_id = decoder.tcx().create_fn_alloc(instance); + Ok(alloc_id) + } + AllocDiscriminant::Static => { + assert!(alloc_id.is_none()); + trace!("creating extern static alloc ID"); + let did = <DefId as Decodable<D>>::decode(decoder)?; + trace!("decoded static def-ID: {:?}", did); + let alloc_id = decoder.tcx().create_static_alloc(did); + Ok(alloc_id) + } + } + })?; + + self.state.decoding_state[idx].with_lock(|entry| { + *entry = State::Done(alloc_id); + }); + + Ok(alloc_id) + } +} + +/// An allocation in the global (tcx-managed) memory can be either a function pointer, +/// a static, or a "real" allocation with some data in it. +#[derive(Debug, Clone, Eq, PartialEq, Hash, TyDecodable, TyEncodable, HashStable)] +pub enum GlobalAlloc<'tcx> { + /// The alloc ID is used as a function pointer. + Function(Instance<'tcx>), + /// The alloc ID points to a "lazy" static variable that did not get computed (yet). + /// This is also used to break the cycle in recursive statics. + Static(DefId), + /// The alloc ID points to memory. + Memory(&'tcx Allocation), +} + +impl GlobalAlloc<'tcx> { + /// Panics if the `GlobalAlloc` does not refer to an `GlobalAlloc::Memory` + #[track_caller] + #[inline] + pub fn unwrap_memory(&self) -> &'tcx Allocation { + match *self { + GlobalAlloc::Memory(mem) => mem, + _ => bug!("expected memory, got {:?}", self), + } + } + + /// Panics if the `GlobalAlloc` is not `GlobalAlloc::Function` + #[track_caller] + #[inline] + pub fn unwrap_fn(&self) -> Instance<'tcx> { + match *self { + GlobalAlloc::Function(instance) => instance, + _ => bug!("expected function, got {:?}", self), + } + } +} + +crate struct AllocMap<'tcx> { + /// Maps `AllocId`s to their corresponding allocations. + alloc_map: FxHashMap<AllocId, GlobalAlloc<'tcx>>, + + /// Used to ensure that statics and functions only get one associated `AllocId`. + /// Should never contain a `GlobalAlloc::Memory`! + // + // FIXME: Should we just have two separate dedup maps for statics and functions each? + dedup: FxHashMap<GlobalAlloc<'tcx>, AllocId>, + + /// The `AllocId` to assign to the next requested ID. + /// Always incremented; never gets smaller. + next_id: AllocId, +} + +impl<'tcx> AllocMap<'tcx> { + crate fn new() -> Self { + AllocMap { alloc_map: Default::default(), dedup: Default::default(), next_id: AllocId(0) } + } + fn reserve(&mut self) -> AllocId { + let next = self.next_id; + self.next_id.0 = self.next_id.0.checked_add(1).expect( + "You overflowed a u64 by incrementing by 1... \ + You've just earned yourself a free drink if we ever meet. \ + Seriously, how did you do that?!", + ); + next + } +} + +impl<'tcx> TyCtxt<'tcx> { + /// Obtains a new allocation ID that can be referenced but does not + /// yet have an allocation backing it. + /// + /// Make sure to call `set_alloc_id_memory` or `set_alloc_id_same_memory` before returning such + /// an `AllocId` from a query. + pub fn reserve_alloc_id(&self) -> AllocId { + self.alloc_map.lock().reserve() + } + + /// Reserves a new ID *if* this allocation has not been dedup-reserved before. + /// Should only be used for function pointers and statics, we don't want + /// to dedup IDs for "real" memory! + fn reserve_and_set_dedup(&self, alloc: GlobalAlloc<'tcx>) -> AllocId { + let mut alloc_map = self.alloc_map.lock(); + match alloc { + GlobalAlloc::Function(..) | GlobalAlloc::Static(..) => {} + GlobalAlloc::Memory(..) => bug!("Trying to dedup-reserve memory with real data!"), + } + if let Some(&alloc_id) = alloc_map.dedup.get(&alloc) { + return alloc_id; + } + let id = alloc_map.reserve(); + debug!("creating alloc {:?} with id {}", alloc, id); + alloc_map.alloc_map.insert(id, alloc.clone()); + alloc_map.dedup.insert(alloc, id); + id + } + + /// Generates an `AllocId` for a static or return a cached one in case this function has been + /// called on the same static before. + pub fn create_static_alloc(&self, static_id: DefId) -> AllocId { + self.reserve_and_set_dedup(GlobalAlloc::Static(static_id)) + } + + /// Generates an `AllocId` for a function. Depending on the function type, + /// this might get deduplicated or assigned a new ID each time. + pub fn create_fn_alloc(&self, instance: Instance<'tcx>) -> AllocId { + // Functions cannot be identified by pointers, as asm-equal functions can get deduplicated + // by the linker (we set the "unnamed_addr" attribute for LLVM) and functions can be + // duplicated across crates. + // We thus generate a new `AllocId` for every mention of a function. This means that + // `main as fn() == main as fn()` is false, while `let x = main as fn(); x == x` is true. + // However, formatting code relies on function identity (see #58320), so we only do + // this for generic functions. Lifetime parameters are ignored. + let is_generic = instance.substs.into_iter().any(|kind| match kind.unpack() { + GenericArgKind::Lifetime(_) => false, + _ => true, + }); + if is_generic { + // Get a fresh ID. + let mut alloc_map = self.alloc_map.lock(); + let id = alloc_map.reserve(); + alloc_map.alloc_map.insert(id, GlobalAlloc::Function(instance)); + id + } else { + // Deduplicate. + self.reserve_and_set_dedup(GlobalAlloc::Function(instance)) + } + } + + /// Interns the `Allocation` and return a new `AllocId`, even if there's already an identical + /// `Allocation` with a different `AllocId`. + /// Statics with identical content will still point to the same `Allocation`, i.e., + /// their data will be deduplicated through `Allocation` interning -- but they + /// are different places in memory and as such need different IDs. + pub fn create_memory_alloc(&self, mem: &'tcx Allocation) -> AllocId { + let id = self.reserve_alloc_id(); + self.set_alloc_id_memory(id, mem); + id + } + + /// Returns `None` in case the `AllocId` is dangling. An `InterpretCx` can still have a + /// local `Allocation` for that `AllocId`, but having such an `AllocId` in a constant is + /// illegal and will likely ICE. + /// This function exists to allow const eval to detect the difference between evaluation- + /// local dangling pointers and allocations in constants/statics. + #[inline] + pub fn get_global_alloc(&self, id: AllocId) -> Option<GlobalAlloc<'tcx>> { + self.alloc_map.lock().alloc_map.get(&id).cloned() + } + + #[inline] + #[track_caller] + /// Panics in case the `AllocId` is dangling. Since that is impossible for `AllocId`s in + /// constants (as all constants must pass interning and validation that check for dangling + /// ids), this function is frequently used throughout rustc, but should not be used within + /// the miri engine. + pub fn global_alloc(&self, id: AllocId) -> GlobalAlloc<'tcx> { + match self.get_global_alloc(id) { + Some(alloc) => alloc, + None => bug!("could not find allocation for {}", id), + } + } + + /// Freezes an `AllocId` created with `reserve` by pointing it at an `Allocation`. Trying to + /// call this function twice, even with the same `Allocation` will ICE the compiler. + pub fn set_alloc_id_memory(&self, id: AllocId, mem: &'tcx Allocation) { + if let Some(old) = self.alloc_map.lock().alloc_map.insert(id, GlobalAlloc::Memory(mem)) { + bug!("tried to set allocation ID {}, but it was already existing as {:#?}", id, old); + } + } + + /// Freezes an `AllocId` created with `reserve` by pointing it at an `Allocation`. May be called + /// twice for the same `(AllocId, Allocation)` pair. + fn set_alloc_id_same_memory(&self, id: AllocId, mem: &'tcx Allocation) { + self.alloc_map.lock().alloc_map.insert_same(id, GlobalAlloc::Memory(mem)); + } +} + +//////////////////////////////////////////////////////////////////////////////// +// Methods to access integers in the target endianness +//////////////////////////////////////////////////////////////////////////////// + +#[inline] +pub fn write_target_uint( + endianness: Endian, + mut target: &mut [u8], + data: u128, +) -> Result<(), io::Error> { + let len = target.len(); + match endianness { + Endian::Little => target.write_uint128::<LittleEndian>(data, len), + Endian::Big => target.write_uint128::<BigEndian>(data, len), + } +} + +#[inline] +pub fn read_target_uint(endianness: Endian, mut source: &[u8]) -> Result<u128, io::Error> { + match endianness { + Endian::Little => source.read_uint128::<LittleEndian>(source.len()), + Endian::Big => source.read_uint128::<BigEndian>(source.len()), + } +} + +//////////////////////////////////////////////////////////////////////////////// +// Methods to facilitate working with signed integers stored in a u128 +//////////////////////////////////////////////////////////////////////////////// + +/// Truncates `value` to `size` bits and then sign-extend it to 128 bits +/// (i.e., if it is negative, fill with 1's on the left). +#[inline] +pub fn sign_extend(value: u128, size: Size) -> u128 { + let size = size.bits(); + if size == 0 { + // Truncated until nothing is left. + return 0; + } + // Sign-extend it. + let shift = 128 - size; + // Shift the unsigned value to the left, then shift back to the right as signed + // (essentially fills with FF on the left). + (((value << shift) as i128) >> shift) as u128 +} + +/// Truncates `value` to `size` bits. +#[inline] +pub fn truncate(value: u128, size: Size) -> u128 { + let size = size.bits(); + if size == 0 { + // Truncated until nothing is left. + return 0; + } + let shift = 128 - size; + // Truncate (shift left to drop out leftover values, shift right to fill with zeroes). + (value << shift) >> shift +} + +/// Computes the unsigned absolute value without wrapping or panicking. +#[inline] +pub fn uabs(value: i64) -> u64 { + // The only tricky part here is if value == i64::MIN. In that case, + // wrapping_abs() returns i64::MIN == -2^63. Casting this value to a u64 + // gives 2^63, the correct value. + value.wrapping_abs() as u64 +} diff --git a/compiler/rustc_middle/src/mir/interpret/pointer.rs b/compiler/rustc_middle/src/mir/interpret/pointer.rs new file mode 100644 index 00000000000..e3d5a085613 --- /dev/null +++ b/compiler/rustc_middle/src/mir/interpret/pointer.rs @@ -0,0 +1,208 @@ +use super::{uabs, AllocId, InterpResult}; + +use rustc_macros::HashStable; +use rustc_target::abi::{HasDataLayout, Size}; + +use std::convert::TryFrom; +use std::fmt; + +//////////////////////////////////////////////////////////////////////////////// +// Pointer arithmetic +//////////////////////////////////////////////////////////////////////////////// + +pub trait PointerArithmetic: HasDataLayout { + // These are not supposed to be overridden. + + #[inline(always)] + fn pointer_size(&self) -> Size { + self.data_layout().pointer_size + } + + #[inline] + fn machine_usize_max(&self) -> u64 { + let max_usize_plus_1 = 1u128 << self.pointer_size().bits(); + u64::try_from(max_usize_plus_1 - 1).unwrap() + } + + #[inline] + fn machine_isize_min(&self) -> i64 { + let max_isize_plus_1 = 1i128 << (self.pointer_size().bits() - 1); + i64::try_from(-max_isize_plus_1).unwrap() + } + + #[inline] + fn machine_isize_max(&self) -> i64 { + let max_isize_plus_1 = 1u128 << (self.pointer_size().bits() - 1); + i64::try_from(max_isize_plus_1 - 1).unwrap() + } + + /// Helper function: truncate given value-"overflowed flag" pair to pointer size and + /// update "overflowed flag" if there was an overflow. + /// This should be called by all the other methods before returning! + #[inline] + fn truncate_to_ptr(&self, (val, over): (u64, bool)) -> (u64, bool) { + let val = u128::from(val); + let max_ptr_plus_1 = 1u128 << self.pointer_size().bits(); + (u64::try_from(val % max_ptr_plus_1).unwrap(), over || val >= max_ptr_plus_1) + } + + #[inline] + fn overflowing_offset(&self, val: u64, i: u64) -> (u64, bool) { + // We do not need to check if i fits in a machine usize. If it doesn't, + // either the wrapping_add will wrap or res will not fit in a pointer. + let res = val.overflowing_add(i); + self.truncate_to_ptr(res) + } + + #[inline] + fn overflowing_signed_offset(&self, val: u64, i: i64) -> (u64, bool) { + // We need to make sure that i fits in a machine isize. + let n = uabs(i); + if i >= 0 { + let (val, over) = self.overflowing_offset(val, n); + (val, over || i > self.machine_isize_max()) + } else { + let res = val.overflowing_sub(n); + let (val, over) = self.truncate_to_ptr(res); + (val, over || i < self.machine_isize_min()) + } + } + + #[inline] + fn offset<'tcx>(&self, val: u64, i: u64) -> InterpResult<'tcx, u64> { + let (res, over) = self.overflowing_offset(val, i); + if over { throw_ub!(PointerArithOverflow) } else { Ok(res) } + } + + #[inline] + fn signed_offset<'tcx>(&self, val: u64, i: i64) -> InterpResult<'tcx, u64> { + let (res, over) = self.overflowing_signed_offset(val, i); + if over { throw_ub!(PointerArithOverflow) } else { Ok(res) } + } +} + +impl<T: HasDataLayout> PointerArithmetic for T {} + +/// Represents a pointer in the Miri engine. +/// +/// `Pointer` is generic over the `Tag` associated with each pointer, +/// which is used to do provenance tracking during execution. +#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, TyEncodable, TyDecodable, Hash)] +#[derive(HashStable)] +pub struct Pointer<Tag = ()> { + pub alloc_id: AllocId, + pub offset: Size, + pub tag: Tag, +} + +static_assert_size!(Pointer, 16); + +/// Print the address of a pointer (without the tag) +fn print_ptr_addr<Tag>(ptr: &Pointer<Tag>, f: &mut fmt::Formatter<'_>) -> fmt::Result { + // Forward `alternate` flag to `alloc_id` printing. + if f.alternate() { + write!(f, "{:#?}", ptr.alloc_id)?; + } else { + write!(f, "{:?}", ptr.alloc_id)?; + } + // Print offset only if it is non-zero. + if ptr.offset.bytes() > 0 { + write!(f, "+0x{:x}", ptr.offset.bytes())?; + } + Ok(()) +} + +// We want the `Debug` output to be readable as it is used by `derive(Debug)` for +// all the Miri types. +// We have to use `Debug` output for the tag, because `()` does not implement +// `Display` so we cannot specialize that. +impl<Tag: fmt::Debug> fmt::Debug for Pointer<Tag> { + default fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + print_ptr_addr(self, f)?; + write!(f, "[{:?}]", self.tag) + } +} +// Specialization for no tag +impl fmt::Debug for Pointer<()> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + print_ptr_addr(self, f) + } +} + +impl<Tag: fmt::Debug> fmt::Display for Pointer<Tag> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(self, f) + } +} + +/// Produces a `Pointer` that points to the beginning of the `Allocation`. +impl From<AllocId> for Pointer { + #[inline(always)] + fn from(alloc_id: AllocId) -> Self { + Pointer::new(alloc_id, Size::ZERO) + } +} + +impl Pointer<()> { + #[inline(always)] + pub fn new(alloc_id: AllocId, offset: Size) -> Self { + Pointer { alloc_id, offset, tag: () } + } + + #[inline(always)] + pub fn with_tag<Tag>(self, tag: Tag) -> Pointer<Tag> { + Pointer::new_with_tag(self.alloc_id, self.offset, tag) + } +} + +impl<'tcx, Tag> Pointer<Tag> { + #[inline(always)] + pub fn new_with_tag(alloc_id: AllocId, offset: Size, tag: Tag) -> Self { + Pointer { alloc_id, offset, tag } + } + + #[inline] + pub fn offset(self, i: Size, cx: &impl HasDataLayout) -> InterpResult<'tcx, Self> { + Ok(Pointer::new_with_tag( + self.alloc_id, + Size::from_bytes(cx.data_layout().offset(self.offset.bytes(), i.bytes())?), + self.tag, + )) + } + + #[inline] + pub fn overflowing_offset(self, i: Size, cx: &impl HasDataLayout) -> (Self, bool) { + let (res, over) = cx.data_layout().overflowing_offset(self.offset.bytes(), i.bytes()); + (Pointer::new_with_tag(self.alloc_id, Size::from_bytes(res), self.tag), over) + } + + #[inline(always)] + pub fn wrapping_offset(self, i: Size, cx: &impl HasDataLayout) -> Self { + self.overflowing_offset(i, cx).0 + } + + #[inline] + pub fn signed_offset(self, i: i64, cx: &impl HasDataLayout) -> InterpResult<'tcx, Self> { + Ok(Pointer::new_with_tag( + self.alloc_id, + Size::from_bytes(cx.data_layout().signed_offset(self.offset.bytes(), i)?), + self.tag, + )) + } + + #[inline] + pub fn overflowing_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> (Self, bool) { + let (res, over) = cx.data_layout().overflowing_signed_offset(self.offset.bytes(), i); + (Pointer::new_with_tag(self.alloc_id, Size::from_bytes(res), self.tag), over) + } + + #[inline(always)] + pub fn wrapping_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> Self { + self.overflowing_signed_offset(i, cx).0 + } + + #[inline(always)] + pub fn erase_tag(self) -> Pointer { + Pointer { alloc_id: self.alloc_id, offset: self.offset, tag: () } + } +} diff --git a/compiler/rustc_middle/src/mir/interpret/queries.rs b/compiler/rustc_middle/src/mir/interpret/queries.rs new file mode 100644 index 00000000000..dcc1f8b1a4b --- /dev/null +++ b/compiler/rustc_middle/src/mir/interpret/queries.rs @@ -0,0 +1,100 @@ +use super::{ConstEvalResult, ErrorHandled, GlobalId}; + +use crate::mir; +use crate::ty::subst::{InternalSubsts, SubstsRef}; +use crate::ty::{self, TyCtxt}; +use rustc_hir::def_id::DefId; +use rustc_span::Span; + +impl<'tcx> TyCtxt<'tcx> { + /// Evaluates a constant without providing any substitutions. This is useful to evaluate consts + /// that can't take any generic arguments like statics, const items or enum discriminants. If a + /// generic parameter is used within the constant `ErrorHandled::ToGeneric` will be returned. + pub fn const_eval_poly(self, def_id: DefId) -> ConstEvalResult<'tcx> { + // In some situations def_id will have substitutions within scope, but they aren't allowed + // to be used. So we can't use `Instance::mono`, instead we feed unresolved substitutions + // into `const_eval` which will return `ErrorHandled::ToGeneric` if any of them are + // encountered. + let substs = InternalSubsts::identity_for_item(self, def_id); + let instance = ty::Instance::new(def_id, substs); + let cid = GlobalId { instance, promoted: None }; + let param_env = self.param_env(def_id).with_reveal_all_normalized(self); + self.const_eval_global_id(param_env, cid, None) + } + + /// Resolves and evaluates a constant. + /// + /// The constant can be located on a trait like `<A as B>::C`, in which case the given + /// substitutions and environment are used to resolve the constant. Alternatively if the + /// constant has generic parameters in scope the substitutions are used to evaluate the value of + /// the constant. For example in `fn foo<T>() { let _ = [0; bar::<T>()]; }` the repeat count + /// constant `bar::<T>()` requires a substitution for `T`, if the substitution for `T` is still + /// too generic for the constant to be evaluated then `Err(ErrorHandled::TooGeneric)` is + /// returned. + pub fn const_eval_resolve( + self, + param_env: ty::ParamEnv<'tcx>, + def: ty::WithOptConstParam<DefId>, + substs: SubstsRef<'tcx>, + promoted: Option<mir::Promoted>, + span: Option<Span>, + ) -> ConstEvalResult<'tcx> { + match ty::Instance::resolve_opt_const_arg(self, param_env, def, substs) { + Ok(Some(instance)) => { + let cid = GlobalId { instance, promoted }; + self.const_eval_global_id(param_env, cid, span) + } + Ok(None) => Err(ErrorHandled::TooGeneric), + Err(error_reported) => Err(ErrorHandled::Reported(error_reported)), + } + } + + pub fn const_eval_instance( + self, + param_env: ty::ParamEnv<'tcx>, + instance: ty::Instance<'tcx>, + span: Option<Span>, + ) -> ConstEvalResult<'tcx> { + self.const_eval_global_id(param_env, GlobalId { instance, promoted: None }, span) + } + + /// Evaluate a constant. + pub fn const_eval_global_id( + self, + param_env: ty::ParamEnv<'tcx>, + cid: GlobalId<'tcx>, + span: Option<Span>, + ) -> ConstEvalResult<'tcx> { + // Const-eval shouldn't depend on lifetimes at all, so we can erase them, which should + // improve caching of queries. + let inputs = self.erase_regions(¶m_env.and(cid)); + if let Some(span) = span { + self.at(span).const_eval_validated(inputs) + } else { + self.const_eval_validated(inputs) + } + } + + /// Evaluate a static's initializer, returning the allocation of the initializer's memory. + pub fn eval_static_initializer( + self, + def_id: DefId, + ) -> Result<&'tcx mir::Allocation, ErrorHandled> { + trace!("eval_static_initializer: Need to compute {:?}", def_id); + assert!(self.is_static(def_id)); + let instance = ty::Instance::mono(self, def_id); + let gid = GlobalId { instance, promoted: None }; + self.eval_to_allocation(gid, ty::ParamEnv::reveal_all()) + } + + /// Evaluate anything constant-like, returning the allocation of the final memory. + fn eval_to_allocation( + self, + gid: GlobalId<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> Result<&'tcx mir::Allocation, ErrorHandled> { + trace!("eval_to_allocation: Need to compute {:?}", gid); + let raw_const = self.const_eval_raw(param_env.and(gid))?; + Ok(self.global_alloc(raw_const.alloc_id).unwrap_memory()) + } +} diff --git a/compiler/rustc_middle/src/mir/interpret/value.rs b/compiler/rustc_middle/src/mir/interpret/value.rs new file mode 100644 index 00000000000..7d6ff3eb5c1 --- /dev/null +++ b/compiler/rustc_middle/src/mir/interpret/value.rs @@ -0,0 +1,720 @@ +use std::convert::TryFrom; +use std::fmt; + +use rustc_apfloat::{ + ieee::{Double, Single}, + Float, +}; +use rustc_macros::HashStable; +use rustc_target::abi::{HasDataLayout, Size, TargetDataLayout}; + +use crate::ty::{ParamEnv, Ty, TyCtxt}; + +use super::{sign_extend, truncate, AllocId, Allocation, InterpResult, Pointer, PointerArithmetic}; + +/// Represents the result of a raw const operation, pre-validation. +#[derive(Clone, HashStable)] +pub struct RawConst<'tcx> { + // the value lives here, at offset 0, and that allocation definitely is a `AllocKind::Memory` + // (so you can use `AllocMap::unwrap_memory`). + pub alloc_id: AllocId, + pub ty: Ty<'tcx>, +} + +/// Represents a constant value in Rust. `Scalar` and `Slice` are optimizations for +/// array length computations, enum discriminants and the pattern matching logic. +#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)] +#[derive(HashStable)] +pub enum ConstValue<'tcx> { + /// Used only for types with `layout::abi::Scalar` ABI and ZSTs. + /// + /// Not using the enum `Value` to encode that this must not be `Uninit`. + Scalar(Scalar), + + /// Used only for `&[u8]` and `&str` + Slice { data: &'tcx Allocation, start: usize, end: usize }, + + /// A value not represented/representable by `Scalar` or `Slice` + ByRef { + /// The backing memory of the value, may contain more memory than needed for just the value + /// in order to share `Allocation`s between values + alloc: &'tcx Allocation, + /// Offset into `alloc` + offset: Size, + }, +} + +#[cfg(target_arch = "x86_64")] +static_assert_size!(ConstValue<'_>, 32); + +impl<'tcx> ConstValue<'tcx> { + #[inline] + pub fn try_to_scalar(&self) -> Option<Scalar> { + match *self { + ConstValue::ByRef { .. } | ConstValue::Slice { .. } => None, + ConstValue::Scalar(val) => Some(val), + } + } + + pub fn try_to_str_slice(&self) -> Option<&'tcx str> { + if let ConstValue::Slice { data, start, end } = *self { + ::std::str::from_utf8(data.inspect_with_uninit_and_ptr_outside_interpreter(start..end)) + .ok() + } else { + None + } + } + + pub fn try_to_bits(&self, size: Size) -> Option<u128> { + self.try_to_scalar()?.to_bits(size).ok() + } + + pub fn try_to_bool(&self) -> Option<bool> { + match self.try_to_bits(Size::from_bytes(1))? { + 0 => Some(false), + 1 => Some(true), + _ => None, + } + } + + pub fn try_to_machine_usize(&self, tcx: TyCtxt<'tcx>) -> Option<u64> { + Some(self.try_to_bits(tcx.data_layout.pointer_size)? as u64) + } + + pub fn try_to_bits_for_ty( + &self, + tcx: TyCtxt<'tcx>, + param_env: ParamEnv<'tcx>, + ty: Ty<'tcx>, + ) -> Option<u128> { + let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size; + self.try_to_bits(size) + } + + pub fn from_bool(b: bool) -> Self { + ConstValue::Scalar(Scalar::from_bool(b)) + } + + pub fn from_u64(i: u64) -> Self { + ConstValue::Scalar(Scalar::from_u64(i)) + } + + pub fn from_machine_usize(i: u64, cx: &impl HasDataLayout) -> Self { + ConstValue::Scalar(Scalar::from_machine_usize(i, cx)) + } +} + +/// A `Scalar` represents an immediate, primitive value existing outside of a +/// `memory::Allocation`. It is in many ways like a small chunk of a `Allocation`, up to 8 bytes in +/// size. Like a range of bytes in an `Allocation`, a `Scalar` can either represent the raw bytes +/// of a simple value or a pointer into another `Allocation` +#[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, TyEncodable, TyDecodable, Hash)] +#[derive(HashStable)] +pub enum Scalar<Tag = ()> { + /// The raw bytes of a simple value. + Raw { + /// The first `size` bytes of `data` are the value. + /// Do not try to read less or more bytes than that. The remaining bytes must be 0. + data: u128, + size: u8, + }, + + /// A pointer into an `Allocation`. An `Allocation` in the `memory` module has a list of + /// relocations, but a `Scalar` is only large enough to contain one, so we just represent the + /// relocation and its associated offset together as a `Pointer` here. + Ptr(Pointer<Tag>), +} + +#[cfg(target_arch = "x86_64")] +static_assert_size!(Scalar, 24); + +// We want the `Debug` output to be readable as it is used by `derive(Debug)` for +// all the Miri types. +impl<Tag: fmt::Debug> fmt::Debug for Scalar<Tag> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Scalar::Ptr(ptr) => write!(f, "{:?}", ptr), + &Scalar::Raw { data, size } => { + Scalar::check_data(data, size); + if size == 0 { + write!(f, "<ZST>") + } else { + // Format as hex number wide enough to fit any value of the given `size`. + // So data=20, size=1 will be "0x14", but with size=4 it'll be "0x00000014". + write!(f, "0x{:>0width$x}", data, width = (size * 2) as usize) + } + } + } + } +} + +impl<Tag: fmt::Debug> fmt::Display for Scalar<Tag> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Scalar::Ptr(ptr) => write!(f, "pointer to {}", ptr), + Scalar::Raw { .. } => fmt::Debug::fmt(self, f), + } + } +} + +impl<Tag> From<Single> for Scalar<Tag> { + #[inline(always)] + fn from(f: Single) -> Self { + Scalar::from_f32(f) + } +} + +impl<Tag> From<Double> for Scalar<Tag> { + #[inline(always)] + fn from(f: Double) -> Self { + Scalar::from_f64(f) + } +} + +impl Scalar<()> { + /// Make sure the `data` fits in `size`. + /// This is guaranteed by all constructors here, but since the enum variants are public, + /// it could still be violated (even though no code outside this file should + /// construct `Scalar`s). + #[inline(always)] + fn check_data(data: u128, size: u8) { + debug_assert_eq!( + truncate(data, Size::from_bytes(u64::from(size))), + data, + "Scalar value {:#x} exceeds size of {} bytes", + data, + size + ); + } + + /// Tag this scalar with `new_tag` if it is a pointer, leave it unchanged otherwise. + /// + /// Used by `MemPlace::replace_tag`. + #[inline] + pub fn with_tag<Tag>(self, new_tag: Tag) -> Scalar<Tag> { + match self { + Scalar::Ptr(ptr) => Scalar::Ptr(ptr.with_tag(new_tag)), + Scalar::Raw { data, size } => Scalar::Raw { data, size }, + } + } +} + +impl<'tcx, Tag> Scalar<Tag> { + /// Erase the tag from the scalar, if any. + /// + /// Used by error reporting code to avoid having the error type depend on `Tag`. + #[inline] + pub fn erase_tag(self) -> Scalar { + match self { + Scalar::Ptr(ptr) => Scalar::Ptr(ptr.erase_tag()), + Scalar::Raw { data, size } => Scalar::Raw { data, size }, + } + } + + #[inline] + pub fn null_ptr(cx: &impl HasDataLayout) -> Self { + Scalar::Raw { data: 0, size: cx.data_layout().pointer_size.bytes() as u8 } + } + + #[inline] + pub fn zst() -> Self { + Scalar::Raw { data: 0, size: 0 } + } + + #[inline(always)] + fn ptr_op( + self, + dl: &TargetDataLayout, + f_int: impl FnOnce(u64) -> InterpResult<'tcx, u64>, + f_ptr: impl FnOnce(Pointer<Tag>) -> InterpResult<'tcx, Pointer<Tag>>, + ) -> InterpResult<'tcx, Self> { + match self { + Scalar::Raw { data, size } => { + assert_eq!(u64::from(size), dl.pointer_size.bytes()); + Ok(Scalar::Raw { data: u128::from(f_int(u64::try_from(data).unwrap())?), size }) + } + Scalar::Ptr(ptr) => Ok(Scalar::Ptr(f_ptr(ptr)?)), + } + } + + #[inline] + pub fn ptr_offset(self, i: Size, cx: &impl HasDataLayout) -> InterpResult<'tcx, Self> { + let dl = cx.data_layout(); + self.ptr_op(dl, |int| dl.offset(int, i.bytes()), |ptr| ptr.offset(i, dl)) + } + + #[inline] + pub fn ptr_wrapping_offset(self, i: Size, cx: &impl HasDataLayout) -> Self { + let dl = cx.data_layout(); + self.ptr_op( + dl, + |int| Ok(dl.overflowing_offset(int, i.bytes()).0), + |ptr| Ok(ptr.wrapping_offset(i, dl)), + ) + .unwrap() + } + + #[inline] + pub fn ptr_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> InterpResult<'tcx, Self> { + let dl = cx.data_layout(); + self.ptr_op(dl, |int| dl.signed_offset(int, i), |ptr| ptr.signed_offset(i, dl)) + } + + #[inline] + pub fn ptr_wrapping_signed_offset(self, i: i64, cx: &impl HasDataLayout) -> Self { + let dl = cx.data_layout(); + self.ptr_op( + dl, + |int| Ok(dl.overflowing_signed_offset(int, i).0), + |ptr| Ok(ptr.wrapping_signed_offset(i, dl)), + ) + .unwrap() + } + + #[inline] + pub fn from_bool(b: bool) -> Self { + // Guaranteed to be truncated and does not need sign extension. + Scalar::Raw { data: b as u128, size: 1 } + } + + #[inline] + pub fn from_char(c: char) -> Self { + // Guaranteed to be truncated and does not need sign extension. + Scalar::Raw { data: c as u128, size: 4 } + } + + #[inline] + pub fn try_from_uint(i: impl Into<u128>, size: Size) -> Option<Self> { + let i = i.into(); + if truncate(i, size) == i { + Some(Scalar::Raw { data: i, size: size.bytes() as u8 }) + } else { + None + } + } + + #[inline] + pub fn from_uint(i: impl Into<u128>, size: Size) -> Self { + let i = i.into(); + Self::try_from_uint(i, size) + .unwrap_or_else(|| bug!("Unsigned value {:#x} does not fit in {} bits", i, size.bits())) + } + + #[inline] + pub fn from_u8(i: u8) -> Self { + // Guaranteed to be truncated and does not need sign extension. + Scalar::Raw { data: i.into(), size: 1 } + } + + #[inline] + pub fn from_u16(i: u16) -> Self { + // Guaranteed to be truncated and does not need sign extension. + Scalar::Raw { data: i.into(), size: 2 } + } + + #[inline] + pub fn from_u32(i: u32) -> Self { + // Guaranteed to be truncated and does not need sign extension. + Scalar::Raw { data: i.into(), size: 4 } + } + + #[inline] + pub fn from_u64(i: u64) -> Self { + // Guaranteed to be truncated and does not need sign extension. + Scalar::Raw { data: i.into(), size: 8 } + } + + #[inline] + pub fn from_machine_usize(i: u64, cx: &impl HasDataLayout) -> Self { + Self::from_uint(i, cx.data_layout().pointer_size) + } + + #[inline] + pub fn try_from_int(i: impl Into<i128>, size: Size) -> Option<Self> { + let i = i.into(); + // `into` performed sign extension, we have to truncate + let truncated = truncate(i as u128, size); + if sign_extend(truncated, size) as i128 == i { + Some(Scalar::Raw { data: truncated, size: size.bytes() as u8 }) + } else { + None + } + } + + #[inline] + pub fn from_int(i: impl Into<i128>, size: Size) -> Self { + let i = i.into(); + Self::try_from_int(i, size) + .unwrap_or_else(|| bug!("Signed value {:#x} does not fit in {} bits", i, size.bits())) + } + + #[inline] + pub fn from_i8(i: i8) -> Self { + Self::from_int(i, Size::from_bits(8)) + } + + #[inline] + pub fn from_i16(i: i16) -> Self { + Self::from_int(i, Size::from_bits(16)) + } + + #[inline] + pub fn from_i32(i: i32) -> Self { + Self::from_int(i, Size::from_bits(32)) + } + + #[inline] + pub fn from_i64(i: i64) -> Self { + Self::from_int(i, Size::from_bits(64)) + } + + #[inline] + pub fn from_machine_isize(i: i64, cx: &impl HasDataLayout) -> Self { + Self::from_int(i, cx.data_layout().pointer_size) + } + + #[inline] + pub fn from_f32(f: Single) -> Self { + // We trust apfloat to give us properly truncated data. + Scalar::Raw { data: f.to_bits(), size: 4 } + } + + #[inline] + pub fn from_f64(f: Double) -> Self { + // We trust apfloat to give us properly truncated data. + Scalar::Raw { data: f.to_bits(), size: 8 } + } + + /// This is very rarely the method you want! You should dispatch on the type + /// and use `force_bits`/`assert_bits`/`force_ptr`/`assert_ptr`. + /// This method only exists for the benefit of low-level memory operations + /// as well as the implementation of the `force_*` methods. + #[inline] + pub fn to_bits_or_ptr( + self, + target_size: Size, + cx: &impl HasDataLayout, + ) -> Result<u128, Pointer<Tag>> { + assert_ne!(target_size.bytes(), 0, "you should never look at the bits of a ZST"); + match self { + Scalar::Raw { data, size } => { + assert_eq!(target_size.bytes(), u64::from(size)); + Scalar::check_data(data, size); + Ok(data) + } + Scalar::Ptr(ptr) => { + assert_eq!(target_size, cx.data_layout().pointer_size); + Err(ptr) + } + } + } + + /// This method is intentionally private! + /// It is just a helper for other methods in this file. + #[inline] + fn to_bits(self, target_size: Size) -> InterpResult<'tcx, u128> { + assert_ne!(target_size.bytes(), 0, "you should never look at the bits of a ZST"); + match self { + Scalar::Raw { data, size } => { + if target_size.bytes() != u64::from(size) { + throw_ub!(ScalarSizeMismatch { + target_size: target_size.bytes(), + data_size: u64::from(size), + }); + } + Scalar::check_data(data, size); + Ok(data) + } + Scalar::Ptr(_) => throw_unsup!(ReadPointerAsBytes), + } + } + + #[inline(always)] + pub fn assert_bits(self, target_size: Size) -> u128 { + self.to_bits(target_size).expect("expected Raw bits but got a Pointer") + } + + #[inline] + pub fn assert_ptr(self) -> Pointer<Tag> { + match self { + Scalar::Ptr(p) => p, + Scalar::Raw { .. } => bug!("expected a Pointer but got Raw bits"), + } + } + + /// Do not call this method! Dispatch based on the type instead. + #[inline] + pub fn is_bits(self) -> bool { + match self { + Scalar::Raw { .. } => true, + _ => false, + } + } + + /// Do not call this method! Dispatch based on the type instead. + #[inline] + pub fn is_ptr(self) -> bool { + match self { + Scalar::Ptr(_) => true, + _ => false, + } + } + + pub fn to_bool(self) -> InterpResult<'tcx, bool> { + let val = self.to_u8()?; + match val { + 0 => Ok(false), + 1 => Ok(true), + _ => throw_ub!(InvalidBool(val)), + } + } + + pub fn to_char(self) -> InterpResult<'tcx, char> { + let val = self.to_u32()?; + match ::std::char::from_u32(val) { + Some(c) => Ok(c), + None => throw_ub!(InvalidChar(val)), + } + } + + #[inline] + fn to_unsigned_with_bit_width(self, bits: u64) -> InterpResult<'static, u128> { + let sz = Size::from_bits(bits); + self.to_bits(sz) + } + + /// Converts the scalar to produce an `u8`. Fails if the scalar is a pointer. + pub fn to_u8(self) -> InterpResult<'static, u8> { + self.to_unsigned_with_bit_width(8).map(|v| u8::try_from(v).unwrap()) + } + + /// Converts the scalar to produce an `u16`. Fails if the scalar is a pointer. + pub fn to_u16(self) -> InterpResult<'static, u16> { + self.to_unsigned_with_bit_width(16).map(|v| u16::try_from(v).unwrap()) + } + + /// Converts the scalar to produce an `u32`. Fails if the scalar is a pointer. + pub fn to_u32(self) -> InterpResult<'static, u32> { + self.to_unsigned_with_bit_width(32).map(|v| u32::try_from(v).unwrap()) + } + + /// Converts the scalar to produce an `u64`. Fails if the scalar is a pointer. + pub fn to_u64(self) -> InterpResult<'static, u64> { + self.to_unsigned_with_bit_width(64).map(|v| u64::try_from(v).unwrap()) + } + + /// Converts the scalar to produce an `u128`. Fails if the scalar is a pointer. + pub fn to_u128(self) -> InterpResult<'static, u128> { + self.to_unsigned_with_bit_width(128) + } + + pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'static, u64> { + let b = self.to_bits(cx.data_layout().pointer_size)?; + Ok(u64::try_from(b).unwrap()) + } + + #[inline] + fn to_signed_with_bit_width(self, bits: u64) -> InterpResult<'static, i128> { + let sz = Size::from_bits(bits); + let b = self.to_bits(sz)?; + Ok(sign_extend(b, sz) as i128) + } + + /// Converts the scalar to produce an `i8`. Fails if the scalar is a pointer. + pub fn to_i8(self) -> InterpResult<'static, i8> { + self.to_signed_with_bit_width(8).map(|v| i8::try_from(v).unwrap()) + } + + /// Converts the scalar to produce an `i16`. Fails if the scalar is a pointer. + pub fn to_i16(self) -> InterpResult<'static, i16> { + self.to_signed_with_bit_width(16).map(|v| i16::try_from(v).unwrap()) + } + + /// Converts the scalar to produce an `i32`. Fails if the scalar is a pointer. + pub fn to_i32(self) -> InterpResult<'static, i32> { + self.to_signed_with_bit_width(32).map(|v| i32::try_from(v).unwrap()) + } + + /// Converts the scalar to produce an `i64`. Fails if the scalar is a pointer. + pub fn to_i64(self) -> InterpResult<'static, i64> { + self.to_signed_with_bit_width(64).map(|v| i64::try_from(v).unwrap()) + } + + /// Converts the scalar to produce an `i128`. Fails if the scalar is a pointer. + pub fn to_i128(self) -> InterpResult<'static, i128> { + self.to_signed_with_bit_width(128) + } + + pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'static, i64> { + let sz = cx.data_layout().pointer_size; + let b = self.to_bits(sz)?; + let b = sign_extend(b, sz) as i128; + Ok(i64::try_from(b).unwrap()) + } + + #[inline] + pub fn to_f32(self) -> InterpResult<'static, Single> { + // Going through `u32` to check size and truncation. + Ok(Single::from_bits(self.to_u32()?.into())) + } + + #[inline] + pub fn to_f64(self) -> InterpResult<'static, Double> { + // Going through `u64` to check size and truncation. + Ok(Double::from_bits(self.to_u64()?.into())) + } +} + +impl<Tag> From<Pointer<Tag>> for Scalar<Tag> { + #[inline(always)] + fn from(ptr: Pointer<Tag>) -> Self { + Scalar::Ptr(ptr) + } +} + +#[derive(Clone, Copy, Eq, PartialEq, TyEncodable, TyDecodable, HashStable, Hash)] +pub enum ScalarMaybeUninit<Tag = ()> { + Scalar(Scalar<Tag>), + Uninit, +} + +impl<Tag> From<Scalar<Tag>> for ScalarMaybeUninit<Tag> { + #[inline(always)] + fn from(s: Scalar<Tag>) -> Self { + ScalarMaybeUninit::Scalar(s) + } +} + +impl<Tag> From<Pointer<Tag>> for ScalarMaybeUninit<Tag> { + #[inline(always)] + fn from(s: Pointer<Tag>) -> Self { + ScalarMaybeUninit::Scalar(s.into()) + } +} + +// We want the `Debug` output to be readable as it is used by `derive(Debug)` for +// all the Miri types. +impl<Tag: fmt::Debug> fmt::Debug for ScalarMaybeUninit<Tag> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + ScalarMaybeUninit::Uninit => write!(f, "<uninitialized>"), + ScalarMaybeUninit::Scalar(s) => write!(f, "{:?}", s), + } + } +} + +impl<Tag: fmt::Debug> fmt::Display for ScalarMaybeUninit<Tag> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + ScalarMaybeUninit::Uninit => write!(f, "uninitialized bytes"), + ScalarMaybeUninit::Scalar(s) => write!(f, "{}", s), + } + } +} + +impl<'tcx, Tag> ScalarMaybeUninit<Tag> { + /// Erase the tag from the scalar, if any. + /// + /// Used by error reporting code to avoid having the error type depend on `Tag`. + #[inline] + pub fn erase_tag(self) -> ScalarMaybeUninit { + match self { + ScalarMaybeUninit::Scalar(s) => ScalarMaybeUninit::Scalar(s.erase_tag()), + ScalarMaybeUninit::Uninit => ScalarMaybeUninit::Uninit, + } + } + + #[inline] + pub fn check_init(self) -> InterpResult<'static, Scalar<Tag>> { + match self { + ScalarMaybeUninit::Scalar(scalar) => Ok(scalar), + ScalarMaybeUninit::Uninit => throw_ub!(InvalidUninitBytes(None)), + } + } + + #[inline(always)] + pub fn to_bool(self) -> InterpResult<'tcx, bool> { + self.check_init()?.to_bool() + } + + #[inline(always)] + pub fn to_char(self) -> InterpResult<'tcx, char> { + self.check_init()?.to_char() + } + + #[inline(always)] + pub fn to_f32(self) -> InterpResult<'tcx, Single> { + self.check_init()?.to_f32() + } + + #[inline(always)] + pub fn to_f64(self) -> InterpResult<'tcx, Double> { + self.check_init()?.to_f64() + } + + #[inline(always)] + pub fn to_u8(self) -> InterpResult<'tcx, u8> { + self.check_init()?.to_u8() + } + + #[inline(always)] + pub fn to_u16(self) -> InterpResult<'tcx, u16> { + self.check_init()?.to_u16() + } + + #[inline(always)] + pub fn to_u32(self) -> InterpResult<'tcx, u32> { + self.check_init()?.to_u32() + } + + #[inline(always)] + pub fn to_u64(self) -> InterpResult<'tcx, u64> { + self.check_init()?.to_u64() + } + + #[inline(always)] + pub fn to_machine_usize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> { + self.check_init()?.to_machine_usize(cx) + } + + #[inline(always)] + pub fn to_i8(self) -> InterpResult<'tcx, i8> { + self.check_init()?.to_i8() + } + + #[inline(always)] + pub fn to_i16(self) -> InterpResult<'tcx, i16> { + self.check_init()?.to_i16() + } + + #[inline(always)] + pub fn to_i32(self) -> InterpResult<'tcx, i32> { + self.check_init()?.to_i32() + } + + #[inline(always)] + pub fn to_i64(self) -> InterpResult<'tcx, i64> { + self.check_init()?.to_i64() + } + + #[inline(always)] + pub fn to_machine_isize(self, cx: &impl HasDataLayout) -> InterpResult<'tcx, i64> { + self.check_init()?.to_machine_isize(cx) + } +} + +/// Gets the bytes of a constant slice value. +pub fn get_slice_bytes<'tcx>(cx: &impl HasDataLayout, val: ConstValue<'tcx>) -> &'tcx [u8] { + if let ConstValue::Slice { data, start, end } = val { + let len = end - start; + data.get_bytes( + cx, + // invent a pointer, only the offset is relevant anyway + Pointer::new(AllocId(0), Size::from_bytes(start)), + Size::from_bytes(len), + ) + .unwrap_or_else(|err| bug!("const slice is invalid: {:?}", err)) + } else { + bug!("expected const slice, but found another const value"); + } +} diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs new file mode 100644 index 00000000000..785a7f0c51a --- /dev/null +++ b/compiler/rustc_middle/src/mir/mod.rs @@ -0,0 +1,2600 @@ +//! MIR datatypes and passes. See the [rustc dev guide] for more info. +//! +//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/index.html + +use crate::mir::coverage::{CodeRegion, CoverageKind}; +use crate::mir::interpret::{Allocation, ConstValue, GlobalAlloc, Scalar}; +use crate::mir::visit::MirVisitable; +use crate::ty::adjustment::PointerCast; +use crate::ty::codec::{TyDecoder, TyEncoder}; +use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor}; +use crate::ty::print::{FmtPrinter, Printer}; +use crate::ty::subst::{Subst, SubstsRef}; +use crate::ty::{ + self, AdtDef, CanonicalUserTypeAnnotations, List, Region, Ty, TyCtxt, UserTypeAnnotationIndex, +}; +use rustc_hir as hir; +use rustc_hir::def::{CtorKind, Namespace}; +use rustc_hir::def_id::DefId; +use rustc_hir::{self, GeneratorKind}; +use rustc_target::abi::VariantIdx; + +use polonius_engine::Atom; +pub use rustc_ast::Mutability; +use rustc_data_structures::fx::FxHashSet; +use rustc_data_structures::graph::dominators::{dominators, Dominators}; +use rustc_data_structures::graph::{self, GraphSuccessors}; +use rustc_index::bit_set::BitMatrix; +use rustc_index::vec::{Idx, IndexVec}; +use rustc_serialize::{Decodable, Encodable}; +use rustc_span::symbol::Symbol; +use rustc_span::{Span, DUMMY_SP}; +use rustc_target::abi; +use rustc_target::asm::InlineAsmRegOrRegClass; +use std::borrow::Cow; +use std::fmt::{self, Debug, Display, Formatter, Write}; +use std::ops::{Index, IndexMut}; +use std::slice; +use std::{iter, mem, option}; + +use self::predecessors::{PredecessorCache, Predecessors}; +pub use self::query::*; + +pub mod coverage; +pub mod interpret; +pub mod mono; +mod predecessors; +mod query; +pub mod tcx; +pub mod terminator; +pub use terminator::*; +pub mod traversal; +mod type_foldable; +pub mod visit; + +/// Types for locals +type LocalDecls<'tcx> = IndexVec<Local, LocalDecl<'tcx>>; + +pub trait HasLocalDecls<'tcx> { + fn local_decls(&self) -> &LocalDecls<'tcx>; +} + +impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> { + fn local_decls(&self) -> &LocalDecls<'tcx> { + self + } +} + +impl<'tcx> HasLocalDecls<'tcx> for Body<'tcx> { + fn local_decls(&self) -> &LocalDecls<'tcx> { + &self.local_decls + } +} + +/// The various "big phases" that MIR goes through. +/// +/// These phases all describe dialects of MIR. Since all MIR uses the same datastructures, the +/// dialects forbid certain variants or values in certain phases. +/// +/// Note: Each phase's validation checks all invariants of the *previous* phases' dialects. A phase +/// that changes the dialect documents what invariants must be upheld *after* that phase finishes. +/// +/// Warning: ordering of variants is significant. +#[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, PartialEq, Eq, PartialOrd, Ord)] +#[derive(HashStable)] +pub enum MirPhase { + Build = 0, + // FIXME(oli-obk): it's unclear whether we still need this phase (and its corresponding query). + // We used to have this for pre-miri MIR based const eval. + Const = 1, + /// This phase checks the MIR for promotable elements and takes them out of the main MIR body + /// by creating a new MIR body per promoted element. After this phase (and thus the termination + /// of the `mir_promoted` query), these promoted elements are available in the `promoted_mir` + /// query. + ConstPromotion = 2, + /// After this phase + /// * the only `AggregateKind`s allowed are `Array` and `Generator`, + /// * `DropAndReplace` is gone for good + /// * `Drop` now uses explicit drop flags visible in the MIR and reaching a `Drop` terminator + /// means that the auto-generated drop glue will be invoked. + DropLowering = 3, + /// After this phase, generators are explicit state machines (no more `Yield`). + /// `AggregateKind::Generator` is gone for good. + GeneratorLowering = 4, + Optimization = 5, +} + +impl MirPhase { + /// Gets the index of the current MirPhase within the set of all `MirPhase`s. + pub fn phase_index(&self) -> usize { + *self as usize + } +} + +/// The lowered representation of a single function. +#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable, TypeFoldable)] +pub struct Body<'tcx> { + /// A list of basic blocks. References to basic block use a newtyped index type `BasicBlock` + /// that indexes into this vector. + basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>, + + /// Records how far through the "desugaring and optimization" process this particular + /// MIR has traversed. This is particularly useful when inlining, since in that context + /// we instantiate the promoted constants and add them to our promoted vector -- but those + /// promoted items have already been optimized, whereas ours have not. This field allows + /// us to see the difference and forego optimization on the inlined promoted items. + pub phase: MirPhase, + + /// A list of source scopes; these are referenced by statements + /// and used for debuginfo. Indexed by a `SourceScope`. + pub source_scopes: IndexVec<SourceScope, SourceScopeData>, + + /// The yield type of the function, if it is a generator. + pub yield_ty: Option<Ty<'tcx>>, + + /// Generator drop glue. + pub generator_drop: Option<Box<Body<'tcx>>>, + + /// The layout of a generator. Produced by the state transformation. + pub generator_layout: Option<GeneratorLayout<'tcx>>, + + /// If this is a generator then record the type of source expression that caused this generator + /// to be created. + pub generator_kind: Option<GeneratorKind>, + + /// Declarations of locals. + /// + /// The first local is the return value pointer, followed by `arg_count` + /// locals for the function arguments, followed by any user-declared + /// variables and temporaries. + pub local_decls: LocalDecls<'tcx>, + + /// User type annotations. + pub user_type_annotations: CanonicalUserTypeAnnotations<'tcx>, + + /// The number of arguments this function takes. + /// + /// Starting at local 1, `arg_count` locals will be provided by the caller + /// and can be assumed to be initialized. + /// + /// If this MIR was built for a constant, this will be 0. + pub arg_count: usize, + + /// Mark an argument local (which must be a tuple) as getting passed as + /// its individual components at the LLVM level. + /// + /// This is used for the "rust-call" ABI. + pub spread_arg: Option<Local>, + + /// Debug information pertaining to user variables, including captures. + pub var_debug_info: Vec<VarDebugInfo<'tcx>>, + + /// A span representing this MIR, for error reporting. + pub span: Span, + + /// Constants that are required to evaluate successfully for this MIR to be well-formed. + /// We hold in this field all the constants we are not able to evaluate yet. + pub required_consts: Vec<Constant<'tcx>>, + + /// The user may be writing e.g. `&[(SOME_CELL, 42)][i].1` and this would get promoted, because + /// we'd statically know that no thing with interior mutability will ever be available to the + /// user without some serious unsafe code. Now this means that our promoted is actually + /// `&[(SOME_CELL, 42)]` and the MIR using it will do the `&promoted[i].1` projection because + /// the index may be a runtime value. Such a promoted value is illegal because it has reachable + /// interior mutability. This flag just makes this situation very obvious where the previous + /// implementation without the flag hid this situation silently. + /// FIXME(oli-obk): rewrite the promoted during promotion to eliminate the cell components. + pub ignore_interior_mut_in_const_validation: bool, + + predecessor_cache: PredecessorCache, +} + +impl<'tcx> Body<'tcx> { + pub fn new( + basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>, + source_scopes: IndexVec<SourceScope, SourceScopeData>, + local_decls: LocalDecls<'tcx>, + user_type_annotations: CanonicalUserTypeAnnotations<'tcx>, + arg_count: usize, + var_debug_info: Vec<VarDebugInfo<'tcx>>, + span: Span, + generator_kind: Option<GeneratorKind>, + ) -> Self { + // We need `arg_count` locals, and one for the return place. + assert!( + local_decls.len() > arg_count, + "expected at least {} locals, got {}", + arg_count + 1, + local_decls.len() + ); + + Body { + phase: MirPhase::Build, + basic_blocks, + source_scopes, + yield_ty: None, + generator_drop: None, + generator_layout: None, + generator_kind, + local_decls, + user_type_annotations, + arg_count, + spread_arg: None, + var_debug_info, + span, + required_consts: Vec::new(), + ignore_interior_mut_in_const_validation: false, + predecessor_cache: PredecessorCache::new(), + } + } + + /// Returns a partially initialized MIR body containing only a list of basic blocks. + /// + /// The returned MIR contains no `LocalDecl`s (even for the return place) or source scopes. It + /// is only useful for testing but cannot be `#[cfg(test)]` because it is used in a different + /// crate. + pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self { + Body { + phase: MirPhase::Build, + basic_blocks, + source_scopes: IndexVec::new(), + yield_ty: None, + generator_drop: None, + generator_layout: None, + local_decls: IndexVec::new(), + user_type_annotations: IndexVec::new(), + arg_count: 0, + spread_arg: None, + span: DUMMY_SP, + required_consts: Vec::new(), + generator_kind: None, + var_debug_info: Vec::new(), + ignore_interior_mut_in_const_validation: false, + predecessor_cache: PredecessorCache::new(), + } + } + + #[inline] + pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> { + &self.basic_blocks + } + + #[inline] + pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> { + // Because the user could mutate basic block terminators via this reference, we need to + // invalidate the predecessor cache. + // + // FIXME: Use a finer-grained API for this, so only transformations that alter terminators + // invalidate the predecessor cache. + self.predecessor_cache.invalidate(); + &mut self.basic_blocks + } + + #[inline] + pub fn basic_blocks_and_local_decls_mut( + &mut self, + ) -> (&mut IndexVec<BasicBlock, BasicBlockData<'tcx>>, &mut LocalDecls<'tcx>) { + self.predecessor_cache.invalidate(); + (&mut self.basic_blocks, &mut self.local_decls) + } + + #[inline] + pub fn basic_blocks_local_decls_mut_and_var_debug_info( + &mut self, + ) -> ( + &mut IndexVec<BasicBlock, BasicBlockData<'tcx>>, + &mut LocalDecls<'tcx>, + &mut Vec<VarDebugInfo<'tcx>>, + ) { + self.predecessor_cache.invalidate(); + (&mut self.basic_blocks, &mut self.local_decls, &mut self.var_debug_info) + } + + /// Returns `true` if a cycle exists in the control-flow graph that is reachable from the + /// `START_BLOCK`. + pub fn is_cfg_cyclic(&self) -> bool { + graph::is_cyclic(self) + } + + #[inline] + pub fn local_kind(&self, local: Local) -> LocalKind { + let index = local.as_usize(); + if index == 0 { + debug_assert!( + self.local_decls[local].mutability == Mutability::Mut, + "return place should be mutable" + ); + + LocalKind::ReturnPointer + } else if index < self.arg_count + 1 { + LocalKind::Arg + } else if self.local_decls[local].is_user_variable() { + LocalKind::Var + } else { + LocalKind::Temp + } + } + + /// Returns an iterator over all temporaries. + #[inline] + pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a { + (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| { + let local = Local::new(index); + if self.local_decls[local].is_user_variable() { None } else { Some(local) } + }) + } + + /// Returns an iterator over all user-declared locals. + #[inline] + pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a { + (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| { + let local = Local::new(index); + self.local_decls[local].is_user_variable().then_some(local) + }) + } + + /// Returns an iterator over all user-declared mutable locals. + #[inline] + pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a { + (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| { + let local = Local::new(index); + let decl = &self.local_decls[local]; + if decl.is_user_variable() && decl.mutability == Mutability::Mut { + Some(local) + } else { + None + } + }) + } + + /// Returns an iterator over all user-declared mutable arguments and locals. + #[inline] + pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a { + (1..self.local_decls.len()).filter_map(move |index| { + let local = Local::new(index); + let decl = &self.local_decls[local]; + if (decl.is_user_variable() || index < self.arg_count + 1) + && decl.mutability == Mutability::Mut + { + Some(local) + } else { + None + } + }) + } + + /// Returns an iterator over all function arguments. + #[inline] + pub fn args_iter(&self) -> impl Iterator<Item = Local> + ExactSizeIterator { + let arg_count = self.arg_count; + (1..arg_count + 1).map(Local::new) + } + + /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all + /// locals that are neither arguments nor the return place). + #[inline] + pub fn vars_and_temps_iter(&self) -> impl Iterator<Item = Local> + ExactSizeIterator { + let arg_count = self.arg_count; + let local_count = self.local_decls.len(); + (arg_count + 1..local_count).map(Local::new) + } + + /// Changes a statement to a nop. This is both faster than deleting instructions and avoids + /// invalidating statement indices in `Location`s. + pub fn make_statement_nop(&mut self, location: Location) { + let block = &mut self.basic_blocks[location.block]; + debug_assert!(location.statement_index < block.statements.len()); + block.statements[location.statement_index].make_nop() + } + + /// Returns the source info associated with `location`. + pub fn source_info(&self, location: Location) -> &SourceInfo { + let block = &self[location.block]; + let stmts = &block.statements; + let idx = location.statement_index; + if idx < stmts.len() { + &stmts[idx].source_info + } else { + assert_eq!(idx, stmts.len()); + &block.terminator().source_info + } + } + + /// Checks if `sub` is a sub scope of `sup` + pub fn is_sub_scope(&self, mut sub: SourceScope, sup: SourceScope) -> bool { + while sub != sup { + match self.source_scopes[sub].parent_scope { + None => return false, + Some(p) => sub = p, + } + } + true + } + + /// Returns the return type; it always return first element from `local_decls` array. + #[inline] + pub fn return_ty(&self) -> Ty<'tcx> { + self.local_decls[RETURN_PLACE].ty + } + + /// Gets the location of the terminator for the given block. + #[inline] + pub fn terminator_loc(&self, bb: BasicBlock) -> Location { + Location { block: bb, statement_index: self[bb].statements.len() } + } + + #[inline] + pub fn predecessors(&self) -> impl std::ops::Deref<Target = Predecessors> + '_ { + self.predecessor_cache.compute(&self.basic_blocks) + } + + #[inline] + pub fn dominators(&self) -> Dominators<BasicBlock> { + dominators(self) + } +} + +#[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum Safety { + Safe, + /// Unsafe because of a PushUnsafeBlock + BuiltinUnsafe, + /// Unsafe because of an unsafe fn + FnUnsafe, + /// Unsafe because of an `unsafe` block + ExplicitUnsafe(hir::HirId), +} + +impl<'tcx> Index<BasicBlock> for Body<'tcx> { + type Output = BasicBlockData<'tcx>; + + #[inline] + fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> { + &self.basic_blocks()[index] + } +} + +impl<'tcx> IndexMut<BasicBlock> for Body<'tcx> { + #[inline] + fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> { + &mut self.basic_blocks_mut()[index] + } +} + +#[derive(Copy, Clone, Debug, HashStable, TypeFoldable)] +pub enum ClearCrossCrate<T> { + Clear, + Set(T), +} + +impl<T> ClearCrossCrate<T> { + pub fn as_ref(&self) -> ClearCrossCrate<&T> { + match self { + ClearCrossCrate::Clear => ClearCrossCrate::Clear, + ClearCrossCrate::Set(v) => ClearCrossCrate::Set(v), + } + } + + pub fn assert_crate_local(self) -> T { + match self { + ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"), + ClearCrossCrate::Set(v) => v, + } + } +} + +const TAG_CLEAR_CROSS_CRATE_CLEAR: u8 = 0; +const TAG_CLEAR_CROSS_CRATE_SET: u8 = 1; + +impl<'tcx, E: TyEncoder<'tcx>, T: Encodable<E>> Encodable<E> for ClearCrossCrate<T> { + #[inline] + fn encode(&self, e: &mut E) -> Result<(), E::Error> { + if E::CLEAR_CROSS_CRATE { + return Ok(()); + } + + match *self { + ClearCrossCrate::Clear => TAG_CLEAR_CROSS_CRATE_CLEAR.encode(e), + ClearCrossCrate::Set(ref val) => { + TAG_CLEAR_CROSS_CRATE_SET.encode(e)?; + val.encode(e) + } + } + } +} +impl<'tcx, D: TyDecoder<'tcx>, T: Decodable<D>> Decodable<D> for ClearCrossCrate<T> { + #[inline] + fn decode(d: &mut D) -> Result<ClearCrossCrate<T>, D::Error> { + if D::CLEAR_CROSS_CRATE { + return Ok(ClearCrossCrate::Clear); + } + + let discr = u8::decode(d)?; + + match discr { + TAG_CLEAR_CROSS_CRATE_CLEAR => Ok(ClearCrossCrate::Clear), + TAG_CLEAR_CROSS_CRATE_SET => { + let val = T::decode(d)?; + Ok(ClearCrossCrate::Set(val)) + } + tag => Err(d.error(&format!("Invalid tag for ClearCrossCrate: {:?}", tag))), + } + } +} + +/// Grouped information about the source code origin of a MIR entity. +/// Intended to be inspected by diagnostics and debuginfo. +/// Most passes can work with it as a whole, within a single function. +// The unofficial Cranelift backend, at least as of #65828, needs `SourceInfo` to implement `Eq` and +// `Hash`. Please ping @bjorn3 if removing them. +#[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)] +pub struct SourceInfo { + /// The source span for the AST pertaining to this MIR entity. + pub span: Span, + + /// The source scope, keeping track of which bindings can be + /// seen by debuginfo, active lint levels, `unsafe {...}`, etc. + pub scope: SourceScope, +} + +impl SourceInfo { + #[inline] + pub fn outermost(span: Span) -> Self { + SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE } + } +} + +/////////////////////////////////////////////////////////////////////////// +// Borrow kinds + +#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub enum BorrowKind { + /// Data must be immutable and is aliasable. + Shared, + + /// The immediately borrowed place must be immutable, but projections from + /// it don't need to be. For example, a shallow borrow of `a.b` doesn't + /// conflict with a mutable borrow of `a.b.c`. + /// + /// This is used when lowering matches: when matching on a place we want to + /// ensure that place have the same value from the start of the match until + /// an arm is selected. This prevents this code from compiling: + /// + /// let mut x = &Some(0); + /// match *x { + /// None => (), + /// Some(_) if { x = &None; false } => (), + /// Some(_) => (), + /// } + /// + /// This can't be a shared borrow because mutably borrowing (*x as Some).0 + /// should not prevent `if let None = x { ... }`, for example, because the + /// mutating `(*x as Some).0` can't affect the discriminant of `x`. + /// We can also report errors with this kind of borrow differently. + Shallow, + + /// Data must be immutable but not aliasable. This kind of borrow + /// cannot currently be expressed by the user and is used only in + /// implicit closure bindings. It is needed when the closure is + /// borrowing or mutating a mutable referent, e.g.: + /// + /// let x: &mut isize = ...; + /// let y = || *x += 5; + /// + /// If we were to try to translate this closure into a more explicit + /// form, we'd encounter an error with the code as written: + /// + /// struct Env { x: & &mut isize } + /// let x: &mut isize = ...; + /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn + /// fn fn_ptr(env: &mut Env) { **env.x += 5; } + /// + /// This is then illegal because you cannot mutate an `&mut` found + /// in an aliasable location. To solve, you'd have to translate with + /// an `&mut` borrow: + /// + /// struct Env { x: & &mut isize } + /// let x: &mut isize = ...; + /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x + /// fn fn_ptr(env: &mut Env) { **env.x += 5; } + /// + /// Now the assignment to `**env.x` is legal, but creating a + /// mutable pointer to `x` is not because `x` is not mutable. We + /// could fix this by declaring `x` as `let mut x`. This is ok in + /// user code, if awkward, but extra weird for closures, since the + /// borrow is hidden. + /// + /// So we introduce a "unique imm" borrow -- the referent is + /// immutable, but not aliasable. This solves the problem. For + /// simplicity, we don't give users the way to express this + /// borrow, it's just used when translating closures. + Unique, + + /// Data is mutable and not aliasable. + Mut { + /// `true` if this borrow arose from method-call auto-ref + /// (i.e., `adjustment::Adjust::Borrow`). + allow_two_phase_borrow: bool, + }, +} + +impl BorrowKind { + pub fn allows_two_phase_borrow(&self) -> bool { + match *self { + BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false, + BorrowKind::Mut { allow_two_phase_borrow } => allow_two_phase_borrow, + } + } +} + +/////////////////////////////////////////////////////////////////////////// +// Variables and temps + +rustc_index::newtype_index! { + pub struct Local { + derive [HashStable] + DEBUG_FORMAT = "_{}", + const RETURN_PLACE = 0, + } +} + +impl Atom for Local { + fn index(self) -> usize { + Idx::index(self) + } +} + +/// Classifies locals into categories. See `Body::local_kind`. +#[derive(PartialEq, Eq, Debug, HashStable)] +pub enum LocalKind { + /// User-declared variable binding. + Var, + /// Compiler-introduced temporary. + Temp, + /// Function argument. + Arg, + /// Location of function's return value. + ReturnPointer, +} + +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct VarBindingForm<'tcx> { + /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`? + pub binding_mode: ty::BindingMode, + /// If an explicit type was provided for this variable binding, + /// this holds the source Span of that type. + /// + /// NOTE: if you want to change this to a `HirId`, be wary that + /// doing so breaks incremental compilation (as of this writing), + /// while a `Span` does not cause our tests to fail. + pub opt_ty_info: Option<Span>, + /// Place of the RHS of the =, or the subject of the `match` where this + /// variable is initialized. None in the case of `let PATTERN;`. + /// Some((None, ..)) in the case of and `let [mut] x = ...` because + /// (a) the right-hand side isn't evaluated as a place expression. + /// (b) it gives a way to separate this case from the remaining cases + /// for diagnostics. + pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>, + /// The span of the pattern in which this variable was bound. + pub pat_span: Span, +} + +#[derive(Clone, Debug, TyEncodable, TyDecodable)] +pub enum BindingForm<'tcx> { + /// This is a binding for a non-`self` binding, or a `self` that has an explicit type. + Var(VarBindingForm<'tcx>), + /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit. + ImplicitSelf(ImplicitSelfKind), + /// Reference used in a guard expression to ensure immutability. + RefForGuard, +} + +/// Represents what type of implicit self a function has, if any. +#[derive(Clone, Copy, PartialEq, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum ImplicitSelfKind { + /// Represents a `fn x(self);`. + Imm, + /// Represents a `fn x(mut self);`. + Mut, + /// Represents a `fn x(&self);`. + ImmRef, + /// Represents a `fn x(&mut self);`. + MutRef, + /// Represents when a function does not have a self argument or + /// when a function has a `self: X` argument. + None, +} + +CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, } + +mod binding_form_impl { + use crate::ich::StableHashingContext; + use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; + + impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + use super::BindingForm::*; + ::std::mem::discriminant(self).hash_stable(hcx, hasher); + + match self { + Var(binding) => binding.hash_stable(hcx, hasher), + ImplicitSelf(kind) => kind.hash_stable(hcx, hasher), + RefForGuard => (), + } + } + } +} + +/// `BlockTailInfo` is attached to the `LocalDecl` for temporaries +/// created during evaluation of expressions in a block tail +/// expression; that is, a block like `{ STMT_1; STMT_2; EXPR }`. +/// +/// It is used to improve diagnostics when such temporaries are +/// involved in borrow_check errors, e.g., explanations of where the +/// temporaries come from, when their destructors are run, and/or how +/// one might revise the code to satisfy the borrow checker's rules. +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct BlockTailInfo { + /// If `true`, then the value resulting from evaluating this tail + /// expression is ignored by the block's expression context. + /// + /// Examples include `{ ...; tail };` and `let _ = { ...; tail };` + /// but not e.g., `let _x = { ...; tail };` + pub tail_result_is_ignored: bool, + + /// `Span` of the tail expression. + pub span: Span, +} + +/// A MIR local. +/// +/// This can be a binding declared by the user, a temporary inserted by the compiler, a function +/// argument, or the return place. +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct LocalDecl<'tcx> { + /// Whether this is a mutable minding (i.e., `let x` or `let mut x`). + /// + /// Temporaries and the return place are always mutable. + pub mutability: Mutability, + + // FIXME(matthewjasper) Don't store in this in `Body` + pub local_info: Option<Box<LocalInfo<'tcx>>>, + + /// `true` if this is an internal local. + /// + /// These locals are not based on types in the source code and are only used + /// for a few desugarings at the moment. + /// + /// The generator transformation will sanity check the locals which are live + /// across a suspension point against the type components of the generator + /// which type checking knows are live across a suspension point. We need to + /// flag drop flags to avoid triggering this check as they are introduced + /// after typeck. + /// + /// Unsafety checking will also ignore dereferences of these locals, + /// so they can be used for raw pointers only used in a desugaring. + /// + /// This should be sound because the drop flags are fully algebraic, and + /// therefore don't affect the OIBIT or outlives properties of the + /// generator. + pub internal: bool, + + /// If this local is a temporary and `is_block_tail` is `Some`, + /// then it is a temporary created for evaluation of some + /// subexpression of some block's tail expression (with no + /// intervening statement context). + // FIXME(matthewjasper) Don't store in this in `Body` + pub is_block_tail: Option<BlockTailInfo>, + + /// The type of this local. + pub ty: Ty<'tcx>, + + /// If the user manually ascribed a type to this variable, + /// e.g., via `let x: T`, then we carry that type here. The MIR + /// borrow checker needs this information since it can affect + /// region inference. + // FIXME(matthewjasper) Don't store in this in `Body` + pub user_ty: Option<Box<UserTypeProjections>>, + + /// The *syntactic* (i.e., not visibility) source scope the local is defined + /// in. If the local was defined in a let-statement, this + /// is *within* the let-statement, rather than outside + /// of it. + /// + /// This is needed because the visibility source scope of locals within + /// a let-statement is weird. + /// + /// The reason is that we want the local to be *within* the let-statement + /// for lint purposes, but we want the local to be *after* the let-statement + /// for names-in-scope purposes. + /// + /// That's it, if we have a let-statement like the one in this + /// function: + /// + /// ``` + /// fn foo(x: &str) { + /// #[allow(unused_mut)] + /// let mut x: u32 = { // <- one unused mut + /// let mut y: u32 = x.parse().unwrap(); + /// y + 2 + /// }; + /// drop(x); + /// } + /// ``` + /// + /// Then, from a lint point of view, the declaration of `x: u32` + /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the + /// lint scopes are the same as the AST/HIR nesting. + /// + /// However, from a name lookup point of view, the scopes look more like + /// as if the let-statements were `match` expressions: + /// + /// ``` + /// fn foo(x: &str) { + /// match { + /// match x.parse().unwrap() { + /// y => y + 2 + /// } + /// } { + /// x => drop(x) + /// }; + /// } + /// ``` + /// + /// We care about the name-lookup scopes for debuginfo - if the + /// debuginfo instruction pointer is at the call to `x.parse()`, we + /// want `x` to refer to `x: &str`, but if it is at the call to + /// `drop(x)`, we want it to refer to `x: u32`. + /// + /// To allow both uses to work, we need to have more than a single scope + /// for a local. We have the `source_info.scope` represent the "syntactic" + /// lint scope (with a variable being under its let block) while the + /// `var_debug_info.source_info.scope` represents the "local variable" + /// scope (where the "rest" of a block is under all prior let-statements). + /// + /// The end result looks like this: + /// + /// ```text + /// ROOT SCOPE + /// │{ argument x: &str } + /// │ + /// │ │{ #[allow(unused_mut)] } // This is actually split into 2 scopes + /// │ │ // in practice because I'm lazy. + /// │ │ + /// │ │← x.source_info.scope + /// │ │← `x.parse().unwrap()` + /// │ │ + /// │ │ │← y.source_info.scope + /// │ │ + /// │ │ │{ let y: u32 } + /// │ │ │ + /// │ │ │← y.var_debug_info.source_info.scope + /// │ │ │← `y + 2` + /// │ + /// │ │{ let x: u32 } + /// │ │← x.var_debug_info.source_info.scope + /// │ │← `drop(x)` // This accesses `x: u32`. + /// ``` + pub source_info: SourceInfo, +} + +// `LocalDecl` is used a lot. Make sure it doesn't unintentionally get bigger. +#[cfg(target_arch = "x86_64")] +static_assert_size!(LocalDecl<'_>, 56); + +/// Extra information about a some locals that's used for diagnostics and for +/// classifying variables into local variables, statics, etc, which is needed e.g. +/// for unsafety checking. +/// +/// Not used for non-StaticRef temporaries, the return place, or anonymous +/// function parameters. +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub enum LocalInfo<'tcx> { + /// A user-defined local variable or function parameter + /// + /// The `BindingForm` is solely used for local diagnostics when generating + /// warnings/errors when compiling the current crate, and therefore it need + /// not be visible across crates. + User(ClearCrossCrate<BindingForm<'tcx>>), + /// A temporary created that references the static with the given `DefId`. + StaticRef { def_id: DefId, is_thread_local: bool }, +} + +impl<'tcx> LocalDecl<'tcx> { + /// Returns `true` only if local is a binding that can itself be + /// made mutable via the addition of the `mut` keyword, namely + /// something like the occurrences of `x` in: + /// - `fn foo(x: Type) { ... }`, + /// - `let x = ...`, + /// - or `match ... { C(x) => ... }` + pub fn can_be_made_mutable(&self) -> bool { + match self.local_info { + Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm { + binding_mode: ty::BindingMode::BindByValue(_), + opt_ty_info: _, + opt_match_place: _, + pat_span: _, + })))) => true, + + Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf( + ImplicitSelfKind::Imm, + )))) => true, + + _ => false, + } + } + + /// Returns `true` if local is definitely not a `ref ident` or + /// `ref mut ident` binding. (Such bindings cannot be made into + /// mutable bindings, but the inverse does not necessarily hold). + pub fn is_nonref_binding(&self) -> bool { + match self.local_info { + Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm { + binding_mode: ty::BindingMode::BindByValue(_), + opt_ty_info: _, + opt_match_place: _, + pat_span: _, + })))) => true, + + Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(_)))) => true, + + _ => false, + } + } + + /// Returns `true` if this variable is a named variable or function + /// parameter declared by the user. + #[inline] + pub fn is_user_variable(&self) -> bool { + match self.local_info { + Some(box LocalInfo::User(_)) => true, + _ => false, + } + } + + /// Returns `true` if this is a reference to a variable bound in a `match` + /// expression that is used to access said variable for the guard of the + /// match arm. + pub fn is_ref_for_guard(&self) -> bool { + match self.local_info { + Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard))) => true, + _ => false, + } + } + + /// Returns `Some` if this is a reference to a static item that is used to + /// access that static + pub fn is_ref_to_static(&self) -> bool { + match self.local_info { + Some(box LocalInfo::StaticRef { .. }) => true, + _ => false, + } + } + + /// Returns `Some` if this is a reference to a static item that is used to + /// access that static + pub fn is_ref_to_thread_local(&self) -> bool { + match self.local_info { + Some(box LocalInfo::StaticRef { is_thread_local, .. }) => is_thread_local, + _ => false, + } + } + + /// Returns `true` is the local is from a compiler desugaring, e.g., + /// `__next` from a `for` loop. + #[inline] + pub fn from_compiler_desugaring(&self) -> bool { + self.source_info.span.desugaring_kind().is_some() + } + + /// Creates a new `LocalDecl` for a temporary: mutable, non-internal. + #[inline] + pub fn new(ty: Ty<'tcx>, span: Span) -> Self { + Self::with_source_info(ty, SourceInfo::outermost(span)) + } + + /// Like `LocalDecl::new`, but takes a `SourceInfo` instead of a `Span`. + #[inline] + pub fn with_source_info(ty: Ty<'tcx>, source_info: SourceInfo) -> Self { + LocalDecl { + mutability: Mutability::Mut, + local_info: None, + internal: false, + is_block_tail: None, + ty, + user_ty: None, + source_info, + } + } + + /// Converts `self` into same `LocalDecl` except tagged as internal. + #[inline] + pub fn internal(mut self) -> Self { + self.internal = true; + self + } + + /// Converts `self` into same `LocalDecl` except tagged as immutable. + #[inline] + pub fn immutable(mut self) -> Self { + self.mutability = Mutability::Not; + self + } + + /// Converts `self` into same `LocalDecl` except tagged as internal temporary. + #[inline] + pub fn block_tail(mut self, info: BlockTailInfo) -> Self { + assert!(self.is_block_tail.is_none()); + self.is_block_tail = Some(info); + self + } +} + +/// Debug information pertaining to a user variable. +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct VarDebugInfo<'tcx> { + pub name: Symbol, + + /// Source info of the user variable, including the scope + /// within which the variable is visible (to debuginfo) + /// (see `LocalDecl`'s `source_info` field for more details). + pub source_info: SourceInfo, + + /// Where the data for this user variable is to be found. + /// NOTE(eddyb) There's an unenforced invariant that this `Place` is + /// based on a `Local`, not a `Static`, and contains no indexing. + pub place: Place<'tcx>, +} + +/////////////////////////////////////////////////////////////////////////// +// BasicBlock + +rustc_index::newtype_index! { + pub struct BasicBlock { + derive [HashStable] + DEBUG_FORMAT = "bb{}", + const START_BLOCK = 0, + } +} + +impl BasicBlock { + pub fn start_location(self) -> Location { + Location { block: self, statement_index: 0 } + } +} + +/////////////////////////////////////////////////////////////////////////// +// BasicBlockData and Terminator + +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct BasicBlockData<'tcx> { + /// List of statements in this block. + pub statements: Vec<Statement<'tcx>>, + + /// Terminator for this block. + /// + /// N.B., this should generally ONLY be `None` during construction. + /// Therefore, you should generally access it via the + /// `terminator()` or `terminator_mut()` methods. The only + /// exception is that certain passes, such as `simplify_cfg`, swap + /// out the terminator temporarily with `None` while they continue + /// to recurse over the set of basic blocks. + pub terminator: Option<Terminator<'tcx>>, + + /// If true, this block lies on an unwind path. This is used + /// during codegen where distinct kinds of basic blocks may be + /// generated (particularly for MSVC cleanup). Unwind blocks must + /// only branch to other unwind blocks. + pub is_cleanup: bool, +} + +/// Information about an assertion failure. +#[derive(Clone, TyEncodable, TyDecodable, HashStable, PartialEq)] +pub enum AssertKind<O> { + BoundsCheck { len: O, index: O }, + Overflow(BinOp, O, O), + OverflowNeg(O), + DivisionByZero(O), + RemainderByZero(O), + ResumedAfterReturn(GeneratorKind), + ResumedAfterPanic(GeneratorKind), +} + +#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub enum InlineAsmOperand<'tcx> { + In { + reg: InlineAsmRegOrRegClass, + value: Operand<'tcx>, + }, + Out { + reg: InlineAsmRegOrRegClass, + late: bool, + place: Option<Place<'tcx>>, + }, + InOut { + reg: InlineAsmRegOrRegClass, + late: bool, + in_value: Operand<'tcx>, + out_place: Option<Place<'tcx>>, + }, + Const { + value: Operand<'tcx>, + }, + SymFn { + value: Box<Constant<'tcx>>, + }, + SymStatic { + def_id: DefId, + }, +} + +/// Type for MIR `Assert` terminator error messages. +pub type AssertMessage<'tcx> = AssertKind<Operand<'tcx>>; + +pub type Successors<'a> = + iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>; +pub type SuccessorsMut<'a> = + iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>; + +impl<'tcx> BasicBlockData<'tcx> { + pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> { + BasicBlockData { statements: vec![], terminator, is_cleanup: false } + } + + /// Accessor for terminator. + /// + /// Terminator may not be None after construction of the basic block is complete. This accessor + /// provides a convenience way to reach the terminator. + pub fn terminator(&self) -> &Terminator<'tcx> { + self.terminator.as_ref().expect("invalid terminator state") + } + + pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> { + self.terminator.as_mut().expect("invalid terminator state") + } + + pub fn retain_statements<F>(&mut self, mut f: F) + where + F: FnMut(&mut Statement<'_>) -> bool, + { + for s in &mut self.statements { + if !f(s) { + s.make_nop(); + } + } + } + + pub fn expand_statements<F, I>(&mut self, mut f: F) + where + F: FnMut(&mut Statement<'tcx>) -> Option<I>, + I: iter::TrustedLen<Item = Statement<'tcx>>, + { + // Gather all the iterators we'll need to splice in, and their positions. + let mut splices: Vec<(usize, I)> = vec![]; + let mut extra_stmts = 0; + for (i, s) in self.statements.iter_mut().enumerate() { + if let Some(mut new_stmts) = f(s) { + if let Some(first) = new_stmts.next() { + // We can already store the first new statement. + *s = first; + + // Save the other statements for optimized splicing. + let remaining = new_stmts.size_hint().0; + if remaining > 0 { + splices.push((i + 1 + extra_stmts, new_stmts)); + extra_stmts += remaining; + } + } else { + s.make_nop(); + } + } + } + + // Splice in the new statements, from the end of the block. + // FIXME(eddyb) This could be more efficient with a "gap buffer" + // where a range of elements ("gap") is left uninitialized, with + // splicing adding new elements to the end of that gap and moving + // existing elements from before the gap to the end of the gap. + // For now, this is safe code, emulating a gap but initializing it. + let mut gap = self.statements.len()..self.statements.len() + extra_stmts; + self.statements.resize( + gap.end, + Statement { source_info: SourceInfo::outermost(DUMMY_SP), kind: StatementKind::Nop }, + ); + for (splice_start, new_stmts) in splices.into_iter().rev() { + let splice_end = splice_start + new_stmts.size_hint().0; + while gap.end > splice_end { + gap.start -= 1; + gap.end -= 1; + self.statements.swap(gap.start, gap.end); + } + self.statements.splice(splice_start..splice_end, new_stmts); + gap.end = splice_start; + } + } + + pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> { + if index < self.statements.len() { &self.statements[index] } else { &self.terminator } + } +} + +impl<O> AssertKind<O> { + /// Getting a description does not require `O` to be printable, and does not + /// require allocation. + /// The caller is expected to handle `BoundsCheck` separately. + pub fn description(&self) -> &'static str { + use AssertKind::*; + match self { + Overflow(BinOp::Add, _, _) => "attempt to add with overflow", + Overflow(BinOp::Sub, _, _) => "attempt to subtract with overflow", + Overflow(BinOp::Mul, _, _) => "attempt to multiply with overflow", + Overflow(BinOp::Div, _, _) => "attempt to divide with overflow", + Overflow(BinOp::Rem, _, _) => "attempt to calculate the remainder with overflow", + OverflowNeg(_) => "attempt to negate with overflow", + Overflow(BinOp::Shr, _, _) => "attempt to shift right with overflow", + Overflow(BinOp::Shl, _, _) => "attempt to shift left with overflow", + Overflow(op, _, _) => bug!("{:?} cannot overflow", op), + DivisionByZero(_) => "attempt to divide by zero", + RemainderByZero(_) => "attempt to calculate the remainder with a divisor of zero", + ResumedAfterReturn(GeneratorKind::Gen) => "generator resumed after completion", + ResumedAfterReturn(GeneratorKind::Async(_)) => "`async fn` resumed after completion", + ResumedAfterPanic(GeneratorKind::Gen) => "generator resumed after panicking", + ResumedAfterPanic(GeneratorKind::Async(_)) => "`async fn` resumed after panicking", + BoundsCheck { .. } => bug!("Unexpected AssertKind"), + } + } + + /// Format the message arguments for the `assert(cond, msg..)` terminator in MIR printing. + fn fmt_assert_args<W: Write>(&self, f: &mut W) -> fmt::Result + where + O: Debug, + { + use AssertKind::*; + match self { + BoundsCheck { ref len, ref index } => write!( + f, + "\"index out of bounds: the len is {{}} but the index is {{}}\", {:?}, {:?}", + len, index + ), + + OverflowNeg(op) => { + write!(f, "\"attempt to negate {{}} which would overflow\", {:?}", op) + } + DivisionByZero(op) => write!(f, "\"attempt to divide {{}} by zero\", {:?}", op), + RemainderByZero(op) => write!( + f, + "\"attempt to calculate the remainder of {{}} with a divisor of zero\", {:?}", + op + ), + Overflow(BinOp::Add, l, r) => write!( + f, + "\"attempt to compute `{{}} + {{}}` which would overflow\", {:?}, {:?}", + l, r + ), + Overflow(BinOp::Sub, l, r) => write!( + f, + "\"attempt to compute `{{}} - {{}}` which would overflow\", {:?}, {:?}", + l, r + ), + Overflow(BinOp::Mul, l, r) => write!( + f, + "\"attempt to compute `{{}} * {{}}` which would overflow\", {:?}, {:?}", + l, r + ), + Overflow(BinOp::Div, l, r) => write!( + f, + "\"attempt to compute `{{}} / {{}}` which would overflow\", {:?}, {:?}", + l, r + ), + Overflow(BinOp::Rem, l, r) => write!( + f, + "\"attempt to compute the remainder of `{{}} % {{}}` which would overflow\", {:?}, {:?}", + l, r + ), + Overflow(BinOp::Shr, _, r) => { + write!(f, "\"attempt to shift right by {{}} which would overflow\", {:?}", r) + } + Overflow(BinOp::Shl, _, r) => { + write!(f, "\"attempt to shift left by {{}} which would overflow\", {:?}", r) + } + _ => write!(f, "\"{}\"", self.description()), + } + } +} + +impl<O: fmt::Debug> fmt::Debug for AssertKind<O> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use AssertKind::*; + match self { + BoundsCheck { ref len, ref index } => { + write!(f, "index out of bounds: the len is {:?} but the index is {:?}", len, index) + } + OverflowNeg(op) => write!(f, "attempt to negate {:#?} which would overflow", op), + DivisionByZero(op) => write!(f, "attempt to divide {:#?} by zero", op), + RemainderByZero(op) => { + write!(f, "attempt to calculate the remainder of {:#?} with a divisor of zero", op) + } + Overflow(BinOp::Add, l, r) => { + write!(f, "attempt to compute `{:#?} + {:#?}` which would overflow", l, r) + } + Overflow(BinOp::Sub, l, r) => { + write!(f, "attempt to compute `{:#?} - {:#?}` which would overflow", l, r) + } + Overflow(BinOp::Mul, l, r) => { + write!(f, "attempt to compute `{:#?} * {:#?}` which would overflow", l, r) + } + Overflow(BinOp::Div, l, r) => { + write!(f, "attempt to compute `{:#?} / {:#?}` which would overflow", l, r) + } + Overflow(BinOp::Rem, l, r) => write!( + f, + "attempt to compute the remainder of `{:#?} % {:#?}` which would overflow", + l, r + ), + Overflow(BinOp::Shr, _, r) => { + write!(f, "attempt to shift right by {:#?} which would overflow", r) + } + Overflow(BinOp::Shl, _, r) => { + write!(f, "attempt to shift left by {:#?} which would overflow", r) + } + _ => write!(f, "{}", self.description()), + } + } +} + +/////////////////////////////////////////////////////////////////////////// +// Statements + +#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct Statement<'tcx> { + pub source_info: SourceInfo, + pub kind: StatementKind<'tcx>, +} + +// `Statement` is used a lot. Make sure it doesn't unintentionally get bigger. +#[cfg(target_arch = "x86_64")] +static_assert_size!(Statement<'_>, 32); + +impl Statement<'_> { + /// Changes a statement to a nop. This is both faster than deleting instructions and avoids + /// invalidating statement indices in `Location`s. + pub fn make_nop(&mut self) { + self.kind = StatementKind::Nop + } + + /// Changes a statement to a nop and returns the original statement. + pub fn replace_nop(&mut self) -> Self { + Statement { + source_info: self.source_info, + kind: mem::replace(&mut self.kind, StatementKind::Nop), + } + } +} + +#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub enum StatementKind<'tcx> { + /// Write the RHS Rvalue to the LHS Place. + Assign(Box<(Place<'tcx>, Rvalue<'tcx>)>), + + /// This represents all the reading that a pattern match may do + /// (e.g., inspecting constants and discriminant values), and the + /// kind of pattern it comes from. This is in order to adapt potential + /// error messages to these specific patterns. + /// + /// Note that this also is emitted for regular `let` bindings to ensure that locals that are + /// never accessed still get some sanity checks for, e.g., `let x: ! = ..;` + FakeRead(FakeReadCause, Box<Place<'tcx>>), + + /// Write the discriminant for a variant to the enum Place. + SetDiscriminant { place: Box<Place<'tcx>>, variant_index: VariantIdx }, + + /// Start a live range for the storage of the local. + StorageLive(Local), + + /// End the current live range for the storage of the local. + StorageDead(Local), + + /// Executes a piece of inline Assembly. Stored in a Box to keep the size + /// of `StatementKind` low. + LlvmInlineAsm(Box<LlvmInlineAsm<'tcx>>), + + /// Retag references in the given place, ensuring they got fresh tags. This is + /// part of the Stacked Borrows model. These statements are currently only interpreted + /// by miri and only generated when "-Z mir-emit-retag" is passed. + /// See <https://internals.rust-lang.org/t/stacked-borrows-an-aliasing-model-for-rust/8153/> + /// for more details. + Retag(RetagKind, Box<Place<'tcx>>), + + /// Encodes a user's type ascription. These need to be preserved + /// intact so that NLL can respect them. For example: + /// + /// let a: T = y; + /// + /// The effect of this annotation is to relate the type `T_y` of the place `y` + /// to the user-given type `T`. The effect depends on the specified variance: + /// + /// - `Covariant` -- requires that `T_y <: T` + /// - `Contravariant` -- requires that `T_y :> T` + /// - `Invariant` -- requires that `T_y == T` + /// - `Bivariant` -- no effect + AscribeUserType(Box<(Place<'tcx>, UserTypeProjection)>, ty::Variance), + + /// Marks the start of a "coverage region", injected with '-Zinstrument-coverage'. A + /// `CoverageInfo` statement carries metadata about the coverage region, used to inject a coverage + /// map into the binary. The `Counter` kind also generates executable code, to increment a + /// counter varible at runtime, each time the code region is executed. + Coverage(Box<Coverage>), + + /// No-op. Useful for deleting instructions without affecting statement indices. + Nop, +} + +impl<'tcx> StatementKind<'tcx> { + pub fn as_assign_mut(&mut self) -> Option<&mut Box<(Place<'tcx>, Rvalue<'tcx>)>> { + match self { + StatementKind::Assign(x) => Some(x), + _ => None, + } + } +} + +/// Describes what kind of retag is to be performed. +#[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, PartialEq, Eq, HashStable)] +pub enum RetagKind { + /// The initial retag when entering a function. + FnEntry, + /// Retag preparing for a two-phase borrow. + TwoPhase, + /// Retagging raw pointers. + Raw, + /// A "normal" retag. + Default, +} + +/// The `FakeReadCause` describes the type of pattern why a FakeRead statement exists. +#[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, HashStable, PartialEq)] +pub enum FakeReadCause { + /// Inject a fake read of the borrowed input at the end of each guards + /// code. + /// + /// This should ensure that you cannot change the variant for an enum while + /// you are in the midst of matching on it. + ForMatchGuard, + + /// `let x: !; match x {}` doesn't generate any read of x so we need to + /// generate a read of x to check that it is initialized and safe. + ForMatchedPlace, + + /// A fake read of the RefWithinGuard version of a bind-by-value variable + /// in a match guard to ensure that it's value hasn't change by the time + /// we create the OutsideGuard version. + ForGuardBinding, + + /// Officially, the semantics of + /// + /// `let pattern = <expr>;` + /// + /// is that `<expr>` is evaluated into a temporary and then this temporary is + /// into the pattern. + /// + /// However, if we see the simple pattern `let var = <expr>`, we optimize this to + /// evaluate `<expr>` directly into the variable `var`. This is mostly unobservable, + /// but in some cases it can affect the borrow checker, as in #53695. + /// Therefore, we insert a "fake read" here to ensure that we get + /// appropriate errors. + ForLet, + + /// If we have an index expression like + /// + /// (*x)[1][{ x = y; 4}] + /// + /// then the first bounds check is invalidated when we evaluate the second + /// index expression. Thus we create a fake borrow of `x` across the second + /// indexer, which will cause a borrow check error. + ForIndex, +} + +#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct LlvmInlineAsm<'tcx> { + pub asm: hir::LlvmInlineAsmInner, + pub outputs: Box<[Place<'tcx>]>, + pub inputs: Box<[(Span, Operand<'tcx>)]>, +} + +impl Debug for Statement<'_> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + use self::StatementKind::*; + match self.kind { + Assign(box (ref place, ref rv)) => write!(fmt, "{:?} = {:?}", place, rv), + FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place), + Retag(ref kind, ref place) => write!( + fmt, + "Retag({}{:?})", + match kind { + RetagKind::FnEntry => "[fn entry] ", + RetagKind::TwoPhase => "[2phase] ", + RetagKind::Raw => "[raw] ", + RetagKind::Default => "", + }, + place, + ), + StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place), + StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place), + SetDiscriminant { ref place, variant_index } => { + write!(fmt, "discriminant({:?}) = {:?}", place, variant_index) + } + LlvmInlineAsm(ref asm) => { + write!(fmt, "llvm_asm!({:?} : {:?} : {:?})", asm.asm, asm.outputs, asm.inputs) + } + AscribeUserType(box (ref place, ref c_ty), ref variance) => { + write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty) + } + Coverage(box ref coverage) => write!(fmt, "{:?}", coverage), + Nop => write!(fmt, "nop"), + } + } +} + +#[derive(Clone, Debug, PartialEq, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct Coverage { + pub kind: CoverageKind, + pub code_region: CodeRegion, +} + +/////////////////////////////////////////////////////////////////////////// +// Places + +/// A path to a value; something that can be evaluated without +/// changing or disturbing program state. +#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)] +pub struct Place<'tcx> { + pub local: Local, + + /// projection out of a place (access a field, deref a pointer, etc) + pub projection: &'tcx List<PlaceElem<'tcx>>, +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] +#[derive(TyEncodable, TyDecodable, HashStable)] +pub enum ProjectionElem<V, T> { + Deref, + Field(Field, T), + Index(V), + + /// These indices are generated by slice patterns. Easiest to explain + /// by example: + /// + /// ``` + /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false }, + /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false }, + /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true }, + /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true }, + /// ``` + ConstantIndex { + /// index or -index (in Python terms), depending on from_end + offset: u64, + /// The thing being indexed must be at least this long. For arrays this + /// is always the exact length. + min_length: u64, + /// Counting backwards from end? This is always false when indexing an + /// array. + from_end: bool, + }, + + /// These indices are generated by slice patterns. + /// + /// If `from_end` is true `slice[from..slice.len() - to]`. + /// Otherwise `array[from..to]`. + Subslice { + from: u64, + to: u64, + /// Whether `to` counts from the start or end of the array/slice. + /// For `PlaceElem`s this is `true` if and only if the base is a slice. + /// For `ProjectionKind`, this can also be `true` for arrays. + from_end: bool, + }, + + /// "Downcast" to a variant of an ADT. Currently, we only introduce + /// this for ADTs with more than one variant. It may be better to + /// just introduce it always, or always for enums. + /// + /// The included Symbol is the name of the variant, used for printing MIR. + Downcast(Option<Symbol>, VariantIdx), +} + +impl<V, T> ProjectionElem<V, T> { + /// Returns `true` if the target of this projection may refer to a different region of memory + /// than the base. + fn is_indirect(&self) -> bool { + match self { + Self::Deref => true, + + Self::Field(_, _) + | Self::Index(_) + | Self::ConstantIndex { .. } + | Self::Subslice { .. } + | Self::Downcast(_, _) => false, + } + } +} + +/// Alias for projections as they appear in places, where the base is a place +/// and the index is a local. +pub type PlaceElem<'tcx> = ProjectionElem<Local, Ty<'tcx>>; + +// At least on 64 bit systems, `PlaceElem` should not be larger than two pointers. +#[cfg(target_arch = "x86_64")] +static_assert_size!(PlaceElem<'_>, 24); + +/// Alias for projections as they appear in `UserTypeProjection`, where we +/// need neither the `V` parameter for `Index` nor the `T` for `Field`. +pub type ProjectionKind = ProjectionElem<(), ()>; + +rustc_index::newtype_index! { + pub struct Field { + derive [HashStable] + DEBUG_FORMAT = "field[{}]" + } +} + +#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] +pub struct PlaceRef<'tcx> { + pub local: Local, + pub projection: &'tcx [PlaceElem<'tcx>], +} + +impl<'tcx> Place<'tcx> { + // FIXME change this to a const fn by also making List::empty a const fn. + pub fn return_place() -> Place<'tcx> { + Place { local: RETURN_PLACE, projection: List::empty() } + } + + /// Returns `true` if this `Place` contains a `Deref` projection. + /// + /// If `Place::is_indirect` returns false, the caller knows that the `Place` refers to the + /// same region of memory as its base. + pub fn is_indirect(&self) -> bool { + self.projection.iter().any(|elem| elem.is_indirect()) + } + + /// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or + /// a single deref of a local. + // + // FIXME: can we safely swap the semantics of `fn base_local` below in here instead? + pub fn local_or_deref_local(&self) -> Option<Local> { + match self.as_ref() { + PlaceRef { local, projection: [] } + | PlaceRef { local, projection: [ProjectionElem::Deref] } => Some(local), + _ => None, + } + } + + /// If this place represents a local variable like `_X` with no + /// projections, return `Some(_X)`. + pub fn as_local(&self) -> Option<Local> { + self.as_ref().as_local() + } + + pub fn as_ref(&self) -> PlaceRef<'tcx> { + PlaceRef { local: self.local, projection: &self.projection } + } +} + +impl From<Local> for Place<'_> { + fn from(local: Local) -> Self { + Place { local, projection: List::empty() } + } +} + +impl<'tcx> PlaceRef<'tcx> { + /// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or + /// a single deref of a local. + // + // FIXME: can we safely swap the semantics of `fn base_local` below in here instead? + pub fn local_or_deref_local(&self) -> Option<Local> { + match *self { + PlaceRef { local, projection: [] } + | PlaceRef { local, projection: [ProjectionElem::Deref] } => Some(local), + _ => None, + } + } + + /// If this place represents a local variable like `_X` with no + /// projections, return `Some(_X)`. + pub fn as_local(&self) -> Option<Local> { + match *self { + PlaceRef { local, projection: [] } => Some(local), + _ => None, + } + } +} + +impl Debug for Place<'_> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + for elem in self.projection.iter().rev() { + match elem { + ProjectionElem::Downcast(_, _) | ProjectionElem::Field(_, _) => { + write!(fmt, "(").unwrap(); + } + ProjectionElem::Deref => { + write!(fmt, "(*").unwrap(); + } + ProjectionElem::Index(_) + | ProjectionElem::ConstantIndex { .. } + | ProjectionElem::Subslice { .. } => {} + } + } + + write!(fmt, "{:?}", self.local)?; + + for elem in self.projection.iter() { + match elem { + ProjectionElem::Downcast(Some(name), _index) => { + write!(fmt, " as {})", name)?; + } + ProjectionElem::Downcast(None, index) => { + write!(fmt, " as variant#{:?})", index)?; + } + ProjectionElem::Deref => { + write!(fmt, ")")?; + } + ProjectionElem::Field(field, ty) => { + write!(fmt, ".{:?}: {:?})", field.index(), ty)?; + } + ProjectionElem::Index(ref index) => { + write!(fmt, "[{:?}]", index)?; + } + ProjectionElem::ConstantIndex { offset, min_length, from_end: false } => { + write!(fmt, "[{:?} of {:?}]", offset, min_length)?; + } + ProjectionElem::ConstantIndex { offset, min_length, from_end: true } => { + write!(fmt, "[-{:?} of {:?}]", offset, min_length)?; + } + ProjectionElem::Subslice { from, to, from_end: true } if to == 0 => { + write!(fmt, "[{:?}:]", from)?; + } + ProjectionElem::Subslice { from, to, from_end: true } if from == 0 => { + write!(fmt, "[:-{:?}]", to)?; + } + ProjectionElem::Subslice { from, to, from_end: true } => { + write!(fmt, "[{:?}:-{:?}]", from, to)?; + } + ProjectionElem::Subslice { from, to, from_end: false } => { + write!(fmt, "[{:?}..{:?}]", from, to)?; + } + } + } + + Ok(()) + } +} + +/////////////////////////////////////////////////////////////////////////// +// Scopes + +rustc_index::newtype_index! { + pub struct SourceScope { + derive [HashStable] + DEBUG_FORMAT = "scope[{}]", + const OUTERMOST_SOURCE_SCOPE = 0, + } +} + +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct SourceScopeData { + pub span: Span, + pub parent_scope: Option<SourceScope>, + + /// Crate-local information for this source scope, that can't (and + /// needn't) be tracked across crates. + pub local_data: ClearCrossCrate<SourceScopeLocalData>, +} + +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct SourceScopeLocalData { + /// An `HirId` with lint levels equivalent to this scope's lint levels. + pub lint_root: hir::HirId, + /// The unsafe block that contains this node. + pub safety: Safety, +} + +/////////////////////////////////////////////////////////////////////////// +// Operands + +/// These are values that can appear inside an rvalue. They are intentionally +/// limited to prevent rvalues from being nested in one another. +#[derive(Clone, PartialEq, TyEncodable, TyDecodable, HashStable)] +pub enum Operand<'tcx> { + /// Copy: The value must be available for use afterwards. + /// + /// This implies that the type of the place must be `Copy`; this is true + /// by construction during build, but also checked by the MIR type checker. + Copy(Place<'tcx>), + + /// Move: The value (including old borrows of it) will not be used again. + /// + /// Safe for values of all types (modulo future developments towards `?Move`). + /// Correct usage patterns are enforced by the borrow checker for safe code. + /// `Copy` may be converted to `Move` to enable "last-use" optimizations. + Move(Place<'tcx>), + + /// Synthesizes a constant value. + Constant(Box<Constant<'tcx>>), +} + +impl<'tcx> Debug for Operand<'tcx> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + use self::Operand::*; + match *self { + Constant(ref a) => write!(fmt, "{:?}", a), + Copy(ref place) => write!(fmt, "{:?}", place), + Move(ref place) => write!(fmt, "move {:?}", place), + } + } +} + +impl<'tcx> Operand<'tcx> { + /// Convenience helper to make a constant that refers to the fn + /// with given `DefId` and substs. Since this is used to synthesize + /// MIR, assumes `user_ty` is None. + pub fn function_handle( + tcx: TyCtxt<'tcx>, + def_id: DefId, + substs: SubstsRef<'tcx>, + span: Span, + ) -> Self { + let ty = tcx.type_of(def_id).subst(tcx, substs); + Operand::Constant(box Constant { + span, + user_ty: None, + literal: ty::Const::zero_sized(tcx, ty), + }) + } + + pub fn is_move(&self) -> bool { + matches!(self, Operand::Move(..)) + } + + /// Convenience helper to make a literal-like constant from a given scalar value. + /// Since this is used to synthesize MIR, assumes `user_ty` is None. + pub fn const_from_scalar( + tcx: TyCtxt<'tcx>, + ty: Ty<'tcx>, + val: Scalar, + span: Span, + ) -> Operand<'tcx> { + debug_assert!({ + let param_env_and_ty = ty::ParamEnv::empty().and(ty); + let type_size = tcx + .layout_of(param_env_and_ty) + .unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e)) + .size; + let scalar_size = abi::Size::from_bytes(match val { + Scalar::Raw { size, .. } => size, + _ => panic!("Invalid scalar type {:?}", val), + }); + scalar_size == type_size + }); + Operand::Constant(box Constant { + span, + user_ty: None, + literal: ty::Const::from_scalar(tcx, val, ty), + }) + } + + /// Convenience helper to make a `Scalar` from the given `Operand`, assuming that `Operand` + /// wraps a constant literal value. Panics if this is not the case. + pub fn scalar_from_const(operand: &Operand<'tcx>) -> Scalar { + match operand { + Operand::Constant(constant) => match constant.literal.val.try_to_scalar() { + Some(scalar) => scalar, + _ => panic!("{:?}: Scalar value expected", constant.literal.val), + }, + _ => panic!("{:?}: Constant expected", operand), + } + } + + /// Convenience helper to make a literal-like constant from a given `&str` slice. + /// Since this is used to synthesize MIR, assumes `user_ty` is None. + pub fn const_from_str(tcx: TyCtxt<'tcx>, val: &str, span: Span) -> Operand<'tcx> { + let tcx = tcx; + let allocation = Allocation::from_byte_aligned_bytes(val.as_bytes()); + let allocation = tcx.intern_const_alloc(allocation); + let const_val = ConstValue::Slice { data: allocation, start: 0, end: val.len() }; + let ty = tcx.mk_imm_ref(tcx.lifetimes.re_erased, tcx.types.str_); + Operand::Constant(box Constant { + span, + user_ty: None, + literal: ty::Const::from_value(tcx, const_val, ty), + }) + } + + /// Convenience helper to make a `ConstValue` from the given `Operand`, assuming that `Operand` + /// wraps a constant value (such as a `&str` slice). Panics if this is not the case. + pub fn value_from_const(operand: &Operand<'tcx>) -> ConstValue<'tcx> { + match operand { + Operand::Constant(constant) => match constant.literal.val.try_to_value() { + Some(const_value) => const_value, + _ => panic!("{:?}: ConstValue expected", constant.literal.val), + }, + _ => panic!("{:?}: Constant expected", operand), + } + } + + pub fn to_copy(&self) -> Self { + match *self { + Operand::Copy(_) | Operand::Constant(_) => self.clone(), + Operand::Move(place) => Operand::Copy(place), + } + } + + /// Returns the `Place` that is the target of this `Operand`, or `None` if this `Operand` is a + /// constant. + pub fn place(&self) -> Option<Place<'tcx>> { + match self { + Operand::Copy(place) | Operand::Move(place) => Some(*place), + Operand::Constant(_) => None, + } + } +} + +/////////////////////////////////////////////////////////////////////////// +/// Rvalues + +#[derive(Clone, TyEncodable, TyDecodable, HashStable, PartialEq)] +pub enum Rvalue<'tcx> { + /// x (either a move or copy, depending on type of x) + Use(Operand<'tcx>), + + /// [x; 32] + Repeat(Operand<'tcx>, &'tcx ty::Const<'tcx>), + + /// &x or &mut x + Ref(Region<'tcx>, BorrowKind, Place<'tcx>), + + /// Accessing a thread local static. This is inherently a runtime operation, even if llvm + /// treats it as an access to a static. This `Rvalue` yields a reference to the thread local + /// static. + ThreadLocalRef(DefId), + + /// Create a raw pointer to the given place + /// Can be generated by raw address of expressions (`&raw const x`), + /// or when casting a reference to a raw pointer. + AddressOf(Mutability, Place<'tcx>), + + /// length of a `[X]` or `[X;n]` value + Len(Place<'tcx>), + + Cast(CastKind, Operand<'tcx>, Ty<'tcx>), + + BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>), + CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>), + + NullaryOp(NullOp, Ty<'tcx>), + UnaryOp(UnOp, Operand<'tcx>), + + /// Read the discriminant of an ADT. + /// + /// Undefined (i.e., no effort is made to make it defined, but there’s no reason why it cannot + /// be defined to return, say, a 0) if ADT is not an enum. + Discriminant(Place<'tcx>), + + /// Creates an aggregate value, like a tuple or struct. This is + /// only needed because we want to distinguish `dest = Foo { x: + /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case + /// that `Foo` has a destructor. These rvalues can be optimized + /// away after type-checking and before lowering. + Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>), +} + +#[derive(Clone, Copy, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] +pub enum CastKind { + Misc, + Pointer(PointerCast), +} + +#[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] +pub enum AggregateKind<'tcx> { + /// The type is of the element + Array(Ty<'tcx>), + Tuple, + + /// The second field is the variant index. It's equal to 0 for struct + /// and union expressions. The fourth field is + /// active field number and is present only for union expressions + /// -- e.g., for a union expression `SomeUnion { c: .. }`, the + /// active field index would identity the field `c` + Adt(&'tcx AdtDef, VariantIdx, SubstsRef<'tcx>, Option<UserTypeAnnotationIndex>, Option<usize>), + + Closure(DefId, SubstsRef<'tcx>), + Generator(DefId, SubstsRef<'tcx>, hir::Movability), +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] +pub enum BinOp { + /// The `+` operator (addition) + Add, + /// The `-` operator (subtraction) + Sub, + /// The `*` operator (multiplication) + Mul, + /// The `/` operator (division) + Div, + /// The `%` operator (modulus) + Rem, + /// The `^` operator (bitwise xor) + BitXor, + /// The `&` operator (bitwise and) + BitAnd, + /// The `|` operator (bitwise or) + BitOr, + /// The `<<` operator (shift left) + Shl, + /// The `>>` operator (shift right) + Shr, + /// The `==` operator (equality) + Eq, + /// The `<` operator (less than) + Lt, + /// The `<=` operator (less than or equal to) + Le, + /// The `!=` operator (not equal to) + Ne, + /// The `>=` operator (greater than or equal to) + Ge, + /// The `>` operator (greater than) + Gt, + /// The `ptr.offset` operator + Offset, +} + +impl BinOp { + pub fn is_checkable(self) -> bool { + use self::BinOp::*; + match self { + Add | Sub | Mul | Shl | Shr => true, + _ => false, + } + } +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] +pub enum NullOp { + /// Returns the size of a value of that type + SizeOf, + /// Creates a new uninitialized box for a value of that type + Box, +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] +pub enum UnOp { + /// The `!` operator for logical inversion + Not, + /// The `-` operator for negation + Neg, +} + +impl<'tcx> Debug for Rvalue<'tcx> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + use self::Rvalue::*; + + match *self { + Use(ref place) => write!(fmt, "{:?}", place), + Repeat(ref a, ref b) => { + write!(fmt, "[{:?}; ", a)?; + pretty_print_const(b, fmt, false)?; + write!(fmt, "]") + } + Len(ref a) => write!(fmt, "Len({:?})", a), + Cast(ref kind, ref place, ref ty) => { + write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind) + } + BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b), + CheckedBinaryOp(ref op, ref a, ref b) => { + write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b) + } + UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a), + Discriminant(ref place) => write!(fmt, "discriminant({:?})", place), + NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t), + ThreadLocalRef(did) => ty::tls::with(|tcx| { + let muta = tcx.static_mutability(did).unwrap().prefix_str(); + write!(fmt, "&/*tls*/ {}{}", muta, tcx.def_path_str(did)) + }), + Ref(region, borrow_kind, ref place) => { + let kind_str = match borrow_kind { + BorrowKind::Shared => "", + BorrowKind::Shallow => "shallow ", + BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ", + }; + + // When printing regions, add trailing space if necessary. + let print_region = ty::tls::with(|tcx| { + tcx.sess.verbose() || tcx.sess.opts.debugging_opts.identify_regions + }); + let region = if print_region { + let mut region = region.to_string(); + if !region.is_empty() { + region.push(' '); + } + region + } else { + // Do not even print 'static + String::new() + }; + write!(fmt, "&{}{}{:?}", region, kind_str, place) + } + + AddressOf(mutability, ref place) => { + let kind_str = match mutability { + Mutability::Mut => "mut", + Mutability::Not => "const", + }; + + write!(fmt, "&raw {} {:?}", kind_str, place) + } + + Aggregate(ref kind, ref places) => { + let fmt_tuple = |fmt: &mut Formatter<'_>, name: &str| { + let mut tuple_fmt = fmt.debug_tuple(name); + for place in places { + tuple_fmt.field(place); + } + tuple_fmt.finish() + }; + + match **kind { + AggregateKind::Array(_) => write!(fmt, "{:?}", places), + + AggregateKind::Tuple => { + if places.is_empty() { + write!(fmt, "()") + } else { + fmt_tuple(fmt, "") + } + } + + AggregateKind::Adt(adt_def, variant, substs, _user_ty, _) => { + let variant_def = &adt_def.variants[variant]; + + let name = ty::tls::with(|tcx| { + let mut name = String::new(); + let substs = tcx.lift(&substs).expect("could not lift for printing"); + FmtPrinter::new(tcx, &mut name, Namespace::ValueNS) + .print_def_path(variant_def.def_id, substs)?; + Ok(name) + })?; + + match variant_def.ctor_kind { + CtorKind::Const => fmt.write_str(&name), + CtorKind::Fn => fmt_tuple(fmt, &name), + CtorKind::Fictive => { + let mut struct_fmt = fmt.debug_struct(&name); + for (field, place) in variant_def.fields.iter().zip(places) { + struct_fmt.field(&field.ident.as_str(), place); + } + struct_fmt.finish() + } + } + } + + AggregateKind::Closure(def_id, substs) => ty::tls::with(|tcx| { + if let Some(def_id) = def_id.as_local() { + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); + let name = if tcx.sess.opts.debugging_opts.span_free_formats { + let substs = tcx.lift(&substs).unwrap(); + format!( + "[closure@{}]", + tcx.def_path_str_with_substs(def_id.to_def_id(), substs), + ) + } else { + let span = tcx.hir().span(hir_id); + format!("[closure@{}]", tcx.sess.source_map().span_to_string(span)) + }; + let mut struct_fmt = fmt.debug_struct(&name); + + if let Some(upvars) = tcx.upvars_mentioned(def_id) { + for (&var_id, place) in upvars.keys().zip(places) { + let var_name = tcx.hir().name(var_id); + struct_fmt.field(&var_name.as_str(), place); + } + } + + struct_fmt.finish() + } else { + write!(fmt, "[closure]") + } + }), + + AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| { + if let Some(def_id) = def_id.as_local() { + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); + let name = format!("[generator@{:?}]", tcx.hir().span(hir_id)); + let mut struct_fmt = fmt.debug_struct(&name); + + if let Some(upvars) = tcx.upvars_mentioned(def_id) { + for (&var_id, place) in upvars.keys().zip(places) { + let var_name = tcx.hir().name(var_id); + struct_fmt.field(&var_name.as_str(), place); + } + } + + struct_fmt.finish() + } else { + write!(fmt, "[generator]") + } + }), + } + } + } + } +} + +/////////////////////////////////////////////////////////////////////////// +/// Constants +/// +/// Two constants are equal if they are the same constant. Note that +/// this does not necessarily mean that they are "==" in Rust -- in +/// particular one must be wary of `NaN`! + +#[derive(Clone, Copy, PartialEq, TyEncodable, TyDecodable, HashStable)] +pub struct Constant<'tcx> { + pub span: Span, + + /// Optional user-given type: for something like + /// `collect::<Vec<_>>`, this would be present and would + /// indicate that `Vec<_>` was explicitly specified. + /// + /// Needed for NLL to impose user-given type constraints. + pub user_ty: Option<UserTypeAnnotationIndex>, + + pub literal: &'tcx ty::Const<'tcx>, +} + +impl Constant<'tcx> { + pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> { + match self.literal.val.try_to_scalar() { + Some(Scalar::Ptr(ptr)) => match tcx.global_alloc(ptr.alloc_id) { + GlobalAlloc::Static(def_id) => { + assert!(!tcx.is_thread_local_static(def_id)); + Some(def_id) + } + _ => None, + }, + _ => None, + } + } +} + +/// A collection of projections into user types. +/// +/// They are projections because a binding can occur a part of a +/// parent pattern that has been ascribed a type. +/// +/// Its a collection because there can be multiple type ascriptions on +/// the path from the root of the pattern down to the binding itself. +/// +/// An example: +/// +/// ```rust +/// struct S<'a>((i32, &'a str), String); +/// let S((_, w): (i32, &'static str), _): S = ...; +/// // ------ ^^^^^^^^^^^^^^^^^^^ (1) +/// // --------------------------------- ^ (2) +/// ``` +/// +/// The highlights labelled `(1)` show the subpattern `(_, w)` being +/// ascribed the type `(i32, &'static str)`. +/// +/// The highlights labelled `(2)` show the whole pattern being +/// ascribed the type `S`. +/// +/// In this example, when we descend to `w`, we will have built up the +/// following two projected types: +/// +/// * base: `S`, projection: `(base.0).1` +/// * base: `(i32, &'static str)`, projection: `base.1` +/// +/// The first will lead to the constraint `w: &'1 str` (for some +/// inferred region `'1`). The second will lead to the constraint `w: +/// &'static str`. +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct UserTypeProjections { + pub contents: Vec<(UserTypeProjection, Span)>, +} + +impl<'tcx> UserTypeProjections { + pub fn none() -> Self { + UserTypeProjections { contents: vec![] } + } + + pub fn is_empty(&self) -> bool { + self.contents.is_empty() + } + + pub fn from_projections(projs: impl Iterator<Item = (UserTypeProjection, Span)>) -> Self { + UserTypeProjections { contents: projs.collect() } + } + + pub fn projections_and_spans( + &self, + ) -> impl Iterator<Item = &(UserTypeProjection, Span)> + ExactSizeIterator { + self.contents.iter() + } + + pub fn projections(&self) -> impl Iterator<Item = &UserTypeProjection> + ExactSizeIterator { + self.contents.iter().map(|&(ref user_type, _span)| user_type) + } + + pub fn push_projection(mut self, user_ty: &UserTypeProjection, span: Span) -> Self { + self.contents.push((user_ty.clone(), span)); + self + } + + fn map_projections( + mut self, + mut f: impl FnMut(UserTypeProjection) -> UserTypeProjection, + ) -> Self { + self.contents = self.contents.drain(..).map(|(proj, span)| (f(proj), span)).collect(); + self + } + + pub fn index(self) -> Self { + self.map_projections(|pat_ty_proj| pat_ty_proj.index()) + } + + pub fn subslice(self, from: u64, to: u64) -> Self { + self.map_projections(|pat_ty_proj| pat_ty_proj.subslice(from, to)) + } + + pub fn deref(self) -> Self { + self.map_projections(|pat_ty_proj| pat_ty_proj.deref()) + } + + pub fn leaf(self, field: Field) -> Self { + self.map_projections(|pat_ty_proj| pat_ty_proj.leaf(field)) + } + + pub fn variant(self, adt_def: &'tcx AdtDef, variant_index: VariantIdx, field: Field) -> Self { + self.map_projections(|pat_ty_proj| pat_ty_proj.variant(adt_def, variant_index, field)) + } +} + +/// Encodes the effect of a user-supplied type annotation on the +/// subcomponents of a pattern. The effect is determined by applying the +/// given list of proejctions to some underlying base type. Often, +/// the projection element list `projs` is empty, in which case this +/// directly encodes a type in `base`. But in the case of complex patterns with +/// subpatterns and bindings, we want to apply only a *part* of the type to a variable, +/// in which case the `projs` vector is used. +/// +/// Examples: +/// +/// * `let x: T = ...` -- here, the `projs` vector is empty. +/// +/// * `let (x, _): T = ...` -- here, the `projs` vector would contain +/// `field[0]` (aka `.0`), indicating that the type of `s` is +/// determined by finding the type of the `.0` field from `T`. +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, PartialEq)] +pub struct UserTypeProjection { + pub base: UserTypeAnnotationIndex, + pub projs: Vec<ProjectionKind>, +} + +impl Copy for ProjectionKind {} + +impl UserTypeProjection { + pub(crate) fn index(mut self) -> Self { + self.projs.push(ProjectionElem::Index(())); + self + } + + pub(crate) fn subslice(mut self, from: u64, to: u64) -> Self { + self.projs.push(ProjectionElem::Subslice { from, to, from_end: true }); + self + } + + pub(crate) fn deref(mut self) -> Self { + self.projs.push(ProjectionElem::Deref); + self + } + + pub(crate) fn leaf(mut self, field: Field) -> Self { + self.projs.push(ProjectionElem::Field(field, ())); + self + } + + pub(crate) fn variant( + mut self, + adt_def: &AdtDef, + variant_index: VariantIdx, + field: Field, + ) -> Self { + self.projs.push(ProjectionElem::Downcast( + Some(adt_def.variants[variant_index].ident.name), + variant_index, + )); + self.projs.push(ProjectionElem::Field(field, ())); + self + } +} + +CloneTypeFoldableAndLiftImpls! { ProjectionKind, } + +impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + use crate::mir::ProjectionElem::*; + + let base = self.base.fold_with(folder); + let projs: Vec<_> = self + .projs + .iter() + .map(|&elem| match elem { + Deref => Deref, + Field(f, ()) => Field(f, ()), + Index(()) => Index(()), + Downcast(symbol, variantidx) => Downcast(symbol, variantidx), + ConstantIndex { offset, min_length, from_end } => { + ConstantIndex { offset, min_length, from_end } + } + Subslice { from, to, from_end } => Subslice { from, to, from_end }, + }) + .collect(); + + UserTypeProjection { base, projs } + } + + fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool { + self.base.visit_with(visitor) + // Note: there's nothing in `self.proj` to visit. + } +} + +rustc_index::newtype_index! { + pub struct Promoted { + derive [HashStable] + DEBUG_FORMAT = "promoted[{}]" + } +} + +impl<'tcx> Debug for Constant<'tcx> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + write!(fmt, "{}", self) + } +} + +impl<'tcx> Display for Constant<'tcx> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + match self.literal.ty.kind { + ty::FnDef(..) => {} + _ => write!(fmt, "const ")?, + } + pretty_print_const(self.literal, fmt, true) + } +} + +fn pretty_print_const( + c: &ty::Const<'tcx>, + fmt: &mut Formatter<'_>, + print_types: bool, +) -> fmt::Result { + use crate::ty::print::PrettyPrinter; + ty::tls::with(|tcx| { + let literal = tcx.lift(&c).unwrap(); + let mut cx = FmtPrinter::new(tcx, fmt, Namespace::ValueNS); + cx.print_alloc_ids = true; + cx.pretty_print_const(literal, print_types)?; + Ok(()) + }) +} + +impl<'tcx> graph::DirectedGraph for Body<'tcx> { + type Node = BasicBlock; +} + +impl<'tcx> graph::WithNumNodes for Body<'tcx> { + #[inline] + fn num_nodes(&self) -> usize { + self.basic_blocks.len() + } +} + +impl<'tcx> graph::WithStartNode for Body<'tcx> { + #[inline] + fn start_node(&self) -> Self::Node { + START_BLOCK + } +} + +impl<'tcx> graph::WithSuccessors for Body<'tcx> { + #[inline] + fn successors(&self, node: Self::Node) -> <Self as GraphSuccessors<'_>>::Iter { + self.basic_blocks[node].terminator().successors().cloned() + } +} + +impl<'a, 'b> graph::GraphSuccessors<'b> for Body<'a> { + type Item = BasicBlock; + type Iter = iter::Cloned<Successors<'b>>; +} + +impl graph::GraphPredecessors<'graph> for Body<'tcx> { + type Item = BasicBlock; + type Iter = smallvec::IntoIter<[BasicBlock; 4]>; +} + +impl graph::WithPredecessors for Body<'tcx> { + #[inline] + fn predecessors(&self, node: Self::Node) -> <Self as graph::GraphPredecessors<'_>>::Iter { + self.predecessors()[node].clone().into_iter() + } +} + +/// `Location` represents the position of the start of the statement; or, if +/// `statement_index` equals the number of statements, then the start of the +/// terminator. +#[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd, HashStable)] +pub struct Location { + /// The block that the location is within. + pub block: BasicBlock, + + pub statement_index: usize, +} + +impl fmt::Debug for Location { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(fmt, "{:?}[{}]", self.block, self.statement_index) + } +} + +impl Location { + pub const START: Location = Location { block: START_BLOCK, statement_index: 0 }; + + /// Returns the location immediately after this one within the enclosing block. + /// + /// Note that if this location represents a terminator, then the + /// resulting location would be out of bounds and invalid. + pub fn successor_within_block(&self) -> Location { + Location { block: self.block, statement_index: self.statement_index + 1 } + } + + /// Returns `true` if `other` is earlier in the control flow graph than `self`. + pub fn is_predecessor_of<'tcx>(&self, other: Location, body: &Body<'tcx>) -> bool { + // If we are in the same block as the other location and are an earlier statement + // then we are a predecessor of `other`. + if self.block == other.block && self.statement_index < other.statement_index { + return true; + } + + let predecessors = body.predecessors(); + + // If we're in another block, then we want to check that block is a predecessor of `other`. + let mut queue: Vec<BasicBlock> = predecessors[other.block].to_vec(); + let mut visited = FxHashSet::default(); + + while let Some(block) = queue.pop() { + // If we haven't visited this block before, then make sure we visit it's predecessors. + if visited.insert(block) { + queue.extend(predecessors[block].iter().cloned()); + } else { + continue; + } + + // If we found the block that `self` is in, then we are a predecessor of `other` (since + // we found that block by looking at the predecessors of `other`). + if self.block == block { + return true; + } + } + + false + } + + pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool { + if self.block == other.block { + self.statement_index <= other.statement_index + } else { + dominators.is_dominated_by(other.block, self.block) + } + } +} diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs new file mode 100644 index 00000000000..0d5f6619df5 --- /dev/null +++ b/compiler/rustc_middle/src/mir/mono.rs @@ -0,0 +1,506 @@ +use crate::dep_graph::{DepConstructor, DepNode, WorkProduct, WorkProductId}; +use crate::ich::{NodeIdHashingMode, StableHashingContext}; +use crate::ty::print::obsolete::DefPathBasedNames; +use crate::ty::{subst::InternalSubsts, Instance, InstanceDef, SymbolName, TyCtxt}; +use rustc_attr::InlineAttr; +use rustc_data_structures::base_n; +use rustc_data_structures::fingerprint::Fingerprint; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE}; +use rustc_hir::HirId; +use rustc_session::config::OptLevel; +use rustc_span::source_map::Span; +use rustc_span::symbol::Symbol; +use std::fmt; +use std::hash::Hash; + +/// Describes how a monomorphization will be instantiated in object files. +#[derive(PartialEq)] +pub enum InstantiationMode { + /// There will be exactly one instance of the given MonoItem. It will have + /// external linkage so that it can be linked to from other codegen units. + GloballyShared { + /// In some compilation scenarios we may decide to take functions that + /// are typically `LocalCopy` and instead move them to `GloballyShared` + /// to avoid codegenning them a bunch of times. In this situation, + /// however, our local copy may conflict with other crates also + /// inlining the same function. + /// + /// This flag indicates that this situation is occurring, and informs + /// symbol name calculation that some extra mangling is needed to + /// avoid conflicts. Note that this may eventually go away entirely if + /// ThinLTO enables us to *always* have a globally shared instance of a + /// function within one crate's compilation. + may_conflict: bool, + }, + + /// Each codegen unit containing a reference to the given MonoItem will + /// have its own private copy of the function (with internal linkage). + LocalCopy, +} + +#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)] +pub enum MonoItem<'tcx> { + Fn(Instance<'tcx>), + Static(DefId), + GlobalAsm(HirId), +} + +impl<'tcx> MonoItem<'tcx> { + pub fn size_estimate(&self, tcx: TyCtxt<'tcx>) -> usize { + match *self { + MonoItem::Fn(instance) => { + // Estimate the size of a function based on how many statements + // it contains. + tcx.instance_def_size_estimate(instance.def) + } + // Conservatively estimate the size of a static declaration + // or assembly to be 1. + MonoItem::Static(_) | MonoItem::GlobalAsm(_) => 1, + } + } + + pub fn is_generic_fn(&self) -> bool { + match *self { + MonoItem::Fn(ref instance) => instance.substs.non_erasable_generics().next().is_some(), + MonoItem::Static(..) | MonoItem::GlobalAsm(..) => false, + } + } + + pub fn symbol_name(&self, tcx: TyCtxt<'tcx>) -> SymbolName<'tcx> { + match *self { + MonoItem::Fn(instance) => tcx.symbol_name(instance), + MonoItem::Static(def_id) => tcx.symbol_name(Instance::mono(tcx, def_id)), + MonoItem::GlobalAsm(hir_id) => { + let def_id = tcx.hir().local_def_id(hir_id); + SymbolName::new(tcx, &format!("global_asm_{:?}", def_id)) + } + } + } + + pub fn instantiation_mode(&self, tcx: TyCtxt<'tcx>) -> InstantiationMode { + let generate_cgu_internal_copies = tcx + .sess + .opts + .debugging_opts + .inline_in_all_cgus + .unwrap_or_else(|| tcx.sess.opts.optimize != OptLevel::No) + && tcx.sess.opts.cg.link_dead_code != Some(true); + + match *self { + MonoItem::Fn(ref instance) => { + let entry_def_id = tcx.entry_fn(LOCAL_CRATE).map(|(id, _)| id); + // If this function isn't inlined or otherwise has an extern + // indicator, then we'll be creating a globally shared version. + if tcx.codegen_fn_attrs(instance.def_id()).contains_extern_indicator() + || !instance.def.generates_cgu_internal_copy(tcx) + || Some(instance.def_id()) == entry_def_id.map(LocalDefId::to_def_id) + { + return InstantiationMode::GloballyShared { may_conflict: false }; + } + + // At this point we don't have explicit linkage and we're an + // inlined function. If we're inlining into all CGUs then we'll + // be creating a local copy per CGU. + if generate_cgu_internal_copies { + return InstantiationMode::LocalCopy; + } + + // Finally, if this is `#[inline(always)]` we're sure to respect + // that with an inline copy per CGU, but otherwise we'll be + // creating one copy of this `#[inline]` function which may + // conflict with upstream crates as it could be an exported + // symbol. + match tcx.codegen_fn_attrs(instance.def_id()).inline { + InlineAttr::Always => InstantiationMode::LocalCopy, + _ => InstantiationMode::GloballyShared { may_conflict: true }, + } + } + MonoItem::Static(..) | MonoItem::GlobalAsm(..) => { + InstantiationMode::GloballyShared { may_conflict: false } + } + } + } + + pub fn explicit_linkage(&self, tcx: TyCtxt<'tcx>) -> Option<Linkage> { + let def_id = match *self { + MonoItem::Fn(ref instance) => instance.def_id(), + MonoItem::Static(def_id) => def_id, + MonoItem::GlobalAsm(..) => return None, + }; + + let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id); + codegen_fn_attrs.linkage + } + + /// Returns `true` if this instance is instantiable - whether it has no unsatisfied + /// predicates. + /// + /// In order to codegen an item, all of its predicates must hold, because + /// otherwise the item does not make sense. Type-checking ensures that + /// the predicates of every item that is *used by* a valid item *do* + /// hold, so we can rely on that. + /// + /// However, we codegen collector roots (reachable items) and functions + /// in vtables when they are seen, even if they are not used, and so they + /// might not be instantiable. For example, a programmer can define this + /// public function: + /// + /// pub fn foo<'a>(s: &'a mut ()) where &'a mut (): Clone { + /// <&mut () as Clone>::clone(&s); + /// } + /// + /// That function can't be codegened, because the method `<&mut () as Clone>::clone` + /// does not exist. Luckily for us, that function can't ever be used, + /// because that would require for `&'a mut (): Clone` to hold, so we + /// can just not emit any code, or even a linker reference for it. + /// + /// Similarly, if a vtable method has such a signature, and therefore can't + /// be used, we can just not emit it and have a placeholder (a null pointer, + /// which will never be accessed) in its place. + pub fn is_instantiable(&self, tcx: TyCtxt<'tcx>) -> bool { + debug!("is_instantiable({:?})", self); + let (def_id, substs) = match *self { + MonoItem::Fn(ref instance) => (instance.def_id(), instance.substs), + MonoItem::Static(def_id) => (def_id, InternalSubsts::empty()), + // global asm never has predicates + MonoItem::GlobalAsm(..) => return true, + }; + + !tcx.subst_and_check_impossible_predicates((def_id, &substs)) + } + + pub fn to_string(&self, tcx: TyCtxt<'tcx>, debug: bool) -> String { + return match *self { + MonoItem::Fn(instance) => to_string_internal(tcx, "fn ", instance, debug), + MonoItem::Static(def_id) => { + let instance = Instance::new(def_id, tcx.intern_substs(&[])); + to_string_internal(tcx, "static ", instance, debug) + } + MonoItem::GlobalAsm(..) => "global_asm".to_string(), + }; + + fn to_string_internal<'tcx>( + tcx: TyCtxt<'tcx>, + prefix: &str, + instance: Instance<'tcx>, + debug: bool, + ) -> String { + let mut result = String::with_capacity(32); + result.push_str(prefix); + let printer = DefPathBasedNames::new(tcx, false, false); + printer.push_instance_as_string(instance, &mut result, debug); + result + } + } + + pub fn local_span(&self, tcx: TyCtxt<'tcx>) -> Option<Span> { + match *self { + MonoItem::Fn(Instance { def, .. }) => { + def.def_id().as_local().map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id)) + } + MonoItem::Static(def_id) => { + def_id.as_local().map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id)) + } + MonoItem::GlobalAsm(hir_id) => Some(hir_id), + } + .map(|hir_id| tcx.hir().span(hir_id)) + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for MonoItem<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + ::std::mem::discriminant(self).hash_stable(hcx, hasher); + + match *self { + MonoItem::Fn(ref instance) => { + instance.hash_stable(hcx, hasher); + } + MonoItem::Static(def_id) => { + def_id.hash_stable(hcx, hasher); + } + MonoItem::GlobalAsm(node_id) => { + hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { + node_id.hash_stable(hcx, hasher); + }) + } + } + } +} + +pub struct CodegenUnit<'tcx> { + /// A name for this CGU. Incremental compilation requires that + /// name be unique amongst **all** crates. Therefore, it should + /// contain something unique to this crate (e.g., a module path) + /// as well as the crate name and disambiguator. + name: Symbol, + items: FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)>, + size_estimate: Option<usize>, +} + +/// Specifies the linkage type for a `MonoItem`. +/// +/// See https://llvm.org/docs/LangRef.html#linkage-types for more details about these variants. +#[derive(Copy, Clone, PartialEq, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum Linkage { + External, + AvailableExternally, + LinkOnceAny, + LinkOnceODR, + WeakAny, + WeakODR, + Appending, + Internal, + Private, + ExternalWeak, + Common, +} + +#[derive(Copy, Clone, PartialEq, Debug, HashStable)] +pub enum Visibility { + Default, + Hidden, + Protected, +} + +impl<'tcx> CodegenUnit<'tcx> { + pub fn new(name: Symbol) -> CodegenUnit<'tcx> { + CodegenUnit { name, items: Default::default(), size_estimate: None } + } + + pub fn name(&self) -> Symbol { + self.name + } + + pub fn set_name(&mut self, name: Symbol) { + self.name = name; + } + + pub fn items(&self) -> &FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)> { + &self.items + } + + pub fn items_mut(&mut self) -> &mut FxHashMap<MonoItem<'tcx>, (Linkage, Visibility)> { + &mut self.items + } + + pub fn mangle_name(human_readable_name: &str) -> String { + // We generate a 80 bit hash from the name. This should be enough to + // avoid collisions and is still reasonably short for filenames. + let mut hasher = StableHasher::new(); + human_readable_name.hash(&mut hasher); + let hash: u128 = hasher.finish(); + let hash = hash & ((1u128 << 80) - 1); + base_n::encode(hash, base_n::CASE_INSENSITIVE) + } + + pub fn estimate_size(&mut self, tcx: TyCtxt<'tcx>) { + // Estimate the size of a codegen unit as (approximately) the number of MIR + // statements it corresponds to. + self.size_estimate = Some(self.items.keys().map(|mi| mi.size_estimate(tcx)).sum()); + } + + pub fn size_estimate(&self) -> usize { + // Should only be called if `estimate_size` has previously been called. + self.size_estimate.expect("estimate_size must be called before getting a size_estimate") + } + + pub fn modify_size_estimate(&mut self, delta: usize) { + assert!(self.size_estimate.is_some()); + if let Some(size_estimate) = self.size_estimate { + self.size_estimate = Some(size_estimate + delta); + } + } + + pub fn contains_item(&self, item: &MonoItem<'tcx>) -> bool { + self.items().contains_key(item) + } + + pub fn work_product_id(&self) -> WorkProductId { + WorkProductId::from_cgu_name(&self.name().as_str()) + } + + pub fn work_product(&self, tcx: TyCtxt<'_>) -> WorkProduct { + let work_product_id = self.work_product_id(); + tcx.dep_graph + .previous_work_product(&work_product_id) + .unwrap_or_else(|| panic!("Could not find work-product for CGU `{}`", self.name())) + } + + pub fn items_in_deterministic_order( + &self, + tcx: TyCtxt<'tcx>, + ) -> Vec<(MonoItem<'tcx>, (Linkage, Visibility))> { + // The codegen tests rely on items being process in the same order as + // they appear in the file, so for local items, we sort by node_id first + #[derive(PartialEq, Eq, PartialOrd, Ord)] + pub struct ItemSortKey<'tcx>(Option<HirId>, SymbolName<'tcx>); + + fn item_sort_key<'tcx>(tcx: TyCtxt<'tcx>, item: MonoItem<'tcx>) -> ItemSortKey<'tcx> { + ItemSortKey( + match item { + MonoItem::Fn(ref instance) => { + match instance.def { + // We only want to take HirIds of user-defined + // instances into account. The others don't matter for + // the codegen tests and can even make item order + // unstable. + InstanceDef::Item(def) => def + .did + .as_local() + .map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id)), + InstanceDef::VtableShim(..) + | InstanceDef::ReifyShim(..) + | InstanceDef::Intrinsic(..) + | InstanceDef::FnPtrShim(..) + | InstanceDef::Virtual(..) + | InstanceDef::ClosureOnceShim { .. } + | InstanceDef::DropGlue(..) + | InstanceDef::CloneShim(..) => None, + } + } + MonoItem::Static(def_id) => { + def_id.as_local().map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id)) + } + MonoItem::GlobalAsm(hir_id) => Some(hir_id), + }, + item.symbol_name(tcx), + ) + } + + let mut items: Vec<_> = self.items().iter().map(|(&i, &l)| (i, l)).collect(); + items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i)); + items + } + + pub fn codegen_dep_node(&self, tcx: TyCtxt<'tcx>) -> DepNode { + DepConstructor::CompileCodegenUnit(tcx, self.name()) + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for CodegenUnit<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let CodegenUnit { + ref items, + name, + // The size estimate is not relevant to the hash + size_estimate: _, + } = *self; + + name.hash_stable(hcx, hasher); + + let mut items: Vec<(Fingerprint, _)> = items + .iter() + .map(|(mono_item, &attrs)| { + let mut hasher = StableHasher::new(); + mono_item.hash_stable(hcx, &mut hasher); + let mono_item_fingerprint = hasher.finish(); + (mono_item_fingerprint, attrs) + }) + .collect(); + + items.sort_unstable_by_key(|i| i.0); + items.hash_stable(hcx, hasher); + } +} + +pub struct CodegenUnitNameBuilder<'tcx> { + tcx: TyCtxt<'tcx>, + cache: FxHashMap<CrateNum, String>, +} + +impl CodegenUnitNameBuilder<'tcx> { + pub fn new(tcx: TyCtxt<'tcx>) -> Self { + CodegenUnitNameBuilder { tcx, cache: Default::default() } + } + + /// CGU names should fulfill the following requirements: + /// - They should be able to act as a file name on any kind of file system + /// - They should not collide with other CGU names, even for different versions + /// of the same crate. + /// + /// Consequently, we don't use special characters except for '.' and '-' and we + /// prefix each name with the crate-name and crate-disambiguator. + /// + /// This function will build CGU names of the form: + /// + /// ``` + /// <crate-name>.<crate-disambiguator>[-in-<local-crate-id>](-<component>)*[.<special-suffix>] + /// <local-crate-id> = <local-crate-name>.<local-crate-disambiguator> + /// ``` + /// + /// The '.' before `<special-suffix>` makes sure that names with a special + /// suffix can never collide with a name built out of regular Rust + /// identifiers (e.g., module paths). + pub fn build_cgu_name<I, C, S>( + &mut self, + cnum: CrateNum, + components: I, + special_suffix: Option<S>, + ) -> Symbol + where + I: IntoIterator<Item = C>, + C: fmt::Display, + S: fmt::Display, + { + let cgu_name = self.build_cgu_name_no_mangle(cnum, components, special_suffix); + + if self.tcx.sess.opts.debugging_opts.human_readable_cgu_names { + cgu_name + } else { + Symbol::intern(&CodegenUnit::mangle_name(&cgu_name.as_str())) + } + } + + /// Same as `CodegenUnit::build_cgu_name()` but will never mangle the + /// resulting name. + pub fn build_cgu_name_no_mangle<I, C, S>( + &mut self, + cnum: CrateNum, + components: I, + special_suffix: Option<S>, + ) -> Symbol + where + I: IntoIterator<Item = C>, + C: fmt::Display, + S: fmt::Display, + { + use std::fmt::Write; + + let mut cgu_name = String::with_capacity(64); + + // Start out with the crate name and disambiguator + let tcx = self.tcx; + let crate_prefix = self.cache.entry(cnum).or_insert_with(|| { + // Whenever the cnum is not LOCAL_CRATE we also mix in the + // local crate's ID. Otherwise there can be collisions between CGUs + // instantiating stuff for upstream crates. + let local_crate_id = if cnum != LOCAL_CRATE { + let local_crate_disambiguator = format!("{}", tcx.crate_disambiguator(LOCAL_CRATE)); + format!("-in-{}.{}", tcx.crate_name(LOCAL_CRATE), &local_crate_disambiguator[0..8]) + } else { + String::new() + }; + + let crate_disambiguator = tcx.crate_disambiguator(cnum).to_string(); + // Using a shortened disambiguator of about 40 bits + format!("{}.{}{}", tcx.crate_name(cnum), &crate_disambiguator[0..8], local_crate_id) + }); + + write!(cgu_name, "{}", crate_prefix).unwrap(); + + // Add the components + for component in components { + write!(cgu_name, "-{}", component).unwrap(); + } + + if let Some(special_suffix) = special_suffix { + // We add a dot in here so it cannot clash with anything in a regular + // Rust identifier + write!(cgu_name, ".{}", special_suffix).unwrap(); + } + + Symbol::intern(&cgu_name[..]) + } +} diff --git a/compiler/rustc_middle/src/mir/predecessors.rs b/compiler/rustc_middle/src/mir/predecessors.rs new file mode 100644 index 00000000000..b16a1d53fff --- /dev/null +++ b/compiler/rustc_middle/src/mir/predecessors.rs @@ -0,0 +1,80 @@ +//! Lazily compute the reverse control-flow graph for the MIR. + +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_data_structures::sync::OnceCell; +use rustc_index::vec::IndexVec; +use rustc_serialize as serialize; +use smallvec::SmallVec; + +use crate::mir::{BasicBlock, BasicBlockData}; + +// Typically 95%+ of basic blocks have 4 or fewer predecessors. +pub type Predecessors = IndexVec<BasicBlock, SmallVec<[BasicBlock; 4]>>; + +#[derive(Clone, Debug)] +pub(super) struct PredecessorCache { + cache: OnceCell<Predecessors>, +} + +impl PredecessorCache { + #[inline] + pub(super) fn new() -> Self { + PredecessorCache { cache: OnceCell::new() } + } + + /// Invalidates the predecessor cache. + #[inline] + pub(super) fn invalidate(&mut self) { + // Invalidating the predecessor cache requires mutating the MIR, which in turn requires a + // unique reference (`&mut`) to the `mir::Body`. Because of this, we can assume that all + // callers of `invalidate` have a unique reference to the MIR and thus to the predecessor + // cache. This means we never need to do synchronization when `invalidate` is called, we can + // simply reinitialize the `OnceCell`. + self.cache = OnceCell::new(); + } + + /// Returns the the predecessor graph for this MIR. + #[inline] + pub(super) fn compute( + &self, + basic_blocks: &IndexVec<BasicBlock, BasicBlockData<'_>>, + ) -> &Predecessors { + self.cache.get_or_init(|| { + let mut preds = IndexVec::from_elem(SmallVec::new(), basic_blocks); + for (bb, data) in basic_blocks.iter_enumerated() { + if let Some(term) = &data.terminator { + for &succ in term.successors() { + preds[succ].push(bb); + } + } + } + + preds + }) + } +} + +impl<S: serialize::Encoder> serialize::Encodable<S> for PredecessorCache { + #[inline] + fn encode(&self, s: &mut S) -> Result<(), S::Error> { + serialize::Encodable::encode(&(), s) + } +} + +impl<D: serialize::Decoder> serialize::Decodable<D> for PredecessorCache { + #[inline] + fn decode(d: &mut D) -> Result<Self, D::Error> { + serialize::Decodable::decode(d).map(|_v: ()| Self::new()) + } +} + +impl<CTX> HashStable<CTX> for PredecessorCache { + #[inline] + fn hash_stable(&self, _: &mut CTX, _: &mut StableHasher) { + // do nothing + } +} + +CloneTypeFoldableAndLiftImpls! { + PredecessorCache, +} diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs new file mode 100644 index 00000000000..0878e9313d8 --- /dev/null +++ b/compiler/rustc_middle/src/mir/query.rs @@ -0,0 +1,443 @@ +//! Values computed by queries that use MIR. + +use crate::mir::{Body, Promoted}; +use crate::ty::{self, Ty, TyCtxt}; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::sync::Lrc; +use rustc_hir as hir; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_index::bit_set::BitMatrix; +use rustc_index::vec::IndexVec; +use rustc_span::Span; +use rustc_target::abi::VariantIdx; +use smallvec::SmallVec; +use std::cell::Cell; +use std::fmt::{self, Debug}; + +use super::{Field, SourceInfo}; + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable)] +pub enum UnsafetyViolationKind { + /// Only permitted in regular `fn`s, prohibited in `const fn`s. + General, + /// Permitted both in `const fn`s and regular `fn`s. + GeneralAndConstFn, + /// Borrow of packed field. + /// Has to be handled as a lint for backwards compatibility. + BorrowPacked, + /// Unsafe operation in an `unsafe fn` but outside an `unsafe` block. + /// Has to be handled as a lint for backwards compatibility. + /// Should stay gated under `#![feature(unsafe_block_in_unsafe_fn)]`. + UnsafeFn, + /// Borrow of packed field in an `unsafe fn` but outside an `unsafe` block. + /// Has to be handled as a lint for backwards compatibility. + /// Should stay gated under `#![feature(unsafe_block_in_unsafe_fn)]`. + UnsafeFnBorrowPacked, +} + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable)] +pub enum UnsafetyViolationDetails { + CallToUnsafeFunction, + UseOfInlineAssembly, + InitializingTypeWith, + CastOfPointerToInt, + BorrowOfPackedField, + UseOfMutableStatic, + UseOfExternStatic, + DerefOfRawPointer, + AssignToNonCopyUnionField, + AccessToUnionField, + MutationOfLayoutConstrainedField, + BorrowOfLayoutConstrainedField, + CallToFunctionWith, +} + +impl UnsafetyViolationDetails { + pub fn description_and_note(&self) -> (&'static str, &'static str) { + use UnsafetyViolationDetails::*; + match self { + CallToUnsafeFunction => ( + "call to unsafe function", + "consult the function's documentation for information on how to avoid undefined \ + behavior", + ), + UseOfInlineAssembly => ( + "use of inline assembly", + "inline assembly is entirely unchecked and can cause undefined behavior", + ), + InitializingTypeWith => ( + "initializing type with `rustc_layout_scalar_valid_range` attr", + "initializing a layout restricted type's field with a value outside the valid \ + range is undefined behavior", + ), + CastOfPointerToInt => { + ("cast of pointer to int", "casting pointers to integers in constants") + } + BorrowOfPackedField => ( + "borrow of packed field", + "fields of packed structs might be misaligned: dereferencing a misaligned pointer \ + or even just creating a misaligned reference is undefined behavior", + ), + UseOfMutableStatic => ( + "use of mutable static", + "mutable statics can be mutated by multiple threads: aliasing violations or data \ + races will cause undefined behavior", + ), + UseOfExternStatic => ( + "use of extern static", + "extern statics are not controlled by the Rust type system: invalid data, \ + aliasing violations or data races will cause undefined behavior", + ), + DerefOfRawPointer => ( + "dereference of raw pointer", + "raw pointers may be NULL, dangling or unaligned; they can violate aliasing rules \ + and cause data races: all of these are undefined behavior", + ), + AssignToNonCopyUnionField => ( + "assignment to non-`Copy` union field", + "the previous content of the field will be dropped, which causes undefined \ + behavior if the field was not properly initialized", + ), + AccessToUnionField => ( + "access to union field", + "the field may not be properly initialized: using uninitialized data will cause \ + undefined behavior", + ), + MutationOfLayoutConstrainedField => ( + "mutation of layout constrained field", + "mutating layout constrained fields cannot statically be checked for valid values", + ), + BorrowOfLayoutConstrainedField => ( + "borrow of layout constrained field with interior mutability", + "references to fields of layout constrained fields lose the constraints. Coupled \ + with interior mutability, the field can be changed to invalid values", + ), + CallToFunctionWith => ( + "call to function with `#[target_feature]`", + "can only be called if the required target features are available", + ), + } + } +} + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable)] +pub struct UnsafetyViolation { + pub source_info: SourceInfo, + pub lint_root: hir::HirId, + pub kind: UnsafetyViolationKind, + pub details: UnsafetyViolationDetails, +} + +#[derive(Clone, TyEncodable, TyDecodable, HashStable)] +pub struct UnsafetyCheckResult { + /// Violations that are propagated *upwards* from this function. + pub violations: Lrc<[UnsafetyViolation]>, + /// `unsafe` blocks in this function, along with whether they are used. This is + /// used for the "unused_unsafe" lint. + pub unsafe_blocks: Lrc<[(hir::HirId, bool)]>, +} + +rustc_index::newtype_index! { + pub struct GeneratorSavedLocal { + derive [HashStable] + DEBUG_FORMAT = "_{}", + } +} + +/// The layout of generator state. +#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct GeneratorLayout<'tcx> { + /// The type of every local stored inside the generator. + pub field_tys: IndexVec<GeneratorSavedLocal, Ty<'tcx>>, + + /// Which of the above fields are in each variant. Note that one field may + /// be stored in multiple variants. + pub variant_fields: IndexVec<VariantIdx, IndexVec<Field, GeneratorSavedLocal>>, + + /// The source that led to each variant being created (usually, a yield or + /// await). + pub variant_source_info: IndexVec<VariantIdx, SourceInfo>, + + /// Which saved locals are storage-live at the same time. Locals that do not + /// have conflicts with each other are allowed to overlap in the computed + /// layout. + pub storage_conflicts: BitMatrix<GeneratorSavedLocal, GeneratorSavedLocal>, +} + +impl Debug for GeneratorLayout<'_> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + /// Prints an iterator of (key, value) tuples as a map. + struct MapPrinter<'a, K, V>(Cell<Option<Box<dyn Iterator<Item = (K, V)> + 'a>>>); + impl<'a, K, V> MapPrinter<'a, K, V> { + fn new(iter: impl Iterator<Item = (K, V)> + 'a) -> Self { + Self(Cell::new(Some(Box::new(iter)))) + } + } + impl<'a, K: Debug, V: Debug> Debug for MapPrinter<'a, K, V> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt.debug_map().entries(self.0.take().unwrap()).finish() + } + } + + /// Prints the generator variant name. + struct GenVariantPrinter(VariantIdx); + impl From<VariantIdx> for GenVariantPrinter { + fn from(idx: VariantIdx) -> Self { + GenVariantPrinter(idx) + } + } + impl Debug for GenVariantPrinter { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + let variant_name = ty::GeneratorSubsts::variant_name(self.0); + if fmt.alternate() { + write!(fmt, "{:9}({:?})", variant_name, self.0) + } else { + write!(fmt, "{}", variant_name) + } + } + } + + /// Forces its contents to print in regular mode instead of alternate mode. + struct OneLinePrinter<T>(T); + impl<T: Debug> Debug for OneLinePrinter<T> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(fmt, "{:?}", self.0) + } + } + + fmt.debug_struct("GeneratorLayout") + .field("field_tys", &MapPrinter::new(self.field_tys.iter_enumerated())) + .field( + "variant_fields", + &MapPrinter::new( + self.variant_fields + .iter_enumerated() + .map(|(k, v)| (GenVariantPrinter(k), OneLinePrinter(v))), + ), + ) + .field("storage_conflicts", &self.storage_conflicts) + .finish() + } +} + +#[derive(Debug, TyEncodable, TyDecodable, HashStable)] +pub struct BorrowCheckResult<'tcx> { + /// All the opaque types that are restricted to concrete types + /// by this function. Unlike the value in `TypeckResults`, this has + /// unerased regions. + pub concrete_opaque_types: FxHashMap<DefId, ty::ResolvedOpaqueTy<'tcx>>, + pub closure_requirements: Option<ClosureRegionRequirements<'tcx>>, + pub used_mut_upvars: SmallVec<[Field; 8]>, +} + +/// The result of the `mir_const_qualif` query. +/// +/// Each field corresponds to an implementer of the `Qualif` trait in +/// `librustc_mir/transform/check_consts/qualifs.rs`. See that file for more information on each +/// `Qualif`. +#[derive(Clone, Copy, Debug, Default, TyEncodable, TyDecodable, HashStable)] +pub struct ConstQualifs { + pub has_mut_interior: bool, + pub needs_drop: bool, + pub custom_eq: bool, +} + +/// After we borrow check a closure, we are left with various +/// requirements that we have inferred between the free regions that +/// appear in the closure's signature or on its field types. These +/// requirements are then verified and proved by the closure's +/// creating function. This struct encodes those requirements. +/// +/// The requirements are listed as being between various `RegionVid`. The 0th +/// region refers to `'static`; subsequent region vids refer to the free +/// regions that appear in the closure (or generator's) type, in order of +/// appearance. (This numbering is actually defined by the `UniversalRegions` +/// struct in the NLL region checker. See for example +/// `UniversalRegions::closure_mapping`.) Note the free regions in the +/// closure's signature and captures are erased. +/// +/// Example: If type check produces a closure with the closure substs: +/// +/// ```text +/// ClosureSubsts = [ +/// 'a, // From the parent. +/// 'b, +/// i8, // the "closure kind" +/// for<'x> fn(&'<erased> &'x u32) -> &'x u32, // the "closure signature" +/// &'<erased> String, // some upvar +/// ] +/// ``` +/// +/// We would "renumber" each free region to a unique vid, as follows: +/// +/// ```text +/// ClosureSubsts = [ +/// '1, // From the parent. +/// '2, +/// i8, // the "closure kind" +/// for<'x> fn(&'3 &'x u32) -> &'x u32, // the "closure signature" +/// &'4 String, // some upvar +/// ] +/// ``` +/// +/// Now the code might impose a requirement like `'1: '2`. When an +/// instance of the closure is created, the corresponding free regions +/// can be extracted from its type and constrained to have the given +/// outlives relationship. +/// +/// In some cases, we have to record outlives requirements between types and +/// regions as well. In that case, if those types include any regions, those +/// regions are recorded using their external names (`ReStatic`, +/// `ReEarlyBound`, `ReFree`). We use these because in a query response we +/// cannot use `ReVar` (which is what we use internally within the rest of the +/// NLL code). +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct ClosureRegionRequirements<'tcx> { + /// The number of external regions defined on the closure. In our + /// example above, it would be 3 -- one for `'static`, then `'1` + /// and `'2`. This is just used for a sanity check later on, to + /// make sure that the number of regions we see at the callsite + /// matches. + pub num_external_vids: usize, + + /// Requirements between the various free regions defined in + /// indices. + pub outlives_requirements: Vec<ClosureOutlivesRequirement<'tcx>>, +} + +/// Indicates an outlives-constraint between a type or between two +/// free regions declared on the closure. +#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct ClosureOutlivesRequirement<'tcx> { + // This region or type ... + pub subject: ClosureOutlivesSubject<'tcx>, + + // ... must outlive this one. + pub outlived_free_region: ty::RegionVid, + + // If not, report an error here ... + pub blame_span: Span, + + // ... due to this reason. + pub category: ConstraintCategory, +} + +/// Outlives-constraints can be categorized to determine whether and why they +/// are interesting (for error reporting). Order of variants indicates sort +/// order of the category, thereby influencing diagnostic output. +/// +/// See also `rustc_mir::borrow_check::constraints`. +#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)] +#[derive(TyEncodable, TyDecodable, HashStable)] +pub enum ConstraintCategory { + Return(ReturnConstraint), + Yield, + UseAsConst, + UseAsStatic, + TypeAnnotation, + Cast, + + /// A constraint that came from checking the body of a closure. + /// + /// We try to get the category that the closure used when reporting this. + ClosureBounds, + CallArgument, + CopyBound, + SizedBound, + Assignment, + OpaqueType, + ClosureUpvar(hir::HirId), + + /// A "boring" constraint (caused by the given location) is one that + /// the user probably doesn't want to see described in diagnostics, + /// because it is kind of an artifact of the type system setup. + /// Example: `x = Foo { field: y }` technically creates + /// intermediate regions representing the "type of `Foo { field: y + /// }`", and data flows from `y` into those variables, but they + /// are not very interesting. The assignment into `x` on the other + /// hand might be. + Boring, + // Boring and applicable everywhere. + BoringNoLocation, + + /// A constraint that doesn't correspond to anything the user sees. + Internal, +} + +#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)] +#[derive(TyEncodable, TyDecodable, HashStable)] +pub enum ReturnConstraint { + Normal, + ClosureUpvar(hir::HirId), +} + +/// The subject of a `ClosureOutlivesRequirement` -- that is, the thing +/// that must outlive some region. +#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum ClosureOutlivesSubject<'tcx> { + /// Subject is a type, typically a type parameter, but could also + /// be a projection. Indicates a requirement like `T: 'a` being + /// passed to the caller, where the type here is `T`. + /// + /// The type here is guaranteed not to contain any free regions at + /// present. + Ty(Ty<'tcx>), + + /// Subject is a free region from the closure. Indicates a requirement + /// like `'a: 'b` being passed to the caller; the region here is `'a`. + Region(ty::RegionVid), +} + +/// The constituent parts of an ADT or array. +#[derive(Copy, Clone, Debug, HashStable)] +pub struct DestructuredConst<'tcx> { + pub variant: Option<VariantIdx>, + pub fields: &'tcx [&'tcx ty::Const<'tcx>], +} + +/// Coverage information summarized from a MIR if instrumented for source code coverage (see +/// compiler option `-Zinstrument-coverage`). This information is generated by the +/// `InstrumentCoverage` MIR pass and can be retrieved via the `coverageinfo` query. +#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable)] +pub struct CoverageInfo { + /// The total number of coverage region counters added to the MIR `Body`. + pub num_counters: u32, + + /// The total number of coverage region counter expressions added to the MIR `Body`. + pub num_expressions: u32, +} + +impl<'tcx> TyCtxt<'tcx> { + pub fn mir_borrowck_opt_const_arg( + self, + def: ty::WithOptConstParam<LocalDefId>, + ) -> &'tcx BorrowCheckResult<'tcx> { + if let Some(param_did) = def.const_param_did { + self.mir_borrowck_const_arg((def.did, param_did)) + } else { + self.mir_borrowck(def.did) + } + } + + pub fn mir_const_qualif_opt_const_arg( + self, + def: ty::WithOptConstParam<LocalDefId>, + ) -> ConstQualifs { + if let Some(param_did) = def.const_param_did { + self.mir_const_qualif_const_arg((def.did, param_did)) + } else { + self.mir_const_qualif(def.did) + } + } + + pub fn promoted_mir_of_opt_const_arg( + self, + def: ty::WithOptConstParam<DefId>, + ) -> &'tcx IndexVec<Promoted, Body<'tcx>> { + if let Some((did, param_did)) = def.as_const_arg() { + self.promoted_mir_of_const_arg((did, param_did)) + } else { + self.promoted_mir(def.did) + } + } +} diff --git a/compiler/rustc_middle/src/mir/tcx.rs b/compiler/rustc_middle/src/mir/tcx.rs new file mode 100644 index 00000000000..efcd41e5c18 --- /dev/null +++ b/compiler/rustc_middle/src/mir/tcx.rs @@ -0,0 +1,287 @@ +/*! + * Methods for the various MIR types. These are intended for use after + * building is complete. + */ + +use crate::mir::*; +use crate::ty::subst::Subst; +use crate::ty::{self, Ty, TyCtxt}; +use rustc_hir as hir; +use rustc_target::abi::VariantIdx; + +#[derive(Copy, Clone, Debug, TypeFoldable)] +pub struct PlaceTy<'tcx> { + pub ty: Ty<'tcx>, + /// Downcast to a particular variant of an enum, if included. + pub variant_index: Option<VariantIdx>, +} + +// At least on 64 bit systems, `PlaceTy` should not be larger than two or three pointers. +#[cfg(target_arch = "x86_64")] +static_assert_size!(PlaceTy<'_>, 16); + +impl<'tcx> PlaceTy<'tcx> { + pub fn from_ty(ty: Ty<'tcx>) -> PlaceTy<'tcx> { + PlaceTy { ty, variant_index: None } + } + + /// `place_ty.field_ty(tcx, f)` computes the type at a given field + /// of a record or enum-variant. (Most clients of `PlaceTy` can + /// instead just extract the relevant type directly from their + /// `PlaceElem`, but some instances of `ProjectionElem<V, T>` do + /// not carry a `Ty` for `T`.) + /// + /// Note that the resulting type has not been normalized. + pub fn field_ty(self, tcx: TyCtxt<'tcx>, f: &Field) -> Ty<'tcx> { + let answer = match self.ty.kind { + ty::Adt(adt_def, substs) => { + let variant_def = match self.variant_index { + None => adt_def.non_enum_variant(), + Some(variant_index) => { + assert!(adt_def.is_enum()); + &adt_def.variants[variant_index] + } + }; + let field_def = &variant_def.fields[f.index()]; + field_def.ty(tcx, substs) + } + ty::Tuple(ref tys) => tys[f.index()].expect_ty(), + _ => bug!("extracting field of non-tuple non-adt: {:?}", self), + }; + debug!("field_ty self: {:?} f: {:?} yields: {:?}", self, f, answer); + answer + } + + /// Convenience wrapper around `projection_ty_core` for + /// `PlaceElem`, where we can just use the `Ty` that is already + /// stored inline on field projection elems. + pub fn projection_ty(self, tcx: TyCtxt<'tcx>, elem: PlaceElem<'tcx>) -> PlaceTy<'tcx> { + self.projection_ty_core(tcx, ty::ParamEnv::empty(), &elem, |_, _, ty| ty) + } + + /// `place_ty.projection_ty_core(tcx, elem, |...| { ... })` + /// projects `place_ty` onto `elem`, returning the appropriate + /// `Ty` or downcast variant corresponding to that projection. + /// The `handle_field` callback must map a `Field` to its `Ty`, + /// (which should be trivial when `T` = `Ty`). + pub fn projection_ty_core<V, T>( + self, + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + elem: &ProjectionElem<V, T>, + mut handle_field: impl FnMut(&Self, &Field, &T) -> Ty<'tcx>, + ) -> PlaceTy<'tcx> + where + V: ::std::fmt::Debug, + T: ::std::fmt::Debug, + { + let answer = match *elem { + ProjectionElem::Deref => { + let ty = self + .ty + .builtin_deref(true) + .unwrap_or_else(|| { + bug!("deref projection of non-dereferenceable ty {:?}", self) + }) + .ty; + PlaceTy::from_ty(ty) + } + ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } => { + PlaceTy::from_ty(self.ty.builtin_index().unwrap()) + } + ProjectionElem::Subslice { from, to, from_end } => { + PlaceTy::from_ty(match self.ty.kind { + ty::Slice(..) => self.ty, + ty::Array(inner, _) if !from_end => tcx.mk_array(inner, (to - from) as u64), + ty::Array(inner, size) if from_end => { + let size = size.eval_usize(tcx, param_env); + let len = size - (from as u64) - (to as u64); + tcx.mk_array(inner, len) + } + _ => bug!("cannot subslice non-array type: `{:?}`", self), + }) + } + ProjectionElem::Downcast(_name, index) => { + PlaceTy { ty: self.ty, variant_index: Some(index) } + } + ProjectionElem::Field(ref f, ref fty) => PlaceTy::from_ty(handle_field(&self, f, fty)), + }; + debug!("projection_ty self: {:?} elem: {:?} yields: {:?}", self, elem, answer); + answer + } +} + +impl<'tcx> Place<'tcx> { + pub fn ty_from<D>( + local: Local, + projection: &[PlaceElem<'tcx>], + local_decls: &D, + tcx: TyCtxt<'tcx>, + ) -> PlaceTy<'tcx> + where + D: HasLocalDecls<'tcx>, + { + projection + .iter() + .fold(PlaceTy::from_ty(local_decls.local_decls()[local].ty), |place_ty, &elem| { + place_ty.projection_ty(tcx, elem) + }) + } + + pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> PlaceTy<'tcx> + where + D: HasLocalDecls<'tcx>, + { + Place::ty_from(self.local, &self.projection, local_decls, tcx) + } +} + +pub enum RvalueInitializationState { + Shallow, + Deep, +} + +impl<'tcx> Rvalue<'tcx> { + pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx> + where + D: HasLocalDecls<'tcx>, + { + match *self { + Rvalue::Use(ref operand) => operand.ty(local_decls, tcx), + Rvalue::Repeat(ref operand, count) => { + tcx.mk_ty(ty::Array(operand.ty(local_decls, tcx), count)) + } + Rvalue::ThreadLocalRef(did) => { + if tcx.is_mutable_static(did) { + tcx.mk_mut_ptr(tcx.type_of(did)) + } else { + tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.type_of(did)) + } + } + Rvalue::Ref(reg, bk, ref place) => { + let place_ty = place.ty(local_decls, tcx).ty; + tcx.mk_ref(reg, ty::TypeAndMut { ty: place_ty, mutbl: bk.to_mutbl_lossy() }) + } + Rvalue::AddressOf(mutability, ref place) => { + let place_ty = place.ty(local_decls, tcx).ty; + tcx.mk_ptr(ty::TypeAndMut { ty: place_ty, mutbl: mutability }) + } + Rvalue::Len(..) => tcx.types.usize, + Rvalue::Cast(.., ty) => ty, + Rvalue::BinaryOp(op, ref lhs, ref rhs) => { + let lhs_ty = lhs.ty(local_decls, tcx); + let rhs_ty = rhs.ty(local_decls, tcx); + op.ty(tcx, lhs_ty, rhs_ty) + } + Rvalue::CheckedBinaryOp(op, ref lhs, ref rhs) => { + let lhs_ty = lhs.ty(local_decls, tcx); + let rhs_ty = rhs.ty(local_decls, tcx); + let ty = op.ty(tcx, lhs_ty, rhs_ty); + tcx.intern_tup(&[ty, tcx.types.bool]) + } + Rvalue::UnaryOp(UnOp::Not | UnOp::Neg, ref operand) => operand.ty(local_decls, tcx), + Rvalue::Discriminant(ref place) => place.ty(local_decls, tcx).ty.discriminant_ty(tcx), + Rvalue::NullaryOp(NullOp::Box, t) => tcx.mk_box(t), + Rvalue::NullaryOp(NullOp::SizeOf, _) => tcx.types.usize, + Rvalue::Aggregate(ref ak, ref ops) => match **ak { + AggregateKind::Array(ty) => tcx.mk_array(ty, ops.len() as u64), + AggregateKind::Tuple => tcx.mk_tup(ops.iter().map(|op| op.ty(local_decls, tcx))), + AggregateKind::Adt(def, _, substs, _, _) => tcx.type_of(def.did).subst(tcx, substs), + AggregateKind::Closure(did, substs) => tcx.mk_closure(did, substs), + AggregateKind::Generator(did, substs, movability) => { + tcx.mk_generator(did, substs, movability) + } + }, + } + } + + #[inline] + /// Returns `true` if this rvalue is deeply initialized (most rvalues) or + /// whether its only shallowly initialized (`Rvalue::Box`). + pub fn initialization_state(&self) -> RvalueInitializationState { + match *self { + Rvalue::NullaryOp(NullOp::Box, _) => RvalueInitializationState::Shallow, + _ => RvalueInitializationState::Deep, + } + } +} + +impl<'tcx> Operand<'tcx> { + pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx> + where + D: HasLocalDecls<'tcx>, + { + match self { + &Operand::Copy(ref l) | &Operand::Move(ref l) => l.ty(local_decls, tcx).ty, + &Operand::Constant(ref c) => c.literal.ty, + } + } +} + +impl<'tcx> BinOp { + pub fn ty(&self, tcx: TyCtxt<'tcx>, lhs_ty: Ty<'tcx>, rhs_ty: Ty<'tcx>) -> Ty<'tcx> { + // FIXME: handle SIMD correctly + match self { + &BinOp::Add + | &BinOp::Sub + | &BinOp::Mul + | &BinOp::Div + | &BinOp::Rem + | &BinOp::BitXor + | &BinOp::BitAnd + | &BinOp::BitOr => { + // these should be integers or floats of the same size. + assert_eq!(lhs_ty, rhs_ty); + lhs_ty + } + &BinOp::Shl | &BinOp::Shr | &BinOp::Offset => { + lhs_ty // lhs_ty can be != rhs_ty + } + &BinOp::Eq | &BinOp::Lt | &BinOp::Le | &BinOp::Ne | &BinOp::Ge | &BinOp::Gt => { + tcx.types.bool + } + } + } +} + +impl BorrowKind { + pub fn to_mutbl_lossy(self) -> hir::Mutability { + match self { + BorrowKind::Mut { .. } => hir::Mutability::Mut, + BorrowKind::Shared => hir::Mutability::Not, + + // We have no type corresponding to a unique imm borrow, so + // use `&mut`. It gives all the capabilities of an `&uniq` + // and hence is a safe "over approximation". + BorrowKind::Unique => hir::Mutability::Mut, + + // We have no type corresponding to a shallow borrow, so use + // `&` as an approximation. + BorrowKind::Shallow => hir::Mutability::Not, + } + } +} + +impl BinOp { + pub fn to_hir_binop(self) -> hir::BinOpKind { + match self { + BinOp::Add => hir::BinOpKind::Add, + BinOp::Sub => hir::BinOpKind::Sub, + BinOp::Mul => hir::BinOpKind::Mul, + BinOp::Div => hir::BinOpKind::Div, + BinOp::Rem => hir::BinOpKind::Rem, + BinOp::BitXor => hir::BinOpKind::BitXor, + BinOp::BitAnd => hir::BinOpKind::BitAnd, + BinOp::BitOr => hir::BinOpKind::BitOr, + BinOp::Shl => hir::BinOpKind::Shl, + BinOp::Shr => hir::BinOpKind::Shr, + BinOp::Eq => hir::BinOpKind::Eq, + BinOp::Ne => hir::BinOpKind::Ne, + BinOp::Lt => hir::BinOpKind::Lt, + BinOp::Gt => hir::BinOpKind::Gt, + BinOp::Le => hir::BinOpKind::Le, + BinOp::Ge => hir::BinOpKind::Ge, + BinOp::Offset => unreachable!(), + } + } +} diff --git a/compiler/rustc_middle/src/mir/terminator/mod.rs b/compiler/rustc_middle/src/mir/terminator/mod.rs new file mode 100644 index 00000000000..fcfd648c2b7 --- /dev/null +++ b/compiler/rustc_middle/src/mir/terminator/mod.rs @@ -0,0 +1,507 @@ +use crate::mir::interpret::Scalar; +use crate::ty::{self, Ty, TyCtxt}; +use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece}; + +use super::{ + AssertMessage, BasicBlock, InlineAsmOperand, Operand, Place, SourceInfo, Successors, + SuccessorsMut, +}; +pub use rustc_ast::Mutability; +use rustc_macros::HashStable; +use rustc_span::Span; +use std::borrow::Cow; +use std::fmt::{self, Debug, Formatter, Write}; +use std::iter; +use std::slice; + +pub use super::query::*; + +#[derive(Clone, TyEncodable, TyDecodable, HashStable, PartialEq)] +pub enum TerminatorKind<'tcx> { + /// Block should have one successor in the graph; we jump there. + Goto { target: BasicBlock }, + + /// Operand evaluates to an integer; jump depending on its value + /// to one of the targets, and otherwise fallback to `otherwise`. + SwitchInt { + /// The discriminant value being tested. + discr: Operand<'tcx>, + + /// The type of value being tested. + /// This is always the same as the type of `discr`. + /// FIXME: remove this redundant information. Currently, it is relied on by pretty-printing. + switch_ty: Ty<'tcx>, + + /// Possible values. The locations to branch to in each case + /// are found in the corresponding indices from the `targets` vector. + values: Cow<'tcx, [u128]>, + + /// Possible branch sites. The last element of this vector is used + /// for the otherwise branch, so targets.len() == values.len() + 1 + /// should hold. + // + // This invariant is quite non-obvious and also could be improved. + // One way to make this invariant is to have something like this instead: + // + // branches: Vec<(ConstInt, BasicBlock)>, + // otherwise: Option<BasicBlock> // exhaustive if None + // + // However we’ve decided to keep this as-is until we figure a case + // where some other approach seems to be strictly better than other. + targets: Vec<BasicBlock>, + }, + + /// Indicates that the landing pad is finished and unwinding should + /// continue. Emitted by `build::scope::diverge_cleanup`. + Resume, + + /// Indicates that the landing pad is finished and that the process + /// should abort. Used to prevent unwinding for foreign items. + Abort, + + /// Indicates a normal return. The return place should have + /// been filled in before this executes. This can occur multiple times + /// in different basic blocks. + Return, + + /// Indicates a terminator that can never be reached. + Unreachable, + + /// Drop the `Place`. + Drop { place: Place<'tcx>, target: BasicBlock, unwind: Option<BasicBlock> }, + + /// Drop the `Place` and assign the new value over it. This ensures + /// that the assignment to `P` occurs *even if* the destructor for + /// place unwinds. Its semantics are best explained by the + /// elaboration: + /// + /// ``` + /// BB0 { + /// DropAndReplace(P <- V, goto BB1, unwind BB2) + /// } + /// ``` + /// + /// becomes + /// + /// ``` + /// BB0 { + /// Drop(P, goto BB1, unwind BB2) + /// } + /// BB1 { + /// // P is now uninitialized + /// P <- V + /// } + /// BB2 { + /// // P is now uninitialized -- its dtor panicked + /// P <- V + /// } + /// ``` + DropAndReplace { + place: Place<'tcx>, + value: Operand<'tcx>, + target: BasicBlock, + unwind: Option<BasicBlock>, + }, + + /// Block ends with a call of a function. + Call { + /// The function that’s being called. + func: Operand<'tcx>, + /// Arguments the function is called with. + /// These are owned by the callee, which is free to modify them. + /// This allows the memory occupied by "by-value" arguments to be + /// reused across function calls without duplicating the contents. + args: Vec<Operand<'tcx>>, + /// Destination for the return value. If some, the call is converging. + destination: Option<(Place<'tcx>, BasicBlock)>, + /// Cleanups to be done if the call unwinds. + cleanup: Option<BasicBlock>, + /// `true` if this is from a call in HIR rather than from an overloaded + /// operator. True for overloaded function call. + from_hir_call: bool, + /// This `Span` is the span of the function, without the dot and receiver + /// (e.g. `foo(a, b)` in `x.foo(a, b)` + fn_span: Span, + }, + + /// Jump to the target if the condition has the expected value, + /// otherwise panic with a message and a cleanup target. + Assert { + cond: Operand<'tcx>, + expected: bool, + msg: AssertMessage<'tcx>, + target: BasicBlock, + cleanup: Option<BasicBlock>, + }, + + /// A suspend point. + Yield { + /// The value to return. + value: Operand<'tcx>, + /// Where to resume to. + resume: BasicBlock, + /// The place to store the resume argument in. + resume_arg: Place<'tcx>, + /// Cleanup to be done if the generator is dropped at this suspend point. + drop: Option<BasicBlock>, + }, + + /// Indicates the end of the dropping of a generator. + GeneratorDrop, + + /// A block where control flow only ever takes one real path, but borrowck + /// needs to be more conservative. + FalseEdge { + /// The target normal control flow will take. + real_target: BasicBlock, + /// A block control flow could conceptually jump to, but won't in + /// practice. + imaginary_target: BasicBlock, + }, + /// A terminator for blocks that only take one path in reality, but where we + /// reserve the right to unwind in borrowck, even if it won't happen in practice. + /// This can arise in infinite loops with no function calls for example. + FalseUnwind { + /// The target normal control flow will take. + real_target: BasicBlock, + /// The imaginary cleanup block link. This particular path will never be taken + /// in practice, but in order to avoid fragility we want to always + /// consider it in borrowck. We don't want to accept programs which + /// pass borrowck only when `panic=abort` or some assertions are disabled + /// due to release vs. debug mode builds. This needs to be an `Option` because + /// of the `remove_noop_landing_pads` and `no_landing_pads` passes. + unwind: Option<BasicBlock>, + }, + + /// Block ends with an inline assembly block. This is a terminator since + /// inline assembly is allowed to diverge. + InlineAsm { + /// The template for the inline assembly, with placeholders. + template: &'tcx [InlineAsmTemplatePiece], + + /// The operands for the inline assembly, as `Operand`s or `Place`s. + operands: Vec<InlineAsmOperand<'tcx>>, + + /// Miscellaneous options for the inline assembly. + options: InlineAsmOptions, + + /// Source spans for each line of the inline assembly code. These are + /// used to map assembler errors back to the line in the source code. + line_spans: &'tcx [Span], + + /// Destination block after the inline assembly returns, unless it is + /// diverging (InlineAsmOptions::NORETURN). + destination: Option<BasicBlock>, + }, +} +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct Terminator<'tcx> { + pub source_info: SourceInfo, + pub kind: TerminatorKind<'tcx>, +} + +impl<'tcx> Terminator<'tcx> { + pub fn successors(&self) -> Successors<'_> { + self.kind.successors() + } + + pub fn successors_mut(&mut self) -> SuccessorsMut<'_> { + self.kind.successors_mut() + } + + pub fn unwind(&self) -> Option<&Option<BasicBlock>> { + self.kind.unwind() + } + + pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> { + self.kind.unwind_mut() + } +} + +impl<'tcx> TerminatorKind<'tcx> { + pub fn if_( + tcx: TyCtxt<'tcx>, + cond: Operand<'tcx>, + t: BasicBlock, + f: BasicBlock, + ) -> TerminatorKind<'tcx> { + static BOOL_SWITCH_FALSE: &[u128] = &[0]; + TerminatorKind::SwitchInt { + discr: cond, + switch_ty: tcx.types.bool, + values: From::from(BOOL_SWITCH_FALSE), + targets: vec![f, t], + } + } + + pub fn successors(&self) -> Successors<'_> { + use self::TerminatorKind::*; + match *self { + Resume + | Abort + | GeneratorDrop + | Return + | Unreachable + | Call { destination: None, cleanup: None, .. } + | InlineAsm { destination: None, .. } => None.into_iter().chain(&[]), + Goto { target: ref t } + | Call { destination: None, cleanup: Some(ref t), .. } + | Call { destination: Some((_, ref t)), cleanup: None, .. } + | Yield { resume: ref t, drop: None, .. } + | DropAndReplace { target: ref t, unwind: None, .. } + | Drop { target: ref t, unwind: None, .. } + | Assert { target: ref t, cleanup: None, .. } + | FalseUnwind { real_target: ref t, unwind: None } + | InlineAsm { destination: Some(ref t), .. } => Some(t).into_iter().chain(&[]), + Call { destination: Some((_, ref t)), cleanup: Some(ref u), .. } + | Yield { resume: ref t, drop: Some(ref u), .. } + | DropAndReplace { target: ref t, unwind: Some(ref u), .. } + | Drop { target: ref t, unwind: Some(ref u), .. } + | Assert { target: ref t, cleanup: Some(ref u), .. } + | FalseUnwind { real_target: ref t, unwind: Some(ref u) } => { + Some(t).into_iter().chain(slice::from_ref(u)) + } + SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]), + FalseEdge { ref real_target, ref imaginary_target } => { + Some(real_target).into_iter().chain(slice::from_ref(imaginary_target)) + } + } + } + + pub fn successors_mut(&mut self) -> SuccessorsMut<'_> { + use self::TerminatorKind::*; + match *self { + Resume + | Abort + | GeneratorDrop + | Return + | Unreachable + | Call { destination: None, cleanup: None, .. } + | InlineAsm { destination: None, .. } => None.into_iter().chain(&mut []), + Goto { target: ref mut t } + | Call { destination: None, cleanup: Some(ref mut t), .. } + | Call { destination: Some((_, ref mut t)), cleanup: None, .. } + | Yield { resume: ref mut t, drop: None, .. } + | DropAndReplace { target: ref mut t, unwind: None, .. } + | Drop { target: ref mut t, unwind: None, .. } + | Assert { target: ref mut t, cleanup: None, .. } + | FalseUnwind { real_target: ref mut t, unwind: None } + | InlineAsm { destination: Some(ref mut t), .. } => Some(t).into_iter().chain(&mut []), + Call { destination: Some((_, ref mut t)), cleanup: Some(ref mut u), .. } + | Yield { resume: ref mut t, drop: Some(ref mut u), .. } + | DropAndReplace { target: ref mut t, unwind: Some(ref mut u), .. } + | Drop { target: ref mut t, unwind: Some(ref mut u), .. } + | Assert { target: ref mut t, cleanup: Some(ref mut u), .. } + | FalseUnwind { real_target: ref mut t, unwind: Some(ref mut u) } => { + Some(t).into_iter().chain(slice::from_mut(u)) + } + SwitchInt { ref mut targets, .. } => None.into_iter().chain(&mut targets[..]), + FalseEdge { ref mut real_target, ref mut imaginary_target } => { + Some(real_target).into_iter().chain(slice::from_mut(imaginary_target)) + } + } + } + + pub fn unwind(&self) -> Option<&Option<BasicBlock>> { + match *self { + TerminatorKind::Goto { .. } + | TerminatorKind::Resume + | TerminatorKind::Abort + | TerminatorKind::Return + | TerminatorKind::Unreachable + | TerminatorKind::GeneratorDrop + | TerminatorKind::Yield { .. } + | TerminatorKind::SwitchInt { .. } + | TerminatorKind::FalseEdge { .. } + | TerminatorKind::InlineAsm { .. } => None, + TerminatorKind::Call { cleanup: ref unwind, .. } + | TerminatorKind::Assert { cleanup: ref unwind, .. } + | TerminatorKind::DropAndReplace { ref unwind, .. } + | TerminatorKind::Drop { ref unwind, .. } + | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind), + } + } + + pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> { + match *self { + TerminatorKind::Goto { .. } + | TerminatorKind::Resume + | TerminatorKind::Abort + | TerminatorKind::Return + | TerminatorKind::Unreachable + | TerminatorKind::GeneratorDrop + | TerminatorKind::Yield { .. } + | TerminatorKind::SwitchInt { .. } + | TerminatorKind::FalseEdge { .. } + | TerminatorKind::InlineAsm { .. } => None, + TerminatorKind::Call { cleanup: ref mut unwind, .. } + | TerminatorKind::Assert { cleanup: ref mut unwind, .. } + | TerminatorKind::DropAndReplace { ref mut unwind, .. } + | TerminatorKind::Drop { ref mut unwind, .. } + | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind), + } + } +} + +impl<'tcx> Debug for TerminatorKind<'tcx> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + self.fmt_head(fmt)?; + let successor_count = self.successors().count(); + let labels = self.fmt_successor_labels(); + assert_eq!(successor_count, labels.len()); + + match successor_count { + 0 => Ok(()), + + 1 => write!(fmt, " -> {:?}", self.successors().next().unwrap()), + + _ => { + write!(fmt, " -> [")?; + for (i, target) in self.successors().enumerate() { + if i > 0 { + write!(fmt, ", ")?; + } + write!(fmt, "{}: {:?}", labels[i], target)?; + } + write!(fmt, "]") + } + } + } +} + +impl<'tcx> TerminatorKind<'tcx> { + /// Writes the "head" part of the terminator; that is, its name and the data it uses to pick the + /// successor basic block, if any. The only information not included is the list of possible + /// successors, which may be rendered differently between the text and the graphviz format. + pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result { + use self::TerminatorKind::*; + match self { + Goto { .. } => write!(fmt, "goto"), + SwitchInt { discr, .. } => write!(fmt, "switchInt({:?})", discr), + Return => write!(fmt, "return"), + GeneratorDrop => write!(fmt, "generator_drop"), + Resume => write!(fmt, "resume"), + Abort => write!(fmt, "abort"), + Yield { value, resume_arg, .. } => write!(fmt, "{:?} = yield({:?})", resume_arg, value), + Unreachable => write!(fmt, "unreachable"), + Drop { place, .. } => write!(fmt, "drop({:?})", place), + DropAndReplace { place, value, .. } => { + write!(fmt, "replace({:?} <- {:?})", place, value) + } + Call { func, args, destination, .. } => { + if let Some((destination, _)) = destination { + write!(fmt, "{:?} = ", destination)?; + } + write!(fmt, "{:?}(", func)?; + for (index, arg) in args.iter().enumerate() { + if index > 0 { + write!(fmt, ", ")?; + } + write!(fmt, "{:?}", arg)?; + } + write!(fmt, ")") + } + Assert { cond, expected, msg, .. } => { + write!(fmt, "assert(")?; + if !expected { + write!(fmt, "!")?; + } + write!(fmt, "{:?}, ", cond)?; + msg.fmt_assert_args(fmt)?; + write!(fmt, ")") + } + FalseEdge { .. } => write!(fmt, "falseEdge"), + FalseUnwind { .. } => write!(fmt, "falseUnwind"), + InlineAsm { template, ref operands, options, .. } => { + write!(fmt, "asm!(\"{}\"", InlineAsmTemplatePiece::to_string(template))?; + for op in operands { + write!(fmt, ", ")?; + let print_late = |&late| if late { "late" } else { "" }; + match op { + InlineAsmOperand::In { reg, value } => { + write!(fmt, "in({}) {:?}", reg, value)?; + } + InlineAsmOperand::Out { reg, late, place: Some(place) } => { + write!(fmt, "{}out({}) {:?}", print_late(late), reg, place)?; + } + InlineAsmOperand::Out { reg, late, place: None } => { + write!(fmt, "{}out({}) _", print_late(late), reg)?; + } + InlineAsmOperand::InOut { + reg, + late, + in_value, + out_place: Some(out_place), + } => { + write!( + fmt, + "in{}out({}) {:?} => {:?}", + print_late(late), + reg, + in_value, + out_place + )?; + } + InlineAsmOperand::InOut { reg, late, in_value, out_place: None } => { + write!(fmt, "in{}out({}) {:?} => _", print_late(late), reg, in_value)?; + } + InlineAsmOperand::Const { value } => { + write!(fmt, "const {:?}", value)?; + } + InlineAsmOperand::SymFn { value } => { + write!(fmt, "sym_fn {:?}", value)?; + } + InlineAsmOperand::SymStatic { def_id } => { + write!(fmt, "sym_static {:?}", def_id)?; + } + } + } + write!(fmt, ", options({:?}))", options) + } + } + } + + /// Returns the list of labels for the edges to the successor basic blocks. + pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> { + use self::TerminatorKind::*; + match *self { + Return | Resume | Abort | Unreachable | GeneratorDrop => vec![], + Goto { .. } => vec!["".into()], + SwitchInt { ref values, switch_ty, .. } => ty::tls::with(|tcx| { + let param_env = ty::ParamEnv::empty(); + let switch_ty = tcx.lift(&switch_ty).unwrap(); + let size = tcx.layout_of(param_env.and(switch_ty)).unwrap().size; + values + .iter() + .map(|&u| { + ty::Const::from_scalar(tcx, Scalar::from_uint(u, size), switch_ty) + .to_string() + .into() + }) + .chain(iter::once("otherwise".into())) + .collect() + }), + Call { destination: Some(_), cleanup: Some(_), .. } => { + vec!["return".into(), "unwind".into()] + } + Call { destination: Some(_), cleanup: None, .. } => vec!["return".into()], + Call { destination: None, cleanup: Some(_), .. } => vec!["unwind".into()], + Call { destination: None, cleanup: None, .. } => vec![], + Yield { drop: Some(_), .. } => vec!["resume".into(), "drop".into()], + Yield { drop: None, .. } => vec!["resume".into()], + DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => { + vec!["return".into()] + } + DropAndReplace { unwind: Some(_), .. } | Drop { unwind: Some(_), .. } => { + vec!["return".into(), "unwind".into()] + } + Assert { cleanup: None, .. } => vec!["".into()], + Assert { .. } => vec!["success".into(), "unwind".into()], + FalseEdge { .. } => vec!["real".into(), "imaginary".into()], + FalseUnwind { unwind: Some(_), .. } => vec!["real".into(), "cleanup".into()], + FalseUnwind { unwind: None, .. } => vec!["real".into()], + InlineAsm { destination: Some(_), .. } => vec!["".into()], + InlineAsm { destination: None, .. } => vec![], + } + } +} diff --git a/compiler/rustc_middle/src/mir/traversal.rs b/compiler/rustc_middle/src/mir/traversal.rs new file mode 100644 index 00000000000..36e277d1a88 --- /dev/null +++ b/compiler/rustc_middle/src/mir/traversal.rs @@ -0,0 +1,311 @@ +use rustc_index::bit_set::BitSet; + +use super::*; + +/// Preorder traversal of a graph. +/// +/// Preorder traversal is when each node is visited before any of its +/// successors +/// +/// ```text +/// +/// A +/// / \ +/// / \ +/// B C +/// \ / +/// \ / +/// D +/// ``` +/// +/// A preorder traversal of this graph is either `A B D C` or `A C D B` +#[derive(Clone)] +pub struct Preorder<'a, 'tcx> { + body: &'a Body<'tcx>, + visited: BitSet<BasicBlock>, + worklist: Vec<BasicBlock>, + root_is_start_block: bool, +} + +impl<'a, 'tcx> Preorder<'a, 'tcx> { + pub fn new(body: &'a Body<'tcx>, root: BasicBlock) -> Preorder<'a, 'tcx> { + let worklist = vec![root]; + + Preorder { + body, + visited: BitSet::new_empty(body.basic_blocks().len()), + worklist, + root_is_start_block: root == START_BLOCK, + } + } +} + +pub fn preorder<'a, 'tcx>(body: &'a Body<'tcx>) -> Preorder<'a, 'tcx> { + Preorder::new(body, START_BLOCK) +} + +impl<'a, 'tcx> Iterator for Preorder<'a, 'tcx> { + type Item = (BasicBlock, &'a BasicBlockData<'tcx>); + + fn next(&mut self) -> Option<(BasicBlock, &'a BasicBlockData<'tcx>)> { + while let Some(idx) = self.worklist.pop() { + if !self.visited.insert(idx) { + continue; + } + + let data = &self.body[idx]; + + if let Some(ref term) = data.terminator { + self.worklist.extend(term.successors()); + } + + return Some((idx, data)); + } + + None + } + + fn size_hint(&self) -> (usize, Option<usize>) { + // All the blocks, minus the number of blocks we've visited. + let upper = self.body.basic_blocks().len() - self.visited.count(); + + let lower = if self.root_is_start_block { + // We will visit all remaining blocks exactly once. + upper + } else { + self.worklist.len() + }; + + (lower, Some(upper)) + } +} + +/// Postorder traversal of a graph. +/// +/// Postorder traversal is when each node is visited after all of its +/// successors, except when the successor is only reachable by a back-edge +/// +/// +/// ```text +/// +/// A +/// / \ +/// / \ +/// B C +/// \ / +/// \ / +/// D +/// ``` +/// +/// A Postorder traversal of this graph is `D B C A` or `D C B A` +pub struct Postorder<'a, 'tcx> { + body: &'a Body<'tcx>, + visited: BitSet<BasicBlock>, + visit_stack: Vec<(BasicBlock, Successors<'a>)>, + root_is_start_block: bool, +} + +impl<'a, 'tcx> Postorder<'a, 'tcx> { + pub fn new(body: &'a Body<'tcx>, root: BasicBlock) -> Postorder<'a, 'tcx> { + let mut po = Postorder { + body, + visited: BitSet::new_empty(body.basic_blocks().len()), + visit_stack: Vec::new(), + root_is_start_block: root == START_BLOCK, + }; + + let data = &po.body[root]; + + if let Some(ref term) = data.terminator { + po.visited.insert(root); + po.visit_stack.push((root, term.successors())); + po.traverse_successor(); + } + + po + } + + fn traverse_successor(&mut self) { + // This is quite a complex loop due to 1. the borrow checker not liking it much + // and 2. what exactly is going on is not clear + // + // It does the actual traversal of the graph, while the `next` method on the iterator + // just pops off of the stack. `visit_stack` is a stack containing pairs of nodes and + // iterators over the successors of those nodes. Each iteration attempts to get the next + // node from the top of the stack, then pushes that node and an iterator over the + // successors to the top of the stack. This loop only grows `visit_stack`, stopping when + // we reach a child that has no children that we haven't already visited. + // + // For a graph that looks like this: + // + // A + // / \ + // / \ + // B C + // | | + // | | + // D | + // \ / + // \ / + // E + // + // The state of the stack starts out with just the root node (`A` in this case); + // [(A, [B, C])] + // + // When the first call to `traverse_successor` happens, the following happens: + // + // [(B, [D]), // `B` taken from the successors of `A`, pushed to the + // // top of the stack along with the successors of `B` + // (A, [C])] + // + // [(D, [E]), // `D` taken from successors of `B`, pushed to stack + // (B, []), + // (A, [C])] + // + // [(E, []), // `E` taken from successors of `D`, pushed to stack + // (D, []), + // (B, []), + // (A, [C])] + // + // Now that the top of the stack has no successors we can traverse, each item will + // be popped off during iteration until we get back to `A`. This yields [E, D, B]. + // + // When we yield `B` and call `traverse_successor`, we push `C` to the stack, but + // since we've already visited `E`, that child isn't added to the stack. The last + // two iterations yield `C` and finally `A` for a final traversal of [E, D, B, C, A] + loop { + let bb = if let Some(&mut (_, ref mut iter)) = self.visit_stack.last_mut() { + if let Some(&bb) = iter.next() { + bb + } else { + break; + } + } else { + break; + }; + + if self.visited.insert(bb) { + if let Some(term) = &self.body[bb].terminator { + self.visit_stack.push((bb, term.successors())); + } + } + } + } +} + +pub fn postorder<'a, 'tcx>(body: &'a Body<'tcx>) -> Postorder<'a, 'tcx> { + Postorder::new(body, START_BLOCK) +} + +impl<'a, 'tcx> Iterator for Postorder<'a, 'tcx> { + type Item = (BasicBlock, &'a BasicBlockData<'tcx>); + + fn next(&mut self) -> Option<(BasicBlock, &'a BasicBlockData<'tcx>)> { + let next = self.visit_stack.pop(); + if next.is_some() { + self.traverse_successor(); + } + + next.map(|(bb, _)| (bb, &self.body[bb])) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + // All the blocks, minus the number of blocks we've visited. + let upper = self.body.basic_blocks().len() - self.visited.count(); + + let lower = if self.root_is_start_block { + // We will visit all remaining blocks exactly once. + upper + } else { + self.visit_stack.len() + }; + + (lower, Some(upper)) + } +} + +/// Reverse postorder traversal of a graph +/// +/// Reverse postorder is the reverse order of a postorder traversal. +/// This is different to a preorder traversal and represents a natural +/// linearization of control-flow. +/// +/// ```text +/// +/// A +/// / \ +/// / \ +/// B C +/// \ / +/// \ / +/// D +/// ``` +/// +/// A reverse postorder traversal of this graph is either `A B C D` or `A C B D` +/// Note that for a graph containing no loops (i.e., A DAG), this is equivalent to +/// a topological sort. +/// +/// Construction of a `ReversePostorder` traversal requires doing a full +/// postorder traversal of the graph, therefore this traversal should be +/// constructed as few times as possible. Use the `reset` method to be able +/// to re-use the traversal +#[derive(Clone)] +pub struct ReversePostorder<'a, 'tcx> { + body: &'a Body<'tcx>, + blocks: Vec<BasicBlock>, + idx: usize, +} + +impl<'a, 'tcx> ReversePostorder<'a, 'tcx> { + pub fn new(body: &'a Body<'tcx>, root: BasicBlock) -> ReversePostorder<'a, 'tcx> { + let blocks: Vec<_> = Postorder::new(body, root).map(|(bb, _)| bb).collect(); + + let len = blocks.len(); + + ReversePostorder { body, blocks, idx: len } + } + + pub fn reset(&mut self) { + self.idx = self.blocks.len(); + } +} + +pub fn reverse_postorder<'a, 'tcx>(body: &'a Body<'tcx>) -> ReversePostorder<'a, 'tcx> { + ReversePostorder::new(body, START_BLOCK) +} + +impl<'a, 'tcx> Iterator for ReversePostorder<'a, 'tcx> { + type Item = (BasicBlock, &'a BasicBlockData<'tcx>); + + fn next(&mut self) -> Option<(BasicBlock, &'a BasicBlockData<'tcx>)> { + if self.idx == 0 { + return None; + } + self.idx -= 1; + + self.blocks.get(self.idx).map(|&bb| (bb, &self.body[bb])) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (self.idx, Some(self.idx)) + } +} + +impl<'a, 'tcx> ExactSizeIterator for ReversePostorder<'a, 'tcx> {} + +/// Returns an iterator over all basic blocks reachable from the `START_BLOCK` in no particular +/// order. +/// +/// This is clearer than writing `preorder` in cases where the order doesn't matter. +pub fn reachable<'a, 'tcx>( + body: &'a Body<'tcx>, +) -> impl 'a + Iterator<Item = (BasicBlock, &'a BasicBlockData<'tcx>)> { + preorder(body) +} + +/// Returns a `BitSet` containing all basic blocks reachable from the `START_BLOCK`. +pub fn reachable_as_bitset(body: &Body<'tcx>) -> BitSet<BasicBlock> { + let mut iter = preorder(body); + (&mut iter).for_each(drop); + iter.visited +} diff --git a/compiler/rustc_middle/src/mir/type_foldable.rs b/compiler/rustc_middle/src/mir/type_foldable.rs new file mode 100644 index 00000000000..6bb6abe0289 --- /dev/null +++ b/compiler/rustc_middle/src/mir/type_foldable.rs @@ -0,0 +1,331 @@ +//! `TypeFoldable` implementations for MIR types + +use super::*; +use crate::ty; + +CloneTypeFoldableAndLiftImpls! { + BlockTailInfo, + MirPhase, + SourceInfo, + FakeReadCause, + RetagKind, + SourceScope, + SourceScopeData, + SourceScopeLocalData, + UserTypeAnnotationIndex, +} + +impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + use crate::mir::TerminatorKind::*; + + let kind = match self.kind { + Goto { target } => Goto { target }, + SwitchInt { ref discr, switch_ty, ref values, ref targets } => SwitchInt { + discr: discr.fold_with(folder), + switch_ty: switch_ty.fold_with(folder), + values: values.clone(), + targets: targets.clone(), + }, + Drop { ref place, target, unwind } => { + Drop { place: place.fold_with(folder), target, unwind } + } + DropAndReplace { ref place, ref value, target, unwind } => DropAndReplace { + place: place.fold_with(folder), + value: value.fold_with(folder), + target, + unwind, + }, + Yield { ref value, resume, ref resume_arg, drop } => Yield { + value: value.fold_with(folder), + resume, + resume_arg: resume_arg.fold_with(folder), + drop, + }, + Call { ref func, ref args, ref destination, cleanup, from_hir_call, fn_span } => { + let dest = + destination.as_ref().map(|&(ref loc, dest)| (loc.fold_with(folder), dest)); + + Call { + func: func.fold_with(folder), + args: args.fold_with(folder), + destination: dest, + cleanup, + from_hir_call, + fn_span, + } + } + Assert { ref cond, expected, ref msg, target, cleanup } => { + use AssertKind::*; + let msg = match msg { + BoundsCheck { len, index } => { + BoundsCheck { len: len.fold_with(folder), index: index.fold_with(folder) } + } + Overflow(op, l, r) => Overflow(*op, l.fold_with(folder), r.fold_with(folder)), + OverflowNeg(op) => OverflowNeg(op.fold_with(folder)), + DivisionByZero(op) => DivisionByZero(op.fold_with(folder)), + RemainderByZero(op) => RemainderByZero(op.fold_with(folder)), + ResumedAfterReturn(_) | ResumedAfterPanic(_) => msg.clone(), + }; + Assert { cond: cond.fold_with(folder), expected, msg, target, cleanup } + } + GeneratorDrop => GeneratorDrop, + Resume => Resume, + Abort => Abort, + Return => Return, + Unreachable => Unreachable, + FalseEdge { real_target, imaginary_target } => { + FalseEdge { real_target, imaginary_target } + } + FalseUnwind { real_target, unwind } => FalseUnwind { real_target, unwind }, + InlineAsm { template, ref operands, options, line_spans, destination } => InlineAsm { + template, + operands: operands.fold_with(folder), + options, + line_spans, + destination, + }, + }; + Terminator { source_info: self.source_info, kind } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + use crate::mir::TerminatorKind::*; + + match self.kind { + SwitchInt { ref discr, switch_ty, .. } => { + discr.visit_with(visitor) || switch_ty.visit_with(visitor) + } + Drop { ref place, .. } => place.visit_with(visitor), + DropAndReplace { ref place, ref value, .. } => { + place.visit_with(visitor) || value.visit_with(visitor) + } + Yield { ref value, .. } => value.visit_with(visitor), + Call { ref func, ref args, ref destination, .. } => { + let dest = if let Some((ref loc, _)) = *destination { + loc.visit_with(visitor) + } else { + false + }; + dest || func.visit_with(visitor) || args.visit_with(visitor) + } + Assert { ref cond, ref msg, .. } => { + if cond.visit_with(visitor) { + use AssertKind::*; + match msg { + BoundsCheck { ref len, ref index } => { + len.visit_with(visitor) || index.visit_with(visitor) + } + Overflow(_, l, r) => l.visit_with(visitor) || r.visit_with(visitor), + OverflowNeg(op) | DivisionByZero(op) | RemainderByZero(op) => { + op.visit_with(visitor) + } + ResumedAfterReturn(_) | ResumedAfterPanic(_) => false, + } + } else { + false + } + } + InlineAsm { ref operands, .. } => operands.visit_with(visitor), + Goto { .. } + | Resume + | Abort + | Return + | GeneratorDrop + | Unreachable + | FalseEdge { .. } + | FalseUnwind { .. } => false, + } + } +} + +impl<'tcx> TypeFoldable<'tcx> for GeneratorKind { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self { + *self + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool { + false + } +} + +impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + Place { local: self.local.fold_with(folder), projection: self.projection.fold_with(folder) } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.local.visit_with(visitor) || self.projection.visit_with(visitor) + } +} + +impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<PlaceElem<'tcx>> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + let v = self.iter().map(|t| t.fold_with(folder)).collect::<Vec<_>>(); + folder.tcx().intern_place_elems(&v) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|t| t.visit_with(visitor)) + } +} + +impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + use crate::mir::Rvalue::*; + match *self { + Use(ref op) => Use(op.fold_with(folder)), + Repeat(ref op, len) => Repeat(op.fold_with(folder), len), + ThreadLocalRef(did) => ThreadLocalRef(did.fold_with(folder)), + Ref(region, bk, ref place) => { + Ref(region.fold_with(folder), bk, place.fold_with(folder)) + } + AddressOf(mutability, ref place) => AddressOf(mutability, place.fold_with(folder)), + Len(ref place) => Len(place.fold_with(folder)), + Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)), + BinaryOp(op, ref rhs, ref lhs) => { + BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder)) + } + CheckedBinaryOp(op, ref rhs, ref lhs) => { + CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder)) + } + UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)), + Discriminant(ref place) => Discriminant(place.fold_with(folder)), + NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)), + Aggregate(ref kind, ref fields) => { + let kind = box match **kind { + AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)), + AggregateKind::Tuple => AggregateKind::Tuple, + AggregateKind::Adt(def, v, substs, user_ty, n) => AggregateKind::Adt( + def, + v, + substs.fold_with(folder), + user_ty.fold_with(folder), + n, + ), + AggregateKind::Closure(id, substs) => { + AggregateKind::Closure(id, substs.fold_with(folder)) + } + AggregateKind::Generator(id, substs, movablity) => { + AggregateKind::Generator(id, substs.fold_with(folder), movablity) + } + }; + Aggregate(kind, fields.fold_with(folder)) + } + } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + use crate::mir::Rvalue::*; + match *self { + Use(ref op) => op.visit_with(visitor), + Repeat(ref op, _) => op.visit_with(visitor), + ThreadLocalRef(did) => did.visit_with(visitor), + Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor), + AddressOf(_, ref place) => place.visit_with(visitor), + Len(ref place) => place.visit_with(visitor), + Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor), + BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => { + rhs.visit_with(visitor) || lhs.visit_with(visitor) + } + UnaryOp(_, ref val) => val.visit_with(visitor), + Discriminant(ref place) => place.visit_with(visitor), + NullaryOp(_, ty) => ty.visit_with(visitor), + Aggregate(ref kind, ref fields) => { + (match **kind { + AggregateKind::Array(ty) => ty.visit_with(visitor), + AggregateKind::Tuple => false, + AggregateKind::Adt(_, _, substs, user_ty, _) => { + substs.visit_with(visitor) || user_ty.visit_with(visitor) + } + AggregateKind::Closure(_, substs) => substs.visit_with(visitor), + AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor), + }) || fields.visit_with(visitor) + } + } + } +} + +impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + match *self { + Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)), + Operand::Move(ref place) => Operand::Move(place.fold_with(folder)), + Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)), + } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + match *self { + Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor), + Operand::Constant(ref c) => c.visit_with(visitor), + } + } +} + +impl<'tcx> TypeFoldable<'tcx> for PlaceElem<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + use crate::mir::ProjectionElem::*; + + match *self { + Deref => Deref, + Field(f, ty) => Field(f, ty.fold_with(folder)), + Index(v) => Index(v.fold_with(folder)), + Downcast(symbol, variantidx) => Downcast(symbol, variantidx), + ConstantIndex { offset, min_length, from_end } => { + ConstantIndex { offset, min_length, from_end } + } + Subslice { from, to, from_end } => Subslice { from, to, from_end }, + } + } + + fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool { + use crate::mir::ProjectionElem::*; + + match self { + Field(_, ty) => ty.visit_with(visitor), + Index(v) => v.visit_with(visitor), + _ => false, + } + } +} + +impl<'tcx> TypeFoldable<'tcx> for Field { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self { + *self + } + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool { + false + } +} + +impl<'tcx> TypeFoldable<'tcx> for GeneratorSavedLocal { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self { + *self + } + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool { + false + } +} + +impl<'tcx, R: Idx, C: Idx> TypeFoldable<'tcx> for BitMatrix<R, C> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self { + self.clone() + } + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool { + false + } +} + +impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + Constant { + span: self.span, + user_ty: self.user_ty.fold_with(folder), + literal: self.literal.fold_with(folder), + } + } + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.literal.visit_with(visitor) + } +} diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs new file mode 100644 index 00000000000..6515ae31b46 --- /dev/null +++ b/compiler/rustc_middle/src/mir/visit.rs @@ -0,0 +1,1247 @@ +use crate::mir::*; +use crate::ty::subst::SubstsRef; +use crate::ty::{CanonicalUserTypeAnnotation, Ty}; +use rustc_span::Span; + +// # The MIR Visitor +// +// ## Overview +// +// There are two visitors, one for immutable and one for mutable references, +// but both are generated by the following macro. The code is written according +// to the following conventions: +// +// - introduce a `visit_foo` and a `super_foo` method for every MIR type +// - `visit_foo`, by default, calls `super_foo` +// - `super_foo`, by default, destructures the `foo` and calls `visit_foo` +// +// This allows you as a user to override `visit_foo` for types are +// interested in, and invoke (within that method) call +// `self.super_foo` to get the default behavior. Just as in an OO +// language, you should never call `super` methods ordinarily except +// in that circumstance. +// +// For the most part, we do not destructure things external to the +// MIR, e.g., types, spans, etc, but simply visit them and stop. This +// avoids duplication with other visitors like `TypeFoldable`. +// +// ## Updating +// +// The code is written in a very deliberate style intended to minimize +// the chance of things being overlooked. You'll notice that we always +// use pattern matching to reference fields and we ensure that all +// matches are exhaustive. +// +// For example, the `super_basic_block_data` method begins like this: +// +// ```rust +// fn super_basic_block_data(&mut self, +// block: BasicBlock, +// data: & $($mutability)? BasicBlockData<'tcx>) { +// let BasicBlockData { +// statements, +// terminator, +// is_cleanup: _ +// } = *data; +// +// for statement in statements { +// self.visit_statement(block, statement); +// } +// +// ... +// } +// ``` +// +// Here we used `let BasicBlockData { <fields> } = *data` deliberately, +// rather than writing `data.statements` in the body. This is because if one +// adds a new field to `BasicBlockData`, one will be forced to revise this code, +// and hence one will (hopefully) invoke the correct visit methods (if any). +// +// For this to work, ALL MATCHES MUST BE EXHAUSTIVE IN FIELDS AND VARIANTS. +// That means you never write `..` to skip over fields, nor do you write `_` +// to skip over variants in a `match`. +// +// The only place that `_` is acceptable is to match a field (or +// variant argument) that does not require visiting, as in +// `is_cleanup` above. + +macro_rules! make_mir_visitor { + ($visitor_trait_name:ident, $($mutability:ident)?) => { + pub trait $visitor_trait_name<'tcx> { + // Override these, and call `self.super_xxx` to revert back to the + // default behavior. + + fn visit_body( + &mut self, + body: &$($mutability)? Body<'tcx>, + ) { + self.super_body(body); + } + + fn visit_basic_block_data(&mut self, + block: BasicBlock, + data: & $($mutability)? BasicBlockData<'tcx>) { + self.super_basic_block_data(block, data); + } + + fn visit_source_scope_data(&mut self, + scope_data: & $($mutability)? SourceScopeData) { + self.super_source_scope_data(scope_data); + } + + fn visit_statement(&mut self, + statement: & $($mutability)? Statement<'tcx>, + location: Location) { + self.super_statement(statement, location); + } + + fn visit_assign(&mut self, + place: & $($mutability)? Place<'tcx>, + rvalue: & $($mutability)? Rvalue<'tcx>, + location: Location) { + self.super_assign(place, rvalue, location); + } + + fn visit_terminator(&mut self, + terminator: & $($mutability)? Terminator<'tcx>, + location: Location) { + self.super_terminator(terminator, location); + } + + fn visit_assert_message(&mut self, + msg: & $($mutability)? AssertMessage<'tcx>, + location: Location) { + self.super_assert_message(msg, location); + } + + fn visit_rvalue(&mut self, + rvalue: & $($mutability)? Rvalue<'tcx>, + location: Location) { + self.super_rvalue(rvalue, location); + } + + fn visit_operand(&mut self, + operand: & $($mutability)? Operand<'tcx>, + location: Location) { + self.super_operand(operand, location); + } + + fn visit_ascribe_user_ty(&mut self, + place: & $($mutability)? Place<'tcx>, + variance: & $($mutability)? ty::Variance, + user_ty: & $($mutability)? UserTypeProjection, + location: Location) { + self.super_ascribe_user_ty(place, variance, user_ty, location); + } + + fn visit_coverage(&mut self, + coverage: & $($mutability)? Coverage, + location: Location) { + self.super_coverage(coverage, location); + } + + fn visit_retag(&mut self, + kind: & $($mutability)? RetagKind, + place: & $($mutability)? Place<'tcx>, + location: Location) { + self.super_retag(kind, place, location); + } + + fn visit_place(&mut self, + place: & $($mutability)? Place<'tcx>, + context: PlaceContext, + location: Location) { + self.super_place(place, context, location); + } + + visit_place_fns!($($mutability)?); + + fn visit_constant(&mut self, + constant: & $($mutability)? Constant<'tcx>, + location: Location) { + self.super_constant(constant, location); + } + + fn visit_span(&mut self, + span: & $($mutability)? Span) { + self.super_span(span); + } + + fn visit_source_info(&mut self, + source_info: & $($mutability)? SourceInfo) { + self.super_source_info(source_info); + } + + fn visit_ty(&mut self, + ty: $(& $mutability)? Ty<'tcx>, + _: TyContext) { + self.super_ty(ty); + } + + fn visit_user_type_projection( + &mut self, + ty: & $($mutability)? UserTypeProjection, + ) { + self.super_user_type_projection(ty); + } + + fn visit_user_type_annotation( + &mut self, + index: UserTypeAnnotationIndex, + ty: & $($mutability)? CanonicalUserTypeAnnotation<'tcx>, + ) { + self.super_user_type_annotation(index, ty); + } + + fn visit_region(&mut self, + region: & $($mutability)? ty::Region<'tcx>, + _: Location) { + self.super_region(region); + } + + fn visit_const(&mut self, + constant: & $($mutability)? &'tcx ty::Const<'tcx>, + _: Location) { + self.super_const(constant); + } + + fn visit_substs(&mut self, + substs: & $($mutability)? SubstsRef<'tcx>, + _: Location) { + self.super_substs(substs); + } + + fn visit_local_decl(&mut self, + local: Local, + local_decl: & $($mutability)? LocalDecl<'tcx>) { + self.super_local_decl(local, local_decl); + } + + fn visit_var_debug_info(&mut self, + var_debug_info: & $($mutability)* VarDebugInfo<'tcx>) { + self.super_var_debug_info(var_debug_info); + } + + fn visit_local(&mut self, + _local: & $($mutability)? Local, + _context: PlaceContext, + _location: Location) { + } + + fn visit_source_scope(&mut self, + scope: & $($mutability)? SourceScope) { + self.super_source_scope(scope); + } + + // The `super_xxx` methods comprise the default behavior and are + // not meant to be overridden. + + fn super_body( + &mut self, + body: &$($mutability)? Body<'tcx>, + ) { + let span = body.span; + if let Some(yield_ty) = &$($mutability)? body.yield_ty { + self.visit_ty( + yield_ty, + TyContext::YieldTy(SourceInfo::outermost(span)) + ); + } + + // for best performance, we want to use an iterator rather + // than a for-loop, to avoid calling `body::Body::invalidate` for + // each basic block. + macro_rules! basic_blocks { + (mut) => (body.basic_blocks_mut().iter_enumerated_mut()); + () => (body.basic_blocks().iter_enumerated()); + }; + for (bb, data) in basic_blocks!($($mutability)?) { + self.visit_basic_block_data(bb, data); + } + + for scope in &$($mutability)? body.source_scopes { + self.visit_source_scope_data(scope); + } + + self.visit_ty( + &$($mutability)? body.return_ty(), + TyContext::ReturnTy(SourceInfo::outermost(body.span)) + ); + + for local in body.local_decls.indices() { + self.visit_local_decl(local, & $($mutability)? body.local_decls[local]); + } + + macro_rules! type_annotations { + (mut) => (body.user_type_annotations.iter_enumerated_mut()); + () => (body.user_type_annotations.iter_enumerated()); + }; + + for (index, annotation) in type_annotations!($($mutability)?) { + self.visit_user_type_annotation( + index, annotation + ); + } + + for var_debug_info in &$($mutability)? body.var_debug_info { + self.visit_var_debug_info(var_debug_info); + } + + self.visit_span(&$($mutability)? body.span); + + for const_ in &$($mutability)? body.required_consts { + let location = START_BLOCK.start_location(); + self.visit_constant(const_, location); + } + } + + fn super_basic_block_data(&mut self, + block: BasicBlock, + data: & $($mutability)? BasicBlockData<'tcx>) { + let BasicBlockData { + statements, + terminator, + is_cleanup: _ + } = data; + + let mut index = 0; + for statement in statements { + let location = Location { block: block, statement_index: index }; + self.visit_statement(statement, location); + index += 1; + } + + if let Some(terminator) = terminator { + let location = Location { block: block, statement_index: index }; + self.visit_terminator(terminator, location); + } + } + + fn super_source_scope_data(&mut self, scope_data: & $($mutability)? SourceScopeData) { + let SourceScopeData { + span, + parent_scope, + local_data: _, + } = scope_data; + + self.visit_span(span); + if let Some(parent_scope) = parent_scope { + self.visit_source_scope(parent_scope); + } + } + + fn super_statement(&mut self, + statement: & $($mutability)? Statement<'tcx>, + location: Location) { + let Statement { + source_info, + kind, + } = statement; + + self.visit_source_info(source_info); + match kind { + StatementKind::Assign( + box(ref $($mutability)? place, ref $($mutability)? rvalue) + ) => { + self.visit_assign(place, rvalue, location); + } + StatementKind::FakeRead(_, place) => { + self.visit_place( + place, + PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect), + location + ); + } + StatementKind::SetDiscriminant { place, .. } => { + self.visit_place( + place, + PlaceContext::MutatingUse(MutatingUseContext::Store), + location + ); + } + StatementKind::StorageLive(local) => { + self.visit_local( + local, + PlaceContext::NonUse(NonUseContext::StorageLive), + location + ); + } + StatementKind::StorageDead(local) => { + self.visit_local( + local, + PlaceContext::NonUse(NonUseContext::StorageDead), + location + ); + } + StatementKind::LlvmInlineAsm(asm) => { + for output in & $($mutability)? asm.outputs[..] { + self.visit_place( + output, + PlaceContext::MutatingUse(MutatingUseContext::AsmOutput), + location + ); + } + for (span, input) in & $($mutability)? asm.inputs[..] { + self.visit_span(span); + self.visit_operand(input, location); + } + } + StatementKind::Retag(kind, place) => { + self.visit_retag(kind, place, location); + } + StatementKind::AscribeUserType( + box(ref $($mutability)? place, ref $($mutability)? user_ty), + variance + ) => { + self.visit_ascribe_user_ty(place, variance, user_ty, location); + } + StatementKind::Coverage(coverage) => { + self.visit_coverage( + coverage, + location + ) + } + StatementKind::Nop => {} + } + } + + fn super_assign(&mut self, + place: &$($mutability)? Place<'tcx>, + rvalue: &$($mutability)? Rvalue<'tcx>, + location: Location) { + self.visit_place( + place, + PlaceContext::MutatingUse(MutatingUseContext::Store), + location + ); + self.visit_rvalue(rvalue, location); + } + + fn super_terminator(&mut self, + terminator: &$($mutability)? Terminator<'tcx>, + location: Location) { + let Terminator { source_info, kind } = terminator; + + self.visit_source_info(source_info); + match kind { + TerminatorKind::Goto { .. } | + TerminatorKind::Resume | + TerminatorKind::Abort | + TerminatorKind::GeneratorDrop | + TerminatorKind::Unreachable | + TerminatorKind::FalseEdge { .. } | + TerminatorKind::FalseUnwind { .. } => { + } + + TerminatorKind::Return => { + // `return` logically moves from the return place `_0`. Note that the place + // cannot be changed by any visitor, though. + let $($mutability)? local = RETURN_PLACE; + self.visit_local( + & $($mutability)? local, + PlaceContext::NonMutatingUse(NonMutatingUseContext::Move), + location, + ); + + assert_eq!( + local, + RETURN_PLACE, + "`MutVisitor` tried to mutate return place of `return` terminator" + ); + } + + TerminatorKind::SwitchInt { + discr, + switch_ty, + values: _, + targets: _ + } => { + self.visit_operand(discr, location); + self.visit_ty(switch_ty, TyContext::Location(location)); + } + + TerminatorKind::Drop { + place, + target: _, + unwind: _, + } => { + self.visit_place( + place, + PlaceContext::MutatingUse(MutatingUseContext::Drop), + location + ); + } + + TerminatorKind::DropAndReplace { + place, + value, + target: _, + unwind: _, + } => { + self.visit_place( + place, + PlaceContext::MutatingUse(MutatingUseContext::Drop), + location + ); + self.visit_operand(value, location); + } + + TerminatorKind::Call { + func, + args, + destination, + cleanup: _, + from_hir_call: _, + fn_span: _ + } => { + self.visit_operand(func, location); + for arg in args { + self.visit_operand(arg, location); + } + if let Some((destination, _)) = destination { + self.visit_place( + destination, + PlaceContext::MutatingUse(MutatingUseContext::Call), + location + ); + } + } + + TerminatorKind::Assert { + cond, + expected: _, + msg, + target: _, + cleanup: _, + } => { + self.visit_operand(cond, location); + self.visit_assert_message(msg, location); + } + + TerminatorKind::Yield { + value, + resume: _, + resume_arg, + drop: _, + } => { + self.visit_operand(value, location); + self.visit_place( + resume_arg, + PlaceContext::MutatingUse(MutatingUseContext::Yield), + location, + ); + } + + TerminatorKind::InlineAsm { + template: _, + operands, + options: _, + line_spans: _, + destination: _, + } => { + for op in operands { + match op { + InlineAsmOperand::In { value, .. } + | InlineAsmOperand::Const { value } => { + self.visit_operand(value, location); + } + InlineAsmOperand::Out { place, .. } => { + if let Some(place) = place { + self.visit_place( + place, + PlaceContext::MutatingUse(MutatingUseContext::Store), + location, + ); + } + } + InlineAsmOperand::InOut { in_value, out_place, .. } => { + self.visit_operand(in_value, location); + if let Some(out_place) = out_place { + self.visit_place( + out_place, + PlaceContext::MutatingUse(MutatingUseContext::Store), + location, + ); + } + } + InlineAsmOperand::SymFn { value } => { + self.visit_constant(value, location); + } + InlineAsmOperand::SymStatic { def_id: _ } => {} + } + } + } + } + } + + fn super_assert_message(&mut self, + msg: & $($mutability)? AssertMessage<'tcx>, + location: Location) { + use crate::mir::AssertKind::*; + match msg { + BoundsCheck { len, index } => { + self.visit_operand(len, location); + self.visit_operand(index, location); + } + Overflow(_, l, r) => { + self.visit_operand(l, location); + self.visit_operand(r, location); + } + OverflowNeg(op) | DivisionByZero(op) | RemainderByZero(op) => { + self.visit_operand(op, location); + } + ResumedAfterReturn(_) | ResumedAfterPanic(_) => { + // Nothing to visit + } + } + } + + fn super_rvalue(&mut self, + rvalue: & $($mutability)? Rvalue<'tcx>, + location: Location) { + match rvalue { + Rvalue::Use(operand) => { + self.visit_operand(operand, location); + } + + Rvalue::Repeat(value, _) => { + self.visit_operand(value, location); + } + + Rvalue::ThreadLocalRef(_) => {} + + Rvalue::Ref(r, bk, path) => { + self.visit_region(r, location); + let ctx = match bk { + BorrowKind::Shared => PlaceContext::NonMutatingUse( + NonMutatingUseContext::SharedBorrow + ), + BorrowKind::Shallow => PlaceContext::NonMutatingUse( + NonMutatingUseContext::ShallowBorrow + ), + BorrowKind::Unique => PlaceContext::NonMutatingUse( + NonMutatingUseContext::UniqueBorrow + ), + BorrowKind::Mut { .. } => + PlaceContext::MutatingUse(MutatingUseContext::Borrow), + }; + self.visit_place(path, ctx, location); + } + + Rvalue::AddressOf(m, path) => { + let ctx = match m { + Mutability::Mut => PlaceContext::MutatingUse( + MutatingUseContext::AddressOf + ), + Mutability::Not => PlaceContext::NonMutatingUse( + NonMutatingUseContext::AddressOf + ), + }; + self.visit_place(path, ctx, location); + } + + Rvalue::Len(path) => { + self.visit_place( + path, + PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect), + location + ); + } + + Rvalue::Cast(_cast_kind, operand, ty) => { + self.visit_operand(operand, location); + self.visit_ty(ty, TyContext::Location(location)); + } + + Rvalue::BinaryOp(_bin_op, lhs, rhs) + | Rvalue::CheckedBinaryOp(_bin_op, lhs, rhs) => { + self.visit_operand(lhs, location); + self.visit_operand(rhs, location); + } + + Rvalue::UnaryOp(_un_op, op) => { + self.visit_operand(op, location); + } + + Rvalue::Discriminant(place) => { + self.visit_place( + place, + PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect), + location + ); + } + + Rvalue::NullaryOp(_op, ty) => { + self.visit_ty(ty, TyContext::Location(location)); + } + + Rvalue::Aggregate(kind, operands) => { + let kind = &$($mutability)? **kind; + match kind { + AggregateKind::Array(ty) => { + self.visit_ty(ty, TyContext::Location(location)); + } + AggregateKind::Tuple => { + } + AggregateKind::Adt( + _adt_def, + _variant_index, + substs, + _user_substs, + _active_field_index + ) => { + self.visit_substs(substs, location); + } + AggregateKind::Closure( + _, + closure_substs + ) => { + self.visit_substs(closure_substs, location); + } + AggregateKind::Generator( + _, + generator_substs, + _movability, + ) => { + self.visit_substs(generator_substs, location); + } + } + + for operand in operands { + self.visit_operand(operand, location); + } + } + } + } + + fn super_operand(&mut self, + operand: & $($mutability)? Operand<'tcx>, + location: Location) { + match operand { + Operand::Copy(place) => { + self.visit_place( + place, + PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy), + location + ); + } + Operand::Move(place) => { + self.visit_place( + place, + PlaceContext::NonMutatingUse(NonMutatingUseContext::Move), + location + ); + } + Operand::Constant(constant) => { + self.visit_constant(constant, location); + } + } + } + + fn super_ascribe_user_ty(&mut self, + place: & $($mutability)? Place<'tcx>, + _variance: & $($mutability)? ty::Variance, + user_ty: & $($mutability)? UserTypeProjection, + location: Location) { + self.visit_place( + place, + PlaceContext::NonUse(NonUseContext::AscribeUserTy), + location + ); + self.visit_user_type_projection(user_ty); + } + + fn super_coverage(&mut self, + _kind: & $($mutability)? Coverage, + _location: Location) { + } + + fn super_retag(&mut self, + _kind: & $($mutability)? RetagKind, + place: & $($mutability)? Place<'tcx>, + location: Location) { + self.visit_place( + place, + PlaceContext::MutatingUse(MutatingUseContext::Retag), + location, + ); + } + + fn super_local_decl(&mut self, + local: Local, + local_decl: & $($mutability)? LocalDecl<'tcx>) { + let LocalDecl { + mutability: _, + ty, + user_ty, + source_info, + internal: _, + local_info: _, + is_block_tail: _, + } = local_decl; + + self.visit_ty(ty, TyContext::LocalDecl { + local, + source_info: *source_info, + }); + if let Some(user_ty) = user_ty { + for (user_ty, _) in & $($mutability)? user_ty.contents { + self.visit_user_type_projection(user_ty); + } + } + self.visit_source_info(source_info); + } + + fn super_var_debug_info(&mut self, + var_debug_info: & $($mutability)? VarDebugInfo<'tcx>) { + let VarDebugInfo { + name: _, + source_info, + place, + } = var_debug_info; + + self.visit_source_info(source_info); + let location = START_BLOCK.start_location(); + self.visit_place( + place, + PlaceContext::NonUse(NonUseContext::VarDebugInfo), + location, + ); + } + + fn super_source_scope(&mut self, + _scope: & $($mutability)? SourceScope) { + } + + fn super_constant(&mut self, + constant: & $($mutability)? Constant<'tcx>, + location: Location) { + let Constant { + span, + user_ty, + literal, + } = constant; + + self.visit_span(span); + drop(user_ty); // no visit method for this + self.visit_const(literal, location); + } + + fn super_span(&mut self, _span: & $($mutability)? Span) { + } + + fn super_source_info(&mut self, source_info: & $($mutability)? SourceInfo) { + let SourceInfo { + span, + scope, + } = source_info; + + self.visit_span(span); + self.visit_source_scope(scope); + } + + fn super_user_type_projection( + &mut self, + _ty: & $($mutability)? UserTypeProjection, + ) { + } + + fn super_user_type_annotation( + &mut self, + _index: UserTypeAnnotationIndex, + ty: & $($mutability)? CanonicalUserTypeAnnotation<'tcx>, + ) { + self.visit_span(& $($mutability)? ty.span); + self.visit_ty(& $($mutability)? ty.inferred_ty, TyContext::UserTy(ty.span)); + } + + fn super_ty(&mut self, _ty: $(& $mutability)? Ty<'tcx>) { + } + + fn super_region(&mut self, _region: & $($mutability)? ty::Region<'tcx>) { + } + + fn super_const(&mut self, _const: & $($mutability)? &'tcx ty::Const<'tcx>) { + } + + fn super_substs(&mut self, _substs: & $($mutability)? SubstsRef<'tcx>) { + } + + // Convenience methods + + fn visit_location( + &mut self, + body: &$($mutability)? Body<'tcx>, + location: Location + ) { + macro_rules! basic_blocks { + (mut) => (body.basic_blocks_mut()); + () => (body.basic_blocks()); + }; + let basic_block = & $($mutability)? basic_blocks!($($mutability)?)[location.block]; + if basic_block.statements.len() == location.statement_index { + if let Some(ref $($mutability)? terminator) = basic_block.terminator { + self.visit_terminator(terminator, location) + } + } else { + let statement = & $($mutability)? + basic_block.statements[location.statement_index]; + self.visit_statement(statement, location) + } + } + } + } +} + +macro_rules! visit_place_fns { + (mut) => { + fn tcx<'a>(&'a self) -> TyCtxt<'tcx>; + + fn super_place( + &mut self, + place: &mut Place<'tcx>, + context: PlaceContext, + location: Location, + ) { + self.visit_local(&mut place.local, context, location); + + if let Some(new_projection) = self.process_projection(&place.projection, location) { + place.projection = self.tcx().intern_place_elems(&new_projection); + } + } + + fn process_projection( + &mut self, + projection: &'a [PlaceElem<'tcx>], + location: Location, + ) -> Option<Vec<PlaceElem<'tcx>>> { + let mut projection = Cow::Borrowed(projection); + + for i in 0..projection.len() { + if let Some(&elem) = projection.get(i) { + if let Some(elem) = self.process_projection_elem(elem, location) { + // This converts the borrowed projection into `Cow::Owned(_)` and returns a + // clone of the projection so we can mutate and reintern later. + let vec = projection.to_mut(); + vec[i] = elem; + } + } + } + + match projection { + Cow::Borrowed(_) => None, + Cow::Owned(vec) => Some(vec), + } + } + + fn process_projection_elem( + &mut self, + elem: PlaceElem<'tcx>, + location: Location, + ) -> Option<PlaceElem<'tcx>> { + match elem { + PlaceElem::Index(local) => { + let mut new_local = local; + self.visit_local( + &mut new_local, + PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy), + location, + ); + + if new_local == local { None } else { Some(PlaceElem::Index(new_local)) } + } + PlaceElem::Deref + | PlaceElem::Field(..) + | PlaceElem::ConstantIndex { .. } + | PlaceElem::Subslice { .. } + | PlaceElem::Downcast(..) => None, + } + } + }; + + () => { + fn visit_projection( + &mut self, + local: Local, + projection: &[PlaceElem<'tcx>], + context: PlaceContext, + location: Location, + ) { + self.super_projection(local, projection, context, location); + } + + fn visit_projection_elem( + &mut self, + local: Local, + proj_base: &[PlaceElem<'tcx>], + elem: PlaceElem<'tcx>, + context: PlaceContext, + location: Location, + ) { + self.super_projection_elem(local, proj_base, elem, context, location); + } + + fn super_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) { + let mut context = context; + + if !place.projection.is_empty() { + context = if context.is_mutating_use() { + PlaceContext::MutatingUse(MutatingUseContext::Projection) + } else { + PlaceContext::NonMutatingUse(NonMutatingUseContext::Projection) + }; + } + + self.visit_local(&place.local, context, location); + + self.visit_projection(place.local, &place.projection, context, location); + } + + fn super_projection( + &mut self, + local: Local, + projection: &[PlaceElem<'tcx>], + context: PlaceContext, + location: Location, + ) { + let mut cursor = projection; + while let &[ref proj_base @ .., elem] = cursor { + cursor = proj_base; + self.visit_projection_elem(local, cursor, elem, context, location); + } + } + + fn super_projection_elem( + &mut self, + _local: Local, + _proj_base: &[PlaceElem<'tcx>], + elem: PlaceElem<'tcx>, + _context: PlaceContext, + location: Location, + ) { + match elem { + ProjectionElem::Field(_field, ty) => { + self.visit_ty(ty, TyContext::Location(location)); + } + ProjectionElem::Index(local) => { + self.visit_local( + &local, + PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy), + location, + ); + } + ProjectionElem::Deref + | ProjectionElem::Subslice { from: _, to: _, from_end: _ } + | ProjectionElem::ConstantIndex { offset: _, min_length: _, from_end: _ } + | ProjectionElem::Downcast(_, _) => {} + } + } + }; +} + +make_mir_visitor!(Visitor,); +make_mir_visitor!(MutVisitor, mut); + +pub trait MirVisitable<'tcx> { + fn apply(&self, location: Location, visitor: &mut dyn Visitor<'tcx>); +} + +impl<'tcx> MirVisitable<'tcx> for Statement<'tcx> { + fn apply(&self, location: Location, visitor: &mut dyn Visitor<'tcx>) { + visitor.visit_statement(self, location) + } +} + +impl<'tcx> MirVisitable<'tcx> for Terminator<'tcx> { + fn apply(&self, location: Location, visitor: &mut dyn Visitor<'tcx>) { + visitor.visit_terminator(self, location) + } +} + +impl<'tcx> MirVisitable<'tcx> for Option<Terminator<'tcx>> { + fn apply(&self, location: Location, visitor: &mut dyn Visitor<'tcx>) { + visitor.visit_terminator(self.as_ref().unwrap(), location) + } +} + +/// Extra information passed to `visit_ty` and friends to give context +/// about where the type etc appears. +#[derive(Debug)] +pub enum TyContext { + LocalDecl { + /// The index of the local variable we are visiting. + local: Local, + + /// The source location where this local variable was declared. + source_info: SourceInfo, + }, + + /// The inferred type of a user type annotation. + UserTy(Span), + + /// The return type of the function. + ReturnTy(SourceInfo), + + YieldTy(SourceInfo), + + /// A type found at some location. + Location(Location), +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum NonMutatingUseContext { + /// Being inspected in some way, like loading a len. + Inspect, + /// Consumed as part of an operand. + Copy, + /// Consumed as part of an operand. + Move, + /// Shared borrow. + SharedBorrow, + /// Shallow borrow. + ShallowBorrow, + /// Unique borrow. + UniqueBorrow, + /// AddressOf for *const pointer. + AddressOf, + /// Used as base for another place, e.g., `x` in `x.y`. Will not mutate the place. + /// For example, the projection `x.y` is not marked as a mutation in these cases: + /// + /// z = x.y; + /// f(&x.y); + /// + Projection, +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum MutatingUseContext { + /// Appears as LHS of an assignment. + Store, + /// Can often be treated as a `Store`, but needs to be separate because + /// ASM is allowed to read outputs as well, so a `Store`-`AsmOutput` sequence + /// cannot be simplified the way a `Store`-`Store` can be. + AsmOutput, + /// Destination of a call. + Call, + /// Destination of a yield. + Yield, + /// Being dropped. + Drop, + /// Mutable borrow. + Borrow, + /// AddressOf for *mut pointer. + AddressOf, + /// Used as base for another place, e.g., `x` in `x.y`. Could potentially mutate the place. + /// For example, the projection `x.y` is marked as a mutation in these cases: + /// + /// x.y = ...; + /// f(&mut x.y); + /// + Projection, + /// Retagging, a "Stacked Borrows" shadow state operation + Retag, +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum NonUseContext { + /// Starting a storage live range. + StorageLive, + /// Ending a storage live range. + StorageDead, + /// User type annotation assertions for NLL. + AscribeUserTy, + /// Coverage code region and counter metadata. + Coverage, + /// The data of an user variable, for debug info. + VarDebugInfo, +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum PlaceContext { + NonMutatingUse(NonMutatingUseContext), + MutatingUse(MutatingUseContext), + NonUse(NonUseContext), +} + +impl PlaceContext { + /// Returns `true` if this place context represents a drop. + pub fn is_drop(&self) -> bool { + match *self { + PlaceContext::MutatingUse(MutatingUseContext::Drop) => true, + _ => false, + } + } + + /// Returns `true` if this place context represents a borrow. + pub fn is_borrow(&self) -> bool { + match *self { + PlaceContext::NonMutatingUse( + NonMutatingUseContext::SharedBorrow + | NonMutatingUseContext::ShallowBorrow + | NonMutatingUseContext::UniqueBorrow, + ) + | PlaceContext::MutatingUse(MutatingUseContext::Borrow) => true, + _ => false, + } + } + + /// Returns `true` if this place context represents a storage live or storage dead marker. + pub fn is_storage_marker(&self) -> bool { + match *self { + PlaceContext::NonUse(NonUseContext::StorageLive | NonUseContext::StorageDead) => true, + _ => false, + } + } + + /// Returns `true` if this place context represents a storage live marker. + pub fn is_storage_live_marker(&self) -> bool { + match *self { + PlaceContext::NonUse(NonUseContext::StorageLive) => true, + _ => false, + } + } + + /// Returns `true` if this place context represents a storage dead marker. + pub fn is_storage_dead_marker(&self) -> bool { + match *self { + PlaceContext::NonUse(NonUseContext::StorageDead) => true, + _ => false, + } + } + + /// Returns `true` if this place context represents a use that potentially changes the value. + pub fn is_mutating_use(&self) -> bool { + match *self { + PlaceContext::MutatingUse(..) => true, + _ => false, + } + } + + /// Returns `true` if this place context represents a use that does not change the value. + pub fn is_nonmutating_use(&self) -> bool { + match *self { + PlaceContext::NonMutatingUse(..) => true, + _ => false, + } + } + + /// Returns `true` if this place context represents a use. + pub fn is_use(&self) -> bool { + match *self { + PlaceContext::NonUse(..) => false, + _ => true, + } + } + + /// Returns `true` if this place context represents an assignment statement. + pub fn is_place_assignment(&self) -> bool { + match *self { + PlaceContext::MutatingUse( + MutatingUseContext::Store + | MutatingUseContext::Call + | MutatingUseContext::AsmOutput, + ) => true, + _ => false, + } + } +} diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs new file mode 100644 index 00000000000..e05752f08f6 --- /dev/null +++ b/compiler/rustc_middle/src/query/mod.rs @@ -0,0 +1,1551 @@ +use crate::dep_graph::SerializedDepNodeIndex; +use crate::mir::interpret::{GlobalId, LitToConstInput}; +use crate::traits; +use crate::traits::query::{ + CanonicalPredicateGoal, CanonicalProjectionGoal, CanonicalTyGoal, + CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal, + CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpSubtypeGoal, +}; +use crate::ty::query::queries; +use crate::ty::subst::{GenericArg, SubstsRef}; +use crate::ty::{self, ParamEnvAnd, Ty, TyCtxt}; +use rustc_hir::def_id::{CrateNum, DefId, LocalDefId}; +use rustc_query_system::query::QueryDescription; + +use rustc_span::symbol::Symbol; +use std::borrow::Cow; + +fn describe_as_module(def_id: LocalDefId, tcx: TyCtxt<'_>) -> String { + if def_id.is_top_level_module() { + "top-level module".to_string() + } else { + format!("module `{}`", tcx.def_path_str(def_id.to_def_id())) + } +} + +// Each of these queries corresponds to a function pointer field in the +// `Providers` struct for requesting a value of that type, and a method +// on `tcx: TyCtxt` (and `tcx.at(span)`) for doing that request in a way +// which memoizes and does dep-graph tracking, wrapping around the actual +// `Providers` that the driver creates (using several `rustc_*` crates). +// +// The result type of each query must implement `Clone`, and additionally +// `ty::query::values::Value`, which produces an appropriate placeholder +// (error) value if the query resulted in a query cycle. +// Queries marked with `fatal_cycle` do not need the latter implementation, +// as they will raise an fatal error on query cycles instead. +rustc_queries! { + Other { + query trigger_delay_span_bug(key: DefId) -> () { + desc { "trigger a delay span bug" } + } + } + + Other { + // Represents crate as a whole (as distinct from the top-level crate module). + // If you call `hir_crate` (e.g., indirectly by calling `tcx.hir().krate()`), + // we will have to assume that any change means that you need to be recompiled. + // This is because the `hir_crate` query gives you access to all other items. + // To avoid this fate, do not call `tcx.hir().krate()`; instead, + // prefer wrappers like `tcx.visit_all_items_in_krate()`. + query hir_crate(key: CrateNum) -> &'tcx Crate<'tcx> { + eval_always + no_hash + desc { "get the crate HIR" } + } + + // The indexed HIR. This can be conveniently accessed by `tcx.hir()`. + // Avoid calling this query directly. + query index_hir(_: CrateNum) -> &'tcx map::IndexedHir<'tcx> { + eval_always + no_hash + desc { "index HIR" } + } + + // The items in a module. + // + // This can be conveniently accessed by `tcx.hir().visit_item_likes_in_module`. + // Avoid calling this query directly. + query hir_module_items(key: LocalDefId) -> &'tcx hir::ModuleItems { + eval_always + desc { |tcx| "HIR module items in `{}`", tcx.def_path_str(key.to_def_id()) } + } + + // Gives access to the HIR node for the HIR owner `key`. + // + // This can be conveniently accessed by methods on `tcx.hir()`. + // Avoid calling this query directly. + query hir_owner(key: LocalDefId) -> Option<&'tcx crate::hir::Owner<'tcx>> { + eval_always + desc { |tcx| "HIR owner of `{}`", tcx.def_path_str(key.to_def_id()) } + } + + // Gives access to the HIR nodes and bodies inside the HIR owner `key`. + // + // This can be conveniently accessed by methods on `tcx.hir()`. + // Avoid calling this query directly. + query hir_owner_nodes(key: LocalDefId) -> Option<&'tcx crate::hir::OwnerNodes<'tcx>> { + eval_always + desc { |tcx| "HIR owner items in `{}`", tcx.def_path_str(key.to_def_id()) } + } + + /// Computes the `DefId` of the corresponding const parameter in case the `key` is a + /// const argument and returns `None` otherwise. + /// + /// ```rust + /// let a = foo::<7>(); + /// // ^ Calling `opt_const_param_of` for this argument, + /// + /// fn foo<const N: usize>() + /// // ^ returns this `DefId`. + /// + /// fn bar() { + /// // ^ While calling `opt_const_param_of` for other bodies returns `None`. + /// } + /// ``` + // It looks like caching this query on disk actually slightly + // worsened performance in #74376. + // + // Once const generics are more prevalently used, we might want to + // consider only caching calls returning `Some`. + query opt_const_param_of(key: LocalDefId) -> Option<DefId> { + desc { |tcx| "computing the optional const parameter of `{}`", tcx.def_path_str(key.to_def_id()) } + } + + /// Records the type of every item. + query type_of(key: DefId) -> Ty<'tcx> { + desc { |tcx| "computing type of `{}`", tcx.def_path_str(key) } + cache_on_disk_if { key.is_local() } + } + + query analysis(key: CrateNum) -> Result<(), ErrorReported> { + eval_always + desc { "running analysis passes on this crate" } + } + + /// Maps from the `DefId` of an item (trait/struct/enum/fn) to its + /// associated generics. + query generics_of(key: DefId) -> ty::Generics { + desc { |tcx| "computing generics of `{}`", tcx.def_path_str(key) } + storage(ArenaCacheSelector<'tcx>) + cache_on_disk_if { key.is_local() } + load_cached(tcx, id) { + let generics: Option<ty::Generics> = tcx.queries.on_disk_cache + .try_load_query_result(tcx, id); + generics + } + } + + /// Maps from the `DefId` of an item (trait/struct/enum/fn) to the + /// predicates (where-clauses) that must be proven true in order + /// to reference it. This is almost always the "predicates query" + /// that you want. + /// + /// `predicates_of` builds on `predicates_defined_on` -- in fact, + /// it is almost always the same as that query, except for the + /// case of traits. For traits, `predicates_of` contains + /// an additional `Self: Trait<...>` predicate that users don't + /// actually write. This reflects the fact that to invoke the + /// trait (e.g., via `Default::default`) you must supply types + /// that actually implement the trait. (However, this extra + /// predicate gets in the way of some checks, which are intended + /// to operate over only the actual where-clauses written by the + /// user.) + query predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> { + desc { |tcx| "computing predicates of `{}`", tcx.def_path_str(key) } + cache_on_disk_if { key.is_local() } + } + + /// Returns the list of predicates that can be used for + /// `SelectionCandidate::ProjectionCandidate` and + /// `ProjectionTyCandidate::TraitDef`. + /// Specifically this is the bounds (equivalent to) those + /// written on the trait's type definition, or those + /// after the `impl` keyword + /// + /// type X: Bound + 'lt + /// ^^^^^^^^^^^ + /// impl Debug + Display + /// ^^^^^^^^^^^^^^^ + /// + /// `key` is the `DefId` of the associated type or opaque type. + query projection_predicates(key: DefId) -> &'tcx ty::List<ty::Predicate<'tcx>> { + desc { |tcx| "finding projection predicates for `{}`", tcx.def_path_str(key) } + } + + query projection_ty_from_predicates(key: (DefId, DefId)) -> Option<ty::ProjectionTy<'tcx>> { + desc { |tcx| "finding projection type inside predicates of `{}`", tcx.def_path_str(key.0) } + } + + query native_libraries(_: CrateNum) -> Lrc<Vec<NativeLib>> { + desc { "looking up the native libraries of a linked crate" } + } + + query lint_levels(_: CrateNum) -> LintLevelMap { + storage(ArenaCacheSelector<'tcx>) + eval_always + desc { "computing the lint levels for items in this crate" } + } + + query parent_module_from_def_id(key: LocalDefId) -> LocalDefId { + eval_always + desc { |tcx| "parent module of `{}`", tcx.def_path_str(key.to_def_id()) } + } + } + + Codegen { + query is_panic_runtime(_: CrateNum) -> bool { + fatal_cycle + desc { "checking if the crate is_panic_runtime" } + } + } + + Codegen { + /// Set of all the `DefId`s in this crate that have MIR associated with + /// them. This includes all the body owners, but also things like struct + /// constructors. + query mir_keys(_: CrateNum) -> FxHashSet<LocalDefId> { + storage(ArenaCacheSelector<'tcx>) + desc { "getting a list of all mir_keys" } + } + + /// Maps DefId's that have an associated `mir::Body` to the result + /// of the MIR const-checking pass. This is the set of qualifs in + /// the final value of a `const`. + query mir_const_qualif(key: DefId) -> mir::ConstQualifs { + desc { |tcx| "const checking `{}`", tcx.def_path_str(key) } + cache_on_disk_if { key.is_local() } + } + query mir_const_qualif_const_arg( + key: (LocalDefId, DefId) + ) -> mir::ConstQualifs { + desc { + |tcx| "const checking the const argument `{}`", + tcx.def_path_str(key.0.to_def_id()) + } + } + + /// Fetch the MIR for a given `DefId` right after it's built - this includes + /// unreachable code. + query mir_built(key: ty::WithOptConstParam<LocalDefId>) -> &'tcx Steal<mir::Body<'tcx>> { + desc { |tcx| "building MIR for `{}`", tcx.def_path_str(key.did.to_def_id()) } + } + + /// Fetch the MIR for a given `DefId` up till the point where it is + /// ready for const qualification. + /// + /// See the README for the `mir` module for details. + query mir_const(key: ty::WithOptConstParam<LocalDefId>) -> &'tcx Steal<mir::Body<'tcx>> { + desc { + |tcx| "processing MIR for {}`{}`", + if key.const_param_did.is_some() { "the const argument " } else { "" }, + tcx.def_path_str(key.did.to_def_id()), + } + no_hash + } + + query mir_drops_elaborated_and_const_checked( + key: ty::WithOptConstParam<LocalDefId> + ) -> &'tcx Steal<mir::Body<'tcx>> { + no_hash + desc { |tcx| "elaborating drops for `{}`", tcx.def_path_str(key.did.to_def_id()) } + } + + query mir_promoted(key: ty::WithOptConstParam<LocalDefId>) -> + ( + &'tcx Steal<mir::Body<'tcx>>, + &'tcx Steal<IndexVec<mir::Promoted, mir::Body<'tcx>>> + ) { + no_hash + desc { + |tcx| "processing {}`{}`", + if key.const_param_did.is_some() { "the const argument " } else { "" }, + tcx.def_path_str(key.did.to_def_id()), + } + } + + /// MIR after our optimization passes have run. This is MIR that is ready + /// for codegen. This is also the only query that can fetch non-local MIR, at present. + query optimized_mir(key: DefId) -> &'tcx mir::Body<'tcx> { + desc { |tcx| "optimizing MIR for `{}`", tcx.def_path_str(key) } + cache_on_disk_if { key.is_local() } + } + query optimized_mir_of_const_arg(key: (LocalDefId, DefId)) -> &'tcx mir::Body<'tcx> { + desc { + |tcx| "optimizing MIR for the const argument `{}`", + tcx.def_path_str(key.0.to_def_id()) + } + } + + /// Returns coverage summary info for a function, after executing the `InstrumentCoverage` + /// MIR pass (assuming the -Zinstrument-coverage option is enabled). + query coverageinfo(key: DefId) -> mir::CoverageInfo { + desc { |tcx| "retrieving coverage info from MIR for `{}`", tcx.def_path_str(key) } + storage(ArenaCacheSelector<'tcx>) + cache_on_disk_if { key.is_local() } + } + + /// The `DefId` is the `DefId` of the containing MIR body. Promoteds do not have their own + /// `DefId`. This function returns all promoteds in the specified body. The body references + /// promoteds by the `DefId` and the `mir::Promoted` index. This is necessary, because + /// after inlining a body may refer to promoteds from other bodies. In that case you still + /// need to use the `DefId` of the original body. + query promoted_mir(key: DefId) -> &'tcx IndexVec<mir::Promoted, mir::Body<'tcx>> { + desc { |tcx| "optimizing promoted MIR for `{}`", tcx.def_path_str(key) } + cache_on_disk_if { key.is_local() } + } + query promoted_mir_of_const_arg( + key: (LocalDefId, DefId) + ) -> &'tcx IndexVec<mir::Promoted, mir::Body<'tcx>> { + desc { + |tcx| "optimizing promoted MIR for the const argument `{}`", + tcx.def_path_str(key.0.to_def_id()), + } + } + } + + TypeChecking { + // Erases regions from `ty` to yield a new type. + // Normally you would just use `tcx.erase_regions(&value)`, + // however, which uses this query as a kind of cache. + query erase_regions_ty(ty: Ty<'tcx>) -> Ty<'tcx> { + // This query is not expected to have input -- as a result, it + // is not a good candidates for "replay" because it is essentially a + // pure function of its input (and hence the expectation is that + // no caller would be green **apart** from just these + // queries). Making it anonymous avoids hashing the result, which + // may save a bit of time. + anon + desc { "erasing regions from `{:?}`", ty } + } + } + + Linking { + query wasm_import_module_map(_: CrateNum) -> FxHashMap<DefId, String> { + storage(ArenaCacheSelector<'tcx>) + desc { "wasm import module map" } + } + } + + Other { + /// Maps from the `DefId` of an item (trait/struct/enum/fn) to the + /// predicates (where-clauses) directly defined on it. This is + /// equal to the `explicit_predicates_of` predicates plus the + /// `inferred_outlives_of` predicates. + query predicates_defined_on(key: DefId) -> ty::GenericPredicates<'tcx> { + desc { |tcx| "computing predicates of `{}`", tcx.def_path_str(key) } + } + + /// Returns the predicates written explicitly by the user. + query explicit_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> { + desc { |tcx| "computing explicit predicates of `{}`", tcx.def_path_str(key) } + } + + /// Returns the inferred outlives predicates (e.g., for `struct + /// Foo<'a, T> { x: &'a T }`, this would return `T: 'a`). + query inferred_outlives_of(key: DefId) -> &'tcx [(ty::Predicate<'tcx>, Span)] { + desc { |tcx| "computing inferred outlives predicates of `{}`", tcx.def_path_str(key) } + } + + /// Maps from the `DefId` of a trait to the list of + /// super-predicates. This is a subset of the full list of + /// predicates. We store these in a separate map because we must + /// evaluate them even during type conversion, often before the + /// full predicates are available (note that supertraits have + /// additional acyclicity requirements). + query super_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> { + desc { |tcx| "computing the supertraits of `{}`", tcx.def_path_str(key) } + } + + /// To avoid cycles within the predicates of a single item we compute + /// per-type-parameter predicates for resolving `T::AssocTy`. + query type_param_predicates(key: (DefId, LocalDefId)) -> ty::GenericPredicates<'tcx> { + desc { |tcx| "computing the bounds for type parameter `{}`", { + let id = tcx.hir().local_def_id_to_hir_id(key.1); + tcx.hir().ty_param_name(id) + }} + } + + query trait_def(key: DefId) -> ty::TraitDef { + desc { |tcx| "computing trait definition for `{}`", tcx.def_path_str(key) } + storage(ArenaCacheSelector<'tcx>) + } + query adt_def(key: DefId) -> &'tcx ty::AdtDef { + desc { |tcx| "computing ADT definition for `{}`", tcx.def_path_str(key) } + } + query adt_destructor(key: DefId) -> Option<ty::Destructor> { + desc { |tcx| "computing `Drop` impl for `{}`", tcx.def_path_str(key) } + } + + // The cycle error here should be reported as an error by `check_representable`. + // We consider the type as Sized in the meanwhile to avoid + // further errors (done in impl Value for AdtSizedConstraint). + // Use `cycle_delay_bug` to delay the cycle error here to be emitted later + // in case we accidentally otherwise don't emit an error. + query adt_sized_constraint( + key: DefId + ) -> AdtSizedConstraint<'tcx> { + desc { |tcx| "computing `Sized` constraints for `{}`", tcx.def_path_str(key) } + cycle_delay_bug + } + + query adt_dtorck_constraint( + key: DefId + ) -> Result<DtorckConstraint<'tcx>, NoSolution> { + desc { |tcx| "computing drop-check constraints for `{}`", tcx.def_path_str(key) } + } + + /// Returns `true` if this is a const fn, use the `is_const_fn` to know whether your crate + /// actually sees it as const fn (e.g., the const-fn-ness might be unstable and you might + /// not have the feature gate active). + /// + /// **Do not call this function manually.** It is only meant to cache the base data for the + /// `is_const_fn` function. + query is_const_fn_raw(key: DefId) -> bool { + desc { |tcx| "checking if item is const fn: `{}`", tcx.def_path_str(key) } + } + + /// Returns `true` if this is a const `impl`. **Do not call this function manually.** + /// + /// This query caches the base data for the `is_const_impl` helper function, which also + /// takes into account stability attributes (e.g., `#[rustc_const_unstable]`). + query is_const_impl_raw(key: DefId) -> bool { + desc { |tcx| "checking if item is const impl: `{}`", tcx.def_path_str(key) } + } + + query asyncness(key: DefId) -> hir::IsAsync { + desc { |tcx| "checking if the function is async: `{}`", tcx.def_path_str(key) } + } + + /// Returns `true` if calls to the function may be promoted. + /// + /// This is either because the function is e.g., a tuple-struct or tuple-variant + /// constructor, or because it has the `#[rustc_promotable]` attribute. The attribute should + /// be removed in the future in favour of some form of check which figures out whether the + /// function does not inspect the bits of any of its arguments (so is essentially just a + /// constructor function). + query is_promotable_const_fn(key: DefId) -> bool { + desc { |tcx| "checking if item is promotable: `{}`", tcx.def_path_str(key) } + } + + query const_fn_is_allowed_fn_ptr(key: DefId) -> bool { + desc { |tcx| "checking if const fn allows `fn()` types: `{}`", tcx.def_path_str(key) } + } + + /// Returns `true` if this is a foreign item (i.e., linked via `extern { ... }`). + query is_foreign_item(key: DefId) -> bool { + desc { |tcx| "checking if `{}` is a foreign item", tcx.def_path_str(key) } + } + + /// Returns `Some(mutability)` if the node pointed to by `def_id` is a static item. + query static_mutability(def_id: DefId) -> Option<hir::Mutability> { + desc { |tcx| "looking up static mutability of `{}`", tcx.def_path_str(def_id) } + } + + /// Returns `Some(generator_kind)` if the node pointed to by `def_id` is a generator. + query generator_kind(def_id: DefId) -> Option<hir::GeneratorKind> { + desc { |tcx| "looking up generator kind of `{}`", tcx.def_path_str(def_id) } + } + + /// Gets a map with the variance of every item; use `item_variance` instead. + query crate_variances(_: CrateNum) -> ty::CrateVariancesMap<'tcx> { + storage(ArenaCacheSelector<'tcx>) + desc { "computing the variances for items in this crate" } + } + + /// Maps from the `DefId` of a type or region parameter to its (inferred) variance. + query variances_of(def_id: DefId) -> &'tcx [ty::Variance] { + desc { |tcx| "computing the variances of `{}`", tcx.def_path_str(def_id) } + } + } + + TypeChecking { + /// Maps from thee `DefId` of a type to its (inferred) outlives. + query inferred_outlives_crate(_: CrateNum) + -> ty::CratePredicatesMap<'tcx> { + storage(ArenaCacheSelector<'tcx>) + desc { "computing the inferred outlives predicates for items in this crate" } + } + } + + Other { + /// Maps from an impl/trait `DefId to a list of the `DefId`s of its items. + query associated_item_def_ids(key: DefId) -> &'tcx [DefId] { + desc { |tcx| "collecting associated items of `{}`", tcx.def_path_str(key) } + } + + /// Maps from a trait item to the trait item "descriptor". + query associated_item(key: DefId) -> ty::AssocItem { + desc { |tcx| "computing associated item data for `{}`", tcx.def_path_str(key) } + storage(ArenaCacheSelector<'tcx>) + } + + /// Collects the associated items defined on a trait or impl. + query associated_items(key: DefId) -> ty::AssociatedItems<'tcx> { + storage(ArenaCacheSelector<'tcx>) + desc { |tcx| "collecting associated items of {}", tcx.def_path_str(key) } + } + + query impl_trait_ref(key: DefId) -> Option<ty::TraitRef<'tcx>> { + desc { |tcx| "computing trait implemented by `{}`", tcx.def_path_str(key) } + } + query impl_polarity(key: DefId) -> ty::ImplPolarity { + desc { |tcx| "computing implementation polarity of `{}`", tcx.def_path_str(key) } + } + + query issue33140_self_ty(key: DefId) -> Option<ty::Ty<'tcx>> { + desc { |tcx| "computing Self type wrt issue #33140 `{}`", tcx.def_path_str(key) } + } + } + + TypeChecking { + /// Maps a `DefId` of a type to a list of its inherent impls. + /// Contains implementations of methods that are inherent to a type. + /// Methods in these implementations don't need to be exported. + query inherent_impls(key: DefId) -> &'tcx [DefId] { + desc { |tcx| "collecting inherent impls for `{}`", tcx.def_path_str(key) } + eval_always + } + } + + TypeChecking { + /// The result of unsafety-checking this `LocalDefId`. + query unsafety_check_result(key: LocalDefId) -> &'tcx mir::UnsafetyCheckResult { + desc { |tcx| "unsafety-checking `{}`", tcx.def_path_str(key.to_def_id()) } + cache_on_disk_if { true } + } + query unsafety_check_result_for_const_arg(key: (LocalDefId, DefId)) -> &'tcx mir::UnsafetyCheckResult { + desc { + |tcx| "unsafety-checking the const argument `{}`", + tcx.def_path_str(key.0.to_def_id()) + } + } + + /// HACK: when evaluated, this reports a "unsafe derive on repr(packed)" error. + /// + /// Unsafety checking is executed for each method separately, but we only want + /// to emit this error once per derive. As there are some impls with multiple + /// methods, we use a query for deduplication. + query unsafe_derive_on_repr_packed(key: LocalDefId) -> () { + desc { |tcx| "processing `{}`", tcx.def_path_str(key.to_def_id()) } + } + + /// The signature of functions. + query fn_sig(key: DefId) -> ty::PolyFnSig<'tcx> { + desc { |tcx| "computing function signature of `{}`", tcx.def_path_str(key) } + } + } + + Other { + query lint_mod(key: LocalDefId) -> () { + desc { |tcx| "linting {}", describe_as_module(key, tcx) } + } + + /// Checks the attributes in the module. + query check_mod_attrs(key: LocalDefId) -> () { + desc { |tcx| "checking attributes in {}", describe_as_module(key, tcx) } + } + + query check_mod_unstable_api_usage(key: LocalDefId) -> () { + desc { |tcx| "checking for unstable API usage in {}", describe_as_module(key, tcx) } + } + + /// Checks the const bodies in the module for illegal operations (e.g. `if` or `loop`). + query check_mod_const_bodies(key: LocalDefId) -> () { + desc { |tcx| "checking consts in {}", describe_as_module(key, tcx) } + } + + /// Checks the loops in the module. + query check_mod_loops(key: LocalDefId) -> () { + desc { |tcx| "checking loops in {}", describe_as_module(key, tcx) } + } + + query check_mod_item_types(key: LocalDefId) -> () { + desc { |tcx| "checking item types in {}", describe_as_module(key, tcx) } + } + + query check_mod_privacy(key: LocalDefId) -> () { + desc { |tcx| "checking privacy in {}", describe_as_module(key, tcx) } + } + + query check_mod_intrinsics(key: LocalDefId) -> () { + desc { |tcx| "checking intrinsics in {}", describe_as_module(key, tcx) } + } + + query check_mod_liveness(key: LocalDefId) -> () { + desc { |tcx| "checking liveness of variables in {}", describe_as_module(key, tcx) } + } + + query check_mod_impl_wf(key: LocalDefId) -> () { + desc { |tcx| "checking that impls are well-formed in {}", describe_as_module(key, tcx) } + } + + query collect_mod_item_types(key: LocalDefId) -> () { + desc { |tcx| "collecting item types in {}", describe_as_module(key, tcx) } + } + + /// Caches `CoerceUnsized` kinds for impls on custom types. + query coerce_unsized_info(key: DefId) + -> ty::adjustment::CoerceUnsizedInfo { + desc { |tcx| "computing CoerceUnsized info for `{}`", tcx.def_path_str(key) } + } + } + + TypeChecking { + query typeck_item_bodies(_: CrateNum) -> () { + desc { "type-checking all item bodies" } + } + + query typeck(key: LocalDefId) -> &'tcx ty::TypeckResults<'tcx> { + desc { |tcx| "type-checking `{}`", tcx.def_path_str(key.to_def_id()) } + cache_on_disk_if { true } + } + query typeck_const_arg( + key: (LocalDefId, DefId) + ) -> &'tcx ty::TypeckResults<'tcx> { + desc { + |tcx| "type-checking the const argument `{}`", + tcx.def_path_str(key.0.to_def_id()), + } + } + query diagnostic_only_typeck(key: LocalDefId) -> &'tcx ty::TypeckResults<'tcx> { + desc { |tcx| "type-checking `{}`", tcx.def_path_str(key.to_def_id()) } + cache_on_disk_if { true } + load_cached(tcx, id) { + let typeck_results: Option<ty::TypeckResults<'tcx>> = tcx + .queries.on_disk_cache + .try_load_query_result(tcx, id); + + typeck_results.map(|x| &*tcx.arena.alloc(x)) + } + } + } + + Other { + query used_trait_imports(key: LocalDefId) -> &'tcx FxHashSet<LocalDefId> { + desc { |tcx| "used_trait_imports `{}`", tcx.def_path_str(key.to_def_id()) } + cache_on_disk_if { true } + } + } + + TypeChecking { + query has_typeck_results(def_id: DefId) -> bool { + desc { |tcx| "checking whether `{}` has a body", tcx.def_path_str(def_id) } + } + + query coherent_trait(def_id: DefId) -> () { + desc { |tcx| "coherence checking all impls of trait `{}`", tcx.def_path_str(def_id) } + } + } + + BorrowChecking { + /// Borrow-checks the function body. If this is a closure, returns + /// additional requirements that the closure's creator must verify. + query mir_borrowck(key: LocalDefId) -> &'tcx mir::BorrowCheckResult<'tcx> { + desc { |tcx| "borrow-checking `{}`", tcx.def_path_str(key.to_def_id()) } + cache_on_disk_if(tcx, opt_result) { + tcx.is_closure(key.to_def_id()) + || opt_result.map_or(false, |r| !r.concrete_opaque_types.is_empty()) + } + } + query mir_borrowck_const_arg(key: (LocalDefId, DefId)) -> &'tcx mir::BorrowCheckResult<'tcx> { + desc { + |tcx| "borrow-checking the const argument`{}`", + tcx.def_path_str(key.0.to_def_id()) + } + } + } + + TypeChecking { + /// Gets a complete map from all types to their inherent impls. + /// Not meant to be used directly outside of coherence. + /// (Defined only for `LOCAL_CRATE`.) + query crate_inherent_impls(k: CrateNum) + -> CrateInherentImpls { + storage(ArenaCacheSelector<'tcx>) + eval_always + desc { "all inherent impls defined in crate `{:?}`", k } + } + + /// Checks all types in the crate for overlap in their inherent impls. Reports errors. + /// Not meant to be used directly outside of coherence. + /// (Defined only for `LOCAL_CRATE`.) + query crate_inherent_impls_overlap_check(_: CrateNum) + -> () { + eval_always + desc { "check for overlap between inherent impls defined in this crate" } + } + } + + Other { + /// Evaluates a constant without running sanity checks. + /// + /// **Do not use this** outside const eval. Const eval uses this to break query cycles + /// during validation. Please add a comment to every use site explaining why using + /// `const_eval_validated` isn't sufficient. The returned constant also isn't in a suitable + /// form to be used outside of const eval. + query const_eval_raw(key: ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>) + -> ConstEvalRawResult<'tcx> { + desc { |tcx| + "const-evaluating `{}`", + key.value.display(tcx) + } + } + + /// Results of evaluating const items or constants embedded in + /// other items (such as enum variant explicit discriminants). + /// + /// In contrast to `const_eval_raw` this performs some validation on the constant, and + /// returns a proper constant that is usable by the rest of the compiler. + /// + /// **Do not use this** directly, use one of the following wrappers: `tcx.const_eval_poly`, + /// `tcx.const_eval_resolve`, `tcx.const_eval_instance`, or `tcx.const_eval_global_id`. + query const_eval_validated(key: ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>) + -> ConstEvalResult<'tcx> { + desc { |tcx| + "const-evaluating + checking `{}`", + key.value.display(tcx) + } + cache_on_disk_if(_, opt_result) { + // Only store results without errors + opt_result.map_or(true, |r| r.is_ok()) + } + } + + /// Destructure a constant ADT or array into its variant index and its + /// field values. + query destructure_const( + key: ty::ParamEnvAnd<'tcx, &'tcx ty::Const<'tcx>> + ) -> mir::DestructuredConst<'tcx> { + desc { "destructure constant" } + } + + query const_caller_location(key: (rustc_span::Symbol, u32, u32)) -> ConstValue<'tcx> { + desc { "get a &core::panic::Location referring to a span" } + } + + query lit_to_const( + key: LitToConstInput<'tcx> + ) -> Result<&'tcx ty::Const<'tcx>, LitToConstError> { + desc { "converting literal to const" } + } + } + + TypeChecking { + query check_match(key: DefId) { + desc { |tcx| "match-checking `{}`", tcx.def_path_str(key) } + cache_on_disk_if { key.is_local() } + } + + /// Performs part of the privacy check and computes "access levels". + query privacy_access_levels(_: CrateNum) -> &'tcx AccessLevels { + eval_always + desc { "privacy access levels" } + } + query check_private_in_public(_: CrateNum) -> () { + eval_always + desc { "checking for private elements in public interfaces" } + } + } + + Other { + query reachable_set(_: CrateNum) -> FxHashSet<LocalDefId> { + storage(ArenaCacheSelector<'tcx>) + desc { "reachability" } + } + + /// Per-body `region::ScopeTree`. The `DefId` should be the owner `DefId` for the body; + /// in the case of closures, this will be redirected to the enclosing function. + query region_scope_tree(def_id: DefId) -> &'tcx region::ScopeTree { + desc { |tcx| "computing drop scopes for `{}`", tcx.def_path_str(def_id) } + } + + query mir_shims(key: ty::InstanceDef<'tcx>) -> mir::Body<'tcx> { + storage(ArenaCacheSelector<'tcx>) + desc { |tcx| "generating MIR shim for `{}`", tcx.def_path_str(key.def_id()) } + } + + /// The `symbol_name` query provides the symbol name for calling a + /// given instance from the local crate. In particular, it will also + /// look up the correct symbol name of instances from upstream crates. + query symbol_name(key: ty::Instance<'tcx>) -> ty::SymbolName<'tcx> { + desc { "computing the symbol for `{}`", key } + cache_on_disk_if { true } + } + + query def_kind(def_id: DefId) -> DefKind { + desc { |tcx| "looking up definition kind of `{}`", tcx.def_path_str(def_id) } + } + query def_span(def_id: DefId) -> Span { + desc { |tcx| "looking up span for `{}`", tcx.def_path_str(def_id) } + // FIXME(mw): DefSpans are not really inputs since they are derived from + // HIR. But at the moment HIR hashing still contains some hacks that allow + // to make type debuginfo to be source location independent. Declaring + // DefSpan an input makes sure that changes to these are always detected + // regardless of HIR hashing. + eval_always + } + query lookup_stability(def_id: DefId) -> Option<&'tcx attr::Stability> { + desc { |tcx| "looking up stability of `{}`", tcx.def_path_str(def_id) } + } + query lookup_const_stability(def_id: DefId) -> Option<&'tcx attr::ConstStability> { + desc { |tcx| "looking up const stability of `{}`", tcx.def_path_str(def_id) } + } + query lookup_deprecation_entry(def_id: DefId) -> Option<DeprecationEntry> { + desc { |tcx| "checking whether `{}` is deprecated", tcx.def_path_str(def_id) } + } + query item_attrs(def_id: DefId) -> &'tcx [ast::Attribute] { + desc { |tcx| "collecting attributes of `{}`", tcx.def_path_str(def_id) } + } + } + + Codegen { + query codegen_fn_attrs(def_id: DefId) -> CodegenFnAttrs { + desc { |tcx| "computing codegen attributes of `{}`", tcx.def_path_str(def_id) } + storage(ArenaCacheSelector<'tcx>) + cache_on_disk_if { true } + } + } + + Other { + query fn_arg_names(def_id: DefId) -> &'tcx [rustc_span::symbol::Ident] { + desc { |tcx| "looking up function parameter names for `{}`", tcx.def_path_str(def_id) } + } + /// Gets the rendered value of the specified constant or associated constant. + /// Used by rustdoc. + query rendered_const(def_id: DefId) -> String { + desc { |tcx| "rendering constant intializer of `{}`", tcx.def_path_str(def_id) } + } + query impl_parent(def_id: DefId) -> Option<DefId> { + desc { |tcx| "computing specialization parent impl of `{}`", tcx.def_path_str(def_id) } + } + } + + TypeChecking { + query trait_of_item(def_id: DefId) -> Option<DefId> { + desc { |tcx| "finding trait defining `{}`", tcx.def_path_str(def_id) } + } + } + + Codegen { + query is_mir_available(key: DefId) -> bool { + desc { |tcx| "checking if item has mir available: `{}`", tcx.def_path_str(key) } + } + } + + Other { + query vtable_methods(key: ty::PolyTraitRef<'tcx>) + -> &'tcx [Option<(DefId, SubstsRef<'tcx>)>] { + desc { |tcx| "finding all methods for trait {}", tcx.def_path_str(key.def_id()) } + } + } + + Codegen { + query codegen_fulfill_obligation( + key: (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>) + ) -> Result<ImplSource<'tcx, ()>, ErrorReported> { + cache_on_disk_if { true } + desc { |tcx| + "checking if `{}` fulfills its obligations", + tcx.def_path_str(key.1.def_id()) + } + } + } + + TypeChecking { + query all_local_trait_impls(key: CrateNum) -> &'tcx BTreeMap<DefId, Vec<hir::HirId>> { + desc { "local trait impls" } + } + query trait_impls_of(key: DefId) -> ty::trait_def::TraitImpls { + storage(ArenaCacheSelector<'tcx>) + desc { |tcx| "trait impls of `{}`", tcx.def_path_str(key) } + } + query specialization_graph_of(key: DefId) -> specialization_graph::Graph { + storage(ArenaCacheSelector<'tcx>) + desc { |tcx| "building specialization graph of trait `{}`", tcx.def_path_str(key) } + cache_on_disk_if { true } + } + query object_safety_violations(key: DefId) -> &'tcx [traits::ObjectSafetyViolation] { + desc { |tcx| "determine object safety of trait `{}`", tcx.def_path_str(key) } + } + + /// Gets the ParameterEnvironment for a given item; this environment + /// will be in "user-facing" mode, meaning that it is suitable for + /// type-checking etc, and it does not normalize specializable + /// associated types. This is almost always what you want, + /// unless you are doing MIR optimizations, in which case you + query param_env(def_id: DefId) -> ty::ParamEnv<'tcx> { + desc { |tcx| "computing normalized predicates of `{}`", tcx.def_path_str(def_id) } + } + + /// Like `param_env`, but returns the `ParamEnv in `Reveal::All` mode. + /// Prefer this over `tcx.param_env(def_id).with_reveal_all_normalized(tcx)`, + /// as this method is more efficient. + query param_env_reveal_all_normalized(def_id: DefId) -> ty::ParamEnv<'tcx> { + desc { |tcx| "computing revealed normalized predicates of `{}`", tcx.def_path_str(def_id) } + } + + /// Trait selection queries. These are best used by invoking `ty.is_copy_modulo_regions()`, + /// `ty.is_copy()`, etc, since that will prune the environment where possible. + query is_copy_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { + desc { "computing whether `{}` is `Copy`", env.value } + } + /// Query backing `TyS::is_sized`. + query is_sized_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { + desc { "computing whether `{}` is `Sized`", env.value } + } + /// Query backing `TyS::is_freeze`. + query is_freeze_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { + desc { "computing whether `{}` is freeze", env.value } + } + /// Query backing `TyS::needs_drop`. + query needs_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { + desc { "computing whether `{}` needs drop", env.value } + } + + /// Query backing `TyS::is_structural_eq_shallow`. + /// + /// This is only correct for ADTs. Call `is_structural_eq_shallow` to handle all types + /// correctly. + query has_structural_eq_impls(ty: Ty<'tcx>) -> bool { + desc { + "computing whether `{:?}` implements `PartialStructuralEq` and `StructuralEq`", + ty + } + } + + /// A list of types where the ADT requires drop if and only if any of + /// those types require drop. If the ADT is known to always need drop + /// then `Err(AlwaysRequiresDrop)` is returned. + query adt_drop_tys(def_id: DefId) -> Result<&'tcx ty::List<Ty<'tcx>>, AlwaysRequiresDrop> { + desc { |tcx| "computing when `{}` needs drop", tcx.def_path_str(def_id) } + cache_on_disk_if { true } + } + + query layout_raw( + env: ty::ParamEnvAnd<'tcx, Ty<'tcx>> + ) -> Result<&'tcx rustc_target::abi::Layout, ty::layout::LayoutError<'tcx>> { + desc { "computing layout of `{}`", env.value } + } + } + + Other { + query dylib_dependency_formats(_: CrateNum) + -> &'tcx [(CrateNum, LinkagePreference)] { + desc { "dylib dependency formats of crate" } + } + + query dependency_formats(_: CrateNum) + -> Lrc<crate::middle::dependency_format::Dependencies> + { + desc { "get the linkage format of all dependencies" } + } + } + + Codegen { + query is_compiler_builtins(_: CrateNum) -> bool { + fatal_cycle + desc { "checking if the crate is_compiler_builtins" } + } + query has_global_allocator(_: CrateNum) -> bool { + fatal_cycle + desc { "checking if the crate has_global_allocator" } + } + query has_panic_handler(_: CrateNum) -> bool { + fatal_cycle + desc { "checking if the crate has_panic_handler" } + } + query is_profiler_runtime(_: CrateNum) -> bool { + fatal_cycle + desc { "query a crate is `#![profiler_runtime]`" } + } + query panic_strategy(_: CrateNum) -> PanicStrategy { + fatal_cycle + desc { "query a crate's configured panic strategy" } + } + query is_no_builtins(_: CrateNum) -> bool { + fatal_cycle + desc { "test whether a crate has `#![no_builtins]`" } + } + query symbol_mangling_version(_: CrateNum) -> SymbolManglingVersion { + fatal_cycle + desc { "query a crate's symbol mangling version" } + } + + query extern_crate(def_id: DefId) -> Option<&'tcx ExternCrate> { + eval_always + desc { "getting crate's ExternCrateData" } + } + } + + TypeChecking { + query specializes(_: (DefId, DefId)) -> bool { + desc { "computing whether impls specialize one another" } + } + query in_scope_traits_map(_: LocalDefId) + -> Option<&'tcx FxHashMap<ItemLocalId, StableVec<TraitCandidate>>> { + eval_always + desc { "traits in scope at a block" } + } + } + + Other { + query module_exports(def_id: LocalDefId) -> Option<&'tcx [Export<LocalDefId>]> { + desc { |tcx| "looking up items exported by `{}`", tcx.def_path_str(def_id.to_def_id()) } + eval_always + } + } + + TypeChecking { + query impl_defaultness(def_id: DefId) -> hir::Defaultness { + desc { |tcx| "looking up whether `{}` is a default impl", tcx.def_path_str(def_id) } + } + + query check_item_well_formed(key: LocalDefId) -> () { + desc { |tcx| "checking that `{}` is well-formed", tcx.def_path_str(key.to_def_id()) } + } + query check_trait_item_well_formed(key: LocalDefId) -> () { + desc { |tcx| "checking that `{}` is well-formed", tcx.def_path_str(key.to_def_id()) } + } + query check_impl_item_well_formed(key: LocalDefId) -> () { + desc { |tcx| "checking that `{}` is well-formed", tcx.def_path_str(key.to_def_id()) } + } + } + + + Linking { + // The `DefId`s of all non-generic functions and statics in the given crate + // that can be reached from outside the crate. + // + // We expect this items to be available for being linked to. + // + // This query can also be called for `LOCAL_CRATE`. In this case it will + // compute which items will be reachable to other crates, taking into account + // the kind of crate that is currently compiled. Crates with only a + // C interface have fewer reachable things. + // + // Does not include external symbols that don't have a corresponding DefId, + // like the compiler-generated `main` function and so on. + query reachable_non_generics(_: CrateNum) + -> DefIdMap<SymbolExportLevel> { + storage(ArenaCacheSelector<'tcx>) + desc { "looking up the exported symbols of a crate" } + } + query is_reachable_non_generic(def_id: DefId) -> bool { + desc { |tcx| "checking whether `{}` is an exported symbol", tcx.def_path_str(def_id) } + } + query is_unreachable_local_definition(def_id: DefId) -> bool { + desc { |tcx| + "checking whether `{}` is reachable from outside the crate", + tcx.def_path_str(def_id), + } + } + } + + Codegen { + /// The entire set of monomorphizations the local crate can safely link + /// to because they are exported from upstream crates. Do not depend on + /// this directly, as its value changes anytime a monomorphization gets + /// added or removed in any upstream crate. Instead use the narrower + /// `upstream_monomorphizations_for`, `upstream_drop_glue_for`, or, even + /// better, `Instance::upstream_monomorphization()`. + query upstream_monomorphizations( + k: CrateNum + ) -> DefIdMap<FxHashMap<SubstsRef<'tcx>, CrateNum>> { + storage(ArenaCacheSelector<'tcx>) + desc { "collecting available upstream monomorphizations `{:?}`", k } + } + + /// Returns the set of upstream monomorphizations available for the + /// generic function identified by the given `def_id`. The query makes + /// sure to make a stable selection if the same monomorphization is + /// available in multiple upstream crates. + /// + /// You likely want to call `Instance::upstream_monomorphization()` + /// instead of invoking this query directly. + query upstream_monomorphizations_for(def_id: DefId) + -> Option<&'tcx FxHashMap<SubstsRef<'tcx>, CrateNum>> { + desc { |tcx| + "collecting available upstream monomorphizations for `{}`", + tcx.def_path_str(def_id), + } + } + + /// Returns the upstream crate that exports drop-glue for the given + /// type (`substs` is expected to be a single-item list containing the + /// type one wants drop-glue for). + /// + /// This is a subset of `upstream_monomorphizations_for` in order to + /// increase dep-tracking granularity. Otherwise adding or removing any + /// type with drop-glue in any upstream crate would invalidate all + /// functions calling drop-glue of an upstream type. + /// + /// You likely want to call `Instance::upstream_monomorphization()` + /// instead of invoking this query directly. + /// + /// NOTE: This query could easily be extended to also support other + /// common functions that have are large set of monomorphizations + /// (like `Clone::clone` for example). + query upstream_drop_glue_for(substs: SubstsRef<'tcx>) -> Option<CrateNum> { + desc { "available upstream drop-glue for `{:?}`", substs } + } + } + + Other { + query foreign_modules(_: CrateNum) -> &'tcx [ForeignModule] { + desc { "looking up the foreign modules of a linked crate" } + } + + /// Identifies the entry-point (e.g., the `main` function) for a given + /// crate, returning `None` if there is no entry point (such as for library crates). + query entry_fn(_: CrateNum) -> Option<(LocalDefId, EntryFnType)> { + desc { "looking up the entry function of a crate" } + } + query plugin_registrar_fn(_: CrateNum) -> Option<DefId> { + desc { "looking up the plugin registrar for a crate" } + } + query proc_macro_decls_static(_: CrateNum) -> Option<DefId> { + desc { "looking up the derive registrar for a crate" } + } + query crate_disambiguator(_: CrateNum) -> CrateDisambiguator { + eval_always + desc { "looking up the disambiguator a crate" } + } + query crate_hash(_: CrateNum) -> Svh { + eval_always + desc { "looking up the hash a crate" } + } + query crate_host_hash(_: CrateNum) -> Option<Svh> { + eval_always + desc { "looking up the hash of a host version of a crate" } + } + query original_crate_name(_: CrateNum) -> Symbol { + eval_always + desc { "looking up the original name a crate" } + } + query extra_filename(_: CrateNum) -> String { + eval_always + desc { "looking up the extra filename for a crate" } + } + query crate_extern_paths(_: CrateNum) -> Vec<PathBuf> { + eval_always + desc { "looking up the paths for extern crates" } + } + } + + TypeChecking { + query implementations_of_trait(_: (CrateNum, DefId)) + -> &'tcx [(DefId, Option<ty::fast_reject::SimplifiedType>)] { + desc { "looking up implementations of a trait in a crate" } + } + query all_trait_implementations(_: CrateNum) + -> &'tcx [(DefId, Option<ty::fast_reject::SimplifiedType>)] { + desc { "looking up all (?) trait implementations" } + } + } + + Other { + query dllimport_foreign_items(_: CrateNum) + -> FxHashSet<DefId> { + storage(ArenaCacheSelector<'tcx>) + desc { "dllimport_foreign_items" } + } + query is_dllimport_foreign_item(def_id: DefId) -> bool { + desc { |tcx| "is_dllimport_foreign_item({})", tcx.def_path_str(def_id) } + } + query is_statically_included_foreign_item(def_id: DefId) -> bool { + desc { |tcx| "is_statically_included_foreign_item({})", tcx.def_path_str(def_id) } + } + query native_library_kind(def_id: DefId) + -> Option<NativeLibKind> { + desc { |tcx| "native_library_kind({})", tcx.def_path_str(def_id) } + } + } + + Linking { + query link_args(_: CrateNum) -> Lrc<Vec<String>> { + eval_always + desc { "looking up link arguments for a crate" } + } + } + + BorrowChecking { + /// Lifetime resolution. See `middle::resolve_lifetimes`. + query resolve_lifetimes(_: CrateNum) -> ResolveLifetimes { + storage(ArenaCacheSelector<'tcx>) + desc { "resolving lifetimes" } + } + query named_region_map(_: LocalDefId) -> + Option<&'tcx FxHashMap<ItemLocalId, Region>> { + desc { "looking up a named region" } + } + query is_late_bound_map(_: LocalDefId) -> + Option<&'tcx FxHashSet<ItemLocalId>> { + desc { "testing if a region is late bound" } + } + query object_lifetime_defaults_map(_: LocalDefId) + -> Option<&'tcx FxHashMap<ItemLocalId, Vec<ObjectLifetimeDefault>>> { + desc { "looking up lifetime defaults for a region" } + } + } + + TypeChecking { + query visibility(def_id: DefId) -> ty::Visibility { + desc { |tcx| "computing visibility of `{}`", tcx.def_path_str(def_id) } + } + } + + Other { + query dep_kind(_: CrateNum) -> CrateDepKind { + eval_always + desc { "fetching what a dependency looks like" } + } + query crate_name(_: CrateNum) -> Symbol { + eval_always + desc { "fetching what a crate is named" } + } + query item_children(def_id: DefId) -> &'tcx [Export<hir::HirId>] { + desc { |tcx| "collecting child items of `{}`", tcx.def_path_str(def_id) } + } + query extern_mod_stmt_cnum(def_id: LocalDefId) -> Option<CrateNum> { + desc { |tcx| "computing crate imported by `{}`", tcx.def_path_str(def_id.to_def_id()) } + } + + query get_lib_features(_: CrateNum) -> LibFeatures { + storage(ArenaCacheSelector<'tcx>) + eval_always + desc { "calculating the lib features map" } + } + query defined_lib_features(_: CrateNum) + -> &'tcx [(Symbol, Option<Symbol>)] { + desc { "calculating the lib features defined in a crate" } + } + /// Returns the lang items defined in another crate by loading it from metadata. + // FIXME: It is illegal to pass a `CrateNum` other than `LOCAL_CRATE` here, just get rid + // of that argument? + query get_lang_items(_: CrateNum) -> LanguageItems { + storage(ArenaCacheSelector<'tcx>) + eval_always + desc { "calculating the lang items map" } + } + + /// Returns all diagnostic items defined in all crates. + query all_diagnostic_items(_: CrateNum) -> FxHashMap<Symbol, DefId> { + storage(ArenaCacheSelector<'tcx>) + eval_always + desc { "calculating the diagnostic items map" } + } + + /// Returns the lang items defined in another crate by loading it from metadata. + query defined_lang_items(_: CrateNum) -> &'tcx [(DefId, usize)] { + desc { "calculating the lang items defined in a crate" } + } + + /// Returns the diagnostic items defined in a crate. + query diagnostic_items(_: CrateNum) -> FxHashMap<Symbol, DefId> { + storage(ArenaCacheSelector<'tcx>) + desc { "calculating the diagnostic items map in a crate" } + } + + query missing_lang_items(_: CrateNum) -> &'tcx [LangItem] { + desc { "calculating the missing lang items in a crate" } + } + query visible_parent_map(_: CrateNum) + -> DefIdMap<DefId> { + storage(ArenaCacheSelector<'tcx>) + desc { "calculating the visible parent map" } + } + query missing_extern_crate_item(_: CrateNum) -> bool { + eval_always + desc { "seeing if we're missing an `extern crate` item for this crate" } + } + query used_crate_source(_: CrateNum) -> Lrc<CrateSource> { + eval_always + desc { "looking at the source for a crate" } + } + query postorder_cnums(_: CrateNum) -> &'tcx [CrateNum] { + eval_always + desc { "generating a postorder list of CrateNums" } + } + + query upvars_mentioned(def_id: DefId) -> Option<&'tcx FxIndexMap<hir::HirId, hir::Upvar>> { + desc { |tcx| "collecting upvars mentioned in `{}`", tcx.def_path_str(def_id) } + eval_always + } + query maybe_unused_trait_import(def_id: LocalDefId) -> bool { + eval_always + desc { |tcx| "maybe_unused_trait_import for `{}`", tcx.def_path_str(def_id.to_def_id()) } + } + query maybe_unused_extern_crates(_: CrateNum) + -> &'tcx [(LocalDefId, Span)] { + eval_always + desc { "looking up all possibly unused extern crates" } + } + query names_imported_by_glob_use(def_id: LocalDefId) + -> &'tcx FxHashSet<Symbol> { + eval_always + desc { |tcx| "names_imported_by_glob_use for `{}`", tcx.def_path_str(def_id.to_def_id()) } + } + + query stability_index(_: CrateNum) -> stability::Index<'tcx> { + storage(ArenaCacheSelector<'tcx>) + eval_always + desc { "calculating the stability index for the local crate" } + } + query all_crate_nums(_: CrateNum) -> &'tcx [CrateNum] { + eval_always + desc { "fetching all foreign CrateNum instances" } + } + + /// A vector of every trait accessible in the whole crate + /// (i.e., including those from subcrates). This is used only for + /// error reporting. + query all_traits(_: CrateNum) -> &'tcx [DefId] { + desc { "fetching all foreign and local traits" } + } + } + + Linking { + /// The list of symbols exported from the given crate. + /// + /// - All names contained in `exported_symbols(cnum)` are guaranteed to + /// correspond to a publicly visible symbol in `cnum` machine code. + /// - The `exported_symbols` sets of different crates do not intersect. + query exported_symbols(_: CrateNum) + -> &'tcx [(ExportedSymbol<'tcx>, SymbolExportLevel)] { + desc { "exported_symbols" } + } + } + + Codegen { + query collect_and_partition_mono_items(_: CrateNum) + -> (&'tcx DefIdSet, &'tcx [CodegenUnit<'tcx>]) { + eval_always + desc { "collect_and_partition_mono_items" } + } + query is_codegened_item(def_id: DefId) -> bool { + desc { |tcx| "determining whether `{}` needs codegen", tcx.def_path_str(def_id) } + } + query codegen_unit(_: Symbol) -> &'tcx CodegenUnit<'tcx> { + desc { "codegen_unit" } + } + query unused_generic_params(key: DefId) -> FiniteBitSet<u32> { + cache_on_disk_if { key.is_local() } + desc { + |tcx| "determining which generic parameters are unused by `{}`", + tcx.def_path_str(key) + } + } + query backend_optimization_level(_: CrateNum) -> OptLevel { + desc { "optimization level used by backend" } + } + } + + Other { + query output_filenames(_: CrateNum) -> Arc<OutputFilenames> { + eval_always + desc { "output_filenames" } + } + } + + TypeChecking { + /// Do not call this query directly: invoke `normalize` instead. + query normalize_projection_ty( + goal: CanonicalProjectionGoal<'tcx> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, NormalizationResult<'tcx>>>, + NoSolution, + > { + desc { "normalizing `{:?}`", goal } + } + + /// Do not call this query directly: invoke `normalize_erasing_regions` instead. + query normalize_generic_arg_after_erasing_regions( + goal: ParamEnvAnd<'tcx, GenericArg<'tcx>> + ) -> GenericArg<'tcx> { + desc { "normalizing `{}`", goal.value } + } + + query implied_outlives_bounds( + goal: CanonicalTyGoal<'tcx> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Vec<OutlivesBound<'tcx>>>>, + NoSolution, + > { + desc { "computing implied outlives bounds for `{:?}`", goal } + } + + /// Do not call this query directly: invoke `infcx.at().dropck_outlives()` instead. + query dropck_outlives( + goal: CanonicalTyGoal<'tcx> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, DropckOutlivesResult<'tcx>>>, + NoSolution, + > { + desc { "computing dropck types for `{:?}`", goal } + } + + /// Do not call this query directly: invoke `infcx.predicate_may_hold()` or + /// `infcx.predicate_must_hold()` instead. + query evaluate_obligation( + goal: CanonicalPredicateGoal<'tcx> + ) -> Result<traits::EvaluationResult, traits::OverflowError> { + desc { "evaluating trait selection obligation `{}`", goal.value.value } + } + + query evaluate_goal( + goal: traits::ChalkCanonicalGoal<'tcx> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>, + NoSolution + > { + desc { "evaluating trait selection obligation `{}`", goal.value } + } + + query type_implements_trait( + key: (DefId, Ty<'tcx>, SubstsRef<'tcx>, ty::ParamEnv<'tcx>, ) + ) -> bool { + desc { "evaluating `type_implements_trait` `{:?}`", key } + } + + /// Do not call this query directly: part of the `Eq` type-op + query type_op_ascribe_user_type( + goal: CanonicalTypeOpAscribeUserTypeGoal<'tcx> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>, + NoSolution, + > { + desc { "evaluating `type_op_ascribe_user_type` `{:?}`", goal } + } + + /// Do not call this query directly: part of the `Eq` type-op + query type_op_eq( + goal: CanonicalTypeOpEqGoal<'tcx> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>, + NoSolution, + > { + desc { "evaluating `type_op_eq` `{:?}`", goal } + } + + /// Do not call this query directly: part of the `Subtype` type-op + query type_op_subtype( + goal: CanonicalTypeOpSubtypeGoal<'tcx> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>, + NoSolution, + > { + desc { "evaluating `type_op_subtype` `{:?}`", goal } + } + + /// Do not call this query directly: part of the `ProvePredicate` type-op + query type_op_prove_predicate( + goal: CanonicalTypeOpProvePredicateGoal<'tcx> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>, + NoSolution, + > { + desc { "evaluating `type_op_prove_predicate` `{:?}`", goal } + } + + /// Do not call this query directly: part of the `Normalize` type-op + query type_op_normalize_ty( + goal: CanonicalTypeOpNormalizeGoal<'tcx, Ty<'tcx>> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Ty<'tcx>>>, + NoSolution, + > { + desc { "normalizing `{:?}`", goal } + } + + /// Do not call this query directly: part of the `Normalize` type-op + query type_op_normalize_predicate( + goal: CanonicalTypeOpNormalizeGoal<'tcx, ty::Predicate<'tcx>> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ty::Predicate<'tcx>>>, + NoSolution, + > { + desc { "normalizing `{:?}`", goal } + } + + /// Do not call this query directly: part of the `Normalize` type-op + query type_op_normalize_poly_fn_sig( + goal: CanonicalTypeOpNormalizeGoal<'tcx, ty::PolyFnSig<'tcx>> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ty::PolyFnSig<'tcx>>>, + NoSolution, + > { + desc { "normalizing `{:?}`", goal } + } + + /// Do not call this query directly: part of the `Normalize` type-op + query type_op_normalize_fn_sig( + goal: CanonicalTypeOpNormalizeGoal<'tcx, ty::FnSig<'tcx>> + ) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ty::FnSig<'tcx>>>, + NoSolution, + > { + desc { "normalizing `{:?}`", goal } + } + + query subst_and_check_impossible_predicates(key: (DefId, SubstsRef<'tcx>)) -> bool { + desc { |tcx| + "impossible substituted predicates:`{}`", + tcx.def_path_str(key.0) + } + } + + query method_autoderef_steps( + goal: CanonicalTyGoal<'tcx> + ) -> MethodAutoderefStepsResult<'tcx> { + desc { "computing autoderef types for `{:?}`", goal } + } + } + + Other { + query supported_target_features(_: CrateNum) -> FxHashMap<String, Option<Symbol>> { + storage(ArenaCacheSelector<'tcx>) + eval_always + desc { "looking up supported target features" } + } + + // Get an estimate of the size of an InstanceDef based on its MIR for CGU partitioning. + query instance_def_size_estimate(def: ty::InstanceDef<'tcx>) + -> usize { + desc { |tcx| "estimating size for `{}`", tcx.def_path_str(def.def_id()) } + } + + query features_query(_: CrateNum) -> &'tcx rustc_feature::Features { + eval_always + desc { "looking up enabled feature gates" } + } + + /// Attempt to resolve the given `DefId` to an `Instance`, for the + /// given generics args (`SubstsRef`), returning one of: + /// * `Ok(Some(instance))` on success + /// * `Ok(None)` when the `SubstsRef` are still too generic, + /// and therefore don't allow finding the final `Instance` + /// * `Err(ErrorReported)` when the `Instance` resolution process + /// couldn't complete due to errors elsewhere - this is distinct + /// from `Ok(None)` to avoid misleading diagnostics when an error + /// has already been/will be emitted, for the original cause + query resolve_instance( + key: ty::ParamEnvAnd<'tcx, (DefId, SubstsRef<'tcx>)> + ) -> Result<Option<ty::Instance<'tcx>>, ErrorReported> { + desc { "resolving instance `{}`", ty::Instance::new(key.value.0, key.value.1) } + } + + query resolve_instance_of_const_arg( + key: ty::ParamEnvAnd<'tcx, (LocalDefId, DefId, SubstsRef<'tcx>)> + ) -> Result<Option<ty::Instance<'tcx>>, ErrorReported> { + desc { + "resolving instance of the const argument `{}`", + ty::Instance::new(key.value.0.to_def_id(), key.value.2), + } + } + + query normalize_opaque_types(key: &'tcx ty::List<ty::Predicate<'tcx>>) -> &'tcx ty::List<ty::Predicate<'tcx>> { + desc { "normalizing opaque types in {:?}", key } + } + } +} diff --git a/compiler/rustc_middle/src/tests.rs b/compiler/rustc_middle/src/tests.rs new file mode 100644 index 00000000000..757e0bd3bfb --- /dev/null +++ b/compiler/rustc_middle/src/tests.rs @@ -0,0 +1,13 @@ +use super::*; + +// FIXME(#27438): right now the unit tests of librustc_middle don't refer to any actual +// functions generated in librustc_data_structures (all +// references are through generic functions), but statics are +// referenced from time to time. Due to this bug we won't +// actually correctly link in the statics unless we also +// reference a function, so be sure to reference a dummy +// function. +#[test] +fn noop() { + rustc_data_structures::__noop_fix_for_27438(); +} diff --git a/compiler/rustc_middle/src/traits/chalk.rs b/compiler/rustc_middle/src/traits/chalk.rs new file mode 100644 index 00000000000..405af8cb240 --- /dev/null +++ b/compiler/rustc_middle/src/traits/chalk.rs @@ -0,0 +1,362 @@ +//! Types required for Chalk-related queries +//! +//! The primary purpose of this file is defining an implementation for the +//! `chalk_ir::interner::Interner` trait. The primary purpose of this trait, as +//! its name suggest, is to provide an abstraction boundary for creating +//! interned Chalk types. + +use rustc_middle::mir::interpret::ConstValue; +use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor}; +use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt}; + +use rustc_hir::def_id::DefId; +use rustc_target::spec::abi::Abi; + +use smallvec::SmallVec; + +use std::cmp::Ordering; +use std::fmt; +use std::hash::{Hash, Hasher}; + +#[derive(Copy, Clone)] +pub struct RustInterner<'tcx> { + pub tcx: TyCtxt<'tcx>, +} + +/// We don't ever actually need this. It's only required for derives. +impl<'tcx> Hash for RustInterner<'tcx> { + fn hash<H: Hasher>(&self, _state: &mut H) {} +} + +/// We don't ever actually need this. It's only required for derives. +impl<'tcx> Ord for RustInterner<'tcx> { + fn cmp(&self, _other: &Self) -> Ordering { + Ordering::Equal + } +} + +/// We don't ever actually need this. It's only required for derives. +impl<'tcx> PartialOrd for RustInterner<'tcx> { + fn partial_cmp(&self, _other: &Self) -> Option<Ordering> { + None + } +} + +/// We don't ever actually need this. It's only required for derives. +impl<'tcx> PartialEq for RustInterner<'tcx> { + fn eq(&self, _other: &Self) -> bool { + false + } +} + +/// We don't ever actually need this. It's only required for derives. +impl<'tcx> Eq for RustInterner<'tcx> {} + +impl fmt::Debug for RustInterner<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "RustInterner") + } +} + +// Right now, there is no interning at all. I was running into problems with +// adding interning in `ty/context.rs` for Chalk types with +// `parallel-compiler = true`. -jackh726 +impl<'tcx> chalk_ir::interner::Interner for RustInterner<'tcx> { + type InternedType = Box<chalk_ir::TyData<Self>>; + type InternedLifetime = Box<chalk_ir::LifetimeData<Self>>; + type InternedConst = Box<chalk_ir::ConstData<Self>>; + type InternedConcreteConst = ConstValue<'tcx>; + type InternedGenericArg = Box<chalk_ir::GenericArgData<Self>>; + type InternedGoal = Box<chalk_ir::GoalData<Self>>; + type InternedGoals = Vec<chalk_ir::Goal<Self>>; + type InternedSubstitution = Vec<chalk_ir::GenericArg<Self>>; + type InternedProgramClause = Box<chalk_ir::ProgramClauseData<Self>>; + type InternedProgramClauses = Vec<chalk_ir::ProgramClause<Self>>; + type InternedQuantifiedWhereClauses = Vec<chalk_ir::QuantifiedWhereClause<Self>>; + type InternedVariableKinds = Vec<chalk_ir::VariableKind<Self>>; + type InternedCanonicalVarKinds = Vec<chalk_ir::CanonicalVarKind<Self>>; + type DefId = DefId; + type InternedAdtId = &'tcx AdtDef; + type Identifier = (); + type FnAbi = Abi; + + fn debug_program_clause_implication( + pci: &chalk_ir::ProgramClauseImplication<Self>, + fmt: &mut fmt::Formatter<'_>, + ) -> Option<fmt::Result> { + let mut write = || { + write!(fmt, "{:?}", pci.consequence)?; + + let conditions = pci.conditions.interned(); + + let conds = conditions.len(); + if conds == 0 { + return Ok(()); + } + + write!(fmt, " :- ")?; + for cond in &conditions[..conds - 1] { + write!(fmt, "{:?}, ", cond)?; + } + write!(fmt, "{:?}", conditions[conds - 1])?; + Ok(()) + }; + Some(write()) + } + + fn debug_application_ty( + application_ty: &chalk_ir::ApplicationTy<Self>, + fmt: &mut fmt::Formatter<'_>, + ) -> Option<fmt::Result> { + let chalk_ir::ApplicationTy { name, substitution } = application_ty; + Some(write!(fmt, "{:?}{:?}", name, chalk_ir::debug::Angle(substitution.interned()))) + } + + fn debug_substitution( + substitution: &chalk_ir::Substitution<Self>, + fmt: &mut fmt::Formatter<'_>, + ) -> Option<fmt::Result> { + Some(write!(fmt, "{:?}", substitution.interned())) + } + + fn debug_separator_trait_ref( + separator_trait_ref: &chalk_ir::SeparatorTraitRef<'_, Self>, + fmt: &mut fmt::Formatter<'_>, + ) -> Option<fmt::Result> { + let substitution = &separator_trait_ref.trait_ref.substitution; + let parameters = substitution.interned(); + Some(write!( + fmt, + "{:?}{}{:?}{:?}", + parameters[0], + separator_trait_ref.separator, + separator_trait_ref.trait_ref.trait_id, + chalk_ir::debug::Angle(¶meters[1..]) + )) + } + + fn debug_quantified_where_clauses( + clauses: &chalk_ir::QuantifiedWhereClauses<Self>, + fmt: &mut fmt::Formatter<'_>, + ) -> Option<fmt::Result> { + Some(write!(fmt, "{:?}", clauses.interned())) + } + + fn debug_alias( + alias_ty: &chalk_ir::AliasTy<Self>, + fmt: &mut fmt::Formatter<'_>, + ) -> Option<fmt::Result> { + match alias_ty { + chalk_ir::AliasTy::Projection(projection_ty) => { + Self::debug_projection_ty(projection_ty, fmt) + } + chalk_ir::AliasTy::Opaque(opaque_ty) => Self::debug_opaque_ty(opaque_ty, fmt), + } + } + + fn debug_projection_ty( + projection_ty: &chalk_ir::ProjectionTy<Self>, + fmt: &mut fmt::Formatter<'_>, + ) -> Option<fmt::Result> { + Some(write!( + fmt, + "projection: {:?} {:?}", + projection_ty.associated_ty_id, projection_ty.substitution, + )) + } + + fn debug_opaque_ty( + opaque_ty: &chalk_ir::OpaqueTy<Self>, + fmt: &mut fmt::Formatter<'_>, + ) -> Option<fmt::Result> { + Some(write!(fmt, "{:?}", opaque_ty.opaque_ty_id)) + } + + fn intern_ty(&self, ty: chalk_ir::TyData<Self>) -> Self::InternedType { + Box::new(ty) + } + + fn ty_data<'a>(&self, ty: &'a Self::InternedType) -> &'a chalk_ir::TyData<Self> { + ty + } + + fn intern_lifetime(&self, lifetime: chalk_ir::LifetimeData<Self>) -> Self::InternedLifetime { + Box::new(lifetime) + } + + fn lifetime_data<'a>( + &self, + lifetime: &'a Self::InternedLifetime, + ) -> &'a chalk_ir::LifetimeData<Self> { + &lifetime + } + + fn intern_const(&self, constant: chalk_ir::ConstData<Self>) -> Self::InternedConst { + Box::new(constant) + } + + fn const_data<'a>(&self, constant: &'a Self::InternedConst) -> &'a chalk_ir::ConstData<Self> { + &constant + } + + fn const_eq( + &self, + _ty: &Self::InternedType, + c1: &Self::InternedConcreteConst, + c2: &Self::InternedConcreteConst, + ) -> bool { + c1 == c2 + } + + fn intern_generic_arg(&self, data: chalk_ir::GenericArgData<Self>) -> Self::InternedGenericArg { + Box::new(data) + } + + fn generic_arg_data<'a>( + &self, + data: &'a Self::InternedGenericArg, + ) -> &'a chalk_ir::GenericArgData<Self> { + &data + } + + fn intern_goal(&self, goal: chalk_ir::GoalData<Self>) -> Self::InternedGoal { + Box::new(goal) + } + + fn goal_data<'a>(&self, goal: &'a Self::InternedGoal) -> &'a chalk_ir::GoalData<Self> { + &goal + } + + fn intern_goals<E>( + &self, + data: impl IntoIterator<Item = Result<chalk_ir::Goal<Self>, E>>, + ) -> Result<Self::InternedGoals, E> { + data.into_iter().collect::<Result<Vec<_>, _>>() + } + + fn goals_data<'a>(&self, goals: &'a Self::InternedGoals) -> &'a [chalk_ir::Goal<Self>] { + goals + } + + fn intern_substitution<E>( + &self, + data: impl IntoIterator<Item = Result<chalk_ir::GenericArg<Self>, E>>, + ) -> Result<Self::InternedSubstitution, E> { + data.into_iter().collect::<Result<Vec<_>, _>>() + } + + fn substitution_data<'a>( + &self, + substitution: &'a Self::InternedSubstitution, + ) -> &'a [chalk_ir::GenericArg<Self>] { + substitution + } + + fn intern_program_clause( + &self, + data: chalk_ir::ProgramClauseData<Self>, + ) -> Self::InternedProgramClause { + Box::new(data) + } + + fn program_clause_data<'a>( + &self, + clause: &'a Self::InternedProgramClause, + ) -> &'a chalk_ir::ProgramClauseData<Self> { + &clause + } + + fn intern_program_clauses<E>( + &self, + data: impl IntoIterator<Item = Result<chalk_ir::ProgramClause<Self>, E>>, + ) -> Result<Self::InternedProgramClauses, E> { + data.into_iter().collect::<Result<Vec<_>, _>>() + } + + fn program_clauses_data<'a>( + &self, + clauses: &'a Self::InternedProgramClauses, + ) -> &'a [chalk_ir::ProgramClause<Self>] { + clauses + } + + fn intern_quantified_where_clauses<E>( + &self, + data: impl IntoIterator<Item = Result<chalk_ir::QuantifiedWhereClause<Self>, E>>, + ) -> Result<Self::InternedQuantifiedWhereClauses, E> { + data.into_iter().collect::<Result<Vec<_>, _>>() + } + + fn quantified_where_clauses_data<'a>( + &self, + clauses: &'a Self::InternedQuantifiedWhereClauses, + ) -> &'a [chalk_ir::QuantifiedWhereClause<Self>] { + clauses + } + + fn intern_generic_arg_kinds<E>( + &self, + data: impl IntoIterator<Item = Result<chalk_ir::VariableKind<Self>, E>>, + ) -> Result<Self::InternedVariableKinds, E> { + data.into_iter().collect::<Result<Vec<_>, _>>() + } + + fn variable_kinds_data<'a>( + &self, + parameter_kinds: &'a Self::InternedVariableKinds, + ) -> &'a [chalk_ir::VariableKind<Self>] { + parameter_kinds + } + + fn intern_canonical_var_kinds<E>( + &self, + data: impl IntoIterator<Item = Result<chalk_ir::CanonicalVarKind<Self>, E>>, + ) -> Result<Self::InternedCanonicalVarKinds, E> { + data.into_iter().collect::<Result<Vec<_>, _>>() + } + + fn canonical_var_kinds_data<'a>( + &self, + canonical_var_kinds: &'a Self::InternedCanonicalVarKinds, + ) -> &'a [chalk_ir::CanonicalVarKind<Self>] { + canonical_var_kinds + } +} + +impl<'tcx> chalk_ir::interner::HasInterner for RustInterner<'tcx> { + type Interner = Self; +} + +#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable, TypeFoldable)] +pub enum ChalkEnvironmentClause<'tcx> { + /// A normal rust `ty::Predicate` in the environment. + Predicate(ty::Predicate<'tcx>), + /// A special clause in the environment that gets lowered to + /// `chalk_ir::FromEnv::Ty`. + TypeFromEnv(Ty<'tcx>), +} + +impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ChalkEnvironmentClause<'tcx>> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + let v = self.iter().map(|t| t.fold_with(folder)).collect::<SmallVec<[_; 8]>>(); + folder.tcx().intern_chalk_environment_clause_list(&v) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|t| t.visit_with(visitor)) + } +} +/// We have to elaborate the environment of a chalk goal *before* +/// canonicalization. This type wraps the predicate and the elaborated +/// environment. +#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable, TypeFoldable)] +pub struct ChalkEnvironmentAndGoal<'tcx> { + pub environment: &'tcx ty::List<ChalkEnvironmentClause<'tcx>>, + pub goal: ty::Predicate<'tcx>, +} + +impl<'tcx> fmt::Display for ChalkEnvironmentAndGoal<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "environment: {:?}, goal: {}", self.environment, self.goal) + } +} diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs new file mode 100644 index 00000000000..f86403fa502 --- /dev/null +++ b/compiler/rustc_middle/src/traits/mod.rs @@ -0,0 +1,754 @@ +//! Trait Resolution. See the [rustc dev guide] for more information on how this works. +//! +//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/resolution.html + +mod chalk; +pub mod query; +pub mod select; +pub mod specialization_graph; +mod structural_impls; + +use crate::infer::canonical::Canonical; +use crate::mir::interpret::ErrorHandled; +use crate::ty::subst::SubstsRef; +use crate::ty::{self, AdtKind, Ty, TyCtxt}; + +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_span::symbol::Symbol; +use rustc_span::{Span, DUMMY_SP}; +use smallvec::SmallVec; + +use std::borrow::Cow; +use std::fmt; +use std::ops::Deref; +use std::rc::Rc; + +pub use self::select::{EvaluationCache, EvaluationResult, OverflowError, SelectionCache}; + +pub type ChalkCanonicalGoal<'tcx> = Canonical<'tcx, ChalkEnvironmentAndGoal<'tcx>>; + +pub use self::ImplSource::*; +pub use self::ObligationCauseCode::*; + +pub use self::chalk::{ + ChalkEnvironmentAndGoal, ChalkEnvironmentClause, RustInterner as ChalkRustInterner, +}; + +/// Depending on the stage of compilation, we want projection to be +/// more or less conservative. +#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, HashStable)] +pub enum Reveal { + /// At type-checking time, we refuse to project any associated + /// type that is marked `default`. Non-`default` ("final") types + /// are always projected. This is necessary in general for + /// soundness of specialization. However, we *could* allow + /// projections in fully-monomorphic cases. We choose not to, + /// because we prefer for `default type` to force the type + /// definition to be treated abstractly by any consumers of the + /// impl. Concretely, that means that the following example will + /// fail to compile: + /// + /// ``` + /// trait Assoc { + /// type Output; + /// } + /// + /// impl<T> Assoc for T { + /// default type Output = bool; + /// } + /// + /// fn main() { + /// let <() as Assoc>::Output = true; + /// } + /// ``` + UserFacing, + + /// At codegen time, all monomorphic projections will succeed. + /// Also, `impl Trait` is normalized to the concrete type, + /// which has to be already collected by type-checking. + /// + /// NOTE: as `impl Trait`'s concrete type should *never* + /// be observable directly by the user, `Reveal::All` + /// should not be used by checks which may expose + /// type equality or type contents to the user. + /// There are some exceptions, e.g., around OIBITS and + /// transmute-checking, which expose some details, but + /// not the whole concrete type of the `impl Trait`. + All, +} + +/// The reason why we incurred this obligation; used for error reporting. +/// +/// As the happy path does not care about this struct, storing this on the heap +/// ends up increasing performance. +/// +/// We do not want to intern this as there are a lot of obligation causes which +/// only live for a short period of time. +#[derive(Clone, PartialEq, Eq, Hash, Lift)] +pub struct ObligationCause<'tcx> { + /// `None` for `ObligationCause::dummy`, `Some` otherwise. + data: Option<Rc<ObligationCauseData<'tcx>>>, +} + +const DUMMY_OBLIGATION_CAUSE_DATA: ObligationCauseData<'static> = + ObligationCauseData { span: DUMMY_SP, body_id: hir::CRATE_HIR_ID, code: MiscObligation }; + +// Correctly format `ObligationCause::dummy`. +impl<'tcx> fmt::Debug for ObligationCause<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + ObligationCauseData::fmt(self, f) + } +} + +impl Deref for ObligationCause<'tcx> { + type Target = ObligationCauseData<'tcx>; + + #[inline(always)] + fn deref(&self) -> &Self::Target { + self.data.as_deref().unwrap_or(&DUMMY_OBLIGATION_CAUSE_DATA) + } +} + +#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)] +pub struct ObligationCauseData<'tcx> { + pub span: Span, + + /// The ID of the fn body that triggered this obligation. This is + /// used for region obligations to determine the precise + /// environment in which the region obligation should be evaluated + /// (in particular, closures can add new assumptions). See the + /// field `region_obligations` of the `FulfillmentContext` for more + /// information. + pub body_id: hir::HirId, + + pub code: ObligationCauseCode<'tcx>, +} + +impl<'tcx> ObligationCause<'tcx> { + #[inline] + pub fn new( + span: Span, + body_id: hir::HirId, + code: ObligationCauseCode<'tcx>, + ) -> ObligationCause<'tcx> { + ObligationCause { data: Some(Rc::new(ObligationCauseData { span, body_id, code })) } + } + + pub fn misc(span: Span, body_id: hir::HirId) -> ObligationCause<'tcx> { + ObligationCause::new(span, body_id, MiscObligation) + } + + pub fn dummy_with_span(span: Span) -> ObligationCause<'tcx> { + ObligationCause::new(span, hir::CRATE_HIR_ID, MiscObligation) + } + + #[inline(always)] + pub fn dummy() -> ObligationCause<'tcx> { + ObligationCause { data: None } + } + + pub fn make_mut(&mut self) -> &mut ObligationCauseData<'tcx> { + Rc::make_mut(self.data.get_or_insert_with(|| Rc::new(DUMMY_OBLIGATION_CAUSE_DATA))) + } + + pub fn span(&self, tcx: TyCtxt<'tcx>) -> Span { + match self.code { + ObligationCauseCode::CompareImplMethodObligation { .. } + | ObligationCauseCode::MainFunctionType + | ObligationCauseCode::StartFunctionType => { + tcx.sess.source_map().guess_head_span(self.span) + } + ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause { + arm_span, + .. + }) => arm_span, + _ => self.span, + } + } +} + +#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)] +pub struct UnifyReceiverContext<'tcx> { + pub assoc_item: ty::AssocItem, + pub param_env: ty::ParamEnv<'tcx>, + pub substs: SubstsRef<'tcx>, +} + +#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)] +pub enum ObligationCauseCode<'tcx> { + /// Not well classified or should be obvious from the span. + MiscObligation, + + /// A slice or array is WF only if `T: Sized`. + SliceOrArrayElem, + + /// A tuple is WF only if its middle elements are `Sized`. + TupleElem, + + /// This is the trait reference from the given projection. + ProjectionWf(ty::ProjectionTy<'tcx>), + + /// In an impl of trait `X` for type `Y`, type `Y` must + /// also implement all supertraits of `X`. + ItemObligation(DefId), + + /// Like `ItemObligation`, but with extra detail on the source of the obligation. + BindingObligation(DefId, Span), + + /// A type like `&'a T` is WF only if `T: 'a`. + ReferenceOutlivesReferent(Ty<'tcx>), + + /// A type like `Box<Foo<'a> + 'b>` is WF only if `'b: 'a`. + ObjectTypeBound(Ty<'tcx>, ty::Region<'tcx>), + + /// Obligation incurred due to an object cast. + ObjectCastObligation(/* Object type */ Ty<'tcx>), + + /// Obligation incurred due to a coercion. + Coercion { + source: Ty<'tcx>, + target: Ty<'tcx>, + }, + + /// Various cases where expressions must be `Sized` / `Copy` / etc. + /// `L = X` implies that `L` is `Sized`. + AssignmentLhsSized, + /// `(x1, .., xn)` must be `Sized`. + TupleInitializerSized, + /// `S { ... }` must be `Sized`. + StructInitializerSized, + /// Type of each variable must be `Sized`. + VariableType(hir::HirId), + /// Argument type must be `Sized`. + SizedArgumentType(Option<Span>), + /// Return type must be `Sized`. + SizedReturnType, + /// Yield type must be `Sized`. + SizedYieldType, + /// Inline asm operand type must be `Sized`. + InlineAsmSized, + /// `[T, ..n]` implies that `T` must be `Copy`. + /// If `true`, suggest `const_in_array_repeat_expressions` feature flag. + RepeatVec(bool), + + /// Types of fields (other than the last, except for packed structs) in a struct must be sized. + FieldSized { + adt_kind: AdtKind, + span: Span, + last: bool, + }, + + /// Constant expressions must be sized. + ConstSized, + + /// `static` items must have `Sync` type. + SharedStatic, + + BuiltinDerivedObligation(DerivedObligationCause<'tcx>), + + ImplDerivedObligation(DerivedObligationCause<'tcx>), + + DerivedObligation(DerivedObligationCause<'tcx>), + + /// Error derived when matching traits/impls; see ObligationCause for more details + CompareImplConstObligation, + + /// Error derived when matching traits/impls; see ObligationCause for more details + CompareImplMethodObligation { + item_name: Symbol, + impl_item_def_id: DefId, + trait_item_def_id: DefId, + }, + + /// Error derived when matching traits/impls; see ObligationCause for more details + CompareImplTypeObligation { + item_name: Symbol, + impl_item_def_id: DefId, + trait_item_def_id: DefId, + }, + + /// Checking that this expression can be assigned where it needs to be + // FIXME(eddyb) #11161 is the original Expr required? + ExprAssignable, + + /// Computing common supertype in the arms of a match expression + MatchExpressionArm(Box<MatchExpressionArmCause<'tcx>>), + + /// Type error arising from type checking a pattern against an expected type. + Pattern { + /// The span of the scrutinee or type expression which caused the `root_ty` type. + span: Option<Span>, + /// The root expected type induced by a scrutinee or type expression. + root_ty: Ty<'tcx>, + /// Whether the `Span` came from an expression or a type expression. + origin_expr: bool, + }, + + /// Constants in patterns must have `Structural` type. + ConstPatternStructural, + + /// Computing common supertype in an if expression + IfExpression(Box<IfExpressionCause>), + + /// Computing common supertype of an if expression with no else counter-part + IfExpressionWithNoElse, + + /// `main` has wrong type + MainFunctionType, + + /// `start` has wrong type + StartFunctionType, + + /// Intrinsic has wrong type + IntrinsicType, + + /// Method receiver + MethodReceiver, + + UnifyReceiver(Box<UnifyReceiverContext<'tcx>>), + + /// `return` with no expression + ReturnNoExpression, + + /// `return` with an expression + ReturnValue(hir::HirId), + + /// Return type of this function + ReturnType, + + /// Block implicit return + BlockTailExpression(hir::HirId), + + /// #[feature(trivial_bounds)] is not enabled + TrivialBound, +} + +impl ObligationCauseCode<'_> { + // Return the base obligation, ignoring derived obligations. + pub fn peel_derives(&self) -> &Self { + let mut base_cause = self; + while let BuiltinDerivedObligation(cause) + | ImplDerivedObligation(cause) + | DerivedObligation(cause) = base_cause + { + base_cause = &cause.parent_code; + } + base_cause + } +} + +// `ObligationCauseCode` is used a lot. Make sure it doesn't unintentionally get bigger. +#[cfg(target_arch = "x86_64")] +static_assert_size!(ObligationCauseCode<'_>, 32); + +#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)] +pub struct MatchExpressionArmCause<'tcx> { + pub arm_span: Span, + pub semi_span: Option<Span>, + pub source: hir::MatchSource, + pub prior_arms: Vec<Span>, + pub last_ty: Ty<'tcx>, + pub scrut_hir_id: hir::HirId, +} + +#[derive(Clone, Debug, PartialEq, Eq, Hash)] +pub struct IfExpressionCause { + pub then: Span, + pub outer: Option<Span>, + pub semicolon: Option<Span>, +} + +#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)] +pub struct DerivedObligationCause<'tcx> { + /// The trait reference of the parent obligation that led to the + /// current obligation. Note that only trait obligations lead to + /// derived obligations, so we just store the trait reference here + /// directly. + pub parent_trait_ref: ty::PolyTraitRef<'tcx>, + + /// The parent trait had this cause. + pub parent_code: Rc<ObligationCauseCode<'tcx>>, +} + +#[derive(Clone, Debug, TypeFoldable, Lift)] +pub enum SelectionError<'tcx> { + Unimplemented, + OutputTypeParameterMismatch( + ty::PolyTraitRef<'tcx>, + ty::PolyTraitRef<'tcx>, + ty::error::TypeError<'tcx>, + ), + TraitNotObjectSafe(DefId), + ConstEvalFailure(ErrorHandled), + Overflow, +} + +/// When performing resolution, it is typically the case that there +/// can be one of three outcomes: +/// +/// - `Ok(Some(r))`: success occurred with result `r` +/// - `Ok(None)`: could not definitely determine anything, usually due +/// to inconclusive type inference. +/// - `Err(e)`: error `e` occurred +pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>; + +/// Given the successful resolution of an obligation, the `ImplSource` +/// indicates where the impl comes from. +/// +/// For example, the obligation may be satisfied by a specific impl (case A), +/// or it may be relative to some bound that is in scope (case B). +/// +/// ``` +/// impl<T:Clone> Clone<T> for Option<T> { ... } // Impl_1 +/// impl<T:Clone> Clone<T> for Box<T> { ... } // Impl_2 +/// impl Clone for i32 { ... } // Impl_3 +/// +/// fn foo<T: Clone>(concrete: Option<Box<i32>>, param: T, mixed: Option<T>) { +/// // Case A: Vtable points at a specific impl. Only possible when +/// // type is concretely known. If the impl itself has bounded +/// // type parameters, Vtable will carry resolutions for those as well: +/// concrete.clone(); // Vtable(Impl_1, [Vtable(Impl_2, [Vtable(Impl_3)])]) +/// +/// // Case A: ImplSource points at a specific impl. Only possible when +/// // type is concretely known. If the impl itself has bounded +/// // type parameters, ImplSource will carry resolutions for those as well: +/// concrete.clone(); // ImplSource(Impl_1, [ImplSource(Impl_2, [ImplSource(Impl_3)])]) +/// +/// // Case B: ImplSource must be provided by caller. This applies when +/// // type is a type parameter. +/// param.clone(); // ImplSourceParam +/// +/// // Case C: A mix of cases A and B. +/// mixed.clone(); // ImplSource(Impl_1, [ImplSourceParam]) +/// } +/// ``` +/// +/// ### The type parameter `N` +/// +/// See explanation on `ImplSourceUserDefinedData`. +#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub enum ImplSource<'tcx, N> { + /// ImplSource identifying a particular impl. + ImplSourceUserDefined(ImplSourceUserDefinedData<'tcx, N>), + + /// ImplSource for auto trait implementations. + /// This carries the information and nested obligations with regards + /// to an auto implementation for a trait `Trait`. The nested obligations + /// ensure the trait implementation holds for all the constituent types. + ImplSourceAutoImpl(ImplSourceAutoImplData<N>), + + /// Successful resolution to an obligation provided by the caller + /// for some type parameter. The `Vec<N>` represents the + /// obligations incurred from normalizing the where-clause (if + /// any). + ImplSourceParam(Vec<N>), + + /// Virtual calls through an object. + ImplSourceObject(ImplSourceObjectData<'tcx, N>), + + /// Successful resolution for a builtin trait. + ImplSourceBuiltin(ImplSourceBuiltinData<N>), + + /// ImplSource automatically generated for a closure. The `DefId` is the ID + /// of the closure expression. This is a `ImplSourceUserDefined` in spirit, but the + /// impl is generated by the compiler and does not appear in the source. + ImplSourceClosure(ImplSourceClosureData<'tcx, N>), + + /// Same as above, but for a function pointer type with the given signature. + ImplSourceFnPointer(ImplSourceFnPointerData<'tcx, N>), + + /// ImplSource for a builtin `DeterminantKind` trait implementation. + ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData), + + /// ImplSource automatically generated for a generator. + ImplSourceGenerator(ImplSourceGeneratorData<'tcx, N>), + + /// ImplSource for a trait alias. + ImplSourceTraitAlias(ImplSourceTraitAliasData<'tcx, N>), +} + +impl<'tcx, N> ImplSource<'tcx, N> { + pub fn nested_obligations(self) -> Vec<N> { + match self { + ImplSourceUserDefined(i) => i.nested, + ImplSourceParam(n) => n, + ImplSourceBuiltin(i) => i.nested, + ImplSourceAutoImpl(d) => d.nested, + ImplSourceClosure(c) => c.nested, + ImplSourceGenerator(c) => c.nested, + ImplSourceObject(d) => d.nested, + ImplSourceFnPointer(d) => d.nested, + ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData) => Vec::new(), + ImplSourceTraitAlias(d) => d.nested, + } + } + + pub fn borrow_nested_obligations(&self) -> &[N] { + match &self { + ImplSourceUserDefined(i) => &i.nested[..], + ImplSourceParam(n) => &n[..], + ImplSourceBuiltin(i) => &i.nested[..], + ImplSourceAutoImpl(d) => &d.nested[..], + ImplSourceClosure(c) => &c.nested[..], + ImplSourceGenerator(c) => &c.nested[..], + ImplSourceObject(d) => &d.nested[..], + ImplSourceFnPointer(d) => &d.nested[..], + ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData) => &[], + ImplSourceTraitAlias(d) => &d.nested[..], + } + } + + pub fn map<M, F>(self, f: F) -> ImplSource<'tcx, M> + where + F: FnMut(N) -> M, + { + match self { + ImplSourceUserDefined(i) => ImplSourceUserDefined(ImplSourceUserDefinedData { + impl_def_id: i.impl_def_id, + substs: i.substs, + nested: i.nested.into_iter().map(f).collect(), + }), + ImplSourceParam(n) => ImplSourceParam(n.into_iter().map(f).collect()), + ImplSourceBuiltin(i) => ImplSourceBuiltin(ImplSourceBuiltinData { + nested: i.nested.into_iter().map(f).collect(), + }), + ImplSourceObject(o) => ImplSourceObject(ImplSourceObjectData { + upcast_trait_ref: o.upcast_trait_ref, + vtable_base: o.vtable_base, + nested: o.nested.into_iter().map(f).collect(), + }), + ImplSourceAutoImpl(d) => ImplSourceAutoImpl(ImplSourceAutoImplData { + trait_def_id: d.trait_def_id, + nested: d.nested.into_iter().map(f).collect(), + }), + ImplSourceClosure(c) => ImplSourceClosure(ImplSourceClosureData { + closure_def_id: c.closure_def_id, + substs: c.substs, + nested: c.nested.into_iter().map(f).collect(), + }), + ImplSourceGenerator(c) => ImplSourceGenerator(ImplSourceGeneratorData { + generator_def_id: c.generator_def_id, + substs: c.substs, + nested: c.nested.into_iter().map(f).collect(), + }), + ImplSourceFnPointer(p) => ImplSourceFnPointer(ImplSourceFnPointerData { + fn_ty: p.fn_ty, + nested: p.nested.into_iter().map(f).collect(), + }), + ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData) => { + ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData) + } + ImplSourceTraitAlias(d) => ImplSourceTraitAlias(ImplSourceTraitAliasData { + alias_def_id: d.alias_def_id, + substs: d.substs, + nested: d.nested.into_iter().map(f).collect(), + }), + } + } +} + +/// Identifies a particular impl in the source, along with a set of +/// substitutions from the impl's type/lifetime parameters. The +/// `nested` vector corresponds to the nested obligations attached to +/// the impl's type parameters. +/// +/// The type parameter `N` indicates the type used for "nested +/// obligations" that are required by the impl. During type-check, this +/// is `Obligation`, as one might expect. During codegen, however, this +/// is `()`, because codegen only requires a shallow resolution of an +/// impl, and nested obligations are satisfied later. +#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct ImplSourceUserDefinedData<'tcx, N> { + pub impl_def_id: DefId, + pub substs: SubstsRef<'tcx>, + pub nested: Vec<N>, +} + +#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct ImplSourceGeneratorData<'tcx, N> { + pub generator_def_id: DefId, + pub substs: SubstsRef<'tcx>, + /// Nested obligations. This can be non-empty if the generator + /// signature contains associated types. + pub nested: Vec<N>, +} + +#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct ImplSourceClosureData<'tcx, N> { + pub closure_def_id: DefId, + pub substs: SubstsRef<'tcx>, + /// Nested obligations. This can be non-empty if the closure + /// signature contains associated types. + pub nested: Vec<N>, +} + +#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct ImplSourceAutoImplData<N> { + pub trait_def_id: DefId, + pub nested: Vec<N>, +} + +#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct ImplSourceBuiltinData<N> { + pub nested: Vec<N>, +} + +#[derive(PartialEq, Eq, Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct ImplSourceObjectData<'tcx, N> { + /// `Foo` upcast to the obligation trait. This will be some supertrait of `Foo`. + pub upcast_trait_ref: ty::PolyTraitRef<'tcx>, + + /// The vtable is formed by concatenating together the method lists of + /// the base object trait and all supertraits; this is the start of + /// `upcast_trait_ref`'s methods in that vtable. + pub vtable_base: usize, + + pub nested: Vec<N>, +} + +#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct ImplSourceFnPointerData<'tcx, N> { + pub fn_ty: Ty<'tcx>, + pub nested: Vec<N>, +} + +// FIXME(@lcnr): This should be refactored and merged with other builtin vtables. +#[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] +pub struct ImplSourceDiscriminantKindData; + +#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct ImplSourceTraitAliasData<'tcx, N> { + pub alias_def_id: DefId, + pub substs: SubstsRef<'tcx>, + pub nested: Vec<N>, +} + +#[derive(Clone, Debug, PartialEq, Eq, Hash, HashStable)] +pub enum ObjectSafetyViolation { + /// `Self: Sized` declared on the trait. + SizedSelf(SmallVec<[Span; 1]>), + + /// Supertrait reference references `Self` an in illegal location + /// (e.g., `trait Foo : Bar<Self>`). + SupertraitSelf(SmallVec<[Span; 1]>), + + /// Method has something illegal. + Method(Symbol, MethodViolationCode, Span), + + /// Associated const. + AssocConst(Symbol, Span), +} + +impl ObjectSafetyViolation { + pub fn error_msg(&self) -> Cow<'static, str> { + match *self { + ObjectSafetyViolation::SizedSelf(_) => "it requires `Self: Sized`".into(), + ObjectSafetyViolation::SupertraitSelf(ref spans) => { + if spans.iter().any(|sp| *sp != DUMMY_SP) { + "it uses `Self` as a type parameter in this".into() + } else { + "it cannot use `Self` as a type parameter in a supertrait or `where`-clause" + .into() + } + } + ObjectSafetyViolation::Method(name, MethodViolationCode::StaticMethod(_), _) => { + format!("associated function `{}` has no `self` parameter", name).into() + } + ObjectSafetyViolation::Method( + name, + MethodViolationCode::ReferencesSelfInput(_), + DUMMY_SP, + ) => format!("method `{}` references the `Self` type in its parameters", name).into(), + ObjectSafetyViolation::Method(name, MethodViolationCode::ReferencesSelfInput(_), _) => { + format!("method `{}` references the `Self` type in this parameter", name).into() + } + ObjectSafetyViolation::Method(name, MethodViolationCode::ReferencesSelfOutput, _) => { + format!("method `{}` references the `Self` type in its return type", name).into() + } + ObjectSafetyViolation::Method( + name, + MethodViolationCode::WhereClauseReferencesSelf, + _, + ) => { + format!("method `{}` references the `Self` type in its `where` clause", name).into() + } + ObjectSafetyViolation::Method(name, MethodViolationCode::Generic, _) => { + format!("method `{}` has generic type parameters", name).into() + } + ObjectSafetyViolation::Method(name, MethodViolationCode::UndispatchableReceiver, _) => { + format!("method `{}`'s `self` parameter cannot be dispatched on", name).into() + } + ObjectSafetyViolation::AssocConst(name, DUMMY_SP) => { + format!("it contains associated `const` `{}`", name).into() + } + ObjectSafetyViolation::AssocConst(..) => "it contains this associated `const`".into(), + } + } + + pub fn solution(&self) -> Option<(String, Option<(String, Span)>)> { + Some(match *self { + ObjectSafetyViolation::SizedSelf(_) | ObjectSafetyViolation::SupertraitSelf(_) => { + return None; + } + ObjectSafetyViolation::Method(name, MethodViolationCode::StaticMethod(sugg), _) => ( + format!( + "consider turning `{}` into a method by giving it a `&self` argument or \ + constraining it so it does not apply to trait objects", + name + ), + sugg.map(|(sugg, sp)| (sugg.to_string(), sp)), + ), + ObjectSafetyViolation::Method( + name, + MethodViolationCode::UndispatchableReceiver, + span, + ) => ( + format!("consider changing method `{}`'s `self` parameter to be `&self`", name), + Some(("&Self".to_string(), span)), + ), + ObjectSafetyViolation::AssocConst(name, _) + | ObjectSafetyViolation::Method(name, ..) => { + (format!("consider moving `{}` to another trait", name), None) + } + }) + } + + pub fn spans(&self) -> SmallVec<[Span; 1]> { + // When `span` comes from a separate crate, it'll be `DUMMY_SP`. Treat it as `None` so + // diagnostics use a `note` instead of a `span_label`. + match self { + ObjectSafetyViolation::SupertraitSelf(spans) + | ObjectSafetyViolation::SizedSelf(spans) => spans.clone(), + ObjectSafetyViolation::AssocConst(_, span) + | ObjectSafetyViolation::Method(_, _, span) + if *span != DUMMY_SP => + { + smallvec![*span] + } + _ => smallvec![], + } + } +} + +/// Reasons a method might not be object-safe. +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)] +pub enum MethodViolationCode { + /// e.g., `fn foo()` + StaticMethod(Option<(&'static str, Span)>), + + /// e.g., `fn foo(&self, x: Self)` + ReferencesSelfInput(usize), + + /// e.g., `fn foo(&self) -> Self` + ReferencesSelfOutput, + + /// e.g., `fn foo(&self) where Self: Clone` + WhereClauseReferencesSelf, + + /// e.g., `fn foo<A>()` + Generic, + + /// the method's receiver (`self` argument) can't be dispatched on + UndispatchableReceiver, +} diff --git a/compiler/rustc_middle/src/traits/query.rs b/compiler/rustc_middle/src/traits/query.rs new file mode 100644 index 00000000000..4b7663e9ade --- /dev/null +++ b/compiler/rustc_middle/src/traits/query.rs @@ -0,0 +1,330 @@ +//! Experimental types for the trait query interface. The methods +//! defined in this module are all based on **canonicalization**, +//! which makes a canonical query by replacing unbound inference +//! variables and regions, so that results can be reused more broadly. +//! The providers for the queries defined here can be found in +//! `librustc_traits`. + +use crate::ich::StableHashingContext; +use crate::infer::canonical::{Canonical, QueryResponse}; +use crate::ty::error::TypeError; +use crate::ty::subst::GenericArg; +use crate::ty::{self, Ty, TyCtxt}; + +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_data_structures::sync::Lrc; +use rustc_errors::struct_span_err; +use rustc_span::source_map::Span; +use std::iter::FromIterator; +use std::mem; + +pub mod type_op { + use crate::ty::fold::TypeFoldable; + use crate::ty::subst::UserSubsts; + use crate::ty::{Predicate, Ty}; + use rustc_hir::def_id::DefId; + use std::fmt; + + #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)] + pub struct AscribeUserType<'tcx> { + pub mir_ty: Ty<'tcx>, + pub def_id: DefId, + pub user_substs: UserSubsts<'tcx>, + } + + impl<'tcx> AscribeUserType<'tcx> { + pub fn new(mir_ty: Ty<'tcx>, def_id: DefId, user_substs: UserSubsts<'tcx>) -> Self { + Self { mir_ty, def_id, user_substs } + } + } + + #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)] + pub struct Eq<'tcx> { + pub a: Ty<'tcx>, + pub b: Ty<'tcx>, + } + + impl<'tcx> Eq<'tcx> { + pub fn new(a: Ty<'tcx>, b: Ty<'tcx>) -> Self { + Self { a, b } + } + } + + #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)] + pub struct Subtype<'tcx> { + pub sub: Ty<'tcx>, + pub sup: Ty<'tcx>, + } + + impl<'tcx> Subtype<'tcx> { + pub fn new(sub: Ty<'tcx>, sup: Ty<'tcx>) -> Self { + Self { sub, sup } + } + } + + #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)] + pub struct ProvePredicate<'tcx> { + pub predicate: Predicate<'tcx>, + } + + impl<'tcx> ProvePredicate<'tcx> { + pub fn new(predicate: Predicate<'tcx>) -> Self { + ProvePredicate { predicate } + } + } + + #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)] + pub struct Normalize<T> { + pub value: T, + } + + impl<'tcx, T> Normalize<T> + where + T: fmt::Debug + TypeFoldable<'tcx>, + { + pub fn new(value: T) -> Self { + Self { value } + } + } +} + +pub type CanonicalProjectionGoal<'tcx> = + Canonical<'tcx, ty::ParamEnvAnd<'tcx, ty::ProjectionTy<'tcx>>>; + +pub type CanonicalTyGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, Ty<'tcx>>>; + +pub type CanonicalPredicateGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, ty::Predicate<'tcx>>>; + +pub type CanonicalTypeOpAscribeUserTypeGoal<'tcx> = + Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::AscribeUserType<'tcx>>>; + +pub type CanonicalTypeOpEqGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Eq<'tcx>>>; + +pub type CanonicalTypeOpSubtypeGoal<'tcx> = + Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Subtype<'tcx>>>; + +pub type CanonicalTypeOpProvePredicateGoal<'tcx> = + Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::ProvePredicate<'tcx>>>; + +pub type CanonicalTypeOpNormalizeGoal<'tcx, T> = + Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Normalize<T>>>; + +#[derive(Clone, Debug, HashStable)] +pub struct NoSolution; + +pub type Fallible<T> = Result<T, NoSolution>; + +impl<'tcx> From<TypeError<'tcx>> for NoSolution { + fn from(_: TypeError<'tcx>) -> NoSolution { + NoSolution + } +} + +#[derive(Clone, Debug, Default, HashStable, TypeFoldable, Lift)] +pub struct DropckOutlivesResult<'tcx> { + pub kinds: Vec<GenericArg<'tcx>>, + pub overflows: Vec<Ty<'tcx>>, +} + +impl<'tcx> DropckOutlivesResult<'tcx> { + pub fn report_overflows(&self, tcx: TyCtxt<'tcx>, span: Span, ty: Ty<'tcx>) { + if let Some(overflow_ty) = self.overflows.get(0) { + let mut err = struct_span_err!( + tcx.sess, + span, + E0320, + "overflow while adding drop-check rules for {}", + ty, + ); + err.note(&format!("overflowed on {}", overflow_ty)); + err.emit(); + } + } + + pub fn into_kinds_reporting_overflows( + self, + tcx: TyCtxt<'tcx>, + span: Span, + ty: Ty<'tcx>, + ) -> Vec<GenericArg<'tcx>> { + self.report_overflows(tcx, span, ty); + let DropckOutlivesResult { kinds, overflows: _ } = self; + kinds + } +} + +/// A set of constraints that need to be satisfied in order for +/// a type to be valid for destruction. +#[derive(Clone, Debug, HashStable)] +pub struct DtorckConstraint<'tcx> { + /// Types that are required to be alive in order for this + /// type to be valid for destruction. + pub outlives: Vec<ty::subst::GenericArg<'tcx>>, + + /// Types that could not be resolved: projections and params. + pub dtorck_types: Vec<Ty<'tcx>>, + + /// If, during the computation of the dtorck constraint, we + /// overflow, that gets recorded here. The caller is expected to + /// report an error. + pub overflows: Vec<Ty<'tcx>>, +} + +impl<'tcx> DtorckConstraint<'tcx> { + pub fn empty() -> DtorckConstraint<'tcx> { + DtorckConstraint { outlives: vec![], dtorck_types: vec![], overflows: vec![] } + } +} + +impl<'tcx> FromIterator<DtorckConstraint<'tcx>> for DtorckConstraint<'tcx> { + fn from_iter<I: IntoIterator<Item = DtorckConstraint<'tcx>>>(iter: I) -> Self { + let mut result = Self::empty(); + + for DtorckConstraint { outlives, dtorck_types, overflows } in iter { + result.outlives.extend(outlives); + result.dtorck_types.extend(dtorck_types); + result.overflows.extend(overflows); + } + + result + } +} + +/// This returns true if the type `ty` is "trivial" for +/// dropck-outlives -- that is, if it doesn't require any types to +/// outlive. This is similar but not *quite* the same as the +/// `needs_drop` test in the compiler already -- that is, for every +/// type T for which this function return true, needs-drop would +/// return `false`. But the reverse does not hold: in particular, +/// `needs_drop` returns false for `PhantomData`, but it is not +/// trivial for dropck-outlives. +/// +/// Note also that `needs_drop` requires a "global" type (i.e., one +/// with erased regions), but this function does not. +pub fn trivial_dropck_outlives<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool { + match ty.kind { + // None of these types have a destructor and hence they do not + // require anything in particular to outlive the dtor's + // execution. + ty::Infer(ty::FreshIntTy(_)) + | ty::Infer(ty::FreshFloatTy(_)) + | ty::Bool + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Never + | ty::FnDef(..) + | ty::FnPtr(_) + | ty::Char + | ty::GeneratorWitness(..) + | ty::RawPtr(_) + | ty::Ref(..) + | ty::Str + | ty::Foreign(..) + | ty::Error(_) => true, + + // [T; N] and [T] have same properties as T. + ty::Array(ty, _) | ty::Slice(ty) => trivial_dropck_outlives(tcx, ty), + + // (T1..Tn) and closures have same properties as T1..Tn -- + // check if *any* of those are trivial. + ty::Tuple(ref tys) => tys.iter().all(|t| trivial_dropck_outlives(tcx, t.expect_ty())), + ty::Closure(_, ref substs) => { + substs.as_closure().upvar_tys().all(|t| trivial_dropck_outlives(tcx, t)) + } + + ty::Adt(def, _) => { + if Some(def.did) == tcx.lang_items().manually_drop() { + // `ManuallyDrop` never has a dtor. + true + } else { + // Other types might. Moreover, PhantomData doesn't + // have a dtor, but it is considered to own its + // content, so it is non-trivial. Unions can have `impl Drop`, + // and hence are non-trivial as well. + false + } + } + + // The following *might* require a destructor: needs deeper inspection. + ty::Dynamic(..) + | ty::Projection(..) + | ty::Param(_) + | ty::Opaque(..) + | ty::Placeholder(..) + | ty::Infer(_) + | ty::Bound(..) + | ty::Generator(..) => false, + } +} + +#[derive(Debug, HashStable)] +pub struct CandidateStep<'tcx> { + pub self_ty: Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, + pub autoderefs: usize, + /// `true` if the type results from a dereference of a raw pointer. + /// when assembling candidates, we include these steps, but not when + /// picking methods. This so that if we have `foo: *const Foo` and `Foo` has methods + /// `fn by_raw_ptr(self: *const Self)` and `fn by_ref(&self)`, then + /// `foo.by_raw_ptr()` will work and `foo.by_ref()` won't. + pub from_unsafe_deref: bool, + pub unsize: bool, +} + +#[derive(Clone, Debug, HashStable)] +pub struct MethodAutoderefStepsResult<'tcx> { + /// The valid autoderef steps that could be find. + pub steps: Lrc<Vec<CandidateStep<'tcx>>>, + /// If Some(T), a type autoderef reported an error on. + pub opt_bad_ty: Option<Lrc<MethodAutoderefBadTy<'tcx>>>, + /// If `true`, `steps` has been truncated due to reaching the + /// recursion limit. + pub reached_recursion_limit: bool, +} + +#[derive(Debug, HashStable)] +pub struct MethodAutoderefBadTy<'tcx> { + pub reached_raw_pointer: bool, + pub ty: Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, +} + +/// Result from the `normalize_projection_ty` query. +#[derive(Clone, Debug, HashStable, TypeFoldable, Lift)] +pub struct NormalizationResult<'tcx> { + /// Result of normalization. + pub normalized_ty: Ty<'tcx>, +} + +/// Outlives bounds are relationships between generic parameters, +/// whether they both be regions (`'a: 'b`) or whether types are +/// involved (`T: 'a`). These relationships can be extracted from the +/// full set of predicates we understand or also from types (in which +/// case they are called implied bounds). They are fed to the +/// `OutlivesEnv` which in turn is supplied to the region checker and +/// other parts of the inference system. +#[derive(Clone, Debug, TypeFoldable, Lift)] +pub enum OutlivesBound<'tcx> { + RegionSubRegion(ty::Region<'tcx>, ty::Region<'tcx>), + RegionSubParam(ty::Region<'tcx>, ty::ParamTy), + RegionSubProjection(ty::Region<'tcx>, ty::ProjectionTy<'tcx>), +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for OutlivesBound<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + mem::discriminant(self).hash_stable(hcx, hasher); + match *self { + OutlivesBound::RegionSubRegion(ref a, ref b) => { + a.hash_stable(hcx, hasher); + b.hash_stable(hcx, hasher); + } + OutlivesBound::RegionSubParam(ref a, ref b) => { + a.hash_stable(hcx, hasher); + b.hash_stable(hcx, hasher); + } + OutlivesBound::RegionSubProjection(ref a, ref b) => { + a.hash_stable(hcx, hasher); + b.hash_stable(hcx, hasher); + } + } + } +} diff --git a/compiler/rustc_middle/src/traits/select.rs b/compiler/rustc_middle/src/traits/select.rs new file mode 100644 index 00000000000..6ad514c6be2 --- /dev/null +++ b/compiler/rustc_middle/src/traits/select.rs @@ -0,0 +1,255 @@ +//! Candidate selection. See the [rustc dev guide] for more information on how this works. +//! +//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/resolution.html#selection + +use self::EvaluationResult::*; + +use super::{SelectionError, SelectionResult}; + +use crate::ty; + +use rustc_hir::def_id::DefId; +use rustc_query_system::cache::Cache; + +pub type SelectionCache<'tcx> = Cache< + ty::ParamEnvAnd<'tcx, ty::TraitRef<'tcx>>, + SelectionResult<'tcx, SelectionCandidate<'tcx>>, +>; + +pub type EvaluationCache<'tcx> = + Cache<ty::ParamEnvAnd<'tcx, ty::PolyTraitRef<'tcx>>, EvaluationResult>; + +/// The selection process begins by considering all impls, where +/// clauses, and so forth that might resolve an obligation. Sometimes +/// we'll be able to say definitively that (e.g.) an impl does not +/// apply to the obligation: perhaps it is defined for `usize` but the +/// obligation is for `i32`. In that case, we drop the impl out of the +/// list. But the other cases are considered *candidates*. +/// +/// For selection to succeed, there must be exactly one matching +/// candidate. If the obligation is fully known, this is guaranteed +/// by coherence. However, if the obligation contains type parameters +/// or variables, there may be multiple such impls. +/// +/// It is not a real problem if multiple matching impls exist because +/// of type variables - it just means the obligation isn't sufficiently +/// elaborated. In that case we report an ambiguity, and the caller can +/// try again after more type information has been gathered or report a +/// "type annotations needed" error. +/// +/// However, with type parameters, this can be a real problem - type +/// parameters don't unify with regular types, but they *can* unify +/// with variables from blanket impls, and (unless we know its bounds +/// will always be satisfied) picking the blanket impl will be wrong +/// for at least *some* substitutions. To make this concrete, if we have +/// +/// ```rust, ignore +/// trait AsDebug { type Out: fmt::Debug; fn debug(self) -> Self::Out; } +/// impl<T: fmt::Debug> AsDebug for T { +/// type Out = T; +/// fn debug(self) -> fmt::Debug { self } +/// } +/// fn foo<T: AsDebug>(t: T) { println!("{:?}", <T as AsDebug>::debug(t)); } +/// ``` +/// +/// we can't just use the impl to resolve the `<T as AsDebug>` obligation +/// -- a type from another crate (that doesn't implement `fmt::Debug`) could +/// implement `AsDebug`. +/// +/// Because where-clauses match the type exactly, multiple clauses can +/// only match if there are unresolved variables, and we can mostly just +/// report this ambiguity in that case. This is still a problem - we can't +/// *do anything* with ambiguities that involve only regions. This is issue +/// #21974. +/// +/// If a single where-clause matches and there are no inference +/// variables left, then it definitely matches and we can just select +/// it. +/// +/// In fact, we even select the where-clause when the obligation contains +/// inference variables. The can lead to inference making "leaps of logic", +/// for example in this situation: +/// +/// ```rust, ignore +/// pub trait Foo<T> { fn foo(&self) -> T; } +/// impl<T> Foo<()> for T { fn foo(&self) { } } +/// impl Foo<bool> for bool { fn foo(&self) -> bool { *self } } +/// +/// pub fn foo<T>(t: T) where T: Foo<bool> { +/// println!("{:?}", <T as Foo<_>>::foo(&t)); +/// } +/// fn main() { foo(false); } +/// ``` +/// +/// Here the obligation `<T as Foo<$0>>` can be matched by both the blanket +/// impl and the where-clause. We select the where-clause and unify `$0=bool`, +/// so the program prints "false". However, if the where-clause is omitted, +/// the blanket impl is selected, we unify `$0=()`, and the program prints +/// "()". +/// +/// Exactly the same issues apply to projection and object candidates, except +/// that we can have both a projection candidate and a where-clause candidate +/// for the same obligation. In that case either would do (except that +/// different "leaps of logic" would occur if inference variables are +/// present), and we just pick the where-clause. This is, for example, +/// required for associated types to work in default impls, as the bounds +/// are visible both as projection bounds and as where-clauses from the +/// parameter environment. +#[derive(PartialEq, Eq, Debug, Clone, TypeFoldable)] +pub enum SelectionCandidate<'tcx> { + BuiltinCandidate { + /// `false` if there are no *further* obligations. + has_nested: bool, + }, + ParamCandidate(ty::PolyTraitRef<'tcx>), + ImplCandidate(DefId), + AutoImplCandidate(DefId), + + /// This is a trait matching with a projected type as `Self`, and + /// we found an applicable bound in the trait definition. + ProjectionCandidate, + + /// Implementation of a `Fn`-family trait by one of the anonymous types + /// generated for a `||` expression. + ClosureCandidate, + + /// Implementation of a `Generator` trait by one of the anonymous types + /// generated for a generator. + GeneratorCandidate, + + /// Implementation of a `Fn`-family trait by one of the anonymous + /// types generated for a fn pointer type (e.g., `fn(int) -> int`) + FnPointerCandidate, + + /// Builtin implementation of `DiscriminantKind`. + DiscriminantKindCandidate, + + TraitAliasCandidate(DefId), + + ObjectCandidate, + + BuiltinObjectCandidate, + + BuiltinUnsizeCandidate, +} + +/// The result of trait evaluation. The order is important +/// here as the evaluation of a list is the maximum of the +/// evaluations. +/// +/// The evaluation results are ordered: +/// - `EvaluatedToOk` implies `EvaluatedToOkModuloRegions` +/// implies `EvaluatedToAmbig` implies `EvaluatedToUnknown` +/// - `EvaluatedToErr` implies `EvaluatedToRecur` +/// - the "union" of evaluation results is equal to their maximum - +/// all the "potential success" candidates can potentially succeed, +/// so they are noops when unioned with a definite error, and within +/// the categories it's easy to see that the unions are correct. +#[derive(Copy, Clone, Debug, PartialOrd, Ord, PartialEq, Eq, HashStable)] +pub enum EvaluationResult { + /// Evaluation successful. + EvaluatedToOk, + /// Evaluation successful, but there were unevaluated region obligations. + EvaluatedToOkModuloRegions, + /// Evaluation is known to be ambiguous -- it *might* hold for some + /// assignment of inference variables, but it might not. + /// + /// While this has the same meaning as `EvaluatedToUnknown` -- we can't + /// know whether this obligation holds or not -- it is the result we + /// would get with an empty stack, and therefore is cacheable. + EvaluatedToAmbig, + /// Evaluation failed because of recursion involving inference + /// variables. We are somewhat imprecise there, so we don't actually + /// know the real result. + /// + /// This can't be trivially cached for the same reason as `EvaluatedToRecur`. + EvaluatedToUnknown, + /// Evaluation failed because we encountered an obligation we are already + /// trying to prove on this branch. + /// + /// We know this branch can't be a part of a minimal proof-tree for + /// the "root" of our cycle, because then we could cut out the recursion + /// and maintain a valid proof tree. However, this does not mean + /// that all the obligations on this branch do not hold -- it's possible + /// that we entered this branch "speculatively", and that there + /// might be some other way to prove this obligation that does not + /// go through this cycle -- so we can't cache this as a failure. + /// + /// For example, suppose we have this: + /// + /// ```rust,ignore (pseudo-Rust) + /// pub trait Trait { fn xyz(); } + /// // This impl is "useless", but we can still have + /// // an `impl Trait for SomeUnsizedType` somewhere. + /// impl<T: Trait + Sized> Trait for T { fn xyz() {} } + /// + /// pub fn foo<T: Trait + ?Sized>() { + /// <T as Trait>::xyz(); + /// } + /// ``` + /// + /// When checking `foo`, we have to prove `T: Trait`. This basically + /// translates into this: + /// + /// ```plain,ignore + /// (T: Trait + Sized →_\impl T: Trait), T: Trait ⊢ T: Trait + /// ``` + /// + /// When we try to prove it, we first go the first option, which + /// recurses. This shows us that the impl is "useless" -- it won't + /// tell us that `T: Trait` unless it already implemented `Trait` + /// by some other means. However, that does not prevent `T: Trait` + /// does not hold, because of the bound (which can indeed be satisfied + /// by `SomeUnsizedType` from another crate). + // + // FIXME: when an `EvaluatedToRecur` goes past its parent root, we + // ought to convert it to an `EvaluatedToErr`, because we know + // there definitely isn't a proof tree for that obligation. Not + // doing so is still sound -- there isn't any proof tree, so the + // branch still can't be a part of a minimal one -- but does not re-enable caching. + EvaluatedToRecur, + /// Evaluation failed. + EvaluatedToErr, +} + +impl EvaluationResult { + /// Returns `true` if this evaluation result is known to apply, even + /// considering outlives constraints. + pub fn must_apply_considering_regions(self) -> bool { + self == EvaluatedToOk + } + + /// Returns `true` if this evaluation result is known to apply, ignoring + /// outlives constraints. + pub fn must_apply_modulo_regions(self) -> bool { + self <= EvaluatedToOkModuloRegions + } + + pub fn may_apply(self) -> bool { + match self { + EvaluatedToOk | EvaluatedToOkModuloRegions | EvaluatedToAmbig | EvaluatedToUnknown => { + true + } + + EvaluatedToErr | EvaluatedToRecur => false, + } + } + + pub fn is_stack_dependent(self) -> bool { + match self { + EvaluatedToUnknown | EvaluatedToRecur => true, + + EvaluatedToOk | EvaluatedToOkModuloRegions | EvaluatedToAmbig | EvaluatedToErr => false, + } + } +} + +/// Indicates that trait evaluation caused overflow. +#[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable)] +pub struct OverflowError; + +impl<'tcx> From<OverflowError> for SelectionError<'tcx> { + fn from(OverflowError: OverflowError) -> SelectionError<'tcx> { + SelectionError::Overflow + } +} diff --git a/compiler/rustc_middle/src/traits/specialization_graph.rs b/compiler/rustc_middle/src/traits/specialization_graph.rs new file mode 100644 index 00000000000..969404c68ca --- /dev/null +++ b/compiler/rustc_middle/src/traits/specialization_graph.rs @@ -0,0 +1,248 @@ +use crate::ich::{self, StableHashingContext}; +use crate::ty::fast_reject::SimplifiedType; +use crate::ty::fold::TypeFoldable; +use crate::ty::{self, TyCtxt}; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_errors::ErrorReported; +use rustc_hir::def_id::{DefId, DefIdMap}; +use rustc_span::symbol::Ident; + +/// A per-trait graph of impls in specialization order. At the moment, this +/// graph forms a tree rooted with the trait itself, with all other nodes +/// representing impls, and parent-child relationships representing +/// specializations. +/// +/// The graph provides two key services: +/// +/// - Construction. This implicitly checks for overlapping impls (i.e., impls +/// that overlap but where neither specializes the other -- an artifact of the +/// simple "chain" rule. +/// +/// - Parent extraction. In particular, the graph can give you the *immediate* +/// parents of a given specializing impl, which is needed for extracting +/// default items amongst other things. In the simple "chain" rule, every impl +/// has at most one parent. +#[derive(TyEncodable, TyDecodable, HashStable)] +pub struct Graph { + /// All impls have a parent; the "root" impls have as their parent the `def_id` + /// of the trait. + pub parent: DefIdMap<DefId>, + + /// The "root" impls are found by looking up the trait's def_id. + pub children: DefIdMap<Children>, + + /// Whether an error was emitted while constructing the graph. + pub has_errored: bool, +} + +impl Graph { + pub fn new() -> Graph { + Graph { parent: Default::default(), children: Default::default(), has_errored: false } + } + + /// The parent of a given impl, which is the `DefId` of the trait when the + /// impl is a "specialization root". + pub fn parent(&self, child: DefId) -> DefId { + *self.parent.get(&child).unwrap_or_else(|| panic!("Failed to get parent for {:?}", child)) + } +} + +/// Children of a given impl, grouped into blanket/non-blanket varieties as is +/// done in `TraitDef`. +#[derive(Default, TyEncodable, TyDecodable)] +pub struct Children { + // Impls of a trait (or specializations of a given impl). To allow for + // quicker lookup, the impls are indexed by a simplified version of their + // `Self` type: impls with a simplifiable `Self` are stored in + // `nonblanket_impls` keyed by it, while all other impls are stored in + // `blanket_impls`. + // + // A similar division is used within `TraitDef`, but the lists there collect + // together *all* the impls for a trait, and are populated prior to building + // the specialization graph. + /// Impls of the trait. + pub nonblanket_impls: FxHashMap<SimplifiedType, Vec<DefId>>, + + /// Blanket impls associated with the trait. + pub blanket_impls: Vec<DefId>, +} + +/// A node in the specialization graph is either an impl or a trait +/// definition; either can serve as a source of item definitions. +/// There is always exactly one trait definition node: the root. +#[derive(Debug, Copy, Clone)] +pub enum Node { + Impl(DefId), + Trait(DefId), +} + +impl<'tcx> Node { + pub fn is_from_trait(&self) -> bool { + match *self { + Node::Trait(..) => true, + _ => false, + } + } + + /// Iterate over the items defined directly by the given (impl or trait) node. + pub fn items(&self, tcx: TyCtxt<'tcx>) -> impl 'tcx + Iterator<Item = &'tcx ty::AssocItem> { + tcx.associated_items(self.def_id()).in_definition_order() + } + + /// Finds an associated item defined in this node. + /// + /// If this returns `None`, the item can potentially still be found in + /// parents of this node. + pub fn item( + &self, + tcx: TyCtxt<'tcx>, + trait_item_name: Ident, + trait_item_kind: ty::AssocKind, + trait_def_id: DefId, + ) -> Option<ty::AssocItem> { + tcx.associated_items(self.def_id()) + .filter_by_name_unhygienic(trait_item_name.name) + .find(move |impl_item| { + trait_item_kind == impl_item.kind + && tcx.hygienic_eq(impl_item.ident, trait_item_name, trait_def_id) + }) + .copied() + } + + pub fn def_id(&self) -> DefId { + match *self { + Node::Impl(did) => did, + Node::Trait(did) => did, + } + } +} + +#[derive(Copy, Clone)] +pub struct Ancestors<'tcx> { + trait_def_id: DefId, + specialization_graph: &'tcx Graph, + current_source: Option<Node>, +} + +impl Iterator for Ancestors<'_> { + type Item = Node; + fn next(&mut self) -> Option<Node> { + let cur = self.current_source.take(); + if let Some(Node::Impl(cur_impl)) = cur { + let parent = self.specialization_graph.parent(cur_impl); + + self.current_source = if parent == self.trait_def_id { + Some(Node::Trait(parent)) + } else { + Some(Node::Impl(parent)) + }; + } + cur + } +} + +/// Information about the most specialized definition of an associated item. +pub struct LeafDef { + /// The associated item described by this `LeafDef`. + pub item: ty::AssocItem, + + /// The node in the specialization graph containing the definition of `item`. + pub defining_node: Node, + + /// The "top-most" (ie. least specialized) specialization graph node that finalized the + /// definition of `item`. + /// + /// Example: + /// + /// ``` + /// trait Tr { + /// fn assoc(&self); + /// } + /// + /// impl<T> Tr for T { + /// default fn assoc(&self) {} + /// } + /// + /// impl Tr for u8 {} + /// ``` + /// + /// If we start the leaf definition search at `impl Tr for u8`, that impl will be the + /// `finalizing_node`, while `defining_node` will be the generic impl. + /// + /// If the leaf definition search is started at the generic impl, `finalizing_node` will be + /// `None`, since the most specialized impl we found still allows overriding the method + /// (doesn't finalize it). + pub finalizing_node: Option<Node>, +} + +impl LeafDef { + /// Returns whether this definition is known to not be further specializable. + pub fn is_final(&self) -> bool { + self.finalizing_node.is_some() + } +} + +impl<'tcx> Ancestors<'tcx> { + /// Finds the bottom-most (ie. most specialized) definition of an associated + /// item. + pub fn leaf_def( + mut self, + tcx: TyCtxt<'tcx>, + trait_item_name: Ident, + trait_item_kind: ty::AssocKind, + ) -> Option<LeafDef> { + let trait_def_id = self.trait_def_id; + let mut finalizing_node = None; + + self.find_map(|node| { + if let Some(item) = node.item(tcx, trait_item_name, trait_item_kind, trait_def_id) { + if finalizing_node.is_none() { + let is_specializable = item.defaultness.is_default() + || tcx.impl_defaultness(node.def_id()).is_default(); + + if !is_specializable { + finalizing_node = Some(node); + } + } + + Some(LeafDef { item, defining_node: node, finalizing_node }) + } else { + // Item not mentioned. This "finalizes" any defaulted item provided by an ancestor. + finalizing_node = Some(node); + None + } + }) + } +} + +/// Walk up the specialization ancestors of a given impl, starting with that +/// impl itself. +/// +/// Returns `Err` if an error was reported while building the specialization +/// graph. +pub fn ancestors( + tcx: TyCtxt<'tcx>, + trait_def_id: DefId, + start_from_impl: DefId, +) -> Result<Ancestors<'tcx>, ErrorReported> { + let specialization_graph = tcx.specialization_graph_of(trait_def_id); + + if specialization_graph.has_errored || tcx.type_of(start_from_impl).references_error() { + Err(ErrorReported) + } else { + Ok(Ancestors { + trait_def_id, + specialization_graph, + current_source: Some(Node::Impl(start_from_impl)), + }) + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for Children { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let Children { ref nonblanket_impls, ref blanket_impls } = *self; + + ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, nonblanket_impls); + } +} diff --git a/compiler/rustc_middle/src/traits/structural_impls.rs b/compiler/rustc_middle/src/traits/structural_impls.rs new file mode 100644 index 00000000000..d73fc628ceb --- /dev/null +++ b/compiler/rustc_middle/src/traits/structural_impls.rs @@ -0,0 +1,111 @@ +use crate::traits; + +use std::fmt; + +// Structural impls for the structs in `traits`. + +impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSource<'tcx, N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + super::ImplSourceUserDefined(ref v) => write!(f, "{:?}", v), + + super::ImplSourceAutoImpl(ref t) => write!(f, "{:?}", t), + + super::ImplSourceClosure(ref d) => write!(f, "{:?}", d), + + super::ImplSourceGenerator(ref d) => write!(f, "{:?}", d), + + super::ImplSourceFnPointer(ref d) => write!(f, "ImplSourceFnPointer({:?})", d), + + super::ImplSourceDiscriminantKind(ref d) => write!(f, "{:?}", d), + + super::ImplSourceObject(ref d) => write!(f, "{:?}", d), + + super::ImplSourceParam(ref n) => write!(f, "ImplSourceParam({:?})", n), + + super::ImplSourceBuiltin(ref d) => write!(f, "{:?}", d), + + super::ImplSourceTraitAlias(ref d) => write!(f, "{:?}", d), + } + } +} + +impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceUserDefinedData<'tcx, N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "ImplSourceUserDefinedData(impl_def_id={:?}, substs={:?}, nested={:?})", + self.impl_def_id, self.substs, self.nested + ) + } +} + +impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceGeneratorData<'tcx, N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "ImplSourceGeneratorData(generator_def_id={:?}, substs={:?}, nested={:?})", + self.generator_def_id, self.substs, self.nested + ) + } +} + +impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceClosureData<'tcx, N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "ImplSourceClosureData(closure_def_id={:?}, substs={:?}, nested={:?})", + self.closure_def_id, self.substs, self.nested + ) + } +} + +impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceBuiltinData<N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "ImplSourceBuiltinData(nested={:?})", self.nested) + } +} + +impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceAutoImplData<N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "ImplSourceAutoImplData(trait_def_id={:?}, nested={:?})", + self.trait_def_id, self.nested + ) + } +} + +impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceObjectData<'tcx, N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "ImplSourceObjectData(upcast={:?}, vtable_base={}, nested={:?})", + self.upcast_trait_ref, self.vtable_base, self.nested + ) + } +} + +impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceFnPointerData<'tcx, N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "ImplSourceFnPointerData(fn_ty={:?}, nested={:?})", self.fn_ty, self.nested) + } +} + +impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceTraitAliasData<'tcx, N> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "ImplSourceTraitAlias(alias_def_id={:?}, substs={:?}, nested={:?})", + self.alias_def_id, self.substs, self.nested + ) + } +} + +/////////////////////////////////////////////////////////////////////////// +// Lift implementations + +CloneTypeFoldableAndLiftImpls! { + super::IfExpressionCause, + super::ImplSourceDiscriminantKindData, +} diff --git a/compiler/rustc_middle/src/ty/_match.rs b/compiler/rustc_middle/src/ty/_match.rs new file mode 100644 index 00000000000..4693a2f66fb --- /dev/null +++ b/compiler/rustc_middle/src/ty/_match.rs @@ -0,0 +1,123 @@ +use crate::ty::error::TypeError; +use crate::ty::relate::{self, Relate, RelateResult, TypeRelation}; +use crate::ty::{self, InferConst, Ty, TyCtxt}; + +/// A type "A" *matches* "B" if the fresh types in B could be +/// substituted with values so as to make it equal to A. Matching is +/// intended to be used only on freshened types, and it basically +/// indicates if the non-freshened versions of A and B could have been +/// unified. +/// +/// It is only an approximation. If it yields false, unification would +/// definitely fail, but a true result doesn't mean unification would +/// succeed. This is because we don't track the "side-constraints" on +/// type variables, nor do we track if the same freshened type appears +/// more than once. To some extent these approximations could be +/// fixed, given effort. +/// +/// Like subtyping, matching is really a binary relation, so the only +/// important thing about the result is Ok/Err. Also, matching never +/// affects any type variables or unification state. +pub struct Match<'tcx> { + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, +} + +impl Match<'tcx> { + pub fn new(tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Match<'tcx> { + Match { tcx, param_env } + } +} + +impl TypeRelation<'tcx> for Match<'tcx> { + fn tag(&self) -> &'static str { + "Match" + } + fn tcx(&self) -> TyCtxt<'tcx> { + self.tcx + } + fn param_env(&self) -> ty::ParamEnv<'tcx> { + self.param_env + } + fn a_is_expected(&self) -> bool { + true + } // irrelevant + + fn relate_with_variance<T: Relate<'tcx>>( + &mut self, + _: ty::Variance, + a: T, + b: T, + ) -> RelateResult<'tcx, T> { + self.relate(a, b) + } + + fn regions( + &mut self, + a: ty::Region<'tcx>, + b: ty::Region<'tcx>, + ) -> RelateResult<'tcx, ty::Region<'tcx>> { + debug!("{}.regions({:?}, {:?})", self.tag(), a, b); + Ok(a) + } + + fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> { + debug!("{}.tys({:?}, {:?})", self.tag(), a, b); + if a == b { + return Ok(a); + } + + match (&a.kind, &b.kind) { + ( + _, + &ty::Infer(ty::FreshTy(_)) + | &ty::Infer(ty::FreshIntTy(_)) + | &ty::Infer(ty::FreshFloatTy(_)), + ) => Ok(a), + + (&ty::Infer(_), _) | (_, &ty::Infer(_)) => { + Err(TypeError::Sorts(relate::expected_found(self, &a, &b))) + } + + (&ty::Error(_), _) | (_, &ty::Error(_)) => Ok(self.tcx().ty_error()), + + _ => relate::super_relate_tys(self, a, b), + } + } + + fn consts( + &mut self, + a: &'tcx ty::Const<'tcx>, + b: &'tcx ty::Const<'tcx>, + ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> { + debug!("{}.consts({:?}, {:?})", self.tag(), a, b); + if a == b { + return Ok(a); + } + + match (a.val, b.val) { + (_, ty::ConstKind::Infer(InferConst::Fresh(_))) => { + return Ok(a); + } + + (ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => { + return Err(TypeError::ConstMismatch(relate::expected_found(self, &a, &b))); + } + + _ => {} + } + + relate::super_relate_consts(self, a, b) + } + + fn binders<T>( + &mut self, + a: ty::Binder<T>, + b: ty::Binder<T>, + ) -> RelateResult<'tcx, ty::Binder<T>> + where + T: Relate<'tcx>, + { + Ok(ty::Binder::bind(self.relate(a.skip_binder(), b.skip_binder())?)) + } +} diff --git a/compiler/rustc_middle/src/ty/adjustment.rs b/compiler/rustc_middle/src/ty/adjustment.rs new file mode 100644 index 00000000000..6a9bb8d6c28 --- /dev/null +++ b/compiler/rustc_middle/src/ty/adjustment.rs @@ -0,0 +1,195 @@ +use crate::ty::subst::SubstsRef; +use crate::ty::{self, Ty, TyCtxt}; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_hir::lang_items::LangItem; +use rustc_macros::HashStable; + +#[derive(Clone, Copy, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] +pub enum PointerCast { + /// Go from a fn-item type to a fn-pointer type. + ReifyFnPointer, + + /// Go from a safe fn pointer to an unsafe fn pointer. + UnsafeFnPointer, + + /// Go from a non-capturing closure to an fn pointer or an unsafe fn pointer. + /// It cannot convert a closure that requires unsafe. + ClosureFnPointer(hir::Unsafety), + + /// Go from a mut raw pointer to a const raw pointer. + MutToConstPointer, + + /// Go from `*const [T; N]` to `*const T` + ArrayToPointer, + + /// Unsize a pointer/reference value, e.g., `&[T; n]` to + /// `&[T]`. Note that the source could be a thin or fat pointer. + /// This will do things like convert thin pointers to fat + /// pointers, or convert structs containing thin pointers to + /// structs containing fat pointers, or convert between fat + /// pointers. We don't store the details of how the transform is + /// done (in fact, we don't know that, because it might depend on + /// the precise type parameters). We just store the target + /// type. Codegen backends and miri figure out what has to be done + /// based on the precise source/target type at hand. + Unsize, +} + +/// Represents coercing a value to a different type of value. +/// +/// We transform values by following a number of `Adjust` steps in order. +/// See the documentation on variants of `Adjust` for more details. +/// +/// Here are some common scenarios: +/// +/// 1. The simplest cases are where a pointer is not adjusted fat vs thin. +/// Here the pointer will be dereferenced N times (where a dereference can +/// happen to raw or borrowed pointers or any smart pointer which implements +/// Deref, including Box<_>). The types of dereferences is given by +/// `autoderefs`. It can then be auto-referenced zero or one times, indicated +/// by `autoref`, to either a raw or borrowed pointer. In these cases unsize is +/// `false`. +/// +/// 2. A thin-to-fat coercion involves unsizing the underlying data. We start +/// with a thin pointer, deref a number of times, unsize the underlying data, +/// then autoref. The 'unsize' phase may change a fixed length array to a +/// dynamically sized one, a concrete object to a trait object, or statically +/// sized struct to a dynamically sized one. E.g., &[i32; 4] -> &[i32] is +/// represented by: +/// +/// ``` +/// Deref(None) -> [i32; 4], +/// Borrow(AutoBorrow::Ref) -> &[i32; 4], +/// Unsize -> &[i32], +/// ``` +/// +/// Note that for a struct, the 'deep' unsizing of the struct is not recorded. +/// E.g., `struct Foo<T> { x: T }` we can coerce &Foo<[i32; 4]> to &Foo<[i32]> +/// The autoderef and -ref are the same as in the above example, but the type +/// stored in `unsize` is `Foo<[i32]>`, we don't store any further detail about +/// the underlying conversions from `[i32; 4]` to `[i32]`. +/// +/// 3. Coercing a `Box<T>` to `Box<dyn Trait>` is an interesting special case. In +/// that case, we have the pointer we need coming in, so there are no +/// autoderefs, and no autoref. Instead we just do the `Unsize` transformation. +/// At some point, of course, `Box` should move out of the compiler, in which +/// case this is analogous to transforming a struct. E.g., Box<[i32; 4]> -> +/// Box<[i32]> is an `Adjust::Unsize` with the target `Box<[i32]>`. +#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct Adjustment<'tcx> { + pub kind: Adjust<'tcx>, + pub target: Ty<'tcx>, +} + +impl Adjustment<'tcx> { + pub fn is_region_borrow(&self) -> bool { + match self.kind { + Adjust::Borrow(AutoBorrow::Ref(..)) => true, + _ => false, + } + } +} + +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub enum Adjust<'tcx> { + /// Go from ! to any type. + NeverToAny, + + /// Dereference once, producing a place. + Deref(Option<OverloadedDeref<'tcx>>), + + /// Take the address and produce either a `&` or `*` pointer. + Borrow(AutoBorrow<'tcx>), + + Pointer(PointerCast), +} + +/// An overloaded autoderef step, representing a `Deref(Mut)::deref(_mut)` +/// call, with the signature `&'a T -> &'a U` or `&'a mut T -> &'a mut U`. +/// The target type is `U` in both cases, with the region and mutability +/// being those shared by both the receiver and the returned reference. +#[derive(Copy, Clone, PartialEq, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub struct OverloadedDeref<'tcx> { + pub region: ty::Region<'tcx>, + pub mutbl: hir::Mutability, +} + +impl<'tcx> OverloadedDeref<'tcx> { + pub fn method_call(&self, tcx: TyCtxt<'tcx>, source: Ty<'tcx>) -> (DefId, SubstsRef<'tcx>) { + let trait_def_id = match self.mutbl { + hir::Mutability::Not => tcx.require_lang_item(LangItem::Deref, None), + hir::Mutability::Mut => tcx.require_lang_item(LangItem::DerefMut, None), + }; + let method_def_id = tcx + .associated_items(trait_def_id) + .in_definition_order() + .find(|m| m.kind == ty::AssocKind::Fn) + .unwrap() + .def_id; + (method_def_id, tcx.mk_substs_trait(source, &[])) + } +} + +/// At least for initial deployment, we want to limit two-phase borrows to +/// only a few specific cases. Right now, those are mostly "things that desugar" +/// into method calls: +/// - using `x.some_method()` syntax, where some_method takes `&mut self`, +/// - using `Foo::some_method(&mut x, ...)` syntax, +/// - binary assignment operators (`+=`, `-=`, `*=`, etc.). +/// Anything else should be rejected until generalized two-phase borrow support +/// is implemented. Right now, dataflow can't handle the general case where there +/// is more than one use of a mutable borrow, and we don't want to accept too much +/// new code via two-phase borrows, so we try to limit where we create two-phase +/// capable mutable borrows. +/// See #49434 for tracking. +#[derive(Copy, Clone, PartialEq, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum AllowTwoPhase { + Yes, + No, +} + +#[derive(Copy, Clone, PartialEq, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum AutoBorrowMutability { + Mut { allow_two_phase_borrow: AllowTwoPhase }, + Not, +} + +impl From<AutoBorrowMutability> for hir::Mutability { + fn from(m: AutoBorrowMutability) -> Self { + match m { + AutoBorrowMutability::Mut { .. } => hir::Mutability::Mut, + AutoBorrowMutability::Not => hir::Mutability::Not, + } + } +} + +#[derive(Copy, Clone, PartialEq, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable)] +pub enum AutoBorrow<'tcx> { + /// Converts from T to &T. + Ref(ty::Region<'tcx>, AutoBorrowMutability), + + /// Converts from T to *T. + RawPtr(hir::Mutability), +} + +/// Information for `CoerceUnsized` impls, storing information we +/// have computed about the coercion. +/// +/// This struct can be obtained via the `coerce_impl_info` query. +/// Demanding this struct also has the side-effect of reporting errors +/// for inappropriate impls. +#[derive(Clone, Copy, TyEncodable, TyDecodable, Debug, HashStable)] +pub struct CoerceUnsizedInfo { + /// If this is a "custom coerce" impl, then what kind of custom + /// coercion is it? This applies to impls of `CoerceUnsized` for + /// structs, primarily, where we store a bit of info about which + /// fields need to be coerced. + pub custom_kind: Option<CustomCoerceUnsized>, +} + +#[derive(Clone, Copy, TyEncodable, TyDecodable, Debug, HashStable)] +pub enum CustomCoerceUnsized { + /// Records the index of the field being coerced. + Struct(usize), +} diff --git a/compiler/rustc_middle/src/ty/binding.rs b/compiler/rustc_middle/src/ty/binding.rs new file mode 100644 index 00000000000..3237147c8ba --- /dev/null +++ b/compiler/rustc_middle/src/ty/binding.rs @@ -0,0 +1,22 @@ +use rustc_hir::BindingAnnotation; +use rustc_hir::BindingAnnotation::*; +use rustc_hir::Mutability; + +#[derive(Clone, PartialEq, TyEncodable, TyDecodable, Debug, Copy, HashStable)] +pub enum BindingMode { + BindByReference(Mutability), + BindByValue(Mutability), +} + +CloneTypeFoldableAndLiftImpls! { BindingMode, } + +impl BindingMode { + pub fn convert(ba: BindingAnnotation) -> BindingMode { + match ba { + Unannotated => BindingMode::BindByValue(Mutability::Not), + Mutable => BindingMode::BindByValue(Mutability::Mut), + Ref => BindingMode::BindByReference(Mutability::Not), + RefMut => BindingMode::BindByReference(Mutability::Mut), + } + } +} diff --git a/compiler/rustc_middle/src/ty/cast.rs b/compiler/rustc_middle/src/ty/cast.rs new file mode 100644 index 00000000000..79a3008c364 --- /dev/null +++ b/compiler/rustc_middle/src/ty/cast.rs @@ -0,0 +1,67 @@ +// Helpers for handling cast expressions, used in both +// typeck and codegen. + +use crate::ty::{self, Ty}; + +use rustc_ast as ast; +use rustc_macros::HashStable; + +/// Types that are represented as ints. +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum IntTy { + U(ast::UintTy), + I, + CEnum, + Bool, + Char, +} + +// Valid types for the result of a non-coercion cast +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum CastTy<'tcx> { + /// Various types that are represented as ints and handled mostly + /// in the same way, merged for easier matching. + Int(IntTy), + /// Floating-Point types + Float, + /// Function Pointers + FnPtr, + /// Raw pointers + Ptr(ty::TypeAndMut<'tcx>), +} + +/// Cast Kind. See RFC 401 (or librustc_typeck/check/cast.rs) +#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum CastKind { + CoercionCast, + PtrPtrCast, + PtrAddrCast, + AddrPtrCast, + NumericCast, + EnumCast, + PrimIntCast, + U8CharCast, + ArrayPtrCast, + FnPtrPtrCast, + FnPtrAddrCast, +} + +impl<'tcx> CastTy<'tcx> { + /// Returns `Some` for integral/pointer casts. + /// casts like unsizing casts will return `None` + pub fn from_ty(t: Ty<'tcx>) -> Option<CastTy<'tcx>> { + match t.kind { + ty::Bool => Some(CastTy::Int(IntTy::Bool)), + ty::Char => Some(CastTy::Int(IntTy::Char)), + ty::Int(_) => Some(CastTy::Int(IntTy::I)), + ty::Infer(ty::InferTy::IntVar(_)) => Some(CastTy::Int(IntTy::I)), + ty::Infer(ty::InferTy::FloatVar(_)) => Some(CastTy::Float), + ty::Uint(u) => Some(CastTy::Int(IntTy::U(u))), + ty::Float(_) => Some(CastTy::Float), + ty::Adt(d, _) if d.is_enum() && d.is_payloadfree() => Some(CastTy::Int(IntTy::CEnum)), + ty::RawPtr(mt) => Some(CastTy::Ptr(mt)), + ty::FnPtr(..) => Some(CastTy::FnPtr), + _ => None, + } + } +} diff --git a/compiler/rustc_middle/src/ty/codec.rs b/compiler/rustc_middle/src/ty/codec.rs new file mode 100644 index 00000000000..291648869fb --- /dev/null +++ b/compiler/rustc_middle/src/ty/codec.rs @@ -0,0 +1,456 @@ +// This module contains some shared code for encoding and decoding various +// things from the `ty` module, and in particular implements support for +// "shorthands" which allow to have pointers back into the already encoded +// stream instead of re-encoding the same thing twice. +// +// The functionality in here is shared between persisting to crate metadata and +// persisting to incr. comp. caches. + +use crate::arena::ArenaAllocatable; +use crate::infer::canonical::{CanonicalVarInfo, CanonicalVarInfos}; +use crate::mir::{ + self, + interpret::{AllocId, Allocation}, +}; +use crate::ty::subst::SubstsRef; +use crate::ty::{self, List, Ty, TyCtxt}; +use rustc_data_structures::fx::FxHashMap; +use rustc_hir::def_id::{CrateNum, DefId}; +use rustc_serialize::{Decodable, Decoder, Encodable, Encoder}; +use rustc_span::Span; +use std::convert::{TryFrom, TryInto}; +use std::hash::Hash; +use std::intrinsics; +use std::marker::DiscriminantKind; + +/// The shorthand encoding uses an enum's variant index `usize` +/// and is offset by this value so it never matches a real variant. +/// This offset is also chosen so that the first byte is never < 0x80. +pub const SHORTHAND_OFFSET: usize = 0x80; + +pub trait EncodableWithShorthand<'tcx, E: TyEncoder<'tcx>>: Copy + Eq + Hash { + type Variant: Encodable<E>; + fn variant(&self) -> &Self::Variant; +} + +#[allow(rustc::usage_of_ty_tykind)] +impl<'tcx, E: TyEncoder<'tcx>> EncodableWithShorthand<'tcx, E> for Ty<'tcx> { + type Variant = ty::TyKind<'tcx>; + fn variant(&self) -> &Self::Variant { + &self.kind + } +} + +impl<'tcx, E: TyEncoder<'tcx>> EncodableWithShorthand<'tcx, E> for ty::Predicate<'tcx> { + type Variant = ty::PredicateKind<'tcx>; + fn variant(&self) -> &Self::Variant { + self.kind() + } +} + +pub trait OpaqueEncoder: Encoder { + fn opaque(&mut self) -> &mut rustc_serialize::opaque::Encoder; + fn encoder_position(&self) -> usize; +} + +impl OpaqueEncoder for rustc_serialize::opaque::Encoder { + #[inline] + fn opaque(&mut self) -> &mut rustc_serialize::opaque::Encoder { + self + } + #[inline] + fn encoder_position(&self) -> usize { + self.position() + } +} + +pub trait TyEncoder<'tcx>: Encoder { + const CLEAR_CROSS_CRATE: bool; + + fn tcx(&self) -> TyCtxt<'tcx>; + fn position(&self) -> usize; + fn type_shorthands(&mut self) -> &mut FxHashMap<Ty<'tcx>, usize>; + fn predicate_shorthands(&mut self) -> &mut FxHashMap<ty::Predicate<'tcx>, usize>; + fn encode_alloc_id(&mut self, alloc_id: &AllocId) -> Result<(), Self::Error>; +} + +/// Trait for decoding to a reference. +/// +/// This is a separate trait from `Decodable` so that we can implement it for +/// upstream types, such as `FxHashSet`. +/// +/// The `TyDecodable` derive macro will use this trait for fields that are +/// references (and don't use a type alias to hide that). +/// +/// `Decodable` can still be implemented in cases where `Decodable` is required +/// by a trait bound. +pub trait RefDecodable<'tcx, D: TyDecoder<'tcx>> { + fn decode(d: &mut D) -> Result<&'tcx Self, D::Error>; +} + +/// Encode the given value or a previously cached shorthand. +pub fn encode_with_shorthand<E, T, M>(encoder: &mut E, value: &T, cache: M) -> Result<(), E::Error> +where + E: TyEncoder<'tcx>, + M: for<'b> Fn(&'b mut E) -> &'b mut FxHashMap<T, usize>, + T: EncodableWithShorthand<'tcx, E>, + <T::Variant as DiscriminantKind>::Discriminant: Ord + TryFrom<usize>, +{ + let existing_shorthand = cache(encoder).get(value).copied(); + if let Some(shorthand) = existing_shorthand { + return encoder.emit_usize(shorthand); + } + + let variant = value.variant(); + + let start = encoder.position(); + variant.encode(encoder)?; + let len = encoder.position() - start; + + // The shorthand encoding uses the same usize as the + // discriminant, with an offset so they can't conflict. + let discriminant = intrinsics::discriminant_value(variant); + assert!(discriminant < SHORTHAND_OFFSET.try_into().ok().unwrap()); + + let shorthand = start + SHORTHAND_OFFSET; + + // Get the number of bits that leb128 could fit + // in the same space as the fully encoded type. + let leb128_bits = len * 7; + + // Check that the shorthand is a not longer than the + // full encoding itself, i.e., it's an obvious win. + if leb128_bits >= 64 || (shorthand as u64) < (1 << leb128_bits) { + cache(encoder).insert(*value, shorthand); + } + + Ok(()) +} + +impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Ty<'tcx> { + fn encode(&self, e: &mut E) -> Result<(), E::Error> { + encode_with_shorthand(e, self, TyEncoder::type_shorthands) + } +} + +impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for ty::Predicate<'tcx> { + fn encode(&self, e: &mut E) -> Result<(), E::Error> { + encode_with_shorthand(e, self, TyEncoder::predicate_shorthands) + } +} + +impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for AllocId { + fn encode(&self, e: &mut E) -> Result<(), E::Error> { + e.encode_alloc_id(self) + } +} + +macro_rules! encodable_via_deref { + ($($t:ty),+) => { + $(impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for $t { + fn encode(&self, e: &mut E) -> Result<(), E::Error> { + (**self).encode(e) + } + })* + } +} + +encodable_via_deref! { + &'tcx ty::TypeckResults<'tcx>, + ty::Region<'tcx>, + &'tcx mir::Body<'tcx>, + &'tcx mir::UnsafetyCheckResult, + &'tcx mir::BorrowCheckResult<'tcx> +} + +pub trait TyDecoder<'tcx>: Decoder { + const CLEAR_CROSS_CRATE: bool; + + fn tcx(&self) -> TyCtxt<'tcx>; + + fn peek_byte(&self) -> u8; + + fn position(&self) -> usize; + + fn cached_ty_for_shorthand<F>( + &mut self, + shorthand: usize, + or_insert_with: F, + ) -> Result<Ty<'tcx>, Self::Error> + where + F: FnOnce(&mut Self) -> Result<Ty<'tcx>, Self::Error>; + + fn cached_predicate_for_shorthand<F>( + &mut self, + shorthand: usize, + or_insert_with: F, + ) -> Result<ty::Predicate<'tcx>, Self::Error> + where + F: FnOnce(&mut Self) -> Result<ty::Predicate<'tcx>, Self::Error>; + + fn with_position<F, R>(&mut self, pos: usize, f: F) -> R + where + F: FnOnce(&mut Self) -> R; + + fn map_encoded_cnum_to_current(&self, cnum: CrateNum) -> CrateNum; + + fn positioned_at_shorthand(&self) -> bool { + (self.peek_byte() & (SHORTHAND_OFFSET as u8)) != 0 + } + + fn decode_alloc_id(&mut self) -> Result<AllocId, Self::Error>; +} + +#[inline] +pub fn decode_arena_allocable<'tcx, D, T: ArenaAllocatable<'tcx> + Decodable<D>>( + decoder: &mut D, +) -> Result<&'tcx T, D::Error> +where + D: TyDecoder<'tcx>, +{ + Ok(decoder.tcx().arena.alloc(Decodable::decode(decoder)?)) +} + +#[inline] +pub fn decode_arena_allocable_slice<'tcx, D, T: ArenaAllocatable<'tcx> + Decodable<D>>( + decoder: &mut D, +) -> Result<&'tcx [T], D::Error> +where + D: TyDecoder<'tcx>, +{ + Ok(decoder.tcx().arena.alloc_from_iter(<Vec<T> as Decodable<D>>::decode(decoder)?)) +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Ty<'tcx> { + #[allow(rustc::usage_of_ty_tykind)] + fn decode(decoder: &mut D) -> Result<Ty<'tcx>, D::Error> { + // Handle shorthands first, if we have an usize > 0x80. + if decoder.positioned_at_shorthand() { + let pos = decoder.read_usize()?; + assert!(pos >= SHORTHAND_OFFSET); + let shorthand = pos - SHORTHAND_OFFSET; + + decoder.cached_ty_for_shorthand(shorthand, |decoder| { + decoder.with_position(shorthand, Ty::decode) + }) + } else { + let tcx = decoder.tcx(); + Ok(tcx.mk_ty(ty::TyKind::decode(decoder)?)) + } + } +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for ty::Predicate<'tcx> { + fn decode(decoder: &mut D) -> Result<ty::Predicate<'tcx>, D::Error> { + // Handle shorthands first, if we have an usize > 0x80. + let predicate_kind = if decoder.positioned_at_shorthand() { + let pos = decoder.read_usize()?; + assert!(pos >= SHORTHAND_OFFSET); + let shorthand = pos - SHORTHAND_OFFSET; + + decoder.with_position(shorthand, ty::PredicateKind::decode) + } else { + ty::PredicateKind::decode(decoder) + }?; + let predicate = decoder.tcx().mk_predicate(predicate_kind); + Ok(predicate) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for SubstsRef<'tcx> { + fn decode(decoder: &mut D) -> Result<Self, D::Error> { + let len = decoder.read_usize()?; + let tcx = decoder.tcx(); + Ok(tcx.mk_substs((0..len).map(|_| Decodable::decode(decoder)))?) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for mir::Place<'tcx> { + fn decode(decoder: &mut D) -> Result<Self, D::Error> { + let local: mir::Local = Decodable::decode(decoder)?; + let len = decoder.read_usize()?; + let projection: &'tcx List<mir::PlaceElem<'tcx>> = + decoder.tcx().mk_place_elems((0..len).map(|_| Decodable::decode(decoder)))?; + Ok(mir::Place { local, projection }) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for ty::Region<'tcx> { + fn decode(decoder: &mut D) -> Result<Self, D::Error> { + Ok(decoder.tcx().mk_region(Decodable::decode(decoder)?)) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for CanonicalVarInfos<'tcx> { + fn decode(decoder: &mut D) -> Result<Self, D::Error> { + let len = decoder.read_usize()?; + let interned: Result<Vec<CanonicalVarInfo>, _> = + (0..len).map(|_| Decodable::decode(decoder)).collect(); + Ok(decoder.tcx().intern_canonical_var_infos(interned?.as_slice())) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for AllocId { + fn decode(decoder: &mut D) -> Result<Self, D::Error> { + decoder.decode_alloc_id() + } +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for ty::SymbolName<'tcx> { + fn decode(decoder: &mut D) -> Result<Self, D::Error> { + Ok(ty::SymbolName::new(decoder.tcx(), &decoder.read_str()?)) + } +} + +macro_rules! impl_decodable_via_ref { + ($($t:ty),+) => { + $(impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for $t { + fn decode(decoder: &mut D) -> Result<Self, D::Error> { + RefDecodable::decode(decoder) + } + })* + } +} + +impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for ty::AdtDef { + fn decode(decoder: &mut D) -> Result<&'tcx Self, D::Error> { + let def_id = <DefId as Decodable<D>>::decode(decoder)?; + Ok(decoder.tcx().adt_def(def_id)) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for ty::List<Ty<'tcx>> { + fn decode(decoder: &mut D) -> Result<&'tcx Self, D::Error> { + let len = decoder.read_usize()?; + Ok(decoder.tcx().mk_type_list((0..len).map(|_| Decodable::decode(decoder)))?) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for ty::List<ty::ExistentialPredicate<'tcx>> { + fn decode(decoder: &mut D) -> Result<&'tcx Self, D::Error> { + let len = decoder.read_usize()?; + Ok(decoder.tcx().mk_existential_predicates((0..len).map(|_| Decodable::decode(decoder)))?) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for ty::Const<'tcx> { + fn decode(decoder: &mut D) -> Result<&'tcx Self, D::Error> { + Ok(decoder.tcx().mk_const(Decodable::decode(decoder)?)) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for Allocation { + fn decode(decoder: &mut D) -> Result<&'tcx Self, D::Error> { + Ok(decoder.tcx().intern_const_alloc(Decodable::decode(decoder)?)) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for [(ty::Predicate<'tcx>, Span)] { + fn decode(decoder: &mut D) -> Result<&'tcx Self, D::Error> { + Ok(decoder.tcx().arena.alloc_from_iter( + (0..decoder.read_usize()?) + .map(|_| Decodable::decode(decoder)) + .collect::<Result<Vec<_>, _>>()?, + )) + } +} + +impl_decodable_via_ref! { + &'tcx ty::TypeckResults<'tcx>, + &'tcx ty::List<Ty<'tcx>>, + &'tcx ty::List<ty::ExistentialPredicate<'tcx>>, + &'tcx Allocation, + &'tcx mir::Body<'tcx>, + &'tcx mir::UnsafetyCheckResult, + &'tcx mir::BorrowCheckResult<'tcx> +} + +#[macro_export] +macro_rules! __impl_decoder_methods { + ($($name:ident -> $ty:ty;)*) => { + $( + #[inline] + fn $name(&mut self) -> Result<$ty, Self::Error> { + self.opaque.$name() + } + )* + } +} + +macro_rules! impl_arena_allocatable_decoder { + ([]$args:tt) => {}; + ([decode $(, $attrs:ident)*] + [[$name:ident: $ty:ty], $tcx:lifetime]) => { + impl<$tcx, D: TyDecoder<$tcx>> RefDecodable<$tcx, D> for $ty { + #[inline] + fn decode(decoder: &mut D) -> Result<&$tcx Self, D::Error> { + decode_arena_allocable(decoder) + } + } + + impl<$tcx, D: TyDecoder<$tcx>> RefDecodable<$tcx, D> for [$ty] { + #[inline] + fn decode(decoder: &mut D) -> Result<&$tcx Self, D::Error> { + decode_arena_allocable_slice(decoder) + } + } + }; + ([$ignore:ident $(, $attrs:ident)*]$args:tt) => { + impl_arena_allocatable_decoder!([$($attrs),*]$args); + }; +} + +macro_rules! impl_arena_allocatable_decoders { + ([], [$($a:tt $name:ident: $ty:ty,)*], $tcx:lifetime) => { + $( + impl_arena_allocatable_decoder!($a [[$name: $ty], $tcx]); + )* + } +} + +rustc_hir::arena_types!(impl_arena_allocatable_decoders, [], 'tcx); +arena_types!(impl_arena_allocatable_decoders, [], 'tcx); + +#[macro_export] +macro_rules! implement_ty_decoder { + ($DecoderName:ident <$($typaram:tt),*>) => { + mod __ty_decoder_impl { + use std::borrow::Cow; + use rustc_serialize::Decoder; + + use super::$DecoderName; + + impl<$($typaram ),*> Decoder for $DecoderName<$($typaram),*> { + type Error = String; + + $crate::__impl_decoder_methods! { + read_nil -> (); + + read_u128 -> u128; + read_u64 -> u64; + read_u32 -> u32; + read_u16 -> u16; + read_u8 -> u8; + read_usize -> usize; + + read_i128 -> i128; + read_i64 -> i64; + read_i32 -> i32; + read_i16 -> i16; + read_i8 -> i8; + read_isize -> isize; + + read_bool -> bool; + read_f64 -> f64; + read_f32 -> f32; + read_char -> char; + read_str -> Cow<'_, str>; + } + + fn error(&mut self, err: &str) -> Self::Error { + self.opaque.error(err) + } + } + } + } +} diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs new file mode 100644 index 00000000000..64faacc1c0b --- /dev/null +++ b/compiler/rustc_middle/src/ty/consts.rs @@ -0,0 +1,203 @@ +use crate::mir::interpret::ConstValue; +use crate::mir::interpret::{LitToConstInput, Scalar}; +use crate::ty::subst::InternalSubsts; +use crate::ty::{self, Ty, TyCtxt}; +use crate::ty::{ParamEnv, ParamEnvAnd}; +use rustc_errors::ErrorReported; +use rustc_hir as hir; +use rustc_hir::def_id::LocalDefId; +use rustc_macros::HashStable; + +mod int; +mod kind; + +pub use int::*; +pub use kind::*; + +/// Typed constant value. +#[derive(Copy, Clone, Debug, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)] +#[derive(HashStable)] +pub struct Const<'tcx> { + pub ty: Ty<'tcx>, + + pub val: ConstKind<'tcx>, +} + +#[cfg(target_arch = "x86_64")] +static_assert_size!(Const<'_>, 48); + +impl<'tcx> Const<'tcx> { + /// Literals and const generic parameters are eagerly converted to a constant, everything else + /// becomes `Unevaluated`. + pub fn from_anon_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx Self { + Self::from_opt_const_arg_anon_const(tcx, ty::WithOptConstParam::unknown(def_id)) + } + + pub fn from_opt_const_arg_anon_const( + tcx: TyCtxt<'tcx>, + def: ty::WithOptConstParam<LocalDefId>, + ) -> &'tcx Self { + debug!("Const::from_anon_const(def={:?})", def); + + let hir_id = tcx.hir().local_def_id_to_hir_id(def.did); + + let body_id = match tcx.hir().get(hir_id) { + hir::Node::AnonConst(ac) => ac.body, + _ => span_bug!( + tcx.def_span(def.did.to_def_id()), + "from_anon_const can only process anonymous constants" + ), + }; + + let expr = &tcx.hir().body(body_id).value; + + let ty = tcx.type_of(def.def_id_for_type_of()); + + let lit_input = match expr.kind { + hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }), + hir::ExprKind::Unary(hir::UnOp::UnNeg, ref expr) => match expr.kind { + hir::ExprKind::Lit(ref lit) => { + Some(LitToConstInput { lit: &lit.node, ty, neg: true }) + } + _ => None, + }, + _ => None, + }; + + if let Some(lit_input) = lit_input { + // If an error occurred, ignore that it's a literal and leave reporting the error up to + // mir. + if let Ok(c) = tcx.at(expr.span).lit_to_const(lit_input) { + return c; + } else { + tcx.sess.delay_span_bug(expr.span, "Const::from_anon_const: couldn't lit_to_const"); + } + } + + // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments + // currently have to be wrapped in curly brackets, so it's necessary to special-case. + let expr = match &expr.kind { + hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => { + block.expr.as_ref().unwrap() + } + _ => expr, + }; + + use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath}; + let val = match expr.kind { + ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => { + // Find the name and index of the const parameter by indexing the generics of + // the parent item and construct a `ParamConst`. + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local()); + let item_id = tcx.hir().get_parent_node(hir_id); + let item_def_id = tcx.hir().local_def_id(item_id); + let generics = tcx.generics_of(item_def_id.to_def_id()); + let index = + generics.param_def_id_to_index[&tcx.hir().local_def_id(hir_id).to_def_id()]; + let name = tcx.hir().name(hir_id); + ty::ConstKind::Param(ty::ParamConst::new(index, name)) + } + _ => ty::ConstKind::Unevaluated( + def.to_global(), + InternalSubsts::identity_for_item(tcx, def.did.to_def_id()), + None, + ), + }; + + tcx.mk_const(ty::Const { val, ty }) + } + + #[inline] + /// Interns the given value as a constant. + pub fn from_value(tcx: TyCtxt<'tcx>, val: ConstValue<'tcx>, ty: Ty<'tcx>) -> &'tcx Self { + tcx.mk_const(Self { val: ConstKind::Value(val), ty }) + } + + #[inline] + /// Interns the given scalar as a constant. + pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self { + Self::from_value(tcx, ConstValue::Scalar(val), ty) + } + + #[inline] + /// Creates a constant with the given integer value and interns it. + pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> &'tcx Self { + let size = tcx + .layout_of(ty) + .unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e)) + .size; + Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value) + } + + #[inline] + /// Creates an interned zst constant. + pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Self { + Self::from_scalar(tcx, Scalar::zst(), ty) + } + + #[inline] + /// Creates an interned bool constant. + pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> &'tcx Self { + Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool)) + } + + #[inline] + /// Creates an interned usize constant. + pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> &'tcx Self { + Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize)) + } + + #[inline] + /// Attempts to evaluate the given constant to bits. Can fail to evaluate in the presence of + /// generics (or erroneous code) or if the value can't be represented as bits (e.g. because it + /// contains const generic parameters or pointers). + pub fn try_eval_bits( + &self, + tcx: TyCtxt<'tcx>, + param_env: ParamEnv<'tcx>, + ty: Ty<'tcx>, + ) -> Option<u128> { + assert_eq!(self.ty, ty); + let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size; + // if `ty` does not depend on generic parameters, use an empty param_env + self.val.eval(tcx, param_env).try_to_bits(size) + } + + #[inline] + pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> { + self.val.eval(tcx, param_env).try_to_bool() + } + + #[inline] + pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u64> { + self.val.eval(tcx, param_env).try_to_machine_usize(tcx) + } + + #[inline] + /// Tries to evaluate the constant if it is `Unevaluated`. If that doesn't succeed, return the + /// unevaluated constant. + pub fn eval(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> &Const<'tcx> { + if let Some(val) = self.val.try_eval(tcx, param_env) { + match val { + Ok(val) => Const::from_value(tcx, val, self.ty), + Err(ErrorReported) => tcx.const_error(self.ty), + } + } else { + self + } + } + + #[inline] + /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type. + pub fn eval_bits(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 { + self.try_eval_bits(tcx, param_env, ty) + .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self)) + } + + #[inline] + /// Panics if the value cannot be evaluated or doesn't contain a valid `usize`. + pub fn eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u64 { + self.try_eval_usize(tcx, param_env) + .unwrap_or_else(|| bug!("expected usize, got {:#?}", self)) + } +} diff --git a/compiler/rustc_middle/src/ty/consts/int.rs b/compiler/rustc_middle/src/ty/consts/int.rs new file mode 100644 index 00000000000..ced0429deab --- /dev/null +++ b/compiler/rustc_middle/src/ty/consts/int.rs @@ -0,0 +1,111 @@ +use crate::mir::interpret::truncate; +use rustc_target::abi::Size; + +#[derive(Copy, Clone)] +/// A type for representing any integer. Only used for printing. +// FIXME: Use this for the integer-tree representation needed for type level ints and +// const generics? +pub struct ConstInt { + /// Number of bytes of the integer. Only 1, 2, 4, 8, 16 are legal values. + size: u8, + /// Whether the value is of a signed integer type. + signed: bool, + /// Whether the value is a `usize` or `isize` type. + is_ptr_sized_integral: bool, + /// Raw memory of the integer. All bytes beyond the `size` are unused and must be zero. + raw: u128, +} + +impl ConstInt { + pub fn new(raw: u128, size: Size, signed: bool, is_ptr_sized_integral: bool) -> Self { + assert!(raw <= truncate(u128::MAX, size)); + Self { raw, size: size.bytes() as u8, signed, is_ptr_sized_integral } + } +} + +impl std::fmt::Debug for ConstInt { + fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + let Self { size, signed, raw, is_ptr_sized_integral } = *self; + if signed { + let bit_size = size * 8; + let min = 1u128 << (bit_size - 1); + let max = min - 1; + if raw == min { + match (size, is_ptr_sized_integral) { + (_, true) => write!(fmt, "isize::MIN"), + (1, _) => write!(fmt, "i8::MIN"), + (2, _) => write!(fmt, "i16::MIN"), + (4, _) => write!(fmt, "i32::MIN"), + (8, _) => write!(fmt, "i64::MIN"), + (16, _) => write!(fmt, "i128::MIN"), + _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed), + } + } else if raw == max { + match (size, is_ptr_sized_integral) { + (_, true) => write!(fmt, "isize::MAX"), + (1, _) => write!(fmt, "i8::MAX"), + (2, _) => write!(fmt, "i16::MAX"), + (4, _) => write!(fmt, "i32::MAX"), + (8, _) => write!(fmt, "i64::MAX"), + (16, _) => write!(fmt, "i128::MAX"), + _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed), + } + } else { + match size { + 1 => write!(fmt, "{}", raw as i8)?, + 2 => write!(fmt, "{}", raw as i16)?, + 4 => write!(fmt, "{}", raw as i32)?, + 8 => write!(fmt, "{}", raw as i64)?, + 16 => write!(fmt, "{}", raw as i128)?, + _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed), + } + if fmt.alternate() { + match (size, is_ptr_sized_integral) { + (_, true) => write!(fmt, "_isize")?, + (1, _) => write!(fmt, "_i8")?, + (2, _) => write!(fmt, "_i16")?, + (4, _) => write!(fmt, "_i32")?, + (8, _) => write!(fmt, "_i64")?, + (16, _) => write!(fmt, "_i128")?, + _ => bug!(), + } + } + Ok(()) + } + } else { + let max = truncate(u128::MAX, Size::from_bytes(size)); + if raw == max { + match (size, is_ptr_sized_integral) { + (_, true) => write!(fmt, "usize::MAX"), + (1, _) => write!(fmt, "u8::MAX"), + (2, _) => write!(fmt, "u16::MAX"), + (4, _) => write!(fmt, "u32::MAX"), + (8, _) => write!(fmt, "u64::MAX"), + (16, _) => write!(fmt, "u128::MAX"), + _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed), + } + } else { + match size { + 1 => write!(fmt, "{}", raw as u8)?, + 2 => write!(fmt, "{}", raw as u16)?, + 4 => write!(fmt, "{}", raw as u32)?, + 8 => write!(fmt, "{}", raw as u64)?, + 16 => write!(fmt, "{}", raw as u128)?, + _ => bug!("ConstInt 0x{:x} with size = {} and signed = {}", raw, size, signed), + } + if fmt.alternate() { + match (size, is_ptr_sized_integral) { + (_, true) => write!(fmt, "_usize")?, + (1, _) => write!(fmt, "_u8")?, + (2, _) => write!(fmt, "_u16")?, + (4, _) => write!(fmt, "_u32")?, + (8, _) => write!(fmt, "_u64")?, + (16, _) => write!(fmt, "_u128")?, + _ => bug!(), + } + } + Ok(()) + } + } + } +} diff --git a/compiler/rustc_middle/src/ty/consts/kind.rs b/compiler/rustc_middle/src/ty/consts/kind.rs new file mode 100644 index 00000000000..ede28522000 --- /dev/null +++ b/compiler/rustc_middle/src/ty/consts/kind.rs @@ -0,0 +1,139 @@ +use crate::mir::interpret::ConstValue; +use crate::mir::interpret::Scalar; +use crate::mir::Promoted; +use crate::ty::subst::{InternalSubsts, SubstsRef}; +use crate::ty::ParamEnv; +use crate::ty::{self, TyCtxt, TypeFoldable}; +use rustc_errors::ErrorReported; +use rustc_hir::def_id::DefId; +use rustc_macros::HashStable; +use rustc_target::abi::Size; + +/// Represents a constant in Rust. +#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)] +#[derive(HashStable)] +pub enum ConstKind<'tcx> { + /// A const generic parameter. + Param(ty::ParamConst), + + /// Infer the value of the const. + Infer(InferConst<'tcx>), + + /// Bound const variable, used only when preparing a trait query. + Bound(ty::DebruijnIndex, ty::BoundVar), + + /// A placeholder const - universally quantified higher-ranked const. + Placeholder(ty::PlaceholderConst), + + /// Used in the HIR by using `Unevaluated` everywhere and later normalizing to one of the other + /// variants when the code is monomorphic enough for that. + Unevaluated(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>, Option<Promoted>), + + /// Used to hold computed value. + Value(ConstValue<'tcx>), + + /// A placeholder for a const which could not be computed; this is + /// propagated to avoid useless error messages. + Error(ty::DelaySpanBugEmitted), +} + +#[cfg(target_arch = "x86_64")] +static_assert_size!(ConstKind<'_>, 40); + +impl<'tcx> ConstKind<'tcx> { + #[inline] + pub fn try_to_value(self) -> Option<ConstValue<'tcx>> { + if let ConstKind::Value(val) = self { Some(val) } else { None } + } + + #[inline] + pub fn try_to_scalar(self) -> Option<Scalar> { + self.try_to_value()?.try_to_scalar() + } + + #[inline] + pub fn try_to_bits(self, size: Size) -> Option<u128> { + self.try_to_value()?.try_to_bits(size) + } + + #[inline] + pub fn try_to_bool(self) -> Option<bool> { + self.try_to_value()?.try_to_bool() + } + + #[inline] + pub fn try_to_machine_usize(self, tcx: TyCtxt<'tcx>) -> Option<u64> { + self.try_to_value()?.try_to_machine_usize(tcx) + } +} + +/// An inference variable for a const, for use in const generics. +#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)] +#[derive(HashStable)] +pub enum InferConst<'tcx> { + /// Infer the value of the const. + Var(ty::ConstVid<'tcx>), + /// A fresh const variable. See `infer::freshen` for more details. + Fresh(u32), +} + +impl<'tcx> ConstKind<'tcx> { + #[inline] + /// Tries to evaluate the constant if it is `Unevaluated`. If that doesn't succeed, return the + /// unevaluated constant. + pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Self { + self.try_eval(tcx, param_env).and_then(Result::ok).map(ConstKind::Value).unwrap_or(self) + } + + #[inline] + /// Tries to evaluate the constant if it is `Unevaluated`. If that isn't possible or necessary + /// return `None`. + pub(super) fn try_eval( + self, + tcx: TyCtxt<'tcx>, + param_env: ParamEnv<'tcx>, + ) -> Option<Result<ConstValue<'tcx>, ErrorReported>> { + if let ConstKind::Unevaluated(def, substs, promoted) = self { + use crate::mir::interpret::ErrorHandled; + + // HACK(eddyb) this erases lifetimes even though `const_eval_resolve` + // also does later, but we want to do it before checking for + // inference variables. + // Note that we erase regions *before* calling `with_reveal_all_normalized`, + // so that we don't try to invoke this query with + // any region variables. + let param_env_and_substs = tcx + .erase_regions(¶m_env) + .with_reveal_all_normalized(tcx) + .and(tcx.erase_regions(&substs)); + + // HACK(eddyb) when the query key would contain inference variables, + // attempt using identity substs and `ParamEnv` instead, that will succeed + // when the expression doesn't depend on any parameters. + // FIXME(eddyb, skinny121) pass `InferCtxt` into here when it's available, so that + // we can call `infcx.const_eval_resolve` which handles inference variables. + let param_env_and_substs = if param_env_and_substs.needs_infer() { + tcx.param_env(def.did).and(InternalSubsts::identity_for_item(tcx, def.did)) + } else { + param_env_and_substs + }; + + // FIXME(eddyb) maybe the `const_eval_*` methods should take + // `ty::ParamEnvAnd<SubstsRef>` instead of having them separate. + let (param_env, substs) = param_env_and_substs.into_parts(); + // try to resolve e.g. associated constants to their definition on an impl, and then + // evaluate the const. + match tcx.const_eval_resolve(param_env, def, substs, promoted, None) { + // NOTE(eddyb) `val` contains no lifetimes/types/consts, + // and we use the original type, so nothing from `substs` + // (which may be identity substs, see above), + // can leak through `val` into the const we return. + Ok(val) => Some(Ok(val)), + Err(ErrorHandled::TooGeneric | ErrorHandled::Linted) => None, + Err(ErrorHandled::Reported(e)) => Some(Err(e)), + } + } else { + None + } + } +} diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs new file mode 100644 index 00000000000..18ae744cb1e --- /dev/null +++ b/compiler/rustc_middle/src/ty/context.rs @@ -0,0 +1,2764 @@ +//! Type context book-keeping. + +use crate::arena::Arena; +use crate::dep_graph::{self, DepConstructor, DepGraph}; +use crate::hir::exports::ExportMap; +use crate::ich::{NodeIdHashingMode, StableHashingContext}; +use crate::infer::canonical::{Canonical, CanonicalVarInfo, CanonicalVarInfos}; +use crate::lint::{struct_lint_level, LintDiagnosticBuilder, LintSource}; +use crate::middle; +use crate::middle::cstore::{CrateStoreDyn, EncodedMetadata}; +use crate::middle::resolve_lifetime::{self, ObjectLifetimeDefault}; +use crate::middle::stability; +use crate::mir::interpret::{self, Allocation, ConstValue, Scalar}; +use crate::mir::{Body, Field, Local, Place, PlaceElem, ProjectionKind, Promoted}; +use crate::traits; +use crate::ty::query::{self, TyCtxtAt}; +use crate::ty::steal::Steal; +use crate::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSubsts}; +use crate::ty::TyKind::*; +use crate::ty::{ + self, AdtDef, AdtKind, BindingMode, BoundVar, CanonicalPolyFnSig, Const, ConstVid, DefIdTree, + ExistentialPredicate, FloatVar, FloatVid, GenericParamDefKind, InferConst, InferTy, IntVar, + IntVid, List, ParamConst, ParamTy, PolyFnSig, Predicate, PredicateInner, PredicateKind, + ProjectionTy, Region, RegionKind, ReprOptions, TraitObjectVisitor, Ty, TyKind, TyS, TyVar, + TyVid, TypeAndMut, +}; +use rustc_ast as ast; +use rustc_ast::expand::allocator::AllocatorKind; +use rustc_attr as attr; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_data_structures::profiling::SelfProfilerRef; +use rustc_data_structures::sharded::{IntoPointer, ShardedHashMap}; +use rustc_data_structures::stable_hasher::{ + hash_stable_hashmap, HashStable, StableHasher, StableVec, +}; +use rustc_data_structures::sync::{self, Lock, Lrc, WorkerLocal}; +use rustc_errors::ErrorReported; +use rustc_hir as hir; +use rustc_hir::def::{DefKind, Res}; +use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LOCAL_CRATE}; +use rustc_hir::definitions::{DefPathHash, Definitions}; +use rustc_hir::intravisit::Visitor; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{HirId, ItemKind, ItemLocalId, ItemLocalMap, ItemLocalSet, Node, TraitCandidate}; +use rustc_index::vec::{Idx, IndexVec}; +use rustc_macros::HashStable; +use rustc_session::config::{BorrowckMode, CrateType, OutputFilenames}; +use rustc_session::lint::{Level, Lint}; +use rustc_session::Session; +use rustc_span::source_map::MultiSpan; +use rustc_span::symbol::{kw, sym, Symbol}; +use rustc_span::{Span, DUMMY_SP}; +use rustc_target::abi::{Layout, TargetDataLayout, VariantIdx}; +use rustc_target::spec::abi; + +use smallvec::SmallVec; +use std::any::Any; +use std::borrow::Borrow; +use std::cmp::Ordering; +use std::collections::hash_map::{self, Entry}; +use std::fmt; +use std::hash::{Hash, Hasher}; +use std::iter; +use std::mem; +use std::ops::{Bound, Deref}; +use std::sync::Arc; + +/// A type that is not publicly constructable. This prevents people from making `TyKind::Error` +/// except through `tcx.err*()`, which are in this module. +#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)] +#[derive(TyEncodable, TyDecodable, HashStable)] +pub struct DelaySpanBugEmitted(()); + +type InternedSet<'tcx, T> = ShardedHashMap<Interned<'tcx, T>, ()>; + +pub struct CtxtInterners<'tcx> { + /// The arena that types, regions, etc. are allocated from. + arena: &'tcx WorkerLocal<Arena<'tcx>>, + + /// Specifically use a speedy hash algorithm for these hash sets, since + /// they're accessed quite often. + type_: InternedSet<'tcx, TyS<'tcx>>, + type_list: InternedSet<'tcx, List<Ty<'tcx>>>, + substs: InternedSet<'tcx, InternalSubsts<'tcx>>, + canonical_var_infos: InternedSet<'tcx, List<CanonicalVarInfo>>, + region: InternedSet<'tcx, RegionKind>, + existential_predicates: InternedSet<'tcx, List<ExistentialPredicate<'tcx>>>, + predicate: InternedSet<'tcx, PredicateInner<'tcx>>, + predicates: InternedSet<'tcx, List<Predicate<'tcx>>>, + projs: InternedSet<'tcx, List<ProjectionKind>>, + place_elems: InternedSet<'tcx, List<PlaceElem<'tcx>>>, + const_: InternedSet<'tcx, Const<'tcx>>, + + chalk_environment_clause_list: InternedSet<'tcx, List<traits::ChalkEnvironmentClause<'tcx>>>, +} + +impl<'tcx> CtxtInterners<'tcx> { + fn new(arena: &'tcx WorkerLocal<Arena<'tcx>>) -> CtxtInterners<'tcx> { + CtxtInterners { + arena, + type_: Default::default(), + type_list: Default::default(), + substs: Default::default(), + region: Default::default(), + existential_predicates: Default::default(), + canonical_var_infos: Default::default(), + predicate: Default::default(), + predicates: Default::default(), + projs: Default::default(), + place_elems: Default::default(), + const_: Default::default(), + chalk_environment_clause_list: Default::default(), + } + } + + /// Interns a type. + #[allow(rustc::usage_of_ty_tykind)] + #[inline(never)] + fn intern_ty(&self, kind: TyKind<'tcx>) -> Ty<'tcx> { + self.type_ + .intern(kind, |kind| { + let flags = super::flags::FlagComputation::for_kind(&kind); + + let ty_struct = TyS { + kind, + flags: flags.flags, + outer_exclusive_binder: flags.outer_exclusive_binder, + }; + + Interned(self.arena.alloc(ty_struct)) + }) + .0 + } + + #[inline(never)] + fn intern_predicate(&self, kind: PredicateKind<'tcx>) -> &'tcx PredicateInner<'tcx> { + self.predicate + .intern(kind, |kind| { + let flags = super::flags::FlagComputation::for_predicate(&kind); + + let predicate_struct = PredicateInner { + kind, + flags: flags.flags, + outer_exclusive_binder: flags.outer_exclusive_binder, + }; + + Interned(self.arena.alloc(predicate_struct)) + }) + .0 + } +} + +pub struct CommonTypes<'tcx> { + pub unit: Ty<'tcx>, + pub bool: Ty<'tcx>, + pub char: Ty<'tcx>, + pub isize: Ty<'tcx>, + pub i8: Ty<'tcx>, + pub i16: Ty<'tcx>, + pub i32: Ty<'tcx>, + pub i64: Ty<'tcx>, + pub i128: Ty<'tcx>, + pub usize: Ty<'tcx>, + pub u8: Ty<'tcx>, + pub u16: Ty<'tcx>, + pub u32: Ty<'tcx>, + pub u64: Ty<'tcx>, + pub u128: Ty<'tcx>, + pub f32: Ty<'tcx>, + pub f64: Ty<'tcx>, + pub str_: Ty<'tcx>, + pub never: Ty<'tcx>, + pub self_param: Ty<'tcx>, + + /// Dummy type used for the `Self` of a `TraitRef` created for converting + /// a trait object, and which gets removed in `ExistentialTraitRef`. + /// This type must not appear anywhere in other converted types. + pub trait_object_dummy_self: Ty<'tcx>, +} + +pub struct CommonLifetimes<'tcx> { + /// `ReEmpty` in the root universe. + pub re_root_empty: Region<'tcx>, + + /// `ReStatic` + pub re_static: Region<'tcx>, + + /// Erased region, used after type-checking + pub re_erased: Region<'tcx>, +} + +pub struct CommonConsts<'tcx> { + pub unit: &'tcx Const<'tcx>, +} + +pub struct LocalTableInContext<'a, V> { + hir_owner: LocalDefId, + data: &'a ItemLocalMap<V>, +} + +/// Validate that the given HirId (respectively its `local_id` part) can be +/// safely used as a key in the maps of a TypeckResults. For that to be +/// the case, the HirId must have the same `owner` as all the other IDs in +/// this table (signified by `hir_owner`). Otherwise the HirId +/// would be in a different frame of reference and using its `local_id` +/// would result in lookup errors, or worse, in silently wrong data being +/// stored/returned. +fn validate_hir_id_for_typeck_results(hir_owner: LocalDefId, hir_id: hir::HirId) { + if hir_id.owner != hir_owner { + ty::tls::with(|tcx| { + bug!( + "node {} with HirId::owner {:?} cannot be placed in TypeckResults with hir_owner {:?}", + tcx.hir().node_to_string(hir_id), + hir_id.owner, + hir_owner + ) + }); + } +} + +impl<'a, V> LocalTableInContext<'a, V> { + pub fn contains_key(&self, id: hir::HirId) -> bool { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.data.contains_key(&id.local_id) + } + + pub fn get(&self, id: hir::HirId) -> Option<&V> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.data.get(&id.local_id) + } + + pub fn iter(&self) -> hash_map::Iter<'_, hir::ItemLocalId, V> { + self.data.iter() + } +} + +impl<'a, V> ::std::ops::Index<hir::HirId> for LocalTableInContext<'a, V> { + type Output = V; + + fn index(&self, key: hir::HirId) -> &V { + self.get(key).expect("LocalTableInContext: key not found") + } +} + +pub struct LocalTableInContextMut<'a, V> { + hir_owner: LocalDefId, + data: &'a mut ItemLocalMap<V>, +} + +impl<'a, V> LocalTableInContextMut<'a, V> { + pub fn get_mut(&mut self, id: hir::HirId) -> Option<&mut V> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.data.get_mut(&id.local_id) + } + + pub fn entry(&mut self, id: hir::HirId) -> Entry<'_, hir::ItemLocalId, V> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.data.entry(id.local_id) + } + + pub fn insert(&mut self, id: hir::HirId, val: V) -> Option<V> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.data.insert(id.local_id, val) + } + + pub fn remove(&mut self, id: hir::HirId) -> Option<V> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.data.remove(&id.local_id) + } +} + +/// All information necessary to validate and reveal an `impl Trait`. +#[derive(TyEncodable, TyDecodable, Debug, HashStable)] +pub struct ResolvedOpaqueTy<'tcx> { + /// The revealed type as seen by this function. + pub concrete_type: Ty<'tcx>, + /// Generic parameters on the opaque type as passed by this function. + /// For `type Foo<A, B> = impl Bar<A, B>; fn foo<T, U>() -> Foo<T, U> { .. }` + /// this is `[T, U]`, not `[A, B]`. + pub substs: SubstsRef<'tcx>, +} + +/// Whenever a value may be live across a generator yield, the type of that value winds up in the +/// `GeneratorInteriorTypeCause` struct. This struct adds additional information about such +/// captured types that can be useful for diagnostics. In particular, it stores the span that +/// caused a given type to be recorded, along with the scope that enclosed the value (which can +/// be used to find the await that the value is live across). +/// +/// For example: +/// +/// ```ignore (pseudo-Rust) +/// async move { +/// let x: T = expr; +/// foo.await +/// ... +/// } +/// ``` +/// +/// Here, we would store the type `T`, the span of the value `x`, the "scope-span" for +/// the scope that contains `x`, the expr `T` evaluated from, and the span of `foo.await`. +#[derive(TyEncodable, TyDecodable, Clone, Debug, Eq, Hash, PartialEq, HashStable)] +pub struct GeneratorInteriorTypeCause<'tcx> { + /// Type of the captured binding. + pub ty: Ty<'tcx>, + /// Span of the binding that was captured. + pub span: Span, + /// Span of the scope of the captured binding. + pub scope_span: Option<Span>, + /// Span of `.await` or `yield` expression. + pub yield_span: Span, + /// Expr which the type evaluated from. + pub expr: Option<hir::HirId>, +} + +#[derive(TyEncodable, TyDecodable, Debug)] +pub struct TypeckResults<'tcx> { + /// The `HirId::owner` all `ItemLocalId`s in this table are relative to. + pub hir_owner: LocalDefId, + + /// Resolved definitions for `<T>::X` associated paths and + /// method calls, including those of overloaded operators. + type_dependent_defs: ItemLocalMap<Result<(DefKind, DefId), ErrorReported>>, + + /// Resolved field indices for field accesses in expressions (`S { field }`, `obj.field`) + /// or patterns (`S { field }`). The index is often useful by itself, but to learn more + /// about the field you also need definition of the variant to which the field + /// belongs, but it may not exist if it's a tuple field (`tuple.0`). + field_indices: ItemLocalMap<usize>, + + /// Stores the types for various nodes in the AST. Note that this table + /// is not guaranteed to be populated until after typeck. See + /// typeck::check::fn_ctxt for details. + node_types: ItemLocalMap<Ty<'tcx>>, + + /// Stores the type parameters which were substituted to obtain the type + /// of this node. This only applies to nodes that refer to entities + /// parameterized by type parameters, such as generic fns, types, or + /// other items. + node_substs: ItemLocalMap<SubstsRef<'tcx>>, + + /// This will either store the canonicalized types provided by the user + /// or the substitutions that the user explicitly gave (if any) attached + /// to `id`. These will not include any inferred values. The canonical form + /// is used to capture things like `_` or other unspecified values. + /// + /// For example, if the user wrote `foo.collect::<Vec<_>>()`, then the + /// canonical substitutions would include only `for<X> { Vec<X> }`. + /// + /// See also `AscribeUserType` statement in MIR. + user_provided_types: ItemLocalMap<CanonicalUserType<'tcx>>, + + /// Stores the canonicalized types provided by the user. See also + /// `AscribeUserType` statement in MIR. + pub user_provided_sigs: DefIdMap<CanonicalPolyFnSig<'tcx>>, + + adjustments: ItemLocalMap<Vec<ty::adjustment::Adjustment<'tcx>>>, + + /// Stores the actual binding mode for all instances of hir::BindingAnnotation. + pat_binding_modes: ItemLocalMap<BindingMode>, + + /// Stores the types which were implicitly dereferenced in pattern binding modes + /// for later usage in THIR lowering. For example, + /// + /// ``` + /// match &&Some(5i32) { + /// Some(n) => {}, + /// _ => {}, + /// } + /// ``` + /// leads to a `vec![&&Option<i32>, &Option<i32>]`. Empty vectors are not stored. + /// + /// See: + /// https://github.com/rust-lang/rfcs/blob/master/text/2005-match-ergonomics.md#definitions + pat_adjustments: ItemLocalMap<Vec<Ty<'tcx>>>, + + /// Borrows + pub upvar_capture_map: ty::UpvarCaptureMap<'tcx>, + + /// Records the reasons that we picked the kind of each closure; + /// not all closures are present in the map. + closure_kind_origins: ItemLocalMap<(Span, Symbol)>, + + /// For each fn, records the "liberated" types of its arguments + /// and return type. Liberated means that all bound regions + /// (including late-bound regions) are replaced with free + /// equivalents. This table is not used in codegen (since regions + /// are erased there) and hence is not serialized to metadata. + liberated_fn_sigs: ItemLocalMap<ty::FnSig<'tcx>>, + + /// For each FRU expression, record the normalized types of the fields + /// of the struct - this is needed because it is non-trivial to + /// normalize while preserving regions. This table is used only in + /// MIR construction and hence is not serialized to metadata. + fru_field_types: ItemLocalMap<Vec<Ty<'tcx>>>, + + /// For every coercion cast we add the HIR node ID of the cast + /// expression to this set. + coercion_casts: ItemLocalSet, + + /// Set of trait imports actually used in the method resolution. + /// This is used for warning unused imports. During type + /// checking, this `Lrc` should not be cloned: it must have a ref-count + /// of 1 so that we can insert things into the set mutably. + pub used_trait_imports: Lrc<FxHashSet<LocalDefId>>, + + /// If any errors occurred while type-checking this body, + /// this field will be set to `Some(ErrorReported)`. + pub tainted_by_errors: Option<ErrorReported>, + + /// All the opaque types that are restricted to concrete types + /// by this function. + pub concrete_opaque_types: FxHashMap<DefId, ResolvedOpaqueTy<'tcx>>, + + /// Given the closure ID this map provides the list of UpvarIDs used by it. + /// The upvarID contains the HIR node ID and it also contains the full path + /// leading to the member of the struct or tuple that is used instead of the + /// entire variable. + pub closure_captures: ty::UpvarListMap, + + /// Stores the type, expression, span and optional scope span of all types + /// that are live across the yield of this generator (if a generator). + pub generator_interior_types: Vec<GeneratorInteriorTypeCause<'tcx>>, +} + +impl<'tcx> TypeckResults<'tcx> { + pub fn new(hir_owner: LocalDefId) -> TypeckResults<'tcx> { + TypeckResults { + hir_owner, + type_dependent_defs: Default::default(), + field_indices: Default::default(), + user_provided_types: Default::default(), + user_provided_sigs: Default::default(), + node_types: Default::default(), + node_substs: Default::default(), + adjustments: Default::default(), + pat_binding_modes: Default::default(), + pat_adjustments: Default::default(), + upvar_capture_map: Default::default(), + closure_kind_origins: Default::default(), + liberated_fn_sigs: Default::default(), + fru_field_types: Default::default(), + coercion_casts: Default::default(), + used_trait_imports: Lrc::new(Default::default()), + tainted_by_errors: None, + concrete_opaque_types: Default::default(), + closure_captures: Default::default(), + generator_interior_types: Default::default(), + } + } + + /// Returns the final resolution of a `QPath` in an `Expr` or `Pat` node. + pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res { + match *qpath { + hir::QPath::Resolved(_, ref path) => path.res, + hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self + .type_dependent_def(id) + .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)), + } + } + + pub fn type_dependent_defs( + &self, + ) -> LocalTableInContext<'_, Result<(DefKind, DefId), ErrorReported>> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.type_dependent_defs } + } + + pub fn type_dependent_def(&self, id: HirId) -> Option<(DefKind, DefId)> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.type_dependent_defs.get(&id.local_id).cloned().and_then(|r| r.ok()) + } + + pub fn type_dependent_def_id(&self, id: HirId) -> Option<DefId> { + self.type_dependent_def(id).map(|(_, def_id)| def_id) + } + + pub fn type_dependent_defs_mut( + &mut self, + ) -> LocalTableInContextMut<'_, Result<(DefKind, DefId), ErrorReported>> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.type_dependent_defs } + } + + pub fn field_indices(&self) -> LocalTableInContext<'_, usize> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.field_indices } + } + + pub fn field_indices_mut(&mut self) -> LocalTableInContextMut<'_, usize> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.field_indices } + } + + pub fn user_provided_types(&self) -> LocalTableInContext<'_, CanonicalUserType<'tcx>> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.user_provided_types } + } + + pub fn user_provided_types_mut( + &mut self, + ) -> LocalTableInContextMut<'_, CanonicalUserType<'tcx>> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.user_provided_types } + } + + pub fn node_types(&self) -> LocalTableInContext<'_, Ty<'tcx>> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.node_types } + } + + pub fn node_types_mut(&mut self) -> LocalTableInContextMut<'_, Ty<'tcx>> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.node_types } + } + + pub fn node_type(&self, id: hir::HirId) -> Ty<'tcx> { + self.node_type_opt(id).unwrap_or_else(|| { + bug!("node_type: no type for node `{}`", tls::with(|tcx| tcx.hir().node_to_string(id))) + }) + } + + pub fn node_type_opt(&self, id: hir::HirId) -> Option<Ty<'tcx>> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.node_types.get(&id.local_id).cloned() + } + + pub fn node_substs_mut(&mut self) -> LocalTableInContextMut<'_, SubstsRef<'tcx>> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.node_substs } + } + + pub fn node_substs(&self, id: hir::HirId) -> SubstsRef<'tcx> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.node_substs.get(&id.local_id).cloned().unwrap_or_else(|| InternalSubsts::empty()) + } + + pub fn node_substs_opt(&self, id: hir::HirId) -> Option<SubstsRef<'tcx>> { + validate_hir_id_for_typeck_results(self.hir_owner, id); + self.node_substs.get(&id.local_id).cloned() + } + + // Returns the type of a pattern as a monotype. Like @expr_ty, this function + // doesn't provide type parameter substitutions. + pub fn pat_ty(&self, pat: &hir::Pat<'_>) -> Ty<'tcx> { + self.node_type(pat.hir_id) + } + + pub fn pat_ty_opt(&self, pat: &hir::Pat<'_>) -> Option<Ty<'tcx>> { + self.node_type_opt(pat.hir_id) + } + + // Returns the type of an expression as a monotype. + // + // NB (1): This is the PRE-ADJUSTMENT TYPE for the expression. That is, in + // some cases, we insert `Adjustment` annotations such as auto-deref or + // auto-ref. The type returned by this function does not consider such + // adjustments. See `expr_ty_adjusted()` instead. + // + // NB (2): This type doesn't provide type parameter substitutions; e.g., if you + // ask for the type of "id" in "id(3)", it will return "fn(&isize) -> isize" + // instead of "fn(ty) -> T with T = isize". + pub fn expr_ty(&self, expr: &hir::Expr<'_>) -> Ty<'tcx> { + self.node_type(expr.hir_id) + } + + pub fn expr_ty_opt(&self, expr: &hir::Expr<'_>) -> Option<Ty<'tcx>> { + self.node_type_opt(expr.hir_id) + } + + pub fn adjustments(&self) -> LocalTableInContext<'_, Vec<ty::adjustment::Adjustment<'tcx>>> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.adjustments } + } + + pub fn adjustments_mut( + &mut self, + ) -> LocalTableInContextMut<'_, Vec<ty::adjustment::Adjustment<'tcx>>> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.adjustments } + } + + pub fn expr_adjustments(&self, expr: &hir::Expr<'_>) -> &[ty::adjustment::Adjustment<'tcx>] { + validate_hir_id_for_typeck_results(self.hir_owner, expr.hir_id); + self.adjustments.get(&expr.hir_id.local_id).map_or(&[], |a| &a[..]) + } + + /// Returns the type of `expr`, considering any `Adjustment` + /// entry recorded for that expression. + pub fn expr_ty_adjusted(&self, expr: &hir::Expr<'_>) -> Ty<'tcx> { + self.expr_adjustments(expr).last().map_or_else(|| self.expr_ty(expr), |adj| adj.target) + } + + pub fn expr_ty_adjusted_opt(&self, expr: &hir::Expr<'_>) -> Option<Ty<'tcx>> { + self.expr_adjustments(expr).last().map(|adj| adj.target).or_else(|| self.expr_ty_opt(expr)) + } + + pub fn is_method_call(&self, expr: &hir::Expr<'_>) -> bool { + // Only paths and method calls/overloaded operators have + // entries in type_dependent_defs, ignore the former here. + if let hir::ExprKind::Path(_) = expr.kind { + return false; + } + + match self.type_dependent_defs().get(expr.hir_id) { + Some(Ok((DefKind::AssocFn, _))) => true, + _ => false, + } + } + + pub fn extract_binding_mode(&self, s: &Session, id: HirId, sp: Span) -> Option<BindingMode> { + self.pat_binding_modes().get(id).copied().or_else(|| { + s.delay_span_bug(sp, "missing binding mode"); + None + }) + } + + pub fn pat_binding_modes(&self) -> LocalTableInContext<'_, BindingMode> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.pat_binding_modes } + } + + pub fn pat_binding_modes_mut(&mut self) -> LocalTableInContextMut<'_, BindingMode> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.pat_binding_modes } + } + + pub fn pat_adjustments(&self) -> LocalTableInContext<'_, Vec<Ty<'tcx>>> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.pat_adjustments } + } + + pub fn pat_adjustments_mut(&mut self) -> LocalTableInContextMut<'_, Vec<Ty<'tcx>>> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.pat_adjustments } + } + + pub fn upvar_capture(&self, upvar_id: ty::UpvarId) -> ty::UpvarCapture<'tcx> { + self.upvar_capture_map[&upvar_id] + } + + pub fn closure_kind_origins(&self) -> LocalTableInContext<'_, (Span, Symbol)> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.closure_kind_origins } + } + + pub fn closure_kind_origins_mut(&mut self) -> LocalTableInContextMut<'_, (Span, Symbol)> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.closure_kind_origins } + } + + pub fn liberated_fn_sigs(&self) -> LocalTableInContext<'_, ty::FnSig<'tcx>> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.liberated_fn_sigs } + } + + pub fn liberated_fn_sigs_mut(&mut self) -> LocalTableInContextMut<'_, ty::FnSig<'tcx>> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.liberated_fn_sigs } + } + + pub fn fru_field_types(&self) -> LocalTableInContext<'_, Vec<Ty<'tcx>>> { + LocalTableInContext { hir_owner: self.hir_owner, data: &self.fru_field_types } + } + + pub fn fru_field_types_mut(&mut self) -> LocalTableInContextMut<'_, Vec<Ty<'tcx>>> { + LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.fru_field_types } + } + + pub fn is_coercion_cast(&self, hir_id: hir::HirId) -> bool { + validate_hir_id_for_typeck_results(self.hir_owner, hir_id); + self.coercion_casts.contains(&hir_id.local_id) + } + + pub fn set_coercion_cast(&mut self, id: ItemLocalId) { + self.coercion_casts.insert(id); + } + + pub fn coercion_casts(&self) -> &ItemLocalSet { + &self.coercion_casts + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TypeckResults<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let ty::TypeckResults { + hir_owner, + ref type_dependent_defs, + ref field_indices, + ref user_provided_types, + ref user_provided_sigs, + ref node_types, + ref node_substs, + ref adjustments, + ref pat_binding_modes, + ref pat_adjustments, + ref upvar_capture_map, + ref closure_kind_origins, + ref liberated_fn_sigs, + ref fru_field_types, + + ref coercion_casts, + + ref used_trait_imports, + tainted_by_errors, + ref concrete_opaque_types, + ref closure_captures, + ref generator_interior_types, + } = *self; + + hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { + type_dependent_defs.hash_stable(hcx, hasher); + field_indices.hash_stable(hcx, hasher); + user_provided_types.hash_stable(hcx, hasher); + user_provided_sigs.hash_stable(hcx, hasher); + node_types.hash_stable(hcx, hasher); + node_substs.hash_stable(hcx, hasher); + adjustments.hash_stable(hcx, hasher); + pat_binding_modes.hash_stable(hcx, hasher); + pat_adjustments.hash_stable(hcx, hasher); + hash_stable_hashmap(hcx, hasher, upvar_capture_map, |up_var_id, hcx| { + let ty::UpvarId { var_path, closure_expr_id } = *up_var_id; + + assert_eq!(var_path.hir_id.owner, hir_owner); + + ( + hcx.local_def_path_hash(var_path.hir_id.owner), + var_path.hir_id.local_id, + hcx.local_def_path_hash(closure_expr_id), + ) + }); + + closure_kind_origins.hash_stable(hcx, hasher); + liberated_fn_sigs.hash_stable(hcx, hasher); + fru_field_types.hash_stable(hcx, hasher); + coercion_casts.hash_stable(hcx, hasher); + used_trait_imports.hash_stable(hcx, hasher); + tainted_by_errors.hash_stable(hcx, hasher); + concrete_opaque_types.hash_stable(hcx, hasher); + closure_captures.hash_stable(hcx, hasher); + generator_interior_types.hash_stable(hcx, hasher); + }) + } +} + +rustc_index::newtype_index! { + pub struct UserTypeAnnotationIndex { + derive [HashStable] + DEBUG_FORMAT = "UserType({})", + const START_INDEX = 0, + } +} + +/// Mapping of type annotation indices to canonical user type annotations. +pub type CanonicalUserTypeAnnotations<'tcx> = + IndexVec<UserTypeAnnotationIndex, CanonicalUserTypeAnnotation<'tcx>>; + +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, Lift)] +pub struct CanonicalUserTypeAnnotation<'tcx> { + pub user_ty: CanonicalUserType<'tcx>, + pub span: Span, + pub inferred_ty: Ty<'tcx>, +} + +/// Canonicalized user type annotation. +pub type CanonicalUserType<'tcx> = Canonical<'tcx, UserType<'tcx>>; + +impl CanonicalUserType<'tcx> { + /// Returns `true` if this represents a substitution of the form `[?0, ?1, ?2]`, + /// i.e., each thing is mapped to a canonical variable with the same index. + pub fn is_identity(&self) -> bool { + match self.value { + UserType::Ty(_) => false, + UserType::TypeOf(_, user_substs) => { + if user_substs.user_self_ty.is_some() { + return false; + } + + user_substs.substs.iter().zip(BoundVar::new(0)..).all(|(kind, cvar)| { + match kind.unpack() { + GenericArgKind::Type(ty) => match ty.kind { + ty::Bound(debruijn, b) => { + // We only allow a `ty::INNERMOST` index in substitutions. + assert_eq!(debruijn, ty::INNERMOST); + cvar == b.var + } + _ => false, + }, + + GenericArgKind::Lifetime(r) => match r { + ty::ReLateBound(debruijn, br) => { + // We only allow a `ty::INNERMOST` index in substitutions. + assert_eq!(*debruijn, ty::INNERMOST); + cvar == br.assert_bound_var() + } + _ => false, + }, + + GenericArgKind::Const(ct) => match ct.val { + ty::ConstKind::Bound(debruijn, b) => { + // We only allow a `ty::INNERMOST` index in substitutions. + assert_eq!(debruijn, ty::INNERMOST); + cvar == b + } + _ => false, + }, + } + }) + } + } + } +} + +/// A user-given type annotation attached to a constant. These arise +/// from constants that are named via paths, like `Foo::<A>::new` and +/// so forth. +#[derive(Copy, Clone, Debug, PartialEq, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable, Lift)] +pub enum UserType<'tcx> { + Ty(Ty<'tcx>), + + /// The canonical type is the result of `type_of(def_id)` with the + /// given substitutions applied. + TypeOf(DefId, UserSubsts<'tcx>), +} + +impl<'tcx> CommonTypes<'tcx> { + fn new(interners: &CtxtInterners<'tcx>) -> CommonTypes<'tcx> { + let mk = |ty| interners.intern_ty(ty); + + CommonTypes { + unit: mk(Tuple(List::empty())), + bool: mk(Bool), + char: mk(Char), + never: mk(Never), + isize: mk(Int(ast::IntTy::Isize)), + i8: mk(Int(ast::IntTy::I8)), + i16: mk(Int(ast::IntTy::I16)), + i32: mk(Int(ast::IntTy::I32)), + i64: mk(Int(ast::IntTy::I64)), + i128: mk(Int(ast::IntTy::I128)), + usize: mk(Uint(ast::UintTy::Usize)), + u8: mk(Uint(ast::UintTy::U8)), + u16: mk(Uint(ast::UintTy::U16)), + u32: mk(Uint(ast::UintTy::U32)), + u64: mk(Uint(ast::UintTy::U64)), + u128: mk(Uint(ast::UintTy::U128)), + f32: mk(Float(ast::FloatTy::F32)), + f64: mk(Float(ast::FloatTy::F64)), + str_: mk(Str), + self_param: mk(ty::Param(ty::ParamTy { index: 0, name: kw::SelfUpper })), + + trait_object_dummy_self: mk(Infer(ty::FreshTy(0))), + } + } +} + +impl<'tcx> CommonLifetimes<'tcx> { + fn new(interners: &CtxtInterners<'tcx>) -> CommonLifetimes<'tcx> { + let mk = |r| interners.region.intern(r, |r| Interned(interners.arena.alloc(r))).0; + + CommonLifetimes { + re_root_empty: mk(RegionKind::ReEmpty(ty::UniverseIndex::ROOT)), + re_static: mk(RegionKind::ReStatic), + re_erased: mk(RegionKind::ReErased), + } + } +} + +impl<'tcx> CommonConsts<'tcx> { + fn new(interners: &CtxtInterners<'tcx>, types: &CommonTypes<'tcx>) -> CommonConsts<'tcx> { + let mk_const = |c| interners.const_.intern(c, |c| Interned(interners.arena.alloc(c))).0; + + CommonConsts { + unit: mk_const(ty::Const { + val: ty::ConstKind::Value(ConstValue::Scalar(Scalar::zst())), + ty: types.unit, + }), + } + } +} + +// This struct contains information regarding the `ReFree(FreeRegion)` corresponding to a lifetime +// conflict. +#[derive(Debug)] +pub struct FreeRegionInfo { + // `LocalDefId` corresponding to FreeRegion + pub def_id: LocalDefId, + // the bound region corresponding to FreeRegion + pub boundregion: ty::BoundRegion, + // checks if bound region is in Impl Item + pub is_impl_item: bool, +} + +/// The central data structure of the compiler. It stores references +/// to the various **arenas** and also houses the results of the +/// various **compiler queries** that have been performed. See the +/// [rustc dev guide] for more details. +/// +/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/ty.html +#[derive(Copy, Clone)] +#[rustc_diagnostic_item = "TyCtxt"] +pub struct TyCtxt<'tcx> { + gcx: &'tcx GlobalCtxt<'tcx>, +} + +impl<'tcx> Deref for TyCtxt<'tcx> { + type Target = &'tcx GlobalCtxt<'tcx>; + #[inline(always)] + fn deref(&self) -> &Self::Target { + &self.gcx + } +} + +pub struct GlobalCtxt<'tcx> { + pub arena: &'tcx WorkerLocal<Arena<'tcx>>, + + interners: CtxtInterners<'tcx>, + + pub(crate) cstore: Box<CrateStoreDyn>, + + pub sess: &'tcx Session, + + /// This only ever stores a `LintStore` but we don't want a dependency on that type here. + /// + /// FIXME(Centril): consider `dyn LintStoreMarker` once + /// we can upcast to `Any` for some additional type safety. + pub lint_store: Lrc<dyn Any + sync::Sync + sync::Send>, + + pub dep_graph: DepGraph, + + pub prof: SelfProfilerRef, + + /// Common types, pre-interned for your convenience. + pub types: CommonTypes<'tcx>, + + /// Common lifetimes, pre-interned for your convenience. + pub lifetimes: CommonLifetimes<'tcx>, + + /// Common consts, pre-interned for your convenience. + pub consts: CommonConsts<'tcx>, + + /// Resolutions of `extern crate` items produced by resolver. + extern_crate_map: FxHashMap<LocalDefId, CrateNum>, + + /// Map indicating what traits are in scope for places where this + /// is relevant; generated by resolve. + trait_map: FxHashMap<LocalDefId, FxHashMap<ItemLocalId, StableVec<TraitCandidate>>>, + + /// Export map produced by name resolution. + export_map: ExportMap<LocalDefId>, + + pub(crate) untracked_crate: &'tcx hir::Crate<'tcx>, + pub(crate) definitions: &'tcx Definitions, + + /// A map from `DefPathHash` -> `DefId`. Includes `DefId`s from the local crate + /// as well as all upstream crates. Only populated in incremental mode. + pub def_path_hash_to_def_id: Option<FxHashMap<DefPathHash, DefId>>, + + pub queries: query::Queries<'tcx>, + + maybe_unused_trait_imports: FxHashSet<LocalDefId>, + maybe_unused_extern_crates: Vec<(LocalDefId, Span)>, + /// A map of glob use to a set of names it actually imports. Currently only + /// used in save-analysis. + glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>, + /// Extern prelude entries. The value is `true` if the entry was introduced + /// via `extern crate` item and not `--extern` option or compiler built-in. + pub extern_prelude: FxHashMap<Symbol, bool>, + + // Internal caches for metadata decoding. No need to track deps on this. + pub ty_rcache: Lock<FxHashMap<ty::CReaderCacheKey, Ty<'tcx>>>, + pub pred_rcache: Lock<FxHashMap<ty::CReaderCacheKey, Predicate<'tcx>>>, + + /// Caches the results of trait selection. This cache is used + /// for things that do not have to do with the parameters in scope. + pub selection_cache: traits::SelectionCache<'tcx>, + + /// Caches the results of trait evaluation. This cache is used + /// for things that do not have to do with the parameters in scope. + /// Merge this with `selection_cache`? + pub evaluation_cache: traits::EvaluationCache<'tcx>, + + /// The definite name of the current crate after taking into account + /// attributes, commandline parameters, etc. + pub crate_name: Symbol, + + /// Data layout specification for the current target. + pub data_layout: TargetDataLayout, + + /// `#[stable]` and `#[unstable]` attributes + stability_interner: ShardedHashMap<&'tcx attr::Stability, ()>, + + /// `#[rustc_const_stable]` and `#[rustc_const_unstable]` attributes + const_stability_interner: ShardedHashMap<&'tcx attr::ConstStability, ()>, + + /// Stores the value of constants (and deduplicates the actual memory) + allocation_interner: ShardedHashMap<&'tcx Allocation, ()>, + + /// Stores memory for globals (statics/consts). + pub(crate) alloc_map: Lock<interpret::AllocMap<'tcx>>, + + layout_interner: ShardedHashMap<&'tcx Layout, ()>, + + output_filenames: Arc<OutputFilenames>, +} + +impl<'tcx> TyCtxt<'tcx> { + pub fn typeck_opt_const_arg( + self, + def: ty::WithOptConstParam<LocalDefId>, + ) -> &'tcx TypeckResults<'tcx> { + if let Some(param_did) = def.const_param_did { + self.typeck_const_arg((def.did, param_did)) + } else { + self.typeck(def.did) + } + } + + pub fn alloc_steal_mir(self, mir: Body<'tcx>) -> &'tcx Steal<Body<'tcx>> { + self.arena.alloc(Steal::new(mir)) + } + + pub fn alloc_steal_promoted( + self, + promoted: IndexVec<Promoted, Body<'tcx>>, + ) -> &'tcx Steal<IndexVec<Promoted, Body<'tcx>>> { + self.arena.alloc(Steal::new(promoted)) + } + + pub fn alloc_adt_def( + self, + did: DefId, + kind: AdtKind, + variants: IndexVec<VariantIdx, ty::VariantDef>, + repr: ReprOptions, + ) -> &'tcx ty::AdtDef { + self.arena.alloc(ty::AdtDef::new(self, did, kind, variants, repr)) + } + + pub fn intern_const_alloc(self, alloc: Allocation) -> &'tcx Allocation { + self.allocation_interner.intern(alloc, |alloc| self.arena.alloc(alloc)) + } + + /// Allocates a read-only byte or string literal for `mir::interpret`. + pub fn allocate_bytes(self, bytes: &[u8]) -> interpret::AllocId { + // Create an allocation that just contains these bytes. + let alloc = interpret::Allocation::from_byte_aligned_bytes(bytes); + let alloc = self.intern_const_alloc(alloc); + self.create_memory_alloc(alloc) + } + + pub fn intern_stability(self, stab: attr::Stability) -> &'tcx attr::Stability { + self.stability_interner.intern(stab, |stab| self.arena.alloc(stab)) + } + + pub fn intern_const_stability(self, stab: attr::ConstStability) -> &'tcx attr::ConstStability { + self.const_stability_interner.intern(stab, |stab| self.arena.alloc(stab)) + } + + pub fn intern_layout(self, layout: Layout) -> &'tcx Layout { + self.layout_interner.intern(layout, |layout| self.arena.alloc(layout)) + } + + /// Returns a range of the start/end indices specified with the + /// `rustc_layout_scalar_valid_range` attribute. + pub fn layout_scalar_valid_range(self, def_id: DefId) -> (Bound<u128>, Bound<u128>) { + let attrs = self.get_attrs(def_id); + let get = |name| { + let attr = match attrs.iter().find(|a| self.sess.check_name(a, name)) { + Some(attr) => attr, + None => return Bound::Unbounded, + }; + debug!("layout_scalar_valid_range: attr={:?}", attr); + for meta in attr.meta_item_list().expect("rustc_layout_scalar_valid_range takes args") { + match meta.literal().expect("attribute takes lit").kind { + ast::LitKind::Int(a, _) => return Bound::Included(a), + _ => span_bug!(attr.span, "rustc_layout_scalar_valid_range expects int arg"), + } + } + span_bug!(attr.span, "no arguments to `rustc_layout_scalar_valid_range` attribute"); + }; + ( + get(sym::rustc_layout_scalar_valid_range_start), + get(sym::rustc_layout_scalar_valid_range_end), + ) + } + + pub fn lift<T: ?Sized + Lift<'tcx>>(self, value: &T) -> Option<T::Lifted> { + value.lift_to_tcx(self) + } + + /// Creates a type context and call the closure with a `TyCtxt` reference + /// to the context. The closure enforces that the type context and any interned + /// value (types, substs, etc.) can only be used while `ty::tls` has a valid + /// reference to the context, to allow formatting values that need it. + pub fn create_global_ctxt( + s: &'tcx Session, + lint_store: Lrc<dyn Any + sync::Send + sync::Sync>, + local_providers: ty::query::Providers, + extern_providers: ty::query::Providers, + arena: &'tcx WorkerLocal<Arena<'tcx>>, + resolutions: ty::ResolverOutputs, + krate: &'tcx hir::Crate<'tcx>, + definitions: &'tcx Definitions, + dep_graph: DepGraph, + on_disk_query_result_cache: query::OnDiskCache<'tcx>, + crate_name: &str, + output_filenames: &OutputFilenames, + ) -> GlobalCtxt<'tcx> { + let data_layout = TargetDataLayout::parse(&s.target.target).unwrap_or_else(|err| { + s.fatal(&err); + }); + let interners = CtxtInterners::new(arena); + let common_types = CommonTypes::new(&interners); + let common_lifetimes = CommonLifetimes::new(&interners); + let common_consts = CommonConsts::new(&interners, &common_types); + let cstore = resolutions.cstore; + let crates = cstore.crates_untracked(); + let max_cnum = crates.iter().map(|c| c.as_usize()).max().unwrap_or(0); + let mut providers = IndexVec::from_elem_n(extern_providers, max_cnum + 1); + providers[LOCAL_CRATE] = local_providers; + + let def_path_hash_to_def_id = if s.opts.build_dep_graph() { + let capacity = definitions.def_path_table().num_def_ids() + + crates.iter().map(|cnum| cstore.num_def_ids(*cnum)).sum::<usize>(); + let mut map = FxHashMap::with_capacity_and_hasher(capacity, Default::default()); + + map.extend(definitions.def_path_table().all_def_path_hashes_and_def_ids(LOCAL_CRATE)); + for cnum in &crates { + map.extend(cstore.all_def_path_hashes_and_def_ids(*cnum).into_iter()); + } + + Some(map) + } else { + None + }; + + let mut trait_map: FxHashMap<_, FxHashMap<_, _>> = FxHashMap::default(); + for (hir_id, v) in krate.trait_map.iter() { + let map = trait_map.entry(hir_id.owner).or_default(); + map.insert(hir_id.local_id, StableVec::new(v.to_vec())); + } + + GlobalCtxt { + sess: s, + lint_store, + cstore, + arena, + interners, + dep_graph, + prof: s.prof.clone(), + types: common_types, + lifetimes: common_lifetimes, + consts: common_consts, + extern_crate_map: resolutions.extern_crate_map, + trait_map, + export_map: resolutions.export_map, + maybe_unused_trait_imports: resolutions.maybe_unused_trait_imports, + maybe_unused_extern_crates: resolutions.maybe_unused_extern_crates, + glob_map: resolutions.glob_map, + extern_prelude: resolutions.extern_prelude, + untracked_crate: krate, + definitions, + def_path_hash_to_def_id, + queries: query::Queries::new(providers, extern_providers, on_disk_query_result_cache), + ty_rcache: Default::default(), + pred_rcache: Default::default(), + selection_cache: Default::default(), + evaluation_cache: Default::default(), + crate_name: Symbol::intern(crate_name), + data_layout, + layout_interner: Default::default(), + stability_interner: Default::default(), + const_stability_interner: Default::default(), + allocation_interner: Default::default(), + alloc_map: Lock::new(interpret::AllocMap::new()), + output_filenames: Arc::new(output_filenames.clone()), + } + } + + /// Constructs a `TyKind::Error` type and registers a `delay_span_bug` to ensure it gets used. + #[track_caller] + pub fn ty_error(self) -> Ty<'tcx> { + self.ty_error_with_message(DUMMY_SP, "TyKind::Error constructed but no error reported") + } + + /// Constructs a `TyKind::Error` type and registers a `delay_span_bug` with the given `msg` to + /// ensure it gets used. + #[track_caller] + pub fn ty_error_with_message<S: Into<MultiSpan>>(self, span: S, msg: &str) -> Ty<'tcx> { + self.sess.delay_span_bug(span, msg); + self.mk_ty(Error(DelaySpanBugEmitted(()))) + } + + /// Like `err` but for constants. + #[track_caller] + pub fn const_error(self, ty: Ty<'tcx>) -> &'tcx Const<'tcx> { + self.sess + .delay_span_bug(DUMMY_SP, "ty::ConstKind::Error constructed but no error reported."); + self.mk_const(ty::Const { val: ty::ConstKind::Error(DelaySpanBugEmitted(())), ty }) + } + + pub fn consider_optimizing<T: Fn() -> String>(&self, msg: T) -> bool { + let cname = self.crate_name(LOCAL_CRATE).as_str(); + self.sess.consider_optimizing(&cname, msg) + } + + pub fn lib_features(self) -> &'tcx middle::lib_features::LibFeatures { + self.get_lib_features(LOCAL_CRATE) + } + + /// Obtain all lang items of this crate and all dependencies (recursively) + pub fn lang_items(self) -> &'tcx rustc_hir::lang_items::LanguageItems { + self.get_lang_items(LOCAL_CRATE) + } + + /// Obtain the given diagnostic item's `DefId`. Use `is_diagnostic_item` if you just want to + /// compare against another `DefId`, since `is_diagnostic_item` is cheaper. + pub fn get_diagnostic_item(self, name: Symbol) -> Option<DefId> { + self.all_diagnostic_items(LOCAL_CRATE).get(&name).copied() + } + + /// Check whether the diagnostic item with the given `name` has the given `DefId`. + pub fn is_diagnostic_item(self, name: Symbol, did: DefId) -> bool { + self.diagnostic_items(did.krate).get(&name) == Some(&did) + } + + pub fn stability(self) -> &'tcx stability::Index<'tcx> { + self.stability_index(LOCAL_CRATE) + } + + pub fn crates(self) -> &'tcx [CrateNum] { + self.all_crate_nums(LOCAL_CRATE) + } + + pub fn allocator_kind(self) -> Option<AllocatorKind> { + self.cstore.allocator_kind() + } + + pub fn features(self) -> &'tcx rustc_feature::Features { + self.features_query(LOCAL_CRATE) + } + + pub fn def_key(self, id: DefId) -> rustc_hir::definitions::DefKey { + if let Some(id) = id.as_local() { self.hir().def_key(id) } else { self.cstore.def_key(id) } + } + + /// Converts a `DefId` into its fully expanded `DefPath` (every + /// `DefId` is really just an interned `DefPath`). + /// + /// Note that if `id` is not local to this crate, the result will + /// be a non-local `DefPath`. + pub fn def_path(self, id: DefId) -> rustc_hir::definitions::DefPath { + if let Some(id) = id.as_local() { + self.hir().def_path(id) + } else { + self.cstore.def_path(id) + } + } + + /// Returns whether or not the crate with CrateNum 'cnum' + /// is marked as a private dependency + pub fn is_private_dep(self, cnum: CrateNum) -> bool { + if cnum == LOCAL_CRATE { false } else { self.cstore.crate_is_private_dep_untracked(cnum) } + } + + #[inline] + pub fn def_path_hash(self, def_id: DefId) -> rustc_hir::definitions::DefPathHash { + if let Some(def_id) = def_id.as_local() { + self.definitions.def_path_hash(def_id) + } else { + self.cstore.def_path_hash(def_id) + } + } + + pub fn def_path_debug_str(self, def_id: DefId) -> String { + // We are explicitly not going through queries here in order to get + // crate name and disambiguator since this code is called from debug!() + // statements within the query system and we'd run into endless + // recursion otherwise. + let (crate_name, crate_disambiguator) = if def_id.is_local() { + (self.crate_name, self.sess.local_crate_disambiguator()) + } else { + ( + self.cstore.crate_name_untracked(def_id.krate), + self.cstore.crate_disambiguator_untracked(def_id.krate), + ) + }; + + format!( + "{}[{}]{}", + crate_name, + // Don't print the whole crate disambiguator. That's just + // annoying in debug output. + &(crate_disambiguator.to_fingerprint().to_hex())[..4], + self.def_path(def_id).to_string_no_crate() + ) + } + + pub fn metadata_encoding_version(self) -> Vec<u8> { + self.cstore.metadata_encoding_version().to_vec() + } + + pub fn encode_metadata(self) -> EncodedMetadata { + let _prof_timer = self.prof.verbose_generic_activity("generate_crate_metadata"); + self.cstore.encode_metadata(self) + } + + // Note that this is *untracked* and should only be used within the query + // system if the result is otherwise tracked through queries + pub fn cstore_as_any(self) -> &'tcx dyn Any { + self.cstore.as_any() + } + + #[inline(always)] + pub fn create_stable_hashing_context(self) -> StableHashingContext<'tcx> { + let krate = self.gcx.untracked_crate; + + StableHashingContext::new(self.sess, krate, self.definitions, &*self.cstore) + } + + #[inline(always)] + pub fn create_no_span_stable_hashing_context(self) -> StableHashingContext<'tcx> { + let krate = self.gcx.untracked_crate; + + StableHashingContext::ignore_spans(self.sess, krate, self.definitions, &*self.cstore) + } + + // This method makes sure that we have a DepNode and a Fingerprint for + // every upstream crate. It needs to be called once right after the tcx is + // created. + // With full-fledged red/green, the method will probably become unnecessary + // as this will be done on-demand. + pub fn allocate_metadata_dep_nodes(self) { + // We cannot use the query versions of crates() and crate_hash(), since + // those would need the DepNodes that we are allocating here. + for cnum in self.cstore.crates_untracked() { + let dep_node = DepConstructor::CrateMetadata(self, cnum); + let crate_hash = self.cstore.crate_hash_untracked(cnum); + self.dep_graph.with_task( + dep_node, + self, + crate_hash, + |_, x| x, // No transformation needed + dep_graph::hash_result, + ); + } + } + + pub fn serialize_query_result_cache<E>(self, encoder: &mut E) -> Result<(), E::Error> + where + E: ty::codec::OpaqueEncoder, + { + self.queries.on_disk_cache.serialize(self, encoder) + } + + /// If `true`, we should use the MIR-based borrowck, but also + /// fall back on the AST borrowck if the MIR-based one errors. + pub fn migrate_borrowck(self) -> bool { + self.borrowck_mode().migrate() + } + + /// What mode(s) of borrowck should we run? AST? MIR? both? + /// (Also considers the `#![feature(nll)]` setting.) + pub fn borrowck_mode(self) -> BorrowckMode { + // Here are the main constraints we need to deal with: + // + // 1. An opts.borrowck_mode of `BorrowckMode::Migrate` is + // synonymous with no `-Z borrowck=...` flag at all. + // + // 2. We want to allow developers on the Nightly channel + // to opt back into the "hard error" mode for NLL, + // (which they can do via specifying `#![feature(nll)]` + // explicitly in their crate). + // + // So, this precedence list is how pnkfelix chose to work with + // the above constraints: + // + // * `#![feature(nll)]` *always* means use NLL with hard + // errors. (To simplify the code here, it now even overrides + // a user's attempt to specify `-Z borrowck=compare`, which + // we arguably do not need anymore and should remove.) + // + // * Otherwise, if no `-Z borrowck=...` then use migrate mode + // + // * Otherwise, use the behavior requested via `-Z borrowck=...` + + if self.features().nll { + return BorrowckMode::Mir; + } + + self.sess.opts.borrowck_mode + } + + /// If `true`, we should use lazy normalization for constants, otherwise + /// we still evaluate them eagerly. + #[inline] + pub fn lazy_normalization(self) -> bool { + let features = self.features(); + // Note: We do not enable lazy normalization for `features.min_const_generics`. + features.const_generics || features.lazy_normalization_consts + } + + #[inline] + pub fn local_crate_exports_generics(self) -> bool { + debug_assert!(self.sess.opts.share_generics()); + + self.sess.crate_types().iter().any(|crate_type| { + match crate_type { + CrateType::Executable + | CrateType::Staticlib + | CrateType::ProcMacro + | CrateType::Cdylib => false, + + // FIXME rust-lang/rust#64319, rust-lang/rust#64872: + // We want to block export of generics from dylibs, + // but we must fix rust-lang/rust#65890 before we can + // do that robustly. + CrateType::Dylib => true, + + CrateType::Rlib => true, + } + }) + } + + // Returns the `DefId` and the `BoundRegion` corresponding to the given region. + pub fn is_suitable_region(&self, region: Region<'tcx>) -> Option<FreeRegionInfo> { + let (suitable_region_binding_scope, bound_region) = match *region { + ty::ReFree(ref free_region) => { + (free_region.scope.expect_local(), free_region.bound_region) + } + ty::ReEarlyBound(ref ebr) => ( + self.parent(ebr.def_id).unwrap().expect_local(), + ty::BoundRegion::BrNamed(ebr.def_id, ebr.name), + ), + _ => return None, // not a free region + }; + + let hir_id = self.hir().local_def_id_to_hir_id(suitable_region_binding_scope); + let is_impl_item = match self.hir().find(hir_id) { + Some(Node::Item(..) | Node::TraitItem(..)) => false, + Some(Node::ImplItem(..)) => { + self.is_bound_region_in_impl_item(suitable_region_binding_scope) + } + _ => return None, + }; + + Some(FreeRegionInfo { + def_id: suitable_region_binding_scope, + boundregion: bound_region, + is_impl_item, + }) + } + + /// Given a `DefId` for an `fn`, return all the `dyn` and `impl` traits in its return type. + pub fn return_type_impl_or_dyn_traits( + &self, + scope_def_id: LocalDefId, + ) -> Vec<&'tcx hir::Ty<'tcx>> { + let hir_id = self.hir().local_def_id_to_hir_id(scope_def_id); + let hir_output = match self.hir().get(hir_id) { + Node::Item(hir::Item { + kind: + ItemKind::Fn( + hir::FnSig { + decl: hir::FnDecl { output: hir::FnRetTy::Return(ty), .. }, + .. + }, + .., + ), + .. + }) + | Node::ImplItem(hir::ImplItem { + kind: + hir::ImplItemKind::Fn( + hir::FnSig { + decl: hir::FnDecl { output: hir::FnRetTy::Return(ty), .. }, + .. + }, + _, + ), + .. + }) + | Node::TraitItem(hir::TraitItem { + kind: + hir::TraitItemKind::Fn( + hir::FnSig { + decl: hir::FnDecl { output: hir::FnRetTy::Return(ty), .. }, + .. + }, + _, + ), + .. + }) => ty, + _ => return vec![], + }; + + let mut v = TraitObjectVisitor(vec![], self.hir()); + v.visit_ty(hir_output); + v.0 + } + + pub fn return_type_impl_trait(&self, scope_def_id: LocalDefId) -> Option<(Ty<'tcx>, Span)> { + // HACK: `type_of_def_id()` will fail on these (#55796), so return `None`. + let hir_id = self.hir().local_def_id_to_hir_id(scope_def_id); + match self.hir().get(hir_id) { + Node::Item(item) => { + match item.kind { + ItemKind::Fn(..) => { /* `type_of_def_id()` will work */ } + _ => { + return None; + } + } + } + _ => { /* `type_of_def_id()` will work or panic */ } + } + + let ret_ty = self.type_of(scope_def_id); + match ret_ty.kind { + ty::FnDef(_, _) => { + let sig = ret_ty.fn_sig(*self); + let output = self.erase_late_bound_regions(&sig.output()); + if output.is_impl_trait() { + let fn_decl = self.hir().fn_decl_by_hir_id(hir_id).unwrap(); + Some((output, fn_decl.output.span())) + } else { + None + } + } + _ => None, + } + } + + // Checks if the bound region is in Impl Item. + pub fn is_bound_region_in_impl_item(&self, suitable_region_binding_scope: LocalDefId) -> bool { + let container_id = + self.associated_item(suitable_region_binding_scope.to_def_id()).container.id(); + if self.impl_trait_ref(container_id).is_some() { + // For now, we do not try to target impls of traits. This is + // because this message is going to suggest that the user + // change the fn signature, but they may not be free to do so, + // since the signature must match the trait. + // + // FIXME(#42706) -- in some cases, we could do better here. + return true; + } + false + } + + /// Determines whether identifiers in the assembly have strict naming rules. + /// Currently, only NVPTX* targets need it. + pub fn has_strict_asm_symbol_naming(&self) -> bool { + self.sess.target.target.arch.contains("nvptx") + } + + /// Returns `&'static core::panic::Location<'static>`. + pub fn caller_location_ty(&self) -> Ty<'tcx> { + self.mk_imm_ref( + self.lifetimes.re_static, + self.type_of(self.require_lang_item(LangItem::PanicLocation, None)) + .subst(*self, self.mk_substs([self.lifetimes.re_static.into()].iter())), + ) + } + + /// Returns a displayable description and article for the given `def_id` (e.g. `("a", "struct")`). + pub fn article_and_description(&self, def_id: DefId) -> (&'static str, &'static str) { + match self.def_kind(def_id) { + DefKind::Generator => match self.generator_kind(def_id).unwrap() { + rustc_hir::GeneratorKind::Async(..) => ("an", "async closure"), + rustc_hir::GeneratorKind::Gen => ("a", "generator"), + }, + def_kind => (def_kind.article(), def_kind.descr(def_id)), + } + } +} + +/// A trait implemented for all `X<'a>` types that can be safely and +/// efficiently converted to `X<'tcx>` as long as they are part of the +/// provided `TyCtxt<'tcx>`. +/// This can be done, for example, for `Ty<'tcx>` or `SubstsRef<'tcx>` +/// by looking them up in their respective interners. +/// +/// However, this is still not the best implementation as it does +/// need to compare the components, even for interned values. +/// It would be more efficient if `TypedArena` provided a way to +/// determine whether the address is in the allocated range. +/// +/// `None` is returned if the value or one of the components is not part +/// of the provided context. +/// For `Ty`, `None` can be returned if either the type interner doesn't +/// contain the `TyKind` key or if the address of the interned +/// pointer differs. The latter case is possible if a primitive type, +/// e.g., `()` or `u8`, was interned in a different context. +pub trait Lift<'tcx>: fmt::Debug { + type Lifted: fmt::Debug + 'tcx; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>; +} + +macro_rules! nop_lift { + ($set:ident; $ty:ty => $lifted:ty) => { + impl<'a, 'tcx> Lift<'tcx> for $ty { + type Lifted = $lifted; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + if tcx.interners.$set.contains_pointer_to(&Interned(*self)) { + Some(unsafe { mem::transmute(*self) }) + } else { + None + } + } + } + }; +} + +macro_rules! nop_list_lift { + ($set:ident; $ty:ty => $lifted:ty) => { + impl<'a, 'tcx> Lift<'tcx> for &'a List<$ty> { + type Lifted = &'tcx List<$lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + if self.is_empty() { + return Some(List::empty()); + } + if tcx.interners.$set.contains_pointer_to(&Interned(*self)) { + Some(unsafe { mem::transmute(*self) }) + } else { + None + } + } + } + }; +} + +nop_lift! {type_; Ty<'a> => Ty<'tcx>} +nop_lift! {region; Region<'a> => Region<'tcx>} +nop_lift! {const_; &'a Const<'a> => &'tcx Const<'tcx>} +nop_lift! {predicate; &'a PredicateInner<'a> => &'tcx PredicateInner<'tcx>} + +nop_list_lift! {type_list; Ty<'a> => Ty<'tcx>} +nop_list_lift! {existential_predicates; ExistentialPredicate<'a> => ExistentialPredicate<'tcx>} +nop_list_lift! {predicates; Predicate<'a> => Predicate<'tcx>} +nop_list_lift! {canonical_var_infos; CanonicalVarInfo => CanonicalVarInfo} +nop_list_lift! {projs; ProjectionKind => ProjectionKind} + +// This is the impl for `&'a InternalSubsts<'a>`. +nop_list_lift! {substs; GenericArg<'a> => GenericArg<'tcx>} + +pub mod tls { + use super::{ptr_eq, GlobalCtxt, TyCtxt}; + + use crate::dep_graph::{DepKind, TaskDeps}; + use crate::ty::query; + use rustc_data_structures::sync::{self, Lock}; + use rustc_data_structures::thin_vec::ThinVec; + use rustc_errors::Diagnostic; + use std::mem; + + #[cfg(not(parallel_compiler))] + use std::cell::Cell; + + #[cfg(parallel_compiler)] + use rustc_rayon_core as rayon_core; + + /// This is the implicit state of rustc. It contains the current + /// `TyCtxt` and query. It is updated when creating a local interner or + /// executing a new query. Whenever there's a `TyCtxt` value available + /// you should also have access to an `ImplicitCtxt` through the functions + /// in this module. + #[derive(Clone)] + pub struct ImplicitCtxt<'a, 'tcx> { + /// The current `TyCtxt`. + pub tcx: TyCtxt<'tcx>, + + /// The current query job, if any. This is updated by `JobOwner::start` in + /// `ty::query::plumbing` when executing a query. + pub query: Option<query::QueryJobId<DepKind>>, + + /// Where to store diagnostics for the current query job, if any. + /// This is updated by `JobOwner::start` in `ty::query::plumbing` when executing a query. + pub diagnostics: Option<&'a Lock<ThinVec<Diagnostic>>>, + + /// Used to prevent layout from recursing too deeply. + pub layout_depth: usize, + + /// The current dep graph task. This is used to add dependencies to queries + /// when executing them. + pub task_deps: Option<&'a Lock<TaskDeps>>, + } + + impl<'a, 'tcx> ImplicitCtxt<'a, 'tcx> { + pub fn new(gcx: &'tcx GlobalCtxt<'tcx>) -> Self { + let tcx = TyCtxt { gcx }; + ImplicitCtxt { tcx, query: None, diagnostics: None, layout_depth: 0, task_deps: None } + } + } + + /// Sets Rayon's thread-local variable, which is preserved for Rayon jobs + /// to `value` during the call to `f`. It is restored to its previous value after. + /// This is used to set the pointer to the new `ImplicitCtxt`. + #[cfg(parallel_compiler)] + #[inline] + fn set_tlv<F: FnOnce() -> R, R>(value: usize, f: F) -> R { + rayon_core::tlv::with(value, f) + } + + /// Gets Rayon's thread-local variable, which is preserved for Rayon jobs. + /// This is used to get the pointer to the current `ImplicitCtxt`. + #[cfg(parallel_compiler)] + #[inline] + pub fn get_tlv() -> usize { + rayon_core::tlv::get() + } + + #[cfg(not(parallel_compiler))] + thread_local! { + /// A thread local variable that stores a pointer to the current `ImplicitCtxt`. + static TLV: Cell<usize> = Cell::new(0); + } + + /// Sets TLV to `value` during the call to `f`. + /// It is restored to its previous value after. + /// This is used to set the pointer to the new `ImplicitCtxt`. + #[cfg(not(parallel_compiler))] + #[inline] + fn set_tlv<F: FnOnce() -> R, R>(value: usize, f: F) -> R { + let old = get_tlv(); + let _reset = rustc_data_structures::OnDrop(move || TLV.with(|tlv| tlv.set(old))); + TLV.with(|tlv| tlv.set(value)); + f() + } + + /// Gets the pointer to the current `ImplicitCtxt`. + #[cfg(not(parallel_compiler))] + #[inline] + fn get_tlv() -> usize { + TLV.with(|tlv| tlv.get()) + } + + /// Sets `context` as the new current `ImplicitCtxt` for the duration of the function `f`. + #[inline] + pub fn enter_context<'a, 'tcx, F, R>(context: &ImplicitCtxt<'a, 'tcx>, f: F) -> R + where + F: FnOnce(&ImplicitCtxt<'a, 'tcx>) -> R, + { + set_tlv(context as *const _ as usize, || f(&context)) + } + + /// Allows access to the current `ImplicitCtxt` in a closure if one is available. + #[inline] + pub fn with_context_opt<F, R>(f: F) -> R + where + F: for<'a, 'tcx> FnOnce(Option<&ImplicitCtxt<'a, 'tcx>>) -> R, + { + let context = get_tlv(); + if context == 0 { + f(None) + } else { + // We could get a `ImplicitCtxt` pointer from another thread. + // Ensure that `ImplicitCtxt` is `Sync`. + sync::assert_sync::<ImplicitCtxt<'_, '_>>(); + + unsafe { f(Some(&*(context as *const ImplicitCtxt<'_, '_>))) } + } + } + + /// Allows access to the current `ImplicitCtxt`. + /// Panics if there is no `ImplicitCtxt` available. + #[inline] + pub fn with_context<F, R>(f: F) -> R + where + F: for<'a, 'tcx> FnOnce(&ImplicitCtxt<'a, 'tcx>) -> R, + { + with_context_opt(|opt_context| f(opt_context.expect("no ImplicitCtxt stored in tls"))) + } + + /// Allows access to the current `ImplicitCtxt` whose tcx field is the same as the tcx argument + /// passed in. This means the closure is given an `ImplicitCtxt` with the same `'tcx` lifetime + /// as the `TyCtxt` passed in. + /// This will panic if you pass it a `TyCtxt` which is different from the current + /// `ImplicitCtxt`'s `tcx` field. + #[inline] + pub fn with_related_context<'tcx, F, R>(tcx: TyCtxt<'tcx>, f: F) -> R + where + F: FnOnce(&ImplicitCtxt<'_, 'tcx>) -> R, + { + with_context(|context| unsafe { + assert!(ptr_eq(context.tcx.gcx, tcx.gcx)); + let context: &ImplicitCtxt<'_, '_> = mem::transmute(context); + f(context) + }) + } + + /// Allows access to the `TyCtxt` in the current `ImplicitCtxt`. + /// Panics if there is no `ImplicitCtxt` available. + #[inline] + pub fn with<F, R>(f: F) -> R + where + F: for<'tcx> FnOnce(TyCtxt<'tcx>) -> R, + { + with_context(|context| f(context.tcx)) + } + + /// Allows access to the `TyCtxt` in the current `ImplicitCtxt`. + /// The closure is passed None if there is no `ImplicitCtxt` available. + #[inline] + pub fn with_opt<F, R>(f: F) -> R + where + F: for<'tcx> FnOnce(Option<TyCtxt<'tcx>>) -> R, + { + with_context_opt(|opt_context| f(opt_context.map(|context| context.tcx))) + } +} + +macro_rules! sty_debug_print { + ($fmt: expr, $ctxt: expr, $($variant: ident),*) => {{ + // Curious inner module to allow variant names to be used as + // variable names. + #[allow(non_snake_case)] + mod inner { + use crate::ty::{self, TyCtxt}; + use crate::ty::context::Interned; + + #[derive(Copy, Clone)] + struct DebugStat { + total: usize, + lt_infer: usize, + ty_infer: usize, + ct_infer: usize, + all_infer: usize, + } + + pub fn go(fmt: &mut std::fmt::Formatter<'_>, tcx: TyCtxt<'_>) -> std::fmt::Result { + let mut total = DebugStat { + total: 0, + lt_infer: 0, + ty_infer: 0, + ct_infer: 0, + all_infer: 0, + }; + $(let mut $variant = total;)* + + let shards = tcx.interners.type_.lock_shards(); + let types = shards.iter().flat_map(|shard| shard.keys()); + for &Interned(t) in types { + let variant = match t.kind { + ty::Bool | ty::Char | ty::Int(..) | ty::Uint(..) | + ty::Float(..) | ty::Str | ty::Never => continue, + ty::Error(_) => /* unimportant */ continue, + $(ty::$variant(..) => &mut $variant,)* + }; + let lt = t.flags.intersects(ty::TypeFlags::HAS_RE_INFER); + let ty = t.flags.intersects(ty::TypeFlags::HAS_TY_INFER); + let ct = t.flags.intersects(ty::TypeFlags::HAS_CT_INFER); + + variant.total += 1; + total.total += 1; + if lt { total.lt_infer += 1; variant.lt_infer += 1 } + if ty { total.ty_infer += 1; variant.ty_infer += 1 } + if ct { total.ct_infer += 1; variant.ct_infer += 1 } + if lt && ty && ct { total.all_infer += 1; variant.all_infer += 1 } + } + writeln!(fmt, "Ty interner total ty lt ct all")?; + $(writeln!(fmt, " {:18}: {uses:6} {usespc:4.1}%, \ + {ty:4.1}% {lt:5.1}% {ct:4.1}% {all:4.1}%", + stringify!($variant), + uses = $variant.total, + usespc = $variant.total as f64 * 100.0 / total.total as f64, + ty = $variant.ty_infer as f64 * 100.0 / total.total as f64, + lt = $variant.lt_infer as f64 * 100.0 / total.total as f64, + ct = $variant.ct_infer as f64 * 100.0 / total.total as f64, + all = $variant.all_infer as f64 * 100.0 / total.total as f64)?; + )* + writeln!(fmt, " total {uses:6} \ + {ty:4.1}% {lt:5.1}% {ct:4.1}% {all:4.1}%", + uses = total.total, + ty = total.ty_infer as f64 * 100.0 / total.total as f64, + lt = total.lt_infer as f64 * 100.0 / total.total as f64, + ct = total.ct_infer as f64 * 100.0 / total.total as f64, + all = total.all_infer as f64 * 100.0 / total.total as f64) + } + } + + inner::go($fmt, $ctxt) + }} +} + +impl<'tcx> TyCtxt<'tcx> { + pub fn debug_stats(self) -> impl std::fmt::Debug + 'tcx { + struct DebugStats<'tcx>(TyCtxt<'tcx>); + + impl std::fmt::Debug for DebugStats<'tcx> { + fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + sty_debug_print!( + fmt, + self.0, + Adt, + Array, + Slice, + RawPtr, + Ref, + FnDef, + FnPtr, + Placeholder, + Generator, + GeneratorWitness, + Dynamic, + Closure, + Tuple, + Bound, + Param, + Infer, + Projection, + Opaque, + Foreign + )?; + + writeln!(fmt, "InternalSubsts interner: #{}", self.0.interners.substs.len())?; + writeln!(fmt, "Region interner: #{}", self.0.interners.region.len())?; + writeln!(fmt, "Stability interner: #{}", self.0.stability_interner.len())?; + writeln!( + fmt, + "Const Stability interner: #{}", + self.0.const_stability_interner.len() + )?; + writeln!(fmt, "Allocation interner: #{}", self.0.allocation_interner.len())?; + writeln!(fmt, "Layout interner: #{}", self.0.layout_interner.len())?; + + Ok(()) + } + } + + DebugStats(self) + } +} + +/// An entry in an interner. +struct Interned<'tcx, T: ?Sized>(&'tcx T); + +impl<'tcx, T: 'tcx + ?Sized> Clone for Interned<'tcx, T> { + fn clone(&self) -> Self { + Interned(self.0) + } +} +impl<'tcx, T: 'tcx + ?Sized> Copy for Interned<'tcx, T> {} + +impl<'tcx, T: 'tcx + ?Sized> IntoPointer for Interned<'tcx, T> { + fn into_pointer(&self) -> *const () { + self.0 as *const _ as *const () + } +} +// N.B., an `Interned<Ty>` compares and hashes as a `TyKind`. +impl<'tcx> PartialEq for Interned<'tcx, TyS<'tcx>> { + fn eq(&self, other: &Interned<'tcx, TyS<'tcx>>) -> bool { + self.0.kind == other.0.kind + } +} + +impl<'tcx> Eq for Interned<'tcx, TyS<'tcx>> {} + +impl<'tcx> Hash for Interned<'tcx, TyS<'tcx>> { + fn hash<H: Hasher>(&self, s: &mut H) { + self.0.kind.hash(s) + } +} + +#[allow(rustc::usage_of_ty_tykind)] +impl<'tcx> Borrow<TyKind<'tcx>> for Interned<'tcx, TyS<'tcx>> { + fn borrow<'a>(&'a self) -> &'a TyKind<'tcx> { + &self.0.kind + } +} +// N.B., an `Interned<PredicateInner>` compares and hashes as a `PredicateKind`. +impl<'tcx> PartialEq for Interned<'tcx, PredicateInner<'tcx>> { + fn eq(&self, other: &Interned<'tcx, PredicateInner<'tcx>>) -> bool { + self.0.kind == other.0.kind + } +} + +impl<'tcx> Eq for Interned<'tcx, PredicateInner<'tcx>> {} + +impl<'tcx> Hash for Interned<'tcx, PredicateInner<'tcx>> { + fn hash<H: Hasher>(&self, s: &mut H) { + self.0.kind.hash(s) + } +} + +impl<'tcx> Borrow<PredicateKind<'tcx>> for Interned<'tcx, PredicateInner<'tcx>> { + fn borrow<'a>(&'a self) -> &'a PredicateKind<'tcx> { + &self.0.kind + } +} + +// N.B., an `Interned<List<T>>` compares and hashes as its elements. +impl<'tcx, T: PartialEq> PartialEq for Interned<'tcx, List<T>> { + fn eq(&self, other: &Interned<'tcx, List<T>>) -> bool { + self.0[..] == other.0[..] + } +} + +impl<'tcx, T: Eq> Eq for Interned<'tcx, List<T>> {} + +impl<'tcx, T: Hash> Hash for Interned<'tcx, List<T>> { + fn hash<H: Hasher>(&self, s: &mut H) { + self.0[..].hash(s) + } +} + +impl<'tcx, T> Borrow<[T]> for Interned<'tcx, List<T>> { + fn borrow<'a>(&'a self) -> &'a [T] { + &self.0[..] + } +} + +impl<'tcx> Borrow<RegionKind> for Interned<'tcx, RegionKind> { + fn borrow(&self) -> &RegionKind { + &self.0 + } +} + +impl<'tcx> Borrow<Const<'tcx>> for Interned<'tcx, Const<'tcx>> { + fn borrow<'a>(&'a self) -> &'a Const<'tcx> { + &self.0 + } +} + +impl<'tcx> Borrow<PredicateKind<'tcx>> for Interned<'tcx, PredicateKind<'tcx>> { + fn borrow<'a>(&'a self) -> &'a PredicateKind<'tcx> { + &self.0 + } +} + +macro_rules! direct_interners { + ($($name:ident: $method:ident($ty:ty),)+) => { + $(impl<'tcx> PartialEq for Interned<'tcx, $ty> { + fn eq(&self, other: &Self) -> bool { + self.0 == other.0 + } + } + + impl<'tcx> Eq for Interned<'tcx, $ty> {} + + impl<'tcx> Hash for Interned<'tcx, $ty> { + fn hash<H: Hasher>(&self, s: &mut H) { + self.0.hash(s) + } + } + + impl<'tcx> TyCtxt<'tcx> { + pub fn $method(self, v: $ty) -> &'tcx $ty { + self.interners.$name.intern_ref(&v, || { + Interned(self.interners.arena.alloc(v)) + }).0 + } + })+ + } +} + +direct_interners! { + region: mk_region(RegionKind), + const_: mk_const(Const<'tcx>), +} + +macro_rules! slice_interners { + ($($field:ident: $method:ident($ty:ty)),+) => ( + $(impl<'tcx> TyCtxt<'tcx> { + pub fn $method(self, v: &[$ty]) -> &'tcx List<$ty> { + self.interners.$field.intern_ref(v, || { + Interned(List::from_arena(&*self.arena, v)) + }).0 + } + })+ + ); +} + +slice_interners!( + type_list: _intern_type_list(Ty<'tcx>), + substs: _intern_substs(GenericArg<'tcx>), + canonical_var_infos: _intern_canonical_var_infos(CanonicalVarInfo), + existential_predicates: _intern_existential_predicates(ExistentialPredicate<'tcx>), + predicates: _intern_predicates(Predicate<'tcx>), + projs: _intern_projs(ProjectionKind), + place_elems: _intern_place_elems(PlaceElem<'tcx>), + chalk_environment_clause_list: + _intern_chalk_environment_clause_list(traits::ChalkEnvironmentClause<'tcx>) +); + +impl<'tcx> TyCtxt<'tcx> { + /// Given a `fn` type, returns an equivalent `unsafe fn` type; + /// that is, a `fn` type that is equivalent in every way for being + /// unsafe. + pub fn safe_to_unsafe_fn_ty(self, sig: PolyFnSig<'tcx>) -> Ty<'tcx> { + assert_eq!(sig.unsafety(), hir::Unsafety::Normal); + self.mk_fn_ptr(sig.map_bound(|sig| ty::FnSig { unsafety: hir::Unsafety::Unsafe, ..sig })) + } + + /// Given a closure signature, returns an equivalent fn signature. Detuples + /// and so forth -- so e.g., if we have a sig with `Fn<(u32, i32)>` then + /// you would get a `fn(u32, i32)`. + /// `unsafety` determines the unsafety of the fn signature. If you pass + /// `hir::Unsafety::Unsafe` in the previous example, then you would get + /// an `unsafe fn (u32, i32)`. + /// It cannot convert a closure that requires unsafe. + pub fn signature_unclosure( + self, + sig: PolyFnSig<'tcx>, + unsafety: hir::Unsafety, + ) -> PolyFnSig<'tcx> { + sig.map_bound(|s| { + let params_iter = match s.inputs()[0].kind { + ty::Tuple(params) => params.into_iter().map(|k| k.expect_ty()), + _ => bug!(), + }; + self.mk_fn_sig(params_iter, s.output(), s.c_variadic, unsafety, abi::Abi::Rust) + }) + } + + /// Same a `self.mk_region(kind)`, but avoids accessing the interners if + /// `*r == kind`. + #[inline] + pub fn reuse_or_mk_region(self, r: Region<'tcx>, kind: RegionKind) -> Region<'tcx> { + if *r == kind { r } else { self.mk_region(kind) } + } + + #[allow(rustc::usage_of_ty_tykind)] + #[inline] + pub fn mk_ty(self, st: TyKind<'tcx>) -> Ty<'tcx> { + self.interners.intern_ty(st) + } + + #[inline] + pub fn mk_predicate(self, kind: PredicateKind<'tcx>) -> Predicate<'tcx> { + let inner = self.interners.intern_predicate(kind); + Predicate { inner } + } + + #[inline] + pub fn reuse_or_mk_predicate( + self, + pred: Predicate<'tcx>, + kind: PredicateKind<'tcx>, + ) -> Predicate<'tcx> { + if *pred.kind() != kind { self.mk_predicate(kind) } else { pred } + } + + pub fn mk_mach_int(self, tm: ast::IntTy) -> Ty<'tcx> { + match tm { + ast::IntTy::Isize => self.types.isize, + ast::IntTy::I8 => self.types.i8, + ast::IntTy::I16 => self.types.i16, + ast::IntTy::I32 => self.types.i32, + ast::IntTy::I64 => self.types.i64, + ast::IntTy::I128 => self.types.i128, + } + } + + pub fn mk_mach_uint(self, tm: ast::UintTy) -> Ty<'tcx> { + match tm { + ast::UintTy::Usize => self.types.usize, + ast::UintTy::U8 => self.types.u8, + ast::UintTy::U16 => self.types.u16, + ast::UintTy::U32 => self.types.u32, + ast::UintTy::U64 => self.types.u64, + ast::UintTy::U128 => self.types.u128, + } + } + + pub fn mk_mach_float(self, tm: ast::FloatTy) -> Ty<'tcx> { + match tm { + ast::FloatTy::F32 => self.types.f32, + ast::FloatTy::F64 => self.types.f64, + } + } + + #[inline] + pub fn mk_static_str(self) -> Ty<'tcx> { + self.mk_imm_ref(self.lifetimes.re_static, self.types.str_) + } + + #[inline] + pub fn mk_adt(self, def: &'tcx AdtDef, substs: SubstsRef<'tcx>) -> Ty<'tcx> { + // Take a copy of substs so that we own the vectors inside. + self.mk_ty(Adt(def, substs)) + } + + #[inline] + pub fn mk_foreign(self, def_id: DefId) -> Ty<'tcx> { + self.mk_ty(Foreign(def_id)) + } + + fn mk_generic_adt(self, wrapper_def_id: DefId, ty_param: Ty<'tcx>) -> Ty<'tcx> { + let adt_def = self.adt_def(wrapper_def_id); + let substs = + InternalSubsts::for_item(self, wrapper_def_id, |param, substs| match param.kind { + GenericParamDefKind::Lifetime | GenericParamDefKind::Const => bug!(), + GenericParamDefKind::Type { has_default, .. } => { + if param.index == 0 { + ty_param.into() + } else { + assert!(has_default); + self.type_of(param.def_id).subst(self, substs).into() + } + } + }); + self.mk_ty(Adt(adt_def, substs)) + } + + #[inline] + pub fn mk_box(self, ty: Ty<'tcx>) -> Ty<'tcx> { + let def_id = self.require_lang_item(LangItem::OwnedBox, None); + self.mk_generic_adt(def_id, ty) + } + + #[inline] + pub fn mk_lang_item(self, ty: Ty<'tcx>, item: LangItem) -> Option<Ty<'tcx>> { + let def_id = self.lang_items().require(item).ok()?; + Some(self.mk_generic_adt(def_id, ty)) + } + + #[inline] + pub fn mk_diagnostic_item(self, ty: Ty<'tcx>, name: Symbol) -> Option<Ty<'tcx>> { + let def_id = self.get_diagnostic_item(name)?; + Some(self.mk_generic_adt(def_id, ty)) + } + + #[inline] + pub fn mk_maybe_uninit(self, ty: Ty<'tcx>) -> Ty<'tcx> { + let def_id = self.require_lang_item(LangItem::MaybeUninit, None); + self.mk_generic_adt(def_id, ty) + } + + #[inline] + pub fn mk_ptr(self, tm: TypeAndMut<'tcx>) -> Ty<'tcx> { + self.mk_ty(RawPtr(tm)) + } + + #[inline] + pub fn mk_ref(self, r: Region<'tcx>, tm: TypeAndMut<'tcx>) -> Ty<'tcx> { + self.mk_ty(Ref(r, tm.ty, tm.mutbl)) + } + + #[inline] + pub fn mk_mut_ref(self, r: Region<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> { + self.mk_ref(r, TypeAndMut { ty, mutbl: hir::Mutability::Mut }) + } + + #[inline] + pub fn mk_imm_ref(self, r: Region<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> { + self.mk_ref(r, TypeAndMut { ty, mutbl: hir::Mutability::Not }) + } + + #[inline] + pub fn mk_mut_ptr(self, ty: Ty<'tcx>) -> Ty<'tcx> { + self.mk_ptr(TypeAndMut { ty, mutbl: hir::Mutability::Mut }) + } + + #[inline] + pub fn mk_imm_ptr(self, ty: Ty<'tcx>) -> Ty<'tcx> { + self.mk_ptr(TypeAndMut { ty, mutbl: hir::Mutability::Not }) + } + + #[inline] + pub fn mk_nil_ptr(self) -> Ty<'tcx> { + self.mk_imm_ptr(self.mk_unit()) + } + + #[inline] + pub fn mk_array(self, ty: Ty<'tcx>, n: u64) -> Ty<'tcx> { + self.mk_ty(Array(ty, ty::Const::from_usize(self, n))) + } + + #[inline] + pub fn mk_slice(self, ty: Ty<'tcx>) -> Ty<'tcx> { + self.mk_ty(Slice(ty)) + } + + #[inline] + pub fn intern_tup(self, ts: &[Ty<'tcx>]) -> Ty<'tcx> { + let kinds: Vec<_> = ts.iter().map(|&t| GenericArg::from(t)).collect(); + self.mk_ty(Tuple(self.intern_substs(&kinds))) + } + + pub fn mk_tup<I: InternAs<[Ty<'tcx>], Ty<'tcx>>>(self, iter: I) -> I::Output { + iter.intern_with(|ts| { + let kinds: Vec<_> = ts.iter().map(|&t| GenericArg::from(t)).collect(); + self.mk_ty(Tuple(self.intern_substs(&kinds))) + }) + } + + #[inline] + pub fn mk_unit(self) -> Ty<'tcx> { + self.types.unit + } + + #[inline] + pub fn mk_diverging_default(self) -> Ty<'tcx> { + if self.features().never_type_fallback { self.types.never } else { self.types.unit } + } + + #[inline] + pub fn mk_fn_def(self, def_id: DefId, substs: SubstsRef<'tcx>) -> Ty<'tcx> { + self.mk_ty(FnDef(def_id, substs)) + } + + #[inline] + pub fn mk_fn_ptr(self, fty: PolyFnSig<'tcx>) -> Ty<'tcx> { + self.mk_ty(FnPtr(fty)) + } + + #[inline] + pub fn mk_dynamic( + self, + obj: ty::Binder<&'tcx List<ExistentialPredicate<'tcx>>>, + reg: ty::Region<'tcx>, + ) -> Ty<'tcx> { + self.mk_ty(Dynamic(obj, reg)) + } + + #[inline] + pub fn mk_projection(self, item_def_id: DefId, substs: SubstsRef<'tcx>) -> Ty<'tcx> { + self.mk_ty(Projection(ProjectionTy { item_def_id, substs })) + } + + #[inline] + pub fn mk_closure(self, closure_id: DefId, closure_substs: SubstsRef<'tcx>) -> Ty<'tcx> { + self.mk_ty(Closure(closure_id, closure_substs)) + } + + #[inline] + pub fn mk_generator( + self, + id: DefId, + generator_substs: SubstsRef<'tcx>, + movability: hir::Movability, + ) -> Ty<'tcx> { + self.mk_ty(Generator(id, generator_substs, movability)) + } + + #[inline] + pub fn mk_generator_witness(self, types: ty::Binder<&'tcx List<Ty<'tcx>>>) -> Ty<'tcx> { + self.mk_ty(GeneratorWitness(types)) + } + + #[inline] + pub fn mk_ty_var(self, v: TyVid) -> Ty<'tcx> { + self.mk_ty_infer(TyVar(v)) + } + + #[inline] + pub fn mk_const_var(self, v: ConstVid<'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> { + self.mk_const(ty::Const { val: ty::ConstKind::Infer(InferConst::Var(v)), ty }) + } + + #[inline] + pub fn mk_int_var(self, v: IntVid) -> Ty<'tcx> { + self.mk_ty_infer(IntVar(v)) + } + + #[inline] + pub fn mk_float_var(self, v: FloatVid) -> Ty<'tcx> { + self.mk_ty_infer(FloatVar(v)) + } + + #[inline] + pub fn mk_ty_infer(self, it: InferTy) -> Ty<'tcx> { + self.mk_ty(Infer(it)) + } + + #[inline] + pub fn mk_const_infer(self, ic: InferConst<'tcx>, ty: Ty<'tcx>) -> &'tcx ty::Const<'tcx> { + self.mk_const(ty::Const { val: ty::ConstKind::Infer(ic), ty }) + } + + #[inline] + pub fn mk_ty_param(self, index: u32, name: Symbol) -> Ty<'tcx> { + self.mk_ty(Param(ParamTy { index, name })) + } + + #[inline] + pub fn mk_const_param(self, index: u32, name: Symbol, ty: Ty<'tcx>) -> &'tcx Const<'tcx> { + self.mk_const(ty::Const { val: ty::ConstKind::Param(ParamConst { index, name }), ty }) + } + + pub fn mk_param_from_def(self, param: &ty::GenericParamDef) -> GenericArg<'tcx> { + match param.kind { + GenericParamDefKind::Lifetime => { + self.mk_region(ty::ReEarlyBound(param.to_early_bound_region_data())).into() + } + GenericParamDefKind::Type { .. } => self.mk_ty_param(param.index, param.name).into(), + GenericParamDefKind::Const => { + self.mk_const_param(param.index, param.name, self.type_of(param.def_id)).into() + } + } + } + + #[inline] + pub fn mk_opaque(self, def_id: DefId, substs: SubstsRef<'tcx>) -> Ty<'tcx> { + self.mk_ty(Opaque(def_id, substs)) + } + + pub fn mk_place_field(self, place: Place<'tcx>, f: Field, ty: Ty<'tcx>) -> Place<'tcx> { + self.mk_place_elem(place, PlaceElem::Field(f, ty)) + } + + pub fn mk_place_deref(self, place: Place<'tcx>) -> Place<'tcx> { + self.mk_place_elem(place, PlaceElem::Deref) + } + + pub fn mk_place_downcast( + self, + place: Place<'tcx>, + adt_def: &'tcx AdtDef, + variant_index: VariantIdx, + ) -> Place<'tcx> { + self.mk_place_elem( + place, + PlaceElem::Downcast(Some(adt_def.variants[variant_index].ident.name), variant_index), + ) + } + + pub fn mk_place_downcast_unnamed( + self, + place: Place<'tcx>, + variant_index: VariantIdx, + ) -> Place<'tcx> { + self.mk_place_elem(place, PlaceElem::Downcast(None, variant_index)) + } + + pub fn mk_place_index(self, place: Place<'tcx>, index: Local) -> Place<'tcx> { + self.mk_place_elem(place, PlaceElem::Index(index)) + } + + /// This method copies `Place`'s projection, add an element and reintern it. Should not be used + /// to build a full `Place` it's just a convenient way to grab a projection and modify it in + /// flight. + pub fn mk_place_elem(self, place: Place<'tcx>, elem: PlaceElem<'tcx>) -> Place<'tcx> { + let mut projection = place.projection.to_vec(); + projection.push(elem); + + Place { local: place.local, projection: self.intern_place_elems(&projection) } + } + + pub fn intern_existential_predicates( + self, + eps: &[ExistentialPredicate<'tcx>], + ) -> &'tcx List<ExistentialPredicate<'tcx>> { + assert!(!eps.is_empty()); + assert!(eps.windows(2).all(|w| w[0].stable_cmp(self, &w[1]) != Ordering::Greater)); + self._intern_existential_predicates(eps) + } + + pub fn intern_predicates(self, preds: &[Predicate<'tcx>]) -> &'tcx List<Predicate<'tcx>> { + // FIXME consider asking the input slice to be sorted to avoid + // re-interning permutations, in which case that would be asserted + // here. + if preds.is_empty() { + // The macro-generated method below asserts we don't intern an empty slice. + List::empty() + } else { + self._intern_predicates(preds) + } + } + + pub fn intern_type_list(self, ts: &[Ty<'tcx>]) -> &'tcx List<Ty<'tcx>> { + if ts.is_empty() { List::empty() } else { self._intern_type_list(ts) } + } + + pub fn intern_substs(self, ts: &[GenericArg<'tcx>]) -> &'tcx List<GenericArg<'tcx>> { + if ts.is_empty() { List::empty() } else { self._intern_substs(ts) } + } + + pub fn intern_projs(self, ps: &[ProjectionKind]) -> &'tcx List<ProjectionKind> { + if ps.is_empty() { List::empty() } else { self._intern_projs(ps) } + } + + pub fn intern_place_elems(self, ts: &[PlaceElem<'tcx>]) -> &'tcx List<PlaceElem<'tcx>> { + if ts.is_empty() { List::empty() } else { self._intern_place_elems(ts) } + } + + pub fn intern_canonical_var_infos(self, ts: &[CanonicalVarInfo]) -> CanonicalVarInfos<'tcx> { + if ts.is_empty() { List::empty() } else { self._intern_canonical_var_infos(ts) } + } + + pub fn intern_chalk_environment_clause_list( + self, + ts: &[traits::ChalkEnvironmentClause<'tcx>], + ) -> &'tcx List<traits::ChalkEnvironmentClause<'tcx>> { + if ts.is_empty() { List::empty() } else { self._intern_chalk_environment_clause_list(ts) } + } + + pub fn mk_fn_sig<I>( + self, + inputs: I, + output: I::Item, + c_variadic: bool, + unsafety: hir::Unsafety, + abi: abi::Abi, + ) -> <I::Item as InternIteratorElement<Ty<'tcx>, ty::FnSig<'tcx>>>::Output + where + I: Iterator<Item: InternIteratorElement<Ty<'tcx>, ty::FnSig<'tcx>>>, + { + inputs.chain(iter::once(output)).intern_with(|xs| ty::FnSig { + inputs_and_output: self.intern_type_list(xs), + c_variadic, + unsafety, + abi, + }) + } + + pub fn mk_existential_predicates< + I: InternAs<[ExistentialPredicate<'tcx>], &'tcx List<ExistentialPredicate<'tcx>>>, + >( + self, + iter: I, + ) -> I::Output { + iter.intern_with(|xs| self.intern_existential_predicates(xs)) + } + + pub fn mk_predicates<I: InternAs<[Predicate<'tcx>], &'tcx List<Predicate<'tcx>>>>( + self, + iter: I, + ) -> I::Output { + iter.intern_with(|xs| self.intern_predicates(xs)) + } + + pub fn mk_type_list<I: InternAs<[Ty<'tcx>], &'tcx List<Ty<'tcx>>>>(self, iter: I) -> I::Output { + iter.intern_with(|xs| self.intern_type_list(xs)) + } + + pub fn mk_substs<I: InternAs<[GenericArg<'tcx>], &'tcx List<GenericArg<'tcx>>>>( + self, + iter: I, + ) -> I::Output { + iter.intern_with(|xs| self.intern_substs(xs)) + } + + pub fn mk_place_elems<I: InternAs<[PlaceElem<'tcx>], &'tcx List<PlaceElem<'tcx>>>>( + self, + iter: I, + ) -> I::Output { + iter.intern_with(|xs| self.intern_place_elems(xs)) + } + + pub fn mk_substs_trait(self, self_ty: Ty<'tcx>, rest: &[GenericArg<'tcx>]) -> SubstsRef<'tcx> { + self.mk_substs(iter::once(self_ty.into()).chain(rest.iter().cloned())) + } + + pub fn mk_chalk_environment_clause_list< + I: InternAs< + [traits::ChalkEnvironmentClause<'tcx>], + &'tcx List<traits::ChalkEnvironmentClause<'tcx>>, + >, + >( + self, + iter: I, + ) -> I::Output { + iter.intern_with(|xs| self.intern_chalk_environment_clause_list(xs)) + } + + /// Walks upwards from `id` to find a node which might change lint levels with attributes. + /// It stops at `bound` and just returns it if reached. + pub fn maybe_lint_level_root_bounded(self, mut id: HirId, bound: HirId) -> HirId { + let hir = self.hir(); + loop { + if id == bound { + return bound; + } + + if hir.attrs(id).iter().any(|attr| Level::from_symbol(attr.name_or_empty()).is_some()) { + return id; + } + let next = hir.get_parent_node(id); + if next == id { + bug!("lint traversal reached the root of the crate"); + } + id = next; + } + } + + pub fn lint_level_at_node( + self, + lint: &'static Lint, + mut id: hir::HirId, + ) -> (Level, LintSource) { + let sets = self.lint_levels(LOCAL_CRATE); + loop { + if let Some(pair) = sets.level_and_source(lint, id, self.sess) { + return pair; + } + let next = self.hir().get_parent_node(id); + if next == id { + bug!("lint traversal reached the root of the crate"); + } + id = next; + } + } + + pub fn struct_span_lint_hir( + self, + lint: &'static Lint, + hir_id: HirId, + span: impl Into<MultiSpan>, + decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>), + ) { + let (level, src) = self.lint_level_at_node(lint, hir_id); + struct_lint_level(self.sess, lint, level, src, Some(span.into()), decorate); + } + + pub fn struct_lint_node( + self, + lint: &'static Lint, + id: HirId, + decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>), + ) { + let (level, src) = self.lint_level_at_node(lint, id); + struct_lint_level(self.sess, lint, level, src, None, decorate); + } + + pub fn in_scope_traits(self, id: HirId) -> Option<&'tcx StableVec<TraitCandidate>> { + self.in_scope_traits_map(id.owner).and_then(|map| map.get(&id.local_id)) + } + + pub fn named_region(self, id: HirId) -> Option<resolve_lifetime::Region> { + self.named_region_map(id.owner).and_then(|map| map.get(&id.local_id).cloned()) + } + + pub fn is_late_bound(self, id: HirId) -> bool { + self.is_late_bound_map(id.owner).map(|set| set.contains(&id.local_id)).unwrap_or(false) + } + + pub fn object_lifetime_defaults(self, id: HirId) -> Option<&'tcx [ObjectLifetimeDefault]> { + self.object_lifetime_defaults_map(id.owner) + .and_then(|map| map.get(&id.local_id).map(|v| &**v)) + } +} + +impl TyCtxtAt<'tcx> { + /// Constructs a `TyKind::Error` type and registers a `delay_span_bug` to ensure it gets used. + #[track_caller] + pub fn ty_error(self) -> Ty<'tcx> { + self.tcx.ty_error_with_message(self.span, "TyKind::Error constructed but no error reported") + } + + /// Constructs a `TyKind::Error` type and registers a `delay_span_bug` with the given `msg to + /// ensure it gets used. + #[track_caller] + pub fn ty_error_with_message(self, msg: &str) -> Ty<'tcx> { + self.tcx.ty_error_with_message(self.span, msg) + } +} + +pub trait InternAs<T: ?Sized, R> { + type Output; + fn intern_with<F>(self, f: F) -> Self::Output + where + F: FnOnce(&T) -> R; +} + +impl<I, T, R, E> InternAs<[T], R> for I +where + E: InternIteratorElement<T, R>, + I: Iterator<Item = E>, +{ + type Output = E::Output; + fn intern_with<F>(self, f: F) -> Self::Output + where + F: FnOnce(&[T]) -> R, + { + E::intern_with(self, f) + } +} + +pub trait InternIteratorElement<T, R>: Sized { + type Output; + fn intern_with<I: Iterator<Item = Self>, F: FnOnce(&[T]) -> R>(iter: I, f: F) -> Self::Output; +} + +impl<T, R> InternIteratorElement<T, R> for T { + type Output = R; + fn intern_with<I: Iterator<Item = Self>, F: FnOnce(&[T]) -> R>(iter: I, f: F) -> Self::Output { + f(&iter.collect::<SmallVec<[_; 8]>>()) + } +} + +impl<'a, T, R> InternIteratorElement<T, R> for &'a T +where + T: Clone + 'a, +{ + type Output = R; + fn intern_with<I: Iterator<Item = Self>, F: FnOnce(&[T]) -> R>(iter: I, f: F) -> Self::Output { + f(&iter.cloned().collect::<SmallVec<[_; 8]>>()) + } +} + +impl<T, R, E> InternIteratorElement<T, R> for Result<T, E> { + type Output = Result<R, E>; + fn intern_with<I: Iterator<Item = Self>, F: FnOnce(&[T]) -> R>( + mut iter: I, + f: F, + ) -> Self::Output { + // This code is hot enough that it's worth specializing for the most + // common length lists, to avoid the overhead of `SmallVec` creation. + // The match arms are in order of frequency. The 1, 2, and 0 cases are + // typically hit in ~95% of cases. We assume that if the upper and + // lower bounds from `size_hint` agree they are correct. + Ok(match iter.size_hint() { + (1, Some(1)) => { + let t0 = iter.next().unwrap()?; + assert!(iter.next().is_none()); + f(&[t0]) + } + (2, Some(2)) => { + let t0 = iter.next().unwrap()?; + let t1 = iter.next().unwrap()?; + assert!(iter.next().is_none()); + f(&[t0, t1]) + } + (0, Some(0)) => { + assert!(iter.next().is_none()); + f(&[]) + } + _ => f(&iter.collect::<Result<SmallVec<[_; 8]>, _>>()?), + }) + } +} + +// We are comparing types with different invariant lifetimes, so `ptr::eq` +// won't work for us. +fn ptr_eq<T, U>(t: *const T, u: *const U) -> bool { + t as *const () == u as *const () +} + +pub fn provide(providers: &mut ty::query::Providers) { + providers.in_scope_traits_map = |tcx, id| tcx.gcx.trait_map.get(&id); + providers.module_exports = |tcx, id| tcx.gcx.export_map.get(&id).map(|v| &v[..]); + providers.crate_name = |tcx, id| { + assert_eq!(id, LOCAL_CRATE); + tcx.crate_name + }; + providers.maybe_unused_trait_import = |tcx, id| tcx.maybe_unused_trait_imports.contains(&id); + providers.maybe_unused_extern_crates = |tcx, cnum| { + assert_eq!(cnum, LOCAL_CRATE); + &tcx.maybe_unused_extern_crates[..] + }; + providers.names_imported_by_glob_use = + |tcx, id| tcx.arena.alloc(tcx.glob_map.get(&id).cloned().unwrap_or_default()); + + providers.lookup_stability = |tcx, id| { + let id = tcx.hir().local_def_id_to_hir_id(id.expect_local()); + tcx.stability().local_stability(id) + }; + providers.lookup_const_stability = |tcx, id| { + let id = tcx.hir().local_def_id_to_hir_id(id.expect_local()); + tcx.stability().local_const_stability(id) + }; + providers.lookup_deprecation_entry = |tcx, id| { + let id = tcx.hir().local_def_id_to_hir_id(id.expect_local()); + tcx.stability().local_deprecation_entry(id) + }; + providers.extern_mod_stmt_cnum = |tcx, id| tcx.extern_crate_map.get(&id).cloned(); + providers.all_crate_nums = |tcx, cnum| { + assert_eq!(cnum, LOCAL_CRATE); + tcx.arena.alloc_slice(&tcx.cstore.crates_untracked()) + }; + providers.output_filenames = |tcx, cnum| { + assert_eq!(cnum, LOCAL_CRATE); + tcx.output_filenames.clone() + }; + providers.features_query = |tcx, cnum| { + assert_eq!(cnum, LOCAL_CRATE); + tcx.sess.features_untracked() + }; + providers.is_panic_runtime = |tcx, cnum| { + assert_eq!(cnum, LOCAL_CRATE); + tcx.sess.contains_name(tcx.hir().krate_attrs(), sym::panic_runtime) + }; + providers.is_compiler_builtins = |tcx, cnum| { + assert_eq!(cnum, LOCAL_CRATE); + tcx.sess.contains_name(tcx.hir().krate_attrs(), sym::compiler_builtins) + }; + providers.has_panic_handler = |tcx, cnum| { + assert_eq!(cnum, LOCAL_CRATE); + // We want to check if the panic handler was defined in this crate + tcx.lang_items().panic_impl().map_or(false, |did| did.is_local()) + }; +} diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs new file mode 100644 index 00000000000..b22727bdd75 --- /dev/null +++ b/compiler/rustc_middle/src/ty/diagnostics.rs @@ -0,0 +1,270 @@ +//! Diagnostics related methods for `TyS`. + +use crate::ty::sty::InferTy; +use crate::ty::TyKind::*; +use crate::ty::{TyCtxt, TyS}; +use rustc_errors::{Applicability, DiagnosticBuilder}; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_hir::{QPath, TyKind, WhereBoundPredicate, WherePredicate}; + +impl<'tcx> TyS<'tcx> { + /// Similar to `TyS::is_primitive`, but also considers inferred numeric values to be primitive. + pub fn is_primitive_ty(&self) -> bool { + match self.kind { + Bool + | Char + | Str + | Int(_) + | Uint(_) + | Float(_) + | Infer( + InferTy::IntVar(_) + | InferTy::FloatVar(_) + | InferTy::FreshIntTy(_) + | InferTy::FreshFloatTy(_), + ) => true, + _ => false, + } + } + + /// Whether the type is succinctly representable as a type instead of just referred to with a + /// description in error messages. This is used in the main error message. + pub fn is_simple_ty(&self) -> bool { + match self.kind { + Bool + | Char + | Str + | Int(_) + | Uint(_) + | Float(_) + | Infer( + InferTy::IntVar(_) + | InferTy::FloatVar(_) + | InferTy::FreshIntTy(_) + | InferTy::FreshFloatTy(_), + ) => true, + Ref(_, x, _) | Array(x, _) | Slice(x) => x.peel_refs().is_simple_ty(), + Tuple(tys) if tys.is_empty() => true, + _ => false, + } + } + + /// Whether the type is succinctly representable as a type instead of just referred to with a + /// description in error messages. This is used in the primary span label. Beyond what + /// `is_simple_ty` includes, it also accepts ADTs with no type arguments and references to + /// ADTs with no type arguments. + pub fn is_simple_text(&self) -> bool { + match self.kind { + Adt(_, substs) => substs.types().next().is_none(), + Ref(_, ty, _) => ty.is_simple_text(), + _ => self.is_simple_ty(), + } + } + + /// Whether the type can be safely suggested during error recovery. + pub fn is_suggestable(&self) -> bool { + match self.kind { + Opaque(..) | FnDef(..) | FnPtr(..) | Dynamic(..) | Closure(..) | Infer(..) + | Projection(..) => false, + _ => true, + } + } +} + +/// Suggest restricting a type param with a new bound. +pub fn suggest_constraining_type_param( + tcx: TyCtxt<'_>, + generics: &hir::Generics<'_>, + err: &mut DiagnosticBuilder<'_>, + param_name: &str, + constraint: &str, + def_id: Option<DefId>, +) -> bool { + let param = generics.params.iter().find(|p| p.name.ident().as_str() == param_name); + + let param = if let Some(param) = param { + param + } else { + return false; + }; + + const MSG_RESTRICT_BOUND_FURTHER: &str = "consider further restricting this bound"; + let msg_restrict_type = format!("consider restricting type parameter `{}`", param_name); + let msg_restrict_type_further = + format!("consider further restricting type parameter `{}`", param_name); + + if def_id == tcx.lang_items().sized_trait() { + // Type parameters are already `Sized` by default. + err.span_label(param.span, &format!("this type parameter needs to be `{}`", constraint)); + return true; + } + let mut suggest_restrict = |span| { + err.span_suggestion_verbose( + span, + MSG_RESTRICT_BOUND_FURTHER, + format!(" + {}", constraint), + Applicability::MachineApplicable, + ); + }; + + if param_name.starts_with("impl ") { + // If there's an `impl Trait` used in argument position, suggest + // restricting it: + // + // fn foo(t: impl Foo) { ... } + // -------- + // | + // help: consider further restricting this bound with `+ Bar` + // + // Suggestion for tools in this case is: + // + // fn foo(t: impl Foo) { ... } + // -------- + // | + // replace with: `impl Foo + Bar` + + suggest_restrict(param.span.shrink_to_hi()); + return true; + } + + if generics.where_clause.predicates.is_empty() + // Given `trait Base<T = String>: Super<T>` where `T: Copy`, suggest restricting in the + // `where` clause instead of `trait Base<T: Copy = String>: Super<T>`. + && !matches!(param.kind, hir::GenericParamKind::Type { default: Some(_), .. }) + { + if let Some(bounds_span) = param.bounds_span() { + // If user has provided some bounds, suggest restricting them: + // + // fn foo<T: Foo>(t: T) { ... } + // --- + // | + // help: consider further restricting this bound with `+ Bar` + // + // Suggestion for tools in this case is: + // + // fn foo<T: Foo>(t: T) { ... } + // -- + // | + // replace with: `T: Bar +` + suggest_restrict(bounds_span.shrink_to_hi()); + } else { + // If user hasn't provided any bounds, suggest adding a new one: + // + // fn foo<T>(t: T) { ... } + // - help: consider restricting this type parameter with `T: Foo` + err.span_suggestion_verbose( + param.span.shrink_to_hi(), + &msg_restrict_type, + format!(": {}", constraint), + Applicability::MachineApplicable, + ); + } + + true + } else { + // This part is a bit tricky, because using the `where` clause user can + // provide zero, one or many bounds for the same type parameter, so we + // have following cases to consider: + // + // 1) When the type parameter has been provided zero bounds + // + // Message: + // fn foo<X, Y>(x: X, y: Y) where Y: Foo { ... } + // - help: consider restricting this type parameter with `where X: Bar` + // + // Suggestion: + // fn foo<X, Y>(x: X, y: Y) where Y: Foo { ... } + // - insert: `, X: Bar` + // + // + // 2) When the type parameter has been provided one bound + // + // Message: + // fn foo<T>(t: T) where T: Foo { ... } + // ^^^^^^ + // | + // help: consider further restricting this bound with `+ Bar` + // + // Suggestion: + // fn foo<T>(t: T) where T: Foo { ... } + // ^^ + // | + // replace with: `T: Bar +` + // + // + // 3) When the type parameter has been provided many bounds + // + // Message: + // fn foo<T>(t: T) where T: Foo, T: Bar {... } + // - help: consider further restricting this type parameter with `where T: Zar` + // + // Suggestion: + // fn foo<T>(t: T) where T: Foo, T: Bar {... } + // - insert: `, T: Zar` + + let mut param_spans = Vec::new(); + + for predicate in generics.where_clause.predicates { + if let WherePredicate::BoundPredicate(WhereBoundPredicate { + span, bounded_ty, .. + }) = predicate + { + if let TyKind::Path(QPath::Resolved(_, path)) = &bounded_ty.kind { + if let Some(segment) = path.segments.first() { + if segment.ident.to_string() == param_name { + param_spans.push(span); + } + } + } + } + } + + match ¶m_spans[..] { + &[¶m_span] => suggest_restrict(param_span.shrink_to_hi()), + _ => { + err.span_suggestion_verbose( + generics.where_clause.tail_span_for_suggestion(), + &msg_restrict_type_further, + format!(", {}: {}", param_name, constraint), + Applicability::MachineApplicable, + ); + } + } + + true + } +} + +/// Collect al types that have an implicit `'static` obligation that we could suggest `'_` for. +pub struct TraitObjectVisitor<'tcx>(pub Vec<&'tcx hir::Ty<'tcx>>, pub crate::hir::map::Map<'tcx>); + +impl<'v> hir::intravisit::Visitor<'v> for TraitObjectVisitor<'v> { + type Map = rustc_hir::intravisit::ErasedMap<'v>; + + fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> { + hir::intravisit::NestedVisitorMap::None + } + + fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) { + match ty.kind { + hir::TyKind::TraitObject( + _, + hir::Lifetime { + name: + hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Static, + .. + }, + ) => { + self.0.push(ty); + } + hir::TyKind::OpaqueDef(item_id, _) => { + self.0.push(ty); + let item = self.1.expect_item(item_id.id); + hir::intravisit::walk_item(self, item); + } + _ => {} + } + hir::intravisit::walk_ty(self, ty); + } +} diff --git a/compiler/rustc_middle/src/ty/erase_regions.rs b/compiler/rustc_middle/src/ty/erase_regions.rs new file mode 100644 index 00000000000..48d0fc1839e --- /dev/null +++ b/compiler/rustc_middle/src/ty/erase_regions.rs @@ -0,0 +1,68 @@ +use crate::ty::fold::{TypeFoldable, TypeFolder}; +use crate::ty::{self, Ty, TyCtxt, TypeFlags}; + +pub(super) fn provide(providers: &mut ty::query::Providers) { + *providers = ty::query::Providers { erase_regions_ty, ..*providers }; +} + +fn erase_regions_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> { + // N.B., use `super_fold_with` here. If we used `fold_with`, it + // could invoke the `erase_regions_ty` query recursively. + ty.super_fold_with(&mut RegionEraserVisitor { tcx }) +} + +impl<'tcx> TyCtxt<'tcx> { + /// Returns an equivalent value with all free regions removed (note + /// that late-bound regions remain, because they are important for + /// subtyping, but they are anonymized and normalized as well).. + pub fn erase_regions<T>(self, value: &T) -> T + where + T: TypeFoldable<'tcx>, + { + // If there's nothing to erase avoid performing the query at all + if !value.has_type_flags(TypeFlags::HAS_RE_LATE_BOUND | TypeFlags::HAS_FREE_REGIONS) { + return value.clone(); + } + + let value1 = value.fold_with(&mut RegionEraserVisitor { tcx: self }); + debug!("erase_regions({:?}) = {:?}", value, value1); + value1 + } +} + +struct RegionEraserVisitor<'tcx> { + tcx: TyCtxt<'tcx>, +} + +impl TypeFolder<'tcx> for RegionEraserVisitor<'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { + if ty.needs_infer() { ty.super_fold_with(self) } else { self.tcx.erase_regions_ty(ty) } + } + + fn fold_binder<T>(&mut self, t: &ty::Binder<T>) -> ty::Binder<T> + where + T: TypeFoldable<'tcx>, + { + let u = self.tcx.anonymize_late_bound_regions(t); + u.super_fold_with(self) + } + + fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { + // because late-bound regions affect subtyping, we can't + // erase the bound/free distinction, but we can replace + // all free regions with 'erased. + // + // Note that we *CAN* replace early-bound regions -- the + // type system never "sees" those, they get substituted + // away. In codegen, they will always be erased to 'erased + // whenever a substitution occurs. + match *r { + ty::ReLateBound(..) => r, + _ => self.tcx.lifetimes.re_erased, + } + } +} diff --git a/compiler/rustc_middle/src/ty/error.rs b/compiler/rustc_middle/src/ty/error.rs new file mode 100644 index 00000000000..1963881626e --- /dev/null +++ b/compiler/rustc_middle/src/ty/error.rs @@ -0,0 +1,897 @@ +use crate::traits::{ObligationCause, ObligationCauseCode}; +use crate::ty::diagnostics::suggest_constraining_type_param; +use crate::ty::{self, BoundRegion, Region, Ty, TyCtxt}; +use rustc_ast as ast; +use rustc_errors::Applicability::{MachineApplicable, MaybeIncorrect}; +use rustc_errors::{pluralize, DiagnosticBuilder}; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_span::symbol::{sym, Symbol}; +use rustc_span::{BytePos, MultiSpan, Span}; +use rustc_target::spec::abi; + +use std::borrow::Cow; +use std::fmt; +use std::ops::Deref; + +#[derive(Clone, Copy, Debug, PartialEq, Eq, TypeFoldable)] +pub struct ExpectedFound<T> { + pub expected: T, + pub found: T, +} + +impl<T> ExpectedFound<T> { + pub fn new(a_is_expected: bool, a: T, b: T) -> Self { + if a_is_expected { + ExpectedFound { expected: a, found: b } + } else { + ExpectedFound { expected: b, found: a } + } + } +} + +// Data structures used in type unification +#[derive(Clone, Debug, TypeFoldable)] +pub enum TypeError<'tcx> { + Mismatch, + UnsafetyMismatch(ExpectedFound<hir::Unsafety>), + AbiMismatch(ExpectedFound<abi::Abi>), + Mutability, + TupleSize(ExpectedFound<usize>), + FixedArraySize(ExpectedFound<u64>), + ArgCount, + + RegionsDoesNotOutlive(Region<'tcx>, Region<'tcx>), + RegionsInsufficientlyPolymorphic(BoundRegion, Region<'tcx>), + RegionsOverlyPolymorphic(BoundRegion, Region<'tcx>), + RegionsPlaceholderMismatch, + + Sorts(ExpectedFound<Ty<'tcx>>), + IntMismatch(ExpectedFound<ty::IntVarValue>), + FloatMismatch(ExpectedFound<ast::FloatTy>), + Traits(ExpectedFound<DefId>), + VariadicMismatch(ExpectedFound<bool>), + + /// Instantiating a type variable with the given type would have + /// created a cycle (because it appears somewhere within that + /// type). + CyclicTy(Ty<'tcx>), + ProjectionMismatched(ExpectedFound<DefId>), + ExistentialMismatch(ExpectedFound<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>), + ObjectUnsafeCoercion(DefId), + ConstMismatch(ExpectedFound<&'tcx ty::Const<'tcx>>), + + IntrinsicCast, + /// Safe `#[target_feature]` functions are not assignable to safe function pointers. + TargetFeatureCast(DefId), +} + +pub enum UnconstrainedNumeric { + UnconstrainedFloat, + UnconstrainedInt, + Neither, +} + +/// Explains the source of a type err in a short, human readable way. This is meant to be placed +/// in parentheses after some larger message. You should also invoke `note_and_explain_type_err()` +/// afterwards to present additional details, particularly when it comes to lifetime-related +/// errors. +impl<'tcx> fmt::Display for TypeError<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + use self::TypeError::*; + fn report_maybe_different( + f: &mut fmt::Formatter<'_>, + expected: &str, + found: &str, + ) -> fmt::Result { + // A naive approach to making sure that we're not reporting silly errors such as: + // (expected closure, found closure). + if expected == found { + write!(f, "expected {}, found a different {}", expected, found) + } else { + write!(f, "expected {}, found {}", expected, found) + } + } + + let br_string = |br: ty::BoundRegion| match br { + ty::BrNamed(_, name) => format!(" {}", name), + _ => String::new(), + }; + + match *self { + CyclicTy(_) => write!(f, "cyclic type of infinite size"), + Mismatch => write!(f, "types differ"), + UnsafetyMismatch(values) => { + write!(f, "expected {} fn, found {} fn", values.expected, values.found) + } + AbiMismatch(values) => { + write!(f, "expected {} fn, found {} fn", values.expected, values.found) + } + Mutability => write!(f, "types differ in mutability"), + TupleSize(values) => write!( + f, + "expected a tuple with {} element{}, \ + found one with {} element{}", + values.expected, + pluralize!(values.expected), + values.found, + pluralize!(values.found) + ), + FixedArraySize(values) => write!( + f, + "expected an array with a fixed size of {} element{}, \ + found one with {} element{}", + values.expected, + pluralize!(values.expected), + values.found, + pluralize!(values.found) + ), + ArgCount => write!(f, "incorrect number of function parameters"), + RegionsDoesNotOutlive(..) => write!(f, "lifetime mismatch"), + RegionsInsufficientlyPolymorphic(br, _) => write!( + f, + "expected bound lifetime parameter{}, found concrete lifetime", + br_string(br) + ), + RegionsOverlyPolymorphic(br, _) => write!( + f, + "expected concrete lifetime, found bound lifetime parameter{}", + br_string(br) + ), + RegionsPlaceholderMismatch => write!(f, "one type is more general than the other"), + Sorts(values) => ty::tls::with(|tcx| { + report_maybe_different( + f, + &values.expected.sort_string(tcx), + &values.found.sort_string(tcx), + ) + }), + Traits(values) => ty::tls::with(|tcx| { + report_maybe_different( + f, + &format!("trait `{}`", tcx.def_path_str(values.expected)), + &format!("trait `{}`", tcx.def_path_str(values.found)), + ) + }), + IntMismatch(ref values) => { + write!(f, "expected `{:?}`, found `{:?}`", values.expected, values.found) + } + FloatMismatch(ref values) => { + write!(f, "expected `{:?}`, found `{:?}`", values.expected, values.found) + } + VariadicMismatch(ref values) => write!( + f, + "expected {} fn, found {} function", + if values.expected { "variadic" } else { "non-variadic" }, + if values.found { "variadic" } else { "non-variadic" } + ), + ProjectionMismatched(ref values) => ty::tls::with(|tcx| { + write!( + f, + "expected {}, found {}", + tcx.def_path_str(values.expected), + tcx.def_path_str(values.found) + ) + }), + ExistentialMismatch(ref values) => report_maybe_different( + f, + &format!("trait `{}`", values.expected), + &format!("trait `{}`", values.found), + ), + ConstMismatch(ref values) => { + write!(f, "expected `{}`, found `{}`", values.expected, values.found) + } + IntrinsicCast => write!(f, "cannot coerce intrinsics to function pointers"), + TargetFeatureCast(_) => write!( + f, + "cannot coerce functions with `#[target_feature]` to safe function pointers" + ), + ObjectUnsafeCoercion(_) => write!(f, "coercion to object-unsafe trait object"), + } + } +} + +impl<'tcx> TypeError<'tcx> { + pub fn must_include_note(&self) -> bool { + use self::TypeError::*; + match self { + CyclicTy(_) | UnsafetyMismatch(_) | Mismatch | AbiMismatch(_) | FixedArraySize(_) + | Sorts(_) | IntMismatch(_) | FloatMismatch(_) | VariadicMismatch(_) + | TargetFeatureCast(_) => false, + + Mutability + | TupleSize(_) + | ArgCount + | RegionsDoesNotOutlive(..) + | RegionsInsufficientlyPolymorphic(..) + | RegionsOverlyPolymorphic(..) + | RegionsPlaceholderMismatch + | Traits(_) + | ProjectionMismatched(_) + | ExistentialMismatch(_) + | ConstMismatch(_) + | IntrinsicCast + | ObjectUnsafeCoercion(_) => true, + } + } +} + +impl<'tcx> ty::TyS<'tcx> { + pub fn sort_string(&self, tcx: TyCtxt<'_>) -> Cow<'static, str> { + match self.kind { + ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str | ty::Never => { + format!("`{}`", self).into() + } + ty::Tuple(ref tys) if tys.is_empty() => format!("`{}`", self).into(), + + ty::Adt(def, _) => format!("{} `{}`", def.descr(), tcx.def_path_str(def.did)).into(), + ty::Foreign(def_id) => format!("extern type `{}`", tcx.def_path_str(def_id)).into(), + ty::Array(t, n) => { + let n = tcx.lift(&n).unwrap(); + match n.try_eval_usize(tcx, ty::ParamEnv::empty()) { + _ if t.is_simple_ty() => format!("array `{}`", self).into(), + Some(n) => format!("array of {} element{} ", n, pluralize!(n)).into(), + None => "array".into(), + } + } + ty::Slice(ty) if ty.is_simple_ty() => format!("slice `{}`", self).into(), + ty::Slice(_) => "slice".into(), + ty::RawPtr(_) => "*-ptr".into(), + ty::Ref(_, ty, mutbl) => { + let tymut = ty::TypeAndMut { ty, mutbl }; + let tymut_string = tymut.to_string(); + if tymut_string != "_" + && (ty.is_simple_text() || tymut_string.len() < "mutable reference".len()) + { + format!("`&{}`", tymut_string).into() + } else { + // Unknown type name, it's long or has type arguments + match mutbl { + hir::Mutability::Mut => "mutable reference", + _ => "reference", + } + .into() + } + } + ty::FnDef(..) => "fn item".into(), + ty::FnPtr(_) => "fn pointer".into(), + ty::Dynamic(ref inner, ..) => { + if let Some(principal) = inner.principal() { + format!("trait object `dyn {}`", tcx.def_path_str(principal.def_id())).into() + } else { + "trait object".into() + } + } + ty::Closure(..) => "closure".into(), + ty::Generator(..) => "generator".into(), + ty::GeneratorWitness(..) => "generator witness".into(), + ty::Tuple(..) => "tuple".into(), + ty::Infer(ty::TyVar(_)) => "inferred type".into(), + ty::Infer(ty::IntVar(_)) => "integer".into(), + ty::Infer(ty::FloatVar(_)) => "floating-point number".into(), + ty::Placeholder(..) => "placeholder type".into(), + ty::Bound(..) => "bound type".into(), + ty::Infer(ty::FreshTy(_)) => "fresh type".into(), + ty::Infer(ty::FreshIntTy(_)) => "fresh integral type".into(), + ty::Infer(ty::FreshFloatTy(_)) => "fresh floating-point type".into(), + ty::Projection(_) => "associated type".into(), + ty::Param(p) => format!("type parameter `{}`", p).into(), + ty::Opaque(..) => "opaque type".into(), + ty::Error(_) => "type error".into(), + } + } + + pub fn prefix_string(&self) -> Cow<'static, str> { + match self.kind { + ty::Infer(_) + | ty::Error(_) + | ty::Bool + | ty::Char + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Str + | ty::Never => "type".into(), + ty::Tuple(ref tys) if tys.is_empty() => "unit type".into(), + ty::Adt(def, _) => def.descr().into(), + ty::Foreign(_) => "extern type".into(), + ty::Array(..) => "array".into(), + ty::Slice(_) => "slice".into(), + ty::RawPtr(_) => "raw pointer".into(), + ty::Ref(.., mutbl) => match mutbl { + hir::Mutability::Mut => "mutable reference", + _ => "reference", + } + .into(), + ty::FnDef(..) => "fn item".into(), + ty::FnPtr(_) => "fn pointer".into(), + ty::Dynamic(..) => "trait object".into(), + ty::Closure(..) => "closure".into(), + ty::Generator(..) => "generator".into(), + ty::GeneratorWitness(..) => "generator witness".into(), + ty::Tuple(..) => "tuple".into(), + ty::Placeholder(..) => "higher-ranked type".into(), + ty::Bound(..) => "bound type variable".into(), + ty::Projection(_) => "associated type".into(), + ty::Param(_) => "type parameter".into(), + ty::Opaque(..) => "opaque type".into(), + } + } +} + +impl<'tcx> TyCtxt<'tcx> { + pub fn note_and_explain_type_err( + self, + db: &mut DiagnosticBuilder<'_>, + err: &TypeError<'tcx>, + cause: &ObligationCause<'tcx>, + sp: Span, + body_owner_def_id: DefId, + ) { + use self::TypeError::*; + debug!("note_and_explain_type_err err={:?} cause={:?}", err, cause); + match err { + Sorts(values) => { + let expected_str = values.expected.sort_string(self); + let found_str = values.found.sort_string(self); + if expected_str == found_str && expected_str == "closure" { + db.note("no two closures, even if identical, have the same type"); + db.help("consider boxing your closure and/or using it as a trait object"); + } + if expected_str == found_str && expected_str == "opaque type" { + // Issue #63167 + db.note("distinct uses of `impl Trait` result in different opaque types"); + let e_str = values.expected.to_string(); + let f_str = values.found.to_string(); + if e_str == f_str && &e_str == "impl std::future::Future" { + // FIXME: use non-string based check. + db.help( + "if both `Future`s have the same `Output` type, consider \ + `.await`ing on both of them", + ); + } + } + match (&values.expected.kind, &values.found.kind) { + (ty::Float(_), ty::Infer(ty::IntVar(_))) => { + if let Ok( + // Issue #53280 + snippet, + ) = self.sess.source_map().span_to_snippet(sp) + { + if snippet.chars().all(|c| c.is_digit(10) || c == '-' || c == '_') { + db.span_suggestion( + sp, + "use a float literal", + format!("{}.0", snippet), + MachineApplicable, + ); + } + } + } + (ty::Param(expected), ty::Param(found)) => { + let generics = self.generics_of(body_owner_def_id); + let e_span = self.def_span(generics.type_param(expected, self).def_id); + if !sp.contains(e_span) { + db.span_label(e_span, "expected type parameter"); + } + let f_span = self.def_span(generics.type_param(found, self).def_id); + if !sp.contains(f_span) { + db.span_label(f_span, "found type parameter"); + } + db.note( + "a type parameter was expected, but a different one was found; \ + you might be missing a type parameter or trait bound", + ); + db.note( + "for more information, visit \ + https://doc.rust-lang.org/book/ch10-02-traits.html\ + #traits-as-parameters", + ); + } + (ty::Projection(_), ty::Projection(_)) => { + db.note("an associated type was expected, but a different one was found"); + } + (ty::Param(p), ty::Projection(proj)) | (ty::Projection(proj), ty::Param(p)) => { + let generics = self.generics_of(body_owner_def_id); + let p_span = self.def_span(generics.type_param(p, self).def_id); + if !sp.contains(p_span) { + db.span_label(p_span, "this type parameter"); + } + let hir = self.hir(); + let mut note = true; + if let Some(generics) = generics + .type_param(p, self) + .def_id + .as_local() + .map(|id| hir.local_def_id_to_hir_id(id)) + .and_then(|id| self.hir().find(self.hir().get_parent_node(id))) + .as_ref() + .and_then(|node| node.generics()) + { + // Synthesize the associated type restriction `Add<Output = Expected>`. + // FIXME: extract this logic for use in other diagnostics. + let trait_ref = proj.trait_ref(self); + let path = + self.def_path_str_with_substs(trait_ref.def_id, trait_ref.substs); + let item_name = self.item_name(proj.item_def_id); + let path = if path.ends_with('>') { + format!("{}, {} = {}>", &path[..path.len() - 1], item_name, p) + } else { + format!("{}<{} = {}>", path, item_name, p) + }; + note = !suggest_constraining_type_param( + self, + generics, + db, + &format!("{}", proj.self_ty()), + &path, + None, + ); + } + if note { + db.note("you might be missing a type parameter or trait bound"); + } + } + (ty::Param(p), ty::Dynamic(..) | ty::Opaque(..)) + | (ty::Dynamic(..) | ty::Opaque(..), ty::Param(p)) => { + let generics = self.generics_of(body_owner_def_id); + let p_span = self.def_span(generics.type_param(p, self).def_id); + if !sp.contains(p_span) { + db.span_label(p_span, "this type parameter"); + } + db.help("type parameters must be constrained to match other types"); + if self.sess.teach(&db.get_code().unwrap()) { + db.help( + "given a type parameter `T` and a method `foo`: +``` +trait Trait<T> { fn foo(&self) -> T; } +``` +the only ways to implement method `foo` are: +- constrain `T` with an explicit type: +``` +impl Trait<String> for X { + fn foo(&self) -> String { String::new() } +} +``` +- add a trait bound to `T` and call a method on that trait that returns `Self`: +``` +impl<T: std::default::Default> Trait<T> for X { + fn foo(&self) -> T { <T as std::default::Default>::default() } +} +``` +- change `foo` to return an argument of type `T`: +``` +impl<T> Trait<T> for X { + fn foo(&self, x: T) -> T { x } +} +```", + ); + } + db.note( + "for more information, visit \ + https://doc.rust-lang.org/book/ch10-02-traits.html\ + #traits-as-parameters", + ); + } + (ty::Param(p), _) | (_, ty::Param(p)) => { + let generics = self.generics_of(body_owner_def_id); + let p_span = self.def_span(generics.type_param(p, self).def_id); + if !sp.contains(p_span) { + db.span_label(p_span, "this type parameter"); + } + } + (ty::Projection(proj_ty), _) => { + self.expected_projection( + db, + proj_ty, + values, + body_owner_def_id, + &cause.code, + ); + } + (_, ty::Projection(proj_ty)) => { + let msg = format!( + "consider constraining the associated type `{}` to `{}`", + values.found, values.expected, + ); + if !self.suggest_constraint( + db, + &msg, + body_owner_def_id, + proj_ty, + values.expected, + ) { + db.help(&msg); + db.note( + "for more information, visit \ + https://doc.rust-lang.org/book/ch19-03-advanced-traits.html", + ); + } + } + _ => {} + } + debug!( + "note_and_explain_type_err expected={:?} ({:?}) found={:?} ({:?})", + values.expected, values.expected.kind, values.found, values.found.kind, + ); + } + CyclicTy(ty) => { + // Watch out for various cases of cyclic types and try to explain. + if ty.is_closure() || ty.is_generator() { + db.note( + "closures cannot capture themselves or take themselves as argument;\n\ + this error may be the result of a recent compiler bug-fix,\n\ + see issue #46062 <https://github.com/rust-lang/rust/issues/46062>\n\ + for more information", + ); + } + } + TargetFeatureCast(def_id) => { + let attrs = self.get_attrs(*def_id); + let target_spans = attrs + .deref() + .iter() + .filter(|attr| attr.has_name(sym::target_feature)) + .map(|attr| attr.span); + db.note( + "functions with `#[target_feature]` can only be coerced to `unsafe` function pointers" + ); + db.span_labels(target_spans, "`#[target_feature]` added here"); + } + _ => {} + } + } + + fn suggest_constraint( + &self, + db: &mut DiagnosticBuilder<'_>, + msg: &str, + body_owner_def_id: DefId, + proj_ty: &ty::ProjectionTy<'tcx>, + ty: Ty<'tcx>, + ) -> bool { + let assoc = self.associated_item(proj_ty.item_def_id); + let trait_ref = proj_ty.trait_ref(*self); + if let Some(item) = self.hir().get_if_local(body_owner_def_id) { + if let Some(hir_generics) = item.generics() { + // Get the `DefId` for the type parameter corresponding to `A` in `<A as T>::Foo`. + // This will also work for `impl Trait`. + let def_id = if let ty::Param(param_ty) = proj_ty.self_ty().kind { + let generics = self.generics_of(body_owner_def_id); + generics.type_param(¶m_ty, *self).def_id + } else { + return false; + }; + + // First look in the `where` clause, as this might be + // `fn foo<T>(x: T) where T: Trait`. + for predicate in hir_generics.where_clause.predicates { + if let hir::WherePredicate::BoundPredicate(pred) = predicate { + if let hir::TyKind::Path(hir::QPath::Resolved(None, path)) = + pred.bounded_ty.kind + { + if path.res.opt_def_id() == Some(def_id) { + // This predicate is binding type param `A` in `<A as T>::Foo` to + // something, potentially `T`. + } else { + continue; + } + } else { + continue; + } + + if self.constrain_generic_bound_associated_type_structured_suggestion( + db, + &trait_ref, + pred.bounds, + &assoc, + ty, + msg, + ) { + return true; + } + } + } + for param in hir_generics.params { + if self.hir().opt_local_def_id(param.hir_id).map(|id| id.to_def_id()) + == Some(def_id) + { + // This is type param `A` in `<A as T>::Foo`. + return self.constrain_generic_bound_associated_type_structured_suggestion( + db, + &trait_ref, + param.bounds, + &assoc, + ty, + msg, + ); + } + } + } + } + false + } + + /// An associated type was expected and a different type was found. + /// + /// We perform a few different checks to see what we can suggest: + /// + /// - In the current item, look for associated functions that return the expected type and + /// suggest calling them. (Not a structured suggestion.) + /// - If any of the item's generic bounds can be constrained, we suggest constraining the + /// associated type to the found type. + /// - If the associated type has a default type and was expected inside of a `trait`, we + /// mention that this is disallowed. + /// - If all other things fail, and the error is not because of a mismatch between the `trait` + /// and the `impl`, we provide a generic `help` to constrain the assoc type or call an assoc + /// fn that returns the type. + fn expected_projection( + &self, + db: &mut DiagnosticBuilder<'_>, + proj_ty: &ty::ProjectionTy<'tcx>, + values: &ExpectedFound<Ty<'tcx>>, + body_owner_def_id: DefId, + cause_code: &ObligationCauseCode<'_>, + ) { + let msg = format!( + "consider constraining the associated type `{}` to `{}`", + values.expected, values.found + ); + let body_owner = self.hir().get_if_local(body_owner_def_id); + let current_method_ident = body_owner.and_then(|n| n.ident()).map(|i| i.name); + + // We don't want to suggest calling an assoc fn in a scope where that isn't feasible. + let callable_scope = match body_owner { + Some( + hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(..), .. }) + | hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. }) + | hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }), + ) => true, + _ => false, + }; + let impl_comparison = matches!( + cause_code, + ObligationCauseCode::CompareImplMethodObligation { .. } + | ObligationCauseCode::CompareImplTypeObligation { .. } + | ObligationCauseCode::CompareImplConstObligation + ); + let assoc = self.associated_item(proj_ty.item_def_id); + if !callable_scope || impl_comparison { + // We do not want to suggest calling functions when the reason of the + // type error is a comparison of an `impl` with its `trait` or when the + // scope is outside of a `Body`. + } else { + // If we find a suitable associated function that returns the expected type, we don't + // want the more general suggestion later in this method about "consider constraining + // the associated type or calling a method that returns the associated type". + let point_at_assoc_fn = self.point_at_methods_that_satisfy_associated_type( + db, + assoc.container.id(), + current_method_ident, + proj_ty.item_def_id, + values.expected, + ); + // Possibly suggest constraining the associated type to conform to the + // found type. + if self.suggest_constraint(db, &msg, body_owner_def_id, proj_ty, values.found) + || point_at_assoc_fn + { + return; + } + } + + if let ty::Opaque(def_id, _) = proj_ty.self_ty().kind { + // When the expected `impl Trait` is not defined in the current item, it will come from + // a return type. This can occur when dealing with `TryStream` (#71035). + if self.constrain_associated_type_structured_suggestion( + db, + self.def_span(def_id), + &assoc, + values.found, + &msg, + ) { + return; + } + } + + if self.point_at_associated_type(db, body_owner_def_id, values.found) { + return; + } + + if !impl_comparison { + // Generic suggestion when we can't be more specific. + if callable_scope { + db.help(&format!("{} or calling a method that returns `{}`", msg, values.expected)); + } else { + db.help(&msg); + } + db.note( + "for more information, visit \ + https://doc.rust-lang.org/book/ch19-03-advanced-traits.html", + ); + } + if self.sess.teach(&db.get_code().unwrap()) { + db.help( + "given an associated type `T` and a method `foo`: +``` +trait Trait { +type T; +fn foo(&self) -> Self::T; +} +``` +the only way of implementing method `foo` is to constrain `T` with an explicit associated type: +``` +impl Trait for X { +type T = String; +fn foo(&self) -> Self::T { String::new() } +} +```", + ); + } + } + + fn point_at_methods_that_satisfy_associated_type( + &self, + db: &mut DiagnosticBuilder<'_>, + assoc_container_id: DefId, + current_method_ident: Option<Symbol>, + proj_ty_item_def_id: DefId, + expected: Ty<'tcx>, + ) -> bool { + let items = self.associated_items(assoc_container_id); + // Find all the methods in the trait that could be called to construct the + // expected associated type. + // FIXME: consider suggesting the use of associated `const`s. + let methods: Vec<(Span, String)> = items + .items + .iter() + .filter(|(name, item)| { + ty::AssocKind::Fn == item.kind && Some(**name) != current_method_ident + }) + .filter_map(|(_, item)| { + let method = self.fn_sig(item.def_id); + match method.output().skip_binder().kind { + ty::Projection(ty::ProjectionTy { item_def_id, .. }) + if item_def_id == proj_ty_item_def_id => + { + Some(( + self.sess.source_map().guess_head_span(self.def_span(item.def_id)), + format!("consider calling `{}`", self.def_path_str(item.def_id)), + )) + } + _ => None, + } + }) + .collect(); + if !methods.is_empty() { + // Use a single `help:` to show all the methods in the trait that can + // be used to construct the expected associated type. + let mut span: MultiSpan = + methods.iter().map(|(sp, _)| *sp).collect::<Vec<Span>>().into(); + let msg = format!( + "{some} method{s} {are} available that return{r} `{ty}`", + some = if methods.len() == 1 { "a" } else { "some" }, + s = pluralize!(methods.len()), + are = if methods.len() == 1 { "is" } else { "are" }, + r = if methods.len() == 1 { "s" } else { "" }, + ty = expected + ); + for (sp, label) in methods.into_iter() { + span.push_span_label(sp, label); + } + db.span_help(span, &msg); + return true; + } + false + } + + fn point_at_associated_type( + &self, + db: &mut DiagnosticBuilder<'_>, + body_owner_def_id: DefId, + found: Ty<'tcx>, + ) -> bool { + let hir_id = + match body_owner_def_id.as_local().map(|id| self.hir().local_def_id_to_hir_id(id)) { + Some(hir_id) => hir_id, + None => return false, + }; + // When `body_owner` is an `impl` or `trait` item, look in its associated types for + // `expected` and point at it. + let parent_id = self.hir().get_parent_item(hir_id); + let item = self.hir().find(parent_id); + debug!("expected_projection parent item {:?}", item); + match item { + Some(hir::Node::Item(hir::Item { kind: hir::ItemKind::Trait(.., items), .. })) => { + // FIXME: account for `#![feature(specialization)]` + for item in &items[..] { + match item.kind { + hir::AssocItemKind::Type => { + // FIXME: account for returning some type in a trait fn impl that has + // an assoc type as a return type (#72076). + if let hir::Defaultness::Default { has_value: true } = item.defaultness + { + if self.type_of(self.hir().local_def_id(item.id.hir_id)) == found { + db.span_label( + item.span, + "associated type defaults can't be assumed inside the \ + trait defining them", + ); + return true; + } + } + } + _ => {} + } + } + } + Some(hir::Node::Item(hir::Item { + kind: hir::ItemKind::Impl { items, .. }, .. + })) => { + for item in &items[..] { + match item.kind { + hir::AssocItemKind::Type => { + if self.type_of(self.hir().local_def_id(item.id.hir_id)) == found { + db.span_label(item.span, "expected this associated type"); + return true; + } + } + _ => {} + } + } + } + _ => {} + } + false + } + + /// Given a slice of `hir::GenericBound`s, if any of them corresponds to the `trait_ref` + /// requirement, provide a strucuted suggestion to constrain it to a given type `ty`. + fn constrain_generic_bound_associated_type_structured_suggestion( + &self, + db: &mut DiagnosticBuilder<'_>, + trait_ref: &ty::TraitRef<'tcx>, + bounds: hir::GenericBounds<'_>, + assoc: &ty::AssocItem, + ty: Ty<'tcx>, + msg: &str, + ) -> bool { + // FIXME: we would want to call `resolve_vars_if_possible` on `ty` before suggesting. + bounds.iter().any(|bound| match bound { + hir::GenericBound::Trait(ptr, hir::TraitBoundModifier::None) => { + // Relate the type param against `T` in `<A as T>::Foo`. + ptr.trait_ref.trait_def_id() == Some(trait_ref.def_id) + && self.constrain_associated_type_structured_suggestion( + db, ptr.span, assoc, ty, msg, + ) + } + _ => false, + }) + } + + /// Given a span corresponding to a bound, provide a structured suggestion to set an + /// associated type to a given type `ty`. + fn constrain_associated_type_structured_suggestion( + &self, + db: &mut DiagnosticBuilder<'_>, + span: Span, + assoc: &ty::AssocItem, + ty: Ty<'tcx>, + msg: &str, + ) -> bool { + if let Ok(has_params) = + self.sess.source_map().span_to_snippet(span).map(|snippet| snippet.ends_with('>')) + { + let (span, sugg) = if has_params { + let pos = span.hi() - BytePos(1); + let span = Span::new(pos, pos, span.ctxt()); + (span, format!(", {} = {}", assoc.ident, ty)) + } else { + (span.shrink_to_hi(), format!("<{} = {}>", assoc.ident, ty)) + }; + db.span_suggestion_verbose(span, msg, sugg, MaybeIncorrect); + return true; + } + false + } +} diff --git a/compiler/rustc_middle/src/ty/fast_reject.rs b/compiler/rustc_middle/src/ty/fast_reject.rs new file mode 100644 index 00000000000..1bee2d60f75 --- /dev/null +++ b/compiler/rustc_middle/src/ty/fast_reject.rs @@ -0,0 +1,173 @@ +use crate::ich::StableHashingContext; +use crate::ty::{self, Ty, TyCtxt}; +use rustc_ast as ast; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_hir::def_id::DefId; +use std::fmt::Debug; +use std::hash::Hash; +use std::mem; + +use self::SimplifiedTypeGen::*; + +pub type SimplifiedType = SimplifiedTypeGen<DefId>; + +/// See `simplify_type` +/// +/// Note that we keep this type generic over the type of identifier it uses +/// because we sometimes need to use SimplifiedTypeGen values as stable sorting +/// keys (in which case we use a DefPathHash as id-type) but in the general case +/// the non-stable but fast to construct DefId-version is the better choice. +#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)] +pub enum SimplifiedTypeGen<D> +where + D: Copy + Debug + Ord + Eq, +{ + BoolSimplifiedType, + CharSimplifiedType, + IntSimplifiedType(ast::IntTy), + UintSimplifiedType(ast::UintTy), + FloatSimplifiedType(ast::FloatTy), + AdtSimplifiedType(D), + StrSimplifiedType, + ArraySimplifiedType, + PtrSimplifiedType, + NeverSimplifiedType, + TupleSimplifiedType(usize), + /// A trait object, all of whose components are markers + /// (e.g., `dyn Send + Sync`). + MarkerTraitObjectSimplifiedType, + TraitSimplifiedType(D), + ClosureSimplifiedType(D), + GeneratorSimplifiedType(D), + GeneratorWitnessSimplifiedType(usize), + OpaqueSimplifiedType(D), + FunctionSimplifiedType(usize), + ParameterSimplifiedType, + ForeignSimplifiedType(DefId), +} + +/// Tries to simplify a type by dropping type parameters, deref'ing away any reference types, etc. +/// The idea is to get something simple that we can use to quickly decide if two types could unify +/// during method lookup. +/// +/// If `can_simplify_params` is false, then we will fail to simplify type parameters entirely. This +/// is useful when those type parameters would be instantiated with fresh type variables, since +/// then we can't say much about whether two types would unify. Put another way, +/// `can_simplify_params` should be true if type parameters appear free in `ty` and `false` if they +/// are to be considered bound. +pub fn simplify_type( + tcx: TyCtxt<'_>, + ty: Ty<'_>, + can_simplify_params: bool, +) -> Option<SimplifiedType> { + match ty.kind { + ty::Bool => Some(BoolSimplifiedType), + ty::Char => Some(CharSimplifiedType), + ty::Int(int_type) => Some(IntSimplifiedType(int_type)), + ty::Uint(uint_type) => Some(UintSimplifiedType(uint_type)), + ty::Float(float_type) => Some(FloatSimplifiedType(float_type)), + ty::Adt(def, _) => Some(AdtSimplifiedType(def.did)), + ty::Str => Some(StrSimplifiedType), + ty::Array(..) | ty::Slice(_) => Some(ArraySimplifiedType), + ty::RawPtr(_) => Some(PtrSimplifiedType), + ty::Dynamic(ref trait_info, ..) => match trait_info.principal_def_id() { + Some(principal_def_id) if !tcx.trait_is_auto(principal_def_id) => { + Some(TraitSimplifiedType(principal_def_id)) + } + _ => Some(MarkerTraitObjectSimplifiedType), + }, + ty::Ref(_, ty, _) => { + // since we introduce auto-refs during method lookup, we + // just treat &T and T as equivalent from the point of + // view of possibly unifying + simplify_type(tcx, ty, can_simplify_params) + } + ty::FnDef(def_id, _) | ty::Closure(def_id, _) => Some(ClosureSimplifiedType(def_id)), + ty::Generator(def_id, _, _) => Some(GeneratorSimplifiedType(def_id)), + ty::GeneratorWitness(ref tys) => { + Some(GeneratorWitnessSimplifiedType(tys.skip_binder().len())) + } + ty::Never => Some(NeverSimplifiedType), + ty::Tuple(ref tys) => Some(TupleSimplifiedType(tys.len())), + ty::FnPtr(ref f) => Some(FunctionSimplifiedType(f.skip_binder().inputs().len())), + ty::Projection(_) | ty::Param(_) => { + if can_simplify_params { + // In normalized types, projections don't unify with + // anything. when lazy normalization happens, this + // will change. It would still be nice to have a way + // to deal with known-not-to-unify-with-anything + // projections (e.g., the likes of <__S as Encoder>::Error). + Some(ParameterSimplifiedType) + } else { + None + } + } + ty::Opaque(def_id, _) => Some(OpaqueSimplifiedType(def_id)), + ty::Foreign(def_id) => Some(ForeignSimplifiedType(def_id)), + ty::Placeholder(..) | ty::Bound(..) | ty::Infer(_) | ty::Error(_) => None, + } +} + +impl<D: Copy + Debug + Ord + Eq> SimplifiedTypeGen<D> { + pub fn map_def<U, F>(self, map: F) -> SimplifiedTypeGen<U> + where + F: Fn(D) -> U, + U: Copy + Debug + Ord + Eq, + { + match self { + BoolSimplifiedType => BoolSimplifiedType, + CharSimplifiedType => CharSimplifiedType, + IntSimplifiedType(t) => IntSimplifiedType(t), + UintSimplifiedType(t) => UintSimplifiedType(t), + FloatSimplifiedType(t) => FloatSimplifiedType(t), + AdtSimplifiedType(d) => AdtSimplifiedType(map(d)), + StrSimplifiedType => StrSimplifiedType, + ArraySimplifiedType => ArraySimplifiedType, + PtrSimplifiedType => PtrSimplifiedType, + NeverSimplifiedType => NeverSimplifiedType, + MarkerTraitObjectSimplifiedType => MarkerTraitObjectSimplifiedType, + TupleSimplifiedType(n) => TupleSimplifiedType(n), + TraitSimplifiedType(d) => TraitSimplifiedType(map(d)), + ClosureSimplifiedType(d) => ClosureSimplifiedType(map(d)), + GeneratorSimplifiedType(d) => GeneratorSimplifiedType(map(d)), + GeneratorWitnessSimplifiedType(n) => GeneratorWitnessSimplifiedType(n), + OpaqueSimplifiedType(d) => OpaqueSimplifiedType(map(d)), + FunctionSimplifiedType(n) => FunctionSimplifiedType(n), + ParameterSimplifiedType => ParameterSimplifiedType, + ForeignSimplifiedType(d) => ForeignSimplifiedType(d), + } + } +} + +impl<'a, D> HashStable<StableHashingContext<'a>> for SimplifiedTypeGen<D> +where + D: Copy + Debug + Ord + Eq + HashStable<StableHashingContext<'a>>, +{ + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + mem::discriminant(self).hash_stable(hcx, hasher); + match *self { + BoolSimplifiedType + | CharSimplifiedType + | StrSimplifiedType + | ArraySimplifiedType + | PtrSimplifiedType + | NeverSimplifiedType + | ParameterSimplifiedType + | MarkerTraitObjectSimplifiedType => { + // nothing to do + } + IntSimplifiedType(t) => t.hash_stable(hcx, hasher), + UintSimplifiedType(t) => t.hash_stable(hcx, hasher), + FloatSimplifiedType(t) => t.hash_stable(hcx, hasher), + AdtSimplifiedType(d) => d.hash_stable(hcx, hasher), + TupleSimplifiedType(n) => n.hash_stable(hcx, hasher), + TraitSimplifiedType(d) => d.hash_stable(hcx, hasher), + ClosureSimplifiedType(d) => d.hash_stable(hcx, hasher), + GeneratorSimplifiedType(d) => d.hash_stable(hcx, hasher), + GeneratorWitnessSimplifiedType(n) => n.hash_stable(hcx, hasher), + OpaqueSimplifiedType(d) => d.hash_stable(hcx, hasher), + FunctionSimplifiedType(n) => n.hash_stable(hcx, hasher), + ForeignSimplifiedType(d) => d.hash_stable(hcx, hasher), + } + } +} diff --git a/compiler/rustc_middle/src/ty/flags.rs b/compiler/rustc_middle/src/ty/flags.rs new file mode 100644 index 00000000000..27f50c240db --- /dev/null +++ b/compiler/rustc_middle/src/ty/flags.rs @@ -0,0 +1,330 @@ +use crate::ty::subst::{GenericArg, GenericArgKind}; +use crate::ty::{self, InferConst, Ty, TypeFlags}; +use std::slice; + +#[derive(Debug)] +pub struct FlagComputation { + pub flags: TypeFlags, + + // see `TyS::outer_exclusive_binder` for details + pub outer_exclusive_binder: ty::DebruijnIndex, +} + +impl FlagComputation { + fn new() -> FlagComputation { + FlagComputation { flags: TypeFlags::empty(), outer_exclusive_binder: ty::INNERMOST } + } + + #[allow(rustc::usage_of_ty_tykind)] + pub fn for_kind(kind: &ty::TyKind<'_>) -> FlagComputation { + let mut result = FlagComputation::new(); + result.add_kind(kind); + result + } + + pub fn for_predicate(kind: &ty::PredicateKind<'_>) -> FlagComputation { + let mut result = FlagComputation::new(); + result.add_predicate_kind(kind); + result + } + + pub fn for_const(c: &ty::Const<'_>) -> TypeFlags { + let mut result = FlagComputation::new(); + result.add_const(c); + result.flags + } + + fn add_flags(&mut self, flags: TypeFlags) { + self.flags = self.flags | flags; + } + + /// indicates that `self` refers to something at binding level `binder` + fn add_bound_var(&mut self, binder: ty::DebruijnIndex) { + let exclusive_binder = binder.shifted_in(1); + self.add_exclusive_binder(exclusive_binder); + } + + /// indicates that `self` refers to something *inside* binding + /// level `binder` -- not bound by `binder`, but bound by the next + /// binder internal to it + fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) { + self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder); + } + + /// Adds the flags/depth from a set of types that appear within the current type, but within a + /// region binder. + fn add_bound_computation(&mut self, computation: FlagComputation) { + self.add_flags(computation.flags); + + // The types that contributed to `computation` occurred within + // a region binder, so subtract one from the region depth + // within when adding the depth to `self`. + let outer_exclusive_binder = computation.outer_exclusive_binder; + if outer_exclusive_binder > ty::INNERMOST { + self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1)); + } // otherwise, this binder captures nothing + } + + #[allow(rustc::usage_of_ty_tykind)] + fn add_kind(&mut self, kind: &ty::TyKind<'_>) { + match kind { + &ty::Bool + | &ty::Char + | &ty::Int(_) + | &ty::Float(_) + | &ty::Uint(_) + | &ty::Never + | &ty::Str + | &ty::Foreign(..) => {} + + &ty::Error(_) => self.add_flags(TypeFlags::HAS_ERROR), + + &ty::Param(_) => { + self.add_flags(TypeFlags::HAS_TY_PARAM); + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + } + + &ty::Generator(_, ref substs, _) => { + let substs = substs.as_generator(); + let should_remove_further_specializable = + !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + self.add_substs(substs.parent_substs()); + if should_remove_further_specializable { + self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE; + } + + self.add_ty(substs.resume_ty()); + self.add_ty(substs.return_ty()); + self.add_ty(substs.witness()); + self.add_ty(substs.yield_ty()); + self.add_ty(substs.tupled_upvars_ty()); + } + + &ty::GeneratorWitness(ts) => { + let mut computation = FlagComputation::new(); + computation.add_tys(ts.skip_binder()); + self.add_bound_computation(computation); + } + + &ty::Closure(_, substs) => { + let substs = substs.as_closure(); + let should_remove_further_specializable = + !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + self.add_substs(substs.parent_substs()); + if should_remove_further_specializable { + self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE; + } + + self.add_ty(substs.sig_as_fn_ptr_ty()); + self.add_ty(substs.kind_ty()); + self.add_ty(substs.tupled_upvars_ty()); + } + + &ty::Bound(debruijn, _) => { + self.add_bound_var(debruijn); + } + + &ty::Placeholder(..) => { + self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER); + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + } + + &ty::Infer(infer) => { + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + match infer { + ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {} + + ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => { + self.add_flags(TypeFlags::HAS_TY_INFER) + } + } + } + + &ty::Adt(_, substs) => { + self.add_substs(substs); + } + + &ty::Projection(data) => { + self.add_flags(TypeFlags::HAS_TY_PROJECTION); + self.add_projection_ty(data); + } + + &ty::Opaque(_, substs) => { + self.add_flags(TypeFlags::HAS_TY_OPAQUE); + self.add_substs(substs); + } + + &ty::Dynamic(ref obj, r) => { + let mut computation = FlagComputation::new(); + for predicate in obj.skip_binder().iter() { + match predicate { + ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs), + ty::ExistentialPredicate::Projection(p) => { + let mut proj_computation = FlagComputation::new(); + proj_computation.add_existential_projection(&p); + self.add_bound_computation(proj_computation); + } + ty::ExistentialPredicate::AutoTrait(_) => {} + } + } + self.add_bound_computation(computation); + self.add_region(r); + } + + &ty::Array(tt, len) => { + self.add_ty(tt); + self.add_const(len); + } + + &ty::Slice(tt) => self.add_ty(tt), + + &ty::RawPtr(ref m) => { + self.add_ty(m.ty); + } + + &ty::Ref(r, ty, _) => { + self.add_region(r); + self.add_ty(ty); + } + + &ty::Tuple(ref substs) => { + self.add_substs(substs); + } + + &ty::FnDef(_, substs) => { + self.add_substs(substs); + } + + &ty::FnPtr(f) => { + self.add_fn_sig(f); + } + } + } + + fn add_predicate_kind(&mut self, kind: &ty::PredicateKind<'_>) { + match kind { + ty::PredicateKind::ForAll(binder) => { + let mut computation = FlagComputation::new(); + + computation.add_predicate_atom(binder.skip_binder()); + + self.add_bound_computation(computation); + } + &ty::PredicateKind::Atom(atom) => self.add_predicate_atom(atom), + } + } + + fn add_predicate_atom(&mut self, atom: ty::PredicateAtom<'_>) { + match atom { + ty::PredicateAtom::Trait(trait_pred, _constness) => { + self.add_substs(trait_pred.trait_ref.substs); + } + ty::PredicateAtom::RegionOutlives(ty::OutlivesPredicate(a, b)) => { + self.add_region(a); + self.add_region(b); + } + ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(ty, region)) => { + self.add_ty(ty); + self.add_region(region); + } + ty::PredicateAtom::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => { + self.add_ty(a); + self.add_ty(b); + } + ty::PredicateAtom::Projection(ty::ProjectionPredicate { projection_ty, ty }) => { + self.add_projection_ty(projection_ty); + self.add_ty(ty); + } + ty::PredicateAtom::WellFormed(arg) => { + self.add_substs(slice::from_ref(&arg)); + } + ty::PredicateAtom::ObjectSafe(_def_id) => {} + ty::PredicateAtom::ClosureKind(_def_id, substs, _kind) => { + self.add_substs(substs); + } + ty::PredicateAtom::ConstEvaluatable(_def_id, substs) => { + self.add_substs(substs); + } + ty::PredicateAtom::ConstEquate(expected, found) => { + self.add_const(expected); + self.add_const(found); + } + } + } + + fn add_ty(&mut self, ty: Ty<'_>) { + self.add_flags(ty.flags); + self.add_exclusive_binder(ty.outer_exclusive_binder); + } + + fn add_tys(&mut self, tys: &[Ty<'_>]) { + for &ty in tys { + self.add_ty(ty); + } + } + + fn add_fn_sig(&mut self, fn_sig: ty::PolyFnSig<'_>) { + let mut computation = FlagComputation::new(); + + computation.add_tys(fn_sig.skip_binder().inputs()); + computation.add_ty(fn_sig.skip_binder().output()); + + self.add_bound_computation(computation); + } + + fn add_region(&mut self, r: ty::Region<'_>) { + self.add_flags(r.type_flags()); + if let ty::ReLateBound(debruijn, _) = *r { + self.add_bound_var(debruijn); + } + } + + fn add_const(&mut self, c: &ty::Const<'_>) { + self.add_ty(c.ty); + match c.val { + ty::ConstKind::Unevaluated(_, substs, _) => { + self.add_substs(substs); + self.add_flags(TypeFlags::HAS_CT_PROJECTION); + } + ty::ConstKind::Infer(infer) => { + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + match infer { + InferConst::Fresh(_) => {} + InferConst::Var(_) => self.add_flags(TypeFlags::HAS_CT_INFER), + } + } + ty::ConstKind::Bound(debruijn, _) => { + self.add_bound_var(debruijn); + } + ty::ConstKind::Param(_) => { + self.add_flags(TypeFlags::HAS_CT_PARAM); + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + } + ty::ConstKind::Placeholder(_) => { + self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER); + self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE); + } + ty::ConstKind::Value(_) => {} + ty::ConstKind::Error(_) => self.add_flags(TypeFlags::HAS_ERROR), + } + } + + fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) { + self.add_substs(projection.substs); + self.add_ty(projection.ty); + } + + fn add_projection_ty(&mut self, projection_ty: ty::ProjectionTy<'_>) { + self.add_substs(projection_ty.substs); + } + + fn add_substs(&mut self, substs: &[GenericArg<'_>]) { + for kind in substs { + match kind.unpack() { + GenericArgKind::Type(ty) => self.add_ty(ty), + GenericArgKind::Lifetime(lt) => self.add_region(lt), + GenericArgKind::Const(ct) => self.add_const(ct), + } + } + } +} diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs new file mode 100644 index 00000000000..492f8ce9ef1 --- /dev/null +++ b/compiler/rustc_middle/src/ty/fold.rs @@ -0,0 +1,1019 @@ +//! Generalized type folding mechanism. The setup is a bit convoluted +//! but allows for convenient usage. Let T be an instance of some +//! "foldable type" (one which implements `TypeFoldable`) and F be an +//! instance of a "folder" (a type which implements `TypeFolder`). Then +//! the setup is intended to be: +//! +//! T.fold_with(F) --calls--> F.fold_T(T) --calls--> T.super_fold_with(F) +//! +//! This way, when you define a new folder F, you can override +//! `fold_T()` to customize the behavior, and invoke `T.super_fold_with()` +//! to get the original behavior. Meanwhile, to actually fold +//! something, you can just write `T.fold_with(F)`, which is +//! convenient. (Note that `fold_with` will also transparently handle +//! things like a `Vec<T>` where T is foldable and so on.) +//! +//! In this ideal setup, the only function that actually *does* +//! anything is `T.super_fold_with()`, which traverses the type `T`. +//! Moreover, `T.super_fold_with()` should only ever call `T.fold_with()`. +//! +//! In some cases, we follow a degenerate pattern where we do not have +//! a `fold_T` method. Instead, `T.fold_with` traverses the structure directly. +//! This is suboptimal because the behavior cannot be overridden, but it's +//! much less work to implement. If you ever *do* need an override that +//! doesn't exist, it's not hard to convert the degenerate pattern into the +//! proper thing. +//! +//! A `TypeFoldable` T can also be visited by a `TypeVisitor` V using similar setup: +//! +//! T.visit_with(V) --calls--> V.visit_T(T) --calls--> T.super_visit_with(V). +//! +//! These methods return true to indicate that the visitor has found what it is +//! looking for, and does not need to visit anything else. + +use crate::ty::structural_impls::PredicateVisitor; +use crate::ty::{self, flags::FlagComputation, Binder, Ty, TyCtxt, TypeFlags}; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; + +use rustc_data_structures::fx::FxHashSet; +use std::collections::BTreeMap; +use std::fmt; + +/// This trait is implemented for every type that can be folded. +/// Basically, every type that has a corresponding method in `TypeFolder`. +/// +/// To implement this conveniently, use the derive macro located in librustc_macros. +pub trait TypeFoldable<'tcx>: fmt::Debug + Clone { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self; + fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + self.super_fold_with(folder) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool; + fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.super_visit_with(visitor) + } + + /// Returns `true` if `self` has any late-bound regions that are either + /// bound by `binder` or bound by some binder outside of `binder`. + /// If `binder` is `ty::INNERMOST`, this indicates whether + /// there are any late-bound regions that appear free. + fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool { + self.visit_with(&mut HasEscapingVarsVisitor { outer_index: binder }) + } + + /// Returns `true` if this `self` has any regions that escape `binder` (and + /// hence are not bound by it). + fn has_vars_bound_above(&self, binder: ty::DebruijnIndex) -> bool { + self.has_vars_bound_at_or_above(binder.shifted_in(1)) + } + + fn has_escaping_bound_vars(&self) -> bool { + self.has_vars_bound_at_or_above(ty::INNERMOST) + } + + fn has_type_flags(&self, flags: TypeFlags) -> bool { + self.visit_with(&mut HasTypeFlagsVisitor { flags }) + } + fn has_projections(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_PROJECTION) + } + fn has_opaque_types(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_TY_OPAQUE) + } + fn references_error(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_ERROR) + } + fn has_param_types_or_consts(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_TY_PARAM | TypeFlags::HAS_CT_PARAM) + } + fn has_infer_regions(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_RE_INFER) + } + fn has_infer_types(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_TY_INFER) + } + fn has_infer_types_or_consts(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_TY_INFER | TypeFlags::HAS_CT_INFER) + } + fn has_infer_consts(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_CT_INFER) + } + fn needs_infer(&self) -> bool { + self.has_type_flags(TypeFlags::NEEDS_INFER) + } + fn has_placeholders(&self) -> bool { + self.has_type_flags( + TypeFlags::HAS_RE_PLACEHOLDER + | TypeFlags::HAS_TY_PLACEHOLDER + | TypeFlags::HAS_CT_PLACEHOLDER, + ) + } + fn needs_subst(&self) -> bool { + self.has_type_flags(TypeFlags::NEEDS_SUBST) + } + fn has_re_placeholders(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_RE_PLACEHOLDER) + } + /// "Free" regions in this context means that it has any region + /// that is not (a) erased or (b) late-bound. + fn has_free_regions(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_FREE_REGIONS) + } + + fn has_erased_regions(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_RE_ERASED) + } + + /// True if there are any un-erased free regions. + fn has_erasable_regions(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_FREE_REGIONS) + } + + /// Indicates whether this value references only 'global' + /// generic parameters that are the same regardless of what fn we are + /// in. This is used for caching. + fn is_global(&self) -> bool { + !self.has_type_flags(TypeFlags::HAS_FREE_LOCAL_NAMES) + } + + /// True if there are any late-bound regions + fn has_late_bound_regions(&self) -> bool { + self.has_type_flags(TypeFlags::HAS_RE_LATE_BOUND) + } + + /// Indicates whether this value still has parameters/placeholders/inference variables + /// which could be replaced later, in a way that would change the results of `impl` + /// specialization. + fn still_further_specializable(&self) -> bool { + self.has_type_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE) + } + + /// A visitor that does not recurse into types, works like `fn walk_shallow` in `Ty`. + fn visit_tys_shallow(&self, visit: impl FnMut(Ty<'tcx>) -> bool) -> bool { + pub struct Visitor<F>(F); + + impl<'tcx, F: FnMut(Ty<'tcx>) -> bool> TypeVisitor<'tcx> for Visitor<F> { + fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool { + self.0(ty) + } + } + + self.visit_with(&mut Visitor(visit)) + } +} + +impl TypeFoldable<'tcx> for hir::Constness { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, _: &mut F) -> Self { + *self + } + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool { + false + } +} + +/// The `TypeFolder` trait defines the actual *folding*. There is a +/// method defined for every foldable type. Each of these has a +/// default implementation that does an "identity" fold. Within each +/// identity fold, it should invoke `foo.fold_with(self)` to fold each +/// sub-item. +pub trait TypeFolder<'tcx>: Sized { + fn tcx<'a>(&'a self) -> TyCtxt<'tcx>; + + fn fold_binder<T>(&mut self, t: &Binder<T>) -> Binder<T> + where + T: TypeFoldable<'tcx>, + { + t.super_fold_with(self) + } + + fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { + t.super_fold_with(self) + } + + fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { + r.super_fold_with(self) + } + + fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { + c.super_fold_with(self) + } +} + +pub trait TypeVisitor<'tcx>: Sized { + fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> bool { + t.super_visit_with(self) + } + + fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { + t.super_visit_with(self) + } + + fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool { + r.super_visit_with(self) + } + + fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool { + c.super_visit_with(self) + } +} + +/////////////////////////////////////////////////////////////////////////// +// Some sample folders + +pub struct BottomUpFolder<'tcx, F, G, H> +where + F: FnMut(Ty<'tcx>) -> Ty<'tcx>, + G: FnMut(ty::Region<'tcx>) -> ty::Region<'tcx>, + H: FnMut(&'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx>, +{ + pub tcx: TyCtxt<'tcx>, + pub ty_op: F, + pub lt_op: G, + pub ct_op: H, +} + +impl<'tcx, F, G, H> TypeFolder<'tcx> for BottomUpFolder<'tcx, F, G, H> +where + F: FnMut(Ty<'tcx>) -> Ty<'tcx>, + G: FnMut(ty::Region<'tcx>) -> ty::Region<'tcx>, + H: FnMut(&'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx>, +{ + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { + let t = ty.super_fold_with(self); + (self.ty_op)(t) + } + + fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { + let r = r.super_fold_with(self); + (self.lt_op)(r) + } + + fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { + let ct = ct.super_fold_with(self); + (self.ct_op)(ct) + } +} + +/////////////////////////////////////////////////////////////////////////// +// Region folder + +impl<'tcx> TyCtxt<'tcx> { + /// Folds the escaping and free regions in `value` using `f`, and + /// sets `skipped_regions` to true if any late-bound region was found + /// and skipped. + pub fn fold_regions<T>( + self, + value: &T, + skipped_regions: &mut bool, + mut f: impl FnMut(ty::Region<'tcx>, ty::DebruijnIndex) -> ty::Region<'tcx>, + ) -> T + where + T: TypeFoldable<'tcx>, + { + value.fold_with(&mut RegionFolder::new(self, skipped_regions, &mut f)) + } + + /// Invoke `callback` on every region appearing free in `value`. + pub fn for_each_free_region( + self, + value: &impl TypeFoldable<'tcx>, + mut callback: impl FnMut(ty::Region<'tcx>), + ) { + self.any_free_region_meets(value, |r| { + callback(r); + false + }); + } + + /// Returns `true` if `callback` returns true for every region appearing free in `value`. + pub fn all_free_regions_meet( + self, + value: &impl TypeFoldable<'tcx>, + mut callback: impl FnMut(ty::Region<'tcx>) -> bool, + ) -> bool { + !self.any_free_region_meets(value, |r| !callback(r)) + } + + /// Returns `true` if `callback` returns true for some region appearing free in `value`. + pub fn any_free_region_meets( + self, + value: &impl TypeFoldable<'tcx>, + callback: impl FnMut(ty::Region<'tcx>) -> bool, + ) -> bool { + return value.visit_with(&mut RegionVisitor { outer_index: ty::INNERMOST, callback }); + + struct RegionVisitor<F> { + /// The index of a binder *just outside* the things we have + /// traversed. If we encounter a bound region bound by this + /// binder or one outer to it, it appears free. Example: + /// + /// ``` + /// for<'a> fn(for<'b> fn(), T) + /// ^ ^ ^ ^ + /// | | | | here, would be shifted in 1 + /// | | | here, would be shifted in 2 + /// | | here, would be `INNERMOST` shifted in by 1 + /// | here, initially, binder would be `INNERMOST` + /// ``` + /// + /// You see that, initially, *any* bound value is free, + /// because we've not traversed any binders. As we pass + /// through a binder, we shift the `outer_index` by 1 to + /// account for the new binder that encloses us. + outer_index: ty::DebruijnIndex, + callback: F, + } + + impl<'tcx, F> TypeVisitor<'tcx> for RegionVisitor<F> + where + F: FnMut(ty::Region<'tcx>) -> bool, + { + fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> bool { + self.outer_index.shift_in(1); + let result = t.as_ref().skip_binder().visit_with(self); + self.outer_index.shift_out(1); + result + } + + fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool { + match *r { + ty::ReLateBound(debruijn, _) if debruijn < self.outer_index => { + false // ignore bound regions, keep visiting + } + _ => (self.callback)(r), + } + } + + fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool { + // We're only interested in types involving regions + if ty.flags.intersects(TypeFlags::HAS_FREE_REGIONS) { + ty.super_visit_with(self) + } else { + false // keep visiting + } + } + } + } +} + +/// Folds over the substructure of a type, visiting its component +/// types and all regions that occur *free* within it. +/// +/// That is, `Ty` can contain function or method types that bind +/// regions at the call site (`ReLateBound`), and occurrences of +/// regions (aka "lifetimes") that are bound within a type are not +/// visited by this folder; only regions that occur free will be +/// visited by `fld_r`. + +pub struct RegionFolder<'a, 'tcx> { + tcx: TyCtxt<'tcx>, + skipped_regions: &'a mut bool, + + /// Stores the index of a binder *just outside* the stuff we have + /// visited. So this begins as INNERMOST; when we pass through a + /// binder, it is incremented (via `shift_in`). + current_index: ty::DebruijnIndex, + + /// Callback invokes for each free region. The `DebruijnIndex` + /// points to the binder *just outside* the ones we have passed + /// through. + fold_region_fn: + &'a mut (dyn FnMut(ty::Region<'tcx>, ty::DebruijnIndex) -> ty::Region<'tcx> + 'a), +} + +impl<'a, 'tcx> RegionFolder<'a, 'tcx> { + #[inline] + pub fn new( + tcx: TyCtxt<'tcx>, + skipped_regions: &'a mut bool, + fold_region_fn: &'a mut dyn FnMut(ty::Region<'tcx>, ty::DebruijnIndex) -> ty::Region<'tcx>, + ) -> RegionFolder<'a, 'tcx> { + RegionFolder { tcx, skipped_regions, current_index: ty::INNERMOST, fold_region_fn } + } +} + +impl<'a, 'tcx> TypeFolder<'tcx> for RegionFolder<'a, 'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &ty::Binder<T>) -> ty::Binder<T> { + self.current_index.shift_in(1); + let t = t.super_fold_with(self); + self.current_index.shift_out(1); + t + } + + fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { + match *r { + ty::ReLateBound(debruijn, _) if debruijn < self.current_index => { + debug!( + "RegionFolder.fold_region({:?}) skipped bound region (current index={:?})", + r, self.current_index + ); + *self.skipped_regions = true; + r + } + _ => { + debug!( + "RegionFolder.fold_region({:?}) folding free region (current_index={:?})", + r, self.current_index + ); + (self.fold_region_fn)(r, self.current_index) + } + } + } +} + +/////////////////////////////////////////////////////////////////////////// +// Bound vars replacer + +/// Replaces the escaping bound vars (late bound regions or bound types) in a type. +struct BoundVarReplacer<'a, 'tcx> { + tcx: TyCtxt<'tcx>, + + /// As with `RegionFolder`, represents the index of a binder *just outside* + /// the ones we have visited. + current_index: ty::DebruijnIndex, + + fld_r: &'a mut (dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx> + 'a), + fld_t: &'a mut (dyn FnMut(ty::BoundTy) -> Ty<'tcx> + 'a), + fld_c: &'a mut (dyn FnMut(ty::BoundVar, Ty<'tcx>) -> &'tcx ty::Const<'tcx> + 'a), +} + +impl<'a, 'tcx> BoundVarReplacer<'a, 'tcx> { + fn new<F, G, H>(tcx: TyCtxt<'tcx>, fld_r: &'a mut F, fld_t: &'a mut G, fld_c: &'a mut H) -> Self + where + F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>, + G: FnMut(ty::BoundTy) -> Ty<'tcx>, + H: FnMut(ty::BoundVar, Ty<'tcx>) -> &'tcx ty::Const<'tcx>, + { + BoundVarReplacer { tcx, current_index: ty::INNERMOST, fld_r, fld_t, fld_c } + } +} + +impl<'a, 'tcx> TypeFolder<'tcx> for BoundVarReplacer<'a, 'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &ty::Binder<T>) -> ty::Binder<T> { + self.current_index.shift_in(1); + let t = t.super_fold_with(self); + self.current_index.shift_out(1); + t + } + + fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { + match t.kind { + ty::Bound(debruijn, bound_ty) => { + if debruijn == self.current_index { + let fld_t = &mut self.fld_t; + let ty = fld_t(bound_ty); + ty::fold::shift_vars(self.tcx, &ty, self.current_index.as_u32()) + } else { + t + } + } + _ => { + if !t.has_vars_bound_at_or_above(self.current_index) { + // Nothing more to substitute. + t + } else { + t.super_fold_with(self) + } + } + } + } + + fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { + match *r { + ty::ReLateBound(debruijn, br) if debruijn == self.current_index => { + let fld_r = &mut self.fld_r; + let region = fld_r(br); + if let ty::ReLateBound(debruijn1, br) = *region { + // If the callback returns a late-bound region, + // that region should always use the INNERMOST + // debruijn index. Then we adjust it to the + // correct depth. + assert_eq!(debruijn1, ty::INNERMOST); + self.tcx.mk_region(ty::ReLateBound(debruijn, br)) + } else { + region + } + } + _ => r, + } + } + + fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { + if let ty::Const { val: ty::ConstKind::Bound(debruijn, bound_const), ty } = *ct { + if debruijn == self.current_index { + let fld_c = &mut self.fld_c; + let ct = fld_c(bound_const, ty); + ty::fold::shift_vars(self.tcx, &ct, self.current_index.as_u32()) + } else { + ct + } + } else { + if !ct.has_vars_bound_at_or_above(self.current_index) { + // Nothing more to substitute. + ct + } else { + ct.super_fold_with(self) + } + } + } +} + +impl<'tcx> TyCtxt<'tcx> { + /// Replaces all regions bound by the given `Binder` with the + /// results returned by the closure; the closure is expected to + /// return a free region (relative to this binder), and hence the + /// binder is removed in the return type. The closure is invoked + /// once for each unique `BoundRegion`; multiple references to the + /// same `BoundRegion` will reuse the previous result. A map is + /// returned at the end with each bound region and the free region + /// that replaced it. + /// + /// This method only replaces late bound regions and the result may still + /// contain escaping bound types. + pub fn replace_late_bound_regions<T, F>( + self, + value: &Binder<T>, + fld_r: F, + ) -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>) + where + F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>, + T: TypeFoldable<'tcx>, + { + // identity for bound types and consts + let fld_t = |bound_ty| self.mk_ty(ty::Bound(ty::INNERMOST, bound_ty)); + let fld_c = |bound_ct, ty| { + self.mk_const(ty::Const { val: ty::ConstKind::Bound(ty::INNERMOST, bound_ct), ty }) + }; + self.replace_escaping_bound_vars(value.as_ref().skip_binder(), fld_r, fld_t, fld_c) + } + + /// Replaces all escaping bound vars. The `fld_r` closure replaces escaping + /// bound regions; the `fld_t` closure replaces escaping bound types and the `fld_c` + /// closure replaces escaping bound consts. + pub fn replace_escaping_bound_vars<T, F, G, H>( + self, + value: &T, + mut fld_r: F, + mut fld_t: G, + mut fld_c: H, + ) -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>) + where + F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>, + G: FnMut(ty::BoundTy) -> Ty<'tcx>, + H: FnMut(ty::BoundVar, Ty<'tcx>) -> &'tcx ty::Const<'tcx>, + T: TypeFoldable<'tcx>, + { + use rustc_data_structures::fx::FxHashMap; + + let mut region_map = BTreeMap::new(); + let mut type_map = FxHashMap::default(); + let mut const_map = FxHashMap::default(); + + if !value.has_escaping_bound_vars() { + (value.clone(), region_map) + } else { + let mut real_fld_r = |br| *region_map.entry(br).or_insert_with(|| fld_r(br)); + + let mut real_fld_t = + |bound_ty| *type_map.entry(bound_ty).or_insert_with(|| fld_t(bound_ty)); + + let mut real_fld_c = + |bound_ct, ty| *const_map.entry(bound_ct).or_insert_with(|| fld_c(bound_ct, ty)); + + let mut replacer = + BoundVarReplacer::new(self, &mut real_fld_r, &mut real_fld_t, &mut real_fld_c); + let result = value.fold_with(&mut replacer); + (result, region_map) + } + } + + /// Replaces all types or regions bound by the given `Binder`. The `fld_r` + /// closure replaces bound regions while the `fld_t` closure replaces bound + /// types. + pub fn replace_bound_vars<T, F, G, H>( + self, + value: &Binder<T>, + fld_r: F, + fld_t: G, + fld_c: H, + ) -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>) + where + F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>, + G: FnMut(ty::BoundTy) -> Ty<'tcx>, + H: FnMut(ty::BoundVar, Ty<'tcx>) -> &'tcx ty::Const<'tcx>, + T: TypeFoldable<'tcx>, + { + self.replace_escaping_bound_vars(value.as_ref().skip_binder(), fld_r, fld_t, fld_c) + } + + /// Replaces any late-bound regions bound in `value` with + /// free variants attached to `all_outlive_scope`. + pub fn liberate_late_bound_regions<T>( + &self, + all_outlive_scope: DefId, + value: &ty::Binder<T>, + ) -> T + where + T: TypeFoldable<'tcx>, + { + self.replace_late_bound_regions(value, |br| { + self.mk_region(ty::ReFree(ty::FreeRegion { + scope: all_outlive_scope, + bound_region: br, + })) + }) + .0 + } + + /// Returns a set of all late-bound regions that are constrained + /// by `value`, meaning that if we instantiate those LBR with + /// variables and equate `value` with something else, those + /// variables will also be equated. + pub fn collect_constrained_late_bound_regions<T>( + &self, + value: &Binder<T>, + ) -> FxHashSet<ty::BoundRegion> + where + T: TypeFoldable<'tcx>, + { + self.collect_late_bound_regions(value, true) + } + + /// Returns a set of all late-bound regions that appear in `value` anywhere. + pub fn collect_referenced_late_bound_regions<T>( + &self, + value: &Binder<T>, + ) -> FxHashSet<ty::BoundRegion> + where + T: TypeFoldable<'tcx>, + { + self.collect_late_bound_regions(value, false) + } + + fn collect_late_bound_regions<T>( + &self, + value: &Binder<T>, + just_constraint: bool, + ) -> FxHashSet<ty::BoundRegion> + where + T: TypeFoldable<'tcx>, + { + let mut collector = LateBoundRegionsCollector::new(just_constraint); + let result = value.as_ref().skip_binder().visit_with(&mut collector); + assert!(!result); // should never have stopped early + collector.regions + } + + /// Replaces any late-bound regions bound in `value` with `'erased`. Useful in codegen but also + /// method lookup and a few other places where precise region relationships are not required. + pub fn erase_late_bound_regions<T>(self, value: &Binder<T>) -> T + where + T: TypeFoldable<'tcx>, + { + self.replace_late_bound_regions(value, |_| self.lifetimes.re_erased).0 + } + + /// Rewrite any late-bound regions so that they are anonymous. Region numbers are + /// assigned starting at 1 and increasing monotonically in the order traversed + /// by the fold operation. + /// + /// The chief purpose of this function is to canonicalize regions so that two + /// `FnSig`s or `TraitRef`s which are equivalent up to region naming will become + /// structurally identical. For example, `for<'a, 'b> fn(&'a isize, &'b isize)` and + /// `for<'a, 'b> fn(&'b isize, &'a isize)` will become identical after anonymization. + pub fn anonymize_late_bound_regions<T>(self, sig: &Binder<T>) -> Binder<T> + where + T: TypeFoldable<'tcx>, + { + let mut counter = 0; + Binder::bind( + self.replace_late_bound_regions(sig, |_| { + counter += 1; + self.mk_region(ty::ReLateBound(ty::INNERMOST, ty::BrAnon(counter))) + }) + .0, + ) + } +} + +/////////////////////////////////////////////////////////////////////////// +// Shifter +// +// Shifts the De Bruijn indices on all escaping bound vars by a +// fixed amount. Useful in substitution or when otherwise introducing +// a binding level that is not intended to capture the existing bound +// vars. See comment on `shift_vars_through_binders` method in +// `subst.rs` for more details. + +enum Direction { + In, + Out, +} + +struct Shifter<'tcx> { + tcx: TyCtxt<'tcx>, + current_index: ty::DebruijnIndex, + amount: u32, + direction: Direction, +} + +impl Shifter<'tcx> { + pub fn new(tcx: TyCtxt<'tcx>, amount: u32, direction: Direction) -> Self { + Shifter { tcx, current_index: ty::INNERMOST, amount, direction } + } +} + +impl TypeFolder<'tcx> for Shifter<'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &ty::Binder<T>) -> ty::Binder<T> { + self.current_index.shift_in(1); + let t = t.super_fold_with(self); + self.current_index.shift_out(1); + t + } + + fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { + match *r { + ty::ReLateBound(debruijn, br) => { + if self.amount == 0 || debruijn < self.current_index { + r + } else { + let debruijn = match self.direction { + Direction::In => debruijn.shifted_in(self.amount), + Direction::Out => { + assert!(debruijn.as_u32() >= self.amount); + debruijn.shifted_out(self.amount) + } + }; + let shifted = ty::ReLateBound(debruijn, br); + self.tcx.mk_region(shifted) + } + } + _ => r, + } + } + + fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { + match ty.kind { + ty::Bound(debruijn, bound_ty) => { + if self.amount == 0 || debruijn < self.current_index { + ty + } else { + let debruijn = match self.direction { + Direction::In => debruijn.shifted_in(self.amount), + Direction::Out => { + assert!(debruijn.as_u32() >= self.amount); + debruijn.shifted_out(self.amount) + } + }; + self.tcx.mk_ty(ty::Bound(debruijn, bound_ty)) + } + } + + _ => ty.super_fold_with(self), + } + } + + fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { + if let ty::Const { val: ty::ConstKind::Bound(debruijn, bound_ct), ty } = *ct { + if self.amount == 0 || debruijn < self.current_index { + ct + } else { + let debruijn = match self.direction { + Direction::In => debruijn.shifted_in(self.amount), + Direction::Out => { + assert!(debruijn.as_u32() >= self.amount); + debruijn.shifted_out(self.amount) + } + }; + self.tcx.mk_const(ty::Const { val: ty::ConstKind::Bound(debruijn, bound_ct), ty }) + } + } else { + ct.super_fold_with(self) + } + } +} + +pub fn shift_region<'tcx>( + tcx: TyCtxt<'tcx>, + region: ty::Region<'tcx>, + amount: u32, +) -> ty::Region<'tcx> { + match region { + ty::ReLateBound(debruijn, br) if amount > 0 => { + tcx.mk_region(ty::ReLateBound(debruijn.shifted_in(amount), *br)) + } + _ => region, + } +} + +pub fn shift_vars<'tcx, T>(tcx: TyCtxt<'tcx>, value: &T, amount: u32) -> T +where + T: TypeFoldable<'tcx>, +{ + debug!("shift_vars(value={:?}, amount={})", value, amount); + + value.fold_with(&mut Shifter::new(tcx, amount, Direction::In)) +} + +pub fn shift_out_vars<'tcx, T>(tcx: TyCtxt<'tcx>, value: &T, amount: u32) -> T +where + T: TypeFoldable<'tcx>, +{ + debug!("shift_out_vars(value={:?}, amount={})", value, amount); + + value.fold_with(&mut Shifter::new(tcx, amount, Direction::Out)) +} + +/// An "escaping var" is a bound var whose binder is not part of `t`. A bound var can be a +/// bound region or a bound type. +/// +/// So, for example, consider a type like the following, which has two binders: +/// +/// for<'a> fn(x: for<'b> fn(&'a isize, &'b isize)) +/// ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ outer scope +/// ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ inner scope +/// +/// This type has *bound regions* (`'a`, `'b`), but it does not have escaping regions, because the +/// binders of both `'a` and `'b` are part of the type itself. However, if we consider the *inner +/// fn type*, that type has an escaping region: `'a`. +/// +/// Note that what I'm calling an "escaping var" is often just called a "free var". However, +/// we already use the term "free var". It refers to the regions or types that we use to represent +/// bound regions or type params on a fn definition while we are type checking its body. +/// +/// To clarify, conceptually there is no particular difference between +/// an "escaping" var and a "free" var. However, there is a big +/// difference in practice. Basically, when "entering" a binding +/// level, one is generally required to do some sort of processing to +/// a bound var, such as replacing it with a fresh/placeholder +/// var, or making an entry in the environment to represent the +/// scope to which it is attached, etc. An escaping var represents +/// a bound var for which this processing has not yet been done. +struct HasEscapingVarsVisitor { + /// Anything bound by `outer_index` or "above" is escaping. + outer_index: ty::DebruijnIndex, +} + +impl<'tcx> TypeVisitor<'tcx> for HasEscapingVarsVisitor { + fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> bool { + self.outer_index.shift_in(1); + let result = t.super_visit_with(self); + self.outer_index.shift_out(1); + result + } + + fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { + // If the outer-exclusive-binder is *strictly greater* than + // `outer_index`, that means that `t` contains some content + // bound at `outer_index` or above (because + // `outer_exclusive_binder` is always 1 higher than the + // content in `t`). Therefore, `t` has some escaping vars. + t.outer_exclusive_binder > self.outer_index + } + + fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool { + // If the region is bound by `outer_index` or anything outside + // of outer index, then it escapes the binders we have + // visited. + r.bound_at_or_above_binder(self.outer_index) + } + + fn visit_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> bool { + // we don't have a `visit_infer_const` callback, so we have to + // hook in here to catch this case (annoying...), but + // otherwise we do want to remember to visit the rest of the + // const, as it has types/regions embedded in a lot of other + // places. + match ct.val { + ty::ConstKind::Bound(debruijn, _) if debruijn >= self.outer_index => true, + _ => ct.super_visit_with(self), + } + } +} + +impl<'tcx> PredicateVisitor<'tcx> for HasEscapingVarsVisitor { + fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> bool { + predicate.inner.outer_exclusive_binder > self.outer_index + } +} + +// FIXME: Optimize for checking for infer flags +struct HasTypeFlagsVisitor { + flags: ty::TypeFlags, +} + +impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor { + fn visit_ty(&mut self, t: Ty<'_>) -> bool { + debug!("HasTypeFlagsVisitor: t={:?} t.flags={:?} self.flags={:?}", t, t.flags, self.flags); + t.flags.intersects(self.flags) + } + + fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool { + let flags = r.type_flags(); + debug!("HasTypeFlagsVisitor: r={:?} r.flags={:?} self.flags={:?}", r, flags, self.flags); + flags.intersects(self.flags) + } + + fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool { + let flags = FlagComputation::for_const(c); + debug!("HasTypeFlagsVisitor: c={:?} c.flags={:?} self.flags={:?}", c, flags, self.flags); + flags.intersects(self.flags) + } +} + +impl<'tcx> PredicateVisitor<'tcx> for HasTypeFlagsVisitor { + fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> bool { + debug!( + "HasTypeFlagsVisitor: predicate={:?} predicate.flags={:?} self.flags={:?}", + predicate, predicate.inner.flags, self.flags + ); + predicate.inner.flags.intersects(self.flags) + } +} +/// Collects all the late-bound regions at the innermost binding level +/// into a hash set. +struct LateBoundRegionsCollector { + current_index: ty::DebruijnIndex, + regions: FxHashSet<ty::BoundRegion>, + + /// `true` if we only want regions that are known to be + /// "constrained" when you equate this type with another type. In + /// particular, if you have e.g., `&'a u32` and `&'b u32`, equating + /// them constraints `'a == 'b`. But if you have `<&'a u32 as + /// Trait>::Foo` and `<&'b u32 as Trait>::Foo`, normalizing those + /// types may mean that `'a` and `'b` don't appear in the results, + /// so they are not considered *constrained*. + just_constrained: bool, +} + +impl LateBoundRegionsCollector { + fn new(just_constrained: bool) -> Self { + LateBoundRegionsCollector { + current_index: ty::INNERMOST, + regions: Default::default(), + just_constrained, + } + } +} + +impl<'tcx> TypeVisitor<'tcx> for LateBoundRegionsCollector { + fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> bool { + self.current_index.shift_in(1); + let result = t.super_visit_with(self); + self.current_index.shift_out(1); + result + } + + fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { + // if we are only looking for "constrained" region, we have to + // ignore the inputs to a projection, as they may not appear + // in the normalized form + if self.just_constrained { + if let ty::Projection(..) | ty::Opaque(..) = t.kind { + return false; + } + } + + t.super_visit_with(self) + } + + fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool { + // if we are only looking for "constrained" region, we have to + // ignore the inputs of an unevaluated const, as they may not appear + // in the normalized form + if self.just_constrained { + if let ty::ConstKind::Unevaluated(..) = c.val { + return false; + } + } + + c.super_visit_with(self) + } + + fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool { + if let ty::ReLateBound(debruijn, br) = *r { + if debruijn == self.current_index { + self.regions.insert(br); + } + } + false + } +} diff --git a/compiler/rustc_middle/src/ty/inhabitedness/def_id_forest.rs b/compiler/rustc_middle/src/ty/inhabitedness/def_id_forest.rs new file mode 100644 index 00000000000..ee6b06a1cc8 --- /dev/null +++ b/compiler/rustc_middle/src/ty/inhabitedness/def_id_forest.rs @@ -0,0 +1,113 @@ +use crate::ty::context::TyCtxt; +use crate::ty::{DefId, DefIdTree}; +use rustc_hir::CRATE_HIR_ID; +use smallvec::SmallVec; +use std::mem; + +/// Represents a forest of `DefId`s closed under the ancestor relation. That is, +/// if a `DefId` representing a module is contained in the forest then all +/// `DefId`s defined in that module or submodules are also implicitly contained +/// in the forest. +/// +/// This is used to represent a set of modules in which a type is visibly +/// uninhabited. +#[derive(Clone)] +pub struct DefIdForest { + /// The minimal set of `DefId`s required to represent the whole set. + /// If A and B are DefIds in the `DefIdForest`, and A is a descendant + /// of B, then only B will be in `root_ids`. + /// We use a `SmallVec` here because (for its use for caching inhabitedness) + /// its rare that this will contain even two IDs. + root_ids: SmallVec<[DefId; 1]>, +} + +impl<'tcx> DefIdForest { + /// Creates an empty forest. + pub fn empty() -> DefIdForest { + DefIdForest { root_ids: SmallVec::new() } + } + + /// Creates a forest consisting of a single tree representing the entire + /// crate. + #[inline] + pub fn full(tcx: TyCtxt<'tcx>) -> DefIdForest { + let crate_id = tcx.hir().local_def_id(CRATE_HIR_ID); + DefIdForest::from_id(crate_id.to_def_id()) + } + + /// Creates a forest containing a `DefId` and all its descendants. + pub fn from_id(id: DefId) -> DefIdForest { + let mut root_ids = SmallVec::new(); + root_ids.push(id); + DefIdForest { root_ids } + } + + /// Tests whether the forest is empty. + pub fn is_empty(&self) -> bool { + self.root_ids.is_empty() + } + + /// Tests whether the forest contains a given DefId. + pub fn contains(&self, tcx: TyCtxt<'tcx>, id: DefId) -> bool { + self.root_ids.iter().any(|root_id| tcx.is_descendant_of(id, *root_id)) + } + + /// Calculate the intersection of a collection of forests. + pub fn intersection<I>(tcx: TyCtxt<'tcx>, iter: I) -> DefIdForest + where + I: IntoIterator<Item = DefIdForest>, + { + let mut iter = iter.into_iter(); + let mut ret = if let Some(first) = iter.next() { + first + } else { + return DefIdForest::full(tcx); + }; + + let mut next_ret = SmallVec::new(); + let mut old_ret: SmallVec<[DefId; 1]> = SmallVec::new(); + for next_forest in iter { + // No need to continue if the intersection is already empty. + if ret.is_empty() { + break; + } + + for id in ret.root_ids.drain(..) { + if next_forest.contains(tcx, id) { + next_ret.push(id); + } else { + old_ret.push(id); + } + } + ret.root_ids.extend(old_ret.drain(..)); + + next_ret.extend(next_forest.root_ids.into_iter().filter(|&id| ret.contains(tcx, id))); + + mem::swap(&mut next_ret, &mut ret.root_ids); + next_ret.drain(..); + } + ret + } + + /// Calculate the union of a collection of forests. + pub fn union<I>(tcx: TyCtxt<'tcx>, iter: I) -> DefIdForest + where + I: IntoIterator<Item = DefIdForest>, + { + let mut ret = DefIdForest::empty(); + let mut next_ret = SmallVec::new(); + for next_forest in iter { + next_ret.extend(ret.root_ids.drain(..).filter(|&id| !next_forest.contains(tcx, id))); + + for id in next_forest.root_ids { + if !next_ret.contains(&id) { + next_ret.push(id); + } + } + + mem::swap(&mut next_ret, &mut ret.root_ids); + next_ret.drain(..); + } + ret + } +} diff --git a/compiler/rustc_middle/src/ty/inhabitedness/mod.rs b/compiler/rustc_middle/src/ty/inhabitedness/mod.rs new file mode 100644 index 00000000000..d1b5eed921b --- /dev/null +++ b/compiler/rustc_middle/src/ty/inhabitedness/mod.rs @@ -0,0 +1,228 @@ +pub use self::def_id_forest::DefIdForest; + +use crate::ty; +use crate::ty::context::TyCtxt; +use crate::ty::TyKind::*; +use crate::ty::{AdtDef, FieldDef, Ty, TyS, VariantDef}; +use crate::ty::{AdtKind, Visibility}; +use crate::ty::{DefId, SubstsRef}; +use rustc_data_structures::stack::ensure_sufficient_stack; + +mod def_id_forest; + +// The methods in this module calculate `DefIdForest`s of modules in which a +// `AdtDef`/`VariantDef`/`FieldDef` is visibly uninhabited. +// +// # Example +// ```rust +// enum Void {} +// mod a { +// pub mod b { +// pub struct SecretlyUninhabited { +// _priv: !, +// } +// } +// } +// +// mod c { +// pub struct AlsoSecretlyUninhabited { +// _priv: Void, +// } +// mod d { +// } +// } +// +// struct Foo { +// x: a::b::SecretlyUninhabited, +// y: c::AlsoSecretlyUninhabited, +// } +// ``` +// In this code, the type `Foo` will only be visibly uninhabited inside the +// modules `b`, `c` and `d`. Calling `uninhabited_from` on `Foo` or its `AdtDef` will +// return the forest of modules {`b`, `c`->`d`} (represented in a `DefIdForest` by the +// set {`b`, `c`}). +// +// We need this information for pattern-matching on `Foo` or types that contain +// `Foo`. +// +// # Example +// ```rust +// let foo_result: Result<T, Foo> = ... ; +// let Ok(t) = foo_result; +// ``` +// This code should only compile in modules where the uninhabitedness of `Foo` is +// visible. + +impl<'tcx> TyCtxt<'tcx> { + /// Checks whether a type is visibly uninhabited from a particular module. + /// + /// # Example + /// ```rust + /// enum Void {} + /// mod a { + /// pub mod b { + /// pub struct SecretlyUninhabited { + /// _priv: !, + /// } + /// } + /// } + /// + /// mod c { + /// pub struct AlsoSecretlyUninhabited { + /// _priv: Void, + /// } + /// mod d { + /// } + /// } + /// + /// struct Foo { + /// x: a::b::SecretlyUninhabited, + /// y: c::AlsoSecretlyUninhabited, + /// } + /// ``` + /// In this code, the type `Foo` will only be visibly uninhabited inside the + /// modules b, c and d. This effects pattern-matching on `Foo` or types that + /// contain `Foo`. + /// + /// # Example + /// ```rust + /// let foo_result: Result<T, Foo> = ... ; + /// let Ok(t) = foo_result; + /// ``` + /// This code should only compile in modules where the uninhabitedness of Foo is + /// visible. + pub fn is_ty_uninhabited_from( + self, + module: DefId, + ty: Ty<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> bool { + // To check whether this type is uninhabited at all (not just from the + // given node), you could check whether the forest is empty. + // ``` + // forest.is_empty() + // ``` + ty.uninhabited_from(self, param_env).contains(self, module) + } + + pub fn is_ty_uninhabited_from_any_module( + self, + ty: Ty<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> bool { + !ty.uninhabited_from(self, param_env).is_empty() + } +} + +impl<'tcx> AdtDef { + /// Calculates the forest of `DefId`s from which this ADT is visibly uninhabited. + fn uninhabited_from( + &self, + tcx: TyCtxt<'tcx>, + substs: SubstsRef<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> DefIdForest { + // Non-exhaustive ADTs from other crates are always considered inhabited. + if self.is_variant_list_non_exhaustive() && !self.did.is_local() { + DefIdForest::empty() + } else { + DefIdForest::intersection( + tcx, + self.variants + .iter() + .map(|v| v.uninhabited_from(tcx, substs, self.adt_kind(), param_env)), + ) + } + } +} + +impl<'tcx> VariantDef { + /// Calculates the forest of `DefId`s from which this variant is visibly uninhabited. + pub fn uninhabited_from( + &self, + tcx: TyCtxt<'tcx>, + substs: SubstsRef<'tcx>, + adt_kind: AdtKind, + param_env: ty::ParamEnv<'tcx>, + ) -> DefIdForest { + let is_enum = match adt_kind { + // For now, `union`s are never considered uninhabited. + // The precise semantics of inhabitedness with respect to unions is currently undecided. + AdtKind::Union => return DefIdForest::empty(), + AdtKind::Enum => true, + AdtKind::Struct => false, + }; + // Non-exhaustive variants from other crates are always considered inhabited. + if self.is_field_list_non_exhaustive() && !self.def_id.is_local() { + DefIdForest::empty() + } else { + DefIdForest::union( + tcx, + self.fields.iter().map(|f| f.uninhabited_from(tcx, substs, is_enum, param_env)), + ) + } + } +} + +impl<'tcx> FieldDef { + /// Calculates the forest of `DefId`s from which this field is visibly uninhabited. + fn uninhabited_from( + &self, + tcx: TyCtxt<'tcx>, + substs: SubstsRef<'tcx>, + is_enum: bool, + param_env: ty::ParamEnv<'tcx>, + ) -> DefIdForest { + let data_uninhabitedness = move || self.ty(tcx, substs).uninhabited_from(tcx, param_env); + // FIXME(canndrew): Currently enum fields are (incorrectly) stored with + // `Visibility::Invisible` so we need to override `self.vis` if we're + // dealing with an enum. + if is_enum { + data_uninhabitedness() + } else { + match self.vis { + Visibility::Invisible => DefIdForest::empty(), + Visibility::Restricted(from) => { + let forest = DefIdForest::from_id(from); + let iter = Some(forest).into_iter().chain(Some(data_uninhabitedness())); + DefIdForest::intersection(tcx, iter) + } + Visibility::Public => data_uninhabitedness(), + } + } + } +} + +impl<'tcx> TyS<'tcx> { + /// Calculates the forest of `DefId`s from which this type is visibly uninhabited. + fn uninhabited_from(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> DefIdForest { + match self.kind { + Adt(def, substs) => { + ensure_sufficient_stack(|| def.uninhabited_from(tcx, substs, param_env)) + } + + Never => DefIdForest::full(tcx), + + Tuple(ref tys) => DefIdForest::union( + tcx, + tys.iter().map(|ty| ty.expect_ty().uninhabited_from(tcx, param_env)), + ), + + Array(ty, len) => match len.try_eval_usize(tcx, param_env) { + // If the array is definitely non-empty, it's uninhabited if + // the type of its elements is uninhabited. + Some(n) if n != 0 => ty.uninhabited_from(tcx, param_env), + _ => DefIdForest::empty(), + }, + + // References to uninitialised memory is valid for any type, including + // uninhabited types, in unsafe code, so we treat all references as + // inhabited. + // The precise semantics of inhabitedness with respect to references is currently + // undecided. + Ref(..) => DefIdForest::empty(), + + _ => DefIdForest::empty(), + } + } +} diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs new file mode 100644 index 00000000000..8e08fe4b87b --- /dev/null +++ b/compiler/rustc_middle/src/ty/instance.rs @@ -0,0 +1,605 @@ +use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; +use crate::ty::print::{FmtPrinter, Printer}; +use crate::ty::subst::InternalSubsts; +use crate::ty::{self, SubstsRef, Ty, TyCtxt, TypeFoldable}; +use rustc_errors::ErrorReported; +use rustc_hir::def::Namespace; +use rustc_hir::def_id::{CrateNum, DefId}; +use rustc_hir::lang_items::LangItem; +use rustc_macros::HashStable; + +use std::fmt; + +/// A monomorphized `InstanceDef`. +/// +/// Monomorphization happens on-the-fly and no monomorphized MIR is ever created. Instead, this type +/// simply couples a potentially generic `InstanceDef` with some substs, and codegen and const eval +/// will do all required substitution as they run. +#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable, Lift)] +pub struct Instance<'tcx> { + pub def: InstanceDef<'tcx>, + pub substs: SubstsRef<'tcx>, +} + +#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum InstanceDef<'tcx> { + /// A user-defined callable item. + /// + /// This includes: + /// - `fn` items + /// - closures + /// - generators + Item(ty::WithOptConstParam<DefId>), + + /// An intrinsic `fn` item (with `"rust-intrinsic"` or `"platform-intrinsic"` ABI). + /// + /// Alongside `Virtual`, this is the only `InstanceDef` that does not have its own callable MIR. + /// Instead, codegen and const eval "magically" evaluate calls to intrinsics purely in the + /// caller. + Intrinsic(DefId), + + /// `<T as Trait>::method` where `method` receives unsizeable `self: Self` (part of the + /// `unsized_locals` feature). + /// + /// The generated shim will take `Self` via `*mut Self` - conceptually this is `&owned Self` - + /// and dereference the argument to call the original function. + VtableShim(DefId), + + /// `fn()` pointer where the function itself cannot be turned into a pointer. + /// + /// One example is `<dyn Trait as Trait>::fn`, where the shim contains + /// a virtual call, which codegen supports only via a direct call to the + /// `<dyn Trait as Trait>::fn` instance (an `InstanceDef::Virtual`). + /// + /// Another example is functions annotated with `#[track_caller]`, which + /// must have their implicit caller location argument populated for a call. + /// Because this is a required part of the function's ABI but can't be tracked + /// as a property of the function pointer, we use a single "caller location" + /// (the definition of the function itself). + ReifyShim(DefId), + + /// `<fn() as FnTrait>::call_*` (generated `FnTrait` implementation for `fn()` pointers). + /// + /// `DefId` is `FnTrait::call_*`. + /// + /// NB: the (`fn` pointer) type must currently be monomorphic to avoid double substitution + /// problems with the MIR shim bodies. `Instance::resolve` enforces this. + // FIXME(#69925) support polymorphic MIR shim bodies properly instead. + FnPtrShim(DefId, Ty<'tcx>), + + /// Dynamic dispatch to `<dyn Trait as Trait>::fn`. + /// + /// This `InstanceDef` does not have callable MIR. Calls to `Virtual` instances must be + /// codegen'd as virtual calls through the vtable. + /// + /// If this is reified to a `fn` pointer, a `ReifyShim` is used (see `ReifyShim` above for more + /// details on that). + Virtual(DefId, usize), + + /// `<[FnMut closure] as FnOnce>::call_once`. + /// + /// The `DefId` is the ID of the `call_once` method in `FnOnce`. + ClosureOnceShim { call_once: DefId }, + + /// `core::ptr::drop_in_place::<T>`. + /// + /// The `DefId` is for `core::ptr::drop_in_place`. + /// The `Option<Ty<'tcx>>` is either `Some(T)`, or `None` for empty drop + /// glue. + /// + /// NB: the type must currently be monomorphic to avoid double substitution + /// problems with the MIR shim bodies. `Instance::resolve` enforces this. + // FIXME(#69925) support polymorphic MIR shim bodies properly instead. + DropGlue(DefId, Option<Ty<'tcx>>), + + /// Compiler-generated `<T as Clone>::clone` implementation. + /// + /// For all types that automatically implement `Copy`, a trivial `Clone` impl is provided too. + /// Additionally, arrays, tuples, and closures get a `Clone` shim even if they aren't `Copy`. + /// + /// The `DefId` is for `Clone::clone`, the `Ty` is the type `T` with the builtin `Clone` impl. + /// + /// NB: the type must currently be monomorphic to avoid double substitution + /// problems with the MIR shim bodies. `Instance::resolve` enforces this. + // FIXME(#69925) support polymorphic MIR shim bodies properly instead. + CloneShim(DefId, Ty<'tcx>), +} + +impl<'tcx> Instance<'tcx> { + /// Returns the `Ty` corresponding to this `Instance`, with generic substitutions applied and + /// lifetimes erased, allowing a `ParamEnv` to be specified for use during normalization. + pub fn ty(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Ty<'tcx> { + let ty = tcx.type_of(self.def.def_id()); + tcx.subst_and_normalize_erasing_regions(self.substs, param_env, &ty) + } + + /// Finds a crate that contains a monomorphization of this instance that + /// can be linked to from the local crate. A return value of `None` means + /// no upstream crate provides such an exported monomorphization. + /// + /// This method already takes into account the global `-Zshare-generics` + /// setting, always returning `None` if `share-generics` is off. + pub fn upstream_monomorphization(&self, tcx: TyCtxt<'tcx>) -> Option<CrateNum> { + // If we are not in share generics mode, we don't link to upstream + // monomorphizations but always instantiate our own internal versions + // instead. + if !tcx.sess.opts.share_generics() { + return None; + } + + // If this is an item that is defined in the local crate, no upstream + // crate can know about it/provide a monomorphization. + if self.def_id().is_local() { + return None; + } + + // If this a non-generic instance, it cannot be a shared monomorphization. + self.substs.non_erasable_generics().next()?; + + match self.def { + InstanceDef::Item(def) => tcx + .upstream_monomorphizations_for(def.did) + .and_then(|monos| monos.get(&self.substs).cloned()), + InstanceDef::DropGlue(_, Some(_)) => tcx.upstream_drop_glue_for(self.substs), + _ => None, + } + } +} + +impl<'tcx> InstanceDef<'tcx> { + #[inline] + pub fn def_id(self) -> DefId { + match self { + InstanceDef::Item(def) => def.did, + InstanceDef::VtableShim(def_id) + | InstanceDef::ReifyShim(def_id) + | InstanceDef::FnPtrShim(def_id, _) + | InstanceDef::Virtual(def_id, _) + | InstanceDef::Intrinsic(def_id) + | InstanceDef::ClosureOnceShim { call_once: def_id } + | InstanceDef::DropGlue(def_id, _) + | InstanceDef::CloneShim(def_id, _) => def_id, + } + } + + #[inline] + pub fn with_opt_param(self) -> ty::WithOptConstParam<DefId> { + match self { + InstanceDef::Item(def) => def, + InstanceDef::VtableShim(def_id) + | InstanceDef::ReifyShim(def_id) + | InstanceDef::FnPtrShim(def_id, _) + | InstanceDef::Virtual(def_id, _) + | InstanceDef::Intrinsic(def_id) + | InstanceDef::ClosureOnceShim { call_once: def_id } + | InstanceDef::DropGlue(def_id, _) + | InstanceDef::CloneShim(def_id, _) => ty::WithOptConstParam::unknown(def_id), + } + } + + #[inline] + pub fn attrs(&self, tcx: TyCtxt<'tcx>) -> ty::Attributes<'tcx> { + tcx.get_attrs(self.def_id()) + } + + /// Returns `true` if the LLVM version of this instance is unconditionally + /// marked with `inline`. This implies that a copy of this instance is + /// generated in every codegen unit. + /// Note that this is only a hint. See the documentation for + /// `generates_cgu_internal_copy` for more information. + pub fn requires_inline(&self, tcx: TyCtxt<'tcx>) -> bool { + use rustc_hir::definitions::DefPathData; + let def_id = match *self { + ty::InstanceDef::Item(def) => def.did, + ty::InstanceDef::DropGlue(_, Some(_)) => return false, + _ => return true, + }; + match tcx.def_key(def_id).disambiguated_data.data { + DefPathData::Ctor | DefPathData::ClosureExpr => true, + _ => false, + } + } + + /// Returns `true` if the machine code for this instance is instantiated in + /// each codegen unit that references it. + /// Note that this is only a hint! The compiler can globally decide to *not* + /// do this in order to speed up compilation. CGU-internal copies are + /// only exist to enable inlining. If inlining is not performed (e.g. at + /// `-Copt-level=0`) then the time for generating them is wasted and it's + /// better to create a single copy with external linkage. + pub fn generates_cgu_internal_copy(&self, tcx: TyCtxt<'tcx>) -> bool { + if self.requires_inline(tcx) { + return true; + } + if let ty::InstanceDef::DropGlue(.., Some(ty)) = *self { + // Drop glue generally wants to be instantiated at every codegen + // unit, but without an #[inline] hint. We should make this + // available to normal end-users. + if tcx.sess.opts.incremental.is_none() { + return true; + } + // When compiling with incremental, we can generate a *lot* of + // codegen units. Including drop glue into all of them has a + // considerable compile time cost. + // + // We include enums without destructors to allow, say, optimizing + // drops of `Option::None` before LTO. We also respect the intent of + // `#[inline]` on `Drop::drop` implementations. + return ty.ty_adt_def().map_or(true, |adt_def| { + adt_def.destructor(tcx).map_or(adt_def.is_enum(), |dtor| { + tcx.codegen_fn_attrs(dtor.did).requests_inline() + }) + }); + } + tcx.codegen_fn_attrs(self.def_id()).requests_inline() + } + + pub fn requires_caller_location(&self, tcx: TyCtxt<'_>) -> bool { + match *self { + InstanceDef::Item(def) => { + tcx.codegen_fn_attrs(def.did).flags.contains(CodegenFnAttrFlags::TRACK_CALLER) + } + _ => false, + } + } +} + +impl<'tcx> fmt::Display for Instance<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + ty::tls::with(|tcx| { + let substs = tcx.lift(&self.substs).expect("could not lift for printing"); + FmtPrinter::new(tcx, &mut *f, Namespace::ValueNS) + .print_def_path(self.def_id(), substs)?; + Ok(()) + })?; + + match self.def { + InstanceDef::Item(_) => Ok(()), + InstanceDef::VtableShim(_) => write!(f, " - shim(vtable)"), + InstanceDef::ReifyShim(_) => write!(f, " - shim(reify)"), + InstanceDef::Intrinsic(_) => write!(f, " - intrinsic"), + InstanceDef::Virtual(_, num) => write!(f, " - virtual#{}", num), + InstanceDef::FnPtrShim(_, ty) => write!(f, " - shim({:?})", ty), + InstanceDef::ClosureOnceShim { .. } => write!(f, " - shim"), + InstanceDef::DropGlue(_, ty) => write!(f, " - shim({:?})", ty), + InstanceDef::CloneShim(_, ty) => write!(f, " - shim({:?})", ty), + } + } +} + +impl<'tcx> Instance<'tcx> { + pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> Instance<'tcx> { + assert!( + !substs.has_escaping_bound_vars(), + "substs of instance {:?} not normalized for codegen: {:?}", + def_id, + substs + ); + Instance { def: InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)), substs } + } + + pub fn mono(tcx: TyCtxt<'tcx>, def_id: DefId) -> Instance<'tcx> { + Instance::new(def_id, tcx.empty_substs_for_def_id(def_id)) + } + + #[inline] + pub fn def_id(&self) -> DefId { + self.def.def_id() + } + + /// Resolves a `(def_id, substs)` pair to an (optional) instance -- most commonly, + /// this is used to find the precise code that will run for a trait method invocation, + /// if known. + /// + /// Returns `Ok(None)` if we cannot resolve `Instance` to a specific instance. + /// For example, in a context like this, + /// + /// ``` + /// fn foo<T: Debug>(t: T) { ... } + /// ``` + /// + /// trying to resolve `Debug::fmt` applied to `T` will yield `Ok(None)`, because we do not + /// know what code ought to run. (Note that this setting is also affected by the + /// `RevealMode` in the parameter environment.) + /// + /// Presuming that coherence and type-check have succeeded, if this method is invoked + /// in a monomorphic context (i.e., like during codegen), then it is guaranteed to return + /// `Ok(Some(instance))`. + /// + /// Returns `Err(ErrorReported)` when the `Instance` resolution process + /// couldn't complete due to errors elsewhere - this is distinct + /// from `Ok(None)` to avoid misleading diagnostics when an error + /// has already been/will be emitted, for the original cause + pub fn resolve( + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + def_id: DefId, + substs: SubstsRef<'tcx>, + ) -> Result<Option<Instance<'tcx>>, ErrorReported> { + Instance::resolve_opt_const_arg( + tcx, + param_env, + ty::WithOptConstParam::unknown(def_id), + substs, + ) + } + + // This should be kept up to date with `resolve`. + pub fn resolve_opt_const_arg( + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + def: ty::WithOptConstParam<DefId>, + substs: SubstsRef<'tcx>, + ) -> Result<Option<Instance<'tcx>>, ErrorReported> { + // All regions in the result of this query are erased, so it's + // fine to erase all of the input regions. + + // HACK(eddyb) erase regions in `substs` first, so that `param_env.and(...)` + // below is more likely to ignore the bounds in scope (e.g. if the only + // generic parameters mentioned by `substs` were lifetime ones). + let substs = tcx.erase_regions(&substs); + + // FIXME(eddyb) should this always use `param_env.with_reveal_all()`? + if let Some((did, param_did)) = def.as_const_arg() { + tcx.resolve_instance_of_const_arg( + tcx.erase_regions(¶m_env.and((did, param_did, substs))), + ) + } else { + tcx.resolve_instance(tcx.erase_regions(¶m_env.and((def.did, substs)))) + } + } + + pub fn resolve_for_fn_ptr( + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + def_id: DefId, + substs: SubstsRef<'tcx>, + ) -> Option<Instance<'tcx>> { + debug!("resolve(def_id={:?}, substs={:?})", def_id, substs); + Instance::resolve(tcx, param_env, def_id, substs).ok().flatten().map(|mut resolved| { + match resolved.def { + InstanceDef::Item(def) if resolved.def.requires_caller_location(tcx) => { + debug!(" => fn pointer created for function with #[track_caller]"); + resolved.def = InstanceDef::ReifyShim(def.did); + } + InstanceDef::Virtual(def_id, _) => { + debug!(" => fn pointer created for virtual call"); + resolved.def = InstanceDef::ReifyShim(def_id); + } + _ => {} + } + + resolved + }) + } + + pub fn resolve_for_vtable( + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + def_id: DefId, + substs: SubstsRef<'tcx>, + ) -> Option<Instance<'tcx>> { + debug!("resolve(def_id={:?}, substs={:?})", def_id, substs); + let fn_sig = tcx.fn_sig(def_id); + let is_vtable_shim = !fn_sig.inputs().skip_binder().is_empty() + && fn_sig.input(0).skip_binder().is_param(0) + && tcx.generics_of(def_id).has_self; + if is_vtable_shim { + debug!(" => associated item with unsizeable self: Self"); + Some(Instance { def: InstanceDef::VtableShim(def_id), substs }) + } else { + Instance::resolve_for_fn_ptr(tcx, param_env, def_id, substs) + } + } + + pub fn resolve_closure( + tcx: TyCtxt<'tcx>, + def_id: DefId, + substs: ty::SubstsRef<'tcx>, + requested_kind: ty::ClosureKind, + ) -> Instance<'tcx> { + let actual_kind = substs.as_closure().kind(); + + match needs_fn_once_adapter_shim(actual_kind, requested_kind) { + Ok(true) => Instance::fn_once_adapter_instance(tcx, def_id, substs), + _ => Instance::new(def_id, substs), + } + } + + pub fn resolve_drop_in_place(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> ty::Instance<'tcx> { + let def_id = tcx.require_lang_item(LangItem::DropInPlace, None); + let substs = tcx.intern_substs(&[ty.into()]); + Instance::resolve(tcx, ty::ParamEnv::reveal_all(), def_id, substs).unwrap().unwrap() + } + + pub fn fn_once_adapter_instance( + tcx: TyCtxt<'tcx>, + closure_did: DefId, + substs: ty::SubstsRef<'tcx>, + ) -> Instance<'tcx> { + debug!("fn_once_adapter_shim({:?}, {:?})", closure_did, substs); + let fn_once = tcx.require_lang_item(LangItem::FnOnce, None); + let call_once = tcx + .associated_items(fn_once) + .in_definition_order() + .find(|it| it.kind == ty::AssocKind::Fn) + .unwrap() + .def_id; + let def = ty::InstanceDef::ClosureOnceShim { call_once }; + + let self_ty = tcx.mk_closure(closure_did, substs); + + let sig = substs.as_closure().sig(); + let sig = tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), &sig); + assert_eq!(sig.inputs().len(), 1); + let substs = tcx.mk_substs_trait(self_ty, &[sig.inputs()[0].into()]); + + debug!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty, sig); + Instance { def, substs } + } + + /// FIXME(#69925) Depending on the kind of `InstanceDef`, the MIR body associated with an + /// instance is expressed in terms of the generic parameters of `self.def_id()`, and in other + /// cases the MIR body is expressed in terms of the types found in the substitution array. + /// In the former case, we want to substitute those generic types and replace them with the + /// values from the substs when monomorphizing the function body. But in the latter case, we + /// don't want to do that substitution, since it has already been done effectively. + /// + /// This function returns `Some(substs)` in the former case and None otherwise -- i.e., if + /// this function returns `None`, then the MIR body does not require substitution during + /// monomorphization. + pub fn substs_for_mir_body(&self) -> Option<SubstsRef<'tcx>> { + match self.def { + InstanceDef::CloneShim(..) + | InstanceDef::DropGlue(_, Some(_)) => None, + InstanceDef::ClosureOnceShim { .. } + | InstanceDef::DropGlue(..) + // FIXME(#69925): `FnPtrShim` should be in the other branch. + | InstanceDef::FnPtrShim(..) + | InstanceDef::Item(_) + | InstanceDef::Intrinsic(..) + | InstanceDef::ReifyShim(..) + | InstanceDef::Virtual(..) + | InstanceDef::VtableShim(..) => Some(self.substs), + } + } + + /// Returns a new `Instance` where generic parameters in `instance.substs` are replaced by + /// identify parameters if they are determined to be unused in `instance.def`. + pub fn polymorphize(self, tcx: TyCtxt<'tcx>) -> Self { + debug!("polymorphize: running polymorphization analysis"); + if !tcx.sess.opts.debugging_opts.polymorphize { + return self; + } + + if let InstanceDef::Item(def) = self.def { + let polymorphized_substs = polymorphize(tcx, def.did, self.substs); + debug!("polymorphize: self={:?} polymorphized_substs={:?}", self, polymorphized_substs); + Self { def: self.def, substs: polymorphized_substs } + } else { + self + } + } +} + +fn polymorphize<'tcx>( + tcx: TyCtxt<'tcx>, + def_id: DefId, + substs: SubstsRef<'tcx>, +) -> SubstsRef<'tcx> { + debug!("polymorphize({:?}, {:?})", def_id, substs); + let unused = tcx.unused_generic_params(def_id); + debug!("polymorphize: unused={:?}", unused); + + // If this is a closure or generator then we need to handle the case where another closure + // from the function is captured as an upvar and hasn't been polymorphized. In this case, + // the unpolymorphized upvar closure would result in a polymorphized closure producing + // multiple mono items (and eventually symbol clashes). + let upvars_ty = if tcx.is_closure(def_id) { + Some(substs.as_closure().tupled_upvars_ty()) + } else if tcx.type_of(def_id).is_generator() { + Some(substs.as_generator().tupled_upvars_ty()) + } else { + None + }; + let has_upvars = upvars_ty.map(|ty| ty.tuple_fields().count() > 0).unwrap_or(false); + debug!("polymorphize: upvars_ty={:?} has_upvars={:?}", upvars_ty, has_upvars); + + struct PolymorphizationFolder<'tcx> { + tcx: TyCtxt<'tcx>, + }; + + impl ty::TypeFolder<'tcx> for PolymorphizationFolder<'tcx> { + fn tcx<'a>(&'a self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { + debug!("fold_ty: ty={:?}", ty); + match ty.kind { + ty::Closure(def_id, substs) => { + let polymorphized_substs = polymorphize(self.tcx, def_id, substs); + if substs == polymorphized_substs { + ty + } else { + self.tcx.mk_closure(def_id, polymorphized_substs) + } + } + ty::Generator(def_id, substs, movability) => { + let polymorphized_substs = polymorphize(self.tcx, def_id, substs); + if substs == polymorphized_substs { + ty + } else { + self.tcx.mk_generator(def_id, polymorphized_substs, movability) + } + } + _ => ty.super_fold_with(self), + } + } + } + + InternalSubsts::for_item(tcx, def_id, |param, _| { + let is_unused = unused.contains(param.index).unwrap_or(false); + debug!("polymorphize: param={:?} is_unused={:?}", param, is_unused); + match param.kind { + // Upvar case: If parameter is a type parameter.. + ty::GenericParamDefKind::Type { .. } if + // ..and has upvars.. + has_upvars && + // ..and this param has the same type as the tupled upvars.. + upvars_ty == Some(substs[param.index as usize].expect_ty()) => { + // ..then double-check that polymorphization marked it used.. + debug_assert!(!is_unused); + // ..and polymorphize any closures/generators captured as upvars. + let upvars_ty = upvars_ty.unwrap(); + let polymorphized_upvars_ty = upvars_ty.fold_with( + &mut PolymorphizationFolder { tcx }); + debug!("polymorphize: polymorphized_upvars_ty={:?}", polymorphized_upvars_ty); + ty::GenericArg::from(polymorphized_upvars_ty) + }, + + // Simple case: If parameter is a const or type parameter.. + ty::GenericParamDefKind::Const | ty::GenericParamDefKind::Type { .. } if + // ..and is within range and unused.. + unused.contains(param.index).unwrap_or(false) => + // ..then use the identity for this parameter. + tcx.mk_param_from_def(param), + + // Otherwise, use the parameter as before. + _ => substs[param.index as usize], + } + }) +} + +fn needs_fn_once_adapter_shim( + actual_closure_kind: ty::ClosureKind, + trait_closure_kind: ty::ClosureKind, +) -> Result<bool, ()> { + match (actual_closure_kind, trait_closure_kind) { + (ty::ClosureKind::Fn, ty::ClosureKind::Fn) + | (ty::ClosureKind::FnMut, ty::ClosureKind::FnMut) + | (ty::ClosureKind::FnOnce, ty::ClosureKind::FnOnce) => { + // No adapter needed. + Ok(false) + } + (ty::ClosureKind::Fn, ty::ClosureKind::FnMut) => { + // The closure fn `llfn` is a `fn(&self, ...)`. We want a + // `fn(&mut self, ...)`. In fact, at codegen time, these are + // basically the same thing, so we can just return llfn. + Ok(false) + } + (ty::ClosureKind::Fn | ty::ClosureKind::FnMut, ty::ClosureKind::FnOnce) => { + // The closure fn `llfn` is a `fn(&self, ...)` or `fn(&mut + // self, ...)`. We want a `fn(self, ...)`. We can produce + // this by doing something like: + // + // fn call_once(self, ...) { call_mut(&self, ...) } + // fn call_once(mut self, ...) { call_mut(&mut self, ...) } + // + // These are both the same at codegen time. + Ok(true) + } + (ty::ClosureKind::FnMut | ty::ClosureKind::FnOnce, _) => Err(()), + } +} diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs new file mode 100644 index 00000000000..08bd131565b --- /dev/null +++ b/compiler/rustc_middle/src/ty/layout.rs @@ -0,0 +1,2829 @@ +use crate::ich::StableHashingContext; +use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; +use crate::mir::{GeneratorLayout, GeneratorSavedLocal}; +use crate::ty::subst::Subst; +use crate::ty::{self, subst::SubstsRef, ReprOptions, Ty, TyCtxt, TypeFoldable}; + +use rustc_ast::{self as ast, IntTy, UintTy}; +use rustc_attr as attr; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_hir as hir; +use rustc_hir::lang_items::LangItem; +use rustc_index::bit_set::BitSet; +use rustc_index::vec::{Idx, IndexVec}; +use rustc_session::{DataTypeKind, FieldInfo, SizeKind, VariantInfo}; +use rustc_span::symbol::{Ident, Symbol}; +use rustc_span::DUMMY_SP; +use rustc_target::abi::call::{ + ArgAbi, ArgAttribute, ArgAttributes, Conv, FnAbi, PassMode, Reg, RegKind, +}; +use rustc_target::abi::*; +use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec, PanicStrategy}; + +use std::cmp; +use std::fmt; +use std::iter; +use std::mem; +use std::num::NonZeroUsize; +use std::ops::Bound; + +pub trait IntegerExt { + fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>, signed: bool) -> Ty<'tcx>; + fn from_attr<C: HasDataLayout>(cx: &C, ity: attr::IntType) -> Integer; + fn repr_discr<'tcx>( + tcx: TyCtxt<'tcx>, + ty: Ty<'tcx>, + repr: &ReprOptions, + min: i128, + max: i128, + ) -> (Integer, bool); +} + +impl IntegerExt for Integer { + fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>, signed: bool) -> Ty<'tcx> { + match (*self, signed) { + (I8, false) => tcx.types.u8, + (I16, false) => tcx.types.u16, + (I32, false) => tcx.types.u32, + (I64, false) => tcx.types.u64, + (I128, false) => tcx.types.u128, + (I8, true) => tcx.types.i8, + (I16, true) => tcx.types.i16, + (I32, true) => tcx.types.i32, + (I64, true) => tcx.types.i64, + (I128, true) => tcx.types.i128, + } + } + + /// Gets the Integer type from an attr::IntType. + fn from_attr<C: HasDataLayout>(cx: &C, ity: attr::IntType) -> Integer { + let dl = cx.data_layout(); + + match ity { + attr::SignedInt(IntTy::I8) | attr::UnsignedInt(UintTy::U8) => I8, + attr::SignedInt(IntTy::I16) | attr::UnsignedInt(UintTy::U16) => I16, + attr::SignedInt(IntTy::I32) | attr::UnsignedInt(UintTy::U32) => I32, + attr::SignedInt(IntTy::I64) | attr::UnsignedInt(UintTy::U64) => I64, + attr::SignedInt(IntTy::I128) | attr::UnsignedInt(UintTy::U128) => I128, + attr::SignedInt(IntTy::Isize) | attr::UnsignedInt(UintTy::Usize) => { + dl.ptr_sized_integer() + } + } + } + + /// Finds the appropriate Integer type and signedness for the given + /// signed discriminant range and `#[repr]` attribute. + /// N.B.: `u128` values above `i128::MAX` will be treated as signed, but + /// that shouldn't affect anything, other than maybe debuginfo. + fn repr_discr<'tcx>( + tcx: TyCtxt<'tcx>, + ty: Ty<'tcx>, + repr: &ReprOptions, + min: i128, + max: i128, + ) -> (Integer, bool) { + // Theoretically, negative values could be larger in unsigned representation + // than the unsigned representation of the signed minimum. However, if there + // are any negative values, the only valid unsigned representation is u128 + // which can fit all i128 values, so the result remains unaffected. + let unsigned_fit = Integer::fit_unsigned(cmp::max(min as u128, max as u128)); + let signed_fit = cmp::max(Integer::fit_signed(min), Integer::fit_signed(max)); + + let mut min_from_extern = None; + let min_default = I8; + + if let Some(ity) = repr.int { + let discr = Integer::from_attr(&tcx, ity); + let fit = if ity.is_signed() { signed_fit } else { unsigned_fit }; + if discr < fit { + bug!( + "Integer::repr_discr: `#[repr]` hint too small for \ + discriminant range of enum `{}", + ty + ) + } + return (discr, ity.is_signed()); + } + + if repr.c() { + match &tcx.sess.target.target.arch[..] { + // WARNING: the ARM EABI has two variants; the one corresponding + // to `at_least == I32` appears to be used on Linux and NetBSD, + // but some systems may use the variant corresponding to no + // lower bound. However, we don't run on those yet...? + "arm" => min_from_extern = Some(I32), + _ => min_from_extern = Some(I32), + } + } + + let at_least = min_from_extern.unwrap_or(min_default); + + // If there are no negative values, we can use the unsigned fit. + if min >= 0 { + (cmp::max(unsigned_fit, at_least), false) + } else { + (cmp::max(signed_fit, at_least), true) + } + } +} + +pub trait PrimitiveExt { + fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx>; + fn to_int_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx>; +} + +impl PrimitiveExt for Primitive { + fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + match *self { + Int(i, signed) => i.to_ty(tcx, signed), + F32 => tcx.types.f32, + F64 => tcx.types.f64, + Pointer => tcx.mk_mut_ptr(tcx.mk_unit()), + } + } + + /// Return an *integer* type matching this primitive. + /// Useful in particular when dealing with enum discriminants. + fn to_int_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + match *self { + Int(i, signed) => i.to_ty(tcx, signed), + Pointer => tcx.types.usize, + F32 | F64 => bug!("floats do not have an int type"), + } + } +} + +/// The first half of a fat pointer. +/// +/// - For a trait object, this is the address of the box. +/// - For a slice, this is the base address. +pub const FAT_PTR_ADDR: usize = 0; + +/// The second half of a fat pointer. +/// +/// - For a trait object, this is the address of the vtable. +/// - For a slice, this is the length. +pub const FAT_PTR_EXTRA: usize = 1; + +#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable)] +pub enum LayoutError<'tcx> { + Unknown(Ty<'tcx>), + SizeOverflow(Ty<'tcx>), +} + +impl<'tcx> fmt::Display for LayoutError<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + LayoutError::Unknown(ty) => write!(f, "the type `{:?}` has an unknown layout", ty), + LayoutError::SizeOverflow(ty) => { + write!(f, "the type `{:?}` is too big for the current architecture", ty) + } + } + } +} + +fn layout_raw<'tcx>( + tcx: TyCtxt<'tcx>, + query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, +) -> Result<&'tcx Layout, LayoutError<'tcx>> { + ty::tls::with_related_context(tcx, move |icx| { + let (param_env, ty) = query.into_parts(); + + if !tcx.sess.recursion_limit().value_within_limit(icx.layout_depth) { + tcx.sess.fatal(&format!("overflow representing the type `{}`", ty)); + } + + // Update the ImplicitCtxt to increase the layout_depth + let icx = ty::tls::ImplicitCtxt { layout_depth: icx.layout_depth + 1, ..icx.clone() }; + + ty::tls::enter_context(&icx, |_| { + let cx = LayoutCx { tcx, param_env }; + let layout = cx.layout_raw_uncached(ty); + // Type-level uninhabitedness should always imply ABI uninhabitedness. + if let Ok(layout) = layout { + if ty.conservative_is_privately_uninhabited(tcx) { + assert!(layout.abi.is_uninhabited()); + } + } + layout + }) + }) +} + +pub fn provide(providers: &mut ty::query::Providers) { + *providers = ty::query::Providers { layout_raw, ..*providers }; +} + +pub struct LayoutCx<'tcx, C> { + pub tcx: C, + pub param_env: ty::ParamEnv<'tcx>, +} + +#[derive(Copy, Clone, Debug)] +enum StructKind { + /// A tuple, closure, or univariant which cannot be coerced to unsized. + AlwaysSized, + /// A univariant, the last field of which may be coerced to unsized. + MaybeUnsized, + /// A univariant, but with a prefix of an arbitrary size & alignment (e.g., enum tag). + Prefixed(Size, Align), +} + +// Invert a bijective mapping, i.e. `invert(map)[y] = x` if `map[x] = y`. +// This is used to go between `memory_index` (source field order to memory order) +// and `inverse_memory_index` (memory order to source field order). +// See also `FieldsShape::Arbitrary::memory_index` for more details. +// FIXME(eddyb) build a better abstraction for permutations, if possible. +fn invert_mapping(map: &[u32]) -> Vec<u32> { + let mut inverse = vec![0; map.len()]; + for i in 0..map.len() { + inverse[map[i] as usize] = i as u32; + } + inverse +} + +impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { + fn scalar_pair(&self, a: Scalar, b: Scalar) -> Layout { + let dl = self.data_layout(); + let b_align = b.value.align(dl); + let align = a.value.align(dl).max(b_align).max(dl.aggregate_align); + let b_offset = a.value.size(dl).align_to(b_align.abi); + let size = (b_offset + b.value.size(dl)).align_to(align.abi); + + // HACK(nox): We iter on `b` and then `a` because `max_by_key` + // returns the last maximum. + let largest_niche = Niche::from_scalar(dl, b_offset, b.clone()) + .into_iter() + .chain(Niche::from_scalar(dl, Size::ZERO, a.clone())) + .max_by_key(|niche| niche.available(dl)); + + Layout { + variants: Variants::Single { index: VariantIdx::new(0) }, + fields: FieldsShape::Arbitrary { + offsets: vec![Size::ZERO, b_offset], + memory_index: vec![0, 1], + }, + abi: Abi::ScalarPair(a, b), + largest_niche, + align, + size, + } + } + + fn univariant_uninterned( + &self, + ty: Ty<'tcx>, + fields: &[TyAndLayout<'_>], + repr: &ReprOptions, + kind: StructKind, + ) -> Result<Layout, LayoutError<'tcx>> { + let dl = self.data_layout(); + let pack = repr.pack; + if pack.is_some() && repr.align.is_some() { + bug!("struct cannot be packed and aligned"); + } + + let mut align = if pack.is_some() { dl.i8_align } else { dl.aggregate_align }; + + let mut inverse_memory_index: Vec<u32> = (0..fields.len() as u32).collect(); + + let optimize = !repr.inhibit_struct_field_reordering_opt(); + if optimize { + let end = + if let StructKind::MaybeUnsized = kind { fields.len() - 1 } else { fields.len() }; + let optimizing = &mut inverse_memory_index[..end]; + let field_align = |f: &TyAndLayout<'_>| { + if let Some(pack) = pack { f.align.abi.min(pack) } else { f.align.abi } + }; + match kind { + StructKind::AlwaysSized | StructKind::MaybeUnsized => { + optimizing.sort_by_key(|&x| { + // Place ZSTs first to avoid "interesting offsets", + // especially with only one or two non-ZST fields. + let f = &fields[x as usize]; + (!f.is_zst(), cmp::Reverse(field_align(f))) + }); + } + StructKind::Prefixed(..) => { + // Sort in ascending alignment so that the layout stay optimal + // regardless of the prefix + optimizing.sort_by_key(|&x| field_align(&fields[x as usize])); + } + } + } + + // inverse_memory_index holds field indices by increasing memory offset. + // That is, if field 5 has offset 0, the first element of inverse_memory_index is 5. + // We now write field offsets to the corresponding offset slot; + // field 5 with offset 0 puts 0 in offsets[5]. + // At the bottom of this function, we invert `inverse_memory_index` to + // produce `memory_index` (see `invert_mapping`). + + let mut sized = true; + let mut offsets = vec![Size::ZERO; fields.len()]; + let mut offset = Size::ZERO; + let mut largest_niche = None; + let mut largest_niche_available = 0; + + if let StructKind::Prefixed(prefix_size, prefix_align) = kind { + let prefix_align = + if let Some(pack) = pack { prefix_align.min(pack) } else { prefix_align }; + align = align.max(AbiAndPrefAlign::new(prefix_align)); + offset = prefix_size.align_to(prefix_align); + } + + for &i in &inverse_memory_index { + let field = fields[i as usize]; + if !sized { + bug!("univariant: field #{} of `{}` comes after unsized field", offsets.len(), ty); + } + + if field.is_unsized() { + sized = false; + } + + // Invariant: offset < dl.obj_size_bound() <= 1<<61 + let field_align = if let Some(pack) = pack { + field.align.min(AbiAndPrefAlign::new(pack)) + } else { + field.align + }; + offset = offset.align_to(field_align.abi); + align = align.max(field_align); + + debug!("univariant offset: {:?} field: {:#?}", offset, field); + offsets[i as usize] = offset; + + if !repr.hide_niche() { + if let Some(mut niche) = field.largest_niche.clone() { + let available = niche.available(dl); + if available > largest_niche_available { + largest_niche_available = available; + niche.offset += offset; + largest_niche = Some(niche); + } + } + } + + offset = offset.checked_add(field.size, dl).ok_or(LayoutError::SizeOverflow(ty))?; + } + + if let Some(repr_align) = repr.align { + align = align.max(AbiAndPrefAlign::new(repr_align)); + } + + debug!("univariant min_size: {:?}", offset); + let min_size = offset; + + // As stated above, inverse_memory_index holds field indices by increasing offset. + // This makes it an already-sorted view of the offsets vec. + // To invert it, consider: + // If field 5 has offset 0, offsets[0] is 5, and memory_index[5] should be 0. + // Field 5 would be the first element, so memory_index is i: + // Note: if we didn't optimize, it's already right. + + let memory_index = + if optimize { invert_mapping(&inverse_memory_index) } else { inverse_memory_index }; + + let size = min_size.align_to(align.abi); + let mut abi = Abi::Aggregate { sized }; + + // Unpack newtype ABIs and find scalar pairs. + if sized && size.bytes() > 0 { + // All other fields must be ZSTs, and we need them to all start at 0. + let mut zst_offsets = offsets.iter().enumerate().filter(|&(i, _)| fields[i].is_zst()); + if zst_offsets.all(|(_, o)| o.bytes() == 0) { + let mut non_zst_fields = fields.iter().enumerate().filter(|&(_, f)| !f.is_zst()); + + match (non_zst_fields.next(), non_zst_fields.next(), non_zst_fields.next()) { + // We have exactly one non-ZST field. + (Some((i, field)), None, None) => { + // Field fills the struct and it has a scalar or scalar pair ABI. + if offsets[i].bytes() == 0 + && align.abi == field.align.abi + && size == field.size + { + match field.abi { + // For plain scalars, or vectors of them, we can't unpack + // newtypes for `#[repr(C)]`, as that affects C ABIs. + Abi::Scalar(_) | Abi::Vector { .. } if optimize => { + abi = field.abi.clone(); + } + // But scalar pairs are Rust-specific and get + // treated as aggregates by C ABIs anyway. + Abi::ScalarPair(..) => { + abi = field.abi.clone(); + } + _ => {} + } + } + } + + // Two non-ZST fields, and they're both scalars. + ( + Some(( + i, + &TyAndLayout { + layout: &Layout { abi: Abi::Scalar(ref a), .. }, .. + }, + )), + Some(( + j, + &TyAndLayout { + layout: &Layout { abi: Abi::Scalar(ref b), .. }, .. + }, + )), + None, + ) => { + // Order by the memory placement, not source order. + let ((i, a), (j, b)) = if offsets[i] < offsets[j] { + ((i, a), (j, b)) + } else { + ((j, b), (i, a)) + }; + let pair = self.scalar_pair(a.clone(), b.clone()); + let pair_offsets = match pair.fields { + FieldsShape::Arbitrary { ref offsets, ref memory_index } => { + assert_eq!(memory_index, &[0, 1]); + offsets + } + _ => bug!(), + }; + if offsets[i] == pair_offsets[0] + && offsets[j] == pair_offsets[1] + && align == pair.align + && size == pair.size + { + // We can use `ScalarPair` only when it matches our + // already computed layout (including `#[repr(C)]`). + abi = pair.abi; + } + } + + _ => {} + } + } + } + + if sized && fields.iter().any(|f| f.abi.is_uninhabited()) { + abi = Abi::Uninhabited; + } + + Ok(Layout { + variants: Variants::Single { index: VariantIdx::new(0) }, + fields: FieldsShape::Arbitrary { offsets, memory_index }, + abi, + largest_niche, + align, + size, + }) + } + + fn layout_raw_uncached(&self, ty: Ty<'tcx>) -> Result<&'tcx Layout, LayoutError<'tcx>> { + let tcx = self.tcx; + let param_env = self.param_env; + let dl = self.data_layout(); + let scalar_unit = |value: Primitive| { + let bits = value.size(dl).bits(); + assert!(bits <= 128); + Scalar { value, valid_range: 0..=(!0 >> (128 - bits)) } + }; + let scalar = |value: Primitive| tcx.intern_layout(Layout::scalar(self, scalar_unit(value))); + + let univariant = |fields: &[TyAndLayout<'_>], repr: &ReprOptions, kind| { + Ok(tcx.intern_layout(self.univariant_uninterned(ty, fields, repr, kind)?)) + }; + debug_assert!(!ty.has_infer_types_or_consts()); + + Ok(match ty.kind { + // Basic scalars. + ty::Bool => tcx.intern_layout(Layout::scalar( + self, + Scalar { value: Int(I8, false), valid_range: 0..=1 }, + )), + ty::Char => tcx.intern_layout(Layout::scalar( + self, + Scalar { value: Int(I32, false), valid_range: 0..=0x10FFFF }, + )), + ty::Int(ity) => scalar(Int(Integer::from_attr(dl, attr::SignedInt(ity)), true)), + ty::Uint(ity) => scalar(Int(Integer::from_attr(dl, attr::UnsignedInt(ity)), false)), + ty::Float(fty) => scalar(match fty { + ast::FloatTy::F32 => F32, + ast::FloatTy::F64 => F64, + }), + ty::FnPtr(_) => { + let mut ptr = scalar_unit(Pointer); + ptr.valid_range = 1..=*ptr.valid_range.end(); + tcx.intern_layout(Layout::scalar(self, ptr)) + } + + // The never type. + ty::Never => tcx.intern_layout(Layout { + variants: Variants::Single { index: VariantIdx::new(0) }, + fields: FieldsShape::Primitive, + abi: Abi::Uninhabited, + largest_niche: None, + align: dl.i8_align, + size: Size::ZERO, + }), + + // Potentially-wide pointers. + ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => { + let mut data_ptr = scalar_unit(Pointer); + if !ty.is_unsafe_ptr() { + data_ptr.valid_range = 1..=*data_ptr.valid_range.end(); + } + + let pointee = tcx.normalize_erasing_regions(param_env, pointee); + if pointee.is_sized(tcx.at(DUMMY_SP), param_env) { + return Ok(tcx.intern_layout(Layout::scalar(self, data_ptr))); + } + + let unsized_part = tcx.struct_tail_erasing_lifetimes(pointee, param_env); + let metadata = match unsized_part.kind { + ty::Foreign(..) => { + return Ok(tcx.intern_layout(Layout::scalar(self, data_ptr))); + } + ty::Slice(_) | ty::Str => scalar_unit(Int(dl.ptr_sized_integer(), false)), + ty::Dynamic(..) => { + let mut vtable = scalar_unit(Pointer); + vtable.valid_range = 1..=*vtable.valid_range.end(); + vtable + } + _ => return Err(LayoutError::Unknown(unsized_part)), + }; + + // Effectively a (ptr, meta) tuple. + tcx.intern_layout(self.scalar_pair(data_ptr, metadata)) + } + + // Arrays and slices. + ty::Array(element, mut count) => { + if count.has_projections() { + count = tcx.normalize_erasing_regions(param_env, count); + if count.has_projections() { + return Err(LayoutError::Unknown(ty)); + } + } + + let count = count.try_eval_usize(tcx, param_env).ok_or(LayoutError::Unknown(ty))?; + let element = self.layout_of(element)?; + let size = + element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow(ty))?; + + let abi = if count != 0 && ty.conservative_is_privately_uninhabited(tcx) { + Abi::Uninhabited + } else { + Abi::Aggregate { sized: true } + }; + + let largest_niche = if count != 0 { element.largest_niche.clone() } else { None }; + + tcx.intern_layout(Layout { + variants: Variants::Single { index: VariantIdx::new(0) }, + fields: FieldsShape::Array { stride: element.size, count }, + abi, + largest_niche, + align: element.align, + size, + }) + } + ty::Slice(element) => { + let element = self.layout_of(element)?; + tcx.intern_layout(Layout { + variants: Variants::Single { index: VariantIdx::new(0) }, + fields: FieldsShape::Array { stride: element.size, count: 0 }, + abi: Abi::Aggregate { sized: false }, + largest_niche: None, + align: element.align, + size: Size::ZERO, + }) + } + ty::Str => tcx.intern_layout(Layout { + variants: Variants::Single { index: VariantIdx::new(0) }, + fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 }, + abi: Abi::Aggregate { sized: false }, + largest_niche: None, + align: dl.i8_align, + size: Size::ZERO, + }), + + // Odd unit types. + ty::FnDef(..) => univariant(&[], &ReprOptions::default(), StructKind::AlwaysSized)?, + ty::Dynamic(..) | ty::Foreign(..) => { + let mut unit = self.univariant_uninterned( + ty, + &[], + &ReprOptions::default(), + StructKind::AlwaysSized, + )?; + match unit.abi { + Abi::Aggregate { ref mut sized } => *sized = false, + _ => bug!(), + } + tcx.intern_layout(unit) + } + + ty::Generator(def_id, substs, _) => self.generator_layout(ty, def_id, substs)?, + + ty::Closure(_, ref substs) => { + let tys = substs.as_closure().upvar_tys(); + univariant( + &tys.map(|ty| self.layout_of(ty)).collect::<Result<Vec<_>, _>>()?, + &ReprOptions::default(), + StructKind::AlwaysSized, + )? + } + + ty::Tuple(tys) => { + let kind = + if tys.len() == 0 { StructKind::AlwaysSized } else { StructKind::MaybeUnsized }; + + univariant( + &tys.iter() + .map(|k| self.layout_of(k.expect_ty())) + .collect::<Result<Vec<_>, _>>()?, + &ReprOptions::default(), + kind, + )? + } + + // SIMD vector types. + ty::Adt(def, ..) if def.repr.simd() => { + let element = self.layout_of(ty.simd_type(tcx))?; + let count = ty.simd_size(tcx); + assert!(count > 0); + let scalar = match element.abi { + Abi::Scalar(ref scalar) => scalar.clone(), + _ => { + tcx.sess.fatal(&format!( + "monomorphising SIMD type `{}` with \ + a non-machine element type `{}`", + ty, element.ty + )); + } + }; + let size = + element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow(ty))?; + let align = dl.vector_align(size); + let size = size.align_to(align.abi); + + tcx.intern_layout(Layout { + variants: Variants::Single { index: VariantIdx::new(0) }, + fields: FieldsShape::Array { stride: element.size, count }, + abi: Abi::Vector { element: scalar, count }, + largest_niche: element.largest_niche.clone(), + size, + align, + }) + } + + // ADTs. + ty::Adt(def, substs) => { + // Cache the field layouts. + let variants = def + .variants + .iter() + .map(|v| { + v.fields + .iter() + .map(|field| self.layout_of(field.ty(tcx, substs))) + .collect::<Result<Vec<_>, _>>() + }) + .collect::<Result<IndexVec<VariantIdx, _>, _>>()?; + + if def.is_union() { + if def.repr.pack.is_some() && def.repr.align.is_some() { + bug!("union cannot be packed and aligned"); + } + + let mut align = + if def.repr.pack.is_some() { dl.i8_align } else { dl.aggregate_align }; + + if let Some(repr_align) = def.repr.align { + align = align.max(AbiAndPrefAlign::new(repr_align)); + } + + let optimize = !def.repr.inhibit_union_abi_opt(); + let mut size = Size::ZERO; + let mut abi = Abi::Aggregate { sized: true }; + let index = VariantIdx::new(0); + for field in &variants[index] { + assert!(!field.is_unsized()); + align = align.max(field.align); + + // If all non-ZST fields have the same ABI, forward this ABI + if optimize && !field.is_zst() { + // Normalize scalar_unit to the maximal valid range + let field_abi = match &field.abi { + Abi::Scalar(x) => Abi::Scalar(scalar_unit(x.value)), + Abi::ScalarPair(x, y) => { + Abi::ScalarPair(scalar_unit(x.value), scalar_unit(y.value)) + } + Abi::Vector { element: x, count } => { + Abi::Vector { element: scalar_unit(x.value), count: *count } + } + Abi::Uninhabited | Abi::Aggregate { .. } => { + Abi::Aggregate { sized: true } + } + }; + + if size == Size::ZERO { + // first non ZST: initialize 'abi' + abi = field_abi; + } else if abi != field_abi { + // different fields have different ABI: reset to Aggregate + abi = Abi::Aggregate { sized: true }; + } + } + + size = cmp::max(size, field.size); + } + + if let Some(pack) = def.repr.pack { + align = align.min(AbiAndPrefAlign::new(pack)); + } + + return Ok(tcx.intern_layout(Layout { + variants: Variants::Single { index }, + fields: FieldsShape::Union( + NonZeroUsize::new(variants[index].len()) + .ok_or(LayoutError::Unknown(ty))?, + ), + abi, + largest_niche: None, + align, + size: size.align_to(align.abi), + })); + } + + // A variant is absent if it's uninhabited and only has ZST fields. + // Present uninhabited variants only require space for their fields, + // but *not* an encoding of the discriminant (e.g., a tag value). + // See issue #49298 for more details on the need to leave space + // for non-ZST uninhabited data (mostly partial initialization). + let absent = |fields: &[TyAndLayout<'_>]| { + let uninhabited = fields.iter().any(|f| f.abi.is_uninhabited()); + let is_zst = fields.iter().all(|f| f.is_zst()); + uninhabited && is_zst + }; + let (present_first, present_second) = { + let mut present_variants = variants + .iter_enumerated() + .filter_map(|(i, v)| if absent(v) { None } else { Some(i) }); + (present_variants.next(), present_variants.next()) + }; + let present_first = match present_first { + Some(present_first) => present_first, + // Uninhabited because it has no variants, or only absent ones. + None if def.is_enum() => return tcx.layout_raw(param_env.and(tcx.types.never)), + // If it's a struct, still compute a layout so that we can still compute the + // field offsets. + None => VariantIdx::new(0), + }; + + let is_struct = !def.is_enum() || + // Only one variant is present. + (present_second.is_none() && + // Representation optimizations are allowed. + !def.repr.inhibit_enum_layout_opt()); + if is_struct { + // Struct, or univariant enum equivalent to a struct. + // (Typechecking will reject discriminant-sizing attrs.) + + let v = present_first; + let kind = if def.is_enum() || variants[v].is_empty() { + StructKind::AlwaysSized + } else { + let param_env = tcx.param_env(def.did); + let last_field = def.variants[v].fields.last().unwrap(); + let always_sized = + tcx.type_of(last_field.did).is_sized(tcx.at(DUMMY_SP), param_env); + if !always_sized { + StructKind::MaybeUnsized + } else { + StructKind::AlwaysSized + } + }; + + let mut st = self.univariant_uninterned(ty, &variants[v], &def.repr, kind)?; + st.variants = Variants::Single { index: v }; + let (start, end) = self.tcx.layout_scalar_valid_range(def.did); + match st.abi { + Abi::Scalar(ref mut scalar) | Abi::ScalarPair(ref mut scalar, _) => { + // the asserts ensure that we are not using the + // `#[rustc_layout_scalar_valid_range(n)]` + // attribute to widen the range of anything as that would probably + // result in UB somewhere + // FIXME(eddyb) the asserts are probably not needed, + // as larger validity ranges would result in missed + // optimizations, *not* wrongly assuming the inner + // value is valid. e.g. unions enlarge validity ranges, + // because the values may be uninitialized. + if let Bound::Included(start) = start { + // FIXME(eddyb) this might be incorrect - it doesn't + // account for wrap-around (end < start) ranges. + assert!(*scalar.valid_range.start() <= start); + scalar.valid_range = start..=*scalar.valid_range.end(); + } + if let Bound::Included(end) = end { + // FIXME(eddyb) this might be incorrect - it doesn't + // account for wrap-around (end < start) ranges. + assert!(*scalar.valid_range.end() >= end); + scalar.valid_range = *scalar.valid_range.start()..=end; + } + + // Update `largest_niche` if we have introduced a larger niche. + let niche = if def.repr.hide_niche() { + None + } else { + Niche::from_scalar(dl, Size::ZERO, scalar.clone()) + }; + if let Some(niche) = niche { + match &st.largest_niche { + Some(largest_niche) => { + // Replace the existing niche even if they're equal, + // because this one is at a lower offset. + if largest_niche.available(dl) <= niche.available(dl) { + st.largest_niche = Some(niche); + } + } + None => st.largest_niche = Some(niche), + } + } + } + _ => assert!( + start == Bound::Unbounded && end == Bound::Unbounded, + "nonscalar layout for layout_scalar_valid_range type {:?}: {:#?}", + def, + st, + ), + } + + return Ok(tcx.intern_layout(st)); + } + + // At this point, we have handled all unions and + // structs. (We have also handled univariant enums + // that allow representation optimization.) + assert!(def.is_enum()); + + // The current code for niche-filling relies on variant indices + // instead of actual discriminants, so dataful enums with + // explicit discriminants (RFC #2363) would misbehave. + let no_explicit_discriminants = def + .variants + .iter_enumerated() + .all(|(i, v)| v.discr == ty::VariantDiscr::Relative(i.as_u32())); + + let mut niche_filling_layout = None; + + // Niche-filling enum optimization. + if !def.repr.inhibit_enum_layout_opt() && no_explicit_discriminants { + let mut dataful_variant = None; + let mut niche_variants = VariantIdx::MAX..=VariantIdx::new(0); + + // Find one non-ZST variant. + 'variants: for (v, fields) in variants.iter_enumerated() { + if absent(fields) { + continue 'variants; + } + for f in fields { + if !f.is_zst() { + if dataful_variant.is_none() { + dataful_variant = Some(v); + continue 'variants; + } else { + dataful_variant = None; + break 'variants; + } + } + } + niche_variants = *niche_variants.start().min(&v)..=v; + } + + if niche_variants.start() > niche_variants.end() { + dataful_variant = None; + } + + if let Some(i) = dataful_variant { + let count = (niche_variants.end().as_u32() + - niche_variants.start().as_u32() + + 1) as u128; + + // Find the field with the largest niche + let niche_candidate = variants[i] + .iter() + .enumerate() + .filter_map(|(j, &field)| Some((j, field.largest_niche.as_ref()?))) + .max_by_key(|(_, niche)| niche.available(dl)); + + if let Some((field_index, niche, (niche_start, niche_scalar))) = + niche_candidate.and_then(|(field_index, niche)| { + Some((field_index, niche, niche.reserve(self, count)?)) + }) + { + let mut align = dl.aggregate_align; + let st = variants + .iter_enumerated() + .map(|(j, v)| { + let mut st = self.univariant_uninterned( + ty, + v, + &def.repr, + StructKind::AlwaysSized, + )?; + st.variants = Variants::Single { index: j }; + + align = align.max(st.align); + + Ok(st) + }) + .collect::<Result<IndexVec<VariantIdx, _>, _>>()?; + + let offset = st[i].fields.offset(field_index) + niche.offset; + let size = st[i].size; + + let abi = if st.iter().all(|v| v.abi.is_uninhabited()) { + Abi::Uninhabited + } else { + match st[i].abi { + Abi::Scalar(_) => Abi::Scalar(niche_scalar.clone()), + Abi::ScalarPair(ref first, ref second) => { + // We need to use scalar_unit to reset the + // valid range to the maximal one for that + // primitive, because only the niche is + // guaranteed to be initialised, not the + // other primitive. + if offset.bytes() == 0 { + Abi::ScalarPair( + niche_scalar.clone(), + scalar_unit(second.value), + ) + } else { + Abi::ScalarPair( + scalar_unit(first.value), + niche_scalar.clone(), + ) + } + } + _ => Abi::Aggregate { sized: true }, + } + }; + + let largest_niche = + Niche::from_scalar(dl, offset, niche_scalar.clone()); + + niche_filling_layout = Some(Layout { + variants: Variants::Multiple { + tag: niche_scalar, + tag_encoding: TagEncoding::Niche { + dataful_variant: i, + niche_variants, + niche_start, + }, + tag_field: 0, + variants: st, + }, + fields: FieldsShape::Arbitrary { + offsets: vec![offset], + memory_index: vec![0], + }, + abi, + largest_niche, + size, + align, + }); + } + } + } + + let (mut min, mut max) = (i128::MAX, i128::MIN); + let discr_type = def.repr.discr_type(); + let bits = Integer::from_attr(self, discr_type).size().bits(); + for (i, discr) in def.discriminants(tcx) { + if variants[i].iter().any(|f| f.abi.is_uninhabited()) { + continue; + } + let mut x = discr.val as i128; + if discr_type.is_signed() { + // sign extend the raw representation to be an i128 + x = (x << (128 - bits)) >> (128 - bits); + } + if x < min { + min = x; + } + if x > max { + max = x; + } + } + // We might have no inhabited variants, so pretend there's at least one. + if (min, max) == (i128::MAX, i128::MIN) { + min = 0; + max = 0; + } + assert!(min <= max, "discriminant range is {}...{}", min, max); + let (min_ity, signed) = Integer::repr_discr(tcx, ty, &def.repr, min, max); + + let mut align = dl.aggregate_align; + let mut size = Size::ZERO; + + // We're interested in the smallest alignment, so start large. + let mut start_align = Align::from_bytes(256).unwrap(); + assert_eq!(Integer::for_align(dl, start_align), None); + + // repr(C) on an enum tells us to make a (tag, union) layout, + // so we need to grow the prefix alignment to be at least + // the alignment of the union. (This value is used both for + // determining the alignment of the overall enum, and the + // determining the alignment of the payload after the tag.) + let mut prefix_align = min_ity.align(dl).abi; + if def.repr.c() { + for fields in &variants { + for field in fields { + prefix_align = prefix_align.max(field.align.abi); + } + } + } + + // Create the set of structs that represent each variant. + let mut layout_variants = variants + .iter_enumerated() + .map(|(i, field_layouts)| { + let mut st = self.univariant_uninterned( + ty, + &field_layouts, + &def.repr, + StructKind::Prefixed(min_ity.size(), prefix_align), + )?; + st.variants = Variants::Single { index: i }; + // Find the first field we can't move later + // to make room for a larger discriminant. + for field in + st.fields.index_by_increasing_offset().map(|j| field_layouts[j]) + { + if !field.is_zst() || field.align.abi.bytes() != 1 { + start_align = start_align.min(field.align.abi); + break; + } + } + size = cmp::max(size, st.size); + align = align.max(st.align); + Ok(st) + }) + .collect::<Result<IndexVec<VariantIdx, _>, _>>()?; + + // Align the maximum variant size to the largest alignment. + size = size.align_to(align.abi); + + if size.bytes() >= dl.obj_size_bound() { + return Err(LayoutError::SizeOverflow(ty)); + } + + let typeck_ity = Integer::from_attr(dl, def.repr.discr_type()); + if typeck_ity < min_ity { + // It is a bug if Layout decided on a greater discriminant size than typeck for + // some reason at this point (based on values discriminant can take on). Mostly + // because this discriminant will be loaded, and then stored into variable of + // type calculated by typeck. Consider such case (a bug): typeck decided on + // byte-sized discriminant, but layout thinks we need a 16-bit to store all + // discriminant values. That would be a bug, because then, in codegen, in order + // to store this 16-bit discriminant into 8-bit sized temporary some of the + // space necessary to represent would have to be discarded (or layout is wrong + // on thinking it needs 16 bits) + bug!( + "layout decided on a larger discriminant type ({:?}) than typeck ({:?})", + min_ity, + typeck_ity + ); + // However, it is fine to make discr type however large (as an optimisation) + // after this point – we’ll just truncate the value we load in codegen. + } + + // Check to see if we should use a different type for the + // discriminant. We can safely use a type with the same size + // as the alignment of the first field of each variant. + // We increase the size of the discriminant to avoid LLVM copying + // padding when it doesn't need to. This normally causes unaligned + // load/stores and excessive memcpy/memset operations. By using a + // bigger integer size, LLVM can be sure about its contents and + // won't be so conservative. + + // Use the initial field alignment + let mut ity = if def.repr.c() || def.repr.int.is_some() { + min_ity + } else { + Integer::for_align(dl, start_align).unwrap_or(min_ity) + }; + + // If the alignment is not larger than the chosen discriminant size, + // don't use the alignment as the final size. + if ity <= min_ity { + ity = min_ity; + } else { + // Patch up the variants' first few fields. + let old_ity_size = min_ity.size(); + let new_ity_size = ity.size(); + for variant in &mut layout_variants { + match variant.fields { + FieldsShape::Arbitrary { ref mut offsets, .. } => { + for i in offsets { + if *i <= old_ity_size { + assert_eq!(*i, old_ity_size); + *i = new_ity_size; + } + } + // We might be making the struct larger. + if variant.size <= old_ity_size { + variant.size = new_ity_size; + } + } + _ => bug!(), + } + } + } + + let tag_mask = !0u128 >> (128 - ity.size().bits()); + let tag = Scalar { + value: Int(ity, signed), + valid_range: (min as u128 & tag_mask)..=(max as u128 & tag_mask), + }; + let mut abi = Abi::Aggregate { sized: true }; + if tag.value.size(dl) == size { + abi = Abi::Scalar(tag.clone()); + } else { + // Try to use a ScalarPair for all tagged enums. + let mut common_prim = None; + for (field_layouts, layout_variant) in variants.iter().zip(&layout_variants) { + let offsets = match layout_variant.fields { + FieldsShape::Arbitrary { ref offsets, .. } => offsets, + _ => bug!(), + }; + let mut fields = + field_layouts.iter().zip(offsets).filter(|p| !p.0.is_zst()); + let (field, offset) = match (fields.next(), fields.next()) { + (None, None) => continue, + (Some(pair), None) => pair, + _ => { + common_prim = None; + break; + } + }; + let prim = match field.abi { + Abi::Scalar(ref scalar) => scalar.value, + _ => { + common_prim = None; + break; + } + }; + if let Some(pair) = common_prim { + // This is pretty conservative. We could go fancier + // by conflating things like i32 and u32, or even + // realising that (u8, u8) could just cohabit with + // u16 or even u32. + if pair != (prim, offset) { + common_prim = None; + break; + } + } else { + common_prim = Some((prim, offset)); + } + } + if let Some((prim, offset)) = common_prim { + let pair = self.scalar_pair(tag.clone(), scalar_unit(prim)); + let pair_offsets = match pair.fields { + FieldsShape::Arbitrary { ref offsets, ref memory_index } => { + assert_eq!(memory_index, &[0, 1]); + offsets + } + _ => bug!(), + }; + if pair_offsets[0] == Size::ZERO + && pair_offsets[1] == *offset + && align == pair.align + && size == pair.size + { + // We can use `ScalarPair` only when it matches our + // already computed layout (including `#[repr(C)]`). + abi = pair.abi; + } + } + } + + if layout_variants.iter().all(|v| v.abi.is_uninhabited()) { + abi = Abi::Uninhabited; + } + + let largest_niche = Niche::from_scalar(dl, Size::ZERO, tag.clone()); + + let tagged_layout = Layout { + variants: Variants::Multiple { + tag, + tag_encoding: TagEncoding::Direct, + tag_field: 0, + variants: layout_variants, + }, + fields: FieldsShape::Arbitrary { + offsets: vec![Size::ZERO], + memory_index: vec![0], + }, + largest_niche, + abi, + align, + size, + }; + + let best_layout = match (tagged_layout, niche_filling_layout) { + (tagged_layout, Some(niche_filling_layout)) => { + // Pick the smaller layout; otherwise, + // pick the layout with the larger niche; otherwise, + // pick tagged as it has simpler codegen. + cmp::min_by_key(tagged_layout, niche_filling_layout, |layout| { + let niche_size = + layout.largest_niche.as_ref().map_or(0, |n| n.available(dl)); + (layout.size, cmp::Reverse(niche_size)) + }) + } + (tagged_layout, None) => tagged_layout, + }; + + tcx.intern_layout(best_layout) + } + + // Types with no meaningful known layout. + ty::Projection(_) | ty::Opaque(..) => { + let normalized = tcx.normalize_erasing_regions(param_env, ty); + if ty == normalized { + return Err(LayoutError::Unknown(ty)); + } + tcx.layout_raw(param_env.and(normalized))? + } + + ty::Bound(..) | ty::Placeholder(..) | ty::GeneratorWitness(..) | ty::Infer(_) => { + bug!("Layout::compute: unexpected type `{}`", ty) + } + + ty::Param(_) | ty::Error(_) => { + return Err(LayoutError::Unknown(ty)); + } + }) + } +} + +/// Overlap eligibility and variant assignment for each GeneratorSavedLocal. +#[derive(Clone, Debug, PartialEq)] +enum SavedLocalEligibility { + Unassigned, + Assigned(VariantIdx), + // FIXME: Use newtype_index so we aren't wasting bytes + Ineligible(Option<u32>), +} + +// When laying out generators, we divide our saved local fields into two +// categories: overlap-eligible and overlap-ineligible. +// +// Those fields which are ineligible for overlap go in a "prefix" at the +// beginning of the layout, and always have space reserved for them. +// +// Overlap-eligible fields are only assigned to one variant, so we lay +// those fields out for each variant and put them right after the +// prefix. +// +// Finally, in the layout details, we point to the fields from the +// variants they are assigned to. It is possible for some fields to be +// included in multiple variants. No field ever "moves around" in the +// layout; its offset is always the same. +// +// Also included in the layout are the upvars and the discriminant. +// These are included as fields on the "outer" layout; they are not part +// of any variant. +impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> { + /// Compute the eligibility and assignment of each local. + fn generator_saved_local_eligibility( + &self, + info: &GeneratorLayout<'tcx>, + ) -> (BitSet<GeneratorSavedLocal>, IndexVec<GeneratorSavedLocal, SavedLocalEligibility>) { + use SavedLocalEligibility::*; + + let mut assignments: IndexVec<GeneratorSavedLocal, SavedLocalEligibility> = + IndexVec::from_elem_n(Unassigned, info.field_tys.len()); + + // The saved locals not eligible for overlap. These will get + // "promoted" to the prefix of our generator. + let mut ineligible_locals = BitSet::new_empty(info.field_tys.len()); + + // Figure out which of our saved locals are fields in only + // one variant. The rest are deemed ineligible for overlap. + for (variant_index, fields) in info.variant_fields.iter_enumerated() { + for local in fields { + match assignments[*local] { + Unassigned => { + assignments[*local] = Assigned(variant_index); + } + Assigned(idx) => { + // We've already seen this local at another suspension + // point, so it is no longer a candidate. + trace!( + "removing local {:?} in >1 variant ({:?}, {:?})", + local, + variant_index, + idx + ); + ineligible_locals.insert(*local); + assignments[*local] = Ineligible(None); + } + Ineligible(_) => {} + } + } + } + + // Next, check every pair of eligible locals to see if they + // conflict. + for local_a in info.storage_conflicts.rows() { + let conflicts_a = info.storage_conflicts.count(local_a); + if ineligible_locals.contains(local_a) { + continue; + } + + for local_b in info.storage_conflicts.iter(local_a) { + // local_a and local_b are storage live at the same time, therefore they + // cannot overlap in the generator layout. The only way to guarantee + // this is if they are in the same variant, or one is ineligible + // (which means it is stored in every variant). + if ineligible_locals.contains(local_b) + || assignments[local_a] == assignments[local_b] + { + continue; + } + + // If they conflict, we will choose one to make ineligible. + // This is not always optimal; it's just a greedy heuristic that + // seems to produce good results most of the time. + let conflicts_b = info.storage_conflicts.count(local_b); + let (remove, other) = + if conflicts_a > conflicts_b { (local_a, local_b) } else { (local_b, local_a) }; + ineligible_locals.insert(remove); + assignments[remove] = Ineligible(None); + trace!("removing local {:?} due to conflict with {:?}", remove, other); + } + } + + // Count the number of variants in use. If only one of them, then it is + // impossible to overlap any locals in our layout. In this case it's + // always better to make the remaining locals ineligible, so we can + // lay them out with the other locals in the prefix and eliminate + // unnecessary padding bytes. + { + let mut used_variants = BitSet::new_empty(info.variant_fields.len()); + for assignment in &assignments { + if let Assigned(idx) = assignment { + used_variants.insert(*idx); + } + } + if used_variants.count() < 2 { + for assignment in assignments.iter_mut() { + *assignment = Ineligible(None); + } + ineligible_locals.insert_all(); + } + } + + // Write down the order of our locals that will be promoted to the prefix. + { + for (idx, local) in ineligible_locals.iter().enumerate() { + assignments[local] = Ineligible(Some(idx as u32)); + } + } + debug!("generator saved local assignments: {:?}", assignments); + + (ineligible_locals, assignments) + } + + /// Compute the full generator layout. + fn generator_layout( + &self, + ty: Ty<'tcx>, + def_id: hir::def_id::DefId, + substs: SubstsRef<'tcx>, + ) -> Result<&'tcx Layout, LayoutError<'tcx>> { + use SavedLocalEligibility::*; + let tcx = self.tcx; + + let subst_field = |ty: Ty<'tcx>| ty.subst(tcx, substs); + + let info = tcx.generator_layout(def_id); + let (ineligible_locals, assignments) = self.generator_saved_local_eligibility(&info); + + // Build a prefix layout, including "promoting" all ineligible + // locals as part of the prefix. We compute the layout of all of + // these fields at once to get optimal packing. + let tag_index = substs.as_generator().prefix_tys().count(); + + // `info.variant_fields` already accounts for the reserved variants, so no need to add them. + let max_discr = (info.variant_fields.len() - 1) as u128; + let discr_int = Integer::fit_unsigned(max_discr); + let discr_int_ty = discr_int.to_ty(tcx, false); + let tag = Scalar { value: Primitive::Int(discr_int, false), valid_range: 0..=max_discr }; + let tag_layout = self.tcx.intern_layout(Layout::scalar(self, tag.clone())); + let tag_layout = TyAndLayout { ty: discr_int_ty, layout: tag_layout }; + + let promoted_layouts = ineligible_locals + .iter() + .map(|local| subst_field(info.field_tys[local])) + .map(|ty| tcx.mk_maybe_uninit(ty)) + .map(|ty| self.layout_of(ty)); + let prefix_layouts = substs + .as_generator() + .prefix_tys() + .map(|ty| self.layout_of(ty)) + .chain(iter::once(Ok(tag_layout))) + .chain(promoted_layouts) + .collect::<Result<Vec<_>, _>>()?; + let prefix = self.univariant_uninterned( + ty, + &prefix_layouts, + &ReprOptions::default(), + StructKind::AlwaysSized, + )?; + + let (prefix_size, prefix_align) = (prefix.size, prefix.align); + + // Split the prefix layout into the "outer" fields (upvars and + // discriminant) and the "promoted" fields. Promoted fields will + // get included in each variant that requested them in + // GeneratorLayout. + debug!("prefix = {:#?}", prefix); + let (outer_fields, promoted_offsets, promoted_memory_index) = match prefix.fields { + FieldsShape::Arbitrary { mut offsets, memory_index } => { + let mut inverse_memory_index = invert_mapping(&memory_index); + + // "a" (`0..b_start`) and "b" (`b_start..`) correspond to + // "outer" and "promoted" fields respectively. + let b_start = (tag_index + 1) as u32; + let offsets_b = offsets.split_off(b_start as usize); + let offsets_a = offsets; + + // Disentangle the "a" and "b" components of `inverse_memory_index` + // by preserving the order but keeping only one disjoint "half" each. + // FIXME(eddyb) build a better abstraction for permutations, if possible. + let inverse_memory_index_b: Vec<_> = + inverse_memory_index.iter().filter_map(|&i| i.checked_sub(b_start)).collect(); + inverse_memory_index.retain(|&i| i < b_start); + let inverse_memory_index_a = inverse_memory_index; + + // Since `inverse_memory_index_{a,b}` each only refer to their + // respective fields, they can be safely inverted + let memory_index_a = invert_mapping(&inverse_memory_index_a); + let memory_index_b = invert_mapping(&inverse_memory_index_b); + + let outer_fields = + FieldsShape::Arbitrary { offsets: offsets_a, memory_index: memory_index_a }; + (outer_fields, offsets_b, memory_index_b) + } + _ => bug!(), + }; + + let mut size = prefix.size; + let mut align = prefix.align; + let variants = info + .variant_fields + .iter_enumerated() + .map(|(index, variant_fields)| { + // Only include overlap-eligible fields when we compute our variant layout. + let variant_only_tys = variant_fields + .iter() + .filter(|local| match assignments[**local] { + Unassigned => bug!(), + Assigned(v) if v == index => true, + Assigned(_) => bug!("assignment does not match variant"), + Ineligible(_) => false, + }) + .map(|local| subst_field(info.field_tys[*local])); + + let mut variant = self.univariant_uninterned( + ty, + &variant_only_tys + .map(|ty| self.layout_of(ty)) + .collect::<Result<Vec<_>, _>>()?, + &ReprOptions::default(), + StructKind::Prefixed(prefix_size, prefix_align.abi), + )?; + variant.variants = Variants::Single { index }; + + let (offsets, memory_index) = match variant.fields { + FieldsShape::Arbitrary { offsets, memory_index } => (offsets, memory_index), + _ => bug!(), + }; + + // Now, stitch the promoted and variant-only fields back together in + // the order they are mentioned by our GeneratorLayout. + // Because we only use some subset (that can differ between variants) + // of the promoted fields, we can't just pick those elements of the + // `promoted_memory_index` (as we'd end up with gaps). + // So instead, we build an "inverse memory_index", as if all of the + // promoted fields were being used, but leave the elements not in the + // subset as `INVALID_FIELD_IDX`, which we can filter out later to + // obtain a valid (bijective) mapping. + const INVALID_FIELD_IDX: u32 = !0; + let mut combined_inverse_memory_index = + vec![INVALID_FIELD_IDX; promoted_memory_index.len() + memory_index.len()]; + let mut offsets_and_memory_index = offsets.into_iter().zip(memory_index); + let combined_offsets = variant_fields + .iter() + .enumerate() + .map(|(i, local)| { + let (offset, memory_index) = match assignments[*local] { + Unassigned => bug!(), + Assigned(_) => { + let (offset, memory_index) = + offsets_and_memory_index.next().unwrap(); + (offset, promoted_memory_index.len() as u32 + memory_index) + } + Ineligible(field_idx) => { + let field_idx = field_idx.unwrap() as usize; + (promoted_offsets[field_idx], promoted_memory_index[field_idx]) + } + }; + combined_inverse_memory_index[memory_index as usize] = i as u32; + offset + }) + .collect(); + + // Remove the unused slots and invert the mapping to obtain the + // combined `memory_index` (also see previous comment). + combined_inverse_memory_index.retain(|&i| i != INVALID_FIELD_IDX); + let combined_memory_index = invert_mapping(&combined_inverse_memory_index); + + variant.fields = FieldsShape::Arbitrary { + offsets: combined_offsets, + memory_index: combined_memory_index, + }; + + size = size.max(variant.size); + align = align.max(variant.align); + Ok(variant) + }) + .collect::<Result<IndexVec<VariantIdx, _>, _>>()?; + + size = size.align_to(align.abi); + + let abi = if prefix.abi.is_uninhabited() || variants.iter().all(|v| v.abi.is_uninhabited()) + { + Abi::Uninhabited + } else { + Abi::Aggregate { sized: true } + }; + + let layout = tcx.intern_layout(Layout { + variants: Variants::Multiple { + tag: tag, + tag_encoding: TagEncoding::Direct, + tag_field: tag_index, + variants, + }, + fields: outer_fields, + abi, + largest_niche: prefix.largest_niche, + size, + align, + }); + debug!("generator layout ({:?}): {:#?}", ty, layout); + Ok(layout) + } + + /// This is invoked by the `layout_raw` query to record the final + /// layout of each type. + #[inline(always)] + fn record_layout_for_printing(&self, layout: TyAndLayout<'tcx>) { + // If we are running with `-Zprint-type-sizes`, maybe record layouts + // for dumping later. + if self.tcx.sess.opts.debugging_opts.print_type_sizes { + self.record_layout_for_printing_outlined(layout) + } + } + + fn record_layout_for_printing_outlined(&self, layout: TyAndLayout<'tcx>) { + // Ignore layouts that are done with non-empty environments or + // non-monomorphic layouts, as the user only wants to see the stuff + // resulting from the final codegen session. + if layout.ty.has_param_types_or_consts() || !self.param_env.caller_bounds().is_empty() { + return; + } + + // (delay format until we actually need it) + let record = |kind, packed, opt_discr_size, variants| { + let type_desc = format!("{:?}", layout.ty); + self.tcx.sess.code_stats.record_type_size( + kind, + type_desc, + layout.align.abi, + layout.size, + packed, + opt_discr_size, + variants, + ); + }; + + let adt_def = match layout.ty.kind { + ty::Adt(ref adt_def, _) => { + debug!("print-type-size t: `{:?}` process adt", layout.ty); + adt_def + } + + ty::Closure(..) => { + debug!("print-type-size t: `{:?}` record closure", layout.ty); + record(DataTypeKind::Closure, false, None, vec![]); + return; + } + + _ => { + debug!("print-type-size t: `{:?}` skip non-nominal", layout.ty); + return; + } + }; + + let adt_kind = adt_def.adt_kind(); + let adt_packed = adt_def.repr.pack.is_some(); + + let build_variant_info = |n: Option<Ident>, flds: &[Symbol], layout: TyAndLayout<'tcx>| { + let mut min_size = Size::ZERO; + let field_info: Vec<_> = flds + .iter() + .enumerate() + .map(|(i, &name)| match layout.field(self, i) { + Err(err) => { + bug!("no layout found for field {}: `{:?}`", name, err); + } + Ok(field_layout) => { + let offset = layout.fields.offset(i); + let field_end = offset + field_layout.size; + if min_size < field_end { + min_size = field_end; + } + FieldInfo { + name: name.to_string(), + offset: offset.bytes(), + size: field_layout.size.bytes(), + align: field_layout.align.abi.bytes(), + } + } + }) + .collect(); + + VariantInfo { + name: n.map(|n| n.to_string()), + kind: if layout.is_unsized() { SizeKind::Min } else { SizeKind::Exact }, + align: layout.align.abi.bytes(), + size: if min_size.bytes() == 0 { layout.size.bytes() } else { min_size.bytes() }, + fields: field_info, + } + }; + + match layout.variants { + Variants::Single { index } => { + debug!("print-type-size `{:#?}` variant {}", layout, adt_def.variants[index].ident); + if !adt_def.variants.is_empty() { + let variant_def = &adt_def.variants[index]; + let fields: Vec<_> = variant_def.fields.iter().map(|f| f.ident.name).collect(); + record( + adt_kind.into(), + adt_packed, + None, + vec![build_variant_info(Some(variant_def.ident), &fields, layout)], + ); + } else { + // (This case arises for *empty* enums; so give it + // zero variants.) + record(adt_kind.into(), adt_packed, None, vec![]); + } + } + + Variants::Multiple { ref tag, ref tag_encoding, .. } => { + debug!( + "print-type-size `{:#?}` adt general variants def {}", + layout.ty, + adt_def.variants.len() + ); + let variant_infos: Vec<_> = adt_def + .variants + .iter_enumerated() + .map(|(i, variant_def)| { + let fields: Vec<_> = + variant_def.fields.iter().map(|f| f.ident.name).collect(); + build_variant_info( + Some(variant_def.ident), + &fields, + layout.for_variant(self, i), + ) + }) + .collect(); + record( + adt_kind.into(), + adt_packed, + match tag_encoding { + TagEncoding::Direct => Some(tag.value.size(self)), + _ => None, + }, + variant_infos, + ); + } + } + } +} + +/// Type size "skeleton", i.e., the only information determining a type's size. +/// While this is conservative, (aside from constant sizes, only pointers, +/// newtypes thereof and null pointer optimized enums are allowed), it is +/// enough to statically check common use cases of transmute. +#[derive(Copy, Clone, Debug)] +pub enum SizeSkeleton<'tcx> { + /// Any statically computable Layout. + Known(Size), + + /// A potentially-fat pointer. + Pointer { + /// If true, this pointer is never null. + non_zero: bool, + /// The type which determines the unsized metadata, if any, + /// of this pointer. Either a type parameter or a projection + /// depending on one, with regions erased. + tail: Ty<'tcx>, + }, +} + +impl<'tcx> SizeSkeleton<'tcx> { + pub fn compute( + ty: Ty<'tcx>, + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> Result<SizeSkeleton<'tcx>, LayoutError<'tcx>> { + debug_assert!(!ty.has_infer_types_or_consts()); + + // First try computing a static layout. + let err = match tcx.layout_of(param_env.and(ty)) { + Ok(layout) => { + return Ok(SizeSkeleton::Known(layout.size)); + } + Err(err) => err, + }; + + match ty.kind { + ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => { + let non_zero = !ty.is_unsafe_ptr(); + let tail = tcx.struct_tail_erasing_lifetimes(pointee, param_env); + match tail.kind { + ty::Param(_) | ty::Projection(_) => { + debug_assert!(tail.has_param_types_or_consts()); + Ok(SizeSkeleton::Pointer { non_zero, tail: tcx.erase_regions(&tail) }) + } + _ => bug!( + "SizeSkeleton::compute({}): layout errored ({}), yet \ + tail `{}` is not a type parameter or a projection", + ty, + err, + tail + ), + } + } + + ty::Adt(def, substs) => { + // Only newtypes and enums w/ nullable pointer optimization. + if def.is_union() || def.variants.is_empty() || def.variants.len() > 2 { + return Err(err); + } + + // Get a zero-sized variant or a pointer newtype. + let zero_or_ptr_variant = |i| { + let i = VariantIdx::new(i); + let fields = def.variants[i] + .fields + .iter() + .map(|field| SizeSkeleton::compute(field.ty(tcx, substs), tcx, param_env)); + let mut ptr = None; + for field in fields { + let field = field?; + match field { + SizeSkeleton::Known(size) => { + if size.bytes() > 0 { + return Err(err); + } + } + SizeSkeleton::Pointer { .. } => { + if ptr.is_some() { + return Err(err); + } + ptr = Some(field); + } + } + } + Ok(ptr) + }; + + let v0 = zero_or_ptr_variant(0)?; + // Newtype. + if def.variants.len() == 1 { + if let Some(SizeSkeleton::Pointer { non_zero, tail }) = v0 { + return Ok(SizeSkeleton::Pointer { + non_zero: non_zero + || match tcx.layout_scalar_valid_range(def.did) { + (Bound::Included(start), Bound::Unbounded) => start > 0, + (Bound::Included(start), Bound::Included(end)) => { + 0 < start && start < end + } + _ => false, + }, + tail, + }); + } else { + return Err(err); + } + } + + let v1 = zero_or_ptr_variant(1)?; + // Nullable pointer enum optimization. + match (v0, v1) { + (Some(SizeSkeleton::Pointer { non_zero: true, tail }), None) + | (None, Some(SizeSkeleton::Pointer { non_zero: true, tail })) => { + Ok(SizeSkeleton::Pointer { non_zero: false, tail }) + } + _ => Err(err), + } + } + + ty::Projection(_) | ty::Opaque(..) => { + let normalized = tcx.normalize_erasing_regions(param_env, ty); + if ty == normalized { + Err(err) + } else { + SizeSkeleton::compute(normalized, tcx, param_env) + } + } + + _ => Err(err), + } + } + + pub fn same_size(self, other: SizeSkeleton<'_>) -> bool { + match (self, other) { + (SizeSkeleton::Known(a), SizeSkeleton::Known(b)) => a == b, + (SizeSkeleton::Pointer { tail: a, .. }, SizeSkeleton::Pointer { tail: b, .. }) => { + a == b + } + _ => false, + } + } +} + +pub trait HasTyCtxt<'tcx>: HasDataLayout { + fn tcx(&self) -> TyCtxt<'tcx>; +} + +pub trait HasParamEnv<'tcx> { + fn param_env(&self) -> ty::ParamEnv<'tcx>; +} + +impl<'tcx> HasDataLayout for TyCtxt<'tcx> { + fn data_layout(&self) -> &TargetDataLayout { + &self.data_layout + } +} + +impl<'tcx> HasTyCtxt<'tcx> for TyCtxt<'tcx> { + fn tcx(&self) -> TyCtxt<'tcx> { + *self + } +} + +impl<'tcx, C> HasParamEnv<'tcx> for LayoutCx<'tcx, C> { + fn param_env(&self) -> ty::ParamEnv<'tcx> { + self.param_env + } +} + +impl<'tcx, T: HasDataLayout> HasDataLayout for LayoutCx<'tcx, T> { + fn data_layout(&self) -> &TargetDataLayout { + self.tcx.data_layout() + } +} + +impl<'tcx, T: HasTyCtxt<'tcx>> HasTyCtxt<'tcx> for LayoutCx<'tcx, T> { + fn tcx(&self) -> TyCtxt<'tcx> { + self.tcx.tcx() + } +} + +pub type TyAndLayout<'tcx> = ::rustc_target::abi::TyAndLayout<'tcx, Ty<'tcx>>; + +impl<'tcx> LayoutOf for LayoutCx<'tcx, TyCtxt<'tcx>> { + type Ty = Ty<'tcx>; + type TyAndLayout = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>; + + /// Computes the layout of a type. Note that this implicitly + /// executes in "reveal all" mode. + fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout { + let param_env = self.param_env.with_reveal_all_normalized(self.tcx); + let ty = self.tcx.normalize_erasing_regions(param_env, ty); + let layout = self.tcx.layout_raw(param_env.and(ty))?; + let layout = TyAndLayout { ty, layout }; + + // N.B., this recording is normally disabled; when enabled, it + // can however trigger recursive invocations of `layout_of`. + // Therefore, we execute it *after* the main query has + // completed, to avoid problems around recursive structures + // and the like. (Admittedly, I wasn't able to reproduce a problem + // here, but it seems like the right thing to do. -nmatsakis) + self.record_layout_for_printing(layout); + + Ok(layout) + } +} + +impl LayoutOf for LayoutCx<'tcx, ty::query::TyCtxtAt<'tcx>> { + type Ty = Ty<'tcx>; + type TyAndLayout = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>; + + /// Computes the layout of a type. Note that this implicitly + /// executes in "reveal all" mode. + fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout { + let param_env = self.param_env.with_reveal_all_normalized(*self.tcx); + let ty = self.tcx.normalize_erasing_regions(param_env, ty); + let layout = self.tcx.layout_raw(param_env.and(ty))?; + let layout = TyAndLayout { ty, layout }; + + // N.B., this recording is normally disabled; when enabled, it + // can however trigger recursive invocations of `layout_of`. + // Therefore, we execute it *after* the main query has + // completed, to avoid problems around recursive structures + // and the like. (Admittedly, I wasn't able to reproduce a problem + // here, but it seems like the right thing to do. -nmatsakis) + let cx = LayoutCx { tcx: *self.tcx, param_env: self.param_env }; + cx.record_layout_for_printing(layout); + + Ok(layout) + } +} + +// Helper (inherent) `layout_of` methods to avoid pushing `LayoutCx` to users. +impl TyCtxt<'tcx> { + /// Computes the layout of a type. Note that this implicitly + /// executes in "reveal all" mode. + #[inline] + pub fn layout_of( + self, + param_env_and_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, + ) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> { + let cx = LayoutCx { tcx: self, param_env: param_env_and_ty.param_env }; + cx.layout_of(param_env_and_ty.value) + } +} + +impl ty::query::TyCtxtAt<'tcx> { + /// Computes the layout of a type. Note that this implicitly + /// executes in "reveal all" mode. + #[inline] + pub fn layout_of( + self, + param_env_and_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, + ) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> { + let cx = LayoutCx { tcx: self.at(self.span), param_env: param_env_and_ty.param_env }; + cx.layout_of(param_env_and_ty.value) + } +} + +impl<'tcx, C> TyAndLayoutMethods<'tcx, C> for Ty<'tcx> +where + C: LayoutOf<Ty = Ty<'tcx>, TyAndLayout: MaybeResult<TyAndLayout<'tcx>>> + + HasTyCtxt<'tcx> + + HasParamEnv<'tcx>, +{ + fn for_variant( + this: TyAndLayout<'tcx>, + cx: &C, + variant_index: VariantIdx, + ) -> TyAndLayout<'tcx> { + let layout = match this.variants { + Variants::Single { index } + // If all variants but one are uninhabited, the variant layout is the enum layout. + if index == variant_index && + // Don't confuse variants of uninhabited enums with the enum itself. + // For more details see https://github.com/rust-lang/rust/issues/69763. + this.fields != FieldsShape::Primitive => + { + this.layout + } + + Variants::Single { index } => { + // Deny calling for_variant more than once for non-Single enums. + if let Ok(original_layout) = cx.layout_of(this.ty).to_result() { + assert_eq!(original_layout.variants, Variants::Single { index }); + } + + let fields = match this.ty.kind { + ty::Adt(def, _) if def.variants.is_empty() => + bug!("for_variant called on zero-variant enum"), + ty::Adt(def, _) => def.variants[variant_index].fields.len(), + _ => bug!(), + }; + let tcx = cx.tcx(); + tcx.intern_layout(Layout { + variants: Variants::Single { index: variant_index }, + fields: match NonZeroUsize::new(fields) { + Some(fields) => FieldsShape::Union(fields), + None => FieldsShape::Arbitrary { offsets: vec![], memory_index: vec![] }, + }, + abi: Abi::Uninhabited, + largest_niche: None, + align: tcx.data_layout.i8_align, + size: Size::ZERO, + }) + } + + Variants::Multiple { ref variants, .. } => &variants[variant_index], + }; + + assert_eq!(layout.variants, Variants::Single { index: variant_index }); + + TyAndLayout { ty: this.ty, layout } + } + + fn field(this: TyAndLayout<'tcx>, cx: &C, i: usize) -> C::TyAndLayout { + let tcx = cx.tcx(); + let tag_layout = |tag: &Scalar| -> C::TyAndLayout { + let layout = Layout::scalar(cx, tag.clone()); + MaybeResult::from(Ok(TyAndLayout { + layout: tcx.intern_layout(layout), + ty: tag.value.to_ty(tcx), + })) + }; + + cx.layout_of(match this.ty.kind { + ty::Bool + | ty::Char + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::FnPtr(_) + | ty::Never + | ty::FnDef(..) + | ty::GeneratorWitness(..) + | ty::Foreign(..) + | ty::Dynamic(..) => bug!("TyAndLayout::field_type({:?}): not applicable", this), + + // Potentially-fat pointers. + ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => { + assert!(i < this.fields.count()); + + // Reuse the fat `*T` type as its own thin pointer data field. + // This provides information about, e.g., DST struct pointees + // (which may have no non-DST form), and will work as long + // as the `Abi` or `FieldsShape` is checked by users. + if i == 0 { + let nil = tcx.mk_unit(); + let ptr_ty = if this.ty.is_unsafe_ptr() { + tcx.mk_mut_ptr(nil) + } else { + tcx.mk_mut_ref(tcx.lifetimes.re_static, nil) + }; + return MaybeResult::from(cx.layout_of(ptr_ty).to_result().map( + |mut ptr_layout| { + ptr_layout.ty = this.ty; + ptr_layout + }, + )); + } + + match tcx.struct_tail_erasing_lifetimes(pointee, cx.param_env()).kind { + ty::Slice(_) | ty::Str => tcx.types.usize, + ty::Dynamic(_, _) => { + tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.usize, 3)) + /* FIXME: use actual fn pointers + Warning: naively computing the number of entries in the + vtable by counting the methods on the trait + methods on + all parent traits does not work, because some methods can + be not object safe and thus excluded from the vtable. + Increase this counter if you tried to implement this but + failed to do it without duplicating a lot of code from + other places in the compiler: 2 + tcx.mk_tup(&[ + tcx.mk_array(tcx.types.usize, 3), + tcx.mk_array(Option<fn()>), + ]) + */ + } + _ => bug!("TyAndLayout::field_type({:?}): not applicable", this), + } + } + + // Arrays and slices. + ty::Array(element, _) | ty::Slice(element) => element, + ty::Str => tcx.types.u8, + + // Tuples, generators and closures. + ty::Closure(_, ref substs) => substs.as_closure().upvar_tys().nth(i).unwrap(), + + ty::Generator(def_id, ref substs, _) => match this.variants { + Variants::Single { index } => substs + .as_generator() + .state_tys(def_id, tcx) + .nth(index.as_usize()) + .unwrap() + .nth(i) + .unwrap(), + Variants::Multiple { ref tag, tag_field, .. } => { + if i == tag_field { + return tag_layout(tag); + } + substs.as_generator().prefix_tys().nth(i).unwrap() + } + }, + + ty::Tuple(tys) => tys[i].expect_ty(), + + // SIMD vector types. + ty::Adt(def, ..) if def.repr.simd() => this.ty.simd_type(tcx), + + // ADTs. + ty::Adt(def, substs) => { + match this.variants { + Variants::Single { index } => def.variants[index].fields[i].ty(tcx, substs), + + // Discriminant field for enums (where applicable). + Variants::Multiple { ref tag, .. } => { + assert_eq!(i, 0); + return tag_layout(tag); + } + } + } + + ty::Projection(_) + | ty::Bound(..) + | ty::Placeholder(..) + | ty::Opaque(..) + | ty::Param(_) + | ty::Infer(_) + | ty::Error(_) => bug!("TyAndLayout::field_type: unexpected type `{}`", this.ty), + }) + } + + fn pointee_info_at(this: TyAndLayout<'tcx>, cx: &C, offset: Size) -> Option<PointeeInfo> { + let addr_space_of_ty = |ty: Ty<'tcx>| { + if ty.is_fn() { cx.data_layout().instruction_address_space } else { AddressSpace::DATA } + }; + + let pointee_info = match this.ty.kind { + ty::RawPtr(mt) if offset.bytes() == 0 => { + cx.layout_of(mt.ty).to_result().ok().map(|layout| PointeeInfo { + size: layout.size, + align: layout.align.abi, + safe: None, + address_space: addr_space_of_ty(mt.ty), + }) + } + ty::FnPtr(fn_sig) if offset.bytes() == 0 => { + cx.layout_of(cx.tcx().mk_fn_ptr(fn_sig)).to_result().ok().map(|layout| { + PointeeInfo { + size: layout.size, + align: layout.align.abi, + safe: None, + address_space: cx.data_layout().instruction_address_space, + } + }) + } + ty::Ref(_, ty, mt) if offset.bytes() == 0 => { + let address_space = addr_space_of_ty(ty); + let tcx = cx.tcx(); + let is_freeze = ty.is_freeze(tcx.at(DUMMY_SP), cx.param_env()); + let kind = match mt { + hir::Mutability::Not => { + if is_freeze { + PointerKind::Frozen + } else { + PointerKind::Shared + } + } + hir::Mutability::Mut => { + // Previously we would only emit noalias annotations for LLVM >= 6 or in + // panic=abort mode. That was deemed right, as prior versions had many bugs + // in conjunction with unwinding, but later versions didn’t seem to have + // said issues. See issue #31681. + // + // Alas, later on we encountered a case where noalias would generate wrong + // code altogether even with recent versions of LLVM in *safe* code with no + // unwinding involved. See #54462. + // + // For now, do not enable mutable_noalias by default at all, while the + // issue is being figured out. + if tcx.sess.opts.debugging_opts.mutable_noalias { + PointerKind::UniqueBorrowed + } else { + PointerKind::Shared + } + } + }; + + cx.layout_of(ty).to_result().ok().map(|layout| PointeeInfo { + size: layout.size, + align: layout.align.abi, + safe: Some(kind), + address_space, + }) + } + + _ => { + let mut data_variant = match this.variants { + // Within the discriminant field, only the niche itself is + // always initialized, so we only check for a pointer at its + // offset. + // + // If the niche is a pointer, it's either valid (according + // to its type), or null (which the niche field's scalar + // validity range encodes). This allows using + // `dereferenceable_or_null` for e.g., `Option<&T>`, and + // this will continue to work as long as we don't start + // using more niches than just null (e.g., the first page of + // the address space, or unaligned pointers). + Variants::Multiple { + tag_encoding: TagEncoding::Niche { dataful_variant, .. }, + tag_field, + .. + } if this.fields.offset(tag_field) == offset => { + Some(this.for_variant(cx, dataful_variant)) + } + _ => Some(this), + }; + + if let Some(variant) = data_variant { + // We're not interested in any unions. + if let FieldsShape::Union(_) = variant.fields { + data_variant = None; + } + } + + let mut result = None; + + if let Some(variant) = data_variant { + let ptr_end = offset + Pointer.size(cx); + for i in 0..variant.fields.count() { + let field_start = variant.fields.offset(i); + if field_start <= offset { + let field = variant.field(cx, i); + result = field.to_result().ok().and_then(|field| { + if ptr_end <= field_start + field.size { + // We found the right field, look inside it. + let field_info = + field.pointee_info_at(cx, offset - field_start); + field_info + } else { + None + } + }); + if result.is_some() { + break; + } + } + } + } + + // FIXME(eddyb) This should be for `ptr::Unique<T>`, not `Box<T>`. + if let Some(ref mut pointee) = result { + if let ty::Adt(def, _) = this.ty.kind { + if def.is_box() && offset.bytes() == 0 { + pointee.safe = Some(PointerKind::UniqueOwned); + } + } + } + + result + } + }; + + debug!( + "pointee_info_at (offset={:?}, type kind: {:?}) => {:?}", + offset, this.ty.kind, pointee_info + ); + + pointee_info + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for LayoutError<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + use crate::ty::layout::LayoutError::*; + mem::discriminant(self).hash_stable(hcx, hasher); + + match *self { + Unknown(t) | SizeOverflow(t) => t.hash_stable(hcx, hasher), + } + } +} + +impl<'tcx> ty::Instance<'tcx> { + // NOTE(eddyb) this is private to avoid using it from outside of + // `FnAbi::of_instance` - any other uses are either too high-level + // for `Instance` (e.g. typeck would use `Ty::fn_sig` instead), + // or should go through `FnAbi` instead, to avoid losing any + // adjustments `FnAbi::of_instance` might be performing. + fn fn_sig_for_fn_abi(&self, tcx: TyCtxt<'tcx>) -> ty::PolyFnSig<'tcx> { + // FIXME(davidtwco,eddyb): A `ParamEnv` should be passed through to this function. + let ty = self.ty(tcx, ty::ParamEnv::reveal_all()); + match ty.kind { + ty::FnDef(..) => { + // HACK(davidtwco,eddyb): This is a workaround for polymorphization considering + // parameters unused if they show up in the signature, but not in the `mir::Body` + // (i.e. due to being inside a projection that got normalized, see + // `src/test/ui/polymorphization/normalized_sig_types.rs`), and codegen not keeping + // track of a polymorphization `ParamEnv` to allow normalizing later. + let mut sig = match ty.kind { + ty::FnDef(def_id, substs) => tcx + .normalize_erasing_regions(tcx.param_env(def_id), tcx.fn_sig(def_id)) + .subst(tcx, substs), + _ => unreachable!(), + }; + + if let ty::InstanceDef::VtableShim(..) = self.def { + // Modify `fn(self, ...)` to `fn(self: *mut Self, ...)`. + sig = sig.map_bound(|mut sig| { + let mut inputs_and_output = sig.inputs_and_output.to_vec(); + inputs_and_output[0] = tcx.mk_mut_ptr(inputs_and_output[0]); + sig.inputs_and_output = tcx.intern_type_list(&inputs_and_output); + sig + }); + } + sig + } + ty::Closure(def_id, substs) => { + let sig = substs.as_closure().sig(); + + let env_ty = tcx.closure_env_ty(def_id, substs).unwrap(); + sig.map_bound(|sig| { + tcx.mk_fn_sig( + iter::once(env_ty.skip_binder()).chain(sig.inputs().iter().cloned()), + sig.output(), + sig.c_variadic, + sig.unsafety, + sig.abi, + ) + }) + } + ty::Generator(_, substs, _) => { + let sig = substs.as_generator().poly_sig(); + + let env_region = ty::ReLateBound(ty::INNERMOST, ty::BrEnv); + let env_ty = tcx.mk_mut_ref(tcx.mk_region(env_region), ty); + + let pin_did = tcx.require_lang_item(LangItem::Pin, None); + let pin_adt_ref = tcx.adt_def(pin_did); + let pin_substs = tcx.intern_substs(&[env_ty.into()]); + let env_ty = tcx.mk_adt(pin_adt_ref, pin_substs); + + sig.map_bound(|sig| { + let state_did = tcx.require_lang_item(LangItem::GeneratorState, None); + let state_adt_ref = tcx.adt_def(state_did); + let state_substs = + tcx.intern_substs(&[sig.yield_ty.into(), sig.return_ty.into()]); + let ret_ty = tcx.mk_adt(state_adt_ref, state_substs); + + tcx.mk_fn_sig( + [env_ty, sig.resume_ty].iter(), + &ret_ty, + false, + hir::Unsafety::Normal, + rustc_target::spec::abi::Abi::Rust, + ) + }) + } + _ => bug!("unexpected type {:?} in Instance::fn_sig", ty), + } + } +} + +pub trait FnAbiExt<'tcx, C> +where + C: LayoutOf<Ty = Ty<'tcx>, TyAndLayout = TyAndLayout<'tcx>> + + HasDataLayout + + HasTargetSpec + + HasTyCtxt<'tcx> + + HasParamEnv<'tcx>, +{ + /// Compute a `FnAbi` suitable for indirect calls, i.e. to `fn` pointers. + /// + /// NB: this doesn't handle virtual calls - those should use `FnAbi::of_instance` + /// instead, where the instance is a `InstanceDef::Virtual`. + fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self; + + /// Compute a `FnAbi` suitable for declaring/defining an `fn` instance, and for + /// direct calls to an `fn`. + /// + /// NB: that includes virtual calls, which are represented by "direct calls" + /// to a `InstanceDef::Virtual` instance (of `<dyn Trait as Trait>::fn`). + fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self; + + fn new_internal( + cx: &C, + sig: ty::PolyFnSig<'tcx>, + extra_args: &[Ty<'tcx>], + caller_location: Option<Ty<'tcx>>, + codegen_fn_attr_flags: CodegenFnAttrFlags, + mk_arg_type: impl Fn(Ty<'tcx>, Option<usize>) -> ArgAbi<'tcx, Ty<'tcx>>, + ) -> Self; + fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi); +} + +fn fn_can_unwind( + panic_strategy: PanicStrategy, + codegen_fn_attr_flags: CodegenFnAttrFlags, + call_conv: Conv, +) -> bool { + if panic_strategy != PanicStrategy::Unwind { + // In panic=abort mode we assume nothing can unwind anywhere, so + // optimize based on this! + false + } else if codegen_fn_attr_flags.contains(CodegenFnAttrFlags::UNWIND) { + // If a specific #[unwind] attribute is present, use that. + true + } else if codegen_fn_attr_flags.contains(CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND) { + // Special attribute for allocator functions, which can't unwind. + false + } else { + if call_conv == Conv::Rust { + // Any Rust method (or `extern "Rust" fn` or `extern + // "rust-call" fn`) is explicitly allowed to unwind + // (unless it has no-unwind attribute, handled above). + true + } else { + // Anything else is either: + // + // 1. A foreign item using a non-Rust ABI (like `extern "C" { fn foo(); }`), or + // + // 2. A Rust item using a non-Rust ABI (like `extern "C" fn foo() { ... }`). + // + // Foreign items (case 1) are assumed to not unwind; it is + // UB otherwise. (At least for now; see also + // rust-lang/rust#63909 and Rust RFC 2753.) + // + // Items defined in Rust with non-Rust ABIs (case 2) are also + // not supposed to unwind. Whether this should be enforced + // (versus stating it is UB) and *how* it would be enforced + // is currently under discussion; see rust-lang/rust#58794. + // + // In either case, we mark item as explicitly nounwind. + false + } + } +} + +impl<'tcx, C> FnAbiExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>> +where + C: LayoutOf<Ty = Ty<'tcx>, TyAndLayout = TyAndLayout<'tcx>> + + HasDataLayout + + HasTargetSpec + + HasTyCtxt<'tcx> + + HasParamEnv<'tcx>, +{ + fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self { + // Assume that fn pointers may always unwind + let codegen_fn_attr_flags = CodegenFnAttrFlags::UNWIND; + + call::FnAbi::new_internal(cx, sig, extra_args, None, codegen_fn_attr_flags, |ty, _| { + ArgAbi::new(cx.layout_of(ty)) + }) + } + + fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self { + let sig = instance.fn_sig_for_fn_abi(cx.tcx()); + + let caller_location = if instance.def.requires_caller_location(cx.tcx()) { + Some(cx.tcx().caller_location_ty()) + } else { + None + }; + + let attrs = cx.tcx().codegen_fn_attrs(instance.def_id()).flags; + + call::FnAbi::new_internal(cx, sig, extra_args, caller_location, attrs, |ty, arg_idx| { + let mut layout = cx.layout_of(ty); + // Don't pass the vtable, it's not an argument of the virtual fn. + // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait` + // or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen + if let (ty::InstanceDef::Virtual(..), Some(0)) = (&instance.def, arg_idx) { + let fat_pointer_ty = if layout.is_unsized() { + // unsized `self` is passed as a pointer to `self` + // FIXME (mikeyhew) change this to use &own if it is ever added to the language + cx.tcx().mk_mut_ptr(layout.ty) + } else { + match layout.abi { + Abi::ScalarPair(..) => (), + _ => bug!("receiver type has unsupported layout: {:?}", layout), + } + + // In the case of Rc<Self>, we need to explicitly pass a *mut RcBox<Self> + // with a Scalar (not ScalarPair) ABI. This is a hack that is understood + // elsewhere in the compiler as a method on a `dyn Trait`. + // To get the type `*mut RcBox<Self>`, we just keep unwrapping newtypes until we + // get a built-in pointer type + let mut fat_pointer_layout = layout; + 'descend_newtypes: while !fat_pointer_layout.ty.is_unsafe_ptr() + && !fat_pointer_layout.ty.is_region_ptr() + { + for i in 0..fat_pointer_layout.fields.count() { + let field_layout = fat_pointer_layout.field(cx, i); + + if !field_layout.is_zst() { + fat_pointer_layout = field_layout; + continue 'descend_newtypes; + } + } + + bug!("receiver has no non-zero-sized fields {:?}", fat_pointer_layout); + } + + fat_pointer_layout.ty + }; + + // we now have a type like `*mut RcBox<dyn Trait>` + // change its layout to that of `*mut ()`, a thin pointer, but keep the same type + // this is understood as a special case elsewhere in the compiler + let unit_pointer_ty = cx.tcx().mk_mut_ptr(cx.tcx().mk_unit()); + layout = cx.layout_of(unit_pointer_ty); + layout.ty = fat_pointer_ty; + } + ArgAbi::new(layout) + }) + } + + fn new_internal( + cx: &C, + sig: ty::PolyFnSig<'tcx>, + extra_args: &[Ty<'tcx>], + caller_location: Option<Ty<'tcx>>, + codegen_fn_attr_flags: CodegenFnAttrFlags, + mk_arg_type: impl Fn(Ty<'tcx>, Option<usize>) -> ArgAbi<'tcx, Ty<'tcx>>, + ) -> Self { + debug!("FnAbi::new_internal({:?}, {:?})", sig, extra_args); + + let sig = cx.tcx().normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), &sig); + + use rustc_target::spec::abi::Abi::*; + let conv = match cx.tcx().sess.target.target.adjust_abi(sig.abi) { + RustIntrinsic | PlatformIntrinsic | Rust | RustCall => Conv::Rust, + + // It's the ABI's job to select this, not ours. + System => bug!("system abi should be selected elsewhere"), + EfiApi => bug!("eficall abi should be selected elsewhere"), + + Stdcall => Conv::X86Stdcall, + Fastcall => Conv::X86Fastcall, + Vectorcall => Conv::X86VectorCall, + Thiscall => Conv::X86ThisCall, + C => Conv::C, + Unadjusted => Conv::C, + Win64 => Conv::X86_64Win64, + SysV64 => Conv::X86_64SysV, + Aapcs => Conv::ArmAapcs, + PtxKernel => Conv::PtxKernel, + Msp430Interrupt => Conv::Msp430Intr, + X86Interrupt => Conv::X86Intr, + AmdGpuKernel => Conv::AmdGpuKernel, + AvrInterrupt => Conv::AvrInterrupt, + AvrNonBlockingInterrupt => Conv::AvrNonBlockingInterrupt, + + // These API constants ought to be more specific... + Cdecl => Conv::C, + }; + + let mut inputs = sig.inputs(); + let extra_args = if sig.abi == RustCall { + assert!(!sig.c_variadic && extra_args.is_empty()); + + if let Some(input) = sig.inputs().last() { + if let ty::Tuple(tupled_arguments) = input.kind { + inputs = &sig.inputs()[0..sig.inputs().len() - 1]; + tupled_arguments.iter().map(|k| k.expect_ty()).collect() + } else { + bug!( + "argument to function with \"rust-call\" ABI \ + is not a tuple" + ); + } + } else { + bug!( + "argument to function with \"rust-call\" ABI \ + is not a tuple" + ); + } + } else { + assert!(sig.c_variadic || extra_args.is_empty()); + extra_args.to_vec() + }; + + let target = &cx.tcx().sess.target.target; + let target_env_gnu_like = matches!(&target.target_env[..], "gnu" | "musl"); + let win_x64_gnu = + target.target_os == "windows" && target.arch == "x86_64" && target.target_env == "gnu"; + let linux_s390x_gnu_like = + target.target_os == "linux" && target.arch == "s390x" && target_env_gnu_like; + let linux_sparc64_gnu_like = + target.target_os == "linux" && target.arch == "sparc64" && target_env_gnu_like; + let linux_powerpc_gnu_like = + target.target_os == "linux" && target.arch == "powerpc" && target_env_gnu_like; + let rust_abi = match sig.abi { + RustIntrinsic | PlatformIntrinsic | Rust | RustCall => true, + _ => false, + }; + + // Handle safe Rust thin and fat pointers. + let adjust_for_rust_scalar = |attrs: &mut ArgAttributes, + scalar: &Scalar, + layout: TyAndLayout<'tcx>, + offset: Size, + is_return: bool| { + // Booleans are always an i1 that needs to be zero-extended. + if scalar.is_bool() { + attrs.set(ArgAttribute::ZExt); + return; + } + + // Only pointer types handled below. + if scalar.value != Pointer { + return; + } + + if scalar.valid_range.start() < scalar.valid_range.end() { + if *scalar.valid_range.start() > 0 { + attrs.set(ArgAttribute::NonNull); + } + } + + if let Some(pointee) = layout.pointee_info_at(cx, offset) { + if let Some(kind) = pointee.safe { + attrs.pointee_align = Some(pointee.align); + + // `Box` (`UniqueBorrowed`) are not necessarily dereferenceable + // for the entire duration of the function as they can be deallocated + // at any time. Set their valid size to 0. + attrs.pointee_size = match kind { + PointerKind::UniqueOwned => Size::ZERO, + _ => pointee.size, + }; + + // `Box` pointer parameters never alias because ownership is transferred + // `&mut` pointer parameters never alias other parameters, + // or mutable global data + // + // `&T` where `T` contains no `UnsafeCell<U>` is immutable, + // and can be marked as both `readonly` and `noalias`, as + // LLVM's definition of `noalias` is based solely on memory + // dependencies rather than pointer equality + let no_alias = match kind { + PointerKind::Shared => false, + PointerKind::UniqueOwned => true, + PointerKind::Frozen | PointerKind::UniqueBorrowed => !is_return, + }; + if no_alias { + attrs.set(ArgAttribute::NoAlias); + } + + if kind == PointerKind::Frozen && !is_return { + attrs.set(ArgAttribute::ReadOnly); + } + } + } + }; + + let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| { + let is_return = arg_idx.is_none(); + let mut arg = mk_arg_type(ty, arg_idx); + if arg.layout.is_zst() { + // For some forsaken reason, x86_64-pc-windows-gnu + // doesn't ignore zero-sized struct arguments. + // The same is true for {s390x,sparc64,powerpc}-unknown-linux-{gnu,musl}. + if is_return + || rust_abi + || (!win_x64_gnu + && !linux_s390x_gnu_like + && !linux_sparc64_gnu_like + && !linux_powerpc_gnu_like) + { + arg.mode = PassMode::Ignore; + } + } + + // FIXME(eddyb) other ABIs don't have logic for scalar pairs. + if !is_return && rust_abi { + if let Abi::ScalarPair(ref a, ref b) = arg.layout.abi { + let mut a_attrs = ArgAttributes::new(); + let mut b_attrs = ArgAttributes::new(); + adjust_for_rust_scalar(&mut a_attrs, a, arg.layout, Size::ZERO, false); + adjust_for_rust_scalar( + &mut b_attrs, + b, + arg.layout, + a.value.size(cx).align_to(b.value.align(cx).abi), + false, + ); + arg.mode = PassMode::Pair(a_attrs, b_attrs); + return arg; + } + } + + if let Abi::Scalar(ref scalar) = arg.layout.abi { + if let PassMode::Direct(ref mut attrs) = arg.mode { + adjust_for_rust_scalar(attrs, scalar, arg.layout, Size::ZERO, is_return); + } + } + + arg + }; + + let mut fn_abi = FnAbi { + ret: arg_of(sig.output(), None), + args: inputs + .iter() + .cloned() + .chain(extra_args) + .chain(caller_location) + .enumerate() + .map(|(i, ty)| arg_of(ty, Some(i))) + .collect(), + c_variadic: sig.c_variadic, + fixed_count: inputs.len(), + conv, + can_unwind: fn_can_unwind(cx.tcx().sess.panic_strategy(), codegen_fn_attr_flags, conv), + }; + fn_abi.adjust_for_abi(cx, sig.abi); + fn_abi + } + + fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) { + if abi == SpecAbi::Unadjusted { + return; + } + + if abi == SpecAbi::Rust + || abi == SpecAbi::RustCall + || abi == SpecAbi::RustIntrinsic + || abi == SpecAbi::PlatformIntrinsic + { + let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>| { + if arg.is_ignore() { + return; + } + + match arg.layout.abi { + Abi::Aggregate { .. } => {} + + // This is a fun case! The gist of what this is doing is + // that we want callers and callees to always agree on the + // ABI of how they pass SIMD arguments. If we were to *not* + // make these arguments indirect then they'd be immediates + // in LLVM, which means that they'd used whatever the + // appropriate ABI is for the callee and the caller. That + // means, for example, if the caller doesn't have AVX + // enabled but the callee does, then passing an AVX argument + // across this boundary would cause corrupt data to show up. + // + // This problem is fixed by unconditionally passing SIMD + // arguments through memory between callers and callees + // which should get them all to agree on ABI regardless of + // target feature sets. Some more information about this + // issue can be found in #44367. + // + // Note that the platform intrinsic ABI is exempt here as + // that's how we connect up to LLVM and it's unstable + // anyway, we control all calls to it in libstd. + Abi::Vector { .. } + if abi != SpecAbi::PlatformIntrinsic + && cx.tcx().sess.target.target.options.simd_types_indirect => + { + arg.make_indirect(); + return; + } + + _ => return, + } + + let size = arg.layout.size; + if arg.layout.is_unsized() || size > Pointer.size(cx) { + arg.make_indirect(); + } else { + // We want to pass small aggregates as immediates, but using + // a LLVM aggregate type for this leads to bad optimizations, + // so we pick an appropriately sized integer type instead. + arg.cast_to(Reg { kind: RegKind::Integer, size }); + } + }; + fixup(&mut self.ret); + for arg in &mut self.args { + fixup(arg); + } + if let PassMode::Indirect(ref mut attrs, _) = self.ret.mode { + attrs.set(ArgAttribute::StructRet); + } + return; + } + + if let Err(msg) = self.adjust_for_cabi(cx, abi) { + cx.tcx().sess.fatal(&msg); + } + } +} diff --git a/compiler/rustc_middle/src/ty/list.rs b/compiler/rustc_middle/src/ty/list.rs new file mode 100644 index 00000000000..83a2bdf90f9 --- /dev/null +++ b/compiler/rustc_middle/src/ty/list.rs @@ -0,0 +1,178 @@ +use crate::arena::Arena; + +use rustc_serialize::{Encodable, Encoder}; + +use std::alloc::Layout; +use std::cmp::Ordering; +use std::fmt; +use std::hash::{Hash, Hasher}; +use std::iter; +use std::mem; +use std::ops::Deref; +use std::ptr; +use std::slice; + +extern "C" { + /// A dummy type used to force `List` to be unsized while not requiring references to it be wide + /// pointers. + type OpaqueListContents; +} + +/// A wrapper for slices with the additional invariant +/// that the slice is interned and no other slice with +/// the same contents can exist in the same context. +/// This means we can use pointer for both +/// equality comparisons and hashing. +/// +/// Unlike slices, The types contained in `List` are expected to be `Copy` +/// and iterating over a `List` returns `T` instead of a reference. +/// +/// Note: `Slice` was already taken by the `Ty`. +#[repr(C)] +pub struct List<T> { + len: usize, + data: [T; 0], + opaque: OpaqueListContents, +} + +unsafe impl<'a, T: 'a> rustc_data_structures::tagged_ptr::Pointer for &'a List<T> { + const BITS: usize = std::mem::align_of::<usize>().trailing_zeros() as usize; + fn into_usize(self) -> usize { + self as *const List<T> as usize + } + unsafe fn from_usize(ptr: usize) -> Self { + &*(ptr as *const List<T>) + } + unsafe fn with_ref<R, F: FnOnce(&Self) -> R>(ptr: usize, f: F) -> R { + // Self: Copy so this is fine + let ptr = Self::from_usize(ptr); + f(&ptr) + } +} + +unsafe impl<T: Sync> Sync for List<T> {} + +impl<T: Copy> List<T> { + #[inline] + pub(super) fn from_arena<'tcx>(arena: &'tcx Arena<'tcx>, slice: &[T]) -> &'tcx List<T> { + assert!(!mem::needs_drop::<T>()); + assert!(mem::size_of::<T>() != 0); + assert!(!slice.is_empty()); + + let (layout, _offset) = + Layout::new::<usize>().extend(Layout::for_value::<[T]>(slice)).unwrap(); + let mem = arena.dropless.alloc_raw(layout); + unsafe { + let result = &mut *(mem as *mut List<T>); + // Write the length + result.len = slice.len(); + + // Write the elements + let arena_slice = slice::from_raw_parts_mut(result.data.as_mut_ptr(), result.len); + arena_slice.copy_from_slice(slice); + + result + } + } + + // If this method didn't exist, we would use `slice.iter` due to + // deref coercion. + // + // This would be weird, as `self.into_iter` iterates over `T` directly. + #[inline(always)] + pub fn iter(&self) -> <&'_ List<T> as IntoIterator>::IntoIter { + self.into_iter() + } +} + +impl<T: fmt::Debug> fmt::Debug for List<T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +impl<S: Encoder, T: Encodable<S>> Encodable<S> for List<T> { + #[inline] + fn encode(&self, s: &mut S) -> Result<(), S::Error> { + (**self).encode(s) + } +} + +impl<S: Encoder, T: Encodable<S>> Encodable<S> for &List<T> { + #[inline] + fn encode(&self, s: &mut S) -> Result<(), S::Error> { + (**self).encode(s) + } +} + +impl<T> Ord for List<T> +where + T: Ord, +{ + fn cmp(&self, other: &List<T>) -> Ordering { + if self == other { Ordering::Equal } else { <[T] as Ord>::cmp(&**self, &**other) } + } +} + +impl<T> PartialOrd for List<T> +where + T: PartialOrd, +{ + fn partial_cmp(&self, other: &List<T>) -> Option<Ordering> { + if self == other { + Some(Ordering::Equal) + } else { + <[T] as PartialOrd>::partial_cmp(&**self, &**other) + } + } +} + +impl<T: PartialEq> PartialEq for List<T> { + #[inline] + fn eq(&self, other: &List<T>) -> bool { + ptr::eq(self, other) + } +} +impl<T: Eq> Eq for List<T> {} + +impl<T> Hash for List<T> { + #[inline] + fn hash<H: Hasher>(&self, s: &mut H) { + (self as *const List<T>).hash(s) + } +} + +impl<T> Deref for List<T> { + type Target = [T]; + #[inline(always)] + fn deref(&self) -> &[T] { + self.as_ref() + } +} + +impl<T> AsRef<[T]> for List<T> { + #[inline(always)] + fn as_ref(&self) -> &[T] { + unsafe { slice::from_raw_parts(self.data.as_ptr(), self.len) } + } +} + +impl<'a, T: Copy> IntoIterator for &'a List<T> { + type Item = T; + type IntoIter = iter::Copied<<&'a [T] as IntoIterator>::IntoIter>; + #[inline(always)] + fn into_iter(self) -> Self::IntoIter { + self[..].iter().copied() + } +} + +impl<T> List<T> { + #[inline(always)] + pub fn empty<'a>() -> &'a List<T> { + #[repr(align(64), C)] + struct EmptySlice([u8; 64]); + static EMPTY_SLICE: EmptySlice = EmptySlice([0; 64]); + assert!(mem::align_of::<T>() <= 64); + unsafe { &*(&EMPTY_SLICE as *const _ as *const List<T>) } + } +} diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs new file mode 100644 index 00000000000..b6300a40b0d --- /dev/null +++ b/compiler/rustc_middle/src/ty/mod.rs @@ -0,0 +1,3146 @@ +// ignore-tidy-filelength +pub use self::fold::{TypeFoldable, TypeFolder, TypeVisitor}; +pub use self::AssocItemContainer::*; +pub use self::BorrowKind::*; +pub use self::IntVarValue::*; +pub use self::Variance::*; + +use crate::hir::exports::ExportMap; +use crate::ich::StableHashingContext; +use crate::infer::canonical::Canonical; +use crate::middle::cstore::CrateStoreDyn; +use crate::middle::resolve_lifetime::ObjectLifetimeDefault; +use crate::mir::interpret::ErrorHandled; +use crate::mir::Body; +use crate::mir::GeneratorLayout; +use crate::traits::{self, Reveal}; +use crate::ty; +use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef}; +use crate::ty::util::{Discr, IntTypeExt}; +use rustc_ast as ast; +use rustc_attr as attr; +use rustc_data_structures::captures::Captures; +use rustc_data_structures::fingerprint::Fingerprint; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::fx::FxHashSet; +use rustc_data_structures::fx::FxIndexMap; +use rustc_data_structures::sorted_map::SortedIndexMultiMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_data_structures::sync::{self, par_iter, ParallelIterator}; +use rustc_data_structures::tagged_ptr::CopyTaggedPtr; +use rustc_errors::ErrorReported; +use rustc_hir as hir; +use rustc_hir::def::{CtorKind, CtorOf, DefKind, Namespace, Res}; +use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX}; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{Constness, Node}; +use rustc_index::vec::{Idx, IndexVec}; +use rustc_macros::HashStable; +use rustc_serialize::{self, Encodable, Encoder}; +use rustc_session::DataTypeKind; +use rustc_span::hygiene::ExpnId; +use rustc_span::symbol::{kw, sym, Ident, Symbol}; +use rustc_span::Span; +use rustc_target::abi::{Align, VariantIdx}; + +use std::cell::RefCell; +use std::cmp::Ordering; +use std::fmt; +use std::hash::{Hash, Hasher}; +use std::ops::Range; +use std::ptr; +use std::str; + +pub use self::sty::BoundRegion::*; +pub use self::sty::InferTy::*; +pub use self::sty::RegionKind; +pub use self::sty::RegionKind::*; +pub use self::sty::TyKind::*; +pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar, DebruijnIndex, INNERMOST}; +pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region}; +pub use self::sty::{CanonicalPolyFnSig, FnSig, GenSig, PolyFnSig, PolyGenSig}; +pub use self::sty::{ClosureSubsts, GeneratorSubsts, TypeAndMut, UpvarSubsts}; +pub use self::sty::{ClosureSubstsParts, GeneratorSubstsParts}; +pub use self::sty::{ConstVid, FloatVid, IntVid, RegionVid, TyVid}; +pub use self::sty::{ExistentialPredicate, InferTy, ParamConst, ParamTy, ProjectionTy}; +pub use self::sty::{ExistentialProjection, PolyExistentialProjection}; +pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef}; +pub use self::sty::{PolyTraitRef, TraitRef, TyKind}; +pub use crate::ty::diagnostics::*; + +pub use self::binding::BindingMode; +pub use self::binding::BindingMode::*; + +pub use self::context::{tls, FreeRegionInfo, TyCtxt}; +pub use self::context::{ + CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, + DelaySpanBugEmitted, ResolvedOpaqueTy, UserType, UserTypeAnnotationIndex, +}; +pub use self::context::{ + CtxtInterners, GeneratorInteriorTypeCause, GlobalCtxt, Lift, TypeckResults, +}; + +pub use self::instance::{Instance, InstanceDef}; + +pub use self::list::List; + +pub use self::trait_def::TraitDef; + +pub use self::query::queries; + +pub use self::consts::{Const, ConstInt, ConstKind, InferConst}; + +pub mod _match; +pub mod adjustment; +pub mod binding; +pub mod cast; +pub mod codec; +mod erase_regions; +pub mod error; +pub mod fast_reject; +pub mod flags; +pub mod fold; +pub mod inhabitedness; +pub mod layout; +pub mod normalize_erasing_regions; +pub mod outlives; +pub mod print; +pub mod query; +pub mod relate; +pub mod steal; +pub mod subst; +pub mod trait_def; +pub mod util; +pub mod walk; + +mod consts; +mod context; +mod diagnostics; +mod instance; +mod list; +mod structural_impls; +mod sty; + +// Data types + +pub struct ResolverOutputs { + pub definitions: rustc_hir::definitions::Definitions, + pub cstore: Box<CrateStoreDyn>, + pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>, + pub maybe_unused_trait_imports: FxHashSet<LocalDefId>, + pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>, + pub export_map: ExportMap<LocalDefId>, + pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>, + /// Extern prelude entries. The value is `true` if the entry was introduced + /// via `extern crate` item and not `--extern` option or compiler built-in. + pub extern_prelude: FxHashMap<Symbol, bool>, +} + +#[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable, Hash)] +pub enum AssocItemContainer { + TraitContainer(DefId), + ImplContainer(DefId), +} + +impl AssocItemContainer { + /// Asserts that this is the `DefId` of an associated item declared + /// in a trait, and returns the trait `DefId`. + pub fn assert_trait(&self) -> DefId { + match *self { + TraitContainer(id) => id, + _ => bug!("associated item has wrong container type: {:?}", self), + } + } + + pub fn id(&self) -> DefId { + match *self { + TraitContainer(id) => id, + ImplContainer(id) => id, + } + } +} + +/// The "header" of an impl is everything outside the body: a Self type, a trait +/// ref (in the case of a trait impl), and a set of predicates (from the +/// bounds / where-clauses). +#[derive(Clone, Debug, TypeFoldable)] +pub struct ImplHeader<'tcx> { + pub impl_def_id: DefId, + pub self_ty: Ty<'tcx>, + pub trait_ref: Option<TraitRef<'tcx>>, + pub predicates: Vec<Predicate<'tcx>>, +} + +#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable)] +pub enum ImplPolarity { + /// `impl Trait for Type` + Positive, + /// `impl !Trait for Type` + Negative, + /// `#[rustc_reservation_impl] impl Trait for Type` + /// + /// This is a "stability hack", not a real Rust feature. + /// See #64631 for details. + Reservation, +} + +#[derive(Copy, Clone, Debug, PartialEq, HashStable, Eq, Hash)] +pub struct AssocItem { + pub def_id: DefId, + #[stable_hasher(project(name))] + pub ident: Ident, + pub kind: AssocKind, + pub vis: Visibility, + pub defaultness: hir::Defaultness, + pub container: AssocItemContainer, + + /// Whether this is a method with an explicit self + /// as its first parameter, allowing method calls. + pub fn_has_self_parameter: bool, +} + +#[derive(Copy, Clone, PartialEq, Debug, HashStable, Eq, Hash)] +pub enum AssocKind { + Const, + Fn, + Type, +} + +impl AssocKind { + pub fn namespace(&self) -> Namespace { + match *self { + ty::AssocKind::Type => Namespace::TypeNS, + ty::AssocKind::Const | ty::AssocKind::Fn => Namespace::ValueNS, + } + } + + pub fn as_def_kind(&self) -> DefKind { + match self { + AssocKind::Const => DefKind::AssocConst, + AssocKind::Fn => DefKind::AssocFn, + AssocKind::Type => DefKind::AssocTy, + } + } +} + +impl AssocItem { + pub fn signature(&self, tcx: TyCtxt<'_>) -> String { + match self.kind { + ty::AssocKind::Fn => { + // We skip the binder here because the binder would deanonymize all + // late-bound regions, and we don't want method signatures to show up + // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound + // regions just fine, showing `fn(&MyType)`. + tcx.fn_sig(self.def_id).skip_binder().to_string() + } + ty::AssocKind::Type => format!("type {};", self.ident), + ty::AssocKind::Const => { + format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id)) + } + } + } +} + +/// A list of `ty::AssocItem`s in definition order that allows for efficient lookup by name. +/// +/// When doing lookup by name, we try to postpone hygienic comparison for as long as possible since +/// it is relatively expensive. Instead, items are indexed by `Symbol` and hygienic comparison is +/// done only on items with the same name. +#[derive(Debug, Clone, PartialEq, HashStable)] +pub struct AssociatedItems<'tcx> { + items: SortedIndexMultiMap<u32, Symbol, &'tcx ty::AssocItem>, +} + +impl<'tcx> AssociatedItems<'tcx> { + /// Constructs an `AssociatedItems` map from a series of `ty::AssocItem`s in definition order. + pub fn new(items_in_def_order: impl IntoIterator<Item = &'tcx ty::AssocItem>) -> Self { + let items = items_in_def_order.into_iter().map(|item| (item.ident.name, item)).collect(); + AssociatedItems { items } + } + + /// Returns a slice of associated items in the order they were defined. + /// + /// New code should avoid relying on definition order. If you need a particular associated item + /// for a known trait, make that trait a lang item instead of indexing this array. + pub fn in_definition_order(&self) -> impl '_ + Iterator<Item = &ty::AssocItem> { + self.items.iter().map(|(_, v)| *v) + } + + /// Returns an iterator over all associated items with the given name, ignoring hygiene. + pub fn filter_by_name_unhygienic( + &self, + name: Symbol, + ) -> impl '_ + Iterator<Item = &ty::AssocItem> { + self.items.get_by_key(&name).copied() + } + + /// Returns an iterator over all associated items with the given name. + /// + /// Multiple items may have the same name if they are in different `Namespace`s. For example, + /// an associated type can have the same name as a method. Use one of the `find_by_name_and_*` + /// methods below if you know which item you are looking for. + pub fn filter_by_name( + &'a self, + tcx: TyCtxt<'a>, + ident: Ident, + parent_def_id: DefId, + ) -> impl 'a + Iterator<Item = &'a ty::AssocItem> { + self.filter_by_name_unhygienic(ident.name) + .filter(move |item| tcx.hygienic_eq(ident, item.ident, parent_def_id)) + } + + /// Returns the associated item with the given name and `AssocKind`, if one exists. + pub fn find_by_name_and_kind( + &self, + tcx: TyCtxt<'_>, + ident: Ident, + kind: AssocKind, + parent_def_id: DefId, + ) -> Option<&ty::AssocItem> { + self.filter_by_name_unhygienic(ident.name) + .filter(|item| item.kind == kind) + .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id)) + } + + /// Returns the associated item with the given name in the given `Namespace`, if one exists. + pub fn find_by_name_and_namespace( + &self, + tcx: TyCtxt<'_>, + ident: Ident, + ns: Namespace, + parent_def_id: DefId, + ) -> Option<&ty::AssocItem> { + self.filter_by_name_unhygienic(ident.name) + .filter(|item| item.kind.namespace() == ns) + .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id)) + } +} + +#[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)] +pub enum Visibility { + /// Visible everywhere (including in other crates). + Public, + /// Visible only in the given crate-local module. + Restricted(DefId), + /// Not visible anywhere in the local crate. This is the visibility of private external items. + Invisible, +} + +pub trait DefIdTree: Copy { + fn parent(self, id: DefId) -> Option<DefId>; + + fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool { + if descendant.krate != ancestor.krate { + return false; + } + + while descendant != ancestor { + match self.parent(descendant) { + Some(parent) => descendant = parent, + None => return false, + } + } + true + } +} + +impl<'tcx> DefIdTree for TyCtxt<'tcx> { + fn parent(self, id: DefId) -> Option<DefId> { + self.def_key(id).parent.map(|index| DefId { index, ..id }) + } +} + +impl Visibility { + pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self { + match visibility.node { + hir::VisibilityKind::Public => Visibility::Public, + hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)), + hir::VisibilityKind::Restricted { ref path, .. } => match path.res { + // If there is no resolution, `resolve` will have already reported an error, so + // assume that the visibility is public to avoid reporting more privacy errors. + Res::Err => Visibility::Public, + def => Visibility::Restricted(def.def_id()), + }, + hir::VisibilityKind::Inherited => { + Visibility::Restricted(tcx.parent_module(id).to_def_id()) + } + } + } + + /// Returns `true` if an item with this visibility is accessible from the given block. + pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool { + let restriction = match self { + // Public items are visible everywhere. + Visibility::Public => return true, + // Private items from other crates are visible nowhere. + Visibility::Invisible => return false, + // Restricted items are visible in an arbitrary local module. + Visibility::Restricted(other) if other.krate != module.krate => return false, + Visibility::Restricted(module) => module, + }; + + tree.is_descendant_of(module, restriction) + } + + /// Returns `true` if this visibility is at least as accessible as the given visibility + pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool { + let vis_restriction = match vis { + Visibility::Public => return self == Visibility::Public, + Visibility::Invisible => return true, + Visibility::Restricted(module) => module, + }; + + self.is_accessible_from(vis_restriction, tree) + } + + // Returns `true` if this item is visible anywhere in the local crate. + pub fn is_visible_locally(self) -> bool { + match self { + Visibility::Public => true, + Visibility::Restricted(def_id) => def_id.is_local(), + Visibility::Invisible => false, + } + } +} + +#[derive(Copy, Clone, PartialEq, TyDecodable, TyEncodable, HashStable)] +pub enum Variance { + Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type + Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell + Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type + Bivariant, // T<A> <: T<B> -- e.g., unused type parameter +} + +/// The crate variances map is computed during typeck and contains the +/// variance of every item in the local crate. You should not use it +/// directly, because to do so will make your pass dependent on the +/// HIR of every item in the local crate. Instead, use +/// `tcx.variances_of()` to get the variance for a *particular* +/// item. +#[derive(HashStable)] +pub struct CrateVariancesMap<'tcx> { + /// For each item with generics, maps to a vector of the variance + /// of its generics. If an item has no generics, it will have no + /// entry. + pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>, +} + +impl Variance { + /// `a.xform(b)` combines the variance of a context with the + /// variance of a type with the following meaning. If we are in a + /// context with variance `a`, and we encounter a type argument in + /// a position with variance `b`, then `a.xform(b)` is the new + /// variance with which the argument appears. + /// + /// Example 1: + /// + /// *mut Vec<i32> + /// + /// Here, the "ambient" variance starts as covariant. `*mut T` is + /// invariant with respect to `T`, so the variance in which the + /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which + /// yields `Invariant`. Now, the type `Vec<T>` is covariant with + /// respect to its type argument `T`, and hence the variance of + /// the `i32` here is `Invariant.xform(Covariant)`, which results + /// (again) in `Invariant`. + /// + /// Example 2: + /// + /// fn(*const Vec<i32>, *mut Vec<i32) + /// + /// The ambient variance is covariant. A `fn` type is + /// contravariant with respect to its parameters, so the variance + /// within which both pointer types appear is + /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const + /// T` is covariant with respect to `T`, so the variance within + /// which the first `Vec<i32>` appears is + /// `Contravariant.xform(Covariant)` or `Contravariant`. The same + /// is true for its `i32` argument. In the `*mut T` case, the + /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`, + /// and hence the outermost type is `Invariant` with respect to + /// `Vec<i32>` (and its `i32` argument). + /// + /// Source: Figure 1 of "Taming the Wildcards: + /// Combining Definition- and Use-Site Variance" published in PLDI'11. + pub fn xform(self, v: ty::Variance) -> ty::Variance { + match (self, v) { + // Figure 1, column 1. + (ty::Covariant, ty::Covariant) => ty::Covariant, + (ty::Covariant, ty::Contravariant) => ty::Contravariant, + (ty::Covariant, ty::Invariant) => ty::Invariant, + (ty::Covariant, ty::Bivariant) => ty::Bivariant, + + // Figure 1, column 2. + (ty::Contravariant, ty::Covariant) => ty::Contravariant, + (ty::Contravariant, ty::Contravariant) => ty::Covariant, + (ty::Contravariant, ty::Invariant) => ty::Invariant, + (ty::Contravariant, ty::Bivariant) => ty::Bivariant, + + // Figure 1, column 3. + (ty::Invariant, _) => ty::Invariant, + + // Figure 1, column 4. + (ty::Bivariant, _) => ty::Bivariant, + } + } +} + +// Contains information needed to resolve types and (in the future) look up +// the types of AST nodes. +#[derive(Copy, Clone, PartialEq, Eq, Hash)] +pub struct CReaderCacheKey { + pub cnum: CrateNum, + pub pos: usize, +} + +bitflags! { + /// Flags that we track on types. These flags are propagated upwards + /// through the type during type construction, so that we can quickly check + /// whether the type has various kinds of types in it without recursing + /// over the type itself. + pub struct TypeFlags: u32 { + // Does this have parameters? Used to determine whether substitution is + // required. + /// Does this have [Param]? + const HAS_TY_PARAM = 1 << 0; + /// Does this have [ReEarlyBound]? + const HAS_RE_PARAM = 1 << 1; + /// Does this have [ConstKind::Param]? + const HAS_CT_PARAM = 1 << 2; + + const NEEDS_SUBST = TypeFlags::HAS_TY_PARAM.bits + | TypeFlags::HAS_RE_PARAM.bits + | TypeFlags::HAS_CT_PARAM.bits; + + /// Does this have [Infer]? + const HAS_TY_INFER = 1 << 3; + /// Does this have [ReVar]? + const HAS_RE_INFER = 1 << 4; + /// Does this have [ConstKind::Infer]? + const HAS_CT_INFER = 1 << 5; + + /// Does this have inference variables? Used to determine whether + /// inference is required. + const NEEDS_INFER = TypeFlags::HAS_TY_INFER.bits + | TypeFlags::HAS_RE_INFER.bits + | TypeFlags::HAS_CT_INFER.bits; + + /// Does this have [Placeholder]? + const HAS_TY_PLACEHOLDER = 1 << 6; + /// Does this have [RePlaceholder]? + const HAS_RE_PLACEHOLDER = 1 << 7; + /// Does this have [ConstKind::Placeholder]? + const HAS_CT_PLACEHOLDER = 1 << 8; + + /// `true` if there are "names" of regions and so forth + /// that are local to a particular fn/inferctxt + const HAS_FREE_LOCAL_REGIONS = 1 << 9; + + /// `true` if there are "names" of types and regions and so forth + /// that are local to a particular fn + const HAS_FREE_LOCAL_NAMES = TypeFlags::HAS_TY_PARAM.bits + | TypeFlags::HAS_CT_PARAM.bits + | TypeFlags::HAS_TY_INFER.bits + | TypeFlags::HAS_CT_INFER.bits + | TypeFlags::HAS_TY_PLACEHOLDER.bits + | TypeFlags::HAS_CT_PLACEHOLDER.bits + | TypeFlags::HAS_FREE_LOCAL_REGIONS.bits; + + /// Does this have [Projection]? + const HAS_TY_PROJECTION = 1 << 10; + /// Does this have [Opaque]? + const HAS_TY_OPAQUE = 1 << 11; + /// Does this have [ConstKind::Unevaluated]? + const HAS_CT_PROJECTION = 1 << 12; + + /// Could this type be normalized further? + const HAS_PROJECTION = TypeFlags::HAS_TY_PROJECTION.bits + | TypeFlags::HAS_TY_OPAQUE.bits + | TypeFlags::HAS_CT_PROJECTION.bits; + + /// Is an error type/const reachable? + const HAS_ERROR = 1 << 13; + + /// Does this have any region that "appears free" in the type? + /// Basically anything but [ReLateBound] and [ReErased]. + const HAS_FREE_REGIONS = 1 << 14; + + /// Does this have any [ReLateBound] regions? Used to check + /// if a global bound is safe to evaluate. + const HAS_RE_LATE_BOUND = 1 << 15; + + /// Does this have any [ReErased] regions? + const HAS_RE_ERASED = 1 << 16; + + /// Does this value have parameters/placeholders/inference variables which could be + /// replaced later, in a way that would change the results of `impl` specialization? + const STILL_FURTHER_SPECIALIZABLE = 1 << 17; + } +} + +#[allow(rustc::usage_of_ty_tykind)] +pub struct TyS<'tcx> { + pub kind: TyKind<'tcx>, + pub flags: TypeFlags, + + /// This is a kind of confusing thing: it stores the smallest + /// binder such that + /// + /// (a) the binder itself captures nothing but + /// (b) all the late-bound things within the type are captured + /// by some sub-binder. + /// + /// So, for a type without any late-bound things, like `u32`, this + /// will be *innermost*, because that is the innermost binder that + /// captures nothing. But for a type `&'D u32`, where `'D` is a + /// late-bound region with De Bruijn index `D`, this would be `D + 1` + /// -- the binder itself does not capture `D`, but `D` is captured + /// by an inner binder. + /// + /// We call this concept an "exclusive" binder `D` because all + /// De Bruijn indices within the type are contained within `0..D` + /// (exclusive). + outer_exclusive_binder: ty::DebruijnIndex, +} + +// `TyS` is used a lot. Make sure it doesn't unintentionally get bigger. +#[cfg(target_arch = "x86_64")] +static_assert_size!(TyS<'_>, 32); + +impl<'tcx> Ord for TyS<'tcx> { + fn cmp(&self, other: &TyS<'tcx>) -> Ordering { + self.kind.cmp(&other.kind) + } +} + +impl<'tcx> PartialOrd for TyS<'tcx> { + fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> { + Some(self.kind.cmp(&other.kind)) + } +} + +impl<'tcx> PartialEq for TyS<'tcx> { + #[inline] + fn eq(&self, other: &TyS<'tcx>) -> bool { + ptr::eq(self, other) + } +} +impl<'tcx> Eq for TyS<'tcx> {} + +impl<'tcx> Hash for TyS<'tcx> { + fn hash<H: Hasher>(&self, s: &mut H) { + (self as *const TyS<'_>).hash(s) + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let ty::TyS { + ref kind, + + // The other fields just provide fast access to information that is + // also contained in `kind`, so no need to hash them. + flags: _, + + outer_exclusive_binder: _, + } = *self; + + kind.hash_stable(hcx, hasher); + } +} + +#[rustc_diagnostic_item = "Ty"] +pub type Ty<'tcx> = &'tcx TyS<'tcx>; + +pub type CanonicalTy<'tcx> = Canonical<'tcx, Ty<'tcx>>; + +#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)] +pub struct UpvarPath { + pub hir_id: hir::HirId, +} + +/// Upvars do not get their own `NodeId`. Instead, we use the pair of +/// the original var ID (that is, the root variable that is referenced +/// by the upvar) and the ID of the closure expression. +#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)] +pub struct UpvarId { + pub var_path: UpvarPath, + pub closure_expr_id: LocalDefId, +} + +#[derive(Clone, PartialEq, Debug, TyEncodable, TyDecodable, Copy, HashStable)] +pub enum BorrowKind { + /// Data must be immutable and is aliasable. + ImmBorrow, + + /// Data must be immutable but not aliasable. This kind of borrow + /// cannot currently be expressed by the user and is used only in + /// implicit closure bindings. It is needed when the closure + /// is borrowing or mutating a mutable referent, e.g.: + /// + /// let x: &mut isize = ...; + /// let y = || *x += 5; + /// + /// If we were to try to translate this closure into a more explicit + /// form, we'd encounter an error with the code as written: + /// + /// struct Env { x: & &mut isize } + /// let x: &mut isize = ...; + /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn + /// fn fn_ptr(env: &mut Env) { **env.x += 5; } + /// + /// This is then illegal because you cannot mutate a `&mut` found + /// in an aliasable location. To solve, you'd have to translate with + /// an `&mut` borrow: + /// + /// struct Env { x: & &mut isize } + /// let x: &mut isize = ...; + /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x + /// fn fn_ptr(env: &mut Env) { **env.x += 5; } + /// + /// Now the assignment to `**env.x` is legal, but creating a + /// mutable pointer to `x` is not because `x` is not mutable. We + /// could fix this by declaring `x` as `let mut x`. This is ok in + /// user code, if awkward, but extra weird for closures, since the + /// borrow is hidden. + /// + /// So we introduce a "unique imm" borrow -- the referent is + /// immutable, but not aliasable. This solves the problem. For + /// simplicity, we don't give users the way to express this + /// borrow, it's just used when translating closures. + UniqueImmBorrow, + + /// Data is mutable and not aliasable. + MutBorrow, +} + +/// Information describing the capture of an upvar. This is computed +/// during `typeck`, specifically by `regionck`. +#[derive(PartialEq, Clone, Debug, Copy, TyEncodable, TyDecodable, HashStable)] +pub enum UpvarCapture<'tcx> { + /// Upvar is captured by value. This is always true when the + /// closure is labeled `move`, but can also be true in other cases + /// depending on inference. + /// + /// If the upvar was inferred to be captured by value (e.g. `move` + /// was not used), then the `Span` points to a usage that + /// required it. There may be more than one such usage + /// (e.g. `|| { a; a; }`), in which case we pick an + /// arbitrary one. + ByValue(Option<Span>), + + /// Upvar is captured by reference. + ByRef(UpvarBorrow<'tcx>), +} + +#[derive(PartialEq, Clone, Copy, TyEncodable, TyDecodable, HashStable)] +pub struct UpvarBorrow<'tcx> { + /// The kind of borrow: by-ref upvars have access to shared + /// immutable borrows, which are not part of the normal language + /// syntax. + pub kind: BorrowKind, + + /// Region of the resulting reference. + pub region: ty::Region<'tcx>, +} + +pub type UpvarListMap = FxHashMap<DefId, FxIndexMap<hir::HirId, UpvarId>>; +pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>; + +#[derive(Clone, Copy, PartialEq, Eq)] +pub enum IntVarValue { + IntType(ast::IntTy), + UintType(ast::UintTy), +} + +#[derive(Clone, Copy, PartialEq, Eq)] +pub struct FloatVarValue(pub ast::FloatTy); + +impl ty::EarlyBoundRegion { + pub fn to_bound_region(&self) -> ty::BoundRegion { + ty::BoundRegion::BrNamed(self.def_id, self.name) + } + + /// Does this early bound region have a name? Early bound regions normally + /// always have names except when using anonymous lifetimes (`'_`). + pub fn has_name(&self) -> bool { + self.name != kw::UnderscoreLifetime + } +} + +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum GenericParamDefKind { + Lifetime, + Type { + has_default: bool, + object_lifetime_default: ObjectLifetimeDefault, + synthetic: Option<hir::SyntheticTyParamKind>, + }, + Const, +} + +impl GenericParamDefKind { + pub fn descr(&self) -> &'static str { + match self { + GenericParamDefKind::Lifetime => "lifetime", + GenericParamDefKind::Type { .. } => "type", + GenericParamDefKind::Const => "constant", + } + } +} + +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct GenericParamDef { + pub name: Symbol, + pub def_id: DefId, + pub index: u32, + + /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute + /// on generic parameter `'a`/`T`, asserts data behind the parameter + /// `'a`/`T` won't be accessed during the parent type's `Drop` impl. + pub pure_wrt_drop: bool, + + pub kind: GenericParamDefKind, +} + +impl GenericParamDef { + pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion { + if let GenericParamDefKind::Lifetime = self.kind { + ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name } + } else { + bug!("cannot convert a non-lifetime parameter def to an early bound region") + } + } + + pub fn to_bound_region(&self) -> ty::BoundRegion { + if let GenericParamDefKind::Lifetime = self.kind { + self.to_early_bound_region_data().to_bound_region() + } else { + bug!("cannot convert a non-lifetime parameter def to an early bound region") + } + } +} + +#[derive(Default)] +pub struct GenericParamCount { + pub lifetimes: usize, + pub types: usize, + pub consts: usize, +} + +/// Information about the formal type/lifetime parameters associated +/// with an item or method. Analogous to `hir::Generics`. +/// +/// The ordering of parameters is the same as in `Subst` (excluding child generics): +/// `Self` (optionally), `Lifetime` params..., `Type` params... +#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct Generics { + pub parent: Option<DefId>, + pub parent_count: usize, + pub params: Vec<GenericParamDef>, + + /// Reverse map to the `index` field of each `GenericParamDef`. + #[stable_hasher(ignore)] + pub param_def_id_to_index: FxHashMap<DefId, u32>, + + pub has_self: bool, + pub has_late_bound_regions: Option<Span>, +} + +impl<'tcx> Generics { + pub fn count(&self) -> usize { + self.parent_count + self.params.len() + } + + pub fn own_counts(&self) -> GenericParamCount { + // We could cache this as a property of `GenericParamCount`, but + // the aim is to refactor this away entirely eventually and the + // presence of this method will be a constant reminder. + let mut own_counts: GenericParamCount = Default::default(); + + for param in &self.params { + match param.kind { + GenericParamDefKind::Lifetime => own_counts.lifetimes += 1, + GenericParamDefKind::Type { .. } => own_counts.types += 1, + GenericParamDefKind::Const => own_counts.consts += 1, + }; + } + + own_counts + } + + pub fn requires_monomorphization(&self, tcx: TyCtxt<'tcx>) -> bool { + if self.own_requires_monomorphization() { + return true; + } + + if let Some(parent_def_id) = self.parent { + let parent = tcx.generics_of(parent_def_id); + parent.requires_monomorphization(tcx) + } else { + false + } + } + + pub fn own_requires_monomorphization(&self) -> bool { + for param in &self.params { + match param.kind { + GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true, + GenericParamDefKind::Lifetime => {} + } + } + false + } + + /// Returns the `GenericParamDef` with the given index. + pub fn param_at(&'tcx self, param_index: usize, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef { + if let Some(index) = param_index.checked_sub(self.parent_count) { + &self.params[index] + } else { + tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?")) + .param_at(param_index, tcx) + } + } + + /// Returns the `GenericParamDef` associated with this `EarlyBoundRegion`. + pub fn region_param( + &'tcx self, + param: &EarlyBoundRegion, + tcx: TyCtxt<'tcx>, + ) -> &'tcx GenericParamDef { + let param = self.param_at(param.index as usize, tcx); + match param.kind { + GenericParamDefKind::Lifetime => param, + _ => bug!("expected lifetime parameter, but found another generic parameter"), + } + } + + /// Returns the `GenericParamDef` associated with this `ParamTy`. + pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef { + let param = self.param_at(param.index as usize, tcx); + match param.kind { + GenericParamDefKind::Type { .. } => param, + _ => bug!("expected type parameter, but found another generic parameter"), + } + } + + /// Returns the `GenericParamDef` associated with this `ParamConst`. + pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef { + let param = self.param_at(param.index as usize, tcx); + match param.kind { + GenericParamDefKind::Const => param, + _ => bug!("expected const parameter, but found another generic parameter"), + } + } +} + +/// Bounds on generics. +#[derive(Copy, Clone, Default, Debug, TyEncodable, TyDecodable, HashStable)] +pub struct GenericPredicates<'tcx> { + pub parent: Option<DefId>, + pub predicates: &'tcx [(Predicate<'tcx>, Span)], +} + +impl<'tcx> GenericPredicates<'tcx> { + pub fn instantiate( + &self, + tcx: TyCtxt<'tcx>, + substs: SubstsRef<'tcx>, + ) -> InstantiatedPredicates<'tcx> { + let mut instantiated = InstantiatedPredicates::empty(); + self.instantiate_into(tcx, &mut instantiated, substs); + instantiated + } + + pub fn instantiate_own( + &self, + tcx: TyCtxt<'tcx>, + substs: SubstsRef<'tcx>, + ) -> InstantiatedPredicates<'tcx> { + InstantiatedPredicates { + predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(), + spans: self.predicates.iter().map(|(_, sp)| *sp).collect(), + } + } + + fn instantiate_into( + &self, + tcx: TyCtxt<'tcx>, + instantiated: &mut InstantiatedPredicates<'tcx>, + substs: SubstsRef<'tcx>, + ) { + if let Some(def_id) = self.parent { + tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs); + } + instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p.subst(tcx, substs))); + instantiated.spans.extend(self.predicates.iter().map(|(_, sp)| *sp)); + } + + pub fn instantiate_identity(&self, tcx: TyCtxt<'tcx>) -> InstantiatedPredicates<'tcx> { + let mut instantiated = InstantiatedPredicates::empty(); + self.instantiate_identity_into(tcx, &mut instantiated); + instantiated + } + + fn instantiate_identity_into( + &self, + tcx: TyCtxt<'tcx>, + instantiated: &mut InstantiatedPredicates<'tcx>, + ) { + if let Some(def_id) = self.parent { + tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated); + } + instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p)); + instantiated.spans.extend(self.predicates.iter().map(|(_, s)| s)); + } + + pub fn instantiate_supertrait( + &self, + tcx: TyCtxt<'tcx>, + poly_trait_ref: &ty::PolyTraitRef<'tcx>, + ) -> InstantiatedPredicates<'tcx> { + assert_eq!(self.parent, None); + InstantiatedPredicates { + predicates: self + .predicates + .iter() + .map(|(pred, _)| pred.subst_supertrait(tcx, poly_trait_ref)) + .collect(), + spans: self.predicates.iter().map(|(_, sp)| *sp).collect(), + } + } +} + +#[derive(Debug)] +crate struct PredicateInner<'tcx> { + kind: PredicateKind<'tcx>, + flags: TypeFlags, + /// See the comment for the corresponding field of [TyS]. + outer_exclusive_binder: ty::DebruijnIndex, +} + +#[cfg(target_arch = "x86_64")] +static_assert_size!(PredicateInner<'_>, 48); + +#[derive(Clone, Copy, Lift)] +pub struct Predicate<'tcx> { + inner: &'tcx PredicateInner<'tcx>, +} + +impl<'tcx> PartialEq for Predicate<'tcx> { + fn eq(&self, other: &Self) -> bool { + // `self.kind` is always interned. + ptr::eq(self.inner, other.inner) + } +} + +impl Hash for Predicate<'_> { + fn hash<H: Hasher>(&self, s: &mut H) { + (self.inner as *const PredicateInner<'_>).hash(s) + } +} + +impl<'tcx> Eq for Predicate<'tcx> {} + +impl<'tcx> Predicate<'tcx> { + #[inline(always)] + pub fn kind(self) -> &'tcx PredicateKind<'tcx> { + &self.inner.kind + } + + /// Returns the inner `PredicateAtom`. + /// + /// The returned atom may contain unbound variables bound to binders skipped in this method. + /// It is safe to reapply binders to the given atom. + /// + /// Note that this method panics in case this predicate has unbound variables. + pub fn skip_binders(self) -> PredicateAtom<'tcx> { + match self.kind() { + &PredicateKind::ForAll(binder) => binder.skip_binder(), + &PredicateKind::Atom(atom) => { + debug_assert!(!atom.has_escaping_bound_vars()); + atom + } + } + } + + /// Returns the inner `PredicateAtom`. + /// + /// Note that this method does not check if the predicate has unbound variables. + /// + /// Rebinding the returned atom can causes the previously bound variables + /// to end up at the wrong binding level. + pub fn skip_binders_unchecked(self) -> PredicateAtom<'tcx> { + match self.kind() { + &PredicateKind::ForAll(binder) => binder.skip_binder(), + &PredicateKind::Atom(atom) => atom, + } + } + + /// Allows using a `Binder<PredicateAtom<'tcx>>` even if the given predicate previously + /// contained unbound variables by shifting these variables outwards. + pub fn bound_atom(self, tcx: TyCtxt<'tcx>) -> Binder<PredicateAtom<'tcx>> { + match self.kind() { + &PredicateKind::ForAll(binder) => binder, + &PredicateKind::Atom(atom) => Binder::wrap_nonbinding(tcx, atom), + } + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let PredicateInner { + ref kind, + + // The other fields just provide fast access to information that is + // also contained in `kind`, so no need to hash them. + flags: _, + outer_exclusive_binder: _, + } = self.inner; + + kind.hash_stable(hcx, hasher); + } +} + +#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub enum PredicateKind<'tcx> { + /// `for<'a>: ...` + ForAll(Binder<PredicateAtom<'tcx>>), + Atom(PredicateAtom<'tcx>), +} + +#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub enum PredicateAtom<'tcx> { + /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be + /// the `Self` type of the trait reference and `A`, `B`, and `C` + /// would be the type parameters. + /// + /// A trait predicate will have `Constness::Const` if it originates + /// from a bound on a `const fn` without the `?const` opt-out (e.g., + /// `const fn foobar<Foo: Bar>() {}`). + Trait(TraitPredicate<'tcx>, Constness), + + /// `where 'a: 'b` + RegionOutlives(RegionOutlivesPredicate<'tcx>), + + /// `where T: 'a` + TypeOutlives(TypeOutlivesPredicate<'tcx>), + + /// `where <T as TraitRef>::Name == X`, approximately. + /// See the `ProjectionPredicate` struct for details. + Projection(ProjectionPredicate<'tcx>), + + /// No syntax: `T` well-formed. + WellFormed(GenericArg<'tcx>), + + /// Trait must be object-safe. + ObjectSafe(DefId), + + /// No direct syntax. May be thought of as `where T: FnFoo<...>` + /// for some substitutions `...` and `T` being a closure type. + /// Satisfied (or refuted) once we know the closure's kind. + ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind), + + /// `T1 <: T2` + Subtype(SubtypePredicate<'tcx>), + + /// Constant initializer must evaluate successfully. + ConstEvaluatable(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>), + + /// Constants must be equal. The first component is the const that is expected. + ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>), +} + +impl<'tcx> PredicateAtom<'tcx> { + /// Wraps `self` with the given qualifier if this predicate has any unbound variables. + pub fn potentially_quantified( + self, + tcx: TyCtxt<'tcx>, + qualifier: impl FnOnce(Binder<PredicateAtom<'tcx>>) -> PredicateKind<'tcx>, + ) -> Predicate<'tcx> { + if self.has_escaping_bound_vars() { + qualifier(Binder::bind(self)) + } else { + PredicateKind::Atom(self) + } + .to_predicate(tcx) + } +} + +/// The crate outlives map is computed during typeck and contains the +/// outlives of every item in the local crate. You should not use it +/// directly, because to do so will make your pass dependent on the +/// HIR of every item in the local crate. Instead, use +/// `tcx.inferred_outlives_of()` to get the outlives for a *particular* +/// item. +#[derive(HashStable)] +pub struct CratePredicatesMap<'tcx> { + /// For each struct with outlive bounds, maps to a vector of the + /// predicate of its outlive bounds. If an item has no outlives + /// bounds, it will have no entry. + pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>, +} + +impl<'tcx> Predicate<'tcx> { + /// Performs a substitution suitable for going from a + /// poly-trait-ref to supertraits that must hold if that + /// poly-trait-ref holds. This is slightly different from a normal + /// substitution in terms of what happens with bound regions. See + /// lengthy comment below for details. + pub fn subst_supertrait( + self, + tcx: TyCtxt<'tcx>, + trait_ref: &ty::PolyTraitRef<'tcx>, + ) -> Predicate<'tcx> { + // The interaction between HRTB and supertraits is not entirely + // obvious. Let me walk you (and myself) through an example. + // + // Let's start with an easy case. Consider two traits: + // + // trait Foo<'a>: Bar<'a,'a> { } + // trait Bar<'b,'c> { } + // + // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then + // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we + // knew that `Foo<'x>` (for any 'x) then we also know that + // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from + // normal substitution. + // + // In terms of why this is sound, the idea is that whenever there + // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>` + // holds. So if there is an impl of `T:Foo<'a>` that applies to + // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all + // `'a`. + // + // Another example to be careful of is this: + // + // trait Foo1<'a>: for<'b> Bar1<'a,'b> { } + // trait Bar1<'b,'c> { } + // + // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know? + // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The + // reason is similar to the previous example: any impl of + // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So + // basically we would want to collapse the bound lifetimes from + // the input (`trait_ref`) and the supertraits. + // + // To achieve this in practice is fairly straightforward. Let's + // consider the more complicated scenario: + // + // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x` + // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`, + // where both `'x` and `'b` would have a DB index of 1. + // The substitution from the input trait-ref is therefore going to be + // `'a => 'x` (where `'x` has a DB index of 1). + // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an + // early-bound parameter and `'b' is a late-bound parameter with a + // DB index of 1. + // - If we replace `'a` with `'x` from the input, it too will have + // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>` + // just as we wanted. + // + // There is only one catch. If we just apply the substitution `'a + // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will + // adjust the DB index because we substituting into a binder (it + // tries to be so smart...) resulting in `for<'x> for<'b> + // Bar1<'x,'b>` (we have no syntax for this, so use your + // imagination). Basically the 'x will have DB index of 2 and 'b + // will have DB index of 1. Not quite what we want. So we apply + // the substitution to the *contents* of the trait reference, + // rather than the trait reference itself (put another way, the + // substitution code expects equal binding levels in the values + // from the substitution and the value being substituted into, and + // this trick achieves that). + let substs = trait_ref.skip_binder().substs; + let pred = self.skip_binders(); + let new = pred.subst(tcx, substs); + if new != pred { new.potentially_quantified(tcx, PredicateKind::ForAll) } else { self } + } +} + +#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct TraitPredicate<'tcx> { + pub trait_ref: TraitRef<'tcx>, +} + +pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>; + +impl<'tcx> TraitPredicate<'tcx> { + pub fn def_id(self) -> DefId { + self.trait_ref.def_id + } + + pub fn self_ty(self) -> Ty<'tcx> { + self.trait_ref.self_ty() + } +} + +impl<'tcx> PolyTraitPredicate<'tcx> { + pub fn def_id(self) -> DefId { + // Ok to skip binder since trait `DefId` does not care about regions. + self.skip_binder().def_id() + } +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B` +pub type PolyOutlivesPredicate<A, B> = ty::Binder<OutlivesPredicate<A, B>>; +pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>; +pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>; +pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>; +pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>; + +#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct SubtypePredicate<'tcx> { + pub a_is_expected: bool, + pub a: Ty<'tcx>, + pub b: Ty<'tcx>, +} +pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>; + +/// This kind of predicate has no *direct* correspondent in the +/// syntax, but it roughly corresponds to the syntactic forms: +/// +/// 1. `T: TraitRef<..., Item = Type>` +/// 2. `<T as TraitRef<...>>::Item == Type` (NYI) +/// +/// In particular, form #1 is "desugared" to the combination of a +/// normal trait predicate (`T: TraitRef<...>`) and one of these +/// predicates. Form #2 is a broader form in that it also permits +/// equality between arbitrary types. Processing an instance of +/// Form #2 eventually yields one of these `ProjectionPredicate` +/// instances to normalize the LHS. +#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct ProjectionPredicate<'tcx> { + pub projection_ty: ProjectionTy<'tcx>, + pub ty: Ty<'tcx>, +} + +pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>; + +impl<'tcx> PolyProjectionPredicate<'tcx> { + /// Returns the `DefId` of the associated item being projected. + pub fn item_def_id(&self) -> DefId { + self.skip_binder().projection_ty.item_def_id + } + + #[inline] + pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> { + // Note: unlike with `TraitRef::to_poly_trait_ref()`, + // `self.0.trait_ref` is permitted to have escaping regions. + // This is because here `self` has a `Binder` and so does our + // return value, so we are preserving the number of binding + // levels. + self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx)) + } + + pub fn ty(&self) -> Binder<Ty<'tcx>> { + self.map_bound(|predicate| predicate.ty) + } + + /// The `DefId` of the `TraitItem` for the associated type. + /// + /// Note that this is not the `DefId` of the `TraitRef` containing this + /// associated type, which is in `tcx.associated_item(projection_def_id()).container`. + pub fn projection_def_id(&self) -> DefId { + // Ok to skip binder since trait `DefId` does not care about regions. + self.skip_binder().projection_ty.item_def_id + } +} + +pub trait ToPolyTraitRef<'tcx> { + fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>; +} + +impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> { + fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> { + ty::Binder::dummy(*self) + } +} + +impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> { + fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> { + self.map_bound_ref(|trait_pred| trait_pred.trait_ref) + } +} + +pub trait ToPredicate<'tcx> { + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>; +} + +impl ToPredicate<'tcx> for PredicateKind<'tcx> { + #[inline(always)] + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { + tcx.mk_predicate(self) + } +} + +impl ToPredicate<'tcx> for PredicateAtom<'tcx> { + #[inline(always)] + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { + debug_assert!(!self.has_escaping_bound_vars(), "escaping bound vars for {:?}", self); + tcx.mk_predicate(PredicateKind::Atom(self)) + } +} + +impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> { + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { + PredicateAtom::Trait(ty::TraitPredicate { trait_ref: self.value }, self.constness) + .to_predicate(tcx) + } +} + +impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> { + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { + ConstnessAnd { + value: self.value.map_bound(|trait_ref| ty::TraitPredicate { trait_ref }), + constness: self.constness, + } + .to_predicate(tcx) + } +} + +impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitPredicate<'tcx>> { + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { + PredicateAtom::Trait(self.value.skip_binder(), self.constness) + .potentially_quantified(tcx, PredicateKind::ForAll) + } +} + +impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> { + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { + PredicateAtom::RegionOutlives(self.skip_binder()) + .potentially_quantified(tcx, PredicateKind::ForAll) + } +} + +impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> { + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { + PredicateAtom::TypeOutlives(self.skip_binder()) + .potentially_quantified(tcx, PredicateKind::ForAll) + } +} + +impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> { + fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { + PredicateAtom::Projection(self.skip_binder()) + .potentially_quantified(tcx, PredicateKind::ForAll) + } +} + +impl<'tcx> Predicate<'tcx> { + pub fn to_opt_poly_trait_ref(self) -> Option<PolyTraitRef<'tcx>> { + match self.skip_binders() { + PredicateAtom::Trait(t, _) => Some(ty::Binder::bind(t.trait_ref)), + PredicateAtom::Projection(..) + | PredicateAtom::Subtype(..) + | PredicateAtom::RegionOutlives(..) + | PredicateAtom::WellFormed(..) + | PredicateAtom::ObjectSafe(..) + | PredicateAtom::ClosureKind(..) + | PredicateAtom::TypeOutlives(..) + | PredicateAtom::ConstEvaluatable(..) + | PredicateAtom::ConstEquate(..) => None, + } + } + + pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> { + match self.skip_binders() { + PredicateAtom::TypeOutlives(data) => Some(ty::Binder::bind(data)), + PredicateAtom::Trait(..) + | PredicateAtom::Projection(..) + | PredicateAtom::Subtype(..) + | PredicateAtom::RegionOutlives(..) + | PredicateAtom::WellFormed(..) + | PredicateAtom::ObjectSafe(..) + | PredicateAtom::ClosureKind(..) + | PredicateAtom::ConstEvaluatable(..) + | PredicateAtom::ConstEquate(..) => None, + } + } +} + +/// Represents the bounds declared on a particular set of type +/// parameters. Should eventually be generalized into a flag list of +/// where-clauses. You can obtain a `InstantiatedPredicates` list from a +/// `GenericPredicates` by using the `instantiate` method. Note that this method +/// reflects an important semantic invariant of `InstantiatedPredicates`: while +/// the `GenericPredicates` are expressed in terms of the bound type +/// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance +/// represented a set of bounds for some particular instantiation, +/// meaning that the generic parameters have been substituted with +/// their values. +/// +/// Example: +/// +/// struct Foo<T, U: Bar<T>> { ... } +/// +/// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like +/// `[[], [U:Bar<T>]]`. Now if there were some particular reference +/// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[], +/// [usize:Bar<isize>]]`. +#[derive(Clone, Debug, TypeFoldable)] +pub struct InstantiatedPredicates<'tcx> { + pub predicates: Vec<Predicate<'tcx>>, + pub spans: Vec<Span>, +} + +impl<'tcx> InstantiatedPredicates<'tcx> { + pub fn empty() -> InstantiatedPredicates<'tcx> { + InstantiatedPredicates { predicates: vec![], spans: vec![] } + } + + pub fn is_empty(&self) -> bool { + self.predicates.is_empty() + } +} + +rustc_index::newtype_index! { + /// "Universes" are used during type- and trait-checking in the + /// presence of `for<..>` binders to control what sets of names are + /// visible. Universes are arranged into a tree: the root universe + /// contains names that are always visible. Each child then adds a new + /// set of names that are visible, in addition to those of its parent. + /// We say that the child universe "extends" the parent universe with + /// new names. + /// + /// To make this more concrete, consider this program: + /// + /// ``` + /// struct Foo { } + /// fn bar<T>(x: T) { + /// let y: for<'a> fn(&'a u8, Foo) = ...; + /// } + /// ``` + /// + /// The struct name `Foo` is in the root universe U0. But the type + /// parameter `T`, introduced on `bar`, is in an extended universe U1 + /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside + /// of `bar`, we cannot name `T`. Then, within the type of `y`, the + /// region `'a` is in a universe U2 that extends U1, because we can + /// name it inside the fn type but not outside. + /// + /// Universes are used to do type- and trait-checking around these + /// "forall" binders (also called **universal quantification**). The + /// idea is that when, in the body of `bar`, we refer to `T` as a + /// type, we aren't referring to any type in particular, but rather a + /// kind of "fresh" type that is distinct from all other types we have + /// actually declared. This is called a **placeholder** type, and we + /// use universes to talk about this. In other words, a type name in + /// universe 0 always corresponds to some "ground" type that the user + /// declared, but a type name in a non-zero universe is a placeholder + /// type -- an idealized representative of "types in general" that we + /// use for checking generic functions. + pub struct UniverseIndex { + derive [HashStable] + DEBUG_FORMAT = "U{}", + } +} + +impl UniverseIndex { + pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0); + + /// Returns the "next" universe index in order -- this new index + /// is considered to extend all previous universes. This + /// corresponds to entering a `forall` quantifier. So, for + /// example, suppose we have this type in universe `U`: + /// + /// ``` + /// for<'a> fn(&'a u32) + /// ``` + /// + /// Once we "enter" into this `for<'a>` quantifier, we are in a + /// new universe that extends `U` -- in this new universe, we can + /// name the region `'a`, but that region was not nameable from + /// `U` because it was not in scope there. + pub fn next_universe(self) -> UniverseIndex { + UniverseIndex::from_u32(self.private.checked_add(1).unwrap()) + } + + /// Returns `true` if `self` can name a name from `other` -- in other words, + /// if the set of names in `self` is a superset of those in + /// `other` (`self >= other`). + pub fn can_name(self, other: UniverseIndex) -> bool { + self.private >= other.private + } + + /// Returns `true` if `self` cannot name some names from `other` -- in other + /// words, if the set of names in `self` is a strict subset of + /// those in `other` (`self < other`). + pub fn cannot_name(self, other: UniverseIndex) -> bool { + self.private < other.private + } +} + +/// The "placeholder index" fully defines a placeholder region. +/// Placeholder regions are identified by both a **universe** as well +/// as a "bound-region" within that universe. The `bound_region` is +/// basically a name -- distinct bound regions within the same +/// universe are just two regions with an unknown relationship to one +/// another. +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)] +pub struct Placeholder<T> { + pub universe: UniverseIndex, + pub name: T, +} + +impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T> +where + T: HashStable<StableHashingContext<'a>>, +{ + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + self.universe.hash_stable(hcx, hasher); + self.name.hash_stable(hcx, hasher); + } +} + +pub type PlaceholderRegion = Placeholder<BoundRegion>; + +pub type PlaceholderType = Placeholder<BoundVar>; + +pub type PlaceholderConst = Placeholder<BoundVar>; + +/// A `DefId` which is potentially bundled with its corresponding generic parameter +/// in case `did` is a const argument. +/// +/// This is used to prevent cycle errors during typeck +/// as `type_of(const_arg)` depends on `typeck(owning_body)` +/// which once again requires the type of its generic arguments. +/// +/// Luckily we only need to deal with const arguments once we +/// know their corresponding parameters. We (ab)use this by +/// calling `type_of(param_did)` for these arguments. +/// +/// ```rust +/// #![feature(const_generics)] +/// +/// struct A; +/// impl A { +/// fn foo<const N: usize>(&self) -> usize { N } +/// } +/// struct B; +/// impl B { +/// fn foo<const N: u8>(&self) -> usize { 42 } +/// } +/// +/// fn main() { +/// let a = A; +/// a.foo::<7>(); +/// } +/// ``` +#[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)] +#[derive(PartialEq, Eq, PartialOrd, Ord)] +#[derive(Hash, HashStable)] +pub struct WithOptConstParam<T> { + pub did: T, + /// The `DefId` of the corresponding generic paramter in case `did` is + /// a const argument. + /// + /// Note that even if `did` is a const argument, this may still be `None`. + /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)` + /// to potentially update `param_did` in case it `None`. + pub const_param_did: Option<DefId>, +} + +impl<T> WithOptConstParam<T> { + /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`. + #[inline(always)] + pub fn unknown(did: T) -> WithOptConstParam<T> { + WithOptConstParam { did, const_param_did: None } + } +} + +impl WithOptConstParam<LocalDefId> { + /// Returns `Some((did, param_did))` if `def_id` is a const argument, + /// `None` otherwise. + #[inline(always)] + pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> { + tcx.opt_const_param_of(did).map(|param_did| (did, param_did)) + } + + /// In case `self` is unknown but `self.did` is a const argument, this returns + /// a `WithOptConstParam` with the correct `const_param_did`. + #[inline(always)] + pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> { + if self.const_param_did.is_none() { + if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) { + return Some(WithOptConstParam { did: self.did, const_param_did }); + } + } + + None + } + + pub fn to_global(self) -> WithOptConstParam<DefId> { + WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did } + } + + pub fn def_id_for_type_of(self) -> DefId { + if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() } + } +} + +impl WithOptConstParam<DefId> { + pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> { + self.did + .as_local() + .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did }) + } + + pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> { + if let Some(param_did) = self.const_param_did { + if let Some(did) = self.did.as_local() { + return Some((did, param_did)); + } + } + + None + } + + pub fn expect_local(self) -> WithOptConstParam<LocalDefId> { + self.as_local().unwrap() + } + + pub fn is_local(self) -> bool { + self.did.is_local() + } + + pub fn def_id_for_type_of(self) -> DefId { + self.const_param_did.unwrap_or(self.did) + } +} + +/// When type checking, we use the `ParamEnv` to track +/// details about the set of where-clauses that are in scope at this +/// particular point. +#[derive(Copy, Clone, Hash, PartialEq, Eq)] +pub struct ParamEnv<'tcx> { + /// This packs both caller bounds and the reveal enum into one pointer. + /// + /// Caller bounds are `Obligation`s that the caller must satisfy. This is + /// basically the set of bounds on the in-scope type parameters, translated + /// into `Obligation`s, and elaborated and normalized. + /// + /// Use the `caller_bounds()` method to access. + /// + /// Typically, this is `Reveal::UserFacing`, but during codegen we + /// want `Reveal::All`. + /// + /// Note: This is packed, use the reveal() method to access it. + packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, traits::Reveal, true>, + + /// If this `ParamEnv` comes from a call to `tcx.param_env(def_id)`, + /// register that `def_id` (useful for transitioning to the chalk trait + /// solver). + pub def_id: Option<DefId>, +} + +unsafe impl rustc_data_structures::tagged_ptr::Tag for traits::Reveal { + const BITS: usize = 1; + fn into_usize(self) -> usize { + match self { + traits::Reveal::UserFacing => 0, + traits::Reveal::All => 1, + } + } + unsafe fn from_usize(ptr: usize) -> Self { + match ptr { + 0 => traits::Reveal::UserFacing, + 1 => traits::Reveal::All, + _ => std::hint::unreachable_unchecked(), + } + } +} + +impl<'tcx> fmt::Debug for ParamEnv<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("ParamEnv") + .field("caller_bounds", &self.caller_bounds()) + .field("reveal", &self.reveal()) + .field("def_id", &self.def_id) + .finish() + } +} + +impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + self.caller_bounds().hash_stable(hcx, hasher); + self.reveal().hash_stable(hcx, hasher); + self.def_id.hash_stable(hcx, hasher); + } +} + +impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> { + fn super_fold_with<F: ty::fold::TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + ParamEnv::new( + self.caller_bounds().fold_with(folder), + self.reveal().fold_with(folder), + self.def_id.fold_with(folder), + ) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.caller_bounds().visit_with(visitor) + || self.reveal().visit_with(visitor) + || self.def_id.visit_with(visitor) + } +} + +impl<'tcx> ParamEnv<'tcx> { + /// Construct a trait environment suitable for contexts where + /// there are no where-clauses in scope. Hidden types (like `impl + /// Trait`) are left hidden, so this is suitable for ordinary + /// type-checking. + #[inline] + pub fn empty() -> Self { + Self::new(List::empty(), Reveal::UserFacing, None) + } + + #[inline] + pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> { + self.packed.pointer() + } + + #[inline] + pub fn reveal(self) -> traits::Reveal { + self.packed.tag() + } + + /// Construct a trait environment with no where-clauses in scope + /// where the values of all `impl Trait` and other hidden types + /// are revealed. This is suitable for monomorphized, post-typeck + /// environments like codegen or doing optimizations. + /// + /// N.B., if you want to have predicates in scope, use `ParamEnv::new`, + /// or invoke `param_env.with_reveal_all()`. + #[inline] + pub fn reveal_all() -> Self { + Self::new(List::empty(), Reveal::All, None) + } + + /// Construct a trait environment with the given set of predicates. + #[inline] + pub fn new( + caller_bounds: &'tcx List<Predicate<'tcx>>, + reveal: Reveal, + def_id: Option<DefId>, + ) -> Self { + ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal), def_id } + } + + pub fn with_user_facing(mut self) -> Self { + self.packed.set_tag(Reveal::UserFacing); + self + } + + /// Returns a new parameter environment with the same clauses, but + /// which "reveals" the true results of projections in all cases + /// (even for associated types that are specializable). This is + /// the desired behavior during codegen and certain other special + /// contexts; normally though we want to use `Reveal::UserFacing`, + /// which is the default. + /// All opaque types in the caller_bounds of the `ParamEnv` + /// will be normalized to their underlying types. + /// See PR #65989 and issue #65918 for more details + pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self { + if self.packed.tag() == traits::Reveal::All { + return self; + } + + ParamEnv::new(tcx.normalize_opaque_types(self.caller_bounds()), Reveal::All, self.def_id) + } + + /// Returns this same environment but with no caller bounds. + pub fn without_caller_bounds(self) -> Self { + Self::new(List::empty(), self.reveal(), self.def_id) + } + + /// Creates a suitable environment in which to perform trait + /// queries on the given value. When type-checking, this is simply + /// the pair of the environment plus value. But when reveal is set to + /// All, then if `value` does not reference any type parameters, we will + /// pair it with the empty environment. This improves caching and is generally + /// invisible. + /// + /// N.B., we preserve the environment when type-checking because it + /// is possible for the user to have wacky where-clauses like + /// `where Box<u32>: Copy`, which are clearly never + /// satisfiable. We generally want to behave as if they were true, + /// although the surrounding function is never reachable. + pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> { + match self.reveal() { + Reveal::UserFacing => ParamEnvAnd { param_env: self, value }, + + Reveal::All => { + if value.is_global() { + ParamEnvAnd { param_env: self.without_caller_bounds(), value } + } else { + ParamEnvAnd { param_env: self, value } + } + } + } + } +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)] +pub struct ConstnessAnd<T> { + pub constness: Constness, + pub value: T, +} + +// FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that +// the constness of trait bounds is being propagated correctly. +pub trait WithConstness: Sized { + #[inline] + fn with_constness(self, constness: Constness) -> ConstnessAnd<Self> { + ConstnessAnd { constness, value: self } + } + + #[inline] + fn with_const(self) -> ConstnessAnd<Self> { + self.with_constness(Constness::Const) + } + + #[inline] + fn without_const(self) -> ConstnessAnd<Self> { + self.with_constness(Constness::NotConst) + } +} + +impl<T> WithConstness for T {} + +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)] +pub struct ParamEnvAnd<'tcx, T> { + pub param_env: ParamEnv<'tcx>, + pub value: T, +} + +impl<'tcx, T> ParamEnvAnd<'tcx, T> { + pub fn into_parts(self) -> (ParamEnv<'tcx>, T) { + (self.param_env, self.value) + } +} + +impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T> +where + T: HashStable<StableHashingContext<'a>>, +{ + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let ParamEnvAnd { ref param_env, ref value } = *self; + + param_env.hash_stable(hcx, hasher); + value.hash_stable(hcx, hasher); + } +} + +#[derive(Copy, Clone, Debug, HashStable)] +pub struct Destructor { + /// The `DefId` of the destructor method + pub did: DefId, +} + +bitflags! { + #[derive(HashStable)] + pub struct AdtFlags: u32 { + const NO_ADT_FLAGS = 0; + /// Indicates whether the ADT is an enum. + const IS_ENUM = 1 << 0; + /// Indicates whether the ADT is a union. + const IS_UNION = 1 << 1; + /// Indicates whether the ADT is a struct. + const IS_STRUCT = 1 << 2; + /// Indicates whether the ADT is a struct and has a constructor. + const HAS_CTOR = 1 << 3; + /// Indicates whether the type is `PhantomData`. + const IS_PHANTOM_DATA = 1 << 4; + /// Indicates whether the type has a `#[fundamental]` attribute. + const IS_FUNDAMENTAL = 1 << 5; + /// Indicates whether the type is `Box`. + const IS_BOX = 1 << 6; + /// Indicates whether the type is `ManuallyDrop`. + const IS_MANUALLY_DROP = 1 << 7; + /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`. + /// (i.e., this flag is never set unless this ADT is an enum). + const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8; + } +} + +bitflags! { + #[derive(HashStable)] + pub struct VariantFlags: u32 { + const NO_VARIANT_FLAGS = 0; + /// Indicates whether the field list of this variant is `#[non_exhaustive]`. + const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0; + /// Indicates whether this variant was obtained as part of recovering from + /// a syntactic error. May be incomplete or bogus. + const IS_RECOVERED = 1 << 1; + } +} + +/// Definition of a variant -- a struct's fields or a enum variant. +#[derive(Debug, HashStable)] +pub struct VariantDef { + /// `DefId` that identifies the variant itself. + /// If this variant belongs to a struct or union, then this is a copy of its `DefId`. + pub def_id: DefId, + /// `DefId` that identifies the variant's constructor. + /// If this variant is a struct variant, then this is `None`. + pub ctor_def_id: Option<DefId>, + /// Variant or struct name. + #[stable_hasher(project(name))] + pub ident: Ident, + /// Discriminant of this variant. + pub discr: VariantDiscr, + /// Fields of this variant. + pub fields: Vec<FieldDef>, + /// Type of constructor of variant. + pub ctor_kind: CtorKind, + /// Flags of the variant (e.g. is field list non-exhaustive)? + flags: VariantFlags, +} + +impl<'tcx> VariantDef { + /// Creates a new `VariantDef`. + /// + /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef` + /// represents an enum variant). + /// + /// `ctor_did` is the `DefId` that identifies the constructor of unit or + /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`. + /// + /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that + /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having + /// to go through the redirect of checking the ctor's attributes - but compiling a small crate + /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any + /// built-in trait), and we do not want to load attributes twice. + /// + /// If someone speeds up attribute loading to not be a performance concern, they can + /// remove this hack and use the constructor `DefId` everywhere. + pub fn new( + ident: Ident, + variant_did: Option<DefId>, + ctor_def_id: Option<DefId>, + discr: VariantDiscr, + fields: Vec<FieldDef>, + ctor_kind: CtorKind, + adt_kind: AdtKind, + parent_did: DefId, + recovered: bool, + is_field_list_non_exhaustive: bool, + ) -> Self { + debug!( + "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?}, + fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})", + ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did, + ); + + let mut flags = VariantFlags::NO_VARIANT_FLAGS; + if is_field_list_non_exhaustive { + flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE; + } + + if recovered { + flags |= VariantFlags::IS_RECOVERED; + } + + VariantDef { + def_id: variant_did.unwrap_or(parent_did), + ctor_def_id, + ident, + discr, + fields, + ctor_kind, + flags, + } + } + + /// Is this field list non-exhaustive? + #[inline] + pub fn is_field_list_non_exhaustive(&self) -> bool { + self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE) + } + + /// Was this variant obtained as part of recovering from a syntactic error? + #[inline] + pub fn is_recovered(&self) -> bool { + self.flags.intersects(VariantFlags::IS_RECOVERED) + } + + /// `repr(transparent)` structs can have a single non-ZST field, this function returns that + /// field. + pub fn transparent_newtype_field(&self, tcx: TyCtxt<'tcx>) -> Option<&FieldDef> { + for field in &self.fields { + let field_ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, self.def_id)); + if !field_ty.is_zst(tcx, self.def_id) { + return Some(field); + } + } + + None + } +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] +pub enum VariantDiscr { + /// Explicit value for this variant, i.e., `X = 123`. + /// The `DefId` corresponds to the embedded constant. + Explicit(DefId), + + /// The previous variant's discriminant plus one. + /// For efficiency reasons, the distance from the + /// last `Explicit` discriminant is being stored, + /// or `0` for the first variant, if it has none. + Relative(u32), +} + +#[derive(Debug, HashStable)] +pub struct FieldDef { + pub did: DefId, + #[stable_hasher(project(name))] + pub ident: Ident, + pub vis: Visibility, +} + +/// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`. +/// +/// These are all interned (by `alloc_adt_def`) into the global arena. +/// +/// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt]. +/// This is slightly wrong because `union`s are not ADTs. +/// Moreover, Rust only allows recursive data types through indirection. +/// +/// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type +pub struct AdtDef { + /// The `DefId` of the struct, enum or union item. + pub did: DefId, + /// Variants of the ADT. If this is a struct or union, then there will be a single variant. + pub variants: IndexVec<VariantIdx, VariantDef>, + /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?). + flags: AdtFlags, + /// Repr options provided by the user. + pub repr: ReprOptions, +} + +impl PartialOrd for AdtDef { + fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> { + Some(self.cmp(&other)) + } +} + +/// There should be only one AdtDef for each `did`, therefore +/// it is fine to implement `Ord` only based on `did`. +impl Ord for AdtDef { + fn cmp(&self, other: &AdtDef) -> Ordering { + self.did.cmp(&other.did) + } +} + +impl PartialEq for AdtDef { + // `AdtDef`s are always interned, and this is part of `TyS` equality. + #[inline] + fn eq(&self, other: &Self) -> bool { + ptr::eq(self, other) + } +} + +impl Eq for AdtDef {} + +impl Hash for AdtDef { + #[inline] + fn hash<H: Hasher>(&self, s: &mut H) { + (self as *const AdtDef).hash(s) + } +} + +impl<S: Encoder> Encodable<S> for AdtDef { + fn encode(&self, s: &mut S) -> Result<(), S::Error> { + self.did.encode(s) + } +} + +impl<'a> HashStable<StableHashingContext<'a>> for AdtDef { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + thread_local! { + static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default(); + } + + let hash: Fingerprint = CACHE.with(|cache| { + let addr = self as *const AdtDef as usize; + *cache.borrow_mut().entry(addr).or_insert_with(|| { + let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self; + + let mut hasher = StableHasher::new(); + did.hash_stable(hcx, &mut hasher); + variants.hash_stable(hcx, &mut hasher); + flags.hash_stable(hcx, &mut hasher); + repr.hash_stable(hcx, &mut hasher); + + hasher.finish() + }) + }); + + hash.hash_stable(hcx, hasher); + } +} + +#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)] +pub enum AdtKind { + Struct, + Union, + Enum, +} + +impl Into<DataTypeKind> for AdtKind { + fn into(self) -> DataTypeKind { + match self { + AdtKind::Struct => DataTypeKind::Struct, + AdtKind::Union => DataTypeKind::Union, + AdtKind::Enum => DataTypeKind::Enum, + } + } +} + +bitflags! { + #[derive(TyEncodable, TyDecodable, Default, HashStable)] + pub struct ReprFlags: u8 { + const IS_C = 1 << 0; + const IS_SIMD = 1 << 1; + const IS_TRANSPARENT = 1 << 2; + // Internal only for now. If true, don't reorder fields. + const IS_LINEAR = 1 << 3; + // If true, don't expose any niche to type's context. + const HIDE_NICHE = 1 << 4; + // Any of these flags being set prevent field reordering optimisation. + const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits | + ReprFlags::IS_SIMD.bits | + ReprFlags::IS_LINEAR.bits; + } +} + +/// Represents the repr options provided by the user, +#[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)] +pub struct ReprOptions { + pub int: Option<attr::IntType>, + pub align: Option<Align>, + pub pack: Option<Align>, + pub flags: ReprFlags, +} + +impl ReprOptions { + pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions { + let mut flags = ReprFlags::empty(); + let mut size = None; + let mut max_align: Option<Align> = None; + let mut min_pack: Option<Align> = None; + for attr in tcx.get_attrs(did).iter() { + for r in attr::find_repr_attrs(&tcx.sess, attr) { + flags.insert(match r { + attr::ReprC => ReprFlags::IS_C, + attr::ReprPacked(pack) => { + let pack = Align::from_bytes(pack as u64).unwrap(); + min_pack = Some(if let Some(min_pack) = min_pack { + min_pack.min(pack) + } else { + pack + }); + ReprFlags::empty() + } + attr::ReprTransparent => ReprFlags::IS_TRANSPARENT, + attr::ReprNoNiche => ReprFlags::HIDE_NICHE, + attr::ReprSimd => ReprFlags::IS_SIMD, + attr::ReprInt(i) => { + size = Some(i); + ReprFlags::empty() + } + attr::ReprAlign(align) => { + max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap())); + ReprFlags::empty() + } + }); + } + } + + // This is here instead of layout because the choice must make it into metadata. + if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) { + flags.insert(ReprFlags::IS_LINEAR); + } + ReprOptions { int: size, align: max_align, pack: min_pack, flags } + } + + #[inline] + pub fn simd(&self) -> bool { + self.flags.contains(ReprFlags::IS_SIMD) + } + #[inline] + pub fn c(&self) -> bool { + self.flags.contains(ReprFlags::IS_C) + } + #[inline] + pub fn packed(&self) -> bool { + self.pack.is_some() + } + #[inline] + pub fn transparent(&self) -> bool { + self.flags.contains(ReprFlags::IS_TRANSPARENT) + } + #[inline] + pub fn linear(&self) -> bool { + self.flags.contains(ReprFlags::IS_LINEAR) + } + #[inline] + pub fn hide_niche(&self) -> bool { + self.flags.contains(ReprFlags::HIDE_NICHE) + } + + /// Returns the discriminant type, given these `repr` options. + /// This must only be called on enums! + pub fn discr_type(&self) -> attr::IntType { + self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize)) + } + + /// Returns `true` if this `#[repr()]` should inhabit "smart enum + /// layout" optimizations, such as representing `Foo<&T>` as a + /// single pointer. + pub fn inhibit_enum_layout_opt(&self) -> bool { + self.c() || self.int.is_some() + } + + /// Returns `true` if this `#[repr()]` should inhibit struct field reordering + /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`. + pub fn inhibit_struct_field_reordering_opt(&self) -> bool { + if let Some(pack) = self.pack { + if pack.bytes() == 1 { + return true; + } + } + self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some() + } + + /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations. + pub fn inhibit_union_abi_opt(&self) -> bool { + self.c() + } +} + +impl<'tcx> AdtDef { + /// Creates a new `AdtDef`. + fn new( + tcx: TyCtxt<'_>, + did: DefId, + kind: AdtKind, + variants: IndexVec<VariantIdx, VariantDef>, + repr: ReprOptions, + ) -> Self { + debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr); + let mut flags = AdtFlags::NO_ADT_FLAGS; + + if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) { + debug!("found non-exhaustive variant list for {:?}", did); + flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE; + } + + flags |= match kind { + AdtKind::Enum => AdtFlags::IS_ENUM, + AdtKind::Union => AdtFlags::IS_UNION, + AdtKind::Struct => AdtFlags::IS_STRUCT, + }; + + if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() { + flags |= AdtFlags::HAS_CTOR; + } + + let attrs = tcx.get_attrs(did); + if tcx.sess.contains_name(&attrs, sym::fundamental) { + flags |= AdtFlags::IS_FUNDAMENTAL; + } + if Some(did) == tcx.lang_items().phantom_data() { + flags |= AdtFlags::IS_PHANTOM_DATA; + } + if Some(did) == tcx.lang_items().owned_box() { + flags |= AdtFlags::IS_BOX; + } + if Some(did) == tcx.lang_items().manually_drop() { + flags |= AdtFlags::IS_MANUALLY_DROP; + } + + AdtDef { did, variants, flags, repr } + } + + /// Returns `true` if this is a struct. + #[inline] + pub fn is_struct(&self) -> bool { + self.flags.contains(AdtFlags::IS_STRUCT) + } + + /// Returns `true` if this is a union. + #[inline] + pub fn is_union(&self) -> bool { + self.flags.contains(AdtFlags::IS_UNION) + } + + /// Returns `true` if this is a enum. + #[inline] + pub fn is_enum(&self) -> bool { + self.flags.contains(AdtFlags::IS_ENUM) + } + + /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`. + #[inline] + pub fn is_variant_list_non_exhaustive(&self) -> bool { + self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE) + } + + /// Returns the kind of the ADT. + #[inline] + pub fn adt_kind(&self) -> AdtKind { + if self.is_enum() { + AdtKind::Enum + } else if self.is_union() { + AdtKind::Union + } else { + AdtKind::Struct + } + } + + /// Returns a description of this abstract data type. + pub fn descr(&self) -> &'static str { + match self.adt_kind() { + AdtKind::Struct => "struct", + AdtKind::Union => "union", + AdtKind::Enum => "enum", + } + } + + /// Returns a description of a variant of this abstract data type. + #[inline] + pub fn variant_descr(&self) -> &'static str { + match self.adt_kind() { + AdtKind::Struct => "struct", + AdtKind::Union => "union", + AdtKind::Enum => "variant", + } + } + + /// If this function returns `true`, it implies that `is_struct` must return `true`. + #[inline] + pub fn has_ctor(&self) -> bool { + self.flags.contains(AdtFlags::HAS_CTOR) + } + + /// Returns `true` if this type is `#[fundamental]` for the purposes + /// of coherence checking. + #[inline] + pub fn is_fundamental(&self) -> bool { + self.flags.contains(AdtFlags::IS_FUNDAMENTAL) + } + + /// Returns `true` if this is `PhantomData<T>`. + #[inline] + pub fn is_phantom_data(&self) -> bool { + self.flags.contains(AdtFlags::IS_PHANTOM_DATA) + } + + /// Returns `true` if this is Box<T>. + #[inline] + pub fn is_box(&self) -> bool { + self.flags.contains(AdtFlags::IS_BOX) + } + + /// Returns `true` if this is `ManuallyDrop<T>`. + #[inline] + pub fn is_manually_drop(&self) -> bool { + self.flags.contains(AdtFlags::IS_MANUALLY_DROP) + } + + /// Returns `true` if this type has a destructor. + pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool { + self.destructor(tcx).is_some() + } + + /// Asserts this is a struct or union and returns its unique variant. + pub fn non_enum_variant(&self) -> &VariantDef { + assert!(self.is_struct() || self.is_union()); + &self.variants[VariantIdx::new(0)] + } + + #[inline] + pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> { + tcx.predicates_of(self.did) + } + + /// Returns an iterator over all fields contained + /// by this ADT. + #[inline] + pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone { + self.variants.iter().flat_map(|v| v.fields.iter()) + } + + pub fn is_payloadfree(&self) -> bool { + !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty()) + } + + /// Return a `VariantDef` given a variant id. + pub fn variant_with_id(&self, vid: DefId) -> &VariantDef { + self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant") + } + + /// Return a `VariantDef` given a constructor id. + pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef { + self.variants + .iter() + .find(|v| v.ctor_def_id == Some(cid)) + .expect("variant_with_ctor_id: unknown variant") + } + + /// Return the index of `VariantDef` given a variant id. + pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx { + self.variants + .iter_enumerated() + .find(|(_, v)| v.def_id == vid) + .expect("variant_index_with_id: unknown variant") + .0 + } + + /// Return the index of `VariantDef` given a constructor id. + pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx { + self.variants + .iter_enumerated() + .find(|(_, v)| v.ctor_def_id == Some(cid)) + .expect("variant_index_with_ctor_id: unknown variant") + .0 + } + + pub fn variant_of_res(&self, res: Res) -> &VariantDef { + match res { + Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid), + Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid), + Res::Def(DefKind::Struct, _) + | Res::Def(DefKind::Union, _) + | Res::Def(DefKind::TyAlias, _) + | Res::Def(DefKind::AssocTy, _) + | Res::SelfTy(..) + | Res::SelfCtor(..) => self.non_enum_variant(), + _ => bug!("unexpected res {:?} in variant_of_res", res), + } + } + + #[inline] + pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> { + assert!(self.is_enum()); + let param_env = tcx.param_env(expr_did); + let repr_type = self.repr.discr_type(); + match tcx.const_eval_poly(expr_did) { + Ok(val) => { + let ty = repr_type.to_ty(tcx); + if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) { + trace!("discriminants: {} ({:?})", b, repr_type); + Some(Discr { val: b, ty }) + } else { + info!("invalid enum discriminant: {:#?}", val); + crate::mir::interpret::struct_error( + tcx.at(tcx.def_span(expr_did)), + "constant evaluation of enum discriminant resulted in non-integer", + ) + .emit(); + None + } + } + Err(err) => { + let msg = match err { + ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => { + "enum discriminant evaluation failed" + } + ErrorHandled::TooGeneric => "enum discriminant depends on generics", + }; + tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg); + None + } + } + } + + #[inline] + pub fn discriminants( + &'tcx self, + tcx: TyCtxt<'tcx>, + ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> { + assert!(self.is_enum()); + let repr_type = self.repr.discr_type(); + let initial = repr_type.initial_discriminant(tcx); + let mut prev_discr = None::<Discr<'tcx>>; + self.variants.iter_enumerated().map(move |(i, v)| { + let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx)); + if let VariantDiscr::Explicit(expr_did) = v.discr { + if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) { + discr = new_discr; + } + } + prev_discr = Some(discr); + + (i, discr) + }) + } + + #[inline] + pub fn variant_range(&self) -> Range<VariantIdx> { + VariantIdx::new(0)..VariantIdx::new(self.variants.len()) + } + + /// Computes the discriminant value used by a specific variant. + /// Unlike `discriminants`, this is (amortized) constant-time, + /// only doing at most one query for evaluating an explicit + /// discriminant (the last one before the requested variant), + /// assuming there are no constant-evaluation errors there. + #[inline] + pub fn discriminant_for_variant( + &self, + tcx: TyCtxt<'tcx>, + variant_index: VariantIdx, + ) -> Discr<'tcx> { + assert!(self.is_enum()); + let (val, offset) = self.discriminant_def_for_variant(variant_index); + let explicit_value = val + .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did)) + .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx)); + explicit_value.checked_add(tcx, offset as u128).0 + } + + /// Yields a `DefId` for the discriminant and an offset to add to it + /// Alternatively, if there is no explicit discriminant, returns the + /// inferred discriminant directly. + pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) { + assert!(!self.variants.is_empty()); + let mut explicit_index = variant_index.as_u32(); + let expr_did; + loop { + match self.variants[VariantIdx::from_u32(explicit_index)].discr { + ty::VariantDiscr::Relative(0) => { + expr_did = None; + break; + } + ty::VariantDiscr::Relative(distance) => { + explicit_index -= distance; + } + ty::VariantDiscr::Explicit(did) => { + expr_did = Some(did); + break; + } + } + } + (expr_did, variant_index.as_u32() - explicit_index) + } + + pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> { + tcx.adt_destructor(self.did) + } + + /// Returns a list of types such that `Self: Sized` if and only + /// if that type is `Sized`, or `TyErr` if this type is recursive. + /// + /// Oddly enough, checking that the sized-constraint is `Sized` is + /// actually more expressive than checking all members: + /// the `Sized` trait is inductive, so an associated type that references + /// `Self` would prevent its containing ADT from being `Sized`. + /// + /// Due to normalization being eager, this applies even if + /// the associated type is behind a pointer (e.g., issue #31299). + pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] { + tcx.adt_sized_constraint(self.did).0 + } +} + +impl<'tcx> FieldDef { + /// Returns the type of this field. The `subst` is typically obtained + /// via the second field of `TyKind::AdtDef`. + pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> { + tcx.type_of(self.did).subst(tcx, subst) + } +} + +/// Represents the various closure traits in the language. This +/// will determine the type of the environment (`self`, in the +/// desugaring) argument that the closure expects. +/// +/// You can get the environment type of a closure using +/// `tcx.closure_env_ty()`. +#[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub enum ClosureKind { + // Warning: Ordering is significant here! The ordering is chosen + // because the trait Fn is a subtrait of FnMut and so in turn, and + // hence we order it so that Fn < FnMut < FnOnce. + Fn, + FnMut, + FnOnce, +} + +impl<'tcx> ClosureKind { + // This is the initial value used when doing upvar inference. + pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn; + + pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId { + match *self { + ClosureKind::Fn => tcx.require_lang_item(LangItem::Fn, None), + ClosureKind::FnMut => tcx.require_lang_item(LangItem::FnMut, None), + ClosureKind::FnOnce => tcx.require_lang_item(LangItem::FnOnce, None), + } + } + + /// Returns `true` if this a type that impls this closure kind + /// must also implement `other`. + pub fn extends(self, other: ty::ClosureKind) -> bool { + match (self, other) { + (ClosureKind::Fn, ClosureKind::Fn) => true, + (ClosureKind::Fn, ClosureKind::FnMut) => true, + (ClosureKind::Fn, ClosureKind::FnOnce) => true, + (ClosureKind::FnMut, ClosureKind::FnMut) => true, + (ClosureKind::FnMut, ClosureKind::FnOnce) => true, + (ClosureKind::FnOnce, ClosureKind::FnOnce) => true, + _ => false, + } + } + + /// Returns the representative scalar type for this closure kind. + /// See `TyS::to_opt_closure_kind` for more details. + pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + match self { + ty::ClosureKind::Fn => tcx.types.i8, + ty::ClosureKind::FnMut => tcx.types.i16, + ty::ClosureKind::FnOnce => tcx.types.i32, + } + } +} + +impl BorrowKind { + pub fn from_mutbl(m: hir::Mutability) -> BorrowKind { + match m { + hir::Mutability::Mut => MutBorrow, + hir::Mutability::Not => ImmBorrow, + } + } + + /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow + /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a + /// mutability that is stronger than necessary so that it at least *would permit* the borrow in + /// question. + pub fn to_mutbl_lossy(self) -> hir::Mutability { + match self { + MutBorrow => hir::Mutability::Mut, + ImmBorrow => hir::Mutability::Not, + + // We have no type corresponding to a unique imm borrow, so + // use `&mut`. It gives all the capabilities of an `&uniq` + // and hence is a safe "over approximation". + UniqueImmBorrow => hir::Mutability::Mut, + } + } + + pub fn to_user_str(&self) -> &'static str { + match *self { + MutBorrow => "mutable", + ImmBorrow => "immutable", + UniqueImmBorrow => "uniquely immutable", + } + } +} + +pub type Attributes<'tcx> = &'tcx [ast::Attribute]; + +#[derive(Debug, PartialEq, Eq)] +pub enum ImplOverlapKind { + /// These impls are always allowed to overlap. + Permitted { + /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait + marker: bool, + }, + /// These impls are allowed to overlap, but that raises + /// an issue #33140 future-compatibility warning. + /// + /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's + /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different. + /// + /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied + /// that difference, making what reduces to the following set of impls: + /// + /// ``` + /// trait Trait {} + /// impl Trait for dyn Send + Sync {} + /// impl Trait for dyn Sync + Send {} + /// ``` + /// + /// Obviously, once we made these types be identical, that code causes a coherence + /// error and a fairly big headache for us. However, luckily for us, the trait + /// `Trait` used in this case is basically a marker trait, and therefore having + /// overlapping impls for it is sound. + /// + /// To handle this, we basically regard the trait as a marker trait, with an additional + /// future-compatibility warning. To avoid accidentally "stabilizing" this feature, + /// it has the following restrictions: + /// + /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be + /// positive impls. + /// 2. The trait-ref of both impls must be equal. + /// 3. The trait-ref of both impls must be a trait object type consisting only of + /// marker traits. + /// 4. Neither of the impls can have any where-clauses. + /// + /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed. + Issue33140, +} + +impl<'tcx> TyCtxt<'tcx> { + pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> { + self.typeck(self.hir().body_owner_def_id(body)) + } + + /// Returns an iterator of the `DefId`s for all body-owners in this + /// crate. If you would prefer to iterate over the bodies + /// themselves, you can do `self.hir().krate().body_ids.iter()`. + pub fn body_owners(self) -> impl Iterator<Item = LocalDefId> + Captures<'tcx> + 'tcx { + self.hir() + .krate() + .body_ids + .iter() + .map(move |&body_id| self.hir().body_owner_def_id(body_id)) + } + + pub fn par_body_owners<F: Fn(LocalDefId) + sync::Sync + sync::Send>(self, f: F) { + par_iter(&self.hir().krate().body_ids) + .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id))); + } + + pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> { + self.associated_items(id) + .in_definition_order() + .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value()) + } + + pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> { + def_id + .as_local() + .and_then(|def_id| self.hir().get(self.hir().local_def_id_to_hir_id(def_id)).ident()) + } + + pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> { + let is_associated_item = if let Some(def_id) = def_id.as_local() { + match self.hir().get(self.hir().local_def_id_to_hir_id(def_id)) { + Node::TraitItem(_) | Node::ImplItem(_) => true, + _ => false, + } + } else { + match self.def_kind(def_id) { + DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy => true, + _ => false, + } + }; + + is_associated_item.then(|| self.associated_item(def_id)) + } + + pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize { + typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field") + } + + pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> { + variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id)) + } + + /// Returns `true` if the impls are the same polarity and the trait either + /// has no items or is annotated `#[marker]` and prevents item overrides. + pub fn impls_are_allowed_to_overlap( + self, + def_id1: DefId, + def_id2: DefId, + ) -> Option<ImplOverlapKind> { + // If either trait impl references an error, they're allowed to overlap, + // as one of them essentially doesn't exist. + if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error()) + || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error()) + { + return Some(ImplOverlapKind::Permitted { marker: false }); + } + + match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) { + (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => { + // `#[rustc_reservation_impl]` impls don't overlap with anything + debug!( + "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)", + def_id1, def_id2 + ); + return Some(ImplOverlapKind::Permitted { marker: false }); + } + (ImplPolarity::Positive, ImplPolarity::Negative) + | (ImplPolarity::Negative, ImplPolarity::Positive) => { + // `impl AutoTrait for Type` + `impl !AutoTrait for Type` + debug!( + "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)", + def_id1, def_id2 + ); + return None; + } + (ImplPolarity::Positive, ImplPolarity::Positive) + | (ImplPolarity::Negative, ImplPolarity::Negative) => {} + }; + + let is_marker_overlap = { + let is_marker_impl = |def_id: DefId| -> bool { + let trait_ref = self.impl_trait_ref(def_id); + trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker) + }; + is_marker_impl(def_id1) && is_marker_impl(def_id2) + }; + + if is_marker_overlap { + debug!( + "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)", + def_id1, def_id2 + ); + Some(ImplOverlapKind::Permitted { marker: true }) + } else { + if let Some(self_ty1) = self.issue33140_self_ty(def_id1) { + if let Some(self_ty2) = self.issue33140_self_ty(def_id2) { + if self_ty1 == self_ty2 { + debug!( + "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK", + def_id1, def_id2 + ); + return Some(ImplOverlapKind::Issue33140); + } else { + debug!( + "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}", + def_id1, def_id2, self_ty1, self_ty2 + ); + } + } + } + + debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2); + None + } + } + + /// Returns `ty::VariantDef` if `res` refers to a struct, + /// or variant or their constructors, panics otherwise. + pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef { + match res { + Res::Def(DefKind::Variant, did) => { + let enum_did = self.parent(did).unwrap(); + self.adt_def(enum_did).variant_with_id(did) + } + Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(), + Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => { + let variant_did = self.parent(variant_ctor_did).unwrap(); + let enum_did = self.parent(variant_did).unwrap(); + self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did) + } + Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => { + let struct_did = self.parent(ctor_did).expect("struct ctor has no parent"); + self.adt_def(struct_did).non_enum_variant() + } + _ => bug!("expect_variant_res used with unexpected res {:?}", res), + } + } + + pub fn item_name(self, id: DefId) -> Symbol { + if id.index == CRATE_DEF_INDEX { + self.original_crate_name(id.krate) + } else { + let def_key = self.def_key(id); + match def_key.disambiguated_data.data { + // The name of a constructor is that of its parent. + rustc_hir::definitions::DefPathData::Ctor => { + self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() }) + } + _ => def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| { + bug!("item_name: no name for {:?}", self.def_path(id)); + }), + } + } + } + + /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair. + pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> { + match instance { + ty::InstanceDef::Item(def) => { + if let Some((did, param_did)) = def.as_const_arg() { + self.optimized_mir_of_const_arg((did, param_did)) + } else { + self.optimized_mir(def.did) + } + } + ty::InstanceDef::VtableShim(..) + | ty::InstanceDef::ReifyShim(..) + | ty::InstanceDef::Intrinsic(..) + | ty::InstanceDef::FnPtrShim(..) + | ty::InstanceDef::Virtual(..) + | ty::InstanceDef::ClosureOnceShim { .. } + | ty::InstanceDef::DropGlue(..) + | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance), + } + } + + /// Gets the attributes of a definition. + pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> { + if let Some(did) = did.as_local() { + self.hir().attrs(self.hir().local_def_id_to_hir_id(did)) + } else { + self.item_attrs(did) + } + } + + /// Determines whether an item is annotated with an attribute. + pub fn has_attr(self, did: DefId, attr: Symbol) -> bool { + self.sess.contains_name(&self.get_attrs(did), attr) + } + + /// Returns `true` if this is an `auto trait`. + pub fn trait_is_auto(self, trait_def_id: DefId) -> bool { + self.trait_def(trait_def_id).has_auto_impl + } + + pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> { + self.optimized_mir(def_id).generator_layout.as_ref().unwrap() + } + + /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements. + /// If it implements no trait, returns `None`. + pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> { + self.impl_trait_ref(def_id).map(|tr| tr.def_id) + } + + /// If the given defid describes a method belonging to an impl, returns the + /// `DefId` of the impl that the method belongs to; otherwise, returns `None`. + pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> { + self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container { + TraitContainer(_) => None, + ImplContainer(def_id) => Some(def_id), + }) + } + + /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err` + /// with the name of the crate containing the impl. + pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> { + if let Some(impl_did) = impl_did.as_local() { + let hir_id = self.hir().local_def_id_to_hir_id(impl_did); + Ok(self.hir().span(hir_id)) + } else { + Err(self.crate_name(impl_did.krate)) + } + } + + /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with + /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed + /// definition's parent/scope to perform comparison. + pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool { + // We could use `Ident::eq` here, but we deliberately don't. The name + // comparison fails frequently, and we want to avoid the expensive + // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible. + use_name.name == def_name.name + && use_name + .span + .ctxt() + .hygienic_eq(def_name.span.ctxt(), self.expansion_that_defined(def_parent_def_id)) + } + + fn expansion_that_defined(self, scope: DefId) -> ExpnId { + match scope.as_local() { + Some(scope) => self.hir().definitions().expansion_that_defined(scope), + None => ExpnId::root(), + } + } + + pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident { + ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope)); + ident + } + + pub fn adjust_ident_and_get_scope( + self, + mut ident: Ident, + scope: DefId, + block: hir::HirId, + ) -> (Ident, DefId) { + let scope = + match ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope)) + { + Some(actual_expansion) => { + self.hir().definitions().parent_module_of_macro_def(actual_expansion) + } + None => self.parent_module(block).to_def_id(), + }; + (ident, scope) + } + + pub fn is_object_safe(self, key: DefId) -> bool { + self.object_safety_violations(key).is_empty() + } +} + +#[derive(Clone, HashStable)] +pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]); + +/// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition. +pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> { + if let Some(def_id) = def_id.as_local() { + if let Node::Item(item) = tcx.hir().get(tcx.hir().local_def_id_to_hir_id(def_id)) { + if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind { + return opaque_ty.impl_trait_fn; + } + } + } + None +} + +pub fn provide(providers: &mut ty::query::Providers) { + context::provide(providers); + erase_regions::provide(providers); + layout::provide(providers); + util::provide(providers); + super::util::bug::provide(providers); + *providers = ty::query::Providers { + trait_impls_of: trait_def::trait_impls_of_provider, + all_local_trait_impls: trait_def::all_local_trait_impls, + ..*providers + }; +} + +/// A map for the local crate mapping each type to a vector of its +/// inherent impls. This is not meant to be used outside of coherence; +/// rather, you should request the vector for a specific type via +/// `tcx.inherent_impls(def_id)` so as to minimize your dependencies +/// (constructing this map requires touching the entire crate). +#[derive(Clone, Debug, Default, HashStable)] +pub struct CrateInherentImpls { + pub inherent_impls: DefIdMap<Vec<DefId>>, +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)] +pub struct SymbolName<'tcx> { + /// `&str` gives a consistent ordering, which ensures reproducible builds. + pub name: &'tcx str, +} + +impl<'tcx> SymbolName<'tcx> { + pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> { + SymbolName { + name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) }, + } + } +} + +impl<'tcx> fmt::Display for SymbolName<'tcx> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(&self.name, fmt) + } +} + +impl<'tcx> fmt::Debug for SymbolName<'tcx> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(&self.name, fmt) + } +} diff --git a/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs b/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs new file mode 100644 index 00000000000..48a62b64604 --- /dev/null +++ b/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs @@ -0,0 +1,104 @@ +//! Methods for normalizing when you don't care about regions (and +//! aren't doing type inference). If either of those things don't +//! apply to you, use `infcx.normalize(...)`. +//! +//! The methods in this file use a `TypeFolder` to recursively process +//! contents, invoking the underlying +//! `normalize_generic_arg_after_erasing_regions` query for each type +//! or constant found within. (This underlying query is what is cached.) + +use crate::ty::fold::{TypeFoldable, TypeFolder}; +use crate::ty::subst::{Subst, SubstsRef}; +use crate::ty::{self, Ty, TyCtxt}; + +impl<'tcx> TyCtxt<'tcx> { + /// Erase the regions in `value` and then fully normalize all the + /// types found within. The result will also have regions erased. + /// + /// This is appropriate to use only after type-check: it assumes + /// that normalization will succeed, for example. + pub fn normalize_erasing_regions<T>(self, param_env: ty::ParamEnv<'tcx>, value: T) -> T + where + T: TypeFoldable<'tcx>, + { + debug!( + "normalize_erasing_regions::<{}>(value={:?}, param_env={:?})", + ::std::any::type_name::<T>(), + value, + param_env, + ); + + // Erase first before we do the real query -- this keeps the + // cache from being too polluted. + let value = self.erase_regions(&value); + if !value.has_projections() { + value + } else { + value.fold_with(&mut NormalizeAfterErasingRegionsFolder { tcx: self, param_env }) + } + } + + /// If you have a `Binder<T>`, you can do this to strip out the + /// late-bound regions and then normalize the result, yielding up + /// a `T` (with regions erased). This is appropriate when the + /// binder is being instantiated at the call site. + /// + /// N.B., currently, higher-ranked type bounds inhibit + /// normalization. Therefore, each time we erase them in + /// codegen, we need to normalize the contents. + pub fn normalize_erasing_late_bound_regions<T>( + self, + param_env: ty::ParamEnv<'tcx>, + value: &ty::Binder<T>, + ) -> T + where + T: TypeFoldable<'tcx>, + { + let value = self.erase_late_bound_regions(value); + self.normalize_erasing_regions(param_env, value) + } + + /// Monomorphizes a type from the AST by first applying the + /// in-scope substitutions and then normalizing any associated + /// types. + pub fn subst_and_normalize_erasing_regions<T>( + self, + param_substs: SubstsRef<'tcx>, + param_env: ty::ParamEnv<'tcx>, + value: &T, + ) -> T + where + T: TypeFoldable<'tcx>, + { + debug!( + "subst_and_normalize_erasing_regions(\ + param_substs={:?}, \ + value={:?}, \ + param_env={:?})", + param_substs, value, param_env, + ); + let substituted = value.subst(self, param_substs); + self.normalize_erasing_regions(param_env, substituted) + } +} + +struct NormalizeAfterErasingRegionsFolder<'tcx> { + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, +} + +impl TypeFolder<'tcx> for NormalizeAfterErasingRegionsFolder<'tcx> { + fn tcx(&self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { + let arg = self.param_env.and(ty.into()); + self.tcx.normalize_generic_arg_after_erasing_regions(arg).expect_ty() + } + + fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { + let arg = self.param_env.and(c.into()); + self.tcx.normalize_generic_arg_after_erasing_regions(arg).expect_const() + } +} diff --git a/compiler/rustc_middle/src/ty/outlives.rs b/compiler/rustc_middle/src/ty/outlives.rs new file mode 100644 index 00000000000..1a8693b8df7 --- /dev/null +++ b/compiler/rustc_middle/src/ty/outlives.rs @@ -0,0 +1,206 @@ +// The outlines relation `T: 'a` or `'a: 'b`. This code frequently +// refers to rules defined in RFC 1214 (`OutlivesFooBar`), so see that +// RFC for reference. + +use crate::ty::subst::{GenericArg, GenericArgKind}; +use crate::ty::{self, Ty, TyCtxt, TypeFoldable}; +use smallvec::SmallVec; + +#[derive(Debug)] +pub enum Component<'tcx> { + Region(ty::Region<'tcx>), + Param(ty::ParamTy), + UnresolvedInferenceVariable(ty::InferTy), + + // Projections like `T::Foo` are tricky because a constraint like + // `T::Foo: 'a` can be satisfied in so many ways. There may be a + // where-clause that says `T::Foo: 'a`, or the defining trait may + // include a bound like `type Foo: 'static`, or -- in the most + // conservative way -- we can prove that `T: 'a` (more generally, + // that all components in the projection outlive `'a`). This code + // is not in a position to judge which is the best technique, so + // we just product the projection as a component and leave it to + // the consumer to decide (but see `EscapingProjection` below). + Projection(ty::ProjectionTy<'tcx>), + + // In the case where a projection has escaping regions -- meaning + // regions bound within the type itself -- we always use + // the most conservative rule, which requires that all components + // outlive the bound. So for example if we had a type like this: + // + // for<'a> Trait1< <T as Trait2<'a,'b>>::Foo > + // ~~~~~~~~~~~~~~~~~~~~~~~~~ + // + // then the inner projection (underlined) has an escaping region + // `'a`. We consider that outer trait `'c` to meet a bound if `'b` + // outlives `'b: 'c`, and we don't consider whether the trait + // declares that `Foo: 'static` etc. Therefore, we just return the + // free components of such a projection (in this case, `'b`). + // + // However, in the future, we may want to get smarter, and + // actually return a "higher-ranked projection" here. Therefore, + // we mark that these components are part of an escaping + // projection, so that implied bounds code can avoid relying on + // them. This gives us room to improve the regionck reasoning in + // the future without breaking backwards compat. + EscapingProjection(Vec<Component<'tcx>>), +} + +impl<'tcx> TyCtxt<'tcx> { + /// Push onto `out` all the things that must outlive `'a` for the condition + /// `ty0: 'a` to hold. Note that `ty0` must be a **fully resolved type**. + pub fn push_outlives_components(self, ty0: Ty<'tcx>, out: &mut SmallVec<[Component<'tcx>; 4]>) { + compute_components(self, ty0, out); + debug!("components({:?}) = {:?}", ty0, out); + } +} + +fn compute_components(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, out: &mut SmallVec<[Component<'tcx>; 4]>) { + // Descend through the types, looking for the various "base" + // components and collecting them into `out`. This is not written + // with `collect()` because of the need to sometimes skip subtrees + // in the `subtys` iterator (e.g., when encountering a + // projection). + match ty.kind { + ty::FnDef(_, substs) => { + // HACK(eddyb) ignore lifetimes found shallowly in `substs`. + // This is inconsistent with `ty::Adt` (including all substs) + // and with `ty::Closure` (ignoring all substs other than + // upvars, of which a `ty::FnDef` doesn't have any), but + // consistent with previous (accidental) behavior. + // See https://github.com/rust-lang/rust/issues/70917 + // for further background and discussion. + for child in substs { + match child.unpack() { + GenericArgKind::Type(ty) => { + compute_components(tcx, ty, out); + } + GenericArgKind::Lifetime(_) => {} + GenericArgKind::Const(_) => { + compute_components_recursive(tcx, child, out); + } + } + } + } + + ty::Array(element, _) => { + // Don't look into the len const as it doesn't affect regions + compute_components(tcx, element, out); + } + + ty::Closure(_, ref substs) => { + for upvar_ty in substs.as_closure().upvar_tys() { + compute_components(tcx, upvar_ty, out); + } + } + + ty::Generator(_, ref substs, _) => { + // Same as the closure case + for upvar_ty in substs.as_generator().upvar_tys() { + compute_components(tcx, upvar_ty, out); + } + + // We ignore regions in the generator interior as we don't + // want these to affect region inference + } + + // All regions are bound inside a witness + ty::GeneratorWitness(..) => (), + + // OutlivesTypeParameterEnv -- the actual checking that `X:'a` + // is implied by the environment is done in regionck. + ty::Param(p) => { + out.push(Component::Param(p)); + } + + // For projections, we prefer to generate an obligation like + // `<P0 as Trait<P1...Pn>>::Foo: 'a`, because this gives the + // regionck more ways to prove that it holds. However, + // regionck is not (at least currently) prepared to deal with + // higher-ranked regions that may appear in the + // trait-ref. Therefore, if we see any higher-ranke regions, + // we simply fallback to the most restrictive rule, which + // requires that `Pi: 'a` for all `i`. + ty::Projection(ref data) => { + if !data.has_escaping_bound_vars() { + // best case: no escaping regions, so push the + // projection and skip the subtree (thus generating no + // constraints for Pi). This defers the choice between + // the rules OutlivesProjectionEnv, + // OutlivesProjectionTraitDef, and + // OutlivesProjectionComponents to regionck. + out.push(Component::Projection(*data)); + } else { + // fallback case: hard code + // OutlivesProjectionComponents. Continue walking + // through and constrain Pi. + let mut subcomponents = smallvec![]; + compute_components_recursive(tcx, ty.into(), &mut subcomponents); + out.push(Component::EscapingProjection(subcomponents.into_iter().collect())); + } + } + + // We assume that inference variables are fully resolved. + // So, if we encounter an inference variable, just record + // the unresolved variable as a component. + ty::Infer(infer_ty) => { + out.push(Component::UnresolvedInferenceVariable(infer_ty)); + } + + // Most types do not introduce any region binders, nor + // involve any other subtle cases, and so the WF relation + // simply constraints any regions referenced directly by + // the type and then visits the types that are lexically + // contained within. (The comments refer to relevant rules + // from RFC1214.) + ty::Bool | // OutlivesScalar + ty::Char | // OutlivesScalar + ty::Int(..) | // OutlivesScalar + ty::Uint(..) | // OutlivesScalar + ty::Float(..) | // OutlivesScalar + ty::Never | // ... + ty::Adt(..) | // OutlivesNominalType + ty::Opaque(..) | // OutlivesNominalType (ish) + ty::Foreign(..) | // OutlivesNominalType + ty::Str | // OutlivesScalar (ish) + ty::Slice(..) | // ... + ty::RawPtr(..) | // ... + ty::Ref(..) | // OutlivesReference + ty::Tuple(..) | // ... + ty::FnPtr(_) | // OutlivesFunction (*) + ty::Dynamic(..) | // OutlivesObject, OutlivesFragment (*) + ty::Placeholder(..) | + ty::Bound(..) | + ty::Error(_) => { + // (*) Function pointers and trait objects are both binders. + // In the RFC, this means we would add the bound regions to + // the "bound regions list". In our representation, no such + // list is maintained explicitly, because bound regions + // themselves can be readily identified. + compute_components_recursive(tcx, ty.into(), out); + } + } +} + +fn compute_components_recursive( + tcx: TyCtxt<'tcx>, + parent: GenericArg<'tcx>, + out: &mut SmallVec<[Component<'tcx>; 4]>, +) { + for child in parent.walk_shallow() { + match child.unpack() { + GenericArgKind::Type(ty) => { + compute_components(tcx, ty, out); + } + GenericArgKind::Lifetime(lt) => { + // Ignore late-bound regions. + if !lt.is_late_bound() { + out.push(Component::Region(lt)); + } + } + GenericArgKind::Const(_) => { + compute_components_recursive(tcx, child, out); + } + } + } +} diff --git a/compiler/rustc_middle/src/ty/print/mod.rs b/compiler/rustc_middle/src/ty/print/mod.rs new file mode 100644 index 00000000000..6c8f23c139f --- /dev/null +++ b/compiler/rustc_middle/src/ty/print/mod.rs @@ -0,0 +1,346 @@ +use crate::ty::subst::{GenericArg, Subst}; +use crate::ty::{self, DefIdTree, Ty, TyCtxt}; + +use rustc_data_structures::fx::FxHashSet; +use rustc_hir::def_id::{CrateNum, DefId}; +use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData}; + +// `pretty` is a separate module only for organization. +mod pretty; +pub use self::pretty::*; + +pub mod obsolete; + +// FIXME(eddyb) false positive, the lifetime parameters are used with `P: Printer<...>`. +#[allow(unused_lifetimes)] +pub trait Print<'tcx, P> { + type Output; + type Error; + + fn print(&self, cx: P) -> Result<Self::Output, Self::Error>; +} + +/// Interface for outputting user-facing "type-system entities" +/// (paths, types, lifetimes, constants, etc.) as a side-effect +/// (e.g. formatting, like `PrettyPrinter` implementors do) or by +/// constructing some alternative representation (e.g. an AST), +/// which the associated types allow passing through the methods. +/// +/// For pretty-printing/formatting in particular, see `PrettyPrinter`. +// +// FIXME(eddyb) find a better name; this is more general than "printing". +pub trait Printer<'tcx>: Sized { + type Error; + + type Path; + type Region; + type Type; + type DynExistential; + type Const; + + fn tcx(&'a self) -> TyCtxt<'tcx>; + + fn print_def_path( + self, + def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error> { + self.default_print_def_path(def_id, substs) + } + + fn print_impl_path( + self, + impl_def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error> { + self.default_print_impl_path(impl_def_id, substs, self_ty, trait_ref) + } + + fn print_region(self, region: ty::Region<'_>) -> Result<Self::Region, Self::Error>; + + fn print_type(self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error>; + + fn print_dyn_existential( + self, + predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>, + ) -> Result<Self::DynExistential, Self::Error>; + + fn print_const(self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error>; + + fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error>; + + fn path_qualified( + self, + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error>; + + fn path_append_impl( + self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + disambiguated_data: &DisambiguatedDefPathData, + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error>; + + fn path_append( + self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + disambiguated_data: &DisambiguatedDefPathData, + ) -> Result<Self::Path, Self::Error>; + + fn path_generic_args( + self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + args: &[GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error>; + + // Defaults (should not be overridden): + + fn default_print_def_path( + self, + def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error> { + debug!("default_print_def_path: def_id={:?}, substs={:?}", def_id, substs); + let key = self.tcx().def_key(def_id); + debug!("default_print_def_path: key={:?}", key); + + match key.disambiguated_data.data { + DefPathData::CrateRoot => { + assert!(key.parent.is_none()); + self.path_crate(def_id.krate) + } + + DefPathData::Impl => { + let generics = self.tcx().generics_of(def_id); + let mut self_ty = self.tcx().type_of(def_id); + let mut impl_trait_ref = self.tcx().impl_trait_ref(def_id); + if substs.len() >= generics.count() { + self_ty = self_ty.subst(self.tcx(), substs); + impl_trait_ref = impl_trait_ref.subst(self.tcx(), substs); + } + self.print_impl_path(def_id, substs, self_ty, impl_trait_ref) + } + + _ => { + let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id }; + + let mut parent_substs = substs; + let mut trait_qualify_parent = false; + if !substs.is_empty() { + let generics = self.tcx().generics_of(def_id); + parent_substs = &substs[..generics.parent_count.min(substs.len())]; + + match key.disambiguated_data.data { + // Closures' own generics are only captures, don't print them. + DefPathData::ClosureExpr => {} + + // If we have any generic arguments to print, we do that + // on top of the same path, but without its own generics. + _ => { + if !generics.params.is_empty() && substs.len() >= generics.count() { + let args = self.generic_args_to_print(generics, substs); + return self.path_generic_args( + |cx| cx.print_def_path(def_id, parent_substs), + args, + ); + } + } + } + + // FIXME(eddyb) try to move this into the parent's printing + // logic, instead of doing it when printing the child. + trait_qualify_parent = generics.has_self + && generics.parent == Some(parent_def_id) + && parent_substs.len() == generics.parent_count + && self.tcx().generics_of(parent_def_id).parent_count == 0; + } + + self.path_append( + |cx: Self| { + if trait_qualify_parent { + let trait_ref = ty::TraitRef::new( + parent_def_id, + cx.tcx().intern_substs(parent_substs), + ); + cx.path_qualified(trait_ref.self_ty(), Some(trait_ref)) + } else { + cx.print_def_path(parent_def_id, parent_substs) + } + }, + &key.disambiguated_data, + ) + } + } + } + + fn generic_args_to_print( + &self, + generics: &'tcx ty::Generics, + substs: &'tcx [GenericArg<'tcx>], + ) -> &'tcx [GenericArg<'tcx>] { + let mut own_params = generics.parent_count..generics.count(); + + // Don't print args for `Self` parameters (of traits). + if generics.has_self && own_params.start == 0 { + own_params.start = 1; + } + + // Don't print args that are the defaults of their respective parameters. + own_params.end -= generics + .params + .iter() + .rev() + .take_while(|param| { + match param.kind { + ty::GenericParamDefKind::Lifetime => false, + ty::GenericParamDefKind::Type { has_default, .. } => { + has_default + && substs[param.index as usize] + == GenericArg::from( + self.tcx().type_of(param.def_id).subst(self.tcx(), substs), + ) + } + ty::GenericParamDefKind::Const => false, // FIXME(const_generics:defaults) + } + }) + .count(); + + &substs[own_params] + } + + fn default_print_impl_path( + self, + impl_def_id: DefId, + _substs: &'tcx [GenericArg<'tcx>], + self_ty: Ty<'tcx>, + impl_trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error> { + debug!( + "default_print_impl_path: impl_def_id={:?}, self_ty={}, impl_trait_ref={:?}", + impl_def_id, self_ty, impl_trait_ref + ); + + let key = self.tcx().def_key(impl_def_id); + let parent_def_id = DefId { index: key.parent.unwrap(), ..impl_def_id }; + + // Decide whether to print the parent path for the impl. + // Logically, since impls are global, it's never needed, but + // users may find it useful. Currently, we omit the parent if + // the impl is either in the same module as the self-type or + // as the trait. + let in_self_mod = match characteristic_def_id_of_type(self_ty) { + None => false, + Some(ty_def_id) => self.tcx().parent(ty_def_id) == Some(parent_def_id), + }; + let in_trait_mod = match impl_trait_ref { + None => false, + Some(trait_ref) => self.tcx().parent(trait_ref.def_id) == Some(parent_def_id), + }; + + if !in_self_mod && !in_trait_mod { + // If the impl is not co-located with either self-type or + // trait-type, then fallback to a format that identifies + // the module more clearly. + self.path_append_impl( + |cx| cx.print_def_path(parent_def_id, &[]), + &key.disambiguated_data, + self_ty, + impl_trait_ref, + ) + } else { + // Otherwise, try to give a good form that would be valid language + // syntax. Preferably using associated item notation. + self.path_qualified(self_ty, impl_trait_ref) + } + } +} + +/// As a heuristic, when we see an impl, if we see that the +/// 'self type' is a type defined in the same module as the impl, +/// we can omit including the path to the impl itself. This +/// function tries to find a "characteristic `DefId`" for a +/// type. It's just a heuristic so it makes some questionable +/// decisions and we may want to adjust it later. +pub fn characteristic_def_id_of_type(ty: Ty<'_>) -> Option<DefId> { + match ty.kind { + ty::Adt(adt_def, _) => Some(adt_def.did), + + ty::Dynamic(data, ..) => data.principal_def_id(), + + ty::Array(subty, _) | ty::Slice(subty) => characteristic_def_id_of_type(subty), + + ty::RawPtr(mt) => characteristic_def_id_of_type(mt.ty), + + ty::Ref(_, ty, _) => characteristic_def_id_of_type(ty), + + ty::Tuple(ref tys) => { + tys.iter().find_map(|ty| characteristic_def_id_of_type(ty.expect_ty())) + } + + ty::FnDef(def_id, _) + | ty::Closure(def_id, _) + | ty::Generator(def_id, _, _) + | ty::Foreign(def_id) => Some(def_id), + + ty::Bool + | ty::Char + | ty::Int(_) + | ty::Uint(_) + | ty::Str + | ty::FnPtr(_) + | ty::Projection(_) + | ty::Placeholder(..) + | ty::Param(_) + | ty::Opaque(..) + | ty::Infer(_) + | ty::Bound(..) + | ty::Error(_) + | ty::GeneratorWitness(..) + | ty::Never + | ty::Float(_) => None, + } +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for ty::RegionKind { + type Output = P::Region; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_region(self) + } +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for ty::Region<'_> { + type Output = P::Region; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_region(self) + } +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for Ty<'tcx> { + type Output = P::Type; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_type(self) + } +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for &'tcx ty::List<ty::ExistentialPredicate<'tcx>> { + type Output = P::DynExistential; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_dyn_existential(self) + } +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for &'tcx ty::Const<'tcx> { + type Output = P::Const; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_const(self) + } +} diff --git a/compiler/rustc_middle/src/ty/print/obsolete.rs b/compiler/rustc_middle/src/ty/print/obsolete.rs new file mode 100644 index 00000000000..2ea7cd2a6dc --- /dev/null +++ b/compiler/rustc_middle/src/ty/print/obsolete.rs @@ -0,0 +1,251 @@ +//! Allows for producing a unique string key for a mono item. +//! These keys are used by the handwritten auto-tests, so they need to be +//! predictable and human-readable. +//! +//! Note: A lot of this could looks very similar to what's already in `ty::print`. +//! FIXME(eddyb) implement a custom `PrettyPrinter` for this. + +use crate::bug; +use crate::ty::subst::SubstsRef; +use crate::ty::{self, Const, Instance, Ty, TyCtxt}; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use std::fmt::Write; +use std::iter; + +/// Same as `unique_type_name()` but with the result pushed onto the given +/// `output` parameter. +pub struct DefPathBasedNames<'tcx> { + tcx: TyCtxt<'tcx>, + omit_disambiguators: bool, + omit_local_crate_name: bool, +} + +impl DefPathBasedNames<'tcx> { + pub fn new(tcx: TyCtxt<'tcx>, omit_disambiguators: bool, omit_local_crate_name: bool) -> Self { + DefPathBasedNames { tcx, omit_disambiguators, omit_local_crate_name } + } + + // Pushes the type name of the specified type to the provided string. + // If `debug` is true, printing normally unprintable types is allowed + // (e.g. `ty::GeneratorWitness`). This parameter should only be set when + // this method is being used for logging purposes (e.g. with `debug!` or `info!`) + // When being used for codegen purposes, `debug` should be set to `false` + // in order to catch unexpected types that should never end up in a type name. + pub fn push_type_name(&self, t: Ty<'tcx>, output: &mut String, debug: bool) { + match t.kind { + ty::Bool => output.push_str("bool"), + ty::Char => output.push_str("char"), + ty::Str => output.push_str("str"), + ty::Never => output.push_str("!"), + ty::Int(ty) => output.push_str(ty.name_str()), + ty::Uint(ty) => output.push_str(ty.name_str()), + ty::Float(ty) => output.push_str(ty.name_str()), + ty::Adt(adt_def, substs) => { + self.push_def_path(adt_def.did, output); + self.push_generic_params(substs, iter::empty(), output, debug); + } + ty::Tuple(component_types) => { + output.push('('); + for component_type in component_types { + self.push_type_name(component_type.expect_ty(), output, debug); + output.push_str(", "); + } + if !component_types.is_empty() { + output.pop(); + output.pop(); + } + output.push(')'); + } + ty::RawPtr(ty::TypeAndMut { ty: inner_type, mutbl }) => { + output.push('*'); + match mutbl { + hir::Mutability::Not => output.push_str("const "), + hir::Mutability::Mut => output.push_str("mut "), + } + + self.push_type_name(inner_type, output, debug); + } + ty::Ref(_, inner_type, mutbl) => { + output.push('&'); + output.push_str(mutbl.prefix_str()); + + self.push_type_name(inner_type, output, debug); + } + ty::Array(inner_type, len) => { + output.push('['); + self.push_type_name(inner_type, output, debug); + let len = len.eval_usize(self.tcx, ty::ParamEnv::reveal_all()); + write!(output, "; {}", len).unwrap(); + output.push(']'); + } + ty::Slice(inner_type) => { + output.push('['); + self.push_type_name(inner_type, output, debug); + output.push(']'); + } + ty::Dynamic(ref trait_data, ..) => { + if let Some(principal) = trait_data.principal() { + self.push_def_path(principal.def_id(), output); + self.push_generic_params( + principal.skip_binder().substs, + trait_data.projection_bounds(), + output, + debug, + ); + } else { + output.push_str("dyn '_"); + } + } + ty::Foreign(did) => self.push_def_path(did, output), + ty::FnDef(..) | ty::FnPtr(_) => { + let sig = t.fn_sig(self.tcx); + output.push_str(sig.unsafety().prefix_str()); + + let abi = sig.abi(); + if abi != ::rustc_target::spec::abi::Abi::Rust { + output.push_str("extern \""); + output.push_str(abi.name()); + output.push_str("\" "); + } + + output.push_str("fn("); + + let sig = + self.tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), &sig); + + if !sig.inputs().is_empty() { + for ¶meter_type in sig.inputs() { + self.push_type_name(parameter_type, output, debug); + output.push_str(", "); + } + output.pop(); + output.pop(); + } + + if sig.c_variadic { + if !sig.inputs().is_empty() { + output.push_str(", ..."); + } else { + output.push_str("..."); + } + } + + output.push(')'); + + if !sig.output().is_unit() { + output.push_str(" -> "); + self.push_type_name(sig.output(), output, debug); + } + } + ty::Generator(def_id, substs, _) | ty::Closure(def_id, substs) => { + self.push_def_path(def_id, output); + let generics = self.tcx.generics_of(self.tcx.closure_base_def_id(def_id)); + let substs = substs.truncate_to(self.tcx, generics); + self.push_generic_params(substs, iter::empty(), output, debug); + } + ty::Param(_) => { + output.push_str(&t.to_string()); + } + ty::Error(_) + | ty::Bound(..) + | ty::Infer(_) + | ty::Placeholder(..) + | ty::Projection(..) + | ty::GeneratorWitness(_) + | ty::Opaque(..) => { + if debug { + output.push_str(&format!("`{:?}`", t)); + } else { + bug!( + "DefPathBasedNames: trying to create type name for unexpected type: {:?}", + t, + ); + } + } + } + } + + // Pushes the the name of the specified const to the provided string. + // If `debug` is true, the unprintable types of constants will be printed with `fmt::Debug` + // (see `push_type_name` for more details). + pub fn push_const_name(&self, ct: &Const<'tcx>, output: &mut String, debug: bool) { + write!(output, "{}", ct).unwrap(); + output.push_str(": "); + self.push_type_name(ct.ty, output, debug); + } + + pub fn push_def_path(&self, def_id: DefId, output: &mut String) { + let def_path = self.tcx.def_path(def_id); + + // some_crate:: + if !(self.omit_local_crate_name && def_id.is_local()) { + output.push_str(&self.tcx.crate_name(def_path.krate).as_str()); + output.push_str("::"); + } + + // foo::bar::ItemName:: + for part in self.tcx.def_path(def_id).data { + if self.omit_disambiguators { + write!(output, "{}::", part.data.as_symbol()).unwrap(); + } else { + write!(output, "{}[{}]::", part.data.as_symbol(), part.disambiguator).unwrap(); + } + } + + // remove final "::" + output.pop(); + output.pop(); + } + + fn push_generic_params<I>( + &self, + substs: SubstsRef<'tcx>, + projections: I, + output: &mut String, + debug: bool, + ) where + I: Iterator<Item = ty::PolyExistentialProjection<'tcx>>, + { + let mut projections = projections.peekable(); + if substs.non_erasable_generics().next().is_none() && projections.peek().is_none() { + return; + } + + output.push('<'); + + for type_parameter in substs.types() { + self.push_type_name(type_parameter, output, debug); + output.push_str(", "); + } + + for projection in projections { + let projection = projection.skip_binder(); + let name = &self.tcx.associated_item(projection.item_def_id).ident.as_str(); + output.push_str(name); + output.push_str("="); + self.push_type_name(projection.ty, output, debug); + output.push_str(", "); + } + + for const_parameter in substs.consts() { + self.push_const_name(const_parameter, output, debug); + output.push_str(", "); + } + + output.pop(); + output.pop(); + + output.push('>'); + } + + pub fn push_instance_as_string( + &self, + instance: Instance<'tcx>, + output: &mut String, + debug: bool, + ) { + self.push_def_path(instance.def_id(), output); + self.push_generic_params(instance.substs, iter::empty(), output, debug); + } +} diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs new file mode 100644 index 00000000000..999a1d52a26 --- /dev/null +++ b/compiler/rustc_middle/src/ty/print/pretty.rs @@ -0,0 +1,2066 @@ +use crate::middle::cstore::{ExternCrate, ExternCrateSource}; +use crate::mir::interpret::{AllocId, ConstValue, GlobalAlloc, Pointer, Scalar}; +use crate::ty::layout::IntegerExt; +use crate::ty::subst::{GenericArg, GenericArgKind, Subst}; +use crate::ty::{self, ConstInt, DefIdTree, ParamConst, Ty, TyCtxt, TypeFoldable}; +use rustc_apfloat::ieee::{Double, Single}; +use rustc_apfloat::Float; +use rustc_ast as ast; +use rustc_attr::{SignedInt, UnsignedInt}; +use rustc_hir as hir; +use rustc_hir::def::{CtorKind, DefKind, Namespace}; +use rustc_hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE}; +use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData}; +use rustc_span::symbol::{kw, Ident, Symbol}; +use rustc_target::abi::{Integer, Size}; +use rustc_target::spec::abi::Abi; + +use std::cell::Cell; +use std::char; +use std::collections::BTreeMap; +use std::fmt::{self, Write as _}; +use std::ops::{Deref, DerefMut}; + +// `pretty` is a separate module only for organization. +use super::*; + +macro_rules! p { + (@write($($data:expr),+)) => { + write!(scoped_cx!(), $($data),+)? + }; + (@print($x:expr)) => { + scoped_cx!() = $x.print(scoped_cx!())? + }; + (@$method:ident($($arg:expr),*)) => { + scoped_cx!() = scoped_cx!().$method($($arg),*)? + }; + ($($kind:ident $data:tt),+) => {{ + $(p!(@$kind $data);)+ + }}; +} +macro_rules! define_scoped_cx { + ($cx:ident) => { + #[allow(unused_macros)] + macro_rules! scoped_cx { + () => { + $cx + }; + } + }; +} + +thread_local! { + static FORCE_IMPL_FILENAME_LINE: Cell<bool> = Cell::new(false); + static SHOULD_PREFIX_WITH_CRATE: Cell<bool> = Cell::new(false); + static NO_QUERIES: Cell<bool> = Cell::new(false); +} + +/// Avoids running any queries during any prints that occur +/// during the closure. This may alter the appearance of some +/// types (e.g. forcing verbose printing for opaque types). +/// This method is used during some queries (e.g. `predicates_of` +/// for opaque types), to ensure that any debug printing that +/// occurs during the query computation does not end up recursively +/// calling the same query. +pub fn with_no_queries<F: FnOnce() -> R, R>(f: F) -> R { + NO_QUERIES.with(|no_queries| { + let old = no_queries.replace(true); + let result = f(); + no_queries.set(old); + result + }) +} + +/// Force us to name impls with just the filename/line number. We +/// normally try to use types. But at some points, notably while printing +/// cycle errors, this can result in extra or suboptimal error output, +/// so this variable disables that check. +pub fn with_forced_impl_filename_line<F: FnOnce() -> R, R>(f: F) -> R { + FORCE_IMPL_FILENAME_LINE.with(|force| { + let old = force.replace(true); + let result = f(); + force.set(old); + result + }) +} + +/// Adds the `crate::` prefix to paths where appropriate. +pub fn with_crate_prefix<F: FnOnce() -> R, R>(f: F) -> R { + SHOULD_PREFIX_WITH_CRATE.with(|flag| { + let old = flag.replace(true); + let result = f(); + flag.set(old); + result + }) +} + +/// The "region highlights" are used to control region printing during +/// specific error messages. When a "region highlight" is enabled, it +/// gives an alternate way to print specific regions. For now, we +/// always print those regions using a number, so something like "`'0`". +/// +/// Regions not selected by the region highlight mode are presently +/// unaffected. +#[derive(Copy, Clone, Default)] +pub struct RegionHighlightMode { + /// If enabled, when we see the selected region, use "`'N`" + /// instead of the ordinary behavior. + highlight_regions: [Option<(ty::RegionKind, usize)>; 3], + + /// If enabled, when printing a "free region" that originated from + /// the given `ty::BoundRegion`, print it as "`'1`". Free regions that would ordinarily + /// have names print as normal. + /// + /// This is used when you have a signature like `fn foo(x: &u32, + /// y: &'a u32)` and we want to give a name to the region of the + /// reference `x`. + highlight_bound_region: Option<(ty::BoundRegion, usize)>, +} + +impl RegionHighlightMode { + /// If `region` and `number` are both `Some`, invokes + /// `highlighting_region`. + pub fn maybe_highlighting_region( + &mut self, + region: Option<ty::Region<'_>>, + number: Option<usize>, + ) { + if let Some(k) = region { + if let Some(n) = number { + self.highlighting_region(k, n); + } + } + } + + /// Highlights the region inference variable `vid` as `'N`. + pub fn highlighting_region(&mut self, region: ty::Region<'_>, number: usize) { + let num_slots = self.highlight_regions.len(); + let first_avail_slot = + self.highlight_regions.iter_mut().find(|s| s.is_none()).unwrap_or_else(|| { + bug!("can only highlight {} placeholders at a time", num_slots,) + }); + *first_avail_slot = Some((*region, number)); + } + + /// Convenience wrapper for `highlighting_region`. + pub fn highlighting_region_vid(&mut self, vid: ty::RegionVid, number: usize) { + self.highlighting_region(&ty::ReVar(vid), number) + } + + /// Returns `Some(n)` with the number to use for the given region, if any. + fn region_highlighted(&self, region: ty::Region<'_>) -> Option<usize> { + self.highlight_regions.iter().find_map(|h| match h { + Some((r, n)) if r == region => Some(*n), + _ => None, + }) + } + + /// Highlight the given bound region. + /// We can only highlight one bound region at a time. See + /// the field `highlight_bound_region` for more detailed notes. + pub fn highlighting_bound_region(&mut self, br: ty::BoundRegion, number: usize) { + assert!(self.highlight_bound_region.is_none()); + self.highlight_bound_region = Some((br, number)); + } +} + +/// Trait for printers that pretty-print using `fmt::Write` to the printer. +pub trait PrettyPrinter<'tcx>: + Printer< + 'tcx, + Error = fmt::Error, + Path = Self, + Region = Self, + Type = Self, + DynExistential = Self, + Const = Self, + > + fmt::Write +{ + /// Like `print_def_path` but for value paths. + fn print_value_path( + self, + def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error> { + self.print_def_path(def_id, substs) + } + + fn in_binder<T>(self, value: &ty::Binder<T>) -> Result<Self, Self::Error> + where + T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>, + { + value.as_ref().skip_binder().print(self) + } + + /// Prints comma-separated elements. + fn comma_sep<T>(mut self, mut elems: impl Iterator<Item = T>) -> Result<Self, Self::Error> + where + T: Print<'tcx, Self, Output = Self, Error = Self::Error>, + { + if let Some(first) = elems.next() { + self = first.print(self)?; + for elem in elems { + self.write_str(", ")?; + self = elem.print(self)?; + } + } + Ok(self) + } + + /// Prints `{f: t}` or `{f as t}` depending on the `cast` argument + fn typed_value( + mut self, + f: impl FnOnce(Self) -> Result<Self, Self::Error>, + t: impl FnOnce(Self) -> Result<Self, Self::Error>, + conversion: &str, + ) -> Result<Self::Const, Self::Error> { + self.write_str("{")?; + self = f(self)?; + self.write_str(conversion)?; + self = t(self)?; + self.write_str("}")?; + Ok(self) + } + + /// Prints `<...>` around what `f` prints. + fn generic_delimiters( + self, + f: impl FnOnce(Self) -> Result<Self, Self::Error>, + ) -> Result<Self, Self::Error>; + + /// Returns `true` if the region should be printed in + /// optional positions, e.g., `&'a T` or `dyn Tr + 'b`. + /// This is typically the case for all non-`'_` regions. + fn region_should_not_be_omitted(&self, region: ty::Region<'_>) -> bool; + + // Defaults (should not be overridden): + + /// If possible, this returns a global path resolving to `def_id` that is visible + /// from at least one local module, and returns `true`. If the crate defining `def_id` is + /// declared with an `extern crate`, the path is guaranteed to use the `extern crate`. + fn try_print_visible_def_path(self, def_id: DefId) -> Result<(Self, bool), Self::Error> { + let mut callers = Vec::new(); + self.try_print_visible_def_path_recur(def_id, &mut callers) + } + + /// Does the work of `try_print_visible_def_path`, building the + /// full definition path recursively before attempting to + /// post-process it into the valid and visible version that + /// accounts for re-exports. + /// + /// This method should only be called by itself or + /// `try_print_visible_def_path`. + /// + /// `callers` is a chain of visible_parent's leading to `def_id`, + /// to support cycle detection during recursion. + fn try_print_visible_def_path_recur( + mut self, + def_id: DefId, + callers: &mut Vec<DefId>, + ) -> Result<(Self, bool), Self::Error> { + define_scoped_cx!(self); + + debug!("try_print_visible_def_path: def_id={:?}", def_id); + + // If `def_id` is a direct or injected extern crate, return the + // path to the crate followed by the path to the item within the crate. + if def_id.index == CRATE_DEF_INDEX { + let cnum = def_id.krate; + + if cnum == LOCAL_CRATE { + return Ok((self.path_crate(cnum)?, true)); + } + + // In local mode, when we encounter a crate other than + // LOCAL_CRATE, execution proceeds in one of two ways: + // + // 1. For a direct dependency, where user added an + // `extern crate` manually, we put the `extern + // crate` as the parent. So you wind up with + // something relative to the current crate. + // 2. For an extern inferred from a path or an indirect crate, + // where there is no explicit `extern crate`, we just prepend + // the crate name. + match self.tcx().extern_crate(def_id) { + Some(&ExternCrate { src, dependency_of, span, .. }) => match (src, dependency_of) { + (ExternCrateSource::Extern(def_id), LOCAL_CRATE) => { + debug!("try_print_visible_def_path: def_id={:?}", def_id); + return Ok(( + if !span.is_dummy() { + self.print_def_path(def_id, &[])? + } else { + self.path_crate(cnum)? + }, + true, + )); + } + (ExternCrateSource::Path, LOCAL_CRATE) => { + debug!("try_print_visible_def_path: def_id={:?}", def_id); + return Ok((self.path_crate(cnum)?, true)); + } + _ => {} + }, + None => { + return Ok((self.path_crate(cnum)?, true)); + } + } + } + + if def_id.is_local() { + return Ok((self, false)); + } + + let visible_parent_map = self.tcx().visible_parent_map(LOCAL_CRATE); + + let mut cur_def_key = self.tcx().def_key(def_id); + debug!("try_print_visible_def_path: cur_def_key={:?}", cur_def_key); + + // For a constructor, we want the name of its parent rather than <unnamed>. + if let DefPathData::Ctor = cur_def_key.disambiguated_data.data { + let parent = DefId { + krate: def_id.krate, + index: cur_def_key + .parent + .expect("`DefPathData::Ctor` / `VariantData` missing a parent"), + }; + + cur_def_key = self.tcx().def_key(parent); + } + + let visible_parent = match visible_parent_map.get(&def_id).cloned() { + Some(parent) => parent, + None => return Ok((self, false)), + }; + if callers.contains(&visible_parent) { + return Ok((self, false)); + } + callers.push(visible_parent); + // HACK(eddyb) this bypasses `path_append`'s prefix printing to avoid + // knowing ahead of time whether the entire path will succeed or not. + // To support printers that do not implement `PrettyPrinter`, a `Vec` or + // linked list on the stack would need to be built, before any printing. + match self.try_print_visible_def_path_recur(visible_parent, callers)? { + (cx, false) => return Ok((cx, false)), + (cx, true) => self = cx, + } + callers.pop(); + let actual_parent = self.tcx().parent(def_id); + debug!( + "try_print_visible_def_path: visible_parent={:?} actual_parent={:?}", + visible_parent, actual_parent, + ); + + let mut data = cur_def_key.disambiguated_data.data; + debug!( + "try_print_visible_def_path: data={:?} visible_parent={:?} actual_parent={:?}", + data, visible_parent, actual_parent, + ); + + match data { + // In order to output a path that could actually be imported (valid and visible), + // we need to handle re-exports correctly. + // + // For example, take `std::os::unix::process::CommandExt`, this trait is actually + // defined at `std::sys::unix::ext::process::CommandExt` (at time of writing). + // + // `std::os::unix` rexports the contents of `std::sys::unix::ext`. `std::sys` is + // private so the "true" path to `CommandExt` isn't accessible. + // + // In this case, the `visible_parent_map` will look something like this: + // + // (child) -> (parent) + // `std::sys::unix::ext::process::CommandExt` -> `std::sys::unix::ext::process` + // `std::sys::unix::ext::process` -> `std::sys::unix::ext` + // `std::sys::unix::ext` -> `std::os` + // + // This is correct, as the visible parent of `std::sys::unix::ext` is in fact + // `std::os`. + // + // When printing the path to `CommandExt` and looking at the `cur_def_key` that + // corresponds to `std::sys::unix::ext`, we would normally print `ext` and then go + // to the parent - resulting in a mangled path like + // `std::os::ext::process::CommandExt`. + // + // Instead, we must detect that there was a re-export and instead print `unix` + // (which is the name `std::sys::unix::ext` was re-exported as in `std::os`). To + // do this, we compare the parent of `std::sys::unix::ext` (`std::sys::unix`) with + // the visible parent (`std::os`). If these do not match, then we iterate over + // the children of the visible parent (as was done when computing + // `visible_parent_map`), looking for the specific child we currently have and then + // have access to the re-exported name. + DefPathData::TypeNs(ref mut name) if Some(visible_parent) != actual_parent => { + let reexport = self + .tcx() + .item_children(visible_parent) + .iter() + .find(|child| child.res.opt_def_id() == Some(def_id)) + .map(|child| child.ident.name); + if let Some(reexport) = reexport { + *name = reexport; + } + } + // Re-exported `extern crate` (#43189). + DefPathData::CrateRoot => { + data = DefPathData::TypeNs(self.tcx().original_crate_name(def_id.krate)); + } + _ => {} + } + debug!("try_print_visible_def_path: data={:?}", data); + + Ok((self.path_append(Ok, &DisambiguatedDefPathData { data, disambiguator: 0 })?, true)) + } + + fn pretty_path_qualified( + self, + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error> { + if trait_ref.is_none() { + // Inherent impls. Try to print `Foo::bar` for an inherent + // impl on `Foo`, but fallback to `<Foo>::bar` if self-type is + // anything other than a simple path. + match self_ty.kind { + ty::Adt(..) + | ty::Foreign(_) + | ty::Bool + | ty::Char + | ty::Str + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) => { + return self_ty.print(self); + } + + _ => {} + } + } + + self.generic_delimiters(|mut cx| { + define_scoped_cx!(cx); + + p!(print(self_ty)); + if let Some(trait_ref) = trait_ref { + p!(write(" as "), print(trait_ref.print_only_trait_path())); + } + Ok(cx) + }) + } + + fn pretty_path_append_impl( + mut self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error> { + self = print_prefix(self)?; + + self.generic_delimiters(|mut cx| { + define_scoped_cx!(cx); + + p!(write("impl ")); + if let Some(trait_ref) = trait_ref { + p!(print(trait_ref.print_only_trait_path()), write(" for ")); + } + p!(print(self_ty)); + + Ok(cx) + }) + } + + fn pretty_print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> { + define_scoped_cx!(self); + + match ty.kind { + ty::Bool => p!(write("bool")), + ty::Char => p!(write("char")), + ty::Int(t) => p!(write("{}", t.name_str())), + ty::Uint(t) => p!(write("{}", t.name_str())), + ty::Float(t) => p!(write("{}", t.name_str())), + ty::RawPtr(ref tm) => { + p!(write( + "*{} ", + match tm.mutbl { + hir::Mutability::Mut => "mut", + hir::Mutability::Not => "const", + } + )); + p!(print(tm.ty)) + } + ty::Ref(r, ty, mutbl) => { + p!(write("&")); + if self.region_should_not_be_omitted(r) { + p!(print(r), write(" ")); + } + p!(print(ty::TypeAndMut { ty, mutbl })) + } + ty::Never => p!(write("!")), + ty::Tuple(ref tys) => { + p!(write("("), comma_sep(tys.iter())); + if tys.len() == 1 { + p!(write(",")); + } + p!(write(")")) + } + ty::FnDef(def_id, substs) => { + let sig = self.tcx().fn_sig(def_id).subst(self.tcx(), substs); + p!(print(sig), write(" {{"), print_value_path(def_id, substs), write("}}")); + } + ty::FnPtr(ref bare_fn) => p!(print(bare_fn)), + ty::Infer(infer_ty) => { + if let ty::TyVar(ty_vid) = infer_ty { + if let Some(name) = self.infer_ty_name(ty_vid) { + p!(write("{}", name)) + } else { + p!(write("{}", infer_ty)) + } + } else { + p!(write("{}", infer_ty)) + } + } + ty::Error(_) => p!(write("[type error]")), + ty::Param(ref param_ty) => p!(write("{}", param_ty)), + ty::Bound(debruijn, bound_ty) => match bound_ty.kind { + ty::BoundTyKind::Anon => self.pretty_print_bound_var(debruijn, bound_ty.var)?, + ty::BoundTyKind::Param(p) => p!(write("{}", p)), + }, + ty::Adt(def, substs) => { + p!(print_def_path(def.did, substs)); + } + ty::Dynamic(data, r) => { + let print_r = self.region_should_not_be_omitted(r); + if print_r { + p!(write("(")); + } + p!(write("dyn "), print(data)); + if print_r { + p!(write(" + "), print(r), write(")")); + } + } + ty::Foreign(def_id) => { + p!(print_def_path(def_id, &[])); + } + ty::Projection(ref data) => p!(print(data)), + ty::Placeholder(placeholder) => p!(write("Placeholder({:?})", placeholder)), + ty::Opaque(def_id, substs) => { + // FIXME(eddyb) print this with `print_def_path`. + // We use verbose printing in 'NO_QUERIES' mode, to + // avoid needing to call `predicates_of`. This should + // only affect certain debug messages (e.g. messages printed + // from `rustc_middle::ty` during the computation of `tcx.predicates_of`), + // and should have no effect on any compiler output. + if self.tcx().sess.verbose() || NO_QUERIES.with(|q| q.get()) { + p!(write("Opaque({:?}, {:?})", def_id, substs)); + return Ok(self); + } + + return Ok(with_no_queries(|| { + let def_key = self.tcx().def_key(def_id); + if let Some(name) = def_key.disambiguated_data.data.get_opt_name() { + p!(write("{}", name)); + // FIXME(eddyb) print this with `print_def_path`. + if !substs.is_empty() { + p!(write("::")); + p!(generic_delimiters(|cx| cx.comma_sep(substs.iter()))); + } + return Ok(self); + } + // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`, + // by looking up the projections associated with the def_id. + let bounds = self.tcx().predicates_of(def_id).instantiate(self.tcx(), substs); + + let mut first = true; + let mut is_sized = false; + p!(write("impl")); + for predicate in bounds.predicates { + // Note: We can't use `to_opt_poly_trait_ref` here as `predicate` + // may contain unbound variables. We therefore do this manually. + // + // FIXME(lcnr): Find out why exactly this is the case :) + if let ty::PredicateAtom::Trait(pred, _) = + predicate.bound_atom(self.tcx()).skip_binder() + { + let trait_ref = ty::Binder::bind(pred.trait_ref); + // Don't print +Sized, but rather +?Sized if absent. + if Some(trait_ref.def_id()) == self.tcx().lang_items().sized_trait() { + is_sized = true; + continue; + } + + p!( + write("{}", if first { " " } else { "+" }), + print(trait_ref.print_only_trait_path()) + ); + first = false; + } + } + if !is_sized { + p!(write("{}?Sized", if first { " " } else { "+" })); + } else if first { + p!(write(" Sized")); + } + Ok(self) + })?); + } + ty::Str => p!(write("str")), + ty::Generator(did, substs, movability) => { + match movability { + hir::Movability::Movable => p!(write("[generator")), + hir::Movability::Static => p!(write("[static generator")), + } + + // FIXME(eddyb) should use `def_span`. + if let Some(did) = did.as_local() { + let hir_id = self.tcx().hir().local_def_id_to_hir_id(did); + let span = self.tcx().hir().span(hir_id); + p!(write("@{}", self.tcx().sess.source_map().span_to_string(span))); + + if substs.as_generator().is_valid() { + let upvar_tys = substs.as_generator().upvar_tys(); + let mut sep = " "; + for (&var_id, upvar_ty) in self + .tcx() + .upvars_mentioned(did) + .as_ref() + .iter() + .flat_map(|v| v.keys()) + .zip(upvar_tys) + { + p!(write("{}{}:", sep, self.tcx().hir().name(var_id)), print(upvar_ty)); + sep = ", "; + } + } + } else { + p!(write("@{}", self.tcx().def_path_str(did))); + + if substs.as_generator().is_valid() { + let upvar_tys = substs.as_generator().upvar_tys(); + let mut sep = " "; + for (index, upvar_ty) in upvar_tys.enumerate() { + p!(write("{}{}:", sep, index), print(upvar_ty)); + sep = ", "; + } + } + } + + if substs.as_generator().is_valid() { + p!(write(" "), print(substs.as_generator().witness())); + } + + p!(write("]")) + } + ty::GeneratorWitness(types) => { + p!(in_binder(&types)); + } + ty::Closure(did, substs) => { + p!(write("[closure")); + + // FIXME(eddyb) should use `def_span`. + if let Some(did) = did.as_local() { + let hir_id = self.tcx().hir().local_def_id_to_hir_id(did); + if self.tcx().sess.opts.debugging_opts.span_free_formats { + p!(write("@"), print_def_path(did.to_def_id(), substs)); + } else { + let span = self.tcx().hir().span(hir_id); + p!(write("@{}", self.tcx().sess.source_map().span_to_string(span))); + } + + if substs.as_closure().is_valid() { + let upvar_tys = substs.as_closure().upvar_tys(); + let mut sep = " "; + for (&var_id, upvar_ty) in self + .tcx() + .upvars_mentioned(did) + .as_ref() + .iter() + .flat_map(|v| v.keys()) + .zip(upvar_tys) + { + p!(write("{}{}:", sep, self.tcx().hir().name(var_id)), print(upvar_ty)); + sep = ", "; + } + } + } else { + p!(write("@{}", self.tcx().def_path_str(did))); + + if substs.as_closure().is_valid() { + let upvar_tys = substs.as_closure().upvar_tys(); + let mut sep = " "; + for (index, upvar_ty) in upvar_tys.enumerate() { + p!(write("{}{}:", sep, index), print(upvar_ty)); + sep = ", "; + } + } + } + + if self.tcx().sess.verbose() && substs.as_closure().is_valid() { + p!(write(" closure_kind_ty="), print(substs.as_closure().kind_ty())); + p!( + write(" closure_sig_as_fn_ptr_ty="), + print(substs.as_closure().sig_as_fn_ptr_ty()) + ); + } + + p!(write("]")) + } + ty::Array(ty, sz) => { + p!(write("["), print(ty), write("; ")); + if self.tcx().sess.verbose() { + p!(write("{:?}", sz)); + } else if let ty::ConstKind::Unevaluated(..) = sz.val { + // Do not try to evaluate unevaluated constants. If we are const evaluating an + // array length anon const, rustc will (with debug assertions) print the + // constant's path. Which will end up here again. + p!(write("_")); + } else if let Some(n) = sz.val.try_to_bits(self.tcx().data_layout.pointer_size) { + p!(write("{}", n)); + } else if let ty::ConstKind::Param(param) = sz.val { + p!(write("{}", param)); + } else { + p!(write("_")); + } + p!(write("]")) + } + ty::Slice(ty) => p!(write("["), print(ty), write("]")), + } + + Ok(self) + } + + fn pretty_print_bound_var( + &mut self, + debruijn: ty::DebruijnIndex, + var: ty::BoundVar, + ) -> Result<(), Self::Error> { + if debruijn == ty::INNERMOST { + write!(self, "^{}", var.index()) + } else { + write!(self, "^{}_{}", debruijn.index(), var.index()) + } + } + + fn infer_ty_name(&self, _: ty::TyVid) -> Option<String> { + None + } + + fn pretty_print_dyn_existential( + mut self, + predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>, + ) -> Result<Self::DynExistential, Self::Error> { + define_scoped_cx!(self); + + // Generate the main trait ref, including associated types. + let mut first = true; + + if let Some(principal) = predicates.principal() { + p!(print_def_path(principal.def_id, &[])); + + let mut resugared = false; + + // Special-case `Fn(...) -> ...` and resugar it. + let fn_trait_kind = self.tcx().fn_trait_kind_from_lang_item(principal.def_id); + if !self.tcx().sess.verbose() && fn_trait_kind.is_some() { + if let ty::Tuple(ref args) = principal.substs.type_at(0).kind { + let mut projections = predicates.projection_bounds(); + if let (Some(proj), None) = (projections.next(), projections.next()) { + let tys: Vec<_> = args.iter().map(|k| k.expect_ty()).collect(); + p!(pretty_fn_sig(&tys, false, proj.ty)); + resugared = true; + } + } + } + + // HACK(eddyb) this duplicates `FmtPrinter`'s `path_generic_args`, + // in order to place the projections inside the `<...>`. + if !resugared { + // Use a type that can't appear in defaults of type parameters. + let dummy_self = self.tcx().mk_ty_infer(ty::FreshTy(0)); + let principal = principal.with_self_ty(self.tcx(), dummy_self); + + let args = self.generic_args_to_print( + self.tcx().generics_of(principal.def_id), + principal.substs, + ); + + // Don't print `'_` if there's no unerased regions. + let print_regions = args.iter().any(|arg| match arg.unpack() { + GenericArgKind::Lifetime(r) => *r != ty::ReErased, + _ => false, + }); + let mut args = args.iter().cloned().filter(|arg| match arg.unpack() { + GenericArgKind::Lifetime(_) => print_regions, + _ => true, + }); + let mut projections = predicates.projection_bounds(); + + let arg0 = args.next(); + let projection0 = projections.next(); + if arg0.is_some() || projection0.is_some() { + let args = arg0.into_iter().chain(args); + let projections = projection0.into_iter().chain(projections); + + p!(generic_delimiters(|mut cx| { + cx = cx.comma_sep(args)?; + if arg0.is_some() && projection0.is_some() { + write!(cx, ", ")?; + } + cx.comma_sep(projections) + })); + } + } + first = false; + } + + // Builtin bounds. + // FIXME(eddyb) avoid printing twice (needed to ensure + // that the auto traits are sorted *and* printed via cx). + let mut auto_traits: Vec<_> = + predicates.auto_traits().map(|did| (self.tcx().def_path_str(did), did)).collect(); + + // The auto traits come ordered by `DefPathHash`. While + // `DefPathHash` is *stable* in the sense that it depends on + // neither the host nor the phase of the moon, it depends + // "pseudorandomly" on the compiler version and the target. + // + // To avoid that causing instabilities in compiletest + // output, sort the auto-traits alphabetically. + auto_traits.sort(); + + for (_, def_id) in auto_traits { + if !first { + p!(write(" + ")); + } + first = false; + + p!(print_def_path(def_id, &[])); + } + + Ok(self) + } + + fn pretty_fn_sig( + mut self, + inputs: &[Ty<'tcx>], + c_variadic: bool, + output: Ty<'tcx>, + ) -> Result<Self, Self::Error> { + define_scoped_cx!(self); + + p!(write("("), comma_sep(inputs.iter().copied())); + if c_variadic { + if !inputs.is_empty() { + p!(write(", ")); + } + p!(write("...")); + } + p!(write(")")); + if !output.is_unit() { + p!(write(" -> "), print(output)); + } + + Ok(self) + } + + fn pretty_print_const( + mut self, + ct: &'tcx ty::Const<'tcx>, + print_ty: bool, + ) -> Result<Self::Const, Self::Error> { + define_scoped_cx!(self); + + if self.tcx().sess.verbose() { + p!(write("Const({:?}: {:?})", ct.val, ct.ty)); + return Ok(self); + } + + macro_rules! print_underscore { + () => {{ + if print_ty { + self = self.typed_value( + |mut this| { + write!(this, "_")?; + Ok(this) + }, + |this| this.print_type(ct.ty), + ": ", + )?; + } else { + write!(self, "_")?; + } + }}; + } + + match ct.val { + ty::ConstKind::Unevaluated(def, substs, promoted) => { + if let Some(promoted) = promoted { + p!(print_value_path(def.did, substs)); + p!(write("::{:?}", promoted)); + } else { + match self.tcx().def_kind(def.did) { + DefKind::Static | DefKind::Const | DefKind::AssocConst => { + p!(print_value_path(def.did, substs)) + } + _ => { + if def.is_local() { + let span = self.tcx().def_span(def.did); + if let Ok(snip) = self.tcx().sess.source_map().span_to_snippet(span) + { + p!(write("{}", snip)) + } else { + print_underscore!() + } + } else { + print_underscore!() + } + } + } + } + } + ty::ConstKind::Infer(..) => print_underscore!(), + ty::ConstKind::Param(ParamConst { name, .. }) => p!(write("{}", name)), + ty::ConstKind::Value(value) => { + return self.pretty_print_const_value(value, ct.ty, print_ty); + } + + ty::ConstKind::Bound(debruijn, bound_var) => { + self.pretty_print_bound_var(debruijn, bound_var)? + } + ty::ConstKind::Placeholder(placeholder) => p!(write("Placeholder({:?})", placeholder)), + ty::ConstKind::Error(_) => p!(write("[const error]")), + }; + Ok(self) + } + + fn pretty_print_const_scalar( + mut self, + scalar: Scalar, + ty: Ty<'tcx>, + print_ty: bool, + ) -> Result<Self::Const, Self::Error> { + define_scoped_cx!(self); + + match (scalar, &ty.kind) { + // Byte strings (&[u8; N]) + ( + Scalar::Ptr(ptr), + ty::Ref( + _, + ty::TyS { + kind: + ty::Array( + ty::TyS { kind: ty::Uint(ast::UintTy::U8), .. }, + ty::Const { + val: + ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { + data, + .. + })), + .. + }, + ), + .. + }, + _, + ), + ) => match self.tcx().get_global_alloc(ptr.alloc_id) { + Some(GlobalAlloc::Memory(alloc)) => { + if let Ok(byte_str) = alloc.get_bytes(&self.tcx(), ptr, Size::from_bytes(*data)) + { + p!(pretty_print_byte_str(byte_str)) + } else { + p!(write("<too short allocation>")) + } + } + // FIXME: for statics and functions, we could in principle print more detail. + Some(GlobalAlloc::Static(def_id)) => p!(write("<static({:?})>", def_id)), + Some(GlobalAlloc::Function(_)) => p!(write("<function>")), + None => p!(write("<dangling pointer>")), + }, + // Bool + (Scalar::Raw { data: 0, .. }, ty::Bool) => p!(write("false")), + (Scalar::Raw { data: 1, .. }, ty::Bool) => p!(write("true")), + // Float + (Scalar::Raw { data, .. }, ty::Float(ast::FloatTy::F32)) => { + p!(write("{}f32", Single::from_bits(data))) + } + (Scalar::Raw { data, .. }, ty::Float(ast::FloatTy::F64)) => { + p!(write("{}f64", Double::from_bits(data))) + } + // Int + (Scalar::Raw { data, .. }, ty::Uint(ui)) => { + let size = Integer::from_attr(&self.tcx(), UnsignedInt(*ui)).size(); + let int = ConstInt::new(data, size, false, ty.is_ptr_sized_integral()); + if print_ty { p!(write("{:#?}", int)) } else { p!(write("{:?}", int)) } + } + (Scalar::Raw { data, .. }, ty::Int(i)) => { + let size = Integer::from_attr(&self.tcx(), SignedInt(*i)).size(); + let int = ConstInt::new(data, size, true, ty.is_ptr_sized_integral()); + if print_ty { p!(write("{:#?}", int)) } else { p!(write("{:?}", int)) } + } + // Char + (Scalar::Raw { data, .. }, ty::Char) if char::from_u32(data as u32).is_some() => { + p!(write("{:?}", char::from_u32(data as u32).unwrap())) + } + // Raw pointers + (Scalar::Raw { data, .. }, ty::RawPtr(_)) => { + self = self.typed_value( + |mut this| { + write!(this, "0x{:x}", data)?; + Ok(this) + }, + |this| this.print_type(ty), + " as ", + )?; + } + (Scalar::Ptr(ptr), ty::FnPtr(_)) => { + // FIXME: this can ICE when the ptr is dangling or points to a non-function. + // We should probably have a helper method to share code with the "Byte strings" + // printing above (which also has to handle pointers to all sorts of things). + let instance = self.tcx().global_alloc(ptr.alloc_id).unwrap_fn(); + self = self.typed_value( + |this| this.print_value_path(instance.def_id(), instance.substs), + |this| this.print_type(ty), + " as ", + )?; + } + // For function type zsts just printing the path is enough + (Scalar::Raw { size: 0, .. }, ty::FnDef(d, s)) => p!(print_value_path(*d, s)), + // Nontrivial types with scalar bit representation + (Scalar::Raw { data, size }, _) => { + let print = |mut this: Self| { + if size == 0 { + write!(this, "transmute(())")?; + } else { + write!(this, "transmute(0x{:01$x})", data, size as usize * 2)?; + } + Ok(this) + }; + self = if print_ty { + self.typed_value(print, |this| this.print_type(ty), ": ")? + } else { + print(self)? + }; + } + // Any pointer values not covered by a branch above + (Scalar::Ptr(p), _) => { + self = self.pretty_print_const_pointer(p, ty, print_ty)?; + } + } + Ok(self) + } + + /// This is overridden for MIR printing because we only want to hide alloc ids from users, not + /// from MIR where it is actually useful. + fn pretty_print_const_pointer( + mut self, + _: Pointer, + ty: Ty<'tcx>, + print_ty: bool, + ) -> Result<Self::Const, Self::Error> { + if print_ty { + self.typed_value( + |mut this| { + this.write_str("&_")?; + Ok(this) + }, + |this| this.print_type(ty), + ": ", + ) + } else { + self.write_str("&_")?; + Ok(self) + } + } + + fn pretty_print_byte_str(mut self, byte_str: &'tcx [u8]) -> Result<Self::Const, Self::Error> { + define_scoped_cx!(self); + p!(write("b\"")); + for &c in byte_str { + for e in std::ascii::escape_default(c) { + self.write_char(e as char)?; + } + } + p!(write("\"")); + Ok(self) + } + + fn pretty_print_const_value( + mut self, + ct: ConstValue<'tcx>, + ty: Ty<'tcx>, + print_ty: bool, + ) -> Result<Self::Const, Self::Error> { + define_scoped_cx!(self); + + if self.tcx().sess.verbose() { + p!(write("ConstValue({:?}: ", ct), print(ty), write(")")); + return Ok(self); + } + + let u8_type = self.tcx().types.u8; + + match (ct, &ty.kind) { + // Byte/string slices, printed as (byte) string literals. + ( + ConstValue::Slice { data, start, end }, + ty::Ref(_, ty::TyS { kind: ty::Slice(t), .. }, _), + ) if *t == u8_type => { + // The `inspect` here is okay since we checked the bounds, and there are + // no relocations (we have an active slice reference here). We don't use + // this result to affect interpreter execution. + let byte_str = data.inspect_with_uninit_and_ptr_outside_interpreter(start..end); + self.pretty_print_byte_str(byte_str) + } + ( + ConstValue::Slice { data, start, end }, + ty::Ref(_, ty::TyS { kind: ty::Str, .. }, _), + ) => { + // The `inspect` here is okay since we checked the bounds, and there are no + // relocations (we have an active `str` reference here). We don't use this + // result to affect interpreter execution. + let slice = data.inspect_with_uninit_and_ptr_outside_interpreter(start..end); + let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri"); + p!(write("{:?}", s)); + Ok(self) + } + (ConstValue::ByRef { alloc, offset }, ty::Array(t, n)) if *t == u8_type => { + let n = n.val.try_to_bits(self.tcx().data_layout.pointer_size).unwrap(); + // cast is ok because we already checked for pointer size (32 or 64 bit) above + let n = Size::from_bytes(n); + let ptr = Pointer::new(AllocId(0), offset); + + let byte_str = alloc.get_bytes(&self.tcx(), ptr, n).unwrap(); + p!(write("*")); + p!(pretty_print_byte_str(byte_str)); + Ok(self) + } + + // Aggregates, printed as array/tuple/struct/variant construction syntax. + // + // NB: the `has_param_types_or_consts` check ensures that we can use + // the `destructure_const` query with an empty `ty::ParamEnv` without + // introducing ICEs (e.g. via `layout_of`) from missing bounds. + // E.g. `transmute([0usize; 2]): (u8, *mut T)` needs to know `T: Sized` + // to be able to destructure the tuple into `(0u8, *mut T) + // + // FIXME(eddyb) for `--emit=mir`/`-Z dump-mir`, we should provide the + // correct `ty::ParamEnv` to allow printing *all* constant values. + (_, ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) if !ty.has_param_types_or_consts() => { + let contents = self.tcx().destructure_const( + ty::ParamEnv::reveal_all() + .and(self.tcx().mk_const(ty::Const { val: ty::ConstKind::Value(ct), ty })), + ); + let fields = contents.fields.iter().copied(); + + match ty.kind { + ty::Array(..) => { + p!(write("["), comma_sep(fields), write("]")); + } + ty::Tuple(..) => { + p!(write("("), comma_sep(fields)); + if contents.fields.len() == 1 { + p!(write(",")); + } + p!(write(")")); + } + ty::Adt(def, substs) if def.variants.is_empty() => { + p!(print_value_path(def.did, substs)); + } + ty::Adt(def, substs) => { + let variant_id = + contents.variant.expect("destructed const of adt without variant id"); + let variant_def = &def.variants[variant_id]; + p!(print_value_path(variant_def.def_id, substs)); + + match variant_def.ctor_kind { + CtorKind::Const => {} + CtorKind::Fn => { + p!(write("("), comma_sep(fields), write(")")); + } + CtorKind::Fictive => { + p!(write(" {{ ")); + let mut first = true; + for (field_def, field) in variant_def.fields.iter().zip(fields) { + if !first { + p!(write(", ")); + } + p!(write("{}: ", field_def.ident), print(field)); + first = false; + } + p!(write(" }}")); + } + } + } + _ => unreachable!(), + } + + Ok(self) + } + + (ConstValue::Scalar(scalar), _) => self.pretty_print_const_scalar(scalar, ty, print_ty), + + // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading + // their fields instead of just dumping the memory. + _ => { + // fallback + p!(write("{:?}", ct)); + if print_ty { + p!(write(": "), print(ty)); + } + Ok(self) + } + } + } +} + +// HACK(eddyb) boxed to avoid moving around a large struct by-value. +pub struct FmtPrinter<'a, 'tcx, F>(Box<FmtPrinterData<'a, 'tcx, F>>); + +pub struct FmtPrinterData<'a, 'tcx, F> { + tcx: TyCtxt<'tcx>, + fmt: F, + + empty_path: bool, + in_value: bool, + pub print_alloc_ids: bool, + + used_region_names: FxHashSet<Symbol>, + region_index: usize, + binder_depth: usize, + + pub region_highlight_mode: RegionHighlightMode, + + pub name_resolver: Option<Box<&'a dyn Fn(ty::sty::TyVid) -> Option<String>>>, +} + +impl<F> Deref for FmtPrinter<'a, 'tcx, F> { + type Target = FmtPrinterData<'a, 'tcx, F>; + fn deref(&self) -> &Self::Target { + &self.0 + } +} + +impl<F> DerefMut for FmtPrinter<'_, '_, F> { + fn deref_mut(&mut self) -> &mut Self::Target { + &mut self.0 + } +} + +impl<F> FmtPrinter<'a, 'tcx, F> { + pub fn new(tcx: TyCtxt<'tcx>, fmt: F, ns: Namespace) -> Self { + FmtPrinter(Box::new(FmtPrinterData { + tcx, + fmt, + empty_path: false, + in_value: ns == Namespace::ValueNS, + print_alloc_ids: false, + used_region_names: Default::default(), + region_index: 0, + binder_depth: 0, + region_highlight_mode: RegionHighlightMode::default(), + name_resolver: None, + })) + } +} + +// HACK(eddyb) get rid of `def_path_str` and/or pass `Namespace` explicitly always +// (but also some things just print a `DefId` generally so maybe we need this?) +fn guess_def_namespace(tcx: TyCtxt<'_>, def_id: DefId) -> Namespace { + match tcx.def_key(def_id).disambiguated_data.data { + DefPathData::TypeNs(..) | DefPathData::CrateRoot | DefPathData::ImplTrait => { + Namespace::TypeNS + } + + DefPathData::ValueNs(..) + | DefPathData::AnonConst + | DefPathData::ClosureExpr + | DefPathData::Ctor => Namespace::ValueNS, + + DefPathData::MacroNs(..) => Namespace::MacroNS, + + _ => Namespace::TypeNS, + } +} + +impl TyCtxt<'t> { + /// Returns a string identifying this `DefId`. This string is + /// suitable for user output. + pub fn def_path_str(self, def_id: DefId) -> String { + self.def_path_str_with_substs(def_id, &[]) + } + + pub fn def_path_str_with_substs(self, def_id: DefId, substs: &'t [GenericArg<'t>]) -> String { + let ns = guess_def_namespace(self, def_id); + debug!("def_path_str: def_id={:?}, ns={:?}", def_id, ns); + let mut s = String::new(); + let _ = FmtPrinter::new(self, &mut s, ns).print_def_path(def_id, substs); + s + } +} + +impl<F: fmt::Write> fmt::Write for FmtPrinter<'_, '_, F> { + fn write_str(&mut self, s: &str) -> fmt::Result { + self.fmt.write_str(s) + } +} + +impl<F: fmt::Write> Printer<'tcx> for FmtPrinter<'_, 'tcx, F> { + type Error = fmt::Error; + + type Path = Self; + type Region = Self; + type Type = Self; + type DynExistential = Self; + type Const = Self; + + fn tcx(&'a self) -> TyCtxt<'tcx> { + self.tcx + } + + fn print_def_path( + mut self, + def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error> { + define_scoped_cx!(self); + + if substs.is_empty() { + match self.try_print_visible_def_path(def_id)? { + (cx, true) => return Ok(cx), + (cx, false) => self = cx, + } + } + + let key = self.tcx.def_key(def_id); + if let DefPathData::Impl = key.disambiguated_data.data { + // Always use types for non-local impls, where types are always + // available, and filename/line-number is mostly uninteresting. + let use_types = !def_id.is_local() || { + // Otherwise, use filename/line-number if forced. + let force_no_types = FORCE_IMPL_FILENAME_LINE.with(|f| f.get()); + !force_no_types + }; + + if !use_types { + // If no type info is available, fall back to + // pretty printing some span information. This should + // only occur very early in the compiler pipeline. + let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id }; + let span = self.tcx.def_span(def_id); + + self = self.print_def_path(parent_def_id, &[])?; + + // HACK(eddyb) copy of `path_append` to avoid + // constructing a `DisambiguatedDefPathData`. + if !self.empty_path { + write!(self, "::")?; + } + write!(self, "<impl at {}>", self.tcx.sess.source_map().span_to_string(span))?; + self.empty_path = false; + + return Ok(self); + } + } + + self.default_print_def_path(def_id, substs) + } + + fn print_region(self, region: ty::Region<'_>) -> Result<Self::Region, Self::Error> { + self.pretty_print_region(region) + } + + fn print_type(self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> { + self.pretty_print_type(ty) + } + + fn print_dyn_existential( + self, + predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>, + ) -> Result<Self::DynExistential, Self::Error> { + self.pretty_print_dyn_existential(predicates) + } + + fn print_const(self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> { + self.pretty_print_const(ct, true) + } + + fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> { + self.empty_path = true; + if cnum == LOCAL_CRATE { + if self.tcx.sess.rust_2018() { + // We add the `crate::` keyword on Rust 2018, only when desired. + if SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get()) { + write!(self, "{}", kw::Crate)?; + self.empty_path = false; + } + } + } else { + write!(self, "{}", self.tcx.crate_name(cnum))?; + self.empty_path = false; + } + Ok(self) + } + + fn path_qualified( + mut self, + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error> { + self = self.pretty_path_qualified(self_ty, trait_ref)?; + self.empty_path = false; + Ok(self) + } + + fn path_append_impl( + mut self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + _disambiguated_data: &DisambiguatedDefPathData, + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error> { + self = self.pretty_path_append_impl( + |mut cx| { + cx = print_prefix(cx)?; + if !cx.empty_path { + write!(cx, "::")?; + } + + Ok(cx) + }, + self_ty, + trait_ref, + )?; + self.empty_path = false; + Ok(self) + } + + fn path_append( + mut self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + disambiguated_data: &DisambiguatedDefPathData, + ) -> Result<Self::Path, Self::Error> { + self = print_prefix(self)?; + + // Skip `::{{constructor}}` on tuple/unit structs. + if let DefPathData::Ctor = disambiguated_data.data { + return Ok(self); + } + + // FIXME(eddyb) `name` should never be empty, but it + // currently is for `extern { ... }` "foreign modules". + let name = disambiguated_data.data.as_symbol(); + if name != kw::Invalid { + if !self.empty_path { + write!(self, "::")?; + } + if Ident::with_dummy_span(name).is_raw_guess() { + write!(self, "r#")?; + } + write!(self, "{}", name)?; + + // FIXME(eddyb) this will print e.g. `{{closure}}#3`, but it + // might be nicer to use something else, e.g. `{closure#3}`. + let dis = disambiguated_data.disambiguator; + let print_dis = disambiguated_data.data.get_opt_name().is_none() + || dis != 0 && self.tcx.sess.verbose(); + if print_dis { + write!(self, "#{}", dis)?; + } + + self.empty_path = false; + } + + Ok(self) + } + + fn path_generic_args( + mut self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + args: &[GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error> { + self = print_prefix(self)?; + + // Don't print `'_` if there's no unerased regions. + let print_regions = args.iter().any(|arg| match arg.unpack() { + GenericArgKind::Lifetime(r) => *r != ty::ReErased, + _ => false, + }); + let args = args.iter().cloned().filter(|arg| match arg.unpack() { + GenericArgKind::Lifetime(_) => print_regions, + _ => true, + }); + + if args.clone().next().is_some() { + if self.in_value { + write!(self, "::")?; + } + self.generic_delimiters(|cx| cx.comma_sep(args)) + } else { + Ok(self) + } + } +} + +impl<F: fmt::Write> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx, F> { + fn infer_ty_name(&self, id: ty::TyVid) -> Option<String> { + self.0.name_resolver.as_ref().and_then(|func| func(id)) + } + + fn print_value_path( + mut self, + def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error> { + let was_in_value = std::mem::replace(&mut self.in_value, true); + self = self.print_def_path(def_id, substs)?; + self.in_value = was_in_value; + + Ok(self) + } + + fn in_binder<T>(self, value: &ty::Binder<T>) -> Result<Self, Self::Error> + where + T: Print<'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>, + { + self.pretty_in_binder(value) + } + + fn typed_value( + mut self, + f: impl FnOnce(Self) -> Result<Self, Self::Error>, + t: impl FnOnce(Self) -> Result<Self, Self::Error>, + conversion: &str, + ) -> Result<Self::Const, Self::Error> { + self.write_str("{")?; + self = f(self)?; + self.write_str(conversion)?; + let was_in_value = std::mem::replace(&mut self.in_value, false); + self = t(self)?; + self.in_value = was_in_value; + self.write_str("}")?; + Ok(self) + } + + fn generic_delimiters( + mut self, + f: impl FnOnce(Self) -> Result<Self, Self::Error>, + ) -> Result<Self, Self::Error> { + write!(self, "<")?; + + let was_in_value = std::mem::replace(&mut self.in_value, false); + let mut inner = f(self)?; + inner.in_value = was_in_value; + + write!(inner, ">")?; + Ok(inner) + } + + fn region_should_not_be_omitted(&self, region: ty::Region<'_>) -> bool { + let highlight = self.region_highlight_mode; + if highlight.region_highlighted(region).is_some() { + return true; + } + + if self.tcx.sess.verbose() { + return true; + } + + let identify_regions = self.tcx.sess.opts.debugging_opts.identify_regions; + + match *region { + ty::ReEarlyBound(ref data) => { + data.name != kw::Invalid && data.name != kw::UnderscoreLifetime + } + + ty::ReLateBound(_, br) + | ty::ReFree(ty::FreeRegion { bound_region: br, .. }) + | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => { + if let ty::BrNamed(_, name) = br { + if name != kw::Invalid && name != kw::UnderscoreLifetime { + return true; + } + } + + if let Some((region, _)) = highlight.highlight_bound_region { + if br == region { + return true; + } + } + + false + } + + ty::ReVar(_) if identify_regions => true, + + ty::ReVar(_) | ty::ReErased => false, + + ty::ReStatic | ty::ReEmpty(_) => true, + } + } + + fn pretty_print_const_pointer( + self, + p: Pointer, + ty: Ty<'tcx>, + print_ty: bool, + ) -> Result<Self::Const, Self::Error> { + let print = |mut this: Self| { + define_scoped_cx!(this); + if this.print_alloc_ids { + p!(write("{:?}", p)); + } else { + p!(write("&_")); + } + Ok(this) + }; + if print_ty { + self.typed_value(print, |this| this.print_type(ty), ": ") + } else { + print(self) + } + } +} + +// HACK(eddyb) limited to `FmtPrinter` because of `region_highlight_mode`. +impl<F: fmt::Write> FmtPrinter<'_, '_, F> { + pub fn pretty_print_region(mut self, region: ty::Region<'_>) -> Result<Self, fmt::Error> { + define_scoped_cx!(self); + + // Watch out for region highlights. + let highlight = self.region_highlight_mode; + if let Some(n) = highlight.region_highlighted(region) { + p!(write("'{}", n)); + return Ok(self); + } + + if self.tcx.sess.verbose() { + p!(write("{:?}", region)); + return Ok(self); + } + + let identify_regions = self.tcx.sess.opts.debugging_opts.identify_regions; + + // These printouts are concise. They do not contain all the information + // the user might want to diagnose an error, but there is basically no way + // to fit that into a short string. Hence the recommendation to use + // `explain_region()` or `note_and_explain_region()`. + match *region { + ty::ReEarlyBound(ref data) => { + if data.name != kw::Invalid { + p!(write("{}", data.name)); + return Ok(self); + } + } + ty::ReLateBound(_, br) + | ty::ReFree(ty::FreeRegion { bound_region: br, .. }) + | ty::RePlaceholder(ty::Placeholder { name: br, .. }) => { + if let ty::BrNamed(_, name) = br { + if name != kw::Invalid && name != kw::UnderscoreLifetime { + p!(write("{}", name)); + return Ok(self); + } + } + + if let Some((region, counter)) = highlight.highlight_bound_region { + if br == region { + p!(write("'{}", counter)); + return Ok(self); + } + } + } + ty::ReVar(region_vid) if identify_regions => { + p!(write("{:?}", region_vid)); + return Ok(self); + } + ty::ReVar(_) => {} + ty::ReErased => {} + ty::ReStatic => { + p!(write("'static")); + return Ok(self); + } + ty::ReEmpty(ty::UniverseIndex::ROOT) => { + p!(write("'<empty>")); + return Ok(self); + } + ty::ReEmpty(ui) => { + p!(write("'<empty:{:?}>", ui)); + return Ok(self); + } + } + + p!(write("'_")); + + Ok(self) + } +} + +// HACK(eddyb) limited to `FmtPrinter` because of `binder_depth`, +// `region_index` and `used_region_names`. +impl<F: fmt::Write> FmtPrinter<'_, 'tcx, F> { + pub fn name_all_regions<T>( + mut self, + value: &ty::Binder<T>, + ) -> Result<(Self, (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>)), fmt::Error> + where + T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>, + { + fn name_by_region_index(index: usize) -> Symbol { + match index { + 0 => Symbol::intern("'r"), + 1 => Symbol::intern("'s"), + i => Symbol::intern(&format!("'t{}", i - 2)), + } + } + + // Replace any anonymous late-bound regions with named + // variants, using new unique identifiers, so that we can + // clearly differentiate between named and unnamed regions in + // the output. We'll probably want to tweak this over time to + // decide just how much information to give. + if self.binder_depth == 0 { + self.prepare_late_bound_region_info(value); + } + + let mut empty = true; + let mut start_or_continue = |cx: &mut Self, start: &str, cont: &str| { + write!( + cx, + "{}", + if empty { + empty = false; + start + } else { + cont + } + ) + }; + + define_scoped_cx!(self); + + let mut region_index = self.region_index; + let new_value = self.tcx.replace_late_bound_regions(value, |br| { + let _ = start_or_continue(&mut self, "for<", ", "); + let br = match br { + ty::BrNamed(_, name) => { + let _ = write!(self, "{}", name); + br + } + ty::BrAnon(_) | ty::BrEnv => { + let name = loop { + let name = name_by_region_index(region_index); + region_index += 1; + if !self.used_region_names.contains(&name) { + break name; + } + }; + let _ = write!(self, "{}", name); + ty::BrNamed(DefId::local(CRATE_DEF_INDEX), name) + } + }; + self.tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)) + }); + start_or_continue(&mut self, "", "> ")?; + + self.binder_depth += 1; + self.region_index = region_index; + Ok((self, new_value)) + } + + pub fn pretty_in_binder<T>(self, value: &ty::Binder<T>) -> Result<Self, fmt::Error> + where + T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>, + { + let old_region_index = self.region_index; + let (new, new_value) = self.name_all_regions(value)?; + let mut inner = new_value.0.print(new)?; + inner.region_index = old_region_index; + inner.binder_depth -= 1; + Ok(inner) + } + + fn prepare_late_bound_region_info<T>(&mut self, value: &ty::Binder<T>) + where + T: TypeFoldable<'tcx>, + { + struct LateBoundRegionNameCollector<'a>(&'a mut FxHashSet<Symbol>); + impl<'tcx> ty::fold::TypeVisitor<'tcx> for LateBoundRegionNameCollector<'_> { + fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool { + if let ty::ReLateBound(_, ty::BrNamed(_, name)) = *r { + self.0.insert(name); + } + r.super_visit_with(self) + } + } + + self.used_region_names.clear(); + let mut collector = LateBoundRegionNameCollector(&mut self.used_region_names); + value.visit_with(&mut collector); + self.region_index = 0; + } +} + +impl<'tcx, T, P: PrettyPrinter<'tcx>> Print<'tcx, P> for ty::Binder<T> +where + T: Print<'tcx, P, Output = P, Error = P::Error> + TypeFoldable<'tcx>, +{ + type Output = P; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.in_binder(self) + } +} + +impl<'tcx, T, U, P: PrettyPrinter<'tcx>> Print<'tcx, P> for ty::OutlivesPredicate<T, U> +where + T: Print<'tcx, P, Output = P, Error = P::Error>, + U: Print<'tcx, P, Output = P, Error = P::Error>, +{ + type Output = P; + type Error = P::Error; + fn print(&self, mut cx: P) -> Result<Self::Output, Self::Error> { + define_scoped_cx!(cx); + p!(print(self.0), write(": "), print(self.1)); + Ok(cx) + } +} + +macro_rules! forward_display_to_print { + ($($ty:ty),+) => { + $(impl fmt::Display for $ty { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + ty::tls::with(|tcx| { + tcx.lift(self) + .expect("could not lift for printing") + .print(FmtPrinter::new(tcx, f, Namespace::TypeNS))?; + Ok(()) + }) + } + })+ + }; +} + +macro_rules! define_print_and_forward_display { + (($self:ident, $cx:ident): $($ty:ty $print:block)+) => { + $(impl<'tcx, P: PrettyPrinter<'tcx>> Print<'tcx, P> for $ty { + type Output = P; + type Error = fmt::Error; + fn print(&$self, $cx: P) -> Result<Self::Output, Self::Error> { + #[allow(unused_mut)] + let mut $cx = $cx; + define_scoped_cx!($cx); + let _: () = $print; + #[allow(unreachable_code)] + Ok($cx) + } + })+ + + forward_display_to_print!($($ty),+); + }; +} + +// HACK(eddyb) this is separate because `ty::RegionKind` doesn't need lifting. +impl fmt::Display for ty::RegionKind { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + ty::tls::with(|tcx| { + self.print(FmtPrinter::new(tcx, f, Namespace::TypeNS))?; + Ok(()) + }) + } +} + +/// Wrapper type for `ty::TraitRef` which opts-in to pretty printing only +/// the trait path. That is, it will print `Trait<U>` instead of +/// `<T as Trait<U>>`. +#[derive(Copy, Clone, TypeFoldable, Lift)] +pub struct TraitRefPrintOnlyTraitPath<'tcx>(ty::TraitRef<'tcx>); + +impl fmt::Debug for TraitRefPrintOnlyTraitPath<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(self, f) + } +} + +impl ty::TraitRef<'tcx> { + pub fn print_only_trait_path(self) -> TraitRefPrintOnlyTraitPath<'tcx> { + TraitRefPrintOnlyTraitPath(self) + } +} + +impl ty::Binder<ty::TraitRef<'tcx>> { + pub fn print_only_trait_path(self) -> ty::Binder<TraitRefPrintOnlyTraitPath<'tcx>> { + self.map_bound(|tr| tr.print_only_trait_path()) + } +} + +forward_display_to_print! { + Ty<'tcx>, + &'tcx ty::List<ty::ExistentialPredicate<'tcx>>, + &'tcx ty::Const<'tcx>, + + // HACK(eddyb) these are exhaustive instead of generic, + // because `for<'tcx>` isn't possible yet. + ty::Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>, + ty::Binder<ty::TraitRef<'tcx>>, + ty::Binder<TraitRefPrintOnlyTraitPath<'tcx>>, + ty::Binder<ty::FnSig<'tcx>>, + ty::Binder<ty::TraitPredicate<'tcx>>, + ty::Binder<ty::SubtypePredicate<'tcx>>, + ty::Binder<ty::ProjectionPredicate<'tcx>>, + ty::Binder<ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>>, + ty::Binder<ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>>, + + ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>, + ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>> +} + +define_print_and_forward_display! { + (self, cx): + + &'tcx ty::List<Ty<'tcx>> { + p!(write("{{"), comma_sep(self.iter()), write("}}")) + } + + ty::TypeAndMut<'tcx> { + p!(write("{}", self.mutbl.prefix_str()), print(self.ty)) + } + + ty::ExistentialTraitRef<'tcx> { + // Use a type that can't appear in defaults of type parameters. + let dummy_self = cx.tcx().mk_ty_infer(ty::FreshTy(0)); + let trait_ref = self.with_self_ty(cx.tcx(), dummy_self); + p!(print(trait_ref.print_only_trait_path())) + } + + ty::ExistentialProjection<'tcx> { + let name = cx.tcx().associated_item(self.item_def_id).ident; + p!(write("{} = ", name), print(self.ty)) + } + + ty::ExistentialPredicate<'tcx> { + match *self { + ty::ExistentialPredicate::Trait(x) => p!(print(x)), + ty::ExistentialPredicate::Projection(x) => p!(print(x)), + ty::ExistentialPredicate::AutoTrait(def_id) => { + p!(print_def_path(def_id, &[])); + } + } + } + + ty::FnSig<'tcx> { + p!(write("{}", self.unsafety.prefix_str())); + + if self.abi != Abi::Rust { + p!(write("extern {} ", self.abi)); + } + + p!(write("fn"), pretty_fn_sig(self.inputs(), self.c_variadic, self.output())); + } + + ty::InferTy { + if cx.tcx().sess.verbose() { + p!(write("{:?}", self)); + return Ok(cx); + } + match *self { + ty::TyVar(_) => p!(write("_")), + ty::IntVar(_) => p!(write("{}", "{integer}")), + ty::FloatVar(_) => p!(write("{}", "{float}")), + ty::FreshTy(v) => p!(write("FreshTy({})", v)), + ty::FreshIntTy(v) => p!(write("FreshIntTy({})", v)), + ty::FreshFloatTy(v) => p!(write("FreshFloatTy({})", v)) + } + } + + ty::TraitRef<'tcx> { + p!(write("<{} as {}>", self.self_ty(), self.print_only_trait_path())) + } + + TraitRefPrintOnlyTraitPath<'tcx> { + p!(print_def_path(self.0.def_id, self.0.substs)); + } + + ty::ParamTy { + p!(write("{}", self.name)) + } + + ty::ParamConst { + p!(write("{}", self.name)) + } + + ty::SubtypePredicate<'tcx> { + p!(print(self.a), write(" <: "), print(self.b)) + } + + ty::TraitPredicate<'tcx> { + p!(print(self.trait_ref.self_ty()), write(": "), + print(self.trait_ref.print_only_trait_path())) + } + + ty::ProjectionPredicate<'tcx> { + p!(print(self.projection_ty), write(" == "), print(self.ty)) + } + + ty::ProjectionTy<'tcx> { + p!(print_def_path(self.item_def_id, self.substs)); + } + + ty::ClosureKind { + match *self { + ty::ClosureKind::Fn => p!(write("Fn")), + ty::ClosureKind::FnMut => p!(write("FnMut")), + ty::ClosureKind::FnOnce => p!(write("FnOnce")), + } + } + + ty::Predicate<'tcx> { + match self.kind() { + &ty::PredicateKind::Atom(atom) => p!(print(atom)), + ty::PredicateKind::ForAll(binder) => p!(print(binder)), + } + } + + ty::PredicateAtom<'tcx> { + match *self { + ty::PredicateAtom::Trait(ref data, constness) => { + if let hir::Constness::Const = constness { + p!(write("const ")); + } + p!(print(data)) + } + ty::PredicateAtom::Subtype(predicate) => p!(print(predicate)), + ty::PredicateAtom::RegionOutlives(predicate) => p!(print(predicate)), + ty::PredicateAtom::TypeOutlives(predicate) => p!(print(predicate)), + ty::PredicateAtom::Projection(predicate) => p!(print(predicate)), + ty::PredicateAtom::WellFormed(arg) => p!(print(arg), write(" well-formed")), + ty::PredicateAtom::ObjectSafe(trait_def_id) => { + p!(write("the trait `"), + print_def_path(trait_def_id, &[]), + write("` is object-safe")) + } + ty::PredicateAtom::ClosureKind(closure_def_id, _closure_substs, kind) => { + p!(write("the closure `"), + print_value_path(closure_def_id, &[]), + write("` implements the trait `{}`", kind)) + } + ty::PredicateAtom::ConstEvaluatable(def, substs) => { + p!(write("the constant `"), + print_value_path(def.did, substs), + write("` can be evaluated")) + } + ty::PredicateAtom::ConstEquate(c1, c2) => { + p!(write("the constant `"), + print(c1), + write("` equals `"), + print(c2), + write("`")) + } + } + } + + GenericArg<'tcx> { + match self.unpack() { + GenericArgKind::Lifetime(lt) => p!(print(lt)), + GenericArgKind::Type(ty) => p!(print(ty)), + GenericArgKind::Const(ct) => p!(print(ct)), + } + } +} diff --git a/compiler/rustc_middle/src/ty/query/README.md b/compiler/rustc_middle/src/ty/query/README.md new file mode 100644 index 00000000000..8ec07b9fdeb --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/README.md @@ -0,0 +1,3 @@ +For more information about how the query system works, see the [rustc dev guide]. + +[rustc dev guide]: https://rustc-dev-guide.rust-lang.org/query.html diff --git a/compiler/rustc_middle/src/ty/query/job.rs b/compiler/rustc_middle/src/ty/query/job.rs new file mode 100644 index 00000000000..bd2e7747b7d --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/job.rs @@ -0,0 +1,26 @@ +use crate::ty::tls; + +use rustc_query_system::query::deadlock; +use rustc_rayon_core as rayon_core; +use std::thread; + +/// Creates a new thread and forwards information in thread locals to it. +/// The new thread runs the deadlock handler. +/// Must only be called when a deadlock is about to happen. +pub unsafe fn handle_deadlock() { + let registry = rayon_core::Registry::current(); + + let context = tls::get_tlv(); + assert!(context != 0); + rustc_data_structures::sync::assert_sync::<tls::ImplicitCtxt<'_, '_>>(); + let icx: &tls::ImplicitCtxt<'_, '_> = &*(context as *const tls::ImplicitCtxt<'_, '_>); + + let session_globals = rustc_span::SESSION_GLOBALS.with(|sg| sg as *const _); + let session_globals = &*session_globals; + thread::spawn(move || { + tls::enter_context(icx, |_| { + rustc_span::SESSION_GLOBALS + .set(session_globals, || tls::with(|tcx| deadlock(tcx, ®istry))) + }) + }); +} diff --git a/compiler/rustc_middle/src/ty/query/keys.rs b/compiler/rustc_middle/src/ty/query/keys.rs new file mode 100644 index 00000000000..3f7a20bba2b --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/keys.rs @@ -0,0 +1,353 @@ +//! Defines the set of legal keys that can be used in queries. + +use crate::infer::canonical::Canonical; +use crate::mir; +use crate::ty::fast_reject::SimplifiedType; +use crate::ty::subst::{GenericArg, SubstsRef}; +use crate::ty::{self, Ty, TyCtxt}; +use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE}; +use rustc_query_system::query::DefaultCacheSelector; +use rustc_span::symbol::Symbol; +use rustc_span::{Span, DUMMY_SP}; + +/// The `Key` trait controls what types can legally be used as the key +/// for a query. +pub trait Key { + type CacheSelector; + + /// Given an instance of this key, what crate is it referring to? + /// This is used to find the provider. + fn query_crate(&self) -> CrateNum; + + /// In the event that a cycle occurs, if no explicit span has been + /// given for a query with key `self`, what span should we use? + fn default_span(&self, tcx: TyCtxt<'_>) -> Span; +} + +impl<'tcx> Key for ty::InstanceDef<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + tcx.def_span(self.def_id()) + } +} + +impl<'tcx> Key for ty::Instance<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + tcx.def_span(self.def_id()) + } +} + +impl<'tcx> Key for mir::interpret::GlobalId<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.instance.query_crate() + } + + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.instance.default_span(tcx) + } +} + +impl<'tcx> Key for mir::interpret::LitToConstInput<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + + fn default_span(&self, _tcx: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl Key for CrateNum { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + *self + } + fn default_span(&self, _: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl Key for LocalDefId { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.to_def_id().query_crate() + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.to_def_id().default_span(tcx) + } +} + +impl Key for DefId { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.krate + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + tcx.def_span(*self) + } +} + +impl Key for ty::WithOptConstParam<LocalDefId> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.did.query_crate() + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.did.default_span(tcx) + } +} + +impl Key for (DefId, DefId) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.0.krate + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.1.default_span(tcx) + } +} + +impl Key for (DefId, LocalDefId) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.0.krate + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.1.default_span(tcx) + } +} + +impl Key for (LocalDefId, DefId) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.0.default_span(tcx) + } +} + +impl Key for (CrateNum, DefId) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.0 + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.1.default_span(tcx) + } +} + +impl Key for (DefId, SimplifiedType) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.0.krate + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.0.default_span(tcx) + } +} + +impl<'tcx> Key for SubstsRef<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, _: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl<'tcx> Key for (DefId, SubstsRef<'tcx>) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.0.krate + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.0.default_span(tcx) + } +} + +impl<'tcx> Key for (LocalDefId, DefId, SubstsRef<'tcx>) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.0.default_span(tcx) + } +} + +impl<'tcx> Key for (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.1.def_id().krate + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + tcx.def_span(self.1.def_id()) + } +} + +impl<'tcx> Key for (&'tcx ty::Const<'tcx>, mir::Field) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, _: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl<'tcx> Key for ty::PolyTraitRef<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.def_id().krate + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + tcx.def_span(self.def_id()) + } +} + +impl<'tcx> Key for GenericArg<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, _: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl<'tcx> Key for &'tcx ty::Const<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, _: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl<'tcx> Key for Ty<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, _: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl<'tcx> Key for &'tcx ty::List<ty::Predicate<'tcx>> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, _: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl<'tcx> Key for ty::ParamEnv<'tcx> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, _: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl<'tcx, T: Key> Key for ty::ParamEnvAnd<'tcx, T> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + self.value.query_crate() + } + fn default_span(&self, tcx: TyCtxt<'_>) -> Span { + self.value.default_span(tcx) + } +} + +impl Key for Symbol { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + fn default_span(&self, _tcx: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +/// Canonical query goals correspond to abstract trait operations that +/// are not tied to any crate in particular. +impl<'tcx, T> Key for Canonical<'tcx, T> { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + + fn default_span(&self, _tcx: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl Key for (Symbol, u32, u32) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + + fn default_span(&self, _tcx: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} + +impl<'tcx> Key for (DefId, Ty<'tcx>, SubstsRef<'tcx>, ty::ParamEnv<'tcx>) { + type CacheSelector = DefaultCacheSelector; + + fn query_crate(&self) -> CrateNum { + LOCAL_CRATE + } + + fn default_span(&self, _tcx: TyCtxt<'_>) -> Span { + DUMMY_SP + } +} diff --git a/compiler/rustc_middle/src/ty/query/mod.rs b/compiler/rustc_middle/src/ty/query/mod.rs new file mode 100644 index 00000000000..ee9b203b151 --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/mod.rs @@ -0,0 +1,220 @@ +use crate::dep_graph::{self, DepKind, DepNode, DepNodeParams}; +use crate::hir::exports::Export; +use crate::hir::map; +use crate::infer::canonical::{self, Canonical}; +use crate::lint::LintLevelMap; +use crate::middle::codegen_fn_attrs::CodegenFnAttrs; +use crate::middle::cstore::{CrateDepKind, CrateSource}; +use crate::middle::cstore::{ExternCrate, ForeignModule, LinkagePreference, NativeLib}; +use crate::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel}; +use crate::middle::lib_features::LibFeatures; +use crate::middle::privacy::AccessLevels; +use crate::middle::region; +use crate::middle::resolve_lifetime::{ObjectLifetimeDefault, Region, ResolveLifetimes}; +use crate::middle::stability::{self, DeprecationEntry}; +use crate::mir; +use crate::mir::interpret::GlobalId; +use crate::mir::interpret::{ConstEvalRawResult, ConstEvalResult, ConstValue}; +use crate::mir::interpret::{LitToConstError, LitToConstInput}; +use crate::mir::mono::CodegenUnit; +use crate::traits::query::{ + CanonicalPredicateGoal, CanonicalProjectionGoal, CanonicalTyGoal, + CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal, + CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpSubtypeGoal, NoSolution, +}; +use crate::traits::query::{ + DropckOutlivesResult, DtorckConstraint, MethodAutoderefStepsResult, NormalizationResult, + OutlivesBound, +}; +use crate::traits::specialization_graph; +use crate::traits::{self, ImplSource}; +use crate::ty::steal::Steal; +use crate::ty::subst::{GenericArg, SubstsRef}; +use crate::ty::util::AlwaysRequiresDrop; +use crate::ty::{self, AdtSizedConstraint, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt}; +use rustc_data_structures::fingerprint::Fingerprint; +use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap}; +use rustc_data_structures::profiling::ProfileCategory::*; +use rustc_data_structures::stable_hasher::StableVec; +use rustc_data_structures::svh::Svh; +use rustc_data_structures::sync::Lrc; +use rustc_errors::ErrorReported; +use rustc_hir as hir; +use rustc_hir::def::DefKind; +use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIdSet, LocalDefId}; +use rustc_hir::lang_items::{LangItem, LanguageItems}; +use rustc_hir::{Crate, ItemLocalId, TraitCandidate}; +use rustc_index::{bit_set::FiniteBitSet, vec::IndexVec}; +use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion}; +use rustc_session::utils::NativeLibKind; +use rustc_session::CrateDisambiguator; +use rustc_target::spec::PanicStrategy; + +use rustc_ast as ast; +use rustc_attr as attr; +use rustc_span::symbol::Symbol; +use rustc_span::{Span, DUMMY_SP}; +use std::borrow::Cow; +use std::collections::BTreeMap; +use std::ops::Deref; +use std::path::PathBuf; +use std::sync::Arc; + +#[macro_use] +mod plumbing; +pub(crate) use rustc_query_system::query::CycleError; +use rustc_query_system::query::*; + +mod stats; +pub use self::stats::print_stats; + +#[cfg(parallel_compiler)] +mod job; +#[cfg(parallel_compiler)] +pub use self::job::handle_deadlock; +pub use rustc_query_system::query::{QueryInfo, QueryJob, QueryJobId}; + +mod keys; +use self::keys::Key; + +mod values; +use self::values::Value; + +use rustc_query_system::query::QueryAccessors; +pub use rustc_query_system::query::QueryConfig; +pub(crate) use rustc_query_system::query::QueryDescription; + +mod on_disk_cache; +pub use self::on_disk_cache::OnDiskCache; + +mod profiling_support; +pub use self::profiling_support::{IntoSelfProfilingString, QueryKeyStringBuilder}; + +// Each of these queries corresponds to a function pointer field in the +// `Providers` struct for requesting a value of that type, and a method +// on `tcx: TyCtxt` (and `tcx.at(span)`) for doing that request in a way +// which memoizes and does dep-graph tracking, wrapping around the actual +// `Providers` that the driver creates (using several `rustc_*` crates). +// +// The result type of each query must implement `Clone`, and additionally +// `ty::query::values::Value`, which produces an appropriate placeholder +// (error) value if the query resulted in a query cycle. +// Queries marked with `fatal_cycle` do not need the latter implementation, +// as they will raise an fatal error on query cycles instead. + +rustc_query_append! { [define_queries!][<'tcx>] } + +/// The red/green evaluation system will try to mark a specific DepNode in the +/// dependency graph as green by recursively trying to mark the dependencies of +/// that `DepNode` as green. While doing so, it will sometimes encounter a `DepNode` +/// where we don't know if it is red or green and we therefore actually have +/// to recompute its value in order to find out. Since the only piece of +/// information that we have at that point is the `DepNode` we are trying to +/// re-evaluate, we need some way to re-run a query from just that. This is what +/// `force_from_dep_node()` implements. +/// +/// In the general case, a `DepNode` consists of a `DepKind` and an opaque +/// GUID/fingerprint that will uniquely identify the node. This GUID/fingerprint +/// is usually constructed by computing a stable hash of the query-key that the +/// `DepNode` corresponds to. Consequently, it is not in general possible to go +/// back from hash to query-key (since hash functions are not reversible). For +/// this reason `force_from_dep_node()` is expected to fail from time to time +/// because we just cannot find out, from the `DepNode` alone, what the +/// corresponding query-key is and therefore cannot re-run the query. +/// +/// The system deals with this case letting `try_mark_green` fail which forces +/// the root query to be re-evaluated. +/// +/// Now, if `force_from_dep_node()` would always fail, it would be pretty useless. +/// Fortunately, we can use some contextual information that will allow us to +/// reconstruct query-keys for certain kinds of `DepNode`s. In particular, we +/// enforce by construction that the GUID/fingerprint of certain `DepNode`s is a +/// valid `DefPathHash`. Since we also always build a huge table that maps every +/// `DefPathHash` in the current codebase to the corresponding `DefId`, we have +/// everything we need to re-run the query. +/// +/// Take the `mir_promoted` query as an example. Like many other queries, it +/// just has a single parameter: the `DefId` of the item it will compute the +/// validated MIR for. Now, when we call `force_from_dep_node()` on a `DepNode` +/// with kind `MirValidated`, we know that the GUID/fingerprint of the `DepNode` +/// is actually a `DefPathHash`, and can therefore just look up the corresponding +/// `DefId` in `tcx.def_path_hash_to_def_id`. +/// +/// When you implement a new query, it will likely have a corresponding new +/// `DepKind`, and you'll have to support it here in `force_from_dep_node()`. As +/// a rule of thumb, if your query takes a `DefId` or `LocalDefId` as sole parameter, +/// then `force_from_dep_node()` should not fail for it. Otherwise, you can just +/// add it to the "We don't have enough information to reconstruct..." group in +/// the match below. +pub fn force_from_dep_node<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> bool { + // We must avoid ever having to call `force_from_dep_node()` for a + // `DepNode::codegen_unit`: + // Since we cannot reconstruct the query key of a `DepNode::codegen_unit`, we + // would always end up having to evaluate the first caller of the + // `codegen_unit` query that *is* reconstructible. This might very well be + // the `compile_codegen_unit` query, thus re-codegenning the whole CGU just + // to re-trigger calling the `codegen_unit` query with the right key. At + // that point we would already have re-done all the work we are trying to + // avoid doing in the first place. + // The solution is simple: Just explicitly call the `codegen_unit` query for + // each CGU, right after partitioning. This way `try_mark_green` will always + // hit the cache instead of having to go through `force_from_dep_node`. + // This assertion makes sure, we actually keep applying the solution above. + debug_assert!( + dep_node.kind != DepKind::codegen_unit, + "calling force_from_dep_node() on DepKind::codegen_unit" + ); + + if !dep_node.kind.can_reconstruct_query_key() { + return false; + } + + rustc_dep_node_force!([dep_node, tcx] + // These are inputs that are expected to be pre-allocated and that + // should therefore always be red or green already. + DepKind::CrateMetadata | + + // These are anonymous nodes. + DepKind::TraitSelect | + + // We don't have enough information to reconstruct the query key of + // these. + DepKind::CompileCodegenUnit => { + bug!("force_from_dep_node: encountered {:?}", dep_node) + } + ); + + false +} + +pub(crate) fn try_load_from_on_disk_cache<'tcx>(tcx: TyCtxt<'tcx>, dep_node: &DepNode) { + rustc_dep_node_try_load_from_on_disk_cache!(dep_node, tcx) +} + +mod sealed { + use super::{DefId, LocalDefId}; + + /// An analogue of the `Into` trait that's intended only for query paramaters. + /// + /// This exists to allow queries to accept either `DefId` or `LocalDefId` while requiring that the + /// user call `to_def_id` to convert between them everywhere else. + pub trait IntoQueryParam<P> { + fn into_query_param(self) -> P; + } + + impl<P> IntoQueryParam<P> for P { + #[inline(always)] + fn into_query_param(self) -> P { + self + } + } + + impl IntoQueryParam<DefId> for LocalDefId { + #[inline(always)] + fn into_query_param(self) -> DefId { + self.to_def_id() + } + } +} + +use sealed::IntoQueryParam; diff --git a/compiler/rustc_middle/src/ty/query/on_disk_cache.rs b/compiler/rustc_middle/src/ty/query/on_disk_cache.rs new file mode 100644 index 00000000000..dcfb8d31430 --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/on_disk_cache.rs @@ -0,0 +1,1041 @@ +use crate::dep_graph::{DepNodeIndex, SerializedDepNodeIndex}; +use crate::mir::interpret::{AllocDecodingSession, AllocDecodingState}; +use crate::mir::{self, interpret}; +use crate::ty::codec::{OpaqueEncoder, RefDecodable, TyDecoder, TyEncoder}; +use crate::ty::context::TyCtxt; +use crate::ty::{self, Ty}; +use rustc_data_structures::fingerprint::{Fingerprint, FingerprintDecoder, FingerprintEncoder}; +use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet}; +use rustc_data_structures::sync::{HashMapExt, Lock, Lrc, OnceCell}; +use rustc_data_structures::thin_vec::ThinVec; +use rustc_errors::Diagnostic; +use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LocalDefId, LOCAL_CRATE}; +use rustc_hir::definitions::DefPathHash; +use rustc_index::vec::{Idx, IndexVec}; +use rustc_serialize::{opaque, Decodable, Decoder, Encodable, Encoder}; +use rustc_session::{CrateDisambiguator, Session}; +use rustc_span::hygiene::{ + ExpnDataDecodeMode, ExpnDataEncodeMode, ExpnId, HygieneDecodeContext, HygieneEncodeContext, + SyntaxContext, SyntaxContextData, +}; +use rustc_span::source_map::{SourceMap, StableSourceFileId}; +use rustc_span::CachingSourceMapView; +use rustc_span::{BytePos, ExpnData, SourceFile, Span, DUMMY_SP}; +use std::mem; + +const TAG_FILE_FOOTER: u128 = 0xC0FFEE_C0FFEE_C0FFEE_C0FFEE_C0FFEE; + +const TAG_VALID_SPAN: u8 = 0; +const TAG_INVALID_SPAN: u8 = 1; + +const TAG_SYNTAX_CONTEXT: u8 = 0; +const TAG_EXPN_DATA: u8 = 1; + +/// Provides an interface to incremental compilation data cached from the +/// previous compilation session. This data will eventually include the results +/// of a few selected queries (like `typeck` and `mir_optimized`) and +/// any diagnostics that have been emitted during a query. +pub struct OnDiskCache<'sess> { + // The complete cache data in serialized form. + serialized_data: Vec<u8>, + + // Collects all `Diagnostic`s emitted during the current compilation + // session. + current_diagnostics: Lock<FxHashMap<DepNodeIndex, Vec<Diagnostic>>>, + + prev_cnums: Vec<(u32, String, CrateDisambiguator)>, + cnum_map: OnceCell<IndexVec<CrateNum, Option<CrateNum>>>, + + source_map: &'sess SourceMap, + file_index_to_stable_id: FxHashMap<SourceFileIndex, StableSourceFileId>, + + // Caches that are populated lazily during decoding. + file_index_to_file: Lock<FxHashMap<SourceFileIndex, Lrc<SourceFile>>>, + + // A map from dep-node to the position of the cached query result in + // `serialized_data`. + query_result_index: FxHashMap<SerializedDepNodeIndex, AbsoluteBytePos>, + + // A map from dep-node to the position of any associated diagnostics in + // `serialized_data`. + prev_diagnostics_index: FxHashMap<SerializedDepNodeIndex, AbsoluteBytePos>, + + alloc_decoding_state: AllocDecodingState, + + // A map from syntax context ids to the position of their associated + // `SyntaxContextData`. We use a `u32` instead of a `SyntaxContext` + // to represent the fact that we are storing *encoded* ids. When we decode + // a `SyntaxContext`, a new id will be allocated from the global `HygieneData`, + // which will almost certainly be different than the serialized id. + syntax_contexts: FxHashMap<u32, AbsoluteBytePos>, + // A map from the `DefPathHash` of an `ExpnId` to the position + // of their associated `ExpnData`. Ideally, we would store a `DefId`, + // but we need to decode this before we've constructed a `TyCtxt` (which + // makes it difficult to decode a `DefId`). + + // Note that these `DefPathHashes` correspond to both local and foreign + // `ExpnData` (e.g `ExpnData.krate` may not be `LOCAL_CRATE`). Alternatively, + // we could look up the `ExpnData` from the metadata of foreign crates, + // but it seemed easier to have `OnDiskCache` be independent of the `CStore`. + expn_data: FxHashMap<u32, AbsoluteBytePos>, + // Additional information used when decoding hygiene data. + hygiene_context: HygieneDecodeContext, +} + +// This type is used only for serialization and deserialization. +#[derive(Encodable, Decodable)] +struct Footer { + file_index_to_stable_id: FxHashMap<SourceFileIndex, StableSourceFileId>, + prev_cnums: Vec<(u32, String, CrateDisambiguator)>, + query_result_index: EncodedQueryResultIndex, + diagnostics_index: EncodedQueryResultIndex, + // The location of all allocations. + interpret_alloc_index: Vec<u32>, + // See `OnDiskCache.syntax_contexts` + syntax_contexts: FxHashMap<u32, AbsoluteBytePos>, + // See `OnDiskCache.expn_data` + expn_data: FxHashMap<u32, AbsoluteBytePos>, +} + +type EncodedQueryResultIndex = Vec<(SerializedDepNodeIndex, AbsoluteBytePos)>; +type EncodedDiagnosticsIndex = Vec<(SerializedDepNodeIndex, AbsoluteBytePos)>; +type EncodedDiagnostics = Vec<Diagnostic>; + +#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, Encodable, Decodable)] +struct SourceFileIndex(u32); + +#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, Encodable, Decodable)] +struct AbsoluteBytePos(u32); + +impl AbsoluteBytePos { + fn new(pos: usize) -> AbsoluteBytePos { + debug_assert!(pos <= u32::MAX as usize); + AbsoluteBytePos(pos as u32) + } + + fn to_usize(self) -> usize { + self.0 as usize + } +} + +impl<'sess> OnDiskCache<'sess> { + /// Creates a new `OnDiskCache` instance from the serialized data in `data`. + pub fn new(sess: &'sess Session, data: Vec<u8>, start_pos: usize) -> Self { + debug_assert!(sess.opts.incremental.is_some()); + + // Wrap in a scope so we can borrow `data`. + let footer: Footer = { + let mut decoder = opaque::Decoder::new(&data[..], start_pos); + + // Decode the *position* of the footer, which can be found in the + // last 8 bytes of the file. + decoder.set_position(data.len() - IntEncodedWithFixedSize::ENCODED_SIZE); + let footer_pos = IntEncodedWithFixedSize::decode(&mut decoder) + .expect("error while trying to decode footer position") + .0 as usize; + + // Decode the file footer, which contains all the lookup tables, etc. + decoder.set_position(footer_pos); + + decode_tagged(&mut decoder, TAG_FILE_FOOTER) + .expect("error while trying to decode footer position") + }; + + Self { + serialized_data: data, + file_index_to_stable_id: footer.file_index_to_stable_id, + file_index_to_file: Default::default(), + prev_cnums: footer.prev_cnums, + cnum_map: OnceCell::new(), + source_map: sess.source_map(), + current_diagnostics: Default::default(), + query_result_index: footer.query_result_index.into_iter().collect(), + prev_diagnostics_index: footer.diagnostics_index.into_iter().collect(), + alloc_decoding_state: AllocDecodingState::new(footer.interpret_alloc_index), + syntax_contexts: footer.syntax_contexts, + expn_data: footer.expn_data, + hygiene_context: Default::default(), + } + } + + pub fn new_empty(source_map: &'sess SourceMap) -> Self { + Self { + serialized_data: Vec::new(), + file_index_to_stable_id: Default::default(), + file_index_to_file: Default::default(), + prev_cnums: vec![], + cnum_map: OnceCell::new(), + source_map, + current_diagnostics: Default::default(), + query_result_index: Default::default(), + prev_diagnostics_index: Default::default(), + alloc_decoding_state: AllocDecodingState::new(Vec::new()), + syntax_contexts: FxHashMap::default(), + expn_data: FxHashMap::default(), + hygiene_context: Default::default(), + } + } + + pub fn serialize<'tcx, E>(&self, tcx: TyCtxt<'tcx>, encoder: &mut E) -> Result<(), E::Error> + where + E: OpaqueEncoder, + { + // Serializing the `DepGraph` should not modify it. + tcx.dep_graph.with_ignore(|| { + // Allocate `SourceFileIndex`es. + let (file_to_file_index, file_index_to_stable_id) = { + let files = tcx.sess.source_map().files(); + let mut file_to_file_index = + FxHashMap::with_capacity_and_hasher(files.len(), Default::default()); + let mut file_index_to_stable_id = + FxHashMap::with_capacity_and_hasher(files.len(), Default::default()); + + for (index, file) in files.iter().enumerate() { + let index = SourceFileIndex(index as u32); + let file_ptr: *const SourceFile = &**file as *const _; + file_to_file_index.insert(file_ptr, index); + file_index_to_stable_id.insert(index, StableSourceFileId::new(&file)); + } + + (file_to_file_index, file_index_to_stable_id) + }; + + let hygiene_encode_context = HygieneEncodeContext::default(); + + let mut encoder = CacheEncoder { + tcx, + encoder, + type_shorthands: Default::default(), + predicate_shorthands: Default::default(), + interpret_allocs: Default::default(), + source_map: CachingSourceMapView::new(tcx.sess.source_map()), + file_to_file_index, + hygiene_context: &hygiene_encode_context, + }; + + // Load everything into memory so we can write it out to the on-disk + // cache. The vast majority of cacheable query results should already + // be in memory, so this should be a cheap operation. + tcx.dep_graph.exec_cache_promotions(tcx); + + // Encode query results. + let mut query_result_index = EncodedQueryResultIndex::new(); + + tcx.sess.time("encode_query_results", || { + let enc = &mut encoder; + let qri = &mut query_result_index; + + macro_rules! encode_queries { + ($($query:ident,)*) => { + $( + encode_query_results::<ty::query::queries::$query<'_>, _>( + tcx, + enc, + qri + )?; + )* + } + } + + rustc_cached_queries!(encode_queries!); + + Ok(()) + })?; + + // Encode diagnostics. + let diagnostics_index: EncodedDiagnosticsIndex = self + .current_diagnostics + .borrow() + .iter() + .map(|(dep_node_index, diagnostics)| { + let pos = AbsoluteBytePos::new(encoder.position()); + // Let's make sure we get the expected type here. + let diagnostics: &EncodedDiagnostics = diagnostics; + let dep_node_index = SerializedDepNodeIndex::new(dep_node_index.index()); + encoder.encode_tagged(dep_node_index, diagnostics)?; + + Ok((dep_node_index, pos)) + }) + .collect::<Result<_, _>>()?; + + let interpret_alloc_index = { + let mut interpret_alloc_index = Vec::new(); + let mut n = 0; + loop { + let new_n = encoder.interpret_allocs.len(); + // If we have found new IDs, serialize those too. + if n == new_n { + // Otherwise, abort. + break; + } + interpret_alloc_index.reserve(new_n - n); + for idx in n..new_n { + let id = encoder.interpret_allocs[idx]; + let pos = encoder.position() as u32; + interpret_alloc_index.push(pos); + interpret::specialized_encode_alloc_id(&mut encoder, tcx, id)?; + } + n = new_n; + } + interpret_alloc_index + }; + + let sorted_cnums = sorted_cnums_including_local_crate(tcx); + let prev_cnums: Vec<_> = sorted_cnums + .iter() + .map(|&cnum| { + let crate_name = tcx.original_crate_name(cnum).to_string(); + let crate_disambiguator = tcx.crate_disambiguator(cnum); + (cnum.as_u32(), crate_name, crate_disambiguator) + }) + .collect(); + + let mut syntax_contexts = FxHashMap::default(); + let mut expn_ids = FxHashMap::default(); + + // Encode all hygiene data (`SyntaxContextData` and `ExpnData`) from the current + // session. + + hygiene_encode_context.encode( + &mut encoder, + |encoder, index, ctxt_data| { + let pos = AbsoluteBytePos::new(encoder.position()); + encoder.encode_tagged(TAG_SYNTAX_CONTEXT, ctxt_data)?; + syntax_contexts.insert(index, pos); + Ok(()) + }, + |encoder, index, expn_data| { + let pos = AbsoluteBytePos::new(encoder.position()); + encoder.encode_tagged(TAG_EXPN_DATA, expn_data)?; + expn_ids.insert(index, pos); + Ok(()) + }, + )?; + + // `Encode the file footer. + let footer_pos = encoder.position() as u64; + encoder.encode_tagged( + TAG_FILE_FOOTER, + &Footer { + file_index_to_stable_id, + prev_cnums, + query_result_index, + diagnostics_index, + interpret_alloc_index, + syntax_contexts, + expn_data: expn_ids, + }, + )?; + + // Encode the position of the footer as the last 8 bytes of the + // file so we know where to look for it. + IntEncodedWithFixedSize(footer_pos).encode(encoder.encoder.opaque())?; + + // DO NOT WRITE ANYTHING TO THE ENCODER AFTER THIS POINT! The address + // of the footer must be the last thing in the data stream. + + return Ok(()); + + fn sorted_cnums_including_local_crate(tcx: TyCtxt<'_>) -> Vec<CrateNum> { + let mut cnums = vec![LOCAL_CRATE]; + cnums.extend_from_slice(&tcx.crates()[..]); + cnums.sort_unstable(); + // Just to be sure... + cnums.dedup(); + cnums + } + }) + } + + /// Loads a diagnostic emitted during the previous compilation session. + pub fn load_diagnostics( + &self, + tcx: TyCtxt<'_>, + dep_node_index: SerializedDepNodeIndex, + ) -> Vec<Diagnostic> { + let diagnostics: Option<EncodedDiagnostics> = + self.load_indexed(tcx, dep_node_index, &self.prev_diagnostics_index, "diagnostics"); + + diagnostics.unwrap_or_default() + } + + /// Stores a diagnostic emitted during the current compilation session. + /// Anything stored like this will be available via `load_diagnostics` in + /// the next compilation session. + #[inline(never)] + #[cold] + pub fn store_diagnostics( + &self, + dep_node_index: DepNodeIndex, + diagnostics: ThinVec<Diagnostic>, + ) { + let mut current_diagnostics = self.current_diagnostics.borrow_mut(); + let prev = current_diagnostics.insert(dep_node_index, diagnostics.into()); + debug_assert!(prev.is_none()); + } + + /// Returns the cached query result if there is something in the cache for + /// the given `SerializedDepNodeIndex`; otherwise returns `None`. + crate fn try_load_query_result<'tcx, T>( + &self, + tcx: TyCtxt<'tcx>, + dep_node_index: SerializedDepNodeIndex, + ) -> Option<T> + where + T: for<'a> Decodable<CacheDecoder<'a, 'tcx>>, + { + self.load_indexed(tcx, dep_node_index, &self.query_result_index, "query result") + } + + /// Stores a diagnostic emitted during computation of an anonymous query. + /// Since many anonymous queries can share the same `DepNode`, we aggregate + /// them -- as opposed to regular queries where we assume that there is a + /// 1:1 relationship between query-key and `DepNode`. + #[inline(never)] + #[cold] + pub fn store_diagnostics_for_anon_node( + &self, + dep_node_index: DepNodeIndex, + diagnostics: ThinVec<Diagnostic>, + ) { + let mut current_diagnostics = self.current_diagnostics.borrow_mut(); + + let x = current_diagnostics.entry(dep_node_index).or_insert(Vec::new()); + + x.extend(Into::<Vec<_>>::into(diagnostics)); + } + + fn load_indexed<'tcx, T>( + &self, + tcx: TyCtxt<'tcx>, + dep_node_index: SerializedDepNodeIndex, + index: &FxHashMap<SerializedDepNodeIndex, AbsoluteBytePos>, + debug_tag: &'static str, + ) -> Option<T> + where + T: for<'a> Decodable<CacheDecoder<'a, 'tcx>>, + { + let pos = index.get(&dep_node_index).cloned()?; + + self.with_decoder(tcx, pos, |decoder| match decode_tagged(decoder, dep_node_index) { + Ok(v) => Some(v), + Err(e) => bug!("could not decode cached {}: {}", debug_tag, e), + }) + } + + fn with_decoder<'a, 'tcx, T, F: FnOnce(&mut CacheDecoder<'sess, 'tcx>) -> T>( + &'sess self, + tcx: TyCtxt<'tcx>, + pos: AbsoluteBytePos, + f: F, + ) -> T + where + T: Decodable<CacheDecoder<'a, 'tcx>>, + { + let cnum_map = + self.cnum_map.get_or_init(|| Self::compute_cnum_map(tcx, &self.prev_cnums[..])); + + let mut decoder = CacheDecoder { + tcx, + opaque: opaque::Decoder::new(&self.serialized_data[..], pos.to_usize()), + source_map: self.source_map, + cnum_map, + file_index_to_file: &self.file_index_to_file, + file_index_to_stable_id: &self.file_index_to_stable_id, + alloc_decoding_session: self.alloc_decoding_state.new_decoding_session(), + syntax_contexts: &self.syntax_contexts, + expn_data: &self.expn_data, + hygiene_context: &self.hygiene_context, + }; + f(&mut decoder) + } + + // This function builds mapping from previous-session-`CrateNum` to + // current-session-`CrateNum`. There might be `CrateNum`s from the previous + // `Session` that don't occur in the current one. For these, the mapping + // maps to None. + fn compute_cnum_map( + tcx: TyCtxt<'_>, + prev_cnums: &[(u32, String, CrateDisambiguator)], + ) -> IndexVec<CrateNum, Option<CrateNum>> { + tcx.dep_graph.with_ignore(|| { + let current_cnums = tcx + .all_crate_nums(LOCAL_CRATE) + .iter() + .map(|&cnum| { + let crate_name = tcx.original_crate_name(cnum).to_string(); + let crate_disambiguator = tcx.crate_disambiguator(cnum); + ((crate_name, crate_disambiguator), cnum) + }) + .collect::<FxHashMap<_, _>>(); + + let map_size = prev_cnums.iter().map(|&(cnum, ..)| cnum).max().unwrap_or(0) + 1; + let mut map = IndexVec::from_elem_n(None, map_size as usize); + + for &(prev_cnum, ref crate_name, crate_disambiguator) in prev_cnums { + let key = (crate_name.clone(), crate_disambiguator); + map[CrateNum::from_u32(prev_cnum)] = current_cnums.get(&key).cloned(); + } + + map[LOCAL_CRATE] = Some(LOCAL_CRATE); + map + }) + } +} + +//- DECODING ------------------------------------------------------------------- + +/// A decoder that can read from the incr. comp. cache. It is similar to the one +/// we use for crate metadata decoding in that it can rebase spans and eventually +/// will also handle things that contain `Ty` instances. +crate struct CacheDecoder<'a, 'tcx> { + tcx: TyCtxt<'tcx>, + opaque: opaque::Decoder<'a>, + source_map: &'a SourceMap, + cnum_map: &'a IndexVec<CrateNum, Option<CrateNum>>, + file_index_to_file: &'a Lock<FxHashMap<SourceFileIndex, Lrc<SourceFile>>>, + file_index_to_stable_id: &'a FxHashMap<SourceFileIndex, StableSourceFileId>, + alloc_decoding_session: AllocDecodingSession<'a>, + syntax_contexts: &'a FxHashMap<u32, AbsoluteBytePos>, + expn_data: &'a FxHashMap<u32, AbsoluteBytePos>, + hygiene_context: &'a HygieneDecodeContext, +} + +impl<'a, 'tcx> CacheDecoder<'a, 'tcx> { + fn file_index_to_file(&self, index: SourceFileIndex) -> Lrc<SourceFile> { + let CacheDecoder { + ref file_index_to_file, + ref file_index_to_stable_id, + ref source_map, + .. + } = *self; + + file_index_to_file + .borrow_mut() + .entry(index) + .or_insert_with(|| { + let stable_id = file_index_to_stable_id[&index]; + source_map + .source_file_by_stable_id(stable_id) + .expect("failed to lookup `SourceFile` in new context") + }) + .clone() + } +} + +trait DecoderWithPosition: Decoder { + fn position(&self) -> usize; +} + +impl<'a> DecoderWithPosition for opaque::Decoder<'a> { + fn position(&self) -> usize { + self.position() + } +} + +impl<'a, 'tcx> DecoderWithPosition for CacheDecoder<'a, 'tcx> { + fn position(&self) -> usize { + self.opaque.position() + } +} + +// Decodes something that was encoded with `encode_tagged()` and verify that the +// tag matches and the correct amount of bytes was read. +fn decode_tagged<D, T, V>(decoder: &mut D, expected_tag: T) -> Result<V, D::Error> +where + T: Decodable<D> + Eq + ::std::fmt::Debug, + V: Decodable<D>, + D: DecoderWithPosition, +{ + let start_pos = decoder.position(); + + let actual_tag = T::decode(decoder)?; + assert_eq!(actual_tag, expected_tag); + let value = V::decode(decoder)?; + let end_pos = decoder.position(); + + let expected_len: u64 = Decodable::decode(decoder)?; + assert_eq!((end_pos - start_pos) as u64, expected_len); + + Ok(value) +} + +impl<'a, 'tcx> TyDecoder<'tcx> for CacheDecoder<'a, 'tcx> { + const CLEAR_CROSS_CRATE: bool = false; + + #[inline] + fn tcx(&self) -> TyCtxt<'tcx> { + self.tcx + } + + #[inline] + fn position(&self) -> usize { + self.opaque.position() + } + + #[inline] + fn peek_byte(&self) -> u8 { + self.opaque.data[self.opaque.position()] + } + + fn cached_ty_for_shorthand<F>( + &mut self, + shorthand: usize, + or_insert_with: F, + ) -> Result<Ty<'tcx>, Self::Error> + where + F: FnOnce(&mut Self) -> Result<Ty<'tcx>, Self::Error>, + { + let tcx = self.tcx(); + + let cache_key = + ty::CReaderCacheKey { cnum: CrateNum::ReservedForIncrCompCache, pos: shorthand }; + + if let Some(&ty) = tcx.ty_rcache.borrow().get(&cache_key) { + return Ok(ty); + } + + let ty = or_insert_with(self)?; + // This may overwrite the entry, but it should overwrite with the same value. + tcx.ty_rcache.borrow_mut().insert_same(cache_key, ty); + Ok(ty) + } + + fn cached_predicate_for_shorthand<F>( + &mut self, + shorthand: usize, + or_insert_with: F, + ) -> Result<ty::Predicate<'tcx>, Self::Error> + where + F: FnOnce(&mut Self) -> Result<ty::Predicate<'tcx>, Self::Error>, + { + let tcx = self.tcx(); + + let cache_key = + ty::CReaderCacheKey { cnum: CrateNum::ReservedForIncrCompCache, pos: shorthand }; + + if let Some(&pred) = tcx.pred_rcache.borrow().get(&cache_key) { + return Ok(pred); + } + + let pred = or_insert_with(self)?; + // This may overwrite the entry, but it should overwrite with the same value. + tcx.pred_rcache.borrow_mut().insert_same(cache_key, pred); + Ok(pred) + } + + fn with_position<F, R>(&mut self, pos: usize, f: F) -> R + where + F: FnOnce(&mut Self) -> R, + { + debug_assert!(pos < self.opaque.data.len()); + + let new_opaque = opaque::Decoder::new(self.opaque.data, pos); + let old_opaque = mem::replace(&mut self.opaque, new_opaque); + let r = f(self); + self.opaque = old_opaque; + r + } + + fn map_encoded_cnum_to_current(&self, cnum: CrateNum) -> CrateNum { + self.cnum_map[cnum].unwrap_or_else(|| bug!("could not find new `CrateNum` for {:?}", cnum)) + } + + fn decode_alloc_id(&mut self) -> Result<interpret::AllocId, Self::Error> { + let alloc_decoding_session = self.alloc_decoding_session; + alloc_decoding_session.decode_alloc_id(self) + } +} + +crate::implement_ty_decoder!(CacheDecoder<'a, 'tcx>); + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for SyntaxContext { + fn decode(decoder: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + let syntax_contexts = decoder.syntax_contexts; + rustc_span::hygiene::decode_syntax_context(decoder, decoder.hygiene_context, |this, id| { + // This closure is invoked if we haven't already decoded the data for the `SyntaxContext` we are deserializing. + // We look up the position of the associated `SyntaxData` and decode it. + let pos = syntax_contexts.get(&id).unwrap(); + this.with_position(pos.to_usize(), |decoder| { + let data: SyntaxContextData = decode_tagged(decoder, TAG_SYNTAX_CONTEXT)?; + Ok(data) + }) + }) + } +} + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for ExpnId { + fn decode(decoder: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + let expn_data = decoder.expn_data; + rustc_span::hygiene::decode_expn_id( + decoder, + ExpnDataDecodeMode::incr_comp(decoder.hygiene_context), + |this, index| { + // This closure is invoked if we haven't already decoded the data for the `ExpnId` we are deserializing. + // We look up the position of the associated `ExpnData` and decode it. + let pos = expn_data + .get(&index) + .unwrap_or_else(|| panic!("Bad index {:?} (map {:?})", index, expn_data)); + + this.with_position(pos.to_usize(), |decoder| { + let data: ExpnData = decode_tagged(decoder, TAG_EXPN_DATA)?; + Ok(data) + }) + }, + ) + } +} + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for Span { + fn decode(decoder: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + let tag: u8 = Decodable::decode(decoder)?; + + if tag == TAG_INVALID_SPAN { + return Ok(DUMMY_SP); + } else { + debug_assert_eq!(tag, TAG_VALID_SPAN); + } + + let file_lo_index = SourceFileIndex::decode(decoder)?; + let line_lo = usize::decode(decoder)?; + let col_lo = BytePos::decode(decoder)?; + let len = BytePos::decode(decoder)?; + let ctxt = SyntaxContext::decode(decoder)?; + + let file_lo = decoder.file_index_to_file(file_lo_index); + let lo = file_lo.lines[line_lo - 1] + col_lo; + let hi = lo + len; + + Ok(Span::new(lo, hi, ctxt)) + } +} + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for CrateNum { + fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + let cnum = CrateNum::from_u32(u32::decode(d)?); + Ok(d.map_encoded_cnum_to_current(cnum)) + } +} + +// This impl makes sure that we get a runtime error when we try decode a +// `DefIndex` that is not contained in a `DefId`. Such a case would be problematic +// because we would not know how to transform the `DefIndex` to the current +// context. +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for DefIndex { + fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<DefIndex, String> { + Err(d.error("trying to decode `DefIndex` outside the context of a `DefId`")) + } +} + +// Both the `CrateNum` and the `DefIndex` of a `DefId` can change in between two +// compilation sessions. We use the `DefPathHash`, which is stable across +// sessions, to map the old `DefId` to the new one. +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for DefId { + fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + // Load the `DefPathHash` which is was we encoded the `DefId` as. + let def_path_hash = DefPathHash::decode(d)?; + + // Using the `DefPathHash`, we can lookup the new `DefId`. + Ok(d.tcx().def_path_hash_to_def_id.as_ref().unwrap()[&def_path_hash]) + } +} + +impl<'a, 'tcx> FingerprintDecoder for CacheDecoder<'a, 'tcx> { + fn decode_fingerprint(&mut self) -> Result<Fingerprint, Self::Error> { + Fingerprint::decode_opaque(&mut self.opaque) + } +} + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx FxHashSet<LocalDefId> { + fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + RefDecodable::decode(d) + } +} + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> + for &'tcx IndexVec<mir::Promoted, mir::Body<'tcx>> +{ + fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + RefDecodable::decode(d) + } +} + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [(ty::Predicate<'tcx>, Span)] { + fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + RefDecodable::decode(d) + } +} + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [rustc_ast::InlineAsmTemplatePiece] { + fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + RefDecodable::decode(d) + } +} + +impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [Span] { + fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Result<Self, String> { + RefDecodable::decode(d) + } +} + +//- ENCODING ------------------------------------------------------------------- + +/// An encoder that can write the incr. comp. cache. +struct CacheEncoder<'a, 'tcx, E: OpaqueEncoder> { + tcx: TyCtxt<'tcx>, + encoder: &'a mut E, + type_shorthands: FxHashMap<Ty<'tcx>, usize>, + predicate_shorthands: FxHashMap<ty::Predicate<'tcx>, usize>, + interpret_allocs: FxIndexSet<interpret::AllocId>, + source_map: CachingSourceMapView<'tcx>, + file_to_file_index: FxHashMap<*const SourceFile, SourceFileIndex>, + hygiene_context: &'a HygieneEncodeContext, +} + +impl<'a, 'tcx, E> CacheEncoder<'a, 'tcx, E> +where + E: 'a + OpaqueEncoder, +{ + fn source_file_index(&mut self, source_file: Lrc<SourceFile>) -> SourceFileIndex { + self.file_to_file_index[&(&*source_file as *const SourceFile)] + } + + /// Encode something with additional information that allows to do some + /// sanity checks when decoding the data again. This method will first + /// encode the specified tag, then the given value, then the number of + /// bytes taken up by tag and value. On decoding, we can then verify that + /// we get the expected tag and read the expected number of bytes. + fn encode_tagged<T: Encodable<Self>, V: Encodable<Self>>( + &mut self, + tag: T, + value: &V, + ) -> Result<(), E::Error> { + let start_pos = self.position(); + + tag.encode(self)?; + value.encode(self)?; + + let end_pos = self.position(); + ((end_pos - start_pos) as u64).encode(self) + } +} + +impl<'a, 'tcx> FingerprintEncoder for CacheEncoder<'a, 'tcx, rustc_serialize::opaque::Encoder> { + fn encode_fingerprint(&mut self, f: &Fingerprint) -> opaque::EncodeResult { + f.encode_opaque(self.encoder) + } +} + +impl<'a, 'tcx, E> Encodable<CacheEncoder<'a, 'tcx, E>> for SyntaxContext +where + E: 'a + OpaqueEncoder, +{ + fn encode(&self, s: &mut CacheEncoder<'a, 'tcx, E>) -> Result<(), E::Error> { + rustc_span::hygiene::raw_encode_syntax_context(*self, s.hygiene_context, s) + } +} + +impl<'a, 'tcx, E> Encodable<CacheEncoder<'a, 'tcx, E>> for ExpnId +where + E: 'a + OpaqueEncoder, +{ + fn encode(&self, s: &mut CacheEncoder<'a, 'tcx, E>) -> Result<(), E::Error> { + rustc_span::hygiene::raw_encode_expn_id( + *self, + s.hygiene_context, + ExpnDataEncodeMode::IncrComp, + s, + ) + } +} + +impl<'a, 'tcx, E> Encodable<CacheEncoder<'a, 'tcx, E>> for Span +where + E: 'a + OpaqueEncoder, +{ + fn encode(&self, s: &mut CacheEncoder<'a, 'tcx, E>) -> Result<(), E::Error> { + if *self == DUMMY_SP { + return TAG_INVALID_SPAN.encode(s); + } + + let span_data = self.data(); + let (file_lo, line_lo, col_lo) = match s.source_map.byte_pos_to_line_and_col(span_data.lo) { + Some(pos) => pos, + None => return TAG_INVALID_SPAN.encode(s), + }; + + if !file_lo.contains(span_data.hi) { + return TAG_INVALID_SPAN.encode(s); + } + + let len = span_data.hi - span_data.lo; + + let source_file_index = s.source_file_index(file_lo); + + TAG_VALID_SPAN.encode(s)?; + source_file_index.encode(s)?; + line_lo.encode(s)?; + col_lo.encode(s)?; + len.encode(s)?; + span_data.ctxt.encode(s) + } +} + +impl<'a, 'tcx, E> TyEncoder<'tcx> for CacheEncoder<'a, 'tcx, E> +where + E: 'a + OpaqueEncoder, +{ + const CLEAR_CROSS_CRATE: bool = false; + + fn tcx(&self) -> TyCtxt<'tcx> { + self.tcx + } + fn position(&self) -> usize { + self.encoder.encoder_position() + } + fn type_shorthands(&mut self) -> &mut FxHashMap<Ty<'tcx>, usize> { + &mut self.type_shorthands + } + fn predicate_shorthands(&mut self) -> &mut FxHashMap<ty::Predicate<'tcx>, usize> { + &mut self.predicate_shorthands + } + fn encode_alloc_id(&mut self, alloc_id: &interpret::AllocId) -> Result<(), Self::Error> { + let (index, _) = self.interpret_allocs.insert_full(*alloc_id); + + index.encode(self) + } +} + +impl<'a, 'tcx, E> Encodable<CacheEncoder<'a, 'tcx, E>> for DefId +where + E: 'a + OpaqueEncoder, +{ + fn encode(&self, s: &mut CacheEncoder<'a, 'tcx, E>) -> Result<(), E::Error> { + let def_path_hash = s.tcx.def_path_hash(*self); + def_path_hash.encode(s) + } +} + +impl<'a, 'tcx, E> Encodable<CacheEncoder<'a, 'tcx, E>> for DefIndex +where + E: 'a + OpaqueEncoder, +{ + fn encode(&self, _: &mut CacheEncoder<'a, 'tcx, E>) -> Result<(), E::Error> { + bug!("encoding `DefIndex` without context"); + } +} + +macro_rules! encoder_methods { + ($($name:ident($ty:ty);)*) => { + #[inline] + $(fn $name(&mut self, value: $ty) -> Result<(), Self::Error> { + self.encoder.$name(value) + })* + } +} + +impl<'a, 'tcx, E> Encoder for CacheEncoder<'a, 'tcx, E> +where + E: 'a + OpaqueEncoder, +{ + type Error = E::Error; + + #[inline] + fn emit_unit(&mut self) -> Result<(), Self::Error> { + Ok(()) + } + + encoder_methods! { + emit_usize(usize); + emit_u128(u128); + emit_u64(u64); + emit_u32(u32); + emit_u16(u16); + emit_u8(u8); + + emit_isize(isize); + emit_i128(i128); + emit_i64(i64); + emit_i32(i32); + emit_i16(i16); + emit_i8(i8); + + emit_bool(bool); + emit_f64(f64); + emit_f32(f32); + emit_char(char); + emit_str(&str); + } +} + +// An integer that will always encode to 8 bytes. +struct IntEncodedWithFixedSize(u64); + +impl IntEncodedWithFixedSize { + pub const ENCODED_SIZE: usize = 8; +} + +impl Encodable<opaque::Encoder> for IntEncodedWithFixedSize { + fn encode(&self, e: &mut opaque::Encoder) -> Result<(), !> { + let start_pos = e.position(); + for i in 0..IntEncodedWithFixedSize::ENCODED_SIZE { + ((self.0 >> (i * 8)) as u8).encode(e)?; + } + let end_pos = e.position(); + assert_eq!((end_pos - start_pos), IntEncodedWithFixedSize::ENCODED_SIZE); + Ok(()) + } +} + +impl<'a> Decodable<opaque::Decoder<'a>> for IntEncodedWithFixedSize { + fn decode(decoder: &mut opaque::Decoder<'a>) -> Result<IntEncodedWithFixedSize, String> { + let mut value: u64 = 0; + let start_pos = decoder.position(); + + for i in 0..IntEncodedWithFixedSize::ENCODED_SIZE { + let byte: u8 = Decodable::decode(decoder)?; + value |= (byte as u64) << (i * 8); + } + + let end_pos = decoder.position(); + assert_eq!((end_pos - start_pos), IntEncodedWithFixedSize::ENCODED_SIZE); + + Ok(IntEncodedWithFixedSize(value)) + } +} + +fn encode_query_results<'a, 'tcx, Q, E>( + tcx: TyCtxt<'tcx>, + encoder: &mut CacheEncoder<'a, 'tcx, E>, + query_result_index: &mut EncodedQueryResultIndex, +) -> Result<(), E::Error> +where + Q: super::QueryDescription<TyCtxt<'tcx>> + super::QueryAccessors<TyCtxt<'tcx>>, + Q::Value: Encodable<CacheEncoder<'a, 'tcx, E>>, + E: 'a + OpaqueEncoder, +{ + let _timer = tcx + .sess + .prof + .extra_verbose_generic_activity("encode_query_results_for", ::std::any::type_name::<Q>()); + + let state = Q::query_state(tcx); + assert!(state.all_inactive()); + + state.iter_results(|results| { + for (key, value, dep_node) in results { + if Q::cache_on_disk(tcx, &key, Some(value)) { + let dep_node = SerializedDepNodeIndex::new(dep_node.index()); + + // Record position of the cache entry. + query_result_index + .push((dep_node, AbsoluteBytePos::new(encoder.encoder.opaque().position()))); + + // Encode the type check tables with the `SerializedDepNodeIndex` + // as tag. + encoder.encode_tagged(dep_node, value)?; + } + } + Ok(()) + }) +} diff --git a/compiler/rustc_middle/src/ty/query/plumbing.rs b/compiler/rustc_middle/src/ty/query/plumbing.rs new file mode 100644 index 00000000000..f3fa3634026 --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/plumbing.rs @@ -0,0 +1,578 @@ +//! The implementation of the query system itself. This defines the macros that +//! generate the actual methods on tcx which find and execute the provider, +//! manage the caches, and so forth. + +use crate::dep_graph::DepGraph; +use crate::ty::query::Query; +use crate::ty::tls::{self, ImplicitCtxt}; +use crate::ty::{self, TyCtxt}; +use rustc_query_system::query::QueryContext; +use rustc_query_system::query::{CycleError, QueryJobId, QueryJobInfo}; + +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::sync::Lock; +use rustc_data_structures::thin_vec::ThinVec; +use rustc_errors::{struct_span_err, Diagnostic, DiagnosticBuilder, Handler, Level}; +use rustc_span::def_id::DefId; +use rustc_span::Span; + +impl QueryContext for TyCtxt<'tcx> { + type Query = Query<'tcx>; + + fn incremental_verify_ich(&self) -> bool { + self.sess.opts.debugging_opts.incremental_verify_ich + } + fn verbose(&self) -> bool { + self.sess.verbose() + } + + fn def_path_str(&self, def_id: DefId) -> String { + TyCtxt::def_path_str(*self, def_id) + } + + fn dep_graph(&self) -> &DepGraph { + &self.dep_graph + } + + fn current_query_job(&self) -> Option<QueryJobId<Self::DepKind>> { + tls::with_related_context(*self, |icx| icx.query) + } + + fn try_collect_active_jobs( + &self, + ) -> Option<FxHashMap<QueryJobId<Self::DepKind>, QueryJobInfo<Self>>> { + self.queries.try_collect_active_jobs() + } + + /// Executes a job by changing the `ImplicitCtxt` to point to the + /// new query job while it executes. It returns the diagnostics + /// captured during execution and the actual result. + #[inline(always)] + fn start_query<R>( + &self, + token: QueryJobId<Self::DepKind>, + diagnostics: Option<&Lock<ThinVec<Diagnostic>>>, + compute: impl FnOnce(Self) -> R, + ) -> R { + // The `TyCtxt` stored in TLS has the same global interner lifetime + // as `self`, so we use `with_related_context` to relate the 'tcx lifetimes + // when accessing the `ImplicitCtxt`. + tls::with_related_context(*self, move |current_icx| { + // Update the `ImplicitCtxt` to point to our new query job. + let new_icx = ImplicitCtxt { + tcx: *self, + query: Some(token), + diagnostics, + layout_depth: current_icx.layout_depth, + task_deps: current_icx.task_deps, + }; + + // Use the `ImplicitCtxt` while we execute the query. + tls::enter_context(&new_icx, |_| { + rustc_data_structures::stack::ensure_sufficient_stack(|| compute(*self)) + }) + }) + } +} + +impl<'tcx> TyCtxt<'tcx> { + #[inline(never)] + #[cold] + pub(super) fn report_cycle( + self, + CycleError { usage, cycle: stack }: CycleError<Query<'tcx>>, + ) -> DiagnosticBuilder<'tcx> { + assert!(!stack.is_empty()); + + let fix_span = |span: Span, query: &Query<'tcx>| { + self.sess.source_map().guess_head_span(query.default_span(self, span)) + }; + + // Disable naming impls with types in this path, since that + // sometimes cycles itself, leading to extra cycle errors. + // (And cycle errors around impls tend to occur during the + // collect/coherence phases anyhow.) + ty::print::with_forced_impl_filename_line(|| { + let span = fix_span(stack[1 % stack.len()].span, &stack[0].query); + let mut err = struct_span_err!( + self.sess, + span, + E0391, + "cycle detected when {}", + stack[0].query.describe(self) + ); + + for i in 1..stack.len() { + let query = &stack[i].query; + let span = fix_span(stack[(i + 1) % stack.len()].span, query); + err.span_note(span, &format!("...which requires {}...", query.describe(self))); + } + + err.note(&format!( + "...which again requires {}, completing the cycle", + stack[0].query.describe(self) + )); + + if let Some((span, query)) = usage { + err.span_note( + fix_span(span, &query), + &format!("cycle used when {}", query.describe(self)), + ); + } + + err + }) + } + + pub fn try_print_query_stack(handler: &Handler) { + eprintln!("query stack during panic:"); + + // Be careful reyling on global state here: this code is called from + // a panic hook, which means that the global `Handler` may be in a weird + // state if it was responsible for triggering the panic. + ty::tls::with_context_opt(|icx| { + if let Some(icx) = icx { + let query_map = icx.tcx.queries.try_collect_active_jobs(); + + let mut current_query = icx.query; + let mut i = 0; + + while let Some(query) = current_query { + let query_info = + if let Some(info) = query_map.as_ref().and_then(|map| map.get(&query)) { + info + } else { + break; + }; + let mut diag = Diagnostic::new( + Level::FailureNote, + &format!( + "#{} [{}] {}", + i, + query_info.info.query.name(), + query_info.info.query.describe(icx.tcx) + ), + ); + diag.span = + icx.tcx.sess.source_map().guess_head_span(query_info.info.span).into(); + handler.force_print_diagnostic(diag); + + current_query = query_info.job.parent; + i += 1; + } + } + }); + + eprintln!("end of query stack"); + } +} + +macro_rules! handle_cycle_error { + ([][$tcx: expr, $error:expr]) => {{ + $tcx.report_cycle($error).emit(); + Value::from_cycle_error($tcx) + }}; + ([fatal_cycle $($rest:tt)*][$tcx:expr, $error:expr]) => {{ + $tcx.report_cycle($error).emit(); + $tcx.sess.abort_if_errors(); + unreachable!() + }}; + ([cycle_delay_bug $($rest:tt)*][$tcx:expr, $error:expr]) => {{ + $tcx.report_cycle($error).delay_as_bug(); + Value::from_cycle_error($tcx) + }}; + ([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*][$($args:tt)*]) => { + handle_cycle_error!([$($($modifiers)*)*][$($args)*]) + }; +} + +macro_rules! is_anon { + ([]) => {{ + false + }}; + ([anon $($rest:tt)*]) => {{ + true + }}; + ([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*]) => { + is_anon!([$($($modifiers)*)*]) + }; +} + +macro_rules! is_eval_always { + ([]) => {{ + false + }}; + ([eval_always $($rest:tt)*]) => {{ + true + }}; + ([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*]) => { + is_eval_always!([$($($modifiers)*)*]) + }; +} + +macro_rules! query_storage { + ([][$K:ty, $V:ty]) => { + <<$K as Key>::CacheSelector as CacheSelector<$K, $V>>::Cache + }; + ([storage($ty:ty) $($rest:tt)*][$K:ty, $V:ty]) => { + <$ty as CacheSelector<$K, $V>>::Cache + }; + ([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*][$($args:tt)*]) => { + query_storage!([$($($modifiers)*)*][$($args)*]) + }; +} + +macro_rules! hash_result { + ([][$hcx:expr, $result:expr]) => {{ + dep_graph::hash_result($hcx, &$result) + }}; + ([no_hash $($rest:tt)*][$hcx:expr, $result:expr]) => {{ + None + }}; + ([$other:ident $(($($other_args:tt)*))* $(, $($modifiers:tt)*)*][$($args:tt)*]) => { + hash_result!([$($($modifiers)*)*][$($args)*]) + }; +} + +macro_rules! define_queries { + (<$tcx:tt> $($category:tt { + $($(#[$attr:meta])* [$($modifiers:tt)*] fn $name:ident: $node:ident($($K:tt)*) -> $V:ty,)* + },)*) => { + define_queries_inner! { <$tcx> + $($( $(#[$attr])* category<$category> [$($modifiers)*] fn $name: $node($($K)*) -> $V,)*)* + } + } +} + +macro_rules! query_helper_param_ty { + (DefId) => { impl IntoQueryParam<DefId> }; + ($K:ty) => { $K }; +} + +macro_rules! define_queries_inner { + (<$tcx:tt> + $($(#[$attr:meta])* category<$category:tt> + [$($modifiers:tt)*] fn $name:ident: $node:ident($($K:tt)*) -> $V:ty,)*) => { + + use std::mem; + use crate::{ + rustc_data_structures::stable_hasher::HashStable, + rustc_data_structures::stable_hasher::StableHasher, + ich::StableHashingContext + }; + use rustc_data_structures::profiling::ProfileCategory; + + define_queries_struct! { + tcx: $tcx, + input: ($(([$($modifiers)*] [$($attr)*] [$name]))*) + } + + #[allow(nonstandard_style)] + #[derive(Clone, Debug)] + pub enum Query<$tcx> { + $($(#[$attr])* $name($($K)*)),* + } + + impl<$tcx> Query<$tcx> { + pub fn name(&self) -> &'static str { + match *self { + $(Query::$name(_) => stringify!($name),)* + } + } + + pub fn describe(&self, tcx: TyCtxt<$tcx>) -> Cow<'static, str> { + let (r, name) = match *self { + $(Query::$name(key) => { + (queries::$name::describe(tcx, key), stringify!($name)) + })* + }; + if tcx.sess.verbose() { + format!("{} [{}]", r, name).into() + } else { + r + } + } + + // FIXME(eddyb) Get more valid `Span`s on queries. + pub fn default_span(&self, tcx: TyCtxt<$tcx>, span: Span) -> Span { + if !span.is_dummy() { + return span; + } + // The `def_span` query is used to calculate `default_span`, + // so exit to avoid infinite recursion. + if let Query::def_span(..) = *self { + return span + } + match *self { + $(Query::$name(key) => key.default_span(tcx),)* + } + } + } + + impl<'a, $tcx> HashStable<StableHashingContext<'a>> for Query<$tcx> { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + mem::discriminant(self).hash_stable(hcx, hasher); + match *self { + $(Query::$name(key) => key.hash_stable(hcx, hasher),)* + } + } + } + + #[allow(nonstandard_style)] + pub mod queries { + use std::marker::PhantomData; + + $(pub struct $name<$tcx> { + data: PhantomData<&$tcx ()> + })* + } + + // HACK(eddyb) this is like the `impl QueryConfig for queries::$name` + // below, but using type aliases instead of associated types, to bypass + // the limitations around normalizing under HRTB - for example, this: + // `for<'tcx> fn(...) -> <queries::$name<'tcx> as QueryConfig<TyCtxt<'tcx>>>::Value` + // doesn't currently normalize to `for<'tcx> fn(...) -> query_values::$name<'tcx>`. + // This is primarily used by the `provide!` macro in `rustc_metadata`. + #[allow(nonstandard_style, unused_lifetimes)] + pub mod query_keys { + use super::*; + + $(pub type $name<$tcx> = $($K)*;)* + } + #[allow(nonstandard_style, unused_lifetimes)] + pub mod query_values { + use super::*; + + $(pub type $name<$tcx> = $V;)* + } + + $(impl<$tcx> QueryConfig<TyCtxt<$tcx>> for queries::$name<$tcx> { + type Key = $($K)*; + type Value = $V; + type Stored = < + query_storage!([$($modifiers)*][$($K)*, $V]) + as QueryStorage + >::Stored; + const NAME: &'static str = stringify!($name); + const CATEGORY: ProfileCategory = $category; + } + + impl<$tcx> QueryAccessors<TyCtxt<$tcx>> for queries::$name<$tcx> { + const ANON: bool = is_anon!([$($modifiers)*]); + const EVAL_ALWAYS: bool = is_eval_always!([$($modifiers)*]); + const DEP_KIND: dep_graph::DepKind = dep_graph::DepKind::$node; + + type Cache = query_storage!([$($modifiers)*][$($K)*, $V]); + + #[inline(always)] + fn query_state<'a>(tcx: TyCtxt<$tcx>) -> &'a QueryState<TyCtxt<$tcx>, Self::Cache> { + &tcx.queries.$name + } + + #[inline] + fn compute(tcx: TyCtxt<'tcx>, key: Self::Key) -> Self::Value { + let provider = tcx.queries.providers.get(key.query_crate()) + // HACK(eddyb) it's possible crates may be loaded after + // the query engine is created, and because crate loading + // is not yet integrated with the query engine, such crates + // would be missing appropriate entries in `providers`. + .unwrap_or(&tcx.queries.fallback_extern_providers) + .$name; + provider(tcx, key) + } + + fn hash_result( + _hcx: &mut StableHashingContext<'_>, + _result: &Self::Value + ) -> Option<Fingerprint> { + hash_result!([$($modifiers)*][_hcx, _result]) + } + + fn handle_cycle_error( + tcx: TyCtxt<'tcx>, + error: CycleError<Query<'tcx>> + ) -> Self::Value { + handle_cycle_error!([$($modifiers)*][tcx, error]) + } + })* + + #[derive(Copy, Clone)] + pub struct TyCtxtEnsure<'tcx> { + pub tcx: TyCtxt<'tcx>, + } + + impl TyCtxtEnsure<$tcx> { + $($(#[$attr])* + #[inline(always)] + pub fn $name(self, key: query_helper_param_ty!($($K)*)) { + ensure_query::<queries::$name<'_>, _>(self.tcx, key.into_query_param()) + })* + } + + #[derive(Copy, Clone)] + pub struct TyCtxtAt<'tcx> { + pub tcx: TyCtxt<'tcx>, + pub span: Span, + } + + impl Deref for TyCtxtAt<'tcx> { + type Target = TyCtxt<'tcx>; + #[inline(always)] + fn deref(&self) -> &Self::Target { + &self.tcx + } + } + + impl TyCtxt<$tcx> { + /// Returns a transparent wrapper for `TyCtxt`, which ensures queries + /// are executed instead of just returning their results. + #[inline(always)] + pub fn ensure(self) -> TyCtxtEnsure<$tcx> { + TyCtxtEnsure { + tcx: self, + } + } + + /// Returns a transparent wrapper for `TyCtxt` which uses + /// `span` as the location of queries performed through it. + #[inline(always)] + pub fn at(self, span: Span) -> TyCtxtAt<$tcx> { + TyCtxtAt { + tcx: self, + span + } + } + + $($(#[$attr])* + #[inline(always)] + #[must_use] + pub fn $name(self, key: query_helper_param_ty!($($K)*)) + -> <queries::$name<$tcx> as QueryConfig<TyCtxt<$tcx>>>::Stored + { + self.at(DUMMY_SP).$name(key.into_query_param()) + })* + + /// All self-profiling events generated by the query engine use + /// virtual `StringId`s for their `event_id`. This method makes all + /// those virtual `StringId`s point to actual strings. + /// + /// If we are recording only summary data, the ids will point to + /// just the query names. If we are recording query keys too, we + /// allocate the corresponding strings here. + pub fn alloc_self_profile_query_strings(self) { + use crate::ty::query::profiling_support::{ + alloc_self_profile_query_strings_for_query_cache, + QueryKeyStringCache, + }; + + if !self.prof.enabled() { + return; + } + + let mut string_cache = QueryKeyStringCache::new(); + + $({ + alloc_self_profile_query_strings_for_query_cache( + self, + stringify!($name), + &self.queries.$name, + &mut string_cache, + ); + })* + } + } + + impl TyCtxtAt<$tcx> { + $($(#[$attr])* + #[inline(always)] + pub fn $name(self, key: query_helper_param_ty!($($K)*)) + -> <queries::$name<$tcx> as QueryConfig<TyCtxt<$tcx>>>::Stored + { + get_query::<queries::$name<'_>, _>(self.tcx, self.span, key.into_query_param()) + })* + } + + define_provider_struct! { + tcx: $tcx, + input: ($(([$($modifiers)*] [$name] [$($K)*] [$V]))*) + } + + impl Copy for Providers {} + impl Clone for Providers { + fn clone(&self) -> Self { *self } + } + } +} + +// FIXME(eddyb) this macro (and others?) use `$tcx` and `'tcx` interchangeably. +// We should either not take `$tcx` at all and use `'tcx` everywhere, or use +// `$tcx` everywhere (even if that isn't necessary due to lack of hygiene). +macro_rules! define_queries_struct { + (tcx: $tcx:tt, + input: ($(([$($modifiers:tt)*] [$($attr:tt)*] [$name:ident]))*)) => { + pub struct Queries<$tcx> { + /// This provides access to the incrimental comilation on-disk cache for query results. + /// Do not access this directly. It is only meant to be used by + /// `DepGraph::try_mark_green()` and the query infrastructure. + pub(crate) on_disk_cache: OnDiskCache<'tcx>, + + providers: IndexVec<CrateNum, Providers>, + fallback_extern_providers: Box<Providers>, + + $($(#[$attr])* $name: QueryState< + TyCtxt<$tcx>, + <queries::$name<$tcx> as QueryAccessors<TyCtxt<'tcx>>>::Cache, + >,)* + } + + impl<$tcx> Queries<$tcx> { + pub(crate) fn new( + providers: IndexVec<CrateNum, Providers>, + fallback_extern_providers: Providers, + on_disk_cache: OnDiskCache<'tcx>, + ) -> Self { + Queries { + providers, + fallback_extern_providers: Box::new(fallback_extern_providers), + on_disk_cache, + $($name: Default::default()),* + } + } + + pub(crate) fn try_collect_active_jobs( + &self + ) -> Option<FxHashMap<QueryJobId<crate::dep_graph::DepKind>, QueryJobInfo<TyCtxt<'tcx>>>> { + let mut jobs = FxHashMap::default(); + + $( + self.$name.try_collect_active_jobs( + <queries::$name<'tcx> as QueryAccessors<TyCtxt<'tcx>>>::DEP_KIND, + Query::$name, + &mut jobs, + )?; + )* + + Some(jobs) + } + } + }; +} + +macro_rules! define_provider_struct { + (tcx: $tcx:tt, + input: ($(([$($modifiers:tt)*] [$name:ident] [$K:ty] [$R:ty]))*)) => { + pub struct Providers { + $(pub $name: for<$tcx> fn(TyCtxt<$tcx>, $K) -> $R,)* + } + + impl Default for Providers { + fn default() -> Self { + $(fn $name<$tcx>(_: TyCtxt<$tcx>, key: $K) -> $R { + bug!("`tcx.{}({:?})` unsupported by its crate", + stringify!($name), key); + })* + Providers { $($name),* } + } + } + }; +} diff --git a/compiler/rustc_middle/src/ty/query/profiling_support.rs b/compiler/rustc_middle/src/ty/query/profiling_support.rs new file mode 100644 index 00000000000..9b1837356e3 --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/profiling_support.rs @@ -0,0 +1,287 @@ +use crate::ty::context::TyCtxt; +use crate::ty::WithOptConstParam; +use measureme::{StringComponent, StringId}; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::profiling::SelfProfiler; +use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE}; +use rustc_hir::definitions::DefPathData; +use rustc_query_system::query::QueryCache; +use rustc_query_system::query::QueryState; +use std::fmt::Debug; +use std::io::Write; + +pub struct QueryKeyStringCache { + def_id_cache: FxHashMap<DefId, StringId>, +} + +impl QueryKeyStringCache { + pub fn new() -> QueryKeyStringCache { + QueryKeyStringCache { def_id_cache: Default::default() } + } +} + +pub struct QueryKeyStringBuilder<'p, 'c, 'tcx> { + profiler: &'p SelfProfiler, + tcx: TyCtxt<'tcx>, + string_cache: &'c mut QueryKeyStringCache, +} + +impl<'p, 'c, 'tcx> QueryKeyStringBuilder<'p, 'c, 'tcx> { + pub fn new( + profiler: &'p SelfProfiler, + tcx: TyCtxt<'tcx>, + string_cache: &'c mut QueryKeyStringCache, + ) -> QueryKeyStringBuilder<'p, 'c, 'tcx> { + QueryKeyStringBuilder { profiler, tcx, string_cache } + } + + // The current implementation is rather crude. In the future it might be a + // good idea to base this on `ty::print` in order to get nicer and more + // efficient query keys. + fn def_id_to_string_id(&mut self, def_id: DefId) -> StringId { + if let Some(&string_id) = self.string_cache.def_id_cache.get(&def_id) { + return string_id; + } + + let def_key = self.tcx.def_key(def_id); + + let (parent_string_id, start_index) = match def_key.parent { + Some(parent_index) => { + let parent_def_id = DefId { index: parent_index, krate: def_id.krate }; + + (self.def_id_to_string_id(parent_def_id), 0) + } + None => (StringId::INVALID, 2), + }; + + let dis_buffer = &mut [0u8; 16]; + let name; + let dis; + let end_index; + + match def_key.disambiguated_data.data { + DefPathData::CrateRoot => { + name = self.tcx.original_crate_name(def_id.krate); + dis = ""; + end_index = 3; + } + other => { + name = other.as_symbol(); + if def_key.disambiguated_data.disambiguator == 0 { + dis = ""; + end_index = 3; + } else { + write!(&mut dis_buffer[..], "[{}]", def_key.disambiguated_data.disambiguator) + .unwrap(); + let end_of_dis = dis_buffer.iter().position(|&c| c == b']').unwrap(); + dis = std::str::from_utf8(&dis_buffer[..end_of_dis + 1]).unwrap(); + end_index = 4; + } + } + } + + let name = &*name.as_str(); + let components = [ + StringComponent::Ref(parent_string_id), + StringComponent::Value("::"), + StringComponent::Value(name), + StringComponent::Value(dis), + ]; + + let string_id = self.profiler.alloc_string(&components[start_index..end_index]); + + self.string_cache.def_id_cache.insert(def_id, string_id); + + string_id + } +} + +pub trait IntoSelfProfilingString { + fn to_self_profile_string(&self, builder: &mut QueryKeyStringBuilder<'_, '_, '_>) -> StringId; +} + +// The default implementation of `IntoSelfProfilingString` just uses `Debug` +// which is slow and causes lots of duplication of string data. +// The specialized impls below take care of making the `DefId` case more +// efficient. +impl<T: Debug> IntoSelfProfilingString for T { + default fn to_self_profile_string( + &self, + builder: &mut QueryKeyStringBuilder<'_, '_, '_>, + ) -> StringId { + let s = format!("{:?}", self); + builder.profiler.alloc_string(&s[..]) + } +} + +impl<T: SpecIntoSelfProfilingString> IntoSelfProfilingString for T { + fn to_self_profile_string(&self, builder: &mut QueryKeyStringBuilder<'_, '_, '_>) -> StringId { + self.spec_to_self_profile_string(builder) + } +} + +#[rustc_specialization_trait] +pub trait SpecIntoSelfProfilingString: Debug { + fn spec_to_self_profile_string( + &self, + builder: &mut QueryKeyStringBuilder<'_, '_, '_>, + ) -> StringId; +} + +impl SpecIntoSelfProfilingString for DefId { + fn spec_to_self_profile_string( + &self, + builder: &mut QueryKeyStringBuilder<'_, '_, '_>, + ) -> StringId { + builder.def_id_to_string_id(*self) + } +} + +impl SpecIntoSelfProfilingString for CrateNum { + fn spec_to_self_profile_string( + &self, + builder: &mut QueryKeyStringBuilder<'_, '_, '_>, + ) -> StringId { + builder.def_id_to_string_id(DefId { krate: *self, index: CRATE_DEF_INDEX }) + } +} + +impl SpecIntoSelfProfilingString for DefIndex { + fn spec_to_self_profile_string( + &self, + builder: &mut QueryKeyStringBuilder<'_, '_, '_>, + ) -> StringId { + builder.def_id_to_string_id(DefId { krate: LOCAL_CRATE, index: *self }) + } +} + +impl SpecIntoSelfProfilingString for LocalDefId { + fn spec_to_self_profile_string( + &self, + builder: &mut QueryKeyStringBuilder<'_, '_, '_>, + ) -> StringId { + builder.def_id_to_string_id(DefId { krate: LOCAL_CRATE, index: self.local_def_index }) + } +} + +impl<T: SpecIntoSelfProfilingString> SpecIntoSelfProfilingString for WithOptConstParam<T> { + fn spec_to_self_profile_string( + &self, + builder: &mut QueryKeyStringBuilder<'_, '_, '_>, + ) -> StringId { + // We print `WithOptConstParam` values as tuples to make them shorter + // and more readable, without losing information: + // + // "WithOptConstParam { did: foo::bar, const_param_did: Some(foo::baz) }" + // becomes "(foo::bar, foo::baz)" and + // "WithOptConstParam { did: foo::bar, const_param_did: None }" + // becomes "(foo::bar, _)". + + let did = StringComponent::Ref(self.did.to_self_profile_string(builder)); + + let const_param_did = if let Some(const_param_did) = self.const_param_did { + let const_param_did = builder.def_id_to_string_id(const_param_did); + StringComponent::Ref(const_param_did) + } else { + StringComponent::Value("_") + }; + + let components = [ + StringComponent::Value("("), + did, + StringComponent::Value(", "), + const_param_did, + StringComponent::Value(")"), + ]; + + builder.profiler.alloc_string(&components[..]) + } +} + +impl<T0, T1> SpecIntoSelfProfilingString for (T0, T1) +where + T0: SpecIntoSelfProfilingString, + T1: SpecIntoSelfProfilingString, +{ + fn spec_to_self_profile_string( + &self, + builder: &mut QueryKeyStringBuilder<'_, '_, '_>, + ) -> StringId { + let val0 = self.0.to_self_profile_string(builder); + let val1 = self.1.to_self_profile_string(builder); + + let components = &[ + StringComponent::Value("("), + StringComponent::Ref(val0), + StringComponent::Value(","), + StringComponent::Ref(val1), + StringComponent::Value(")"), + ]; + + builder.profiler.alloc_string(components) + } +} + +/// Allocate the self-profiling query strings for a single query cache. This +/// method is called from `alloc_self_profile_query_strings` which knows all +/// the queries via macro magic. +pub(super) fn alloc_self_profile_query_strings_for_query_cache<'tcx, C>( + tcx: TyCtxt<'tcx>, + query_name: &'static str, + query_state: &QueryState<TyCtxt<'tcx>, C>, + string_cache: &mut QueryKeyStringCache, +) where + C: QueryCache, + C::Key: Debug + Clone, +{ + tcx.prof.with_profiler(|profiler| { + let event_id_builder = profiler.event_id_builder(); + + // Walk the entire query cache and allocate the appropriate + // string representations. Each cache entry is uniquely + // identified by its dep_node_index. + if profiler.query_key_recording_enabled() { + let mut query_string_builder = QueryKeyStringBuilder::new(profiler, tcx, string_cache); + + let query_name = profiler.get_or_alloc_cached_string(query_name); + + // Since building the string representation of query keys might + // need to invoke queries itself, we cannot keep the query caches + // locked while doing so. Instead we copy out the + // `(query_key, dep_node_index)` pairs and release the lock again. + let query_keys_and_indices: Vec<_> = query_state + .iter_results(|results| results.map(|(k, _, i)| (k.clone(), i)).collect()); + + // Now actually allocate the strings. If allocating the strings + // generates new entries in the query cache, we'll miss them but + // we don't actually care. + for (query_key, dep_node_index) in query_keys_and_indices { + // Translate the DepNodeIndex into a QueryInvocationId + let query_invocation_id = dep_node_index.into(); + + // Create the string version of the query-key + let query_key = query_key.to_self_profile_string(&mut query_string_builder); + let event_id = event_id_builder.from_label_and_arg(query_name, query_key); + + // Doing this in bulk might be a good idea: + profiler.map_query_invocation_id_to_string( + query_invocation_id, + event_id.to_string_id(), + ); + } + } else { + // In this branch we don't allocate query keys + let query_name = profiler.get_or_alloc_cached_string(query_name); + let event_id = event_id_builder.from_label(query_name).to_string_id(); + + query_state.iter_results(|results| { + let query_invocation_ids: Vec<_> = results.map(|v| v.2.into()).collect(); + + profiler.bulk_map_query_invocation_id_to_single_string( + query_invocation_ids.into_iter(), + event_id, + ); + }); + } + }); +} diff --git a/compiler/rustc_middle/src/ty/query/stats.rs b/compiler/rustc_middle/src/ty/query/stats.rs new file mode 100644 index 00000000000..b496bf839ab --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/stats.rs @@ -0,0 +1,143 @@ +use crate::ty::query::queries; +use crate::ty::TyCtxt; +use rustc_hir::def_id::{DefId, LOCAL_CRATE}; +use rustc_query_system::query::QueryCache; +use rustc_query_system::query::QueryState; +use rustc_query_system::query::{QueryAccessors, QueryContext}; + +use std::any::type_name; +use std::mem; +#[cfg(debug_assertions)] +use std::sync::atomic::Ordering; + +trait KeyStats { + fn key_stats(&self, stats: &mut QueryStats); +} + +impl<T> KeyStats for T { + default fn key_stats(&self, _: &mut QueryStats) {} +} + +impl KeyStats for DefId { + fn key_stats(&self, stats: &mut QueryStats) { + if self.krate == LOCAL_CRATE { + stats.local_def_id_keys = Some(stats.local_def_id_keys.unwrap_or(0) + 1); + } + } +} + +#[derive(Clone)] +struct QueryStats { + name: &'static str, + cache_hits: usize, + key_size: usize, + key_type: &'static str, + value_size: usize, + value_type: &'static str, + entry_count: usize, + local_def_id_keys: Option<usize>, +} + +fn stats<CTX: QueryContext, C: QueryCache>( + name: &'static str, + map: &QueryState<CTX, C>, +) -> QueryStats { + let mut stats = QueryStats { + name, + #[cfg(debug_assertions)] + cache_hits: map.cache_hits.load(Ordering::Relaxed), + #[cfg(not(debug_assertions))] + cache_hits: 0, + key_size: mem::size_of::<C::Key>(), + key_type: type_name::<C::Key>(), + value_size: mem::size_of::<C::Value>(), + value_type: type_name::<C::Value>(), + entry_count: map.iter_results(|results| results.count()), + local_def_id_keys: None, + }; + map.iter_results(|results| { + for (key, _, _) in results { + key.key_stats(&mut stats) + } + }); + stats +} + +pub fn print_stats(tcx: TyCtxt<'_>) { + let queries = query_stats(tcx); + + if cfg!(debug_assertions) { + let hits: usize = queries.iter().map(|s| s.cache_hits).sum(); + let results: usize = queries.iter().map(|s| s.entry_count).sum(); + println!("\nQuery cache hit rate: {}", hits as f64 / (hits + results) as f64); + } + + let mut query_key_sizes = queries.clone(); + query_key_sizes.sort_by_key(|q| q.key_size); + println!("\nLarge query keys:"); + for q in query_key_sizes.iter().rev().filter(|q| q.key_size > 8) { + println!(" {} - {} x {} - {}", q.name, q.key_size, q.entry_count, q.key_type); + } + + let mut query_value_sizes = queries.clone(); + query_value_sizes.sort_by_key(|q| q.value_size); + println!("\nLarge query values:"); + for q in query_value_sizes.iter().rev().filter(|q| q.value_size > 8) { + println!(" {} - {} x {} - {}", q.name, q.value_size, q.entry_count, q.value_type); + } + + if cfg!(debug_assertions) { + let mut query_cache_hits = queries.clone(); + query_cache_hits.sort_by_key(|q| q.cache_hits); + println!("\nQuery cache hits:"); + for q in query_cache_hits.iter().rev() { + println!( + " {} - {} ({}%)", + q.name, + q.cache_hits, + q.cache_hits as f64 / (q.cache_hits + q.entry_count) as f64 + ); + } + } + + let mut query_value_count = queries.clone(); + query_value_count.sort_by_key(|q| q.entry_count); + println!("\nQuery value count:"); + for q in query_value_count.iter().rev() { + println!(" {} - {}", q.name, q.entry_count); + } + + let mut def_id_density: Vec<_> = + queries.iter().filter(|q| q.local_def_id_keys.is_some()).collect(); + def_id_density.sort_by_key(|q| q.local_def_id_keys.unwrap()); + println!("\nLocal DefId density:"); + let total = tcx.hir().definitions().def_index_count() as f64; + for q in def_id_density.iter().rev() { + let local = q.local_def_id_keys.unwrap(); + println!(" {} - {} = ({}%)", q.name, local, (local as f64 * 100.0) / total); + } +} + +macro_rules! print_stats { + (<$tcx:tt> $($category:tt { + $($(#[$attr:meta])* [$($modifiers:tt)*] fn $name:ident: $node:ident($K:ty) -> $V:ty,)* + },)*) => { + fn query_stats(tcx: TyCtxt<'_>) -> Vec<QueryStats> { + let mut queries = Vec::new(); + + $($( + queries.push(stats::< + TyCtxt<'_>, + <queries::$name<'_> as QueryAccessors<TyCtxt<'_>>>::Cache, + >( + stringify!($name), + &tcx.queries.$name, + )); + )*)* + + queries + } + } +} + +rustc_query_append! { [print_stats!][<'tcx>] } diff --git a/compiler/rustc_middle/src/ty/query/values.rs b/compiler/rustc_middle/src/ty/query/values.rs new file mode 100644 index 00000000000..f28b0f499f0 --- /dev/null +++ b/compiler/rustc_middle/src/ty/query/values.rs @@ -0,0 +1,44 @@ +use crate::ty::{self, AdtSizedConstraint, Ty, TyCtxt, TyS}; + +pub(super) trait Value<'tcx>: Sized { + fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self; +} + +impl<'tcx, T> Value<'tcx> for T { + default fn from_cycle_error(tcx: TyCtxt<'tcx>) -> T { + tcx.sess.abort_if_errors(); + bug!("Value::from_cycle_error called without errors"); + } +} + +impl<'tcx> Value<'tcx> for &'_ TyS<'_> { + fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self { + // SAFETY: This is never called when `Self` is not `Ty<'tcx>`. + // FIXME: Represent the above fact in the trait system somehow. + unsafe { std::mem::transmute::<Ty<'tcx>, Ty<'_>>(tcx.ty_error()) } + } +} + +impl<'tcx> Value<'tcx> for ty::SymbolName<'_> { + fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self { + // SAFETY: This is never called when `Self` is not `SymbolName<'tcx>`. + // FIXME: Represent the above fact in the trait system somehow. + unsafe { + std::mem::transmute::<ty::SymbolName<'tcx>, ty::SymbolName<'_>>(ty::SymbolName::new( + tcx, "<error>", + )) + } + } +} + +impl<'tcx> Value<'tcx> for AdtSizedConstraint<'_> { + fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self { + // SAFETY: This is never called when `Self` is not `AdtSizedConstraint<'tcx>`. + // FIXME: Represent the above fact in the trait system somehow. + unsafe { + std::mem::transmute::<AdtSizedConstraint<'tcx>, AdtSizedConstraint<'_>>( + AdtSizedConstraint(tcx.intern_type_list(&[tcx.ty_error()])), + ) + } + } +} diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs new file mode 100644 index 00000000000..ae2820b460f --- /dev/null +++ b/compiler/rustc_middle/src/ty/relate.rs @@ -0,0 +1,757 @@ +//! Generalized type relating mechanism. +//! +//! A type relation `R` relates a pair of values `(A, B)`. `A and B` are usually +//! types or regions but can be other things. Examples of type relations are +//! subtyping, type equality, etc. + +use crate::mir::interpret::{get_slice_bytes, ConstValue}; +use crate::ty::error::{ExpectedFound, TypeError}; +use crate::ty::subst::{GenericArg, GenericArgKind, SubstsRef}; +use crate::ty::{self, Ty, TyCtxt, TypeFoldable}; +use rustc_hir as ast; +use rustc_hir::def_id::DefId; +use rustc_span::DUMMY_SP; +use rustc_target::spec::abi; +use std::iter; + +pub type RelateResult<'tcx, T> = Result<T, TypeError<'tcx>>; + +#[derive(Clone, Debug)] +pub enum Cause { + ExistentialRegionBound, // relating an existential region bound +} + +pub trait TypeRelation<'tcx>: Sized { + fn tcx(&self) -> TyCtxt<'tcx>; + + fn param_env(&self) -> ty::ParamEnv<'tcx>; + + /// Returns a static string we can use for printouts. + fn tag(&self) -> &'static str; + + /// Returns `true` if the value `a` is the "expected" type in the + /// relation. Just affects error messages. + fn a_is_expected(&self) -> bool; + + fn with_cause<F, R>(&mut self, _cause: Cause, f: F) -> R + where + F: FnOnce(&mut Self) -> R, + { + f(self) + } + + /// Generic relation routine suitable for most anything. + fn relate<T: Relate<'tcx>>(&mut self, a: T, b: T) -> RelateResult<'tcx, T> { + Relate::relate(self, a, b) + } + + /// Relate the two substitutions for the given item. The default + /// is to look up the variance for the item and proceed + /// accordingly. + fn relate_item_substs( + &mut self, + item_def_id: DefId, + a_subst: SubstsRef<'tcx>, + b_subst: SubstsRef<'tcx>, + ) -> RelateResult<'tcx, SubstsRef<'tcx>> { + debug!( + "relate_item_substs(item_def_id={:?}, a_subst={:?}, b_subst={:?})", + item_def_id, a_subst, b_subst + ); + + let opt_variances = self.tcx().variances_of(item_def_id); + relate_substs(self, Some(opt_variances), a_subst, b_subst) + } + + /// Switch variance for the purpose of relating `a` and `b`. + fn relate_with_variance<T: Relate<'tcx>>( + &mut self, + variance: ty::Variance, + a: T, + b: T, + ) -> RelateResult<'tcx, T>; + + // Overridable relations. You shouldn't typically call these + // directly, instead call `relate()`, which in turn calls + // these. This is both more uniform but also allows us to add + // additional hooks for other types in the future if needed + // without making older code, which called `relate`, obsolete. + + fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>>; + + fn regions( + &mut self, + a: ty::Region<'tcx>, + b: ty::Region<'tcx>, + ) -> RelateResult<'tcx, ty::Region<'tcx>>; + + fn consts( + &mut self, + a: &'tcx ty::Const<'tcx>, + b: &'tcx ty::Const<'tcx>, + ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>>; + + fn binders<T>( + &mut self, + a: ty::Binder<T>, + b: ty::Binder<T>, + ) -> RelateResult<'tcx, ty::Binder<T>> + where + T: Relate<'tcx>; +} + +pub trait Relate<'tcx>: TypeFoldable<'tcx> + Copy { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: Self, + b: Self, + ) -> RelateResult<'tcx, Self>; +} + +/////////////////////////////////////////////////////////////////////////// +// Relate impls + +impl<'tcx> Relate<'tcx> for ty::TypeAndMut<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::TypeAndMut<'tcx>, + b: ty::TypeAndMut<'tcx>, + ) -> RelateResult<'tcx, ty::TypeAndMut<'tcx>> { + debug!("{}.mts({:?}, {:?})", relation.tag(), a, b); + if a.mutbl != b.mutbl { + Err(TypeError::Mutability) + } else { + let mutbl = a.mutbl; + let variance = match mutbl { + ast::Mutability::Not => ty::Covariant, + ast::Mutability::Mut => ty::Invariant, + }; + let ty = relation.relate_with_variance(variance, a.ty, b.ty)?; + Ok(ty::TypeAndMut { ty, mutbl }) + } + } +} + +pub fn relate_substs<R: TypeRelation<'tcx>>( + relation: &mut R, + variances: Option<&[ty::Variance]>, + a_subst: SubstsRef<'tcx>, + b_subst: SubstsRef<'tcx>, +) -> RelateResult<'tcx, SubstsRef<'tcx>> { + let tcx = relation.tcx(); + + let params = a_subst.iter().zip(b_subst).enumerate().map(|(i, (a, b))| { + let variance = variances.map_or(ty::Invariant, |v| v[i]); + relation.relate_with_variance(variance, a, b) + }); + + Ok(tcx.mk_substs(params)?) +} + +impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::FnSig<'tcx>, + b: ty::FnSig<'tcx>, + ) -> RelateResult<'tcx, ty::FnSig<'tcx>> { + let tcx = relation.tcx(); + + if a.c_variadic != b.c_variadic { + return Err(TypeError::VariadicMismatch(expected_found( + relation, + a.c_variadic, + b.c_variadic, + ))); + } + let unsafety = relation.relate(a.unsafety, b.unsafety)?; + let abi = relation.relate(a.abi, b.abi)?; + + if a.inputs().len() != b.inputs().len() { + return Err(TypeError::ArgCount); + } + + let inputs_and_output = a + .inputs() + .iter() + .cloned() + .zip(b.inputs().iter().cloned()) + .map(|x| (x, false)) + .chain(iter::once(((a.output(), b.output()), true))) + .map(|((a, b), is_output)| { + if is_output { + relation.relate(a, b) + } else { + relation.relate_with_variance(ty::Contravariant, a, b) + } + }); + Ok(ty::FnSig { + inputs_and_output: tcx.mk_type_list(inputs_and_output)?, + c_variadic: a.c_variadic, + unsafety, + abi, + }) + } +} + +impl<'tcx> Relate<'tcx> for ast::Unsafety { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ast::Unsafety, + b: ast::Unsafety, + ) -> RelateResult<'tcx, ast::Unsafety> { + if a != b { + Err(TypeError::UnsafetyMismatch(expected_found(relation, a, b))) + } else { + Ok(a) + } + } +} + +impl<'tcx> Relate<'tcx> for abi::Abi { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: abi::Abi, + b: abi::Abi, + ) -> RelateResult<'tcx, abi::Abi> { + if a == b { Ok(a) } else { Err(TypeError::AbiMismatch(expected_found(relation, a, b))) } + } +} + +impl<'tcx> Relate<'tcx> for ty::ProjectionTy<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::ProjectionTy<'tcx>, + b: ty::ProjectionTy<'tcx>, + ) -> RelateResult<'tcx, ty::ProjectionTy<'tcx>> { + if a.item_def_id != b.item_def_id { + Err(TypeError::ProjectionMismatched(expected_found( + relation, + a.item_def_id, + b.item_def_id, + ))) + } else { + let substs = relation.relate(a.substs, b.substs)?; + Ok(ty::ProjectionTy { item_def_id: a.item_def_id, substs: &substs }) + } + } +} + +impl<'tcx> Relate<'tcx> for ty::ExistentialProjection<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::ExistentialProjection<'tcx>, + b: ty::ExistentialProjection<'tcx>, + ) -> RelateResult<'tcx, ty::ExistentialProjection<'tcx>> { + if a.item_def_id != b.item_def_id { + Err(TypeError::ProjectionMismatched(expected_found( + relation, + a.item_def_id, + b.item_def_id, + ))) + } else { + let ty = relation.relate_with_variance(ty::Invariant, a.ty, b.ty)?; + let substs = relation.relate_with_variance(ty::Invariant, a.substs, b.substs)?; + Ok(ty::ExistentialProjection { item_def_id: a.item_def_id, substs, ty }) + } + } +} + +impl<'tcx> Relate<'tcx> for ty::TraitRef<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::TraitRef<'tcx>, + b: ty::TraitRef<'tcx>, + ) -> RelateResult<'tcx, ty::TraitRef<'tcx>> { + // Different traits cannot be related. + if a.def_id != b.def_id { + Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id))) + } else { + let substs = relate_substs(relation, None, a.substs, b.substs)?; + Ok(ty::TraitRef { def_id: a.def_id, substs }) + } + } +} + +impl<'tcx> Relate<'tcx> for ty::ExistentialTraitRef<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::ExistentialTraitRef<'tcx>, + b: ty::ExistentialTraitRef<'tcx>, + ) -> RelateResult<'tcx, ty::ExistentialTraitRef<'tcx>> { + // Different traits cannot be related. + if a.def_id != b.def_id { + Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id))) + } else { + let substs = relate_substs(relation, None, a.substs, b.substs)?; + Ok(ty::ExistentialTraitRef { def_id: a.def_id, substs }) + } + } +} + +#[derive(Copy, Debug, Clone, TypeFoldable)] +struct GeneratorWitness<'tcx>(&'tcx ty::List<Ty<'tcx>>); + +impl<'tcx> Relate<'tcx> for GeneratorWitness<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: GeneratorWitness<'tcx>, + b: GeneratorWitness<'tcx>, + ) -> RelateResult<'tcx, GeneratorWitness<'tcx>> { + assert_eq!(a.0.len(), b.0.len()); + let tcx = relation.tcx(); + let types = tcx.mk_type_list(a.0.iter().zip(b.0).map(|(a, b)| relation.relate(a, b)))?; + Ok(GeneratorWitness(types)) + } +} + +impl<'tcx> Relate<'tcx> for Ty<'tcx> { + #[inline] + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: Ty<'tcx>, + b: Ty<'tcx>, + ) -> RelateResult<'tcx, Ty<'tcx>> { + relation.tys(a, b) + } +} + +/// The main "type relation" routine. Note that this does not handle +/// inference artifacts, so you should filter those out before calling +/// it. +pub fn super_relate_tys<R: TypeRelation<'tcx>>( + relation: &mut R, + a: Ty<'tcx>, + b: Ty<'tcx>, +) -> RelateResult<'tcx, Ty<'tcx>> { + let tcx = relation.tcx(); + debug!("super_relate_tys: a={:?} b={:?}", a, b); + match (&a.kind, &b.kind) { + (&ty::Infer(_), _) | (_, &ty::Infer(_)) => { + // The caller should handle these cases! + bug!("var types encountered in super_relate_tys") + } + + (ty::Bound(..), _) | (_, ty::Bound(..)) => { + bug!("bound types encountered in super_relate_tys") + } + + (&ty::Error(_), _) | (_, &ty::Error(_)) => Ok(tcx.ty_error()), + + (&ty::Never, _) + | (&ty::Char, _) + | (&ty::Bool, _) + | (&ty::Int(_), _) + | (&ty::Uint(_), _) + | (&ty::Float(_), _) + | (&ty::Str, _) + if a == b => + { + Ok(a) + } + + (&ty::Param(ref a_p), &ty::Param(ref b_p)) if a_p.index == b_p.index => Ok(a), + + (ty::Placeholder(p1), ty::Placeholder(p2)) if p1 == p2 => Ok(a), + + (&ty::Adt(a_def, a_substs), &ty::Adt(b_def, b_substs)) if a_def == b_def => { + let substs = relation.relate_item_substs(a_def.did, a_substs, b_substs)?; + Ok(tcx.mk_adt(a_def, substs)) + } + + (&ty::Foreign(a_id), &ty::Foreign(b_id)) if a_id == b_id => Ok(tcx.mk_foreign(a_id)), + + (&ty::Dynamic(a_obj, a_region), &ty::Dynamic(b_obj, b_region)) => { + let region_bound = relation.with_cause(Cause::ExistentialRegionBound, |relation| { + relation.relate_with_variance(ty::Contravariant, a_region, b_region) + })?; + Ok(tcx.mk_dynamic(relation.relate(a_obj, b_obj)?, region_bound)) + } + + (&ty::Generator(a_id, a_substs, movability), &ty::Generator(b_id, b_substs, _)) + if a_id == b_id => + { + // All Generator types with the same id represent + // the (anonymous) type of the same generator expression. So + // all of their regions should be equated. + let substs = relation.relate(a_substs, b_substs)?; + Ok(tcx.mk_generator(a_id, substs, movability)) + } + + (&ty::GeneratorWitness(a_types), &ty::GeneratorWitness(b_types)) => { + // Wrap our types with a temporary GeneratorWitness struct + // inside the binder so we can related them + let a_types = a_types.map_bound(GeneratorWitness); + let b_types = b_types.map_bound(GeneratorWitness); + // Then remove the GeneratorWitness for the result + let types = relation.relate(a_types, b_types)?.map_bound(|witness| witness.0); + Ok(tcx.mk_generator_witness(types)) + } + + (&ty::Closure(a_id, a_substs), &ty::Closure(b_id, b_substs)) if a_id == b_id => { + // All Closure types with the same id represent + // the (anonymous) type of the same closure expression. So + // all of their regions should be equated. + let substs = relation.relate(a_substs, b_substs)?; + Ok(tcx.mk_closure(a_id, &substs)) + } + + (&ty::RawPtr(a_mt), &ty::RawPtr(b_mt)) => { + let mt = relation.relate(a_mt, b_mt)?; + Ok(tcx.mk_ptr(mt)) + } + + (&ty::Ref(a_r, a_ty, a_mutbl), &ty::Ref(b_r, b_ty, b_mutbl)) => { + let r = relation.relate_with_variance(ty::Contravariant, a_r, b_r)?; + let a_mt = ty::TypeAndMut { ty: a_ty, mutbl: a_mutbl }; + let b_mt = ty::TypeAndMut { ty: b_ty, mutbl: b_mutbl }; + let mt = relation.relate(a_mt, b_mt)?; + Ok(tcx.mk_ref(r, mt)) + } + + (&ty::Array(a_t, sz_a), &ty::Array(b_t, sz_b)) => { + let t = relation.relate(a_t, b_t)?; + match relation.relate(sz_a, sz_b) { + Ok(sz) => Ok(tcx.mk_ty(ty::Array(t, sz))), + // FIXME(#72219) Implement improved diagnostics for mismatched array + // length? + Err(err) if relation.tcx().lazy_normalization() => Err(err), + Err(err) => { + // Check whether the lengths are both concrete/known values, + // but are unequal, for better diagnostics. + let sz_a = sz_a.try_eval_usize(tcx, relation.param_env()); + let sz_b = sz_b.try_eval_usize(tcx, relation.param_env()); + match (sz_a, sz_b) { + (Some(sz_a_val), Some(sz_b_val)) => Err(TypeError::FixedArraySize( + expected_found(relation, sz_a_val, sz_b_val), + )), + _ => Err(err), + } + } + } + } + + (&ty::Slice(a_t), &ty::Slice(b_t)) => { + let t = relation.relate(a_t, b_t)?; + Ok(tcx.mk_slice(t)) + } + + (&ty::Tuple(as_), &ty::Tuple(bs)) => { + if as_.len() == bs.len() { + Ok(tcx.mk_tup( + as_.iter().zip(bs).map(|(a, b)| relation.relate(a.expect_ty(), b.expect_ty())), + )?) + } else if !(as_.is_empty() || bs.is_empty()) { + Err(TypeError::TupleSize(expected_found(relation, as_.len(), bs.len()))) + } else { + Err(TypeError::Sorts(expected_found(relation, a, b))) + } + } + + (&ty::FnDef(a_def_id, a_substs), &ty::FnDef(b_def_id, b_substs)) + if a_def_id == b_def_id => + { + let substs = relation.relate_item_substs(a_def_id, a_substs, b_substs)?; + Ok(tcx.mk_fn_def(a_def_id, substs)) + } + + (&ty::FnPtr(a_fty), &ty::FnPtr(b_fty)) => { + let fty = relation.relate(a_fty, b_fty)?; + Ok(tcx.mk_fn_ptr(fty)) + } + + // these two are already handled downstream in case of lazy normalization + (&ty::Projection(a_data), &ty::Projection(b_data)) => { + let projection_ty = relation.relate(a_data, b_data)?; + Ok(tcx.mk_projection(projection_ty.item_def_id, projection_ty.substs)) + } + + (&ty::Opaque(a_def_id, a_substs), &ty::Opaque(b_def_id, b_substs)) + if a_def_id == b_def_id => + { + let substs = relate_substs(relation, None, a_substs, b_substs)?; + Ok(tcx.mk_opaque(a_def_id, substs)) + } + + _ => Err(TypeError::Sorts(expected_found(relation, a, b))), + } +} + +/// The main "const relation" routine. Note that this does not handle +/// inference artifacts, so you should filter those out before calling +/// it. +pub fn super_relate_consts<R: TypeRelation<'tcx>>( + relation: &mut R, + a: &'tcx ty::Const<'tcx>, + b: &'tcx ty::Const<'tcx>, +) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> { + debug!("{}.super_relate_consts(a = {:?}, b = {:?})", relation.tag(), a, b); + let tcx = relation.tcx(); + + let eagerly_eval = |x: &'tcx ty::Const<'tcx>| x.eval(tcx, relation.param_env()).val; + + // FIXME(eddyb) doesn't look like everything below checks that `a.ty == b.ty`. + // We could probably always assert it early, as `const` generic parameters + // are not allowed to depend on other generic parameters, i.e. are concrete. + // (although there could be normalization differences) + + // Currently, the values that can be unified are primitive types, + // and those that derive both `PartialEq` and `Eq`, corresponding + // to structural-match types. + let new_const_val = match (eagerly_eval(a), eagerly_eval(b)) { + (ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => { + // The caller should handle these cases! + bug!("var types encountered in super_relate_consts: {:?} {:?}", a, b) + } + + (ty::ConstKind::Error(d), _) | (_, ty::ConstKind::Error(d)) => Ok(ty::ConstKind::Error(d)), + + (ty::ConstKind::Param(a_p), ty::ConstKind::Param(b_p)) if a_p.index == b_p.index => { + return Ok(a); + } + (ty::ConstKind::Placeholder(p1), ty::ConstKind::Placeholder(p2)) if p1 == p2 => { + return Ok(a); + } + (ty::ConstKind::Value(a_val), ty::ConstKind::Value(b_val)) => { + let new_val = match (a_val, b_val) { + (ConstValue::Scalar(a_val), ConstValue::Scalar(b_val)) if a.ty == b.ty => { + if a_val == b_val { + Ok(ConstValue::Scalar(a_val)) + } else if let ty::FnPtr(_) = a.ty.kind { + let a_instance = tcx.global_alloc(a_val.assert_ptr().alloc_id).unwrap_fn(); + let b_instance = tcx.global_alloc(b_val.assert_ptr().alloc_id).unwrap_fn(); + if a_instance == b_instance { + Ok(ConstValue::Scalar(a_val)) + } else { + Err(TypeError::ConstMismatch(expected_found(relation, a, b))) + } + } else { + Err(TypeError::ConstMismatch(expected_found(relation, a, b))) + } + } + + (ConstValue::Slice { .. }, ConstValue::Slice { .. }) => { + let a_bytes = get_slice_bytes(&tcx, a_val); + let b_bytes = get_slice_bytes(&tcx, b_val); + if a_bytes == b_bytes { + Ok(a_val) + } else { + Err(TypeError::ConstMismatch(expected_found(relation, a, b))) + } + } + + (ConstValue::ByRef { .. }, ConstValue::ByRef { .. }) => { + match a.ty.kind { + ty::Array(..) | ty::Adt(..) | ty::Tuple(..) => { + let a_destructured = tcx.destructure_const(relation.param_env().and(a)); + let b_destructured = tcx.destructure_const(relation.param_env().and(b)); + + // Both the variant and each field have to be equal. + if a_destructured.variant == b_destructured.variant { + for (a_field, b_field) in + a_destructured.fields.iter().zip(b_destructured.fields.iter()) + { + relation.consts(a_field, b_field)?; + } + + Ok(a_val) + } else { + Err(TypeError::ConstMismatch(expected_found(relation, a, b))) + } + } + // FIXME(const_generics): There are probably some `TyKind`s + // which should be handled here. + _ => { + tcx.sess.delay_span_bug( + DUMMY_SP, + &format!("unexpected consts: a: {:?}, b: {:?}", a, b), + ); + Err(TypeError::ConstMismatch(expected_found(relation, a, b))) + } + } + } + + _ => Err(TypeError::ConstMismatch(expected_found(relation, a, b))), + }; + + new_val.map(ty::ConstKind::Value) + } + + // FIXME(const_generics): this is wrong, as it is a projection + ( + ty::ConstKind::Unevaluated(a_def, a_substs, a_promoted), + ty::ConstKind::Unevaluated(b_def, b_substs, b_promoted), + ) if a_def == b_def && a_promoted == b_promoted => { + let substs = + relation.relate_with_variance(ty::Variance::Invariant, a_substs, b_substs)?; + Ok(ty::ConstKind::Unevaluated(a_def, substs, a_promoted)) + } + _ => Err(TypeError::ConstMismatch(expected_found(relation, a, b))), + }; + new_const_val.map(|val| tcx.mk_const(ty::Const { val, ty: a.ty })) +} + +impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::ExistentialPredicate<'tcx>> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: Self, + b: Self, + ) -> RelateResult<'tcx, Self> { + let tcx = relation.tcx(); + + // FIXME: this is wasteful, but want to do a perf run to see how slow it is. + // We need to perform this deduplication as we sometimes generate duplicate projections + // in `a`. + let mut a_v: Vec<_> = a.into_iter().collect(); + let mut b_v: Vec<_> = b.into_iter().collect(); + a_v.sort_by(|a, b| a.stable_cmp(tcx, b)); + a_v.dedup(); + b_v.sort_by(|a, b| a.stable_cmp(tcx, b)); + b_v.dedup(); + if a_v.len() != b_v.len() { + return Err(TypeError::ExistentialMismatch(expected_found(relation, a, b))); + } + + let v = a_v.into_iter().zip(b_v.into_iter()).map(|(ep_a, ep_b)| { + use crate::ty::ExistentialPredicate::*; + match (ep_a, ep_b) { + (Trait(a), Trait(b)) => Ok(Trait(relation.relate(a, b)?)), + (Projection(a), Projection(b)) => Ok(Projection(relation.relate(a, b)?)), + (AutoTrait(a), AutoTrait(b)) if a == b => Ok(AutoTrait(a)), + _ => Err(TypeError::ExistentialMismatch(expected_found(relation, a, b))), + } + }); + Ok(tcx.mk_existential_predicates(v)?) + } +} + +impl<'tcx> Relate<'tcx> for ty::ClosureSubsts<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::ClosureSubsts<'tcx>, + b: ty::ClosureSubsts<'tcx>, + ) -> RelateResult<'tcx, ty::ClosureSubsts<'tcx>> { + let substs = relate_substs(relation, None, a.substs, b.substs)?; + Ok(ty::ClosureSubsts { substs }) + } +} + +impl<'tcx> Relate<'tcx> for ty::GeneratorSubsts<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::GeneratorSubsts<'tcx>, + b: ty::GeneratorSubsts<'tcx>, + ) -> RelateResult<'tcx, ty::GeneratorSubsts<'tcx>> { + let substs = relate_substs(relation, None, a.substs, b.substs)?; + Ok(ty::GeneratorSubsts { substs }) + } +} + +impl<'tcx> Relate<'tcx> for SubstsRef<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: SubstsRef<'tcx>, + b: SubstsRef<'tcx>, + ) -> RelateResult<'tcx, SubstsRef<'tcx>> { + relate_substs(relation, None, a, b) + } +} + +impl<'tcx> Relate<'tcx> for ty::Region<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::Region<'tcx>, + b: ty::Region<'tcx>, + ) -> RelateResult<'tcx, ty::Region<'tcx>> { + relation.regions(a, b) + } +} + +impl<'tcx> Relate<'tcx> for &'tcx ty::Const<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: &'tcx ty::Const<'tcx>, + b: &'tcx ty::Const<'tcx>, + ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> { + relation.consts(a, b) + } +} + +impl<'tcx, T: Relate<'tcx>> Relate<'tcx> for ty::Binder<T> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::Binder<T>, + b: ty::Binder<T>, + ) -> RelateResult<'tcx, ty::Binder<T>> { + relation.binders(a, b) + } +} + +impl<'tcx> Relate<'tcx> for GenericArg<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: GenericArg<'tcx>, + b: GenericArg<'tcx>, + ) -> RelateResult<'tcx, GenericArg<'tcx>> { + match (a.unpack(), b.unpack()) { + (GenericArgKind::Lifetime(a_lt), GenericArgKind::Lifetime(b_lt)) => { + Ok(relation.relate(a_lt, b_lt)?.into()) + } + (GenericArgKind::Type(a_ty), GenericArgKind::Type(b_ty)) => { + Ok(relation.relate(a_ty, b_ty)?.into()) + } + (GenericArgKind::Const(a_ct), GenericArgKind::Const(b_ct)) => { + Ok(relation.relate(a_ct, b_ct)?.into()) + } + (GenericArgKind::Lifetime(unpacked), x) => { + bug!("impossible case reached: can't relate: {:?} with {:?}", unpacked, x) + } + (GenericArgKind::Type(unpacked), x) => { + bug!("impossible case reached: can't relate: {:?} with {:?}", unpacked, x) + } + (GenericArgKind::Const(unpacked), x) => { + bug!("impossible case reached: can't relate: {:?} with {:?}", unpacked, x) + } + } + } +} + +impl<'tcx> Relate<'tcx> for ty::TraitPredicate<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::TraitPredicate<'tcx>, + b: ty::TraitPredicate<'tcx>, + ) -> RelateResult<'tcx, ty::TraitPredicate<'tcx>> { + Ok(ty::TraitPredicate { trait_ref: relation.relate(a.trait_ref, b.trait_ref)? }) + } +} + +impl<'tcx> Relate<'tcx> for ty::ProjectionPredicate<'tcx> { + fn relate<R: TypeRelation<'tcx>>( + relation: &mut R, + a: ty::ProjectionPredicate<'tcx>, + b: ty::ProjectionPredicate<'tcx>, + ) -> RelateResult<'tcx, ty::ProjectionPredicate<'tcx>> { + Ok(ty::ProjectionPredicate { + projection_ty: relation.relate(a.projection_ty, b.projection_ty)?, + ty: relation.relate(a.ty, b.ty)?, + }) + } +} + +/////////////////////////////////////////////////////////////////////////// +// Error handling + +pub fn expected_found<R, T>(relation: &mut R, a: T, b: T) -> ExpectedFound<T> +where + R: TypeRelation<'tcx>, +{ + expected_found_bool(relation.a_is_expected(), a, b) +} + +pub fn expected_found_bool<T>(a_is_expected: bool, a: T, b: T) -> ExpectedFound<T> { + if a_is_expected { + ExpectedFound { expected: a, found: b } + } else { + ExpectedFound { expected: b, found: a } + } +} diff --git a/compiler/rustc_middle/src/ty/steal.rs b/compiler/rustc_middle/src/ty/steal.rs new file mode 100644 index 00000000000..224e76845d7 --- /dev/null +++ b/compiler/rustc_middle/src/ty/steal.rs @@ -0,0 +1,44 @@ +use rustc_data_structures::sync::{MappedReadGuard, ReadGuard, RwLock}; + +/// The `Steal` struct is intended to used as the value for a query. +/// Specifically, we sometimes have queries (*cough* MIR *cough*) +/// where we create a large, complex value that we want to iteratively +/// update (e.g., optimize). We could clone the value for each +/// optimization, but that'd be expensive. And yet we don't just want +/// to mutate it in place, because that would spoil the idea that +/// queries are these pure functions that produce an immutable value +/// (since if you did the query twice, you could observe the mutations). +/// So instead we have the query produce a `&'tcx Steal<mir::Body<'tcx>>` +/// (to be very specific). Now we can read from this +/// as much as we want (using `borrow()`), but you can also +/// `steal()`. Once you steal, any further attempt to read will panic. +/// Therefore, we know that -- assuming no ICE -- nobody is observing +/// the fact that the MIR was updated. +/// +/// Obviously, whenever you have a query that yields a `Steal` value, +/// you must treat it with caution, and make sure that you know that +/// -- once the value is stolen -- it will never be read from again. +// +// FIXME(#41710): what is the best way to model linear queries? +pub struct Steal<T> { + value: RwLock<Option<T>>, +} + +impl<T> Steal<T> { + pub fn new(value: T) -> Self { + Steal { value: RwLock::new(Some(value)) } + } + + pub fn borrow(&self) -> MappedReadGuard<'_, T> { + ReadGuard::map(self.value.borrow(), |opt| match *opt { + None => bug!("attempted to read from stolen value"), + Some(ref v) => v, + }) + } + + pub fn steal(&self) -> T { + let value_ref = &mut *self.value.try_write().expect("stealing value which is locked"); + let value = value_ref.take(); + value.expect("attempt to read from stolen value") + } +} diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs new file mode 100644 index 00000000000..605e3545dea --- /dev/null +++ b/compiler/rustc_middle/src/ty/structural_impls.rs @@ -0,0 +1,1166 @@ +//! This module contains implements of the `Lift` and `TypeFoldable` +//! traits for various types in the Rust compiler. Most are written by +//! hand, though we've recently added some macros and proc-macros to help with the tedium. + +use crate::mir::interpret; +use crate::mir::ProjectionKind; +use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor}; +use crate::ty::print::{FmtPrinter, Printer}; +use crate::ty::{self, InferConst, Lift, Ty, TyCtxt}; +use rustc_hir as hir; +use rustc_hir::def::Namespace; +use rustc_hir::def_id::CRATE_DEF_INDEX; +use rustc_index::vec::{Idx, IndexVec}; + +use smallvec::SmallVec; +use std::fmt; +use std::rc::Rc; +use std::sync::Arc; + +impl fmt::Debug for ty::TraitDef { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + ty::tls::with(|tcx| { + FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.def_id, &[])?; + Ok(()) + }) + } +} + +impl fmt::Debug for ty::AdtDef { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + ty::tls::with(|tcx| { + FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.did, &[])?; + Ok(()) + }) + } +} + +impl fmt::Debug for ty::UpvarId { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let name = ty::tls::with(|tcx| tcx.hir().name(self.var_path.hir_id)); + write!(f, "UpvarId({:?};`{}`;{:?})", self.var_path.hir_id, name, self.closure_expr_id) + } +} + +impl fmt::Debug for ty::UpvarBorrow<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "UpvarBorrow({:?}, {:?})", self.kind, self.region) + } +} + +impl fmt::Debug for ty::ExistentialTraitRef<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(self, f) + } +} + +impl fmt::Debug for ty::adjustment::Adjustment<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "{:?} -> {}", self.kind, self.target) + } +} + +impl fmt::Debug for ty::BoundRegion { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + ty::BrAnon(n) => write!(f, "BrAnon({:?})", n), + ty::BrNamed(did, name) => { + if did.index == CRATE_DEF_INDEX { + write!(f, "BrNamed({})", name) + } else { + write!(f, "BrNamed({:?}, {})", did, name) + } + } + ty::BrEnv => write!(f, "BrEnv"), + } + } +} + +impl fmt::Debug for ty::RegionKind { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + ty::ReEarlyBound(ref data) => write!(f, "ReEarlyBound({}, {})", data.index, data.name), + + ty::ReLateBound(binder_id, ref bound_region) => { + write!(f, "ReLateBound({:?}, {:?})", binder_id, bound_region) + } + + ty::ReFree(ref fr) => fr.fmt(f), + + ty::ReStatic => write!(f, "ReStatic"), + + ty::ReVar(ref vid) => vid.fmt(f), + + ty::RePlaceholder(placeholder) => write!(f, "RePlaceholder({:?})", placeholder), + + ty::ReEmpty(ui) => write!(f, "ReEmpty({:?})", ui), + + ty::ReErased => write!(f, "ReErased"), + } + } +} + +impl fmt::Debug for ty::FreeRegion { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region) + } +} + +impl fmt::Debug for ty::Variance { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.write_str(match *self { + ty::Covariant => "+", + ty::Contravariant => "-", + ty::Invariant => "o", + ty::Bivariant => "*", + }) + } +} + +impl fmt::Debug for ty::FnSig<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output()) + } +} + +impl fmt::Debug for ty::TyVid { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "_#{}t", self.index) + } +} + +impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "_#{}c", self.index) + } +} + +impl fmt::Debug for ty::IntVid { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "_#{}i", self.index) + } +} + +impl fmt::Debug for ty::FloatVid { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "_#{}f", self.index) + } +} + +impl fmt::Debug for ty::RegionVid { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "'_#{}r", self.index()) + } +} + +impl fmt::Debug for ty::InferTy { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + ty::TyVar(ref v) => v.fmt(f), + ty::IntVar(ref v) => v.fmt(f), + ty::FloatVar(ref v) => v.fmt(f), + ty::FreshTy(v) => write!(f, "FreshTy({:?})", v), + ty::FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v), + ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v), + } + } +} + +impl fmt::Debug for ty::IntVarValue { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + ty::IntType(ref v) => v.fmt(f), + ty::UintType(ref v) => v.fmt(f), + } + } +} + +impl fmt::Debug for ty::FloatVarValue { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + self.0.fmt(f) + } +} + +impl fmt::Debug for ty::TraitRef<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(self, f) + } +} + +impl fmt::Debug for Ty<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(self, f) + } +} + +impl fmt::Debug for ty::ParamTy { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "{}/#{}", self.name, self.index) + } +} + +impl fmt::Debug for ty::ParamConst { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "{}/#{}", self.name, self.index) + } +} + +impl fmt::Debug for ty::TraitPredicate<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "TraitPredicate({:?})", self.trait_ref) + } +} + +impl fmt::Debug for ty::ProjectionPredicate<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.ty) + } +} + +impl fmt::Debug for ty::Predicate<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "{:?}", self.kind()) + } +} + +impl fmt::Debug for ty::PredicateKind<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + ty::PredicateKind::ForAll(binder) => write!(f, "ForAll({:?})", binder), + ty::PredicateKind::Atom(atom) => write!(f, "{:?}", atom), + } + } +} + +impl fmt::Debug for ty::PredicateAtom<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + ty::PredicateAtom::Trait(ref a, constness) => { + if let hir::Constness::Const = constness { + write!(f, "const ")?; + } + a.fmt(f) + } + ty::PredicateAtom::Subtype(ref pair) => pair.fmt(f), + ty::PredicateAtom::RegionOutlives(ref pair) => pair.fmt(f), + ty::PredicateAtom::TypeOutlives(ref pair) => pair.fmt(f), + ty::PredicateAtom::Projection(ref pair) => pair.fmt(f), + ty::PredicateAtom::WellFormed(data) => write!(f, "WellFormed({:?})", data), + ty::PredicateAtom::ObjectSafe(trait_def_id) => { + write!(f, "ObjectSafe({:?})", trait_def_id) + } + ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind) => { + write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind) + } + ty::PredicateAtom::ConstEvaluatable(def_id, substs) => { + write!(f, "ConstEvaluatable({:?}, {:?})", def_id, substs) + } + ty::PredicateAtom::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2), + } + } +} + +/////////////////////////////////////////////////////////////////////////// +// Atomic structs +// +// For things that don't carry any arena-allocated data (and are +// copy...), just add them to this list. + +CloneTypeFoldableAndLiftImpls! { + (), + bool, + usize, + ::rustc_target::abi::VariantIdx, + u32, + u64, + String, + crate::middle::region::Scope, + ::rustc_ast::FloatTy, + ::rustc_ast::InlineAsmOptions, + ::rustc_ast::InlineAsmTemplatePiece, + ::rustc_ast::NodeId, + ::rustc_span::symbol::Symbol, + ::rustc_hir::def::Res, + ::rustc_hir::def_id::DefId, + ::rustc_hir::def_id::LocalDefId, + ::rustc_hir::HirId, + ::rustc_hir::LlvmInlineAsmInner, + ::rustc_hir::MatchSource, + ::rustc_hir::Mutability, + ::rustc_hir::Unsafety, + ::rustc_target::asm::InlineAsmRegOrRegClass, + ::rustc_target::spec::abi::Abi, + crate::mir::coverage::ExpressionOperandId, + crate::mir::coverage::CounterValueReference, + crate::mir::coverage::InjectedExpressionIndex, + crate::mir::coverage::MappedExpressionIndex, + crate::mir::Local, + crate::mir::Promoted, + crate::traits::Reveal, + crate::ty::adjustment::AutoBorrowMutability, + crate::ty::AdtKind, + // Including `BoundRegion` is a *bit* dubious, but direct + // references to bound region appear in `ty::Error`, and aren't + // really meant to be folded. In general, we can only fold a fully + // general `Region`. + crate::ty::BoundRegion, + crate::ty::AssocItem, + crate::ty::Placeholder<crate::ty::BoundRegion>, + crate::ty::ClosureKind, + crate::ty::FreeRegion, + crate::ty::InferTy, + crate::ty::IntVarValue, + crate::ty::ParamConst, + crate::ty::ParamTy, + crate::ty::adjustment::PointerCast, + crate::ty::RegionVid, + crate::ty::UniverseIndex, + crate::ty::Variance, + ::rustc_span::Span, +} + +/////////////////////////////////////////////////////////////////////////// +// Lift implementations + +// FIXME(eddyb) replace all the uses of `Option::map` with `?`. +impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) { + type Lifted = (A::Lifted, B::Lifted); + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.0).and_then(|a| tcx.lift(&self.1).map(|b| (a, b))) + } +} + +impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) { + type Lifted = (A::Lifted, B::Lifted, C::Lifted); + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.0) + .and_then(|a| tcx.lift(&self.1).and_then(|b| tcx.lift(&self.2).map(|c| (a, b, c)))) + } +} + +impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> { + type Lifted = Option<T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match *self { + Some(ref x) => tcx.lift(x).map(Some), + None => Some(None), + } + } +} + +impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> { + type Lifted = Result<T::Lifted, E::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match *self { + Ok(ref x) => tcx.lift(x).map(Ok), + Err(ref e) => tcx.lift(e).map(Err), + } + } +} + +impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> { + type Lifted = Box<T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&**self).map(Box::new) + } +} + +impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Rc<T> { + type Lifted = Rc<T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&**self).map(Rc::new) + } +} + +impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Arc<T> { + type Lifted = Arc<T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&**self).map(Arc::new) + } +} + +impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for [T] { + type Lifted = Vec<T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + // type annotation needed to inform `projection_must_outlive` + let mut result: Vec<<T as Lift<'tcx>>::Lifted> = Vec::with_capacity(self.len()); + for x in self { + if let Some(value) = tcx.lift(x) { + result.push(value); + } else { + return None; + } + } + Some(result) + } +} + +impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> { + type Lifted = Vec<T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self[..]) + } +} + +impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> { + type Lifted = IndexVec<I, T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + self.iter().map(|e| tcx.lift(e)).collect() + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> { + type Lifted = ty::TraitRef<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> { + type Lifted = ty::ExistentialTraitRef<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> { + type Lifted = ty::ExistentialPredicate<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match self { + ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait), + ty::ExistentialPredicate::Projection(x) => { + tcx.lift(x).map(ty::ExistentialPredicate::Projection) + } + ty::ExistentialPredicate::AutoTrait(def_id) => { + Some(ty::ExistentialPredicate::AutoTrait(*def_id)) + } + } + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> { + type Lifted = ty::TraitPredicate<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> { + tcx.lift(&self.trait_ref).map(|trait_ref| ty::TraitPredicate { trait_ref }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> { + type Lifted = ty::SubtypePredicate<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> { + tcx.lift(&(self.a, self.b)).map(|(a, b)| ty::SubtypePredicate { + a_is_expected: self.a_is_expected, + a, + b, + }) + } +} + +impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> { + type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&(self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b)) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> { + type Lifted = ty::ProjectionTy<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> { + tcx.lift(&self.substs) + .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> { + type Lifted = ty::ProjectionPredicate<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> { + tcx.lift(&(self.projection_ty, self.ty)) + .map(|(projection_ty, ty)| ty::ProjectionPredicate { projection_ty, ty }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> { + type Lifted = ty::ExistentialProjection<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.substs).map(|substs| ty::ExistentialProjection { + substs, + ty: tcx.lift(&self.ty).expect("type must lift when substs do"), + item_def_id: self.item_def_id, + }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> { + type Lifted = ty::PredicateKind<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match self { + ty::PredicateKind::ForAll(binder) => tcx.lift(binder).map(ty::PredicateKind::ForAll), + ty::PredicateKind::Atom(atom) => tcx.lift(atom).map(ty::PredicateKind::Atom), + } + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::PredicateAtom<'a> { + type Lifted = ty::PredicateAtom<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match *self { + ty::PredicateAtom::Trait(ref data, constness) => { + tcx.lift(data).map(|data| ty::PredicateAtom::Trait(data, constness)) + } + ty::PredicateAtom::Subtype(ref data) => tcx.lift(data).map(ty::PredicateAtom::Subtype), + ty::PredicateAtom::RegionOutlives(ref data) => { + tcx.lift(data).map(ty::PredicateAtom::RegionOutlives) + } + ty::PredicateAtom::TypeOutlives(ref data) => { + tcx.lift(data).map(ty::PredicateAtom::TypeOutlives) + } + ty::PredicateAtom::Projection(ref data) => { + tcx.lift(data).map(ty::PredicateAtom::Projection) + } + ty::PredicateAtom::WellFormed(ty) => tcx.lift(&ty).map(ty::PredicateAtom::WellFormed), + ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind) => { + tcx.lift(&closure_substs).map(|closure_substs| { + ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind) + }) + } + ty::PredicateAtom::ObjectSafe(trait_def_id) => { + Some(ty::PredicateAtom::ObjectSafe(trait_def_id)) + } + ty::PredicateAtom::ConstEvaluatable(def_id, substs) => { + tcx.lift(&substs).map(|substs| ty::PredicateAtom::ConstEvaluatable(def_id, substs)) + } + ty::PredicateAtom::ConstEquate(c1, c2) => { + tcx.lift(&(c1, c2)).map(|(c1, c2)| ty::PredicateAtom::ConstEquate(c1, c2)) + } + } + } +} + +impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<T> { + type Lifted = ty::Binder<T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(self.as_ref().skip_binder()).map(ty::Binder::bind) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> { + type Lifted = ty::ParamEnv<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.caller_bounds()) + .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal(), self.def_id)) + } +} + +impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> { + type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.param_env).and_then(|param_env| { + tcx.lift(&self.value).map(|value| ty::ParamEnvAnd { param_env, value }) + }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> { + type Lifted = ty::ClosureSubsts<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.substs).map(|substs| ty::ClosureSubsts { substs }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> { + type Lifted = ty::GeneratorSubsts<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.substs).map(|substs| ty::GeneratorSubsts { substs }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> { + type Lifted = ty::adjustment::Adjustment<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.kind).and_then(|kind| { + tcx.lift(&self.target).map(|target| ty::adjustment::Adjustment { kind, target }) + }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> { + type Lifted = ty::adjustment::Adjust<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match *self { + ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny), + ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)), + ty::adjustment::Adjust::Deref(ref overloaded) => { + tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref) + } + ty::adjustment::Adjust::Borrow(ref autoref) => { + tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow) + } + } + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> { + type Lifted = ty::adjustment::OverloadedDeref<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.region) + .map(|region| ty::adjustment::OverloadedDeref { region, mutbl: self.mutbl }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> { + type Lifted = ty::adjustment::AutoBorrow<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match *self { + ty::adjustment::AutoBorrow::Ref(r, m) => { + tcx.lift(&r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m)) + } + ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)), + } + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> { + type Lifted = ty::GenSig<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&(self.resume_ty, self.yield_ty, self.return_ty)) + .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> { + type Lifted = ty::FnSig<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.inputs_and_output).map(|x| ty::FnSig { + inputs_and_output: x, + c_variadic: self.c_variadic, + unsafety: self.unsafety, + abi: self.abi, + }) + } +} + +impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> { + type Lifted = ty::error::ExpectedFound<T::Lifted>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + tcx.lift(&self.expected).and_then(|expected| { + tcx.lift(&self.found).map(|found| ty::error::ExpectedFound { expected, found }) + }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> { + type Lifted = ty::error::TypeError<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + use crate::ty::error::TypeError::*; + + Some(match *self { + Mismatch => Mismatch, + UnsafetyMismatch(x) => UnsafetyMismatch(x), + AbiMismatch(x) => AbiMismatch(x), + Mutability => Mutability, + TupleSize(x) => TupleSize(x), + FixedArraySize(x) => FixedArraySize(x), + ArgCount => ArgCount, + RegionsDoesNotOutlive(a, b) => { + return tcx.lift(&(a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b)); + } + RegionsInsufficientlyPolymorphic(a, b) => { + return tcx.lift(&b).map(|b| RegionsInsufficientlyPolymorphic(a, b)); + } + RegionsOverlyPolymorphic(a, b) => { + return tcx.lift(&b).map(|b| RegionsOverlyPolymorphic(a, b)); + } + RegionsPlaceholderMismatch => RegionsPlaceholderMismatch, + IntMismatch(x) => IntMismatch(x), + FloatMismatch(x) => FloatMismatch(x), + Traits(x) => Traits(x), + VariadicMismatch(x) => VariadicMismatch(x), + CyclicTy(t) => return tcx.lift(&t).map(|t| CyclicTy(t)), + ProjectionMismatched(x) => ProjectionMismatched(x), + Sorts(ref x) => return tcx.lift(x).map(Sorts), + ExistentialMismatch(ref x) => return tcx.lift(x).map(ExistentialMismatch), + ConstMismatch(ref x) => return tcx.lift(x).map(ConstMismatch), + IntrinsicCast => IntrinsicCast, + TargetFeatureCast(ref x) => TargetFeatureCast(*x), + ObjectUnsafeCoercion(ref x) => return tcx.lift(x).map(ObjectUnsafeCoercion), + }) + } +} + +impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> { + type Lifted = ty::InstanceDef<'tcx>; + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match *self { + ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)), + ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)), + ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)), + ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)), + ty::InstanceDef::FnPtrShim(def_id, ref ty) => { + Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?)) + } + ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)), + ty::InstanceDef::ClosureOnceShim { call_once } => { + Some(ty::InstanceDef::ClosureOnceShim { call_once }) + } + ty::InstanceDef::DropGlue(def_id, ref ty) => { + Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?)) + } + ty::InstanceDef::CloneShim(def_id, ref ty) => { + Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?)) + } + } + } +} + +/////////////////////////////////////////////////////////////////////////// +// TypeFoldable implementations. +// +// Ideally, each type should invoke `folder.fold_foo(self)` and +// nothing else. In some cases, though, we haven't gotten around to +// adding methods on the `folder` yet, and thus the folding is +// hard-coded here. This is less-flexible, because folders cannot +// override the behavior, but there are a lot of random types and one +// can easily refactor the folding into the TypeFolder trait as +// needed. + +/// AdtDefs are basically the same as a DefId. +impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self { + *self + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool { + false + } +} + +impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> (T, U) { + (self.0.fold_with(folder), self.1.fold_with(folder)) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.0.visit_with(visitor) || self.1.visit_with(visitor) + } +} + +impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx> + for (A, B, C) +{ + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> (A, B, C) { + (self.0.fold_with(folder), self.1.fold_with(folder), self.2.fold_with(folder)) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.0.visit_with(visitor) || self.1.visit_with(visitor) || self.2.visit_with(visitor) + } +} + +EnumTypeFoldableImpl! { + impl<'tcx, T> TypeFoldable<'tcx> for Option<T> { + (Some)(a), + (None), + } where T: TypeFoldable<'tcx> +} + +EnumTypeFoldableImpl! { + impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> { + (Ok)(a), + (Err)(a), + } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>, +} + +impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + Rc::new((**self).fold_with(folder)) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + (**self).visit_with(visitor) + } +} + +impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + Arc::new((**self).fold_with(folder)) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + (**self).visit_with(visitor) + } +} + +impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + let content: T = (**self).fold_with(folder); + box content + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + (**self).visit_with(visitor) + } +} + +impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + self.iter().map(|t| t.fold_with(folder)).collect() + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|t| t.visit_with(visitor)) + } +} + +impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + self.iter().map(|t| t.fold_with(folder)).collect::<Vec<_>>().into_boxed_slice() + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|t| t.visit_with(visitor)) + } +} + +impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<T> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + self.map_bound_ref(|ty| ty.fold_with(folder)) + } + + fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + folder.fold_binder(self) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.as_ref().skip_binder().visit_with(visitor) + } + + fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + visitor.visit_binder(self) + } +} + +impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::ExistentialPredicate<'tcx>> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + fold_list(*self, folder, |tcx, v| tcx.intern_existential_predicates(v)) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|p| p.visit_with(visitor)) + } +} + +impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + fold_list(*self, folder, |tcx, v| tcx.intern_type_list(v)) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|t| t.visit_with(visitor)) + } +} + +impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + fold_list(*self, folder, |tcx, v| tcx.intern_projs(v)) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|t| t.visit_with(visitor)) + } +} + +impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + use crate::ty::InstanceDef::*; + Self { + substs: self.substs.fold_with(folder), + def: match self.def { + Item(def) => Item(def.fold_with(folder)), + VtableShim(did) => VtableShim(did.fold_with(folder)), + ReifyShim(did) => ReifyShim(did.fold_with(folder)), + Intrinsic(did) => Intrinsic(did.fold_with(folder)), + FnPtrShim(did, ty) => FnPtrShim(did.fold_with(folder), ty.fold_with(folder)), + Virtual(did, i) => Virtual(did.fold_with(folder), i), + ClosureOnceShim { call_once } => { + ClosureOnceShim { call_once: call_once.fold_with(folder) } + } + DropGlue(did, ty) => DropGlue(did.fold_with(folder), ty.fold_with(folder)), + CloneShim(did, ty) => CloneShim(did.fold_with(folder), ty.fold_with(folder)), + }, + } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + use crate::ty::InstanceDef::*; + self.substs.visit_with(visitor) + || match self.def { + Item(def) => def.visit_with(visitor), + VtableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => { + did.visit_with(visitor) + } + FnPtrShim(did, ty) | CloneShim(did, ty) => { + did.visit_with(visitor) || ty.visit_with(visitor) + } + DropGlue(did, ty) => did.visit_with(visitor) || ty.visit_with(visitor), + ClosureOnceShim { call_once } => call_once.visit_with(visitor), + } + } +} + +impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + Self { instance: self.instance.fold_with(folder), promoted: self.promoted } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.instance.visit_with(visitor) + } +} + +impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + let kind = match self.kind { + ty::RawPtr(tm) => ty::RawPtr(tm.fold_with(folder)), + ty::Array(typ, sz) => ty::Array(typ.fold_with(folder), sz.fold_with(folder)), + ty::Slice(typ) => ty::Slice(typ.fold_with(folder)), + ty::Adt(tid, substs) => ty::Adt(tid, substs.fold_with(folder)), + ty::Dynamic(ref trait_ty, ref region) => { + ty::Dynamic(trait_ty.fold_with(folder), region.fold_with(folder)) + } + ty::Tuple(ts) => ty::Tuple(ts.fold_with(folder)), + ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.fold_with(folder)), + ty::FnPtr(f) => ty::FnPtr(f.fold_with(folder)), + ty::Ref(ref r, ty, mutbl) => ty::Ref(r.fold_with(folder), ty.fold_with(folder), mutbl), + ty::Generator(did, substs, movability) => { + ty::Generator(did, substs.fold_with(folder), movability) + } + ty::GeneratorWitness(types) => ty::GeneratorWitness(types.fold_with(folder)), + ty::Closure(did, substs) => ty::Closure(did, substs.fold_with(folder)), + ty::Projection(ref data) => ty::Projection(data.fold_with(folder)), + ty::Opaque(did, substs) => ty::Opaque(did, substs.fold_with(folder)), + + ty::Bool + | ty::Char + | ty::Str + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Error(_) + | ty::Infer(_) + | ty::Param(..) + | ty::Bound(..) + | ty::Placeholder(..) + | ty::Never + | ty::Foreign(..) => return self, + }; + + if self.kind == kind { self } else { folder.tcx().mk_ty(kind) } + } + + fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + folder.fold_ty(*self) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + match self.kind { + ty::RawPtr(ref tm) => tm.visit_with(visitor), + ty::Array(typ, sz) => typ.visit_with(visitor) || sz.visit_with(visitor), + ty::Slice(typ) => typ.visit_with(visitor), + ty::Adt(_, substs) => substs.visit_with(visitor), + ty::Dynamic(ref trait_ty, ref reg) => { + trait_ty.visit_with(visitor) || reg.visit_with(visitor) + } + ty::Tuple(ts) => ts.visit_with(visitor), + ty::FnDef(_, substs) => substs.visit_with(visitor), + ty::FnPtr(ref f) => f.visit_with(visitor), + ty::Ref(r, ty, _) => r.visit_with(visitor) || ty.visit_with(visitor), + ty::Generator(_did, ref substs, _) => substs.visit_with(visitor), + ty::GeneratorWitness(ref types) => types.visit_with(visitor), + ty::Closure(_did, ref substs) => substs.visit_with(visitor), + ty::Projection(ref data) => data.visit_with(visitor), + ty::Opaque(_, ref substs) => substs.visit_with(visitor), + + ty::Bool + | ty::Char + | ty::Str + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Error(_) + | ty::Infer(_) + | ty::Bound(..) + | ty::Placeholder(..) + | ty::Param(..) + | ty::Never + | ty::Foreign(..) => false, + } + } + + fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + visitor.visit_ty(self) + } +} + +impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self { + *self + } + + fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + folder.fold_region(*self) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool { + false + } + + fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + visitor.visit_region(*self) + } +} + +impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + let new = ty::PredicateKind::super_fold_with(&self.inner.kind, folder); + folder.tcx().reuse_or_mk_predicate(*self, new) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + ty::PredicateKind::super_visit_with(&self.inner.kind, visitor) + } + + fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + visitor.visit_predicate(*self) + } + + fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool { + self.inner.outer_exclusive_binder > binder + } + + fn has_type_flags(&self, flags: ty::TypeFlags) -> bool { + self.inner.flags.intersects(flags) + } +} + +pub(super) trait PredicateVisitor<'tcx>: TypeVisitor<'tcx> { + fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> bool; +} + +impl<T: TypeVisitor<'tcx>> PredicateVisitor<'tcx> for T { + default fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> bool { + predicate.super_visit_with(self) + } +} + +impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + fold_list(*self, folder, |tcx, v| tcx.intern_predicates(v)) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|p| p.visit_with(visitor)) + } +} + +impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + self.iter().map(|x| x.fold_with(folder)).collect() + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|t| t.visit_with(visitor)) + } +} + +impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + let ty = self.ty.fold_with(folder); + let val = self.val.fold_with(folder); + if ty != self.ty || val != self.val { + folder.tcx().mk_const(ty::Const { ty, val }) + } else { + *self + } + } + + fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + folder.fold_const(*self) + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.ty.visit_with(visitor) || self.val.visit_with(visitor) + } + + fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + visitor.visit_const(self) + } +} + +impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + match *self { + ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.fold_with(folder)), + ty::ConstKind::Param(p) => ty::ConstKind::Param(p.fold_with(folder)), + ty::ConstKind::Unevaluated(did, substs, promoted) => { + ty::ConstKind::Unevaluated(did, substs.fold_with(folder), promoted) + } + ty::ConstKind::Value(_) + | ty::ConstKind::Bound(..) + | ty::ConstKind::Placeholder(..) + | ty::ConstKind::Error(_) => *self, + } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + match *self { + ty::ConstKind::Infer(ic) => ic.visit_with(visitor), + ty::ConstKind::Param(p) => p.visit_with(visitor), + ty::ConstKind::Unevaluated(_, substs, _) => substs.visit_with(visitor), + ty::ConstKind::Value(_) + | ty::ConstKind::Bound(..) + | ty::ConstKind::Placeholder(_) + | ty::ConstKind::Error(_) => false, + } + } +} + +impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self { + *self + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool { + false + } +} + +// Does the equivalent of +// ``` +// let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>(); +// folder.tcx().intern_*(&v) +// ``` +fn fold_list<'tcx, F, T>( + list: &'tcx ty::List<T>, + folder: &mut F, + intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> &'tcx ty::List<T>, +) -> &'tcx ty::List<T> +where + F: TypeFolder<'tcx>, + T: TypeFoldable<'tcx> + PartialEq + Copy, +{ + let mut iter = list.iter(); + // Look for the first element that changed + if let Some((i, new_t)) = iter.by_ref().enumerate().find_map(|(i, t)| { + let new_t = t.fold_with(folder); + if new_t == t { None } else { Some((i, new_t)) } + }) { + // An element changed, prepare to intern the resulting list + let mut new_list = SmallVec::<[_; 8]>::with_capacity(list.len()); + new_list.extend_from_slice(&list[..i]); + new_list.push(new_t); + new_list.extend(iter.map(|t| t.fold_with(folder))); + intern(folder.tcx(), &new_list) + } else { + list + } +} diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs new file mode 100644 index 00000000000..c1f354c7a15 --- /dev/null +++ b/compiler/rustc_middle/src/ty/sty.rs @@ -0,0 +1,2288 @@ +//! This module contains `TyKind` and its major components. + +#![allow(rustc::usage_of_ty_tykind)] + +use self::InferTy::*; +use self::TyKind::*; + +use crate::infer::canonical::Canonical; +use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef}; +use crate::ty::{ + self, AdtDef, DefIdTree, Discr, Ty, TyCtxt, TypeFlags, TypeFoldable, WithConstness, +}; +use crate::ty::{DelaySpanBugEmitted, List, ParamEnv, TyS}; +use polonius_engine::Atom; +use rustc_ast as ast; +use rustc_data_structures::captures::Captures; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_index::vec::Idx; +use rustc_macros::HashStable; +use rustc_span::symbol::{kw, Ident, Symbol}; +use rustc_target::abi::VariantIdx; +use rustc_target::spec::abi; +use std::borrow::Cow; +use std::cmp::Ordering; +use std::marker::PhantomData; +use std::ops::Range; +use ty::util::IntTypeExt; + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable, Lift)] +pub struct TypeAndMut<'tcx> { + pub ty: Ty<'tcx>, + pub mutbl: hir::Mutability, +} + +#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)] +#[derive(HashStable)] +/// A "free" region `fr` can be interpreted as "some region +/// at least as big as the scope `fr.scope`". +pub struct FreeRegion { + pub scope: DefId, + pub bound_region: BoundRegion, +} + +#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)] +#[derive(HashStable)] +pub enum BoundRegion { + /// An anonymous region parameter for a given fn (&T) + BrAnon(u32), + + /// Named region parameters for functions (a in &'a T) + /// + /// The `DefId` is needed to distinguish free regions in + /// the event of shadowing. + BrNamed(DefId, Symbol), + + /// Anonymous region for the implicit env pointer parameter + /// to a closure + BrEnv, +} + +impl BoundRegion { + pub fn is_named(&self) -> bool { + match *self { + BoundRegion::BrNamed(_, name) => name != kw::UnderscoreLifetime, + _ => false, + } + } + + /// When canonicalizing, we replace unbound inference variables and free + /// regions with anonymous late bound regions. This method asserts that + /// we have an anonymous late bound region, which hence may refer to + /// a canonical variable. + pub fn assert_bound_var(&self) -> BoundVar { + match *self { + BoundRegion::BrAnon(var) => BoundVar::from_u32(var), + _ => bug!("bound region is not anonymous"), + } + } +} + +/// N.B., if you change this, you'll probably want to change the corresponding +/// AST structure in `librustc_ast/ast.rs` as well. +#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable, Debug)] +#[derive(HashStable)] +#[rustc_diagnostic_item = "TyKind"] +pub enum TyKind<'tcx> { + /// The primitive boolean type. Written as `bool`. + Bool, + + /// The primitive character type; holds a Unicode scalar value + /// (a non-surrogate code point). Written as `char`. + Char, + + /// A primitive signed integer type. For example, `i32`. + Int(ast::IntTy), + + /// A primitive unsigned integer type. For example, `u32`. + Uint(ast::UintTy), + + /// A primitive floating-point type. For example, `f64`. + Float(ast::FloatTy), + + /// Structures, enumerations and unions. + /// + /// InternalSubsts here, possibly against intuition, *may* contain `Param`s. + /// That is, even after substitution it is possible that there are type + /// variables. This happens when the `Adt` corresponds to an ADT + /// definition and not a concrete use of it. + Adt(&'tcx AdtDef, SubstsRef<'tcx>), + + /// An unsized FFI type that is opaque to Rust. Written as `extern type T`. + Foreign(DefId), + + /// The pointee of a string slice. Written as `str`. + Str, + + /// An array with the given length. Written as `[T; n]`. + Array(Ty<'tcx>, &'tcx ty::Const<'tcx>), + + /// The pointee of an array slice. Written as `[T]`. + Slice(Ty<'tcx>), + + /// A raw pointer. Written as `*mut T` or `*const T` + RawPtr(TypeAndMut<'tcx>), + + /// A reference; a pointer with an associated lifetime. Written as + /// `&'a mut T` or `&'a T`. + Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability), + + /// The anonymous type of a function declaration/definition. Each + /// function has a unique type, which is output (for a function + /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`. + /// + /// For example the type of `bar` here: + /// + /// ```rust + /// fn foo() -> i32 { 1 } + /// let bar = foo; // bar: fn() -> i32 {foo} + /// ``` + FnDef(DefId, SubstsRef<'tcx>), + + /// A pointer to a function. Written as `fn() -> i32`. + /// + /// For example the type of `bar` here: + /// + /// ```rust + /// fn foo() -> i32 { 1 } + /// let bar: fn() -> i32 = foo; + /// ``` + FnPtr(PolyFnSig<'tcx>), + + /// A trait, defined with `trait`. + Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>), + + /// The anonymous type of a closure. Used to represent the type of + /// `|a| a`. + Closure(DefId, SubstsRef<'tcx>), + + /// The anonymous type of a generator. Used to represent the type of + /// `|a| yield a`. + Generator(DefId, SubstsRef<'tcx>, hir::Movability), + + /// A type representin the types stored inside a generator. + /// This should only appear in GeneratorInteriors. + GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>), + + /// The never type `!` + Never, + + /// A tuple type. For example, `(i32, bool)`. + /// Use `TyS::tuple_fields` to iterate over the field types. + Tuple(SubstsRef<'tcx>), + + /// The projection of an associated type. For example, + /// `<T as Trait<..>>::N`. + Projection(ProjectionTy<'tcx>), + + /// Opaque (`impl Trait`) type found in a return type. + /// The `DefId` comes either from + /// * the `impl Trait` ast::Ty node, + /// * or the `type Foo = impl Trait` declaration + /// The substitutions are for the generics of the function in question. + /// After typeck, the concrete type can be found in the `types` map. + Opaque(DefId, SubstsRef<'tcx>), + + /// A type parameter; for example, `T` in `fn f<T>(x: T) {}`. + Param(ParamTy), + + /// Bound type variable, used only when preparing a trait query. + Bound(ty::DebruijnIndex, BoundTy), + + /// A placeholder type - universally quantified higher-ranked type. + Placeholder(ty::PlaceholderType), + + /// A type variable used during type checking. + Infer(InferTy), + + /// A placeholder for a type which could not be computed; this is + /// propagated to avoid useless error messages. + Error(DelaySpanBugEmitted), +} + +impl TyKind<'tcx> { + #[inline] + pub fn is_primitive(&self) -> bool { + match self { + Bool | Char | Int(_) | Uint(_) | Float(_) => true, + _ => false, + } + } +} + +// `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger. +#[cfg(target_arch = "x86_64")] +static_assert_size!(TyKind<'_>, 24); + +/// A closure can be modeled as a struct that looks like: +/// +/// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U); +/// +/// where: +/// +/// - 'l0...'li and T0...Tj are the generic parameters +/// in scope on the function that defined the closure, +/// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This +/// is rather hackily encoded via a scalar type. See +/// `TyS::to_opt_closure_kind` for details. +/// - CS represents the *closure signature*, representing as a `fn()` +/// type. For example, `fn(u32, u32) -> u32` would mean that the closure +/// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait +/// specified above. +/// - U is a type parameter representing the types of its upvars, tupled up +/// (borrowed, if appropriate; that is, if an U field represents a by-ref upvar, +/// and the up-var has the type `Foo`, then that field of U will be `&Foo`). +/// +/// So, for example, given this function: +/// +/// fn foo<'a, T>(data: &'a mut T) { +/// do(|| data.count += 1) +/// } +/// +/// the type of the closure would be something like: +/// +/// struct Closure<'a, T, U>(...U); +/// +/// Note that the type of the upvar is not specified in the struct. +/// You may wonder how the impl would then be able to use the upvar, +/// if it doesn't know it's type? The answer is that the impl is +/// (conceptually) not fully generic over Closure but rather tied to +/// instances with the expected upvar types: +/// +/// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> { +/// ... +/// } +/// +/// You can see that the *impl* fully specified the type of the upvar +/// and thus knows full well that `data` has type `&'b mut &'a mut T`. +/// (Here, I am assuming that `data` is mut-borrowed.) +/// +/// Now, the last question you may ask is: Why include the upvar types +/// in an extra type parameter? The reason for this design is that the +/// upvar types can reference lifetimes that are internal to the +/// creating function. In my example above, for example, the lifetime +/// `'b` represents the scope of the closure itself; this is some +/// subset of `foo`, probably just the scope of the call to the to +/// `do()`. If we just had the lifetime/type parameters from the +/// enclosing function, we couldn't name this lifetime `'b`. Note that +/// there can also be lifetimes in the types of the upvars themselves, +/// if one of them happens to be a reference to something that the +/// creating fn owns. +/// +/// OK, you say, so why not create a more minimal set of parameters +/// that just includes the extra lifetime parameters? The answer is +/// primarily that it would be hard --- we don't know at the time when +/// we create the closure type what the full types of the upvars are, +/// nor do we know which are borrowed and which are not. In this +/// design, we can just supply a fresh type parameter and figure that +/// out later. +/// +/// All right, you say, but why include the type parameters from the +/// original function then? The answer is that codegen may need them +/// when monomorphizing, and they may not appear in the upvars. A +/// closure could capture no variables but still make use of some +/// in-scope type parameter with a bound (e.g., if our example above +/// had an extra `U: Default`, and the closure called `U::default()`). +/// +/// There is another reason. This design (implicitly) prohibits +/// closures from capturing themselves (except via a trait +/// object). This simplifies closure inference considerably, since it +/// means that when we infer the kind of a closure or its upvars, we +/// don't have to handle cycles where the decisions we make for +/// closure C wind up influencing the decisions we ought to make for +/// closure C (which would then require fixed point iteration to +/// handle). Plus it fixes an ICE. :P +/// +/// ## Generators +/// +/// Generators are handled similarly in `GeneratorSubsts`. The set of +/// type parameters is similar, but `CK` and `CS` are replaced by the +/// following type parameters: +/// +/// * `GS`: The generator's "resume type", which is the type of the +/// argument passed to `resume`, and the type of `yield` expressions +/// inside the generator. +/// * `GY`: The "yield type", which is the type of values passed to +/// `yield` inside the generator. +/// * `GR`: The "return type", which is the type of value returned upon +/// completion of the generator. +/// * `GW`: The "generator witness". +#[derive(Copy, Clone, Debug, TypeFoldable)] +pub struct ClosureSubsts<'tcx> { + /// Lifetime and type parameters from the enclosing function, + /// concatenated with a tuple containing the types of the upvars. + /// + /// These are separated out because codegen wants to pass them around + /// when monomorphizing. + pub substs: SubstsRef<'tcx>, +} + +/// Struct returned by `split()`. +pub struct ClosureSubstsParts<'tcx, T> { + pub parent_substs: &'tcx [GenericArg<'tcx>], + pub closure_kind_ty: T, + pub closure_sig_as_fn_ptr_ty: T, + pub tupled_upvars_ty: T, +} + +impl<'tcx> ClosureSubsts<'tcx> { + /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs` + /// for the closure parent, alongside additional closure-specific components. + pub fn new( + tcx: TyCtxt<'tcx>, + parts: ClosureSubstsParts<'tcx, Ty<'tcx>>, + ) -> ClosureSubsts<'tcx> { + ClosureSubsts { + substs: tcx.mk_substs( + parts.parent_substs.iter().copied().chain( + [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty] + .iter() + .map(|&ty| ty.into()), + ), + ), + } + } + + /// Divides the closure substs into their respective components. + /// The ordering assumed here must match that used by `ClosureSubsts::new` above. + fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> { + match self.substs[..] { + [ref parent_substs @ .., closure_kind_ty, closure_sig_as_fn_ptr_ty, tupled_upvars_ty] => { + ClosureSubstsParts { + parent_substs, + closure_kind_ty, + closure_sig_as_fn_ptr_ty, + tupled_upvars_ty, + } + } + _ => bug!("closure substs missing synthetics"), + } + } + + /// Returns `true` only if enough of the synthetic types are known to + /// allow using all of the methods on `ClosureSubsts` without panicking. + /// + /// Used primarily by `ty::print::pretty` to be able to handle closure + /// types that haven't had their synthetic types substituted in. + pub fn is_valid(self) -> bool { + self.substs.len() >= 3 && matches!(self.split().tupled_upvars_ty.expect_ty().kind, Tuple(_)) + } + + /// Returns the substitutions of the closure's parent. + pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] { + self.split().parent_substs + } + + #[inline] + pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { + self.tupled_upvars_ty().tuple_fields() + } + + /// Returns the tuple type representing the upvars for this closure. + #[inline] + pub fn tupled_upvars_ty(self) -> Ty<'tcx> { + self.split().tupled_upvars_ty.expect_ty() + } + + /// Returns the closure kind for this closure; may return a type + /// variable during inference. To get the closure kind during + /// inference, use `infcx.closure_kind(substs)`. + pub fn kind_ty(self) -> Ty<'tcx> { + self.split().closure_kind_ty.expect_ty() + } + + /// Returns the `fn` pointer type representing the closure signature for this + /// closure. + // FIXME(eddyb) this should be unnecessary, as the shallowly resolved + // type is known at the time of the creation of `ClosureSubsts`, + // see `rustc_typeck::check::closure`. + pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> { + self.split().closure_sig_as_fn_ptr_ty.expect_ty() + } + + /// Returns the closure kind for this closure; only usable outside + /// of an inference context, because in that context we know that + /// there are no type variables. + /// + /// If you have an inference context, use `infcx.closure_kind()`. + pub fn kind(self) -> ty::ClosureKind { + self.kind_ty().to_opt_closure_kind().unwrap() + } + + /// Extracts the signature from the closure. + pub fn sig(self) -> ty::PolyFnSig<'tcx> { + let ty = self.sig_as_fn_ptr_ty(); + match ty.kind { + ty::FnPtr(sig) => sig, + _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind), + } + } +} + +/// Similar to `ClosureSubsts`; see the above documentation for more. +#[derive(Copy, Clone, Debug, TypeFoldable)] +pub struct GeneratorSubsts<'tcx> { + pub substs: SubstsRef<'tcx>, +} + +pub struct GeneratorSubstsParts<'tcx, T> { + pub parent_substs: &'tcx [GenericArg<'tcx>], + pub resume_ty: T, + pub yield_ty: T, + pub return_ty: T, + pub witness: T, + pub tupled_upvars_ty: T, +} + +impl<'tcx> GeneratorSubsts<'tcx> { + /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs` + /// for the generator parent, alongside additional generator-specific components. + pub fn new( + tcx: TyCtxt<'tcx>, + parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>, + ) -> GeneratorSubsts<'tcx> { + GeneratorSubsts { + substs: tcx.mk_substs( + parts.parent_substs.iter().copied().chain( + [ + parts.resume_ty, + parts.yield_ty, + parts.return_ty, + parts.witness, + parts.tupled_upvars_ty, + ] + .iter() + .map(|&ty| ty.into()), + ), + ), + } + } + + /// Divides the generator substs into their respective components. + /// The ordering assumed here must match that used by `GeneratorSubsts::new` above. + fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> { + match self.substs[..] { + [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => { + GeneratorSubstsParts { + parent_substs, + resume_ty, + yield_ty, + return_ty, + witness, + tupled_upvars_ty, + } + } + _ => bug!("generator substs missing synthetics"), + } + } + + /// Returns `true` only if enough of the synthetic types are known to + /// allow using all of the methods on `GeneratorSubsts` without panicking. + /// + /// Used primarily by `ty::print::pretty` to be able to handle generator + /// types that haven't had their synthetic types substituted in. + pub fn is_valid(self) -> bool { + self.substs.len() >= 5 && matches!(self.split().tupled_upvars_ty.expect_ty().kind, Tuple(_)) + } + + /// Returns the substitutions of the generator's parent. + pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] { + self.split().parent_substs + } + + /// This describes the types that can be contained in a generator. + /// It will be a type variable initially and unified in the last stages of typeck of a body. + /// It contains a tuple of all the types that could end up on a generator frame. + /// The state transformation MIR pass may only produce layouts which mention types + /// in this tuple. Upvars are not counted here. + pub fn witness(self) -> Ty<'tcx> { + self.split().witness.expect_ty() + } + + #[inline] + pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { + self.tupled_upvars_ty().tuple_fields() + } + + /// Returns the tuple type representing the upvars for this generator. + #[inline] + pub fn tupled_upvars_ty(self) -> Ty<'tcx> { + self.split().tupled_upvars_ty.expect_ty() + } + + /// Returns the type representing the resume type of the generator. + pub fn resume_ty(self) -> Ty<'tcx> { + self.split().resume_ty.expect_ty() + } + + /// Returns the type representing the yield type of the generator. + pub fn yield_ty(self) -> Ty<'tcx> { + self.split().yield_ty.expect_ty() + } + + /// Returns the type representing the return type of the generator. + pub fn return_ty(self) -> Ty<'tcx> { + self.split().return_ty.expect_ty() + } + + /// Returns the "generator signature", which consists of its yield + /// and return types. + /// + /// N.B., some bits of the code prefers to see this wrapped in a + /// binder, but it never contains bound regions. Probably this + /// function should be removed. + pub fn poly_sig(self) -> PolyGenSig<'tcx> { + ty::Binder::dummy(self.sig()) + } + + /// Returns the "generator signature", which consists of its resume, yield + /// and return types. + pub fn sig(self) -> GenSig<'tcx> { + ty::GenSig { + resume_ty: self.resume_ty(), + yield_ty: self.yield_ty(), + return_ty: self.return_ty(), + } + } +} + +impl<'tcx> GeneratorSubsts<'tcx> { + /// Generator has not been resumed yet. + pub const UNRESUMED: usize = 0; + /// Generator has returned or is completed. + pub const RETURNED: usize = 1; + /// Generator has been poisoned. + pub const POISONED: usize = 2; + + const UNRESUMED_NAME: &'static str = "Unresumed"; + const RETURNED_NAME: &'static str = "Returned"; + const POISONED_NAME: &'static str = "Panicked"; + + /// The valid variant indices of this generator. + #[inline] + pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> { + // FIXME requires optimized MIR + let num_variants = tcx.generator_layout(def_id).variant_fields.len(); + VariantIdx::new(0)..VariantIdx::new(num_variants) + } + + /// The discriminant for the given variant. Panics if the `variant_index` is + /// out of range. + #[inline] + pub fn discriminant_for_variant( + &self, + def_id: DefId, + tcx: TyCtxt<'tcx>, + variant_index: VariantIdx, + ) -> Discr<'tcx> { + // Generators don't support explicit discriminant values, so they are + // the same as the variant index. + assert!(self.variant_range(def_id, tcx).contains(&variant_index)); + Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) } + } + + /// The set of all discriminants for the generator, enumerated with their + /// variant indices. + #[inline] + pub fn discriminants( + self, + def_id: DefId, + tcx: TyCtxt<'tcx>, + ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> { + self.variant_range(def_id, tcx).map(move |index| { + (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) }) + }) + } + + /// Calls `f` with a reference to the name of the enumerator for the given + /// variant `v`. + pub fn variant_name(v: VariantIdx) -> Cow<'static, str> { + match v.as_usize() { + Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME), + Self::RETURNED => Cow::from(Self::RETURNED_NAME), + Self::POISONED => Cow::from(Self::POISONED_NAME), + _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)), + } + } + + /// The type of the state discriminant used in the generator type. + #[inline] + pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + tcx.types.u32 + } + + /// This returns the types of the MIR locals which had to be stored across suspension points. + /// It is calculated in rustc_mir::transform::generator::StateTransform. + /// All the types here must be in the tuple in GeneratorInterior. + /// + /// The locals are grouped by their variant number. Note that some locals may + /// be repeated in multiple variants. + #[inline] + pub fn state_tys( + self, + def_id: DefId, + tcx: TyCtxt<'tcx>, + ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> { + let layout = tcx.generator_layout(def_id); + layout.variant_fields.iter().map(move |variant| { + variant.iter().map(move |field| layout.field_tys[*field].subst(tcx, self.substs)) + }) + } + + /// This is the types of the fields of a generator which are not stored in a + /// variant. + #[inline] + pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> { + self.upvar_tys() + } +} + +#[derive(Debug, Copy, Clone)] +pub enum UpvarSubsts<'tcx> { + Closure(SubstsRef<'tcx>), + Generator(SubstsRef<'tcx>), +} + +impl<'tcx> UpvarSubsts<'tcx> { + #[inline] + pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { + let tupled_upvars_ty = match self { + UpvarSubsts::Closure(substs) => substs.as_closure().split().tupled_upvars_ty, + UpvarSubsts::Generator(substs) => substs.as_generator().split().tupled_upvars_ty, + }; + tupled_upvars_ty.expect_ty().tuple_fields() + } +} + +#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub enum ExistentialPredicate<'tcx> { + /// E.g., `Iterator`. + Trait(ExistentialTraitRef<'tcx>), + /// E.g., `Iterator::Item = T`. + Projection(ExistentialProjection<'tcx>), + /// E.g., `Send`. + AutoTrait(DefId), +} + +impl<'tcx> ExistentialPredicate<'tcx> { + /// Compares via an ordering that will not change if modules are reordered or other changes are + /// made to the tree. In particular, this ordering is preserved across incremental compilations. + pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering { + use self::ExistentialPredicate::*; + match (*self, *other) { + (Trait(_), Trait(_)) => Ordering::Equal, + (Projection(ref a), Projection(ref b)) => { + tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)) + } + (AutoTrait(ref a), AutoTrait(ref b)) => { + tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash) + } + (Trait(_), _) => Ordering::Less, + (Projection(_), Trait(_)) => Ordering::Greater, + (Projection(_), _) => Ordering::Less, + (AutoTrait(_), _) => Ordering::Greater, + } + } +} + +impl<'tcx> Binder<ExistentialPredicate<'tcx>> { + pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> { + use crate::ty::ToPredicate; + match self.skip_binder() { + ExistentialPredicate::Trait(tr) => { + Binder(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx) + } + ExistentialPredicate::Projection(p) => { + Binder(p.with_self_ty(tcx, self_ty)).to_predicate(tcx) + } + ExistentialPredicate::AutoTrait(did) => { + let trait_ref = + Binder(ty::TraitRef { def_id: did, substs: tcx.mk_substs_trait(self_ty, &[]) }); + trait_ref.without_const().to_predicate(tcx) + } + } + } +} + +impl<'tcx> List<ExistentialPredicate<'tcx>> { + /// Returns the "principal `DefId`" of this set of existential predicates. + /// + /// A Rust trait object type consists (in addition to a lifetime bound) + /// of a set of trait bounds, which are separated into any number + /// of auto-trait bounds, and at most one non-auto-trait bound. The + /// non-auto-trait bound is called the "principal" of the trait + /// object. + /// + /// Only the principal can have methods or type parameters (because + /// auto traits can have neither of them). This is important, because + /// it means the auto traits can be treated as an unordered set (methods + /// would force an order for the vtable, while relating traits with + /// type parameters without knowing the order to relate them in is + /// a rather non-trivial task). + /// + /// For example, in the trait object `dyn fmt::Debug + Sync`, the + /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds + /// are the set `{Sync}`. + /// + /// It is also possible to have a "trivial" trait object that + /// consists only of auto traits, with no principal - for example, + /// `dyn Send + Sync`. In that case, the set of auto-trait bounds + /// is `{Send, Sync}`, while there is no principal. These trait objects + /// have a "trivial" vtable consisting of just the size, alignment, + /// and destructor. + pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> { + match self[0] { + ExistentialPredicate::Trait(tr) => Some(tr), + _ => None, + } + } + + pub fn principal_def_id(&self) -> Option<DefId> { + self.principal().map(|trait_ref| trait_ref.def_id) + } + + #[inline] + pub fn projection_bounds<'a>( + &'a self, + ) -> impl Iterator<Item = ExistentialProjection<'tcx>> + 'a { + self.iter().filter_map(|predicate| match predicate { + ExistentialPredicate::Projection(projection) => Some(projection), + _ => None, + }) + } + + #[inline] + pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a { + self.iter().filter_map(|predicate| match predicate { + ExistentialPredicate::AutoTrait(did) => Some(did), + _ => None, + }) + } +} + +impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> { + pub fn principal(&self) -> Option<ty::Binder<ExistentialTraitRef<'tcx>>> { + self.skip_binder().principal().map(Binder::bind) + } + + pub fn principal_def_id(&self) -> Option<DefId> { + self.skip_binder().principal_def_id() + } + + #[inline] + pub fn projection_bounds<'a>( + &'a self, + ) -> impl Iterator<Item = PolyExistentialProjection<'tcx>> + 'a { + self.skip_binder().projection_bounds().map(Binder::bind) + } + + #[inline] + pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a { + self.skip_binder().auto_traits() + } + + pub fn iter<'a>( + &'a self, + ) -> impl DoubleEndedIterator<Item = Binder<ExistentialPredicate<'tcx>>> + 'tcx { + self.skip_binder().iter().map(Binder::bind) + } +} + +/// A complete reference to a trait. These take numerous guises in syntax, +/// but perhaps the most recognizable form is in a where-clause: +/// +/// T: Foo<U> +/// +/// This would be represented by a trait-reference where the `DefId` is the +/// `DefId` for the trait `Foo` and the substs define `T` as parameter 0, +/// and `U` as parameter 1. +/// +/// Trait references also appear in object types like `Foo<U>`, but in +/// that case the `Self` parameter is absent from the substitutions. +#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct TraitRef<'tcx> { + pub def_id: DefId, + pub substs: SubstsRef<'tcx>, +} + +impl<'tcx> TraitRef<'tcx> { + pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> { + TraitRef { def_id, substs } + } + + /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi` + /// are the parameters defined on trait. + pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> TraitRef<'tcx> { + TraitRef { def_id, substs: InternalSubsts::identity_for_item(tcx, def_id) } + } + + #[inline] + pub fn self_ty(&self) -> Ty<'tcx> { + self.substs.type_at(0) + } + + pub fn from_method( + tcx: TyCtxt<'tcx>, + trait_id: DefId, + substs: SubstsRef<'tcx>, + ) -> ty::TraitRef<'tcx> { + let defs = tcx.generics_of(trait_id); + + ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) } + } +} + +pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>; + +impl<'tcx> PolyTraitRef<'tcx> { + pub fn self_ty(&self) -> Binder<Ty<'tcx>> { + self.map_bound_ref(|tr| tr.self_ty()) + } + + pub fn def_id(&self) -> DefId { + self.skip_binder().def_id + } + + pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> { + // Note that we preserve binding levels + Binder(ty::TraitPredicate { trait_ref: self.skip_binder() }) + } +} + +/// An existential reference to a trait, where `Self` is erased. +/// For example, the trait object `Trait<'a, 'b, X, Y>` is: +/// +/// exists T. T: Trait<'a, 'b, X, Y> +/// +/// The substitutions don't include the erased `Self`, only trait +/// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above). +#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct ExistentialTraitRef<'tcx> { + pub def_id: DefId, + pub substs: SubstsRef<'tcx>, +} + +impl<'tcx> ExistentialTraitRef<'tcx> { + pub fn erase_self_ty( + tcx: TyCtxt<'tcx>, + trait_ref: ty::TraitRef<'tcx>, + ) -> ty::ExistentialTraitRef<'tcx> { + // Assert there is a Self. + trait_ref.substs.type_at(0); + + ty::ExistentialTraitRef { + def_id: trait_ref.def_id, + substs: tcx.intern_substs(&trait_ref.substs[1..]), + } + } + + /// Object types don't have a self type specified. Therefore, when + /// we convert the principal trait-ref into a normal trait-ref, + /// you must give *some* self type. A common choice is `mk_err()` + /// or some placeholder type. + pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> { + // otherwise the escaping vars would be captured by the binder + // debug_assert!(!self_ty.has_escaping_bound_vars()); + + ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) } + } +} + +pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>; + +impl<'tcx> PolyExistentialTraitRef<'tcx> { + pub fn def_id(&self) -> DefId { + self.skip_binder().def_id + } + + /// Object types don't have a self type specified. Therefore, when + /// we convert the principal trait-ref into a normal trait-ref, + /// you must give *some* self type. A common choice is `mk_err()` + /// or some placeholder type. + pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> { + self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty)) + } +} + +/// Binder is a binder for higher-ranked lifetimes or types. It is part of the +/// compiler's representation for things like `for<'a> Fn(&'a isize)` +/// (which would be represented by the type `PolyTraitRef == +/// Binder<TraitRef>`). Note that when we instantiate, +/// erase, or otherwise "discharge" these bound vars, we change the +/// type from `Binder<T>` to just `T` (see +/// e.g., `liberate_late_bound_regions`). +#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] +pub struct Binder<T>(T); + +impl<T> Binder<T> { + /// Wraps `value` in a binder, asserting that `value` does not + /// contain any bound vars that would be bound by the + /// binder. This is commonly used to 'inject' a value T into a + /// different binding level. + pub fn dummy<'tcx>(value: T) -> Binder<T> + where + T: TypeFoldable<'tcx>, + { + debug_assert!(!value.has_escaping_bound_vars()); + Binder(value) + } + + /// Wraps `value` in a binder, binding higher-ranked vars (if any). + pub fn bind(value: T) -> Binder<T> { + Binder(value) + } + + /// Wraps `value` in a binder without actually binding any currently + /// unbound variables. + /// + /// Note that this will shift all debrujin indices of escaping bound variables + /// by 1 to avoid accidential captures. + pub fn wrap_nonbinding(tcx: TyCtxt<'tcx>, value: T) -> Binder<T> + where + T: TypeFoldable<'tcx>, + { + if value.has_escaping_bound_vars() { + Binder::bind(super::fold::shift_vars(tcx, &value, 1)) + } else { + Binder::dummy(value) + } + } + + /// Skips the binder and returns the "bound" value. This is a + /// risky thing to do because it's easy to get confused about + /// De Bruijn indices and the like. It is usually better to + /// discharge the binder using `no_bound_vars` or + /// `replace_late_bound_regions` or something like + /// that. `skip_binder` is only valid when you are either + /// extracting data that has nothing to do with bound vars, you + /// are doing some sort of test that does not involve bound + /// regions, or you are being very careful about your depth + /// accounting. + /// + /// Some examples where `skip_binder` is reasonable: + /// + /// - extracting the `DefId` from a PolyTraitRef; + /// - comparing the self type of a PolyTraitRef to see if it is equal to + /// a type parameter `X`, since the type `X` does not reference any regions + pub fn skip_binder(self) -> T { + self.0 + } + + pub fn as_ref(&self) -> Binder<&T> { + Binder(&self.0) + } + + pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U> + where + F: FnOnce(&T) -> U, + { + self.as_ref().map_bound(f) + } + + pub fn map_bound<F, U>(self, f: F) -> Binder<U> + where + F: FnOnce(T) -> U, + { + Binder(f(self.0)) + } + + /// Unwraps and returns the value within, but only if it contains + /// no bound vars at all. (In other words, if this binder -- + /// and indeed any enclosing binder -- doesn't bind anything at + /// all.) Otherwise, returns `None`. + /// + /// (One could imagine having a method that just unwraps a single + /// binder, but permits late-bound vars bound by enclosing + /// binders, but that would require adjusting the debruijn + /// indices, and given the shallow binding structure we often use, + /// would not be that useful.) + pub fn no_bound_vars<'tcx>(self) -> Option<T> + where + T: TypeFoldable<'tcx>, + { + if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) } + } + + /// Given two things that have the same binder level, + /// and an operation that wraps on their contents, executes the operation + /// and then wraps its result. + /// + /// `f` should consider bound regions at depth 1 to be free, and + /// anything it produces with bound regions at depth 1 will be + /// bound in the resulting return value. + pub fn fuse<U, F, R>(self, u: Binder<U>, f: F) -> Binder<R> + where + F: FnOnce(T, U) -> R, + { + Binder(f(self.0, u.0)) + } + + /// Splits the contents into two things that share the same binder + /// level as the original, returning two distinct binders. + /// + /// `f` should consider bound regions at depth 1 to be free, and + /// anything it produces with bound regions at depth 1 will be + /// bound in the resulting return values. + pub fn split<U, V, F>(self, f: F) -> (Binder<U>, Binder<V>) + where + F: FnOnce(T) -> (U, V), + { + let (u, v) = f(self.0); + (Binder(u), Binder(v)) + } +} + +impl<T> Binder<Option<T>> { + pub fn transpose(self) -> Option<Binder<T>> { + match self.0 { + Some(v) => Some(Binder(v)), + None => None, + } + } +} + +/// Represents the projection of an associated type. In explicit UFCS +/// form this would be written `<T as Trait<..>>::N`. +#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct ProjectionTy<'tcx> { + /// The parameters of the associated item. + pub substs: SubstsRef<'tcx>, + + /// The `DefId` of the `TraitItem` for the associated type `N`. + /// + /// Note that this is not the `DefId` of the `TraitRef` containing this + /// associated type, which is in `tcx.associated_item(item_def_id).container`. + pub item_def_id: DefId, +} + +impl<'tcx> ProjectionTy<'tcx> { + /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the + /// associated item named `item_name`. + pub fn from_ref_and_name( + tcx: TyCtxt<'_>, + trait_ref: ty::TraitRef<'tcx>, + item_name: Ident, + ) -> ProjectionTy<'tcx> { + let item_def_id = tcx + .associated_items(trait_ref.def_id) + .find_by_name_and_kind(tcx, item_name, ty::AssocKind::Type, trait_ref.def_id) + .unwrap() + .def_id; + + ProjectionTy { substs: trait_ref.substs, item_def_id } + } + + /// Extracts the underlying trait reference from this projection. + /// For example, if this is a projection of `<T as Iterator>::Item`, + /// then this function would return a `T: Iterator` trait reference. + pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> { + let def_id = tcx.associated_item(self.item_def_id).container.id(); + ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) } + } + + pub fn self_ty(&self) -> Ty<'tcx> { + self.substs.type_at(0) + } +} + +#[derive(Copy, Clone, Debug, TypeFoldable)] +pub struct GenSig<'tcx> { + pub resume_ty: Ty<'tcx>, + pub yield_ty: Ty<'tcx>, + pub return_ty: Ty<'tcx>, +} + +pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>; + +impl<'tcx> PolyGenSig<'tcx> { + pub fn resume_ty(&self) -> ty::Binder<Ty<'tcx>> { + self.map_bound_ref(|sig| sig.resume_ty) + } + pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> { + self.map_bound_ref(|sig| sig.yield_ty) + } + pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> { + self.map_bound_ref(|sig| sig.return_ty) + } +} + +/// Signature of a function type, which we have arbitrarily +/// decided to use to refer to the input/output types. +/// +/// - `inputs`: is the list of arguments and their modes. +/// - `output`: is the return type. +/// - `c_variadic`: indicates whether this is a C-variadic function. +#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct FnSig<'tcx> { + pub inputs_and_output: &'tcx List<Ty<'tcx>>, + pub c_variadic: bool, + pub unsafety: hir::Unsafety, + pub abi: abi::Abi, +} + +impl<'tcx> FnSig<'tcx> { + pub fn inputs(&self) -> &'tcx [Ty<'tcx>] { + &self.inputs_and_output[..self.inputs_and_output.len() - 1] + } + + pub fn output(&self) -> Ty<'tcx> { + self.inputs_and_output[self.inputs_and_output.len() - 1] + } + + // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible + // method. + fn fake() -> FnSig<'tcx> { + FnSig { + inputs_and_output: List::empty(), + c_variadic: false, + unsafety: hir::Unsafety::Normal, + abi: abi::Abi::Rust, + } + } +} + +pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>; + +impl<'tcx> PolyFnSig<'tcx> { + #[inline] + pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> { + self.map_bound_ref(|fn_sig| fn_sig.inputs()) + } + #[inline] + pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> { + self.map_bound_ref(|fn_sig| fn_sig.inputs()[index]) + } + pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> { + self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output) + } + #[inline] + pub fn output(&self) -> ty::Binder<Ty<'tcx>> { + self.map_bound_ref(|fn_sig| fn_sig.output()) + } + pub fn c_variadic(&self) -> bool { + self.skip_binder().c_variadic + } + pub fn unsafety(&self) -> hir::Unsafety { + self.skip_binder().unsafety + } + pub fn abi(&self) -> abi::Abi { + self.skip_binder().abi + } +} + +pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>; + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub struct ParamTy { + pub index: u32, + pub name: Symbol, +} + +impl<'tcx> ParamTy { + pub fn new(index: u32, name: Symbol) -> ParamTy { + ParamTy { index, name } + } + + pub fn for_self() -> ParamTy { + ParamTy::new(0, kw::SelfUpper) + } + + pub fn for_def(def: &ty::GenericParamDef) -> ParamTy { + ParamTy::new(def.index, def.name) + } + + pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + tcx.mk_ty_param(self.index, self.name) + } +} + +#[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)] +#[derive(HashStable)] +pub struct ParamConst { + pub index: u32, + pub name: Symbol, +} + +impl<'tcx> ParamConst { + pub fn new(index: u32, name: Symbol) -> ParamConst { + ParamConst { index, name } + } + + pub fn for_def(def: &ty::GenericParamDef) -> ParamConst { + ParamConst::new(def.index, def.name) + } + + pub fn to_const(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx ty::Const<'tcx> { + tcx.mk_const_param(self.index, self.name, ty) + } +} + +rustc_index::newtype_index! { + /// A [De Bruijn index][dbi] is a standard means of representing + /// regions (and perhaps later types) in a higher-ranked setting. In + /// particular, imagine a type like this: + /// + /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char) + /// ^ ^ | | | + /// | | | | | + /// | +------------+ 0 | | + /// | | | + /// +--------------------------------+ 1 | + /// | | + /// +------------------------------------------+ 0 + /// + /// In this type, there are two binders (the outer fn and the inner + /// fn). We need to be able to determine, for any given region, which + /// fn type it is bound by, the inner or the outer one. There are + /// various ways you can do this, but a De Bruijn index is one of the + /// more convenient and has some nice properties. The basic idea is to + /// count the number of binders, inside out. Some examples should help + /// clarify what I mean. + /// + /// Let's start with the reference type `&'b isize` that is the first + /// argument to the inner function. This region `'b` is assigned a De + /// Bruijn index of 0, meaning "the innermost binder" (in this case, a + /// fn). The region `'a` that appears in the second argument type (`&'a + /// isize`) would then be assigned a De Bruijn index of 1, meaning "the + /// second-innermost binder". (These indices are written on the arrays + /// in the diagram). + /// + /// What is interesting is that De Bruijn index attached to a particular + /// variable will vary depending on where it appears. For example, + /// the final type `&'a char` also refers to the region `'a` declared on + /// the outermost fn. But this time, this reference is not nested within + /// any other binders (i.e., it is not an argument to the inner fn, but + /// rather the outer one). Therefore, in this case, it is assigned a + /// De Bruijn index of 0, because the innermost binder in that location + /// is the outer fn. + /// + /// [dbi]: https://en.wikipedia.org/wiki/De_Bruijn_index + #[derive(HashStable)] + pub struct DebruijnIndex { + DEBUG_FORMAT = "DebruijnIndex({})", + const INNERMOST = 0, + } +} + +pub type Region<'tcx> = &'tcx RegionKind; + +/// Representation of regions. Note that the NLL checker uses a distinct +/// representation of regions. For this reason, it internally replaces all the +/// regions with inference variables -- the index of the variable is then used +/// to index into internal NLL data structures. See `rustc_mir::borrow_check` +/// module for more information. +/// +/// ## The Region lattice within a given function +/// +/// In general, the region lattice looks like +/// +/// ``` +/// static ----------+-----...------+ (greatest) +/// | | | +/// early-bound and | | +/// free regions | | +/// | | | +/// | | | +/// empty(root) placeholder(U1) | +/// | / | +/// | / placeholder(Un) +/// empty(U1) -- / +/// | / +/// ... / +/// | / +/// empty(Un) -------- (smallest) +/// ``` +/// +/// Early-bound/free regions are the named lifetimes in scope from the +/// function declaration. They have relationships to one another +/// determined based on the declared relationships from the +/// function. +/// +/// Note that inference variables and bound regions are not included +/// in this diagram. In the case of inference variables, they should +/// be inferred to some other region from the diagram. In the case of +/// bound regions, they are excluded because they don't make sense to +/// include -- the diagram indicates the relationship between free +/// regions. +/// +/// ## Inference variables +/// +/// During region inference, we sometimes create inference variables, +/// represented as `ReVar`. These will be inferred by the code in +/// `infer::lexical_region_resolve` to some free region from the +/// lattice above (the minimal region that meets the +/// constraints). +/// +/// During NLL checking, where regions are defined differently, we +/// also use `ReVar` -- in that case, the index is used to index into +/// the NLL region checker's data structures. The variable may in fact +/// represent either a free region or an inference variable, in that +/// case. +/// +/// ## Bound Regions +/// +/// These are regions that are stored behind a binder and must be substituted +/// with some concrete region before being used. There are two kind of +/// bound regions: early-bound, which are bound in an item's `Generics`, +/// and are substituted by a `InternalSubsts`, and late-bound, which are part of +/// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by +/// the likes of `liberate_late_bound_regions`. The distinction exists +/// because higher-ranked lifetimes aren't supported in all places. See [1][2]. +/// +/// Unlike `Param`s, bound regions are not supposed to exist "in the wild" +/// outside their binder, e.g., in types passed to type inference, and +/// should first be substituted (by placeholder regions, free regions, +/// or region variables). +/// +/// ## Placeholder and Free Regions +/// +/// One often wants to work with bound regions without knowing their precise +/// identity. For example, when checking a function, the lifetime of a borrow +/// can end up being assigned to some region parameter. In these cases, +/// it must be ensured that bounds on the region can't be accidentally +/// assumed without being checked. +/// +/// To do this, we replace the bound regions with placeholder markers, +/// which don't satisfy any relation not explicitly provided. +/// +/// There are two kinds of placeholder regions in rustc: `ReFree` and +/// `RePlaceholder`. When checking an item's body, `ReFree` is supposed +/// to be used. These also support explicit bounds: both the internally-stored +/// *scope*, which the region is assumed to outlive, as well as other +/// relations stored in the `FreeRegionMap`. Note that these relations +/// aren't checked when you `make_subregion` (or `eq_types`), only by +/// `resolve_regions_and_report_errors`. +/// +/// When working with higher-ranked types, some region relations aren't +/// yet known, so you can't just call `resolve_regions_and_report_errors`. +/// `RePlaceholder` is designed for this purpose. In these contexts, +/// there's also the risk that some inference variable laying around will +/// get unified with your placeholder region: if you want to check whether +/// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a` +/// with a placeholder region `'%a`, the variable `'_` would just be +/// instantiated to the placeholder region `'%a`, which is wrong because +/// the inference variable is supposed to satisfy the relation +/// *for every value of the placeholder region*. To ensure that doesn't +/// happen, you can use `leak_check`. This is more clearly explained +/// by the [rustc dev guide]. +/// +/// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/ +/// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/ +/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html +#[derive(Clone, PartialEq, Eq, Hash, Copy, TyEncodable, TyDecodable, PartialOrd, Ord)] +pub enum RegionKind { + /// Region bound in a type or fn declaration which will be + /// substituted 'early' -- that is, at the same time when type + /// parameters are substituted. + ReEarlyBound(EarlyBoundRegion), + + /// Region bound in a function scope, which will be substituted when the + /// function is called. + ReLateBound(DebruijnIndex, BoundRegion), + + /// When checking a function body, the types of all arguments and so forth + /// that refer to bound region parameters are modified to refer to free + /// region parameters. + ReFree(FreeRegion), + + /// Static data that has an "infinite" lifetime. Top in the region lattice. + ReStatic, + + /// A region variable. Should not exist after typeck. + ReVar(RegionVid), + + /// A placeholder region -- basically, the higher-ranked version of `ReFree`. + /// Should not exist after typeck. + RePlaceholder(ty::PlaceholderRegion), + + /// Empty lifetime is for data that is never accessed. We tag the + /// empty lifetime with a universe -- the idea is that we don't + /// want `exists<'a> { forall<'b> { 'b: 'a } }` to be satisfiable. + /// Therefore, the `'empty` in a universe `U` is less than all + /// regions visible from `U`, but not less than regions not visible + /// from `U`. + ReEmpty(ty::UniverseIndex), + + /// Erased region, used by trait selection, in MIR and during codegen. + ReErased, +} + +#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)] +pub struct EarlyBoundRegion { + pub def_id: DefId, + pub index: u32, + pub name: Symbol, +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +pub struct TyVid { + pub index: u32, +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +pub struct ConstVid<'tcx> { + pub index: u32, + pub phantom: PhantomData<&'tcx ()>, +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +pub struct IntVid { + pub index: u32, +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +pub struct FloatVid { + pub index: u32, +} + +rustc_index::newtype_index! { + pub struct RegionVid { + DEBUG_FORMAT = custom, + } +} + +impl Atom for RegionVid { + fn index(self) -> usize { + Idx::index(self) + } +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub enum InferTy { + TyVar(TyVid), + IntVar(IntVid), + FloatVar(FloatVid), + + /// A `FreshTy` is one that is generated as a replacement for an + /// unbound type variable. This is convenient for caching etc. See + /// `infer::freshen` for more details. + FreshTy(u32), + FreshIntTy(u32), + FreshFloatTy(u32), +} + +rustc_index::newtype_index! { + pub struct BoundVar { .. } +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub struct BoundTy { + pub var: BoundVar, + pub kind: BoundTyKind, +} + +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable)] +pub enum BoundTyKind { + Anon, + Param(Symbol), +} + +impl From<BoundVar> for BoundTy { + fn from(var: BoundVar) -> Self { + BoundTy { var, kind: BoundTyKind::Anon } + } +} + +/// A `ProjectionPredicate` for an `ExistentialTraitRef`. +#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable)] +pub struct ExistentialProjection<'tcx> { + pub item_def_id: DefId, + pub substs: SubstsRef<'tcx>, + pub ty: Ty<'tcx>, +} + +pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>; + +impl<'tcx> ExistentialProjection<'tcx> { + /// Extracts the underlying existential trait reference from this projection. + /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`, + /// then this function would return a `exists T. T: Iterator` existential trait + /// reference. + pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::ExistentialTraitRef<'tcx> { + let def_id = tcx.associated_item(self.item_def_id).container.id(); + ty::ExistentialTraitRef { def_id, substs: self.substs } + } + + pub fn with_self_ty( + &self, + tcx: TyCtxt<'tcx>, + self_ty: Ty<'tcx>, + ) -> ty::ProjectionPredicate<'tcx> { + // otherwise the escaping regions would be captured by the binders + debug_assert!(!self_ty.has_escaping_bound_vars()); + + ty::ProjectionPredicate { + projection_ty: ty::ProjectionTy { + item_def_id: self.item_def_id, + substs: tcx.mk_substs_trait(self_ty, self.substs), + }, + ty: self.ty, + } + } +} + +impl<'tcx> PolyExistentialProjection<'tcx> { + pub fn with_self_ty( + &self, + tcx: TyCtxt<'tcx>, + self_ty: Ty<'tcx>, + ) -> ty::PolyProjectionPredicate<'tcx> { + self.map_bound(|p| p.with_self_ty(tcx, self_ty)) + } + + pub fn item_def_id(&self) -> DefId { + self.skip_binder().item_def_id + } +} + +impl DebruijnIndex { + /// Returns the resulting index when this value is moved into + /// `amount` number of new binders. So, e.g., if you had + /// + /// for<'a> fn(&'a x) + /// + /// and you wanted to change it to + /// + /// for<'a> fn(for<'b> fn(&'a x)) + /// + /// you would need to shift the index for `'a` into a new binder. + #[must_use] + pub fn shifted_in(self, amount: u32) -> DebruijnIndex { + DebruijnIndex::from_u32(self.as_u32() + amount) + } + + /// Update this index in place by shifting it "in" through + /// `amount` number of binders. + pub fn shift_in(&mut self, amount: u32) { + *self = self.shifted_in(amount); + } + + /// Returns the resulting index when this value is moved out from + /// `amount` number of new binders. + #[must_use] + pub fn shifted_out(self, amount: u32) -> DebruijnIndex { + DebruijnIndex::from_u32(self.as_u32() - amount) + } + + /// Update in place by shifting out from `amount` binders. + pub fn shift_out(&mut self, amount: u32) { + *self = self.shifted_out(amount); + } + + /// Adjusts any De Bruijn indices so as to make `to_binder` the + /// innermost binder. That is, if we have something bound at `to_binder`, + /// it will now be bound at INNERMOST. This is an appropriate thing to do + /// when moving a region out from inside binders: + /// + /// ``` + /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _) + /// // Binder: D3 D2 D1 ^^ + /// ``` + /// + /// Here, the region `'a` would have the De Bruijn index D3, + /// because it is the bound 3 binders out. However, if we wanted + /// to refer to that region `'a` in the second argument (the `_`), + /// those two binders would not be in scope. In that case, we + /// might invoke `shift_out_to_binder(D3)`. This would adjust the + /// De Bruijn index of `'a` to D1 (the innermost binder). + /// + /// If we invoke `shift_out_to_binder` and the region is in fact + /// bound by one of the binders we are shifting out of, that is an + /// error (and should fail an assertion failure). + pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self { + self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32()) + } +} + +/// Region utilities +impl RegionKind { + /// Is this region named by the user? + pub fn has_name(&self) -> bool { + match *self { + RegionKind::ReEarlyBound(ebr) => ebr.has_name(), + RegionKind::ReLateBound(_, br) => br.is_named(), + RegionKind::ReFree(fr) => fr.bound_region.is_named(), + RegionKind::ReStatic => true, + RegionKind::ReVar(..) => false, + RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(), + RegionKind::ReEmpty(_) => false, + RegionKind::ReErased => false, + } + } + + pub fn is_late_bound(&self) -> bool { + match *self { + ty::ReLateBound(..) => true, + _ => false, + } + } + + pub fn is_placeholder(&self) -> bool { + match *self { + ty::RePlaceholder(..) => true, + _ => false, + } + } + + pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool { + match *self { + ty::ReLateBound(debruijn, _) => debruijn >= index, + _ => false, + } + } + + /// Adjusts any De Bruijn indices so as to make `to_binder` the + /// innermost binder. That is, if we have something bound at `to_binder`, + /// it will now be bound at INNERMOST. This is an appropriate thing to do + /// when moving a region out from inside binders: + /// + /// ``` + /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _) + /// // Binder: D3 D2 D1 ^^ + /// ``` + /// + /// Here, the region `'a` would have the De Bruijn index D3, + /// because it is the bound 3 binders out. However, if we wanted + /// to refer to that region `'a` in the second argument (the `_`), + /// those two binders would not be in scope. In that case, we + /// might invoke `shift_out_to_binder(D3)`. This would adjust the + /// De Bruijn index of `'a` to D1 (the innermost binder). + /// + /// If we invoke `shift_out_to_binder` and the region is in fact + /// bound by one of the binders we are shifting out of, that is an + /// error (and should fail an assertion failure). + pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind { + match *self { + ty::ReLateBound(debruijn, r) => { + ty::ReLateBound(debruijn.shifted_out_to_binder(to_binder), r) + } + r => r, + } + } + + pub fn type_flags(&self) -> TypeFlags { + let mut flags = TypeFlags::empty(); + + match *self { + ty::ReVar(..) => { + flags = flags | TypeFlags::HAS_FREE_REGIONS; + flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; + flags = flags | TypeFlags::HAS_RE_INFER; + } + ty::RePlaceholder(..) => { + flags = flags | TypeFlags::HAS_FREE_REGIONS; + flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; + flags = flags | TypeFlags::HAS_RE_PLACEHOLDER; + } + ty::ReEarlyBound(..) => { + flags = flags | TypeFlags::HAS_FREE_REGIONS; + flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; + flags = flags | TypeFlags::HAS_RE_PARAM; + } + ty::ReFree { .. } => { + flags = flags | TypeFlags::HAS_FREE_REGIONS; + flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; + } + ty::ReEmpty(_) | ty::ReStatic => { + flags = flags | TypeFlags::HAS_FREE_REGIONS; + } + ty::ReLateBound(..) => { + flags = flags | TypeFlags::HAS_RE_LATE_BOUND; + } + ty::ReErased => { + flags = flags | TypeFlags::HAS_RE_ERASED; + } + } + + debug!("type_flags({:?}) = {:?}", self, flags); + + flags + } + + /// Given an early-bound or free region, returns the `DefId` where it was bound. + /// For example, consider the regions in this snippet of code: + /// + /// ``` + /// impl<'a> Foo { + /// ^^ -- early bound, declared on an impl + /// + /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c + /// ^^ ^^ ^ anonymous, late-bound + /// | early-bound, appears in where-clauses + /// late-bound, appears only in fn args + /// {..} + /// } + /// ``` + /// + /// Here, `free_region_binding_scope('a)` would return the `DefId` + /// of the impl, and for all the other highlighted regions, it + /// would return the `DefId` of the function. In other cases (not shown), this + /// function might return the `DefId` of a closure. + pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_>) -> DefId { + match self { + ty::ReEarlyBound(br) => tcx.parent(br.def_id).unwrap(), + ty::ReFree(fr) => fr.scope, + _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self), + } + } +} + +/// Type utilities +impl<'tcx> TyS<'tcx> { + #[inline] + pub fn is_unit(&self) -> bool { + match self.kind { + Tuple(ref tys) => tys.is_empty(), + _ => false, + } + } + + #[inline] + pub fn is_never(&self) -> bool { + match self.kind { + Never => true, + _ => false, + } + } + + /// Checks whether a type is definitely uninhabited. This is + /// conservative: for some types that are uninhabited we return `false`, + /// but we only return `true` for types that are definitely uninhabited. + /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty` + /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero + /// size, to account for partial initialisation. See #49298 for details.) + pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'tcx>) -> bool { + // FIXME(varkor): we can make this less conversative by substituting concrete + // type arguments. + match self.kind { + ty::Never => true, + ty::Adt(def, _) if def.is_union() => { + // For now, `union`s are never considered uninhabited. + false + } + ty::Adt(def, _) => { + // Any ADT is uninhabited if either: + // (a) It has no variants (i.e. an empty `enum`); + // (b) Each of its variants (a single one in the case of a `struct`) has at least + // one uninhabited field. + def.variants.iter().all(|var| { + var.fields.iter().any(|field| { + tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx) + }) + }) + } + ty::Tuple(..) => { + self.tuple_fields().any(|ty| ty.conservative_is_privately_uninhabited(tcx)) + } + ty::Array(ty, len) => { + match len.try_eval_usize(tcx, ParamEnv::empty()) { + // If the array is definitely non-empty, it's uninhabited if + // the type of its elements is uninhabited. + Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx), + _ => false, + } + } + ty::Ref(..) => { + // References to uninitialised memory is valid for any type, including + // uninhabited types, in unsafe code, so we treat all references as + // inhabited. + false + } + _ => false, + } + } + + #[inline] + pub fn is_primitive(&self) -> bool { + self.kind.is_primitive() + } + + #[inline] + pub fn is_ty_var(&self) -> bool { + match self.kind { + Infer(TyVar(_)) => true, + _ => false, + } + } + + #[inline] + pub fn is_ty_infer(&self) -> bool { + match self.kind { + Infer(_) => true, + _ => false, + } + } + + #[inline] + pub fn is_phantom_data(&self) -> bool { + if let Adt(def, _) = self.kind { def.is_phantom_data() } else { false } + } + + #[inline] + pub fn is_bool(&self) -> bool { + self.kind == Bool + } + + /// Returns `true` if this type is a `str`. + #[inline] + pub fn is_str(&self) -> bool { + self.kind == Str + } + + #[inline] + pub fn is_param(&self, index: u32) -> bool { + match self.kind { + ty::Param(ref data) => data.index == index, + _ => false, + } + } + + #[inline] + pub fn is_slice(&self) -> bool { + match self.kind { + RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.kind { + Slice(_) | Str => true, + _ => false, + }, + _ => false, + } + } + + #[inline] + pub fn is_simd(&self) -> bool { + match self.kind { + Adt(def, _) => def.repr.simd(), + _ => false, + } + } + + pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + match self.kind { + Array(ty, _) | Slice(ty) => ty, + Str => tcx.mk_mach_uint(ast::UintTy::U8), + _ => bug!("`sequence_element_type` called on non-sequence value: {}", self), + } + } + + pub fn simd_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + match self.kind { + Adt(def, substs) => def.non_enum_variant().fields[0].ty(tcx, substs), + _ => bug!("`simd_type` called on invalid type"), + } + } + + pub fn simd_size(&self, _tcx: TyCtxt<'tcx>) -> u64 { + // Parameter currently unused, but probably needed in the future to + // allow `#[repr(simd)] struct Simd<T, const N: usize>([T; N]);`. + match self.kind { + Adt(def, _) => def.non_enum_variant().fields.len() as u64, + _ => bug!("`simd_size` called on invalid type"), + } + } + + pub fn simd_size_and_type(&self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) { + match self.kind { + Adt(def, substs) => { + let variant = def.non_enum_variant(); + (variant.fields.len() as u64, variant.fields[0].ty(tcx, substs)) + } + _ => bug!("`simd_size_and_type` called on invalid type"), + } + } + + #[inline] + pub fn is_region_ptr(&self) -> bool { + match self.kind { + Ref(..) => true, + _ => false, + } + } + + #[inline] + pub fn is_mutable_ptr(&self) -> bool { + match self.kind { + RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. }) + | Ref(_, _, hir::Mutability::Mut) => true, + _ => false, + } + } + + #[inline] + pub fn is_unsafe_ptr(&self) -> bool { + match self.kind { + RawPtr(_) => true, + _ => false, + } + } + + /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer). + #[inline] + pub fn is_any_ptr(&self) -> bool { + self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr() + } + + #[inline] + pub fn is_box(&self) -> bool { + match self.kind { + Adt(def, _) => def.is_box(), + _ => false, + } + } + + /// Panics if called on any type other than `Box<T>`. + pub fn boxed_ty(&self) -> Ty<'tcx> { + match self.kind { + Adt(def, substs) if def.is_box() => substs.type_at(0), + _ => bug!("`boxed_ty` is called on non-box type {:?}", self), + } + } + + /// A scalar type is one that denotes an atomic datum, with no sub-components. + /// (A RawPtr is scalar because it represents a non-managed pointer, so its + /// contents are abstract to rustc.) + #[inline] + pub fn is_scalar(&self) -> bool { + match self.kind { + Bool + | Char + | Int(_) + | Float(_) + | Uint(_) + | Infer(IntVar(_) | FloatVar(_)) + | FnDef(..) + | FnPtr(_) + | RawPtr(_) => true, + _ => false, + } + } + + /// Returns `true` if this type is a floating point type. + #[inline] + pub fn is_floating_point(&self) -> bool { + match self.kind { + Float(_) | Infer(FloatVar(_)) => true, + _ => false, + } + } + + #[inline] + pub fn is_trait(&self) -> bool { + match self.kind { + Dynamic(..) => true, + _ => false, + } + } + + #[inline] + pub fn is_enum(&self) -> bool { + match self.kind { + Adt(adt_def, _) => adt_def.is_enum(), + _ => false, + } + } + + #[inline] + pub fn is_closure(&self) -> bool { + match self.kind { + Closure(..) => true, + _ => false, + } + } + + #[inline] + pub fn is_generator(&self) -> bool { + match self.kind { + Generator(..) => true, + _ => false, + } + } + + #[inline] + pub fn is_integral(&self) -> bool { + match self.kind { + Infer(IntVar(_)) | Int(_) | Uint(_) => true, + _ => false, + } + } + + #[inline] + pub fn is_fresh_ty(&self) -> bool { + match self.kind { + Infer(FreshTy(_)) => true, + _ => false, + } + } + + #[inline] + pub fn is_fresh(&self) -> bool { + match self.kind { + Infer(FreshTy(_)) => true, + Infer(FreshIntTy(_)) => true, + Infer(FreshFloatTy(_)) => true, + _ => false, + } + } + + #[inline] + pub fn is_char(&self) -> bool { + match self.kind { + Char => true, + _ => false, + } + } + + #[inline] + pub fn is_numeric(&self) -> bool { + self.is_integral() || self.is_floating_point() + } + + #[inline] + pub fn is_signed(&self) -> bool { + match self.kind { + Int(_) => true, + _ => false, + } + } + + #[inline] + pub fn is_ptr_sized_integral(&self) -> bool { + match self.kind { + Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true, + _ => false, + } + } + + #[inline] + pub fn is_machine(&self) -> bool { + match self.kind { + Int(..) | Uint(..) | Float(..) => true, + _ => false, + } + } + + #[inline] + pub fn has_concrete_skeleton(&self) -> bool { + match self.kind { + Param(_) | Infer(_) | Error(_) => false, + _ => true, + } + } + + /// Returns the type and mutability of `*ty`. + /// + /// The parameter `explicit` indicates if this is an *explicit* dereference. + /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly. + pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> { + match self.kind { + Adt(def, _) if def.is_box() => { + Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not }) + } + Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }), + RawPtr(mt) if explicit => Some(mt), + _ => None, + } + } + + /// Returns the type of `ty[i]`. + pub fn builtin_index(&self) -> Option<Ty<'tcx>> { + match self.kind { + Array(ty, _) | Slice(ty) => Some(ty), + _ => None, + } + } + + pub fn fn_sig(&self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> { + match self.kind { + FnDef(def_id, substs) => tcx.fn_sig(def_id).subst(tcx, substs), + FnPtr(f) => f, + Error(_) => { + // ignore errors (#54954) + ty::Binder::dummy(FnSig::fake()) + } + Closure(..) => bug!( + "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`", + ), + _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self), + } + } + + #[inline] + pub fn is_fn(&self) -> bool { + match self.kind { + FnDef(..) | FnPtr(_) => true, + _ => false, + } + } + + #[inline] + pub fn is_fn_ptr(&self) -> bool { + match self.kind { + FnPtr(_) => true, + _ => false, + } + } + + #[inline] + pub fn is_impl_trait(&self) -> bool { + match self.kind { + Opaque(..) => true, + _ => false, + } + } + + #[inline] + pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> { + match self.kind { + Adt(adt, _) => Some(adt), + _ => None, + } + } + + /// Iterates over tuple fields. + /// Panics when called on anything but a tuple. + pub fn tuple_fields(&self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> { + match self.kind { + Tuple(substs) => substs.iter().map(|field| field.expect_ty()), + _ => bug!("tuple_fields called on non-tuple"), + } + } + + /// If the type contains variants, returns the valid range of variant indices. + // + // FIXME: This requires the optimized MIR in the case of generators. + #[inline] + pub fn variant_range(&self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> { + match self.kind { + TyKind::Adt(adt, _) => Some(adt.variant_range()), + TyKind::Generator(def_id, substs, _) => { + Some(substs.as_generator().variant_range(def_id, tcx)) + } + _ => None, + } + } + + /// If the type contains variants, returns the variant for `variant_index`. + /// Panics if `variant_index` is out of range. + // + // FIXME: This requires the optimized MIR in the case of generators. + #[inline] + pub fn discriminant_for_variant( + &self, + tcx: TyCtxt<'tcx>, + variant_index: VariantIdx, + ) -> Option<Discr<'tcx>> { + match self.kind { + TyKind::Adt(adt, _) if adt.variants.is_empty() => { + bug!("discriminant_for_variant called on zero variant enum"); + } + TyKind::Adt(adt, _) if adt.is_enum() => { + Some(adt.discriminant_for_variant(tcx, variant_index)) + } + TyKind::Generator(def_id, substs, _) => { + Some(substs.as_generator().discriminant_for_variant(def_id, tcx, variant_index)) + } + _ => None, + } + } + + /// Returns the type of the discriminant of this type. + pub fn discriminant_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + match self.kind { + ty::Adt(adt, _) if adt.is_enum() => adt.repr.discr_type().to_ty(tcx), + ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx), + _ => { + // This can only be `0`, for now, so `u8` will suffice. + tcx.types.u8 + } + } + } + + /// When we create a closure, we record its kind (i.e., what trait + /// it implements) into its `ClosureSubsts` using a type + /// parameter. This is kind of a phantom type, except that the + /// most convenient thing for us to are the integral types. This + /// function converts such a special type into the closure + /// kind. To go the other way, use + /// `tcx.closure_kind_ty(closure_kind)`. + /// + /// Note that during type checking, we use an inference variable + /// to represent the closure kind, because it has not yet been + /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`) + /// is complete, that type variable will be unified. + pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> { + match self.kind { + Int(int_ty) => match int_ty { + ast::IntTy::I8 => Some(ty::ClosureKind::Fn), + ast::IntTy::I16 => Some(ty::ClosureKind::FnMut), + ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce), + _ => bug!("cannot convert type `{:?}` to a closure kind", self), + }, + + // "Bound" types appear in canonical queries when the + // closure type is not yet known + Bound(..) | Infer(_) => None, + + Error(_) => Some(ty::ClosureKind::Fn), + + _ => bug!("cannot convert type `{:?}` to a closure kind", self), + } + } + + /// Fast path helper for testing if a type is `Sized`. + /// + /// Returning true means the type is known to be sized. Returning + /// `false` means nothing -- could be sized, might not be. + pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx>) -> bool { + match self.kind { + ty::Infer(ty::IntVar(_) | ty::FloatVar(_)) + | ty::Uint(_) + | ty::Int(_) + | ty::Bool + | ty::Float(_) + | ty::FnDef(..) + | ty::FnPtr(_) + | ty::RawPtr(..) + | ty::Char + | ty::Ref(..) + | ty::Generator(..) + | ty::GeneratorWitness(..) + | ty::Array(..) + | ty::Closure(..) + | ty::Never + | ty::Error(_) => true, + + ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false, + + ty::Tuple(tys) => tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx)), + + ty::Adt(def, _substs) => def.sized_constraint(tcx).is_empty(), + + ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false, + + ty::Infer(ty::TyVar(_)) => false, + + ty::Bound(..) + | ty::Placeholder(..) + | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => { + bug!("`is_trivially_sized` applied to unexpected type: {:?}", self) + } + } + } + + /// Is this a zero-sized type? + pub fn is_zst(&'tcx self, tcx: TyCtxt<'tcx>, did: DefId) -> bool { + tcx.layout_of(tcx.param_env(did).and(self)).map(|layout| layout.is_zst()).unwrap_or(false) + } +} diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs new file mode 100644 index 00000000000..acd58ab7f96 --- /dev/null +++ b/compiler/rustc_middle/src/ty/subst.rs @@ -0,0 +1,687 @@ +// Type substitutions. + +use crate::infer::canonical::Canonical; +use crate::ty::codec::{TyDecoder, TyEncoder}; +use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor}; +use crate::ty::sty::{ClosureSubsts, GeneratorSubsts}; +use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt}; + +use rustc_hir::def_id::DefId; +use rustc_macros::HashStable; +use rustc_serialize::{self, Decodable, Encodable}; +use rustc_span::{Span, DUMMY_SP}; +use smallvec::SmallVec; + +use core::intrinsics; +use std::cmp::Ordering; +use std::fmt; +use std::marker::PhantomData; +use std::mem; +use std::num::NonZeroUsize; + +/// An entity in the Rust type system, which can be one of +/// several kinds (types, lifetimes, and consts). +/// To reduce memory usage, a `GenericArg` is a interned pointer, +/// with the lowest 2 bits being reserved for a tag to +/// indicate the type (`Ty`, `Region`, or `Const`) it points to. +#[derive(Copy, Clone, PartialEq, Eq, Hash)] +pub struct GenericArg<'tcx> { + ptr: NonZeroUsize, + marker: PhantomData<(Ty<'tcx>, ty::Region<'tcx>, &'tcx ty::Const<'tcx>)>, +} + +const TAG_MASK: usize = 0b11; +const TYPE_TAG: usize = 0b00; +const REGION_TAG: usize = 0b01; +const CONST_TAG: usize = 0b10; + +#[derive(Debug, TyEncodable, TyDecodable, PartialEq, Eq, PartialOrd, Ord, HashStable)] +pub enum GenericArgKind<'tcx> { + Lifetime(ty::Region<'tcx>), + Type(Ty<'tcx>), + Const(&'tcx ty::Const<'tcx>), +} + +impl<'tcx> GenericArgKind<'tcx> { + fn pack(self) -> GenericArg<'tcx> { + let (tag, ptr) = match self { + GenericArgKind::Lifetime(lt) => { + // Ensure we can use the tag bits. + assert_eq!(mem::align_of_val(lt) & TAG_MASK, 0); + (REGION_TAG, lt as *const _ as usize) + } + GenericArgKind::Type(ty) => { + // Ensure we can use the tag bits. + assert_eq!(mem::align_of_val(ty) & TAG_MASK, 0); + (TYPE_TAG, ty as *const _ as usize) + } + GenericArgKind::Const(ct) => { + // Ensure we can use the tag bits. + assert_eq!(mem::align_of_val(ct) & TAG_MASK, 0); + (CONST_TAG, ct as *const _ as usize) + } + }; + + GenericArg { ptr: unsafe { NonZeroUsize::new_unchecked(ptr | tag) }, marker: PhantomData } + } +} + +impl fmt::Debug for GenericArg<'tcx> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self.unpack() { + GenericArgKind::Lifetime(lt) => lt.fmt(f), + GenericArgKind::Type(ty) => ty.fmt(f), + GenericArgKind::Const(ct) => ct.fmt(f), + } + } +} + +impl<'tcx> Ord for GenericArg<'tcx> { + fn cmp(&self, other: &GenericArg<'_>) -> Ordering { + self.unpack().cmp(&other.unpack()) + } +} + +impl<'tcx> PartialOrd for GenericArg<'tcx> { + fn partial_cmp(&self, other: &GenericArg<'_>) -> Option<Ordering> { + Some(self.cmp(&other)) + } +} + +impl<'tcx> From<ty::Region<'tcx>> for GenericArg<'tcx> { + fn from(r: ty::Region<'tcx>) -> GenericArg<'tcx> { + GenericArgKind::Lifetime(r).pack() + } +} + +impl<'tcx> From<Ty<'tcx>> for GenericArg<'tcx> { + fn from(ty: Ty<'tcx>) -> GenericArg<'tcx> { + GenericArgKind::Type(ty).pack() + } +} + +impl<'tcx> From<&'tcx ty::Const<'tcx>> for GenericArg<'tcx> { + fn from(c: &'tcx ty::Const<'tcx>) -> GenericArg<'tcx> { + GenericArgKind::Const(c).pack() + } +} + +impl<'tcx> GenericArg<'tcx> { + #[inline] + pub fn unpack(self) -> GenericArgKind<'tcx> { + let ptr = self.ptr.get(); + unsafe { + match ptr & TAG_MASK { + REGION_TAG => GenericArgKind::Lifetime(&*((ptr & !TAG_MASK) as *const _)), + TYPE_TAG => GenericArgKind::Type(&*((ptr & !TAG_MASK) as *const _)), + CONST_TAG => GenericArgKind::Const(&*((ptr & !TAG_MASK) as *const _)), + _ => intrinsics::unreachable(), + } + } + } + + /// Unpack the `GenericArg` as a type when it is known certainly to be a type. + /// This is true in cases where `Substs` is used in places where the kinds are known + /// to be limited (e.g. in tuples, where the only parameters are type parameters). + pub fn expect_ty(self) -> Ty<'tcx> { + match self.unpack() { + GenericArgKind::Type(ty) => ty, + _ => bug!("expected a type, but found another kind"), + } + } + + /// Unpack the `GenericArg` as a const when it is known certainly to be a const. + pub fn expect_const(self) -> &'tcx ty::Const<'tcx> { + match self.unpack() { + GenericArgKind::Const(c) => c, + _ => bug!("expected a const, but found another kind"), + } + } +} + +impl<'a, 'tcx> Lift<'tcx> for GenericArg<'a> { + type Lifted = GenericArg<'tcx>; + + fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { + match self.unpack() { + GenericArgKind::Lifetime(lt) => tcx.lift(<).map(|lt| lt.into()), + GenericArgKind::Type(ty) => tcx.lift(&ty).map(|ty| ty.into()), + GenericArgKind::Const(ct) => tcx.lift(&ct).map(|ct| ct.into()), + } + } +} + +impl<'tcx> TypeFoldable<'tcx> for GenericArg<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + match self.unpack() { + GenericArgKind::Lifetime(lt) => lt.fold_with(folder).into(), + GenericArgKind::Type(ty) => ty.fold_with(folder).into(), + GenericArgKind::Const(ct) => ct.fold_with(folder).into(), + } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + match self.unpack() { + GenericArgKind::Lifetime(lt) => lt.visit_with(visitor), + GenericArgKind::Type(ty) => ty.visit_with(visitor), + GenericArgKind::Const(ct) => ct.visit_with(visitor), + } + } +} + +impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for GenericArg<'tcx> { + fn encode(&self, e: &mut E) -> Result<(), E::Error> { + self.unpack().encode(e) + } +} + +impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for GenericArg<'tcx> { + fn decode(d: &mut D) -> Result<GenericArg<'tcx>, D::Error> { + Ok(GenericArgKind::decode(d)?.pack()) + } +} + +/// A substitution mapping generic parameters to new values. +pub type InternalSubsts<'tcx> = List<GenericArg<'tcx>>; + +pub type SubstsRef<'tcx> = &'tcx InternalSubsts<'tcx>; + +impl<'a, 'tcx> InternalSubsts<'tcx> { + /// Interpret these substitutions as the substitutions of a closure type. + /// Closure substitutions have a particular structure controlled by the + /// compiler that encodes information like the signature and closure kind; + /// see `ty::ClosureSubsts` struct for more comments. + pub fn as_closure(&'a self) -> ClosureSubsts<'a> { + ClosureSubsts { substs: self } + } + + /// Interpret these substitutions as the substitutions of a generator type. + /// Closure substitutions have a particular structure controlled by the + /// compiler that encodes information like the signature and generator kind; + /// see `ty::GeneratorSubsts` struct for more comments. + pub fn as_generator(&'tcx self) -> GeneratorSubsts<'tcx> { + GeneratorSubsts { substs: self } + } + + /// Creates a `InternalSubsts` that maps each generic parameter to itself. + pub fn identity_for_item(tcx: TyCtxt<'tcx>, def_id: DefId) -> SubstsRef<'tcx> { + Self::for_item(tcx, def_id, |param, _| tcx.mk_param_from_def(param)) + } + + /// Creates a `InternalSubsts` for generic parameter definitions, + /// by calling closures to obtain each kind. + /// The closures get to observe the `InternalSubsts` as they're + /// being built, which can be used to correctly + /// substitute defaults of generic parameters. + pub fn for_item<F>(tcx: TyCtxt<'tcx>, def_id: DefId, mut mk_kind: F) -> SubstsRef<'tcx> + where + F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>, + { + let defs = tcx.generics_of(def_id); + let count = defs.count(); + let mut substs = SmallVec::with_capacity(count); + Self::fill_item(&mut substs, tcx, defs, &mut mk_kind); + tcx.intern_substs(&substs) + } + + pub fn extend_to<F>(&self, tcx: TyCtxt<'tcx>, def_id: DefId, mut mk_kind: F) -> SubstsRef<'tcx> + where + F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>, + { + Self::for_item(tcx, def_id, |param, substs| { + self.get(param.index as usize).cloned().unwrap_or_else(|| mk_kind(param, substs)) + }) + } + + fn fill_item<F>( + substs: &mut SmallVec<[GenericArg<'tcx>; 8]>, + tcx: TyCtxt<'tcx>, + defs: &ty::Generics, + mk_kind: &mut F, + ) where + F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>, + { + if let Some(def_id) = defs.parent { + let parent_defs = tcx.generics_of(def_id); + Self::fill_item(substs, tcx, parent_defs, mk_kind); + } + Self::fill_single(substs, defs, mk_kind) + } + + fn fill_single<F>( + substs: &mut SmallVec<[GenericArg<'tcx>; 8]>, + defs: &ty::Generics, + mk_kind: &mut F, + ) where + F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>, + { + substs.reserve(defs.params.len()); + for param in &defs.params { + let kind = mk_kind(param, substs); + assert_eq!(param.index as usize, substs.len()); + substs.push(kind); + } + } + + pub fn is_noop(&self) -> bool { + self.is_empty() + } + + #[inline] + pub fn types(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a { + self.iter() + .filter_map(|k| if let GenericArgKind::Type(ty) = k.unpack() { Some(ty) } else { None }) + } + + #[inline] + pub fn regions(&'a self) -> impl DoubleEndedIterator<Item = ty::Region<'tcx>> + 'a { + self.iter().filter_map(|k| { + if let GenericArgKind::Lifetime(lt) = k.unpack() { Some(lt) } else { None } + }) + } + + #[inline] + pub fn consts(&'a self) -> impl DoubleEndedIterator<Item = &'tcx ty::Const<'tcx>> + 'a { + self.iter().filter_map(|k| { + if let GenericArgKind::Const(ct) = k.unpack() { Some(ct) } else { None } + }) + } + + #[inline] + pub fn non_erasable_generics( + &'a self, + ) -> impl DoubleEndedIterator<Item = GenericArgKind<'tcx>> + 'a { + self.iter().filter_map(|k| match k.unpack() { + GenericArgKind::Lifetime(_) => None, + generic => Some(generic), + }) + } + + #[inline] + pub fn type_at(&self, i: usize) -> Ty<'tcx> { + if let GenericArgKind::Type(ty) = self[i].unpack() { + ty + } else { + bug!("expected type for param #{} in {:?}", i, self); + } + } + + #[inline] + pub fn region_at(&self, i: usize) -> ty::Region<'tcx> { + if let GenericArgKind::Lifetime(lt) = self[i].unpack() { + lt + } else { + bug!("expected region for param #{} in {:?}", i, self); + } + } + + #[inline] + pub fn const_at(&self, i: usize) -> &'tcx ty::Const<'tcx> { + if let GenericArgKind::Const(ct) = self[i].unpack() { + ct + } else { + bug!("expected const for param #{} in {:?}", i, self); + } + } + + #[inline] + pub fn type_for_def(&self, def: &ty::GenericParamDef) -> GenericArg<'tcx> { + self.type_at(def.index as usize).into() + } + + /// Transform from substitutions for a child of `source_ancestor` + /// (e.g., a trait or impl) to substitutions for the same child + /// in a different item, with `target_substs` as the base for + /// the target impl/trait, with the source child-specific + /// parameters (e.g., method parameters) on top of that base. + /// + /// For example given: + /// + /// ```no_run + /// trait X<S> { fn f<T>(); } + /// impl<U> X<U> for U { fn f<V>() {} } + /// ``` + /// + /// * If `self` is `[Self, S, T]`: the identity substs of `f` in the trait. + /// * If `source_ancestor` is the def_id of the trait. + /// * If `target_substs` is `[U]`, the substs for the impl. + /// * Then we will return `[U, T]`, the subst for `f` in the impl that + /// are needed for it to match the trait. + pub fn rebase_onto( + &self, + tcx: TyCtxt<'tcx>, + source_ancestor: DefId, + target_substs: SubstsRef<'tcx>, + ) -> SubstsRef<'tcx> { + let defs = tcx.generics_of(source_ancestor); + tcx.mk_substs(target_substs.iter().chain(self.iter().skip(defs.params.len()))) + } + + pub fn truncate_to(&self, tcx: TyCtxt<'tcx>, generics: &ty::Generics) -> SubstsRef<'tcx> { + tcx.mk_substs(self.iter().take(generics.count())) + } +} + +impl<'tcx> TypeFoldable<'tcx> for SubstsRef<'tcx> { + fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self { + // This code is hot enough that it's worth specializing for the most + // common length lists, to avoid the overhead of `SmallVec` creation. + // The match arms are in order of frequency. The 1, 2, and 0 cases are + // typically hit in 90--99.99% of cases. When folding doesn't change + // the substs, it's faster to reuse the existing substs rather than + // calling `intern_substs`. + match self.len() { + 1 => { + let param0 = self[0].fold_with(folder); + if param0 == self[0] { self } else { folder.tcx().intern_substs(&[param0]) } + } + 2 => { + let param0 = self[0].fold_with(folder); + let param1 = self[1].fold_with(folder); + if param0 == self[0] && param1 == self[1] { + self + } else { + folder.tcx().intern_substs(&[param0, param1]) + } + } + 0 => self, + _ => { + let params: SmallVec<[_; 8]> = self.iter().map(|k| k.fold_with(folder)).collect(); + if params[..] == self[..] { self } else { folder.tcx().intern_substs(¶ms) } + } + } + } + + fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool { + self.iter().any(|t| t.visit_with(visitor)) + } +} + +/////////////////////////////////////////////////////////////////////////// +// Public trait `Subst` +// +// Just call `foo.subst(tcx, substs)` to perform a substitution across +// `foo`. Or use `foo.subst_spanned(tcx, substs, Some(span))` when +// there is more information available (for better errors). + +pub trait Subst<'tcx>: Sized { + fn subst(&self, tcx: TyCtxt<'tcx>, substs: &[GenericArg<'tcx>]) -> Self { + self.subst_spanned(tcx, substs, None) + } + + fn subst_spanned( + &self, + tcx: TyCtxt<'tcx>, + substs: &[GenericArg<'tcx>], + span: Option<Span>, + ) -> Self; +} + +impl<'tcx, T: TypeFoldable<'tcx>> Subst<'tcx> for T { + fn subst_spanned( + &self, + tcx: TyCtxt<'tcx>, + substs: &[GenericArg<'tcx>], + span: Option<Span>, + ) -> T { + let mut folder = SubstFolder { tcx, substs, span, binders_passed: 0 }; + (*self).fold_with(&mut folder) + } +} + +/////////////////////////////////////////////////////////////////////////// +// The actual substitution engine itself is a type folder. + +struct SubstFolder<'a, 'tcx> { + tcx: TyCtxt<'tcx>, + substs: &'a [GenericArg<'tcx>], + + /// The location for which the substitution is performed, if available. + span: Option<Span>, + + /// Number of region binders we have passed through while doing the substitution + binders_passed: u32, +} + +impl<'a, 'tcx> TypeFolder<'tcx> for SubstFolder<'a, 'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &ty::Binder<T>) -> ty::Binder<T> { + self.binders_passed += 1; + let t = t.super_fold_with(self); + self.binders_passed -= 1; + t + } + + fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { + // Note: This routine only handles regions that are bound on + // type declarations and other outer declarations, not those + // bound in *fn types*. Region substitution of the bound + // regions that appear in a function signature is done using + // the specialized routine `ty::replace_late_regions()`. + match *r { + ty::ReEarlyBound(data) => { + let rk = self.substs.get(data.index as usize).map(|k| k.unpack()); + match rk { + Some(GenericArgKind::Lifetime(lt)) => self.shift_region_through_binders(lt), + _ => { + let span = self.span.unwrap_or(DUMMY_SP); + let msg = format!( + "Region parameter out of range \ + when substituting in region {} (index={})", + data.name, data.index + ); + span_bug!(span, "{}", msg); + } + } + } + _ => r, + } + } + + fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { + if !t.needs_subst() { + return t; + } + + match t.kind { + ty::Param(p) => self.ty_for_param(p, t), + _ => t.super_fold_with(self), + } + } + + fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { + if !c.needs_subst() { + return c; + } + + if let ty::ConstKind::Param(p) = c.val { + self.const_for_param(p, c) + } else { + c.super_fold_with(self) + } + } +} + +impl<'a, 'tcx> SubstFolder<'a, 'tcx> { + fn ty_for_param(&self, p: ty::ParamTy, source_ty: Ty<'tcx>) -> Ty<'tcx> { + // Look up the type in the substitutions. It really should be in there. + let opt_ty = self.substs.get(p.index as usize).map(|k| k.unpack()); + let ty = match opt_ty { + Some(GenericArgKind::Type(ty)) => ty, + Some(kind) => { + let span = self.span.unwrap_or(DUMMY_SP); + span_bug!( + span, + "expected type for `{:?}` ({:?}/{}) but found {:?} \ + when substituting, substs={:?}", + p, + source_ty, + p.index, + kind, + self.substs, + ); + } + None => { + let span = self.span.unwrap_or(DUMMY_SP); + span_bug!( + span, + "type parameter `{:?}` ({:?}/{}) out of range \ + when substituting, substs={:?}", + p, + source_ty, + p.index, + self.substs, + ); + } + }; + + self.shift_vars_through_binders(ty) + } + + fn const_for_param( + &self, + p: ParamConst, + source_ct: &'tcx ty::Const<'tcx>, + ) -> &'tcx ty::Const<'tcx> { + // Look up the const in the substitutions. It really should be in there. + let opt_ct = self.substs.get(p.index as usize).map(|k| k.unpack()); + let ct = match opt_ct { + Some(GenericArgKind::Const(ct)) => ct, + Some(kind) => { + let span = self.span.unwrap_or(DUMMY_SP); + span_bug!( + span, + "expected const for `{:?}` ({:?}/{}) but found {:?} \ + when substituting substs={:?}", + p, + source_ct, + p.index, + kind, + self.substs, + ); + } + None => { + let span = self.span.unwrap_or(DUMMY_SP); + span_bug!( + span, + "const parameter `{:?}` ({:?}/{}) out of range \ + when substituting substs={:?}", + p, + source_ct, + p.index, + self.substs, + ); + } + }; + + self.shift_vars_through_binders(ct) + } + + /// It is sometimes necessary to adjust the De Bruijn indices during substitution. This occurs + /// when we are substituting a type with escaping bound vars into a context where we have + /// passed through binders. That's quite a mouthful. Let's see an example: + /// + /// ``` + /// type Func<A> = fn(A); + /// type MetaFunc = for<'a> fn(Func<&'a i32>) + /// ``` + /// + /// The type `MetaFunc`, when fully expanded, will be + /// + /// for<'a> fn(fn(&'a i32)) + /// ^~ ^~ ^~~ + /// | | | + /// | | DebruijnIndex of 2 + /// Binders + /// + /// Here the `'a` lifetime is bound in the outer function, but appears as an argument of the + /// inner one. Therefore, that appearance will have a DebruijnIndex of 2, because we must skip + /// over the inner binder (remember that we count De Bruijn indices from 1). However, in the + /// definition of `MetaFunc`, the binder is not visible, so the type `&'a i32` will have a + /// De Bruijn index of 1. It's only during the substitution that we can see we must increase the + /// depth by 1 to account for the binder that we passed through. + /// + /// As a second example, consider this twist: + /// + /// ``` + /// type FuncTuple<A> = (A,fn(A)); + /// type MetaFuncTuple = for<'a> fn(FuncTuple<&'a i32>) + /// ``` + /// + /// Here the final type will be: + /// + /// for<'a> fn((&'a i32, fn(&'a i32))) + /// ^~~ ^~~ + /// | | + /// DebruijnIndex of 1 | + /// DebruijnIndex of 2 + /// + /// As indicated in the diagram, here the same type `&'a i32` is substituted once, but in the + /// first case we do not increase the De Bruijn index and in the second case we do. The reason + /// is that only in the second case have we passed through a fn binder. + fn shift_vars_through_binders<T: TypeFoldable<'tcx>>(&self, val: T) -> T { + debug!( + "shift_vars(val={:?}, binders_passed={:?}, has_escaping_bound_vars={:?})", + val, + self.binders_passed, + val.has_escaping_bound_vars() + ); + + if self.binders_passed == 0 || !val.has_escaping_bound_vars() { + return val; + } + + let result = ty::fold::shift_vars(self.tcx(), &val, self.binders_passed); + debug!("shift_vars: shifted result = {:?}", result); + + result + } + + fn shift_region_through_binders(&self, region: ty::Region<'tcx>) -> ty::Region<'tcx> { + if self.binders_passed == 0 || !region.has_escaping_bound_vars() { + return region; + } + ty::fold::shift_region(self.tcx, region, self.binders_passed) + } +} + +pub type CanonicalUserSubsts<'tcx> = Canonical<'tcx, UserSubsts<'tcx>>; + +/// Stores the user-given substs to reach some fully qualified path +/// (e.g., `<T>::Item` or `<T as Trait>::Item`). +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable, Lift)] +pub struct UserSubsts<'tcx> { + /// The substitutions for the item as given by the user. + pub substs: SubstsRef<'tcx>, + + /// The self type, in the case of a `<T>::Item` path (when applied + /// to an inherent impl). See `UserSelfTy` below. + pub user_self_ty: Option<UserSelfTy<'tcx>>, +} + +/// Specifies the user-given self type. In the case of a path that +/// refers to a member in an inherent impl, this self type is +/// sometimes needed to constrain the type parameters on the impl. For +/// example, in this code: +/// +/// ``` +/// struct Foo<T> { } +/// impl<A> Foo<A> { fn method() { } } +/// ``` +/// +/// when you then have a path like `<Foo<&'static u32>>::method`, +/// this struct would carry the `DefId` of the impl along with the +/// self type `Foo<u32>`. Then we can instantiate the parameters of +/// the impl (with the substs from `UserSubsts`) and apply those to +/// the self type, giving `Foo<?A>`. Finally, we unify that with +/// the self type here, which contains `?A` to be `&'static u32` +#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] +#[derive(HashStable, TypeFoldable, Lift)] +pub struct UserSelfTy<'tcx> { + pub impl_def_id: DefId, + pub self_ty: Ty<'tcx>, +} diff --git a/compiler/rustc_middle/src/ty/trait_def.rs b/compiler/rustc_middle/src/ty/trait_def.rs new file mode 100644 index 00000000000..86fe3ac3751 --- /dev/null +++ b/compiler/rustc_middle/src/ty/trait_def.rs @@ -0,0 +1,234 @@ +use crate::ich::{self, StableHashingContext}; +use crate::traits::specialization_graph; +use crate::ty::fast_reject; +use crate::ty::fold::TypeFoldable; +use crate::ty::{Ty, TyCtxt}; +use rustc_hir as hir; +use rustc_hir::def_id::{CrateNum, DefId}; +use rustc_hir::definitions::DefPathHash; +use rustc_hir::HirId; + +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_errors::ErrorReported; +use rustc_macros::HashStable; +use std::collections::BTreeMap; + +/// A trait's definition with type information. +#[derive(HashStable)] +pub struct TraitDef { + // We already have the def_path_hash below, no need to hash it twice + #[stable_hasher(ignore)] + pub def_id: DefId, + + pub unsafety: hir::Unsafety, + + /// If `true`, then this trait had the `#[rustc_paren_sugar]` + /// attribute, indicating that it should be used with `Foo()` + /// sugar. This is a temporary thing -- eventually any trait will + /// be usable with the sugar (or without it). + pub paren_sugar: bool, + + pub has_auto_impl: bool, + + /// If `true`, then this trait has the `#[marker]` attribute, indicating + /// that all its associated items have defaults that cannot be overridden, + /// and thus `impl`s of it are allowed to overlap. + pub is_marker: bool, + + /// Used to determine whether the standard library is allowed to specialize + /// on this trait. + pub specialization_kind: TraitSpecializationKind, + + /// The ICH of this trait's DefPath, cached here so it doesn't have to be + /// recomputed all the time. + pub def_path_hash: DefPathHash, +} + +/// Whether this trait is treated specially by the standard library +/// specialization lint. +#[derive(HashStable, PartialEq, Clone, Copy, TyEncodable, TyDecodable)] +pub enum TraitSpecializationKind { + /// The default. Specializing on this trait is not allowed. + None, + /// Specializing on this trait is allowed because it doesn't have any + /// methods. For example `Sized` or `FusedIterator`. + /// Applies to traits with the `rustc_unsafe_specialization_marker` + /// attribute. + Marker, + /// Specializing on this trait is allowed because all of the impls of this + /// trait are "always applicable". Always applicable means that if + /// `X<'x>: T<'y>` for any lifetimes, then `for<'a, 'b> X<'a>: T<'b>`. + /// Applies to traits with the `rustc_specialization_trait` attribute. + AlwaysApplicable, +} + +#[derive(Default)] +pub struct TraitImpls { + blanket_impls: Vec<DefId>, + /// Impls indexed by their simplified self type, for fast lookup. + non_blanket_impls: FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>, +} + +impl<'tcx> TraitDef { + pub fn new( + def_id: DefId, + unsafety: hir::Unsafety, + paren_sugar: bool, + has_auto_impl: bool, + is_marker: bool, + specialization_kind: TraitSpecializationKind, + def_path_hash: DefPathHash, + ) -> TraitDef { + TraitDef { + def_id, + unsafety, + paren_sugar, + has_auto_impl, + is_marker, + specialization_kind, + def_path_hash, + } + } + + pub fn ancestors( + &self, + tcx: TyCtxt<'tcx>, + of_impl: DefId, + ) -> Result<specialization_graph::Ancestors<'tcx>, ErrorReported> { + specialization_graph::ancestors(tcx, self.def_id, of_impl) + } +} + +impl<'tcx> TyCtxt<'tcx> { + pub fn for_each_impl<F: FnMut(DefId)>(self, def_id: DefId, mut f: F) { + let impls = self.trait_impls_of(def_id); + + for &impl_def_id in impls.blanket_impls.iter() { + f(impl_def_id); + } + + for v in impls.non_blanket_impls.values() { + for &impl_def_id in v { + f(impl_def_id); + } + } + } + + /// Iterate over every impl that could possibly match the + /// self type `self_ty`. + pub fn for_each_relevant_impl<F: FnMut(DefId)>( + self, + def_id: DefId, + self_ty: Ty<'tcx>, + mut f: F, + ) { + let impls = self.trait_impls_of(def_id); + + for &impl_def_id in impls.blanket_impls.iter() { + f(impl_def_id); + } + + // simplify_type(.., false) basically replaces type parameters and + // projections with infer-variables. This is, of course, done on + // the impl trait-ref when it is instantiated, but not on the + // predicate trait-ref which is passed here. + // + // for example, if we match `S: Copy` against an impl like + // `impl<T:Copy> Copy for Option<T>`, we replace the type variable + // in `Option<T>` with an infer variable, to `Option<_>` (this + // doesn't actually change fast_reject output), but we don't + // replace `S` with anything - this impl of course can't be + // selected, and as there are hundreds of similar impls, + // considering them would significantly harm performance. + + // This depends on the set of all impls for the trait. That is + // unfortunate. When we get red-green recompilation, we would like + // to have a way of knowing whether the set of relevant impls + // changed. The most naive + // way would be to compute the Vec of relevant impls and see whether + // it differs between compilations. That shouldn't be too slow by + // itself - we do quite a bit of work for each relevant impl anyway. + // + // If we want to be faster, we could have separate queries for + // blanket and non-blanket impls, and compare them separately. + // + // I think we'll cross that bridge when we get to it. + if let Some(simp) = fast_reject::simplify_type(self, self_ty, true) { + if let Some(impls) = impls.non_blanket_impls.get(&simp) { + for &impl_def_id in impls { + f(impl_def_id); + } + } + } else { + for &impl_def_id in impls.non_blanket_impls.values().flatten() { + f(impl_def_id); + } + } + } + + /// Returns a vector containing all impls + pub fn all_impls(self, def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx { + let TraitImpls { blanket_impls, non_blanket_impls } = self.trait_impls_of(def_id); + + blanket_impls.iter().chain(non_blanket_impls.iter().map(|(_, v)| v).flatten()).cloned() + } +} + +// Query provider for `all_local_trait_impls`. +pub(super) fn all_local_trait_impls<'tcx>( + tcx: TyCtxt<'tcx>, + krate: CrateNum, +) -> &'tcx BTreeMap<DefId, Vec<HirId>> { + &tcx.hir_crate(krate).trait_impls +} + +// Query provider for `trait_impls_of`. +pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> TraitImpls { + let mut impls = TraitImpls::default(); + + // Traits defined in the current crate can't have impls in upstream + // crates, so we don't bother querying the cstore. + if !trait_id.is_local() { + for &cnum in tcx.crates().iter() { + for &(impl_def_id, simplified_self_ty) in + tcx.implementations_of_trait((cnum, trait_id)).iter() + { + if let Some(simplified_self_ty) = simplified_self_ty { + impls + .non_blanket_impls + .entry(simplified_self_ty) + .or_default() + .push(impl_def_id); + } else { + impls.blanket_impls.push(impl_def_id); + } + } + } + } + + for &hir_id in tcx.hir().trait_impls(trait_id) { + let impl_def_id = tcx.hir().local_def_id(hir_id).to_def_id(); + + let impl_self_ty = tcx.type_of(impl_def_id); + if impl_self_ty.references_error() { + continue; + } + + if let Some(simplified_self_ty) = fast_reject::simplify_type(tcx, impl_self_ty, false) { + impls.non_blanket_impls.entry(simplified_self_ty).or_default().push(impl_def_id); + } else { + impls.blanket_impls.push(impl_def_id); + } + } + + impls +} + +impl<'a> HashStable<StableHashingContext<'a>> for TraitImpls { + fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { + let TraitImpls { ref blanket_impls, ref non_blanket_impls } = *self; + + ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, non_blanket_impls); + } +} diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs new file mode 100644 index 00000000000..63d4dcca080 --- /dev/null +++ b/compiler/rustc_middle/src/ty/util.rs @@ -0,0 +1,1168 @@ +//! Miscellaneous type-system utilities that are too small to deserve their own modules. + +use crate::ich::NodeIdHashingMode; +use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; +use crate::mir::interpret::{sign_extend, truncate}; +use crate::ty::fold::TypeFolder; +use crate::ty::layout::IntegerExt; +use crate::ty::query::TyCtxtAt; +use crate::ty::subst::{GenericArgKind, InternalSubsts, Subst, SubstsRef}; +use crate::ty::TyKind::*; +use crate::ty::{self, DefIdTree, GenericParamDefKind, List, Ty, TyCtxt, TypeFoldable}; +use rustc_apfloat::Float as _; +use rustc_ast as ast; +use rustc_attr::{self as attr, SignedInt, UnsignedInt}; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_errors::ErrorReported; +use rustc_hir as hir; +use rustc_hir::def::DefKind; +use rustc_hir::def_id::DefId; +use rustc_macros::HashStable; +use rustc_span::Span; +use rustc_target::abi::{Integer, Size, TargetDataLayout}; +use smallvec::SmallVec; +use std::{cmp, fmt}; + +#[derive(Copy, Clone, Debug)] +pub struct Discr<'tcx> { + /// Bit representation of the discriminant (e.g., `-128i8` is `0xFF_u128`). + pub val: u128, + pub ty: Ty<'tcx>, +} + +impl<'tcx> fmt::Display for Discr<'tcx> { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + match self.ty.kind { + ty::Int(ity) => { + let size = ty::tls::with(|tcx| Integer::from_attr(&tcx, SignedInt(ity)).size()); + let x = self.val; + // sign extend the raw representation to be an i128 + let x = sign_extend(x, size) as i128; + write!(fmt, "{}", x) + } + _ => write!(fmt, "{}", self.val), + } + } +} + +fn signed_min(size: Size) -> i128 { + sign_extend(1_u128 << (size.bits() - 1), size) as i128 +} + +fn signed_max(size: Size) -> i128 { + i128::MAX >> (128 - size.bits()) +} + +fn unsigned_max(size: Size) -> u128 { + u128::MAX >> (128 - size.bits()) +} + +fn int_size_and_signed<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> (Size, bool) { + let (int, signed) = match ty.kind { + Int(ity) => (Integer::from_attr(&tcx, SignedInt(ity)), true), + Uint(uty) => (Integer::from_attr(&tcx, UnsignedInt(uty)), false), + _ => bug!("non integer discriminant"), + }; + (int.size(), signed) +} + +impl<'tcx> Discr<'tcx> { + /// Adds `1` to the value and wraps around if the maximum for the type is reached. + pub fn wrap_incr(self, tcx: TyCtxt<'tcx>) -> Self { + self.checked_add(tcx, 1).0 + } + pub fn checked_add(self, tcx: TyCtxt<'tcx>, n: u128) -> (Self, bool) { + let (size, signed) = int_size_and_signed(tcx, self.ty); + let (val, oflo) = if signed { + let min = signed_min(size); + let max = signed_max(size); + let val = sign_extend(self.val, size) as i128; + assert!(n < (i128::MAX as u128)); + let n = n as i128; + let oflo = val > max - n; + let val = if oflo { min + (n - (max - val) - 1) } else { val + n }; + // zero the upper bits + let val = val as u128; + let val = truncate(val, size); + (val, oflo) + } else { + let max = unsigned_max(size); + let val = self.val; + let oflo = val > max - n; + let val = if oflo { n - (max - val) - 1 } else { val + n }; + (val, oflo) + }; + (Self { val, ty: self.ty }, oflo) + } +} + +pub trait IntTypeExt { + fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx>; + fn disr_incr<'tcx>(&self, tcx: TyCtxt<'tcx>, val: Option<Discr<'tcx>>) -> Option<Discr<'tcx>>; + fn initial_discriminant<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Discr<'tcx>; +} + +impl IntTypeExt for attr::IntType { + fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { + match *self { + SignedInt(ast::IntTy::I8) => tcx.types.i8, + SignedInt(ast::IntTy::I16) => tcx.types.i16, + SignedInt(ast::IntTy::I32) => tcx.types.i32, + SignedInt(ast::IntTy::I64) => tcx.types.i64, + SignedInt(ast::IntTy::I128) => tcx.types.i128, + SignedInt(ast::IntTy::Isize) => tcx.types.isize, + UnsignedInt(ast::UintTy::U8) => tcx.types.u8, + UnsignedInt(ast::UintTy::U16) => tcx.types.u16, + UnsignedInt(ast::UintTy::U32) => tcx.types.u32, + UnsignedInt(ast::UintTy::U64) => tcx.types.u64, + UnsignedInt(ast::UintTy::U128) => tcx.types.u128, + UnsignedInt(ast::UintTy::Usize) => tcx.types.usize, + } + } + + fn initial_discriminant<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Discr<'tcx> { + Discr { val: 0, ty: self.to_ty(tcx) } + } + + fn disr_incr<'tcx>(&self, tcx: TyCtxt<'tcx>, val: Option<Discr<'tcx>>) -> Option<Discr<'tcx>> { + if let Some(val) = val { + assert_eq!(self.to_ty(tcx), val.ty); + let (new, oflo) = val.checked_add(tcx, 1); + if oflo { None } else { Some(new) } + } else { + Some(self.initial_discriminant(tcx)) + } + } +} + +/// Describes whether a type is representable. For types that are not +/// representable, 'SelfRecursive' and 'ContainsRecursive' are used to +/// distinguish between types that are recursive with themselves and types that +/// contain a different recursive type. These cases can therefore be treated +/// differently when reporting errors. +/// +/// The ordering of the cases is significant. They are sorted so that cmp::max +/// will keep the "more erroneous" of two values. +#[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)] +pub enum Representability { + Representable, + ContainsRecursive, + SelfRecursive(Vec<Span>), +} + +impl<'tcx> TyCtxt<'tcx> { + /// Creates a hash of the type `Ty` which will be the same no matter what crate + /// context it's calculated within. This is used by the `type_id` intrinsic. + pub fn type_id_hash(self, ty: Ty<'tcx>) -> u64 { + let mut hasher = StableHasher::new(); + let mut hcx = self.create_stable_hashing_context(); + + // We want the type_id be independent of the types free regions, so we + // erase them. The erase_regions() call will also anonymize bound + // regions, which is desirable too. + let ty = self.erase_regions(&ty); + + hcx.while_hashing_spans(false, |hcx| { + hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { + ty.hash_stable(hcx, &mut hasher); + }); + }); + hasher.finish() + } +} + +impl<'tcx> TyCtxt<'tcx> { + pub fn has_error_field(self, ty: Ty<'tcx>) -> bool { + if let ty::Adt(def, substs) = ty.kind { + for field in def.all_fields() { + let field_ty = field.ty(self, substs); + if let Error(_) = field_ty.kind { + return true; + } + } + } + false + } + + /// Attempts to returns the deeply last field of nested structures, but + /// does not apply any normalization in its search. Returns the same type + /// if input `ty` is not a structure at all. + pub fn struct_tail_without_normalization(self, ty: Ty<'tcx>) -> Ty<'tcx> { + let tcx = self; + tcx.struct_tail_with_normalize(ty, |ty| ty) + } + + /// Returns the deeply last field of nested structures, or the same type if + /// not a structure at all. Corresponds to the only possible unsized field, + /// and its type can be used to determine unsizing strategy. + /// + /// Should only be called if `ty` has no inference variables and does not + /// need its lifetimes preserved (e.g. as part of codegen); otherwise + /// normalization attempt may cause compiler bugs. + pub fn struct_tail_erasing_lifetimes( + self, + ty: Ty<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> Ty<'tcx> { + let tcx = self; + tcx.struct_tail_with_normalize(ty, |ty| tcx.normalize_erasing_regions(param_env, ty)) + } + + /// Returns the deeply last field of nested structures, or the same type if + /// not a structure at all. Corresponds to the only possible unsized field, + /// and its type can be used to determine unsizing strategy. + /// + /// This is parameterized over the normalization strategy (i.e. how to + /// handle `<T as Trait>::Assoc` and `impl Trait`); pass the identity + /// function to indicate no normalization should take place. + /// + /// See also `struct_tail_erasing_lifetimes`, which is suitable for use + /// during codegen. + pub fn struct_tail_with_normalize( + self, + mut ty: Ty<'tcx>, + normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>, + ) -> Ty<'tcx> { + loop { + match ty.kind { + ty::Adt(def, substs) => { + if !def.is_struct() { + break; + } + match def.non_enum_variant().fields.last() { + Some(f) => ty = f.ty(self, substs), + None => break, + } + } + + ty::Tuple(tys) => { + if let Some((&last_ty, _)) = tys.split_last() { + ty = last_ty.expect_ty(); + } else { + break; + } + } + + ty::Projection(_) | ty::Opaque(..) => { + let normalized = normalize(ty); + if ty == normalized { + return ty; + } else { + ty = normalized; + } + } + + _ => { + break; + } + } + } + ty + } + + /// Same as applying `struct_tail` on `source` and `target`, but only + /// keeps going as long as the two types are instances of the same + /// structure definitions. + /// For `(Foo<Foo<T>>, Foo<dyn Trait>)`, the result will be `(Foo<T>, Trait)`, + /// whereas struct_tail produces `T`, and `Trait`, respectively. + /// + /// Should only be called if the types have no inference variables and do + /// not need their lifetimes preserved (e.g., as part of codegen); otherwise, + /// normalization attempt may cause compiler bugs. + pub fn struct_lockstep_tails_erasing_lifetimes( + self, + source: Ty<'tcx>, + target: Ty<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> (Ty<'tcx>, Ty<'tcx>) { + let tcx = self; + tcx.struct_lockstep_tails_with_normalize(source, target, |ty| { + tcx.normalize_erasing_regions(param_env, ty) + }) + } + + /// Same as applying `struct_tail` on `source` and `target`, but only + /// keeps going as long as the two types are instances of the same + /// structure definitions. + /// For `(Foo<Foo<T>>, Foo<dyn Trait>)`, the result will be `(Foo<T>, Trait)`, + /// whereas struct_tail produces `T`, and `Trait`, respectively. + /// + /// See also `struct_lockstep_tails_erasing_lifetimes`, which is suitable for use + /// during codegen. + pub fn struct_lockstep_tails_with_normalize( + self, + source: Ty<'tcx>, + target: Ty<'tcx>, + normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>, + ) -> (Ty<'tcx>, Ty<'tcx>) { + let (mut a, mut b) = (source, target); + loop { + match (&a.kind, &b.kind) { + (&Adt(a_def, a_substs), &Adt(b_def, b_substs)) + if a_def == b_def && a_def.is_struct() => + { + if let Some(f) = a_def.non_enum_variant().fields.last() { + a = f.ty(self, a_substs); + b = f.ty(self, b_substs); + } else { + break; + } + } + (&Tuple(a_tys), &Tuple(b_tys)) if a_tys.len() == b_tys.len() => { + if let Some(a_last) = a_tys.last() { + a = a_last.expect_ty(); + b = b_tys.last().unwrap().expect_ty(); + } else { + break; + } + } + (ty::Projection(_) | ty::Opaque(..), _) + | (_, ty::Projection(_) | ty::Opaque(..)) => { + // If either side is a projection, attempt to + // progress via normalization. (Should be safe to + // apply to both sides as normalization is + // idempotent.) + let a_norm = normalize(a); + let b_norm = normalize(b); + if a == a_norm && b == b_norm { + break; + } else { + a = a_norm; + b = b_norm; + } + } + + _ => break, + } + } + (a, b) + } + + /// Calculate the destructor of a given type. + pub fn calculate_dtor( + self, + adt_did: DefId, + validate: &mut dyn FnMut(Self, DefId) -> Result<(), ErrorReported>, + ) -> Option<ty::Destructor> { + let drop_trait = self.lang_items().drop_trait()?; + self.ensure().coherent_trait(drop_trait); + + let mut dtor_did = None; + let ty = self.type_of(adt_did); + self.for_each_relevant_impl(drop_trait, ty, |impl_did| { + if let Some(item) = self.associated_items(impl_did).in_definition_order().next() { + if validate(self, impl_did).is_ok() { + dtor_did = Some(item.def_id); + } + } + }); + + Some(ty::Destructor { did: dtor_did? }) + } + + /// Returns the set of types that are required to be alive in + /// order to run the destructor of `def` (see RFCs 769 and + /// 1238). + /// + /// Note that this returns only the constraints for the + /// destructor of `def` itself. For the destructors of the + /// contents, you need `adt_dtorck_constraint`. + pub fn destructor_constraints(self, def: &'tcx ty::AdtDef) -> Vec<ty::subst::GenericArg<'tcx>> { + let dtor = match def.destructor(self) { + None => { + debug!("destructor_constraints({:?}) - no dtor", def.did); + return vec![]; + } + Some(dtor) => dtor.did, + }; + + let impl_def_id = self.associated_item(dtor).container.id(); + let impl_generics = self.generics_of(impl_def_id); + + // We have a destructor - all the parameters that are not + // pure_wrt_drop (i.e, don't have a #[may_dangle] attribute) + // must be live. + + // We need to return the list of parameters from the ADTs + // generics/substs that correspond to impure parameters on the + // impl's generics. This is a bit ugly, but conceptually simple: + // + // Suppose our ADT looks like the following + // + // struct S<X, Y, Z>(X, Y, Z); + // + // and the impl is + // + // impl<#[may_dangle] P0, P1, P2> Drop for S<P1, P2, P0> + // + // We want to return the parameters (X, Y). For that, we match + // up the item-substs <X, Y, Z> with the substs on the impl ADT, + // <P1, P2, P0>, and then look up which of the impl substs refer to + // parameters marked as pure. + + let impl_substs = match self.type_of(impl_def_id).kind { + ty::Adt(def_, substs) if def_ == def => substs, + _ => bug!(), + }; + + let item_substs = match self.type_of(def.did).kind { + ty::Adt(def_, substs) if def_ == def => substs, + _ => bug!(), + }; + + let result = item_substs + .iter() + .zip(impl_substs.iter()) + .filter(|&(_, k)| { + match k.unpack() { + GenericArgKind::Lifetime(&ty::RegionKind::ReEarlyBound(ref ebr)) => { + !impl_generics.region_param(ebr, self).pure_wrt_drop + } + GenericArgKind::Type(&ty::TyS { kind: ty::Param(ref pt), .. }) => { + !impl_generics.type_param(pt, self).pure_wrt_drop + } + GenericArgKind::Const(&ty::Const { + val: ty::ConstKind::Param(ref pc), .. + }) => !impl_generics.const_param(pc, self).pure_wrt_drop, + GenericArgKind::Lifetime(_) + | GenericArgKind::Type(_) + | GenericArgKind::Const(_) => { + // Not a type, const or region param: this should be reported + // as an error. + false + } + } + }) + .map(|(item_param, _)| item_param) + .collect(); + debug!("destructor_constraint({:?}) = {:?}", def.did, result); + result + } + + /// Returns `true` if `def_id` refers to a closure (e.g., `|x| x * 2`). Note + /// that closures have a `DefId`, but the closure *expression* also + /// has a `HirId` that is located within the context where the + /// closure appears (and, sadly, a corresponding `NodeId`, since + /// those are not yet phased out). The parent of the closure's + /// `DefId` will also be the context where it appears. + pub fn is_closure(self, def_id: DefId) -> bool { + matches!(self.def_kind(def_id), DefKind::Closure | DefKind::Generator) + } + + /// Returns `true` if `def_id` refers to a trait (i.e., `trait Foo { ... }`). + pub fn is_trait(self, def_id: DefId) -> bool { + self.def_kind(def_id) == DefKind::Trait + } + + /// Returns `true` if `def_id` refers to a trait alias (i.e., `trait Foo = ...;`), + /// and `false` otherwise. + pub fn is_trait_alias(self, def_id: DefId) -> bool { + self.def_kind(def_id) == DefKind::TraitAlias + } + + /// Returns `true` if this `DefId` refers to the implicit constructor for + /// a tuple struct like `struct Foo(u32)`, and `false` otherwise. + pub fn is_constructor(self, def_id: DefId) -> bool { + matches!(self.def_kind(def_id), DefKind::Ctor(..)) + } + + /// Given the def-ID of a fn or closure, returns the def-ID of + /// the innermost fn item that the closure is contained within. + /// This is a significant `DefId` because, when we do + /// type-checking, we type-check this fn item and all of its + /// (transitive) closures together. Therefore, when we fetch the + /// `typeck` the closure, for example, we really wind up + /// fetching the `typeck` the enclosing fn item. + pub fn closure_base_def_id(self, def_id: DefId) -> DefId { + let mut def_id = def_id; + while self.is_closure(def_id) { + def_id = self.parent(def_id).unwrap_or_else(|| { + bug!("closure {:?} has no parent", def_id); + }); + } + def_id + } + + /// Given the `DefId` and substs a closure, creates the type of + /// `self` argument that the closure expects. For example, for a + /// `Fn` closure, this would return a reference type `&T` where + /// `T = closure_ty`. + /// + /// Returns `None` if this closure's kind has not yet been inferred. + /// This should only be possible during type checking. + /// + /// Note that the return value is a late-bound region and hence + /// wrapped in a binder. + pub fn closure_env_ty( + self, + closure_def_id: DefId, + closure_substs: SubstsRef<'tcx>, + ) -> Option<ty::Binder<Ty<'tcx>>> { + let closure_ty = self.mk_closure(closure_def_id, closure_substs); + let env_region = ty::ReLateBound(ty::INNERMOST, ty::BrEnv); + let closure_kind_ty = closure_substs.as_closure().kind_ty(); + let closure_kind = closure_kind_ty.to_opt_closure_kind()?; + let env_ty = match closure_kind { + ty::ClosureKind::Fn => self.mk_imm_ref(self.mk_region(env_region), closure_ty), + ty::ClosureKind::FnMut => self.mk_mut_ref(self.mk_region(env_region), closure_ty), + ty::ClosureKind::FnOnce => closure_ty, + }; + Some(ty::Binder::bind(env_ty)) + } + + /// Given the `DefId` of some item that has no type or const parameters, make + /// a suitable "empty substs" for it. + pub fn empty_substs_for_def_id(self, item_def_id: DefId) -> SubstsRef<'tcx> { + InternalSubsts::for_item(self, item_def_id, |param, _| match param.kind { + GenericParamDefKind::Lifetime => self.lifetimes.re_erased.into(), + GenericParamDefKind::Type { .. } => { + bug!("empty_substs_for_def_id: {:?} has type parameters", item_def_id) + } + GenericParamDefKind::Const { .. } => { + bug!("empty_substs_for_def_id: {:?} has const parameters", item_def_id) + } + }) + } + + /// Returns `true` if the node pointed to by `def_id` is a `static` item. + pub fn is_static(&self, def_id: DefId) -> bool { + self.static_mutability(def_id).is_some() + } + + /// Returns `true` if this is a `static` item with the `#[thread_local]` attribute. + pub fn is_thread_local_static(&self, def_id: DefId) -> bool { + self.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) + } + + /// Returns `true` if the node pointed to by `def_id` is a mutable `static` item. + pub fn is_mutable_static(&self, def_id: DefId) -> bool { + self.static_mutability(def_id) == Some(hir::Mutability::Mut) + } + + /// Get the type of the pointer to the static that we use in MIR. + pub fn static_ptr_ty(&self, def_id: DefId) -> Ty<'tcx> { + // Make sure that any constants in the static's type are evaluated. + let static_ty = self.normalize_erasing_regions(ty::ParamEnv::empty(), self.type_of(def_id)); + + if self.is_mutable_static(def_id) { + self.mk_mut_ptr(static_ty) + } else { + self.mk_imm_ref(self.lifetimes.re_erased, static_ty) + } + } + + /// Expands the given impl trait type, stopping if the type is recursive. + pub fn try_expand_impl_trait_type( + self, + def_id: DefId, + substs: SubstsRef<'tcx>, + ) -> Result<Ty<'tcx>, Ty<'tcx>> { + let mut visitor = OpaqueTypeExpander { + seen_opaque_tys: FxHashSet::default(), + expanded_cache: FxHashMap::default(), + primary_def_id: Some(def_id), + found_recursion: false, + check_recursion: true, + tcx: self, + }; + + let expanded_type = visitor.expand_opaque_ty(def_id, substs).unwrap(); + if visitor.found_recursion { Err(expanded_type) } else { Ok(expanded_type) } + } +} + +struct OpaqueTypeExpander<'tcx> { + // Contains the DefIds of the opaque types that are currently being + // expanded. When we expand an opaque type we insert the DefId of + // that type, and when we finish expanding that type we remove the + // its DefId. + seen_opaque_tys: FxHashSet<DefId>, + // Cache of all expansions we've seen so far. This is a critical + // optimization for some large types produced by async fn trees. + expanded_cache: FxHashMap<(DefId, SubstsRef<'tcx>), Ty<'tcx>>, + primary_def_id: Option<DefId>, + found_recursion: bool, + /// Whether or not to check for recursive opaque types. + /// This is `true` when we're explicitly checking for opaque type + /// recursion, and 'false' otherwise to avoid unnecessary work. + check_recursion: bool, + tcx: TyCtxt<'tcx>, +} + +impl<'tcx> OpaqueTypeExpander<'tcx> { + fn expand_opaque_ty(&mut self, def_id: DefId, substs: SubstsRef<'tcx>) -> Option<Ty<'tcx>> { + if self.found_recursion { + return None; + } + let substs = substs.fold_with(self); + if !self.check_recursion || self.seen_opaque_tys.insert(def_id) { + let expanded_ty = match self.expanded_cache.get(&(def_id, substs)) { + Some(expanded_ty) => expanded_ty, + None => { + let generic_ty = self.tcx.type_of(def_id); + let concrete_ty = generic_ty.subst(self.tcx, substs); + let expanded_ty = self.fold_ty(concrete_ty); + self.expanded_cache.insert((def_id, substs), expanded_ty); + expanded_ty + } + }; + if self.check_recursion { + self.seen_opaque_tys.remove(&def_id); + } + Some(expanded_ty) + } else { + // If another opaque type that we contain is recursive, then it + // will report the error, so we don't have to. + self.found_recursion = def_id == *self.primary_def_id.as_ref().unwrap(); + None + } + } +} + +impl<'tcx> TypeFolder<'tcx> for OpaqueTypeExpander<'tcx> { + fn tcx(&self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { + if let ty::Opaque(def_id, substs) = t.kind { + self.expand_opaque_ty(def_id, substs).unwrap_or(t) + } else if t.has_opaque_types() { + t.super_fold_with(self) + } else { + t + } + } +} + +impl<'tcx> ty::TyS<'tcx> { + /// Returns the maximum value for the given numeric type (including `char`s) + /// or returns `None` if the type is not numeric. + pub fn numeric_max_val(&'tcx self, tcx: TyCtxt<'tcx>) -> Option<&'tcx ty::Const<'tcx>> { + let val = match self.kind { + ty::Int(_) | ty::Uint(_) => { + let (size, signed) = int_size_and_signed(tcx, self); + let val = if signed { signed_max(size) as u128 } else { unsigned_max(size) }; + Some(val) + } + ty::Char => Some(std::char::MAX as u128), + ty::Float(fty) => Some(match fty { + ast::FloatTy::F32 => ::rustc_apfloat::ieee::Single::INFINITY.to_bits(), + ast::FloatTy::F64 => ::rustc_apfloat::ieee::Double::INFINITY.to_bits(), + }), + _ => None, + }; + val.map(|v| ty::Const::from_bits(tcx, v, ty::ParamEnv::empty().and(self))) + } + + /// Returns the minimum value for the given numeric type (including `char`s) + /// or returns `None` if the type is not numeric. + pub fn numeric_min_val(&'tcx self, tcx: TyCtxt<'tcx>) -> Option<&'tcx ty::Const<'tcx>> { + let val = match self.kind { + ty::Int(_) | ty::Uint(_) => { + let (size, signed) = int_size_and_signed(tcx, self); + let val = if signed { truncate(signed_min(size) as u128, size) } else { 0 }; + Some(val) + } + ty::Char => Some(0), + ty::Float(fty) => Some(match fty { + ast::FloatTy::F32 => (-::rustc_apfloat::ieee::Single::INFINITY).to_bits(), + ast::FloatTy::F64 => (-::rustc_apfloat::ieee::Double::INFINITY).to_bits(), + }), + _ => None, + }; + val.map(|v| ty::Const::from_bits(tcx, v, ty::ParamEnv::empty().and(self))) + } + + /// Checks whether values of this type `T` are *moved* or *copied* + /// when referenced -- this amounts to a check for whether `T: + /// Copy`, but note that we **don't** consider lifetimes when + /// doing this check. This means that we may generate MIR which + /// does copies even when the type actually doesn't satisfy the + /// full requirements for the `Copy` trait (cc #29149) -- this + /// winds up being reported as an error during NLL borrow check. + pub fn is_copy_modulo_regions( + &'tcx self, + tcx_at: TyCtxtAt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> bool { + tcx_at.is_copy_raw(param_env.and(self)) + } + + /// Checks whether values of this type `T` have a size known at + /// compile time (i.e., whether `T: Sized`). Lifetimes are ignored + /// for the purposes of this check, so it can be an + /// over-approximation in generic contexts, where one can have + /// strange rules like `<T as Foo<'static>>::Bar: Sized` that + /// actually carry lifetime requirements. + pub fn is_sized(&'tcx self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { + self.is_trivially_sized(tcx_at.tcx) || tcx_at.is_sized_raw(param_env.and(self)) + } + + /// Checks whether values of this type `T` implement the `Freeze` + /// trait -- frozen types are those that do not contain a + /// `UnsafeCell` anywhere. This is a language concept used to + /// distinguish "true immutability", which is relevant to + /// optimization as well as the rules around static values. Note + /// that the `Freeze` trait is not exposed to end users and is + /// effectively an implementation detail. + // FIXME: use `TyCtxtAt` instead of separate `Span`. + pub fn is_freeze(&'tcx self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { + self.is_trivially_freeze() || tcx_at.is_freeze_raw(param_env.and(self)) + } + + /// Fast path helper for testing if a type is `Freeze`. + /// + /// Returning true means the type is known to be `Freeze`. Returning + /// `false` means nothing -- could be `Freeze`, might not be. + fn is_trivially_freeze(&self) -> bool { + match self.kind { + ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Bool + | ty::Char + | ty::Str + | ty::Never + | ty::Ref(..) + | ty::RawPtr(_) + | ty::FnDef(..) + | ty::Error(_) + | ty::FnPtr(_) => true, + ty::Tuple(_) => self.tuple_fields().all(Self::is_trivially_freeze), + ty::Slice(elem_ty) | ty::Array(elem_ty, _) => elem_ty.is_trivially_freeze(), + ty::Adt(..) + | ty::Bound(..) + | ty::Closure(..) + | ty::Dynamic(..) + | ty::Foreign(_) + | ty::Generator(..) + | ty::GeneratorWitness(_) + | ty::Infer(_) + | ty::Opaque(..) + | ty::Param(_) + | ty::Placeholder(_) + | ty::Projection(_) => false, + } + } + + /// If `ty.needs_drop(...)` returns `true`, then `ty` is definitely + /// non-copy and *might* have a destructor attached; if it returns + /// `false`, then `ty` definitely has no destructor (i.e., no drop glue). + /// + /// (Note that this implies that if `ty` has a destructor attached, + /// then `needs_drop` will definitely return `true` for `ty`.) + /// + /// Note that this method is used to check eligible types in unions. + #[inline] + pub fn needs_drop(&'tcx self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { + // Avoid querying in simple cases. + match needs_drop_components(self, &tcx.data_layout) { + Err(AlwaysRequiresDrop) => true, + Ok(components) => { + let query_ty = match *components { + [] => return false, + // If we've got a single component, call the query with that + // to increase the chance that we hit the query cache. + [component_ty] => component_ty, + _ => self, + }; + // This doesn't depend on regions, so try to minimize distinct + // query keys used. + let erased = tcx.normalize_erasing_regions(param_env, query_ty); + tcx.needs_drop_raw(param_env.and(erased)) + } + } + } + + /// Returns `true` if equality for this type is both reflexive and structural. + /// + /// Reflexive equality for a type is indicated by an `Eq` impl for that type. + /// + /// Primitive types (`u32`, `str`) have structural equality by definition. For composite data + /// types, equality for the type as a whole is structural when it is the same as equality + /// between all components (fields, array elements, etc.) of that type. For ADTs, structural + /// equality is indicated by an implementation of `PartialStructuralEq` and `StructuralEq` for + /// that type. + /// + /// This function is "shallow" because it may return `true` for a composite type whose fields + /// are not `StructuralEq`. For example, `[T; 4]` has structural equality regardless of `T` + /// because equality for arrays is determined by the equality of each array element. If you + /// want to know whether a given call to `PartialEq::eq` will proceed structurally all the way + /// down, you will need to use a type visitor. + #[inline] + pub fn is_structural_eq_shallow(&'tcx self, tcx: TyCtxt<'tcx>) -> bool { + match self.kind { + // Look for an impl of both `PartialStructuralEq` and `StructuralEq`. + Adt(..) => tcx.has_structural_eq_impls(self), + + // Primitive types that satisfy `Eq`. + Bool | Char | Int(_) | Uint(_) | Str | Never => true, + + // Composite types that satisfy `Eq` when all of their fields do. + // + // Because this function is "shallow", we return `true` for these composites regardless + // of the type(s) contained within. + Ref(..) | Array(..) | Slice(_) | Tuple(..) => true, + + // Raw pointers use bitwise comparison. + RawPtr(_) | FnPtr(_) => true, + + // Floating point numbers are not `Eq`. + Float(_) => false, + + // Conservatively return `false` for all others... + + // Anonymous function types + FnDef(..) | Closure(..) | Dynamic(..) | Generator(..) => false, + + // Generic or inferred types + // + // FIXME(ecstaticmorse): Maybe we should `bug` here? This should probably only be + // called for known, fully-monomorphized types. + Projection(_) | Opaque(..) | Param(_) | Bound(..) | Placeholder(_) | Infer(_) => false, + + Foreign(_) | GeneratorWitness(..) | Error(_) => false, + } + } + + pub fn same_type(a: Ty<'tcx>, b: Ty<'tcx>) -> bool { + match (&a.kind, &b.kind) { + (&Adt(did_a, substs_a), &Adt(did_b, substs_b)) => { + if did_a != did_b { + return false; + } + + substs_a.types().zip(substs_b.types()).all(|(a, b)| Self::same_type(a, b)) + } + _ => a == b, + } + } + + /// Check whether a type is representable. This means it cannot contain unboxed + /// structural recursion. This check is needed for structs and enums. + pub fn is_representable(&'tcx self, tcx: TyCtxt<'tcx>, sp: Span) -> Representability { + // Iterate until something non-representable is found + fn fold_repr<It: Iterator<Item = Representability>>(iter: It) -> Representability { + iter.fold(Representability::Representable, |r1, r2| match (r1, r2) { + (Representability::SelfRecursive(v1), Representability::SelfRecursive(v2)) => { + Representability::SelfRecursive(v1.into_iter().chain(v2).collect()) + } + (r1, r2) => cmp::max(r1, r2), + }) + } + + fn are_inner_types_recursive<'tcx>( + tcx: TyCtxt<'tcx>, + sp: Span, + seen: &mut Vec<Ty<'tcx>>, + representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>, + ty: Ty<'tcx>, + ) -> Representability { + match ty.kind { + Tuple(..) => { + // Find non representable + fold_repr(ty.tuple_fields().map(|ty| { + is_type_structurally_recursive(tcx, sp, seen, representable_cache, ty) + })) + } + // Fixed-length vectors. + // FIXME(#11924) Behavior undecided for zero-length vectors. + Array(ty, _) => { + is_type_structurally_recursive(tcx, sp, seen, representable_cache, ty) + } + Adt(def, substs) => { + // Find non representable fields with their spans + fold_repr(def.all_fields().map(|field| { + let ty = field.ty(tcx, substs); + let span = match field + .did + .as_local() + .map(|id| tcx.hir().local_def_id_to_hir_id(id)) + .and_then(|id| tcx.hir().find(id)) + { + Some(hir::Node::Field(field)) => field.ty.span, + _ => sp, + }; + match is_type_structurally_recursive( + tcx, + span, + seen, + representable_cache, + ty, + ) { + Representability::SelfRecursive(_) => { + Representability::SelfRecursive(vec![span]) + } + x => x, + } + })) + } + Closure(..) => { + // this check is run on type definitions, so we don't expect + // to see closure types + bug!("requires check invoked on inapplicable type: {:?}", ty) + } + _ => Representability::Representable, + } + } + + fn same_struct_or_enum<'tcx>(ty: Ty<'tcx>, def: &'tcx ty::AdtDef) -> bool { + match ty.kind { + Adt(ty_def, _) => ty_def == def, + _ => false, + } + } + + // Does the type `ty` directly (without indirection through a pointer) + // contain any types on stack `seen`? + fn is_type_structurally_recursive<'tcx>( + tcx: TyCtxt<'tcx>, + sp: Span, + seen: &mut Vec<Ty<'tcx>>, + representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>, + ty: Ty<'tcx>, + ) -> Representability { + debug!("is_type_structurally_recursive: {:?} {:?}", ty, sp); + if let Some(representability) = representable_cache.get(ty) { + debug!( + "is_type_structurally_recursive: {:?} {:?} - (cached) {:?}", + ty, sp, representability + ); + return representability.clone(); + } + + let representability = + is_type_structurally_recursive_inner(tcx, sp, seen, representable_cache, ty); + + representable_cache.insert(ty, representability.clone()); + representability + } + + fn is_type_structurally_recursive_inner<'tcx>( + tcx: TyCtxt<'tcx>, + sp: Span, + seen: &mut Vec<Ty<'tcx>>, + representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>, + ty: Ty<'tcx>, + ) -> Representability { + match ty.kind { + Adt(def, _) => { + { + // Iterate through stack of previously seen types. + let mut iter = seen.iter(); + + // The first item in `seen` is the type we are actually curious about. + // We want to return SelfRecursive if this type contains itself. + // It is important that we DON'T take generic parameters into account + // for this check, so that Bar<T> in this example counts as SelfRecursive: + // + // struct Foo; + // struct Bar<T> { x: Bar<Foo> } + + if let Some(&seen_type) = iter.next() { + if same_struct_or_enum(seen_type, def) { + debug!("SelfRecursive: {:?} contains {:?}", seen_type, ty); + return Representability::SelfRecursive(vec![sp]); + } + } + + // We also need to know whether the first item contains other types + // that are structurally recursive. If we don't catch this case, we + // will recurse infinitely for some inputs. + // + // It is important that we DO take generic parameters into account + // here, so that code like this is considered SelfRecursive, not + // ContainsRecursive: + // + // struct Foo { Option<Option<Foo>> } + + for &seen_type in iter { + if ty::TyS::same_type(ty, seen_type) { + debug!("ContainsRecursive: {:?} contains {:?}", seen_type, ty); + return Representability::ContainsRecursive; + } + } + } + + // For structs and enums, track all previously seen types by pushing them + // onto the 'seen' stack. + seen.push(ty); + let out = are_inner_types_recursive(tcx, sp, seen, representable_cache, ty); + seen.pop(); + out + } + _ => { + // No need to push in other cases. + are_inner_types_recursive(tcx, sp, seen, representable_cache, ty) + } + } + } + + debug!("is_type_representable: {:?}", self); + + // To avoid a stack overflow when checking an enum variant or struct that + // contains a different, structurally recursive type, maintain a stack + // of seen types and check recursion for each of them (issues #3008, #3779). + let mut seen: Vec<Ty<'_>> = Vec::new(); + let mut representable_cache = FxHashMap::default(); + let r = is_type_structurally_recursive(tcx, sp, &mut seen, &mut representable_cache, self); + debug!("is_type_representable: {:?} is {:?}", self, r); + r + } + + /// Peel off all reference types in this type until there are none left. + /// + /// This method is idempotent, i.e. `ty.peel_refs().peel_refs() == ty.peel_refs()`. + /// + /// # Examples + /// + /// - `u8` -> `u8` + /// - `&'a mut u8` -> `u8` + /// - `&'a &'b u8` -> `u8` + /// - `&'a *const &'b u8 -> *const &'b u8` + pub fn peel_refs(&'tcx self) -> Ty<'tcx> { + let mut ty = self; + while let Ref(_, inner_ty, _) = ty.kind { + ty = inner_ty; + } + ty + } +} + +pub enum ExplicitSelf<'tcx> { + ByValue, + ByReference(ty::Region<'tcx>, hir::Mutability), + ByRawPointer(hir::Mutability), + ByBox, + Other, +} + +impl<'tcx> ExplicitSelf<'tcx> { + /// Categorizes an explicit self declaration like `self: SomeType` + /// into either `self`, `&self`, `&mut self`, `Box<self>`, or + /// `Other`. + /// This is mainly used to require the arbitrary_self_types feature + /// in the case of `Other`, to improve error messages in the common cases, + /// and to make `Other` non-object-safe. + /// + /// Examples: + /// + /// ``` + /// impl<'a> Foo for &'a T { + /// // Legal declarations: + /// fn method1(self: &&'a T); // ExplicitSelf::ByReference + /// fn method2(self: &'a T); // ExplicitSelf::ByValue + /// fn method3(self: Box<&'a T>); // ExplicitSelf::ByBox + /// fn method4(self: Rc<&'a T>); // ExplicitSelf::Other + /// + /// // Invalid cases will be caught by `check_method_receiver`: + /// fn method_err1(self: &'a mut T); // ExplicitSelf::Other + /// fn method_err2(self: &'static T) // ExplicitSelf::ByValue + /// fn method_err3(self: &&T) // ExplicitSelf::ByReference + /// } + /// ``` + /// + pub fn determine<P>(self_arg_ty: Ty<'tcx>, is_self_ty: P) -> ExplicitSelf<'tcx> + where + P: Fn(Ty<'tcx>) -> bool, + { + use self::ExplicitSelf::*; + + match self_arg_ty.kind { + _ if is_self_ty(self_arg_ty) => ByValue, + ty::Ref(region, ty, mutbl) if is_self_ty(ty) => ByReference(region, mutbl), + ty::RawPtr(ty::TypeAndMut { ty, mutbl }) if is_self_ty(ty) => ByRawPointer(mutbl), + ty::Adt(def, _) if def.is_box() && is_self_ty(self_arg_ty.boxed_ty()) => ByBox, + _ => Other, + } + } +} + +/// Returns a list of types such that the given type needs drop if and only if +/// *any* of the returned types need drop. Returns `Err(AlwaysRequiresDrop)` if +/// this type always needs drop. +pub fn needs_drop_components( + ty: Ty<'tcx>, + target_layout: &TargetDataLayout, +) -> Result<SmallVec<[Ty<'tcx>; 2]>, AlwaysRequiresDrop> { + match ty.kind { + ty::Infer(ty::FreshIntTy(_)) + | ty::Infer(ty::FreshFloatTy(_)) + | ty::Bool + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Never + | ty::FnDef(..) + | ty::FnPtr(_) + | ty::Char + | ty::GeneratorWitness(..) + | ty::RawPtr(_) + | ty::Ref(..) + | ty::Str => Ok(SmallVec::new()), + + // Foreign types can never have destructors. + ty::Foreign(..) => Ok(SmallVec::new()), + + ty::Dynamic(..) | ty::Error(_) => Err(AlwaysRequiresDrop), + + ty::Slice(ty) => needs_drop_components(ty, target_layout), + ty::Array(elem_ty, size) => { + match needs_drop_components(elem_ty, target_layout) { + Ok(v) if v.is_empty() => Ok(v), + res => match size.val.try_to_bits(target_layout.pointer_size) { + // Arrays of size zero don't need drop, even if their element + // type does. + Some(0) => Ok(SmallVec::new()), + Some(_) => res, + // We don't know which of the cases above we are in, so + // return the whole type and let the caller decide what to + // do. + None => Ok(smallvec![ty]), + }, + } + } + // If any field needs drop, then the whole tuple does. + ty::Tuple(..) => ty.tuple_fields().try_fold(SmallVec::new(), move |mut acc, elem| { + acc.extend(needs_drop_components(elem, target_layout)?); + Ok(acc) + }), + + // These require checking for `Copy` bounds or `Adt` destructors. + ty::Adt(..) + | ty::Projection(..) + | ty::Param(_) + | ty::Bound(..) + | ty::Placeholder(..) + | ty::Opaque(..) + | ty::Infer(_) + | ty::Closure(..) + | ty::Generator(..) => Ok(smallvec![ty]), + } +} + +#[derive(Copy, Clone, Debug, HashStable, TyEncodable, TyDecodable)] +pub struct AlwaysRequiresDrop; + +/// Normalizes all opaque types in the given value, replacing them +/// with their underlying types. +pub fn normalize_opaque_types( + tcx: TyCtxt<'tcx>, + val: &'tcx List<ty::Predicate<'tcx>>, +) -> &'tcx List<ty::Predicate<'tcx>> { + let mut visitor = OpaqueTypeExpander { + seen_opaque_tys: FxHashSet::default(), + expanded_cache: FxHashMap::default(), + primary_def_id: None, + found_recursion: false, + check_recursion: false, + tcx, + }; + val.fold_with(&mut visitor) +} + +pub fn provide(providers: &mut ty::query::Providers) { + *providers = ty::query::Providers { normalize_opaque_types, ..*providers } +} diff --git a/compiler/rustc_middle/src/ty/walk.rs b/compiler/rustc_middle/src/ty/walk.rs new file mode 100644 index 00000000000..82c649b8f54 --- /dev/null +++ b/compiler/rustc_middle/src/ty/walk.rs @@ -0,0 +1,182 @@ +//! An iterator over the type substructure. +//! WARNING: this does not keep track of the region depth. + +use crate::ty; +use crate::ty::subst::{GenericArg, GenericArgKind}; +use smallvec::{self, SmallVec}; + +// The TypeWalker's stack is hot enough that it's worth going to some effort to +// avoid heap allocations. +type TypeWalkerStack<'tcx> = SmallVec<[GenericArg<'tcx>; 8]>; + +pub struct TypeWalker<'tcx> { + stack: TypeWalkerStack<'tcx>, + last_subtree: usize, +} + +impl<'tcx> TypeWalker<'tcx> { + pub fn new(root: GenericArg<'tcx>) -> TypeWalker<'tcx> { + TypeWalker { stack: smallvec![root], last_subtree: 1 } + } + + /// Skips the subtree corresponding to the last type + /// returned by `next()`. + /// + /// Example: Imagine you are walking `Foo<Bar<i32>, usize>`. + /// + /// ``` + /// let mut iter: TypeWalker = ...; + /// iter.next(); // yields Foo + /// iter.next(); // yields Bar<i32> + /// iter.skip_current_subtree(); // skips i32 + /// iter.next(); // yields usize + /// ``` + pub fn skip_current_subtree(&mut self) { + self.stack.truncate(self.last_subtree); + } +} + +impl<'tcx> Iterator for TypeWalker<'tcx> { + type Item = GenericArg<'tcx>; + + fn next(&mut self) -> Option<GenericArg<'tcx>> { + debug!("next(): stack={:?}", self.stack); + let next = self.stack.pop()?; + self.last_subtree = self.stack.len(); + push_inner(&mut self.stack, next); + debug!("next: stack={:?}", self.stack); + Some(next) + } +} + +impl GenericArg<'tcx> { + /// Iterator that walks `self` and any types reachable from + /// `self`, in depth-first order. Note that just walks the types + /// that appear in `self`, it does not descend into the fields of + /// structs or variants. For example: + /// + /// ```notrust + /// isize => { isize } + /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize } + /// [isize] => { [isize], isize } + /// ``` + pub fn walk(self) -> TypeWalker<'tcx> { + TypeWalker::new(self) + } + + /// Iterator that walks the immediate children of `self`. Hence + /// `Foo<Bar<i32>, u32>` yields the sequence `[Bar<i32>, u32]` + /// (but not `i32`, like `walk`). + pub fn walk_shallow(self) -> impl Iterator<Item = GenericArg<'tcx>> { + let mut stack = SmallVec::new(); + push_inner(&mut stack, self); + stack.into_iter() + } +} + +impl<'tcx> super::TyS<'tcx> { + /// Iterator that walks `self` and any types reachable from + /// `self`, in depth-first order. Note that just walks the types + /// that appear in `self`, it does not descend into the fields of + /// structs or variants. For example: + /// + /// ```notrust + /// isize => { isize } + /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize } + /// [isize] => { [isize], isize } + /// ``` + pub fn walk(&'tcx self) -> TypeWalker<'tcx> { + TypeWalker::new(self.into()) + } +} + +// We push `GenericArg`s on the stack in reverse order so as to +// maintain a pre-order traversal. As of the time of this +// writing, the fact that the traversal is pre-order is not +// known to be significant to any code, but it seems like the +// natural order one would expect (basically, the order of the +// types as they are written). +fn push_inner<'tcx>(stack: &mut TypeWalkerStack<'tcx>, parent: GenericArg<'tcx>) { + match parent.unpack() { + GenericArgKind::Type(parent_ty) => match parent_ty.kind { + ty::Bool + | ty::Char + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Str + | ty::Infer(_) + | ty::Param(_) + | ty::Never + | ty::Error(_) + | ty::Placeholder(..) + | ty::Bound(..) + | ty::Foreign(..) => {} + + ty::Array(ty, len) => { + stack.push(len.into()); + stack.push(ty.into()); + } + ty::Slice(ty) => { + stack.push(ty.into()); + } + ty::RawPtr(mt) => { + stack.push(mt.ty.into()); + } + ty::Ref(lt, ty, _) => { + stack.push(ty.into()); + stack.push(lt.into()); + } + ty::Projection(data) => { + stack.extend(data.substs.iter().rev()); + } + ty::Dynamic(obj, lt) => { + stack.push(lt.into()); + stack.extend(obj.iter().rev().flat_map(|predicate| { + let (substs, opt_ty) = match predicate.skip_binder() { + ty::ExistentialPredicate::Trait(tr) => (tr.substs, None), + ty::ExistentialPredicate::Projection(p) => (p.substs, Some(p.ty)), + ty::ExistentialPredicate::AutoTrait(_) => + // Empty iterator + { + (ty::InternalSubsts::empty(), None) + } + }; + + substs.iter().rev().chain(opt_ty.map(|ty| ty.into())) + })); + } + ty::Adt(_, substs) + | ty::Opaque(_, substs) + | ty::Closure(_, substs) + | ty::Generator(_, substs, _) + | ty::Tuple(substs) + | ty::FnDef(_, substs) => { + stack.extend(substs.iter().rev()); + } + ty::GeneratorWitness(ts) => { + stack.extend(ts.skip_binder().iter().rev().map(|ty| ty.into())); + } + ty::FnPtr(sig) => { + stack.push(sig.skip_binder().output().into()); + stack.extend(sig.skip_binder().inputs().iter().copied().rev().map(|ty| ty.into())); + } + }, + GenericArgKind::Lifetime(_) => {} + GenericArgKind::Const(parent_ct) => { + stack.push(parent_ct.ty.into()); + match parent_ct.val { + ty::ConstKind::Infer(_) + | ty::ConstKind::Param(_) + | ty::ConstKind::Placeholder(_) + | ty::ConstKind::Bound(..) + | ty::ConstKind::Value(_) + | ty::ConstKind::Error(_) => {} + + ty::ConstKind::Unevaluated(_, substs, _) => { + stack.extend(substs.iter().rev()); + } + } + } + } +} diff --git a/compiler/rustc_middle/src/util/bug.rs b/compiler/rustc_middle/src/util/bug.rs new file mode 100644 index 00000000000..0903ef50898 --- /dev/null +++ b/compiler/rustc_middle/src/util/bug.rs @@ -0,0 +1,52 @@ +// These functions are used by macro expansion for bug! and span_bug! + +use crate::ty::{tls, TyCtxt}; +use rustc_span::{MultiSpan, Span}; +use std::fmt; +use std::panic::Location; + +#[cold] +#[inline(never)] +#[track_caller] +pub fn bug_fmt(args: fmt::Arguments<'_>) -> ! { + // this wrapper mostly exists so I don't have to write a fully + // qualified path of None::<Span> inside the bug!() macro definition + opt_span_bug_fmt(None::<Span>, args, Location::caller()); +} + +#[cold] +#[inline(never)] +#[track_caller] +pub fn span_bug_fmt<S: Into<MultiSpan>>(span: S, args: fmt::Arguments<'_>) -> ! { + opt_span_bug_fmt(Some(span), args, Location::caller()); +} + +fn opt_span_bug_fmt<S: Into<MultiSpan>>( + span: Option<S>, + args: fmt::Arguments<'_>, + location: &Location<'_>, +) -> ! { + tls::with_opt(move |tcx| { + let msg = format!("{}: {}", location, args); + match (tcx, span) { + (Some(tcx), Some(span)) => tcx.sess.diagnostic().span_bug(span, &msg), + (Some(tcx), None) => tcx.sess.diagnostic().bug(&msg), + (None, _) => panic!(msg), + } + }); + unreachable!(); +} + +/// A query to trigger a `delay_span_bug`. Clearly, if one has a `tcx` one can already trigger a +/// `delay_span_bug`, so what is the point of this? It exists to help us test `delay_span_bug`'s +/// interactions with the query system and incremental. +pub fn trigger_delay_span_bug(tcx: TyCtxt<'_>, key: rustc_hir::def_id::DefId) { + tcx.sess.delay_span_bug( + tcx.def_span(key), + "delayed span bug triggered by #[rustc_error(delay_span_bug_from_inside_query)]", + ); +} + +pub fn provide(providers: &mut crate::ty::query::Providers) { + *providers = crate::ty::query::Providers { trigger_delay_span_bug, ..*providers }; +} diff --git a/compiler/rustc_middle/src/util/common.rs b/compiler/rustc_middle/src/util/common.rs new file mode 100644 index 00000000000..1e09702bf27 --- /dev/null +++ b/compiler/rustc_middle/src/util/common.rs @@ -0,0 +1,69 @@ +#![allow(non_camel_case_types)] + +use rustc_data_structures::sync::Lock; + +use std::fmt::Debug; +use std::time::{Duration, Instant}; + +#[cfg(test)] +mod tests; + +pub fn to_readable_str(mut val: usize) -> String { + let mut groups = vec![]; + loop { + let group = val % 1000; + + val /= 1000; + + if val == 0 { + groups.push(group.to_string()); + break; + } else { + groups.push(format!("{:03}", group)); + } + } + + groups.reverse(); + + groups.join("_") +} + +pub fn record_time<T, F>(accu: &Lock<Duration>, f: F) -> T +where + F: FnOnce() -> T, +{ + let start = Instant::now(); + let rv = f(); + let duration = start.elapsed(); + let mut accu = accu.lock(); + *accu = *accu + duration; + rv +} + +pub fn indent<R, F>(op: F) -> R +where + R: Debug, + F: FnOnce() -> R, +{ + // Use in conjunction with the log post-processor like `src/etc/indenter` + // to make debug output more readable. + debug!(">>"); + let r = op(); + debug!("<< (Result = {:?})", r); + r +} + +pub struct Indenter { + _cannot_construct_outside_of_this_module: (), +} + +impl Drop for Indenter { + fn drop(&mut self) { + debug!("<<"); + } +} + +pub fn indenter() -> Indenter { + debug!(">>"); + Indenter { _cannot_construct_outside_of_this_module: () } +} diff --git a/compiler/rustc_middle/src/util/common/tests.rs b/compiler/rustc_middle/src/util/common/tests.rs new file mode 100644 index 00000000000..9a9fb203c62 --- /dev/null +++ b/compiler/rustc_middle/src/util/common/tests.rs @@ -0,0 +1,14 @@ +use super::*; + +#[test] +fn test_to_readable_str() { + assert_eq!("0", to_readable_str(0)); + assert_eq!("1", to_readable_str(1)); + assert_eq!("99", to_readable_str(99)); + assert_eq!("999", to_readable_str(999)); + assert_eq!("1_000", to_readable_str(1_000)); + assert_eq!("1_001", to_readable_str(1_001)); + assert_eq!("999_999", to_readable_str(999_999)); + assert_eq!("1_000_000", to_readable_str(1_000_000)); + assert_eq!("1_234_567", to_readable_str(1_234_567)); +} |