// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. pub use self::Variance::*; pub use self::AssociatedItemContainer::*; pub use self::BorrowKind::*; pub use self::IntVarValue::*; pub use self::LvaluePreference::*; pub use self::fold::TypeFoldable; use dep_graph::{self, DepNode}; use hir::{map as hir_map, FreevarMap, TraitMap}; use middle; use hir::def::{Def, CtorKind, ExportMap}; use hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE}; use middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem}; use middle::region::{CodeExtent, ROOT_CODE_EXTENT}; use mir::Mir; use traits; use ty; use ty::subst::{Subst, Substs}; use ty::walk::TypeWalker; use util::common::MemoizationMap; use util::nodemap::{NodeSet, NodeMap, FxHashMap}; use serialize::{self, Encodable, Encoder}; use std::borrow::Cow; use std::cell::{Cell, RefCell, Ref}; use std::hash::{Hash, Hasher}; use std::iter; use std::ops::Deref; use std::rc::Rc; use std::slice; use std::vec::IntoIter; use std::mem; use syntax::ast::{self, Name, NodeId}; use syntax::attr; use syntax::symbol::{Symbol, InternedString}; use syntax_pos::{DUMMY_SP, Span}; use rustc_const_math::ConstInt; use rustc_data_structures::accumulate_vec::IntoIter as AccIntoIter; use hir; use hir::itemlikevisit::ItemLikeVisitor; pub use self::sty::{Binder, DebruijnIndex}; pub use self::sty::{BareFnTy, FnSig, PolyFnSig}; pub use self::sty::{ClosureTy, InferTy, ParamTy, ProjectionTy, ExistentialPredicate}; pub use self::sty::{ClosureSubsts, TypeAndMut}; pub use self::sty::{TraitRef, TypeVariants, PolyTraitRef}; pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef}; pub use self::sty::{ExistentialProjection, PolyExistentialProjection}; pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region}; pub use self::sty::Issue32330; pub use self::sty::{TyVid, IntVid, FloatVid, RegionVid, SkolemizedRegionVid}; pub use self::sty::BoundRegion::*; pub use self::sty::InferTy::*; pub use self::sty::Region::*; pub use self::sty::TypeVariants::*; pub use self::contents::TypeContents; pub use self::context::{TyCtxt, GlobalArenas, tls}; pub use self::context::{Lift, TypeckTables}; pub use self::trait_def::{TraitDef, TraitFlags}; pub mod adjustment; pub mod cast; pub mod error; pub mod fast_reject; pub mod fold; pub mod inhabitedness; pub mod item_path; pub mod layout; pub mod _match; pub mod maps; pub mod outlives; pub mod relate; pub mod subst; pub mod trait_def; pub mod walk; pub mod wf; pub mod util; mod contents; mod context; mod flags; mod structural_impls; mod sty; pub type Disr = ConstInt; // Data types /// The complete set of all analyses described in this module. This is /// produced by the driver and fed to trans and later passes. #[derive(Clone)] pub struct CrateAnalysis<'tcx> { pub export_map: ExportMap, pub access_levels: middle::privacy::AccessLevels, pub reachable: NodeSet, pub name: String, pub glob_map: Option, pub hir_ty_to_ty: NodeMap>, } #[derive(Clone)] pub struct Resolutions { pub freevars: FreevarMap, pub trait_map: TraitMap, pub maybe_unused_trait_imports: NodeSet, } #[derive(Clone, Copy, PartialEq, Eq, Debug)] pub enum AssociatedItemContainer { TraitContainer(DefId), ImplContainer(DefId), } impl AssociatedItemContainer { 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, PartialEq, Eq, Hash, Debug)] pub struct ImplHeader<'tcx> { pub impl_def_id: DefId, pub self_ty: Ty<'tcx>, pub trait_ref: Option>, pub predicates: Vec>, } impl<'a, 'gcx, 'tcx> ImplHeader<'tcx> { pub fn with_fresh_ty_vars(selcx: &mut traits::SelectionContext<'a, 'gcx, 'tcx>, impl_def_id: DefId) -> ImplHeader<'tcx> { let tcx = selcx.tcx(); let impl_substs = selcx.infcx().fresh_substs_for_item(DUMMY_SP, impl_def_id); let header = ImplHeader { impl_def_id: impl_def_id, self_ty: tcx.item_type(impl_def_id), trait_ref: tcx.impl_trait_ref(impl_def_id), predicates: tcx.item_predicates(impl_def_id).predicates }.subst(tcx, impl_substs); let traits::Normalized { value: mut header, obligations } = traits::normalize(selcx, traits::ObligationCause::dummy(), &header); header.predicates.extend(obligations.into_iter().map(|o| o.predicate)); header } } #[derive(Copy, Clone, Debug)] pub struct AssociatedItem { pub def_id: DefId, pub name: Name, pub kind: AssociatedKind, pub vis: Visibility, pub defaultness: hir::Defaultness, pub container: AssociatedItemContainer, /// Whether this is a method with an explicit self /// as its first argument, allowing method calls. pub method_has_self_argument: bool, } #[derive(Copy, Clone, PartialEq, Eq, Debug, RustcEncodable, RustcDecodable)] pub enum AssociatedKind { Const, Method, Type } impl AssociatedItem { pub fn def(&self) -> Def { match self.kind { AssociatedKind::Const => Def::AssociatedConst(self.def_id), AssociatedKind::Method => Def::Method(self.def_id), AssociatedKind::Type => Def::AssociatedTy(self.def_id), } } } #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable)] 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; 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<'a, 'gcx, 'tcx> DefIdTree for TyCtxt<'a, 'gcx, 'tcx> { fn parent(self, id: DefId) -> Option { self.def_key(id).parent.map(|index| DefId { index: index, ..id }) } } impl Visibility { pub fn from_hir(visibility: &hir::Visibility, id: NodeId, tcx: TyCtxt) -> Self { match *visibility { hir::Public => Visibility::Public, hir::Visibility::Crate => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)), hir::Visibility::Restricted { ref path, .. } => match path.def { // 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. Def::Err => Visibility::Public, def => Visibility::Restricted(def.def_id()), }, hir::Inherited => { Visibility::Restricted(tcx.hir.local_def_id(tcx.hir.get_module_parent(id))) } } } /// Returns true if an item with this visibility is accessible from the given block. pub fn is_accessible_from(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(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) } } #[derive(Clone, PartialEq, RustcDecodable, RustcEncodable, Copy)] pub enum Variance { Covariant, // T <: T iff A <: B -- e.g., function return type Invariant, // T <: T iff B == A -- e.g., type of mutable cell Contravariant, // T <: T iff B <: A -- e.g., function param type Bivariant, // T <: T -- e.g., unused type parameter } #[derive(Clone, Copy, Debug, RustcDecodable, RustcEncodable)] pub struct MethodCallee<'tcx> { /// Impl method ID, for inherent methods, or trait method ID, otherwise. pub def_id: DefId, pub ty: Ty<'tcx>, pub substs: &'tcx Substs<'tcx> } /// With method calls, we store some extra information in /// side tables (i.e method_map). We use /// MethodCall as a key to index into these tables instead of /// just directly using the expression's NodeId. The reason /// for this being that we may apply adjustments (coercions) /// with the resulting expression also needing to use the /// side tables. The problem with this is that we don't /// assign a separate NodeId to this new expression /// and so it would clash with the base expression if both /// needed to add to the side tables. Thus to disambiguate /// we also keep track of whether there's an adjustment in /// our key. #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] pub struct MethodCall { pub expr_id: NodeId, pub autoderef: u32 } impl MethodCall { pub fn expr(id: NodeId) -> MethodCall { MethodCall { expr_id: id, autoderef: 0 } } pub fn autoderef(expr_id: NodeId, autoderef: u32) -> MethodCall { MethodCall { expr_id: expr_id, autoderef: 1 + autoderef } } } // maps from an expression id that corresponds to a method call to the details // of the method to be invoked pub type MethodMap<'tcx> = FxHashMap>; // 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, } /// Describes the fragment-state associated with a NodeId. /// /// Currently only unfragmented paths have entries in the table, /// but longer-term this enum is expected to expand to also /// include data for fragmented paths. #[derive(Copy, Clone, Debug)] pub enum FragmentInfo { Moved { var: NodeId, move_expr: NodeId }, Assigned { var: NodeId, assign_expr: NodeId, assignee_id: NodeId }, } // 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. bitflags! { flags TypeFlags: u32 { const HAS_PARAMS = 1 << 0, const HAS_SELF = 1 << 1, const HAS_TY_INFER = 1 << 2, const HAS_RE_INFER = 1 << 3, const HAS_RE_SKOL = 1 << 4, const HAS_RE_EARLY_BOUND = 1 << 5, const HAS_FREE_REGIONS = 1 << 6, const HAS_TY_ERR = 1 << 7, const HAS_PROJECTION = 1 << 8, const HAS_TY_CLOSURE = 1 << 9, // true if there are "names" of types and regions and so forth // that are local to a particular fn const HAS_LOCAL_NAMES = 1 << 10, // Present if the type belongs in a local type context. // Only set for TyInfer other than Fresh. const KEEP_IN_LOCAL_TCX = 1 << 11, // Is there a projection that does not involve a bound region? // Currently we can't normalize projections w/ bound regions. const HAS_NORMALIZABLE_PROJECTION = 1 << 12, const NEEDS_SUBST = TypeFlags::HAS_PARAMS.bits | TypeFlags::HAS_SELF.bits | TypeFlags::HAS_RE_EARLY_BOUND.bits, // Flags representing the nominal content of a type, // computed by FlagsComputation. If you add a new nominal // flag, it should be added here too. const NOMINAL_FLAGS = TypeFlags::HAS_PARAMS.bits | TypeFlags::HAS_SELF.bits | TypeFlags::HAS_TY_INFER.bits | TypeFlags::HAS_RE_INFER.bits | TypeFlags::HAS_RE_SKOL.bits | TypeFlags::HAS_RE_EARLY_BOUND.bits | TypeFlags::HAS_FREE_REGIONS.bits | TypeFlags::HAS_TY_ERR.bits | TypeFlags::HAS_PROJECTION.bits | TypeFlags::HAS_TY_CLOSURE.bits | TypeFlags::HAS_LOCAL_NAMES.bits | TypeFlags::KEEP_IN_LOCAL_TCX.bits, // Caches for type_is_sized, type_moves_by_default const SIZEDNESS_CACHED = 1 << 16, const IS_SIZED = 1 << 17, const MOVENESS_CACHED = 1 << 18, const MOVES_BY_DEFAULT = 1 << 19, } } pub struct TyS<'tcx> { pub sty: TypeVariants<'tcx>, pub flags: Cell, // the maximal depth of any bound regions appearing in this type. region_depth: u32, } impl<'tcx> PartialEq for TyS<'tcx> { #[inline] fn eq(&self, other: &TyS<'tcx>) -> bool { // (self as *const _) == (other as *const _) (self as *const TyS<'tcx>) == (other as *const TyS<'tcx>) } } impl<'tcx> Eq for TyS<'tcx> {} impl<'tcx> Hash for TyS<'tcx> { fn hash(&self, s: &mut H) { (self as *const TyS).hash(s) } } pub type Ty<'tcx> = &'tcx TyS<'tcx>; impl<'tcx> serialize::UseSpecializedEncodable for Ty<'tcx> {} impl<'tcx> serialize::UseSpecializedDecodable for Ty<'tcx> {} /// 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 + length for both /// equality comparisons and hashing. #[derive(Debug, RustcEncodable)] pub struct Slice([T]); impl PartialEq for Slice { #[inline] fn eq(&self, other: &Slice) -> bool { (&self.0 as *const [T]) == (&other.0 as *const [T]) } } impl Eq for Slice {} impl Hash for Slice { fn hash(&self, s: &mut H) { (self.as_ptr(), self.len()).hash(s) } } impl Deref for Slice { type Target = [T]; fn deref(&self) -> &[T] { &self.0 } } impl<'a, T> IntoIterator for &'a Slice { type Item = &'a T; type IntoIter = <&'a [T] as IntoIterator>::IntoIter; fn into_iter(self) -> Self::IntoIter { self[..].iter() } } impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Slice> {} impl Slice { pub fn empty<'a>() -> &'a Slice { unsafe { mem::transmute(slice::from_raw_parts(0x1 as *const T, 0)) } } } /// Upvars do not get their own node-id. 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, RustcEncodable, RustcDecodable)] pub struct UpvarId { pub var_id: NodeId, pub closure_expr_id: NodeId, } #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, Copy)] 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, RustcEncodable, RustcDecodable)] 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. ByValue, /// Upvar is captured by reference. ByRef(UpvarBorrow<'tcx>), } #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable)] 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: &'tcx ty::Region, } pub type UpvarCaptureMap<'tcx> = FxHashMap>; #[derive(Copy, Clone)] pub struct ClosureUpvar<'tcx> { pub def: Def, pub span: Span, pub ty: Ty<'tcx>, } #[derive(Clone, Copy, PartialEq)] pub enum IntVarValue { IntType(ast::IntTy), UintType(ast::UintTy), } #[derive(Clone, RustcEncodable, RustcDecodable)] pub struct TypeParameterDef<'tcx> { pub name: Name, pub def_id: DefId, pub index: u32, pub default_def_id: DefId, // for use in error reporing about defaults pub default: Option>, /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute /// on generic parameter `T`, asserts data behind the parameter /// `T` won't be accessed during the parent type's `Drop` impl. pub pure_wrt_drop: bool, } #[derive(Copy, Clone, RustcEncodable, RustcDecodable)] pub struct RegionParameterDef { pub name: Name, pub def_id: DefId, pub index: u32, /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute /// on generic parameter `'a`, asserts data of lifetime `'a` /// won't be accessed during the parent type's `Drop` impl. pub pure_wrt_drop: bool, } impl RegionParameterDef { pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion { ty::EarlyBoundRegion { index: self.index, name: self.name, } } pub fn to_bound_region(&self) -> ty::BoundRegion { // this is an early bound region, so unaffected by #32330 ty::BoundRegion::BrNamed(self.def_id, self.name, Issue32330::WontChange) } } /// Information about the formal type/lifetime parameters associated /// with an item or method. Analogous to hir::Generics. #[derive(Clone, Debug, RustcEncodable, RustcDecodable)] pub struct Generics<'tcx> { pub parent: Option, pub parent_regions: u32, pub parent_types: u32, pub regions: Vec, pub types: Vec>, pub has_self: bool, } impl<'tcx> Generics<'tcx> { pub fn parent_count(&self) -> usize { self.parent_regions as usize + self.parent_types as usize } pub fn own_count(&self) -> usize { self.regions.len() + self.types.len() } pub fn count(&self) -> usize { self.parent_count() + self.own_count() } pub fn region_param(&self, param: &EarlyBoundRegion) -> &RegionParameterDef { &self.regions[param.index as usize - self.has_self as usize] } pub fn type_param(&self, param: &ParamTy) -> &TypeParameterDef<'tcx> { &self.types[param.idx as usize - self.has_self as usize - self.regions.len()] } } /// Bounds on generics. #[derive(Clone)] pub struct GenericPredicates<'tcx> { pub parent: Option, pub predicates: Vec>, } impl<'tcx> serialize::UseSpecializedEncodable for GenericPredicates<'tcx> {} impl<'tcx> serialize::UseSpecializedDecodable for GenericPredicates<'tcx> {} impl<'a, 'gcx, 'tcx> GenericPredicates<'tcx> { pub fn instantiate(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>) -> InstantiatedPredicates<'tcx> { let mut instantiated = InstantiatedPredicates::empty(); self.instantiate_into(tcx, &mut instantiated, substs); instantiated } pub fn instantiate_own(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>) -> InstantiatedPredicates<'tcx> { InstantiatedPredicates { predicates: self.predicates.subst(tcx, substs) } } fn instantiate_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, instantiated: &mut InstantiatedPredicates<'tcx>, substs: &Substs<'tcx>) { if let Some(def_id) = self.parent { tcx.item_predicates(def_id).instantiate_into(tcx, instantiated, substs); } instantiated.predicates.extend(self.predicates.iter().map(|p| p.subst(tcx, substs))) } pub fn instantiate_supertrait(&self, tcx: TyCtxt<'a, 'gcx, '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() } } } #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] pub enum Predicate<'tcx> { /// Corresponds to `where Foo : Bar`. `Foo` here would be /// the `Self` type of the trait reference and `A`, `B`, and `C` /// would be the type parameters. Trait(PolyTraitPredicate<'tcx>), /// where `T1 == T2`. Equate(PolyEquatePredicate<'tcx>), /// where 'a : 'b RegionOutlives(PolyRegionOutlivesPredicate<'tcx>), /// where T : 'a TypeOutlives(PolyTypeOutlivesPredicate<'tcx>), /// where ::Name == X, approximately. /// See `ProjectionPredicate` struct for details. Projection(PolyProjectionPredicate<'tcx>), /// no syntax: T WF WellFormed(Ty<'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, ClosureKind), } impl<'a, 'gcx, '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<'a, 'gcx, 'tcx>, trait_ref: &ty::PolyTraitRef<'tcx>) -> ty::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.0.substs; match *self { Predicate::Trait(ty::Binder(ref data)) => Predicate::Trait(ty::Binder(data.subst(tcx, substs))), Predicate::Equate(ty::Binder(ref data)) => Predicate::Equate(ty::Binder(data.subst(tcx, substs))), Predicate::RegionOutlives(ty::Binder(ref data)) => Predicate::RegionOutlives(ty::Binder(data.subst(tcx, substs))), Predicate::TypeOutlives(ty::Binder(ref data)) => Predicate::TypeOutlives(ty::Binder(data.subst(tcx, substs))), Predicate::Projection(ty::Binder(ref data)) => Predicate::Projection(ty::Binder(data.subst(tcx, substs))), Predicate::WellFormed(data) => Predicate::WellFormed(data.subst(tcx, substs)), Predicate::ObjectSafe(trait_def_id) => Predicate::ObjectSafe(trait_def_id), Predicate::ClosureKind(closure_def_id, kind) => Predicate::ClosureKind(closure_def_id, kind), } } } #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] pub struct TraitPredicate<'tcx> { pub trait_ref: TraitRef<'tcx> } pub type PolyTraitPredicate<'tcx> = ty::Binder>; impl<'tcx> TraitPredicate<'tcx> { pub fn def_id(&self) -> DefId { self.trait_ref.def_id } /// Creates the dep-node for selecting/evaluating this trait reference. fn dep_node(&self) -> DepNode { // Ideally, the dep-node would just have all the input types // in it. But they are limited to including def-ids. So as an // approximation we include the def-ids for all nominal types // found somewhere. This means that we will e.g. conflate the // dep-nodes for `u32: SomeTrait` and `u64: SomeTrait`, but we // would have distinct dep-nodes for `Vec: SomeTrait`, // `Rc: SomeTrait`, and `(Vec, Rc): SomeTrait`. // Note that it's always sound to conflate dep-nodes, it just // leads to more recompilation. let def_ids: Vec<_> = self.input_types() .flat_map(|t| t.walk()) .filter_map(|t| match t.sty { ty::TyAdt(adt_def, _) => Some(adt_def.did), _ => None }) .chain(iter::once(self.def_id())) .collect(); DepNode::TraitSelect(def_ids) } pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator> + 'a { self.trait_ref.input_types() } 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 def-id does not care about regions self.0.def_id() } pub fn dep_node(&self) -> DepNode { // ok to skip binder since depnode does not care about regions self.0.dep_node() } } #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] pub struct EquatePredicate<'tcx>(pub Ty<'tcx>, pub Ty<'tcx>); // `0 == 1` pub type PolyEquatePredicate<'tcx> = ty::Binder>; #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] pub struct OutlivesPredicate(pub A, pub B); // `A : B` pub type PolyOutlivesPredicate = ty::Binder>; pub type PolyRegionOutlivesPredicate<'tcx> = PolyOutlivesPredicate<&'tcx ty::Region, &'tcx ty::Region>; pub type PolyTypeOutlivesPredicate<'tcx> = PolyOutlivesPredicate, &'tcx ty::Region>; /// 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. `>::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, RustcEncodable, RustcDecodable)] pub struct ProjectionPredicate<'tcx> { pub projection_ty: ProjectionTy<'tcx>, pub ty: Ty<'tcx>, } pub type PolyProjectionPredicate<'tcx> = Binder>; impl<'tcx> PolyProjectionPredicate<'tcx> { pub fn item_name(&self) -> Name { self.0.projection_ty.item_name // safe to skip the binder to access a name } } 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> { assert!(!self.has_escaping_regions()); ty::Binder(self.clone()) } } 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) } } impl<'tcx> ToPolyTraitRef<'tcx> for PolyProjectionPredicate<'tcx> { fn to_poly_trait_ref(&self) -> 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. ty::Binder(self.0.projection_ty.trait_ref) } } pub trait ToPredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx>; } impl<'tcx> ToPredicate<'tcx> for TraitRef<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { // we're about to add a binder, so let's check that we don't // accidentally capture anything, or else that might be some // weird debruijn accounting. assert!(!self.has_escaping_regions()); ty::Predicate::Trait(ty::Binder(ty::TraitPredicate { trait_ref: self.clone() })) } } impl<'tcx> ToPredicate<'tcx> for PolyTraitRef<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { ty::Predicate::Trait(self.to_poly_trait_predicate()) } } impl<'tcx> ToPredicate<'tcx> for PolyEquatePredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { Predicate::Equate(self.clone()) } } impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { Predicate::RegionOutlives(self.clone()) } } impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { Predicate::TypeOutlives(self.clone()) } } impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { Predicate::Projection(self.clone()) } } impl<'tcx> Predicate<'tcx> { /// Iterates over the types in this predicate. Note that in all /// cases this is skipping over a binder, so late-bound regions /// with depth 0 are bound by the predicate. pub fn walk_tys(&self) -> IntoIter> { let vec: Vec<_> = match *self { ty::Predicate::Trait(ref data) => { data.skip_binder().input_types().collect() } ty::Predicate::Equate(ty::Binder(ref data)) => { vec![data.0, data.1] } ty::Predicate::TypeOutlives(ty::Binder(ref data)) => { vec![data.0] } ty::Predicate::RegionOutlives(..) => { vec![] } ty::Predicate::Projection(ref data) => { let trait_inputs = data.0.projection_ty.trait_ref.input_types(); trait_inputs.chain(Some(data.0.ty)).collect() } ty::Predicate::WellFormed(data) => { vec![data] } ty::Predicate::ObjectSafe(_trait_def_id) => { vec![] } ty::Predicate::ClosureKind(_closure_def_id, _kind) => { vec![] } }; // The only reason to collect into a vector here is that I was // too lazy to make the full (somewhat complicated) iterator // type that would be needed here. But I wanted this fn to // return an iterator conceptually, rather than a `Vec`, so as // to be closer to `Ty::walk`. vec.into_iter() } pub fn to_opt_poly_trait_ref(&self) -> Option> { match *self { Predicate::Trait(ref t) => { Some(t.to_poly_trait_ref()) } Predicate::Projection(..) | Predicate::Equate(..) | Predicate::RegionOutlives(..) | Predicate::WellFormed(..) | Predicate::ObjectSafe(..) | Predicate::ClosureKind(..) | Predicate::TypeOutlives(..) => { 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> { ... } /// /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like /// `[[], [U:Bar]]`. Now if there were some particular reference /// like `Foo`, then the `InstantiatedPredicates` would be `[[], /// [usize:Bar]]`. #[derive(Clone)] pub struct InstantiatedPredicates<'tcx> { pub predicates: Vec>, } impl<'tcx> InstantiatedPredicates<'tcx> { pub fn empty() -> InstantiatedPredicates<'tcx> { InstantiatedPredicates { predicates: vec![] } } pub fn is_empty(&self) -> bool { self.predicates.is_empty() } } impl<'tcx> TraitRef<'tcx> { pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> { TraitRef { def_id: def_id, substs: substs } } pub fn self_ty(&self) -> Ty<'tcx> { self.substs.type_at(0) } pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator> + 'a { // Select only the "input types" from a trait-reference. For // now this is all the types that appear in the // trait-reference, but it should eventually exclude // associated types. self.substs.types() } } /// When type checking, we use the `ParameterEnvironment` to track /// details about the type/lifetime parameters that are in scope. /// It primarily stores the bounds information. /// /// Note: This information might seem to be redundant with the data in /// `tcx.ty_param_defs`, but it is not. That table contains the /// parameter definitions from an "outside" perspective, but this /// struct will contain the bounds for a parameter as seen from inside /// the function body. Currently the only real distinction is that /// bound lifetime parameters are replaced with free ones, but in the /// future I hope to refine the representation of types so as to make /// more distinctions clearer. #[derive(Clone)] pub struct ParameterEnvironment<'tcx> { /// See `construct_free_substs` for details. pub free_substs: &'tcx Substs<'tcx>, /// Each type parameter has an implicit region bound that /// indicates it must outlive at least the function body (the user /// may specify stronger requirements). This field indicates the /// region of the callee. pub implicit_region_bound: &'tcx ty::Region, /// Obligations that the caller must satisfy. This is basically /// the set of bounds on the in-scope type parameters, translated /// into Obligations, and elaborated and normalized. pub caller_bounds: Vec>, /// Scope that is attached to free regions for this scope. This /// is usually the id of the fn body, but for more abstract scopes /// like structs we often use the node-id of the struct. /// /// FIXME(#3696). It would be nice to refactor so that free /// regions don't have this implicit scope and instead introduce /// relationships in the environment. pub free_id_outlive: CodeExtent, /// A cache for `moves_by_default`. pub is_copy_cache: RefCell, bool>>, /// A cache for `type_is_sized` pub is_sized_cache: RefCell, bool>>, } impl<'a, 'tcx> ParameterEnvironment<'tcx> { pub fn with_caller_bounds(&self, caller_bounds: Vec>) -> ParameterEnvironment<'tcx> { ParameterEnvironment { free_substs: self.free_substs, implicit_region_bound: self.implicit_region_bound, caller_bounds: caller_bounds, free_id_outlive: self.free_id_outlive, is_copy_cache: RefCell::new(FxHashMap()), is_sized_cache: RefCell::new(FxHashMap()), } } /// Construct a parameter environment given an item, impl item, or trait item pub fn for_item(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: NodeId) -> ParameterEnvironment<'tcx> { match tcx.hir.find(id) { Some(hir_map::NodeImplItem(ref impl_item)) => { match impl_item.node { hir::ImplItemKind::Type(_) | hir::ImplItemKind::Const(..) => { // associated types don't have their own entry (for some reason), // so for now just grab environment for the impl let impl_id = tcx.hir.get_parent(id); let impl_def_id = tcx.hir.local_def_id(impl_id); tcx.construct_parameter_environment(impl_item.span, impl_def_id, tcx.region_maps.item_extent(id)) } hir::ImplItemKind::Method(_, ref body) => { tcx.construct_parameter_environment( impl_item.span, tcx.hir.local_def_id(id), tcx.region_maps.call_site_extent(id, body.node_id)) } } } Some(hir_map::NodeTraitItem(trait_item)) => { match trait_item.node { hir::TraitItemKind::Type(..) | hir::TraitItemKind::Const(..) => { // associated types don't have their own entry (for some reason), // so for now just grab environment for the trait let trait_id = tcx.hir.get_parent(id); let trait_def_id = tcx.hir.local_def_id(trait_id); tcx.construct_parameter_environment(trait_item.span, trait_def_id, tcx.region_maps.item_extent(id)) } hir::TraitItemKind::Method(_, ref body) => { // Use call-site for extent (unless this is a // trait method with no default; then fallback // to the method id). let extent = if let hir::TraitMethod::Provided(body_id) = *body { // default impl: use call_site extent as free_id_outlive bound. tcx.region_maps.call_site_extent(id, body_id.node_id) } else { // no default impl: use item extent as free_id_outlive bound. tcx.region_maps.item_extent(id) }; tcx.construct_parameter_environment( trait_item.span, tcx.hir.local_def_id(id), extent) } } } Some(hir_map::NodeItem(item)) => { match item.node { hir::ItemFn(.., body_id) => { // We assume this is a function. let fn_def_id = tcx.hir.local_def_id(id); tcx.construct_parameter_environment( item.span, fn_def_id, tcx.region_maps.call_site_extent(id, body_id.node_id)) } hir::ItemEnum(..) | hir::ItemStruct(..) | hir::ItemUnion(..) | hir::ItemTy(..) | hir::ItemImpl(..) | hir::ItemConst(..) | hir::ItemStatic(..) => { let def_id = tcx.hir.local_def_id(id); tcx.construct_parameter_environment(item.span, def_id, tcx.region_maps.item_extent(id)) } hir::ItemTrait(..) => { let def_id = tcx.hir.local_def_id(id); tcx.construct_parameter_environment(item.span, def_id, tcx.region_maps.item_extent(id)) } _ => { span_bug!(item.span, "ParameterEnvironment::for_item(): can't create a parameter \ environment for this kind of item") } } } Some(hir_map::NodeExpr(expr)) => { // This is a convenience to allow closures to work. if let hir::ExprClosure(.., body, _) = expr.node { let def_id = tcx.hir.local_def_id(id); let base_def_id = tcx.closure_base_def_id(def_id); tcx.construct_parameter_environment( expr.span, base_def_id, tcx.region_maps.call_site_extent(id, body.node_id)) } else { tcx.empty_parameter_environment() } } Some(hir_map::NodeForeignItem(item)) => { let def_id = tcx.hir.local_def_id(id); tcx.construct_parameter_environment(item.span, def_id, ROOT_CODE_EXTENT) } _ => { bug!("ParameterEnvironment::from_item(): \ `{}` is not an item", tcx.hir.node_to_string(id)) } } } } bitflags! { flags AdtFlags: u32 { const NO_ADT_FLAGS = 0, const IS_ENUM = 1 << 0, const IS_DTORCK = 1 << 1, // is this a dtorck type? const IS_DTORCK_VALID = 1 << 2, const IS_PHANTOM_DATA = 1 << 3, const IS_SIMD = 1 << 4, const IS_FUNDAMENTAL = 1 << 5, const IS_UNION = 1 << 6, const IS_BOX = 1 << 7, } } #[derive(Debug)] pub struct VariantDef { /// The variant's DefId. If this is a tuple-like struct, /// this is the DefId of the struct's ctor. pub did: DefId, pub name: Name, // struct's name if this is a struct pub disr_val: Disr, pub fields: Vec, pub ctor_kind: CtorKind, } #[derive(Debug)] pub struct FieldDef { pub did: DefId, pub name: Name, pub vis: Visibility, } /// The definition of an abstract data type - a struct or enum. /// /// These are all interned (by intern_adt_def) into the adt_defs /// table. pub struct AdtDef { pub did: DefId, pub variants: Vec, destructor: Cell>, flags: Cell } impl PartialEq for AdtDef { // AdtDef are always interned and this is part of TyS equality #[inline] fn eq(&self, other: &Self) -> bool { self as *const _ == other as *const _ } } impl Eq for AdtDef {} impl Hash for AdtDef { #[inline] fn hash(&self, s: &mut H) { (self as *const AdtDef).hash(s) } } impl<'tcx> serialize::UseSpecializedEncodable for &'tcx AdtDef { fn default_encode(&self, s: &mut S) -> Result<(), S::Error> { self.did.encode(s) } } impl<'tcx> serialize::UseSpecializedDecodable for &'tcx AdtDef {} #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub enum AdtKind { Struct, Union, Enum } impl<'a, 'gcx, 'tcx> AdtDef { fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>, did: DefId, kind: AdtKind, variants: Vec) -> Self { let mut flags = AdtFlags::NO_ADT_FLAGS; let attrs = tcx.get_attrs(did); if attr::contains_name(&attrs, "fundamental") { flags = flags | AdtFlags::IS_FUNDAMENTAL; } if tcx.lookup_simd(did) { flags = flags | AdtFlags::IS_SIMD; } if Some(did) == tcx.lang_items.phantom_data() { flags = flags | AdtFlags::IS_PHANTOM_DATA; } if Some(did) == tcx.lang_items.owned_box() { flags = flags | AdtFlags::IS_BOX; } match kind { AdtKind::Enum => flags = flags | AdtFlags::IS_ENUM, AdtKind::Union => flags = flags | AdtFlags::IS_UNION, AdtKind::Struct => {} } AdtDef { did: did, variants: variants, flags: Cell::new(flags), destructor: Cell::new(None), } } fn calculate_dtorck(&'gcx self, tcx: TyCtxt) { if tcx.is_adt_dtorck(self) { self.flags.set(self.flags.get() | AdtFlags::IS_DTORCK); } self.flags.set(self.flags.get() | AdtFlags::IS_DTORCK_VALID) } #[inline] pub fn is_struct(&self) -> bool { !self.is_union() && !self.is_enum() } #[inline] pub fn is_union(&self) -> bool { self.flags.get().intersects(AdtFlags::IS_UNION) } #[inline] pub fn is_enum(&self) -> bool { self.flags.get().intersects(AdtFlags::IS_ENUM) } /// Returns the kind of the ADT - Struct or Enum. #[inline] pub fn adt_kind(&self) -> AdtKind { if self.is_enum() { AdtKind::Enum } else if self.is_union() { AdtKind::Union } else { AdtKind::Struct } } pub fn descr(&self) -> &'static str { match self.adt_kind() { AdtKind::Struct => "struct", AdtKind::Union => "union", AdtKind::Enum => "enum", } } pub fn variant_descr(&self) -> &'static str { match self.adt_kind() { AdtKind::Struct => "struct", AdtKind::Union => "union", AdtKind::Enum => "variant", } } /// Returns whether this is a dtorck type. If this returns /// true, this type being safe for destruction requires it to be /// alive; Otherwise, only the contents are required to be. #[inline] pub fn is_dtorck(&'gcx self, tcx: TyCtxt) -> bool { if !self.flags.get().intersects(AdtFlags::IS_DTORCK_VALID) { self.calculate_dtorck(tcx) } self.flags.get().intersects(AdtFlags::IS_DTORCK) } /// Returns whether this type is #[fundamental] for the purposes /// of coherence checking. #[inline] pub fn is_fundamental(&self) -> bool { self.flags.get().intersects(AdtFlags::IS_FUNDAMENTAL) } #[inline] pub fn is_simd(&self) -> bool { self.flags.get().intersects(AdtFlags::IS_SIMD) } /// Returns true if this is PhantomData. #[inline] pub fn is_phantom_data(&self) -> bool { self.flags.get().intersects(AdtFlags::IS_PHANTOM_DATA) } /// Returns true if this is Box. #[inline] pub fn is_box(&self) -> bool { self.flags.get().intersects(AdtFlags::IS_BOX) } /// Returns whether this type has a destructor. pub fn has_dtor(&self) -> bool { self.destructor.get().is_some() } /// Asserts this is a struct and returns the struct's unique /// variant. pub fn struct_variant(&self) -> &VariantDef { assert!(!self.is_enum()); &self.variants[0] } #[inline] pub fn predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> GenericPredicates<'gcx> { tcx.item_predicates(self.did) } /// Returns an iterator over all fields contained /// by this ADT. #[inline] pub fn all_fields<'s>(&'s self) -> impl Iterator { self.variants.iter().flat_map(|v| v.fields.iter()) } #[inline] pub fn is_univariant(&self) -> bool { self.variants.len() == 1 } pub fn is_payloadfree(&self) -> bool { !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty()) } pub fn variant_with_id(&self, vid: DefId) -> &VariantDef { self.variants .iter() .find(|v| v.did == vid) .expect("variant_with_id: unknown variant") } pub fn variant_index_with_id(&self, vid: DefId) -> usize { self.variants .iter() .position(|v| v.did == vid) .expect("variant_index_with_id: unknown variant") } pub fn variant_of_def(&self, def: Def) -> &VariantDef { match def { Def::Variant(vid) | Def::VariantCtor(vid, ..) => self.variant_with_id(vid), Def::Struct(..) | Def::StructCtor(..) | Def::Union(..) | Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => self.struct_variant(), _ => bug!("unexpected def {:?} in variant_of_def", def) } } pub fn destructor(&self) -> Option { self.destructor.get() } pub fn set_destructor(&self, dtor: DefId) { self.destructor.set(Some(dtor)); } /// Returns a simpler type such that `Self: Sized` if and only /// if that type is Sized, or `TyErr` if this type is recursive. /// /// HACK: instead of returning a list of types, this function can /// return a tuple. In that case, the result is Sized only if /// all elements of the tuple are Sized. /// /// This is generally the `struct_tail` if this is a struct, or a /// tuple of them if this is an enum. /// /// 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<'a, 'gcx, 'tcx>) -> Ty<'tcx> { self.calculate_sized_constraint_inner(tcx.global_tcx(), &mut Vec::new()) } /// Calculates the Sized-constraint. /// /// As the Sized-constraint of enums can be a *set* of types, /// the Sized-constraint may need to be a set also. Because introducing /// a new type of IVar is currently a complex affair, the Sized-constraint /// may be a tuple. /// /// In fact, there are only a few options for the constraint: /// - `bool`, if the type is always Sized /// - an obviously-unsized type /// - a type parameter or projection whose Sizedness can't be known /// - a tuple of type parameters or projections, if there are multiple /// such. /// - a TyError, if a type contained itself. The representability /// check should catch this case. fn calculate_sized_constraint_inner(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, stack: &mut Vec) -> Ty<'tcx> { if let Some(ty) = tcx.adt_sized_constraint.borrow().get(&self.did) { return ty; } // Follow the memoization pattern: push the computation of // DepNode::SizedConstraint as our current task. let _task = tcx.dep_graph.in_task(DepNode::SizedConstraint(self.did)); if stack.contains(&self.did) { debug!("calculate_sized_constraint: {:?} is recursive", self); // This should be reported as an error by `check_representable`. // // Consider the type as Sized in the meanwhile to avoid // further errors. tcx.adt_sized_constraint.borrow_mut().insert(self.did, tcx.types.err); return tcx.types.err; } stack.push(self.did); let tys : Vec<_> = self.variants.iter().flat_map(|v| { v.fields.last() }).flat_map(|f| { let ty = tcx.item_type(f.did); self.sized_constraint_for_ty(tcx, stack, ty) }).collect(); let self_ = stack.pop().unwrap(); assert_eq!(self_, self.did); let ty = match tys.len() { _ if tys.references_error() => tcx.types.err, 0 => tcx.types.bool, 1 => tys[0], _ => tcx.intern_tup(&tys[..]) }; let old = tcx.adt_sized_constraint.borrow().get(&self.did).cloned(); match old { Some(old_ty) => { debug!("calculate_sized_constraint: {:?} recurred", self); assert_eq!(old_ty, tcx.types.err); old_ty } None => { debug!("calculate_sized_constraint: {:?} => {:?}", self, ty); tcx.adt_sized_constraint.borrow_mut().insert(self.did, ty); ty } } } fn sized_constraint_for_ty(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, stack: &mut Vec, ty: Ty<'tcx>) -> Vec> { let result = match ty.sty { TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) | TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) | TyArray(..) | TyClosure(..) | TyNever => { vec![] } TyStr | TyDynamic(..) | TySlice(_) | TyError => { // these are never sized - return the target type vec![ty] } TyTuple(ref tys) => { match tys.last() { None => vec![], Some(ty) => self.sized_constraint_for_ty(tcx, stack, ty) } } TyAdt(adt, substs) => { // recursive case let adt_ty = adt.calculate_sized_constraint_inner(tcx, stack) .subst(tcx, substs); debug!("sized_constraint_for_ty({:?}) intermediate = {:?}", ty, adt_ty); if let ty::TyTuple(ref tys) = adt_ty.sty { tys.iter().flat_map(|ty| { self.sized_constraint_for_ty(tcx, stack, ty) }).collect() } else { self.sized_constraint_for_ty(tcx, stack, adt_ty) } } TyProjection(..) | TyAnon(..) => { // must calculate explicitly. // FIXME: consider special-casing always-Sized projections vec![ty] } TyParam(..) => { // perf hack: if there is a `T: Sized` bound, then // we know that `T` is Sized and do not need to check // it on the impl. let sized_trait = match tcx.lang_items.sized_trait() { Some(x) => x, _ => return vec![ty] }; let sized_predicate = Binder(TraitRef { def_id: sized_trait, substs: tcx.mk_substs_trait(ty, &[]) }).to_predicate(); let predicates = tcx.item_predicates(self.did).predicates; if predicates.into_iter().any(|p| p == sized_predicate) { vec![] } else { vec![ty] } } TyInfer(..) => { bug!("unexpected type `{:?}` in sized_constraint_for_ty", ty) } }; debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result); result } } impl<'a, 'gcx, 'tcx> VariantDef { #[inline] pub fn find_field_named(&self, name: ast::Name) -> Option<&FieldDef> { self.fields.iter().find(|f| f.name == name) } #[inline] pub fn index_of_field_named(&self, name: ast::Name) -> Option { self.fields.iter().position(|f| f.name == name) } #[inline] pub fn field_named(&self, name: ast::Name) -> &FieldDef { self.find_field_named(name).unwrap() } } impl<'a, 'gcx, 'tcx> FieldDef { pub fn ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, subst: &Substs<'tcx>) -> Ty<'tcx> { tcx.item_type(self.did).subst(tcx, subst) } } /// Records the substitutions used to translate the polytype for an /// item into the monotype of an item reference. #[derive(Clone, RustcEncodable, RustcDecodable)] pub struct ItemSubsts<'tcx> { pub substs: &'tcx Substs<'tcx>, } #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] 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<'a, 'tcx> ClosureKind { pub fn trait_did(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> DefId { match *self { ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem), ClosureKind::FnMut => { tcx.require_lang_item(FnMutTraitLangItem) } ClosureKind::FnOnce => { tcx.require_lang_item(FnOnceTraitLangItem) } } } /// 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, } } } impl<'tcx> 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> => { Foo>, Bar, isize } /// [isize] => { [isize], isize } /// ``` pub fn walk(&'tcx self) -> TypeWalker<'tcx> { TypeWalker::new(self) } /// Iterator that walks the immediate children of `self`. Hence /// `Foo, u32>` yields the sequence `[Bar, u32]` /// (but not `i32`, like `walk`). pub fn walk_shallow(&'tcx self) -> AccIntoIter> { walk::walk_shallow(self) } /// Walks `ty` and any types appearing within `ty`, invoking the /// callback `f` on each type. If the callback returns false, then the /// children of the current type are ignored. /// /// Note: prefer `ty.walk()` where possible. pub fn maybe_walk(&'tcx self, mut f: F) where F : FnMut(Ty<'tcx>) -> bool { let mut walker = self.walk(); while let Some(ty) = walker.next() { if !f(ty) { walker.skip_current_subtree(); } } } } impl<'tcx> ItemSubsts<'tcx> { pub fn is_noop(&self) -> bool { self.substs.is_noop() } } #[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum LvaluePreference { PreferMutLvalue, NoPreference } impl LvaluePreference { pub fn from_mutbl(m: hir::Mutability) -> Self { match m { hir::MutMutable => PreferMutLvalue, hir::MutImmutable => NoPreference, } } } /// Helper for looking things up in the various maps that are populated during /// typeck::collect (e.g., `tcx.associated_items`, `tcx.types`, etc). All of /// these share the pattern that if the id is local, it should have been loaded /// into the map by the `typeck::collect` phase. If the def-id is external, /// then we have to go consult the crate loading code (and cache the result for /// the future). fn lookup_locally_or_in_crate_store(descr: &str, def_id: DefId, map: &M, load_external: F) -> M::Value where M: MemoizationMap, F: FnOnce() -> M::Value, { map.memoize(def_id, || { if def_id.is_local() { bug!("No def'n found for {:?} in tcx.{}", def_id, descr); } load_external() }) } impl BorrowKind { pub fn from_mutbl(m: hir::Mutability) -> BorrowKind { match m { hir::MutMutable => MutBorrow, hir::MutImmutable => 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::MutMutable, ImmBorrow => hir::MutImmutable, // 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::MutMutable, } } pub fn to_user_str(&self) -> &'static str { match *self { MutBorrow => "mutable", ImmBorrow => "immutable", UniqueImmBorrow => "uniquely immutable", } } } impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { pub fn body_tables(self, body: hir::BodyId) -> &'gcx TypeckTables<'gcx> { self.item_tables(self.hir.body_owner_def_id(body)) } pub fn item_tables(self, def_id: DefId) -> &'gcx TypeckTables<'gcx> { self.tables.memoize(def_id, || { if def_id.is_local() { // Closures' tables come from their outermost function, // as they are part of the same "inference environment". let outer_def_id = self.closure_base_def_id(def_id); if outer_def_id != def_id { return self.item_tables(outer_def_id); } bug!("No def'n found for {:?} in tcx.tables", def_id); } // Cross-crate side-tables only exist alongside serialized HIR. self.sess.cstore.maybe_get_item_body(self.global_tcx(), def_id).map(|_| { self.tables.borrow()[&def_id] }).unwrap_or_else(|| { bug!("tcx.item_tables({:?}): missing from metadata", def_id) }) }) } pub fn expr_span(self, id: NodeId) -> Span { match self.hir.find(id) { Some(hir_map::NodeExpr(e)) => { e.span } Some(f) => { bug!("Node id {} is not an expr: {:?}", id, f); } None => { bug!("Node id {} is not present in the node map", id); } } } pub fn local_var_name_str(self, id: NodeId) -> InternedString { match self.hir.find(id) { Some(hir_map::NodeLocal(pat)) => { match pat.node { hir::PatKind::Binding(_, _, ref path1, _) => path1.node.as_str(), _ => { bug!("Variable id {} maps to {:?}, not local", id, pat); }, } }, r => bug!("Variable id {} maps to {:?}, not local", id, r), } } pub fn expr_is_lval(self, expr: &hir::Expr) -> bool { match expr.node { hir::ExprPath(hir::QPath::Resolved(_, ref path)) => { match path.def { Def::Local(..) | Def::Upvar(..) | Def::Static(..) | Def::Err => true, _ => false, } } hir::ExprType(ref e, _) => { self.expr_is_lval(e) } hir::ExprUnary(hir::UnDeref, _) | hir::ExprField(..) | hir::ExprTupField(..) | hir::ExprIndex(..) => { true } // Partially qualified paths in expressions can only legally // refer to associated items which are always rvalues. hir::ExprPath(hir::QPath::TypeRelative(..)) | hir::ExprCall(..) | hir::ExprMethodCall(..) | hir::ExprStruct(..) | hir::ExprTup(..) | hir::ExprIf(..) | hir::ExprMatch(..) | hir::ExprClosure(..) | hir::ExprBlock(..) | hir::ExprRepeat(..) | hir::ExprArray(..) | hir::ExprBreak(..) | hir::ExprAgain(..) | hir::ExprRet(..) | hir::ExprWhile(..) | hir::ExprLoop(..) | hir::ExprAssign(..) | hir::ExprInlineAsm(..) | hir::ExprAssignOp(..) | hir::ExprLit(_) | hir::ExprUnary(..) | hir::ExprBox(..) | hir::ExprAddrOf(..) | hir::ExprBinary(..) | hir::ExprCast(..) => { false } } } pub fn provided_trait_methods(self, id: DefId) -> Vec { self.associated_items(id) .filter(|item| item.kind == AssociatedKind::Method && item.defaultness.has_value()) .collect() } pub fn trait_impl_polarity(self, id: DefId) -> hir::ImplPolarity { if let Some(id) = self.hir.as_local_node_id(id) { match self.hir.expect_item(id).node { hir::ItemImpl(_, polarity, ..) => polarity, ref item => bug!("trait_impl_polarity: {:?} not an impl", item) } } else { self.sess.cstore.impl_polarity(id) } } pub fn custom_coerce_unsized_kind(self, did: DefId) -> adjustment::CustomCoerceUnsized { self.custom_coerce_unsized_kinds.memoize(did, || { let (kind, src) = if did.krate != LOCAL_CRATE { (self.sess.cstore.custom_coerce_unsized_kind(did), "external") } else { (None, "local") }; match kind { Some(kind) => kind, None => { bug!("custom_coerce_unsized_kind: \ {} impl `{}` is missing its kind", src, self.item_path_str(did)); } } }) } pub fn associated_item(self, def_id: DefId) -> AssociatedItem { self.associated_items.memoize(def_id, || { if !def_id.is_local() { return self.sess.cstore.associated_item(def_id) .expect("missing AssociatedItem in metadata"); } // When the user asks for a given associated item, we // always go ahead and convert all the associated items in // the container. Note that we are also careful only to // ever register a read on the *container* of the assoc // item, not the assoc item itself. This prevents changes // in the details of an item (for example, the type to // which an associated type is bound) from contaminating // those tasks that just need to scan the names of items // and so forth. let id = self.hir.as_local_node_id(def_id).unwrap(); let parent_id = self.hir.get_parent(id); let parent_def_id = self.hir.local_def_id(parent_id); let parent_item = self.hir.expect_item(parent_id); match parent_item.node { hir::ItemImpl(.., ref impl_trait_ref, _, ref impl_item_refs) => { for impl_item_ref in impl_item_refs { let assoc_item = self.associated_item_from_impl_item_ref(parent_def_id, impl_trait_ref.is_some(), impl_item_ref); self.associated_items.borrow_mut().insert(assoc_item.def_id, assoc_item); } } hir::ItemTrait(.., ref trait_item_refs) => { for trait_item_ref in trait_item_refs { let assoc_item = self.associated_item_from_trait_item_ref(parent_def_id, trait_item_ref); self.associated_items.borrow_mut().insert(assoc_item.def_id, assoc_item); } } ref r => { panic!("unexpected container of associated items: {:?}", r) } } // memoize wants us to return something, so return // the one we generated for this def-id *self.associated_items.borrow().get(&def_id).unwrap() }) } fn associated_item_from_trait_item_ref(self, parent_def_id: DefId, trait_item_ref: &hir::TraitItemRef) -> AssociatedItem { let def_id = self.hir.local_def_id(trait_item_ref.id.node_id); let (kind, has_self) = match trait_item_ref.kind { hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false), hir::AssociatedItemKind::Method { has_self } => { (ty::AssociatedKind::Method, has_self) } hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false), }; AssociatedItem { name: trait_item_ref.name, kind: kind, vis: Visibility::from_hir(&hir::Inherited, trait_item_ref.id.node_id, self), defaultness: trait_item_ref.defaultness, def_id: def_id, container: TraitContainer(parent_def_id), method_has_self_argument: has_self } } fn associated_item_from_impl_item_ref(self, parent_def_id: DefId, from_trait_impl: bool, impl_item_ref: &hir::ImplItemRef) -> AssociatedItem { let def_id = self.hir.local_def_id(impl_item_ref.id.node_id); let (kind, has_self) = match impl_item_ref.kind { hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false), hir::AssociatedItemKind::Method { has_self } => { (ty::AssociatedKind::Method, has_self) } hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false), }; // Trait impl items are always public. let public = hir::Public; let vis = if from_trait_impl { &public } else { &impl_item_ref.vis }; ty::AssociatedItem { name: impl_item_ref.name, kind: kind, vis: ty::Visibility::from_hir(vis, impl_item_ref.id.node_id, self), defaultness: impl_item_ref.defaultness, def_id: def_id, container: ImplContainer(parent_def_id), method_has_self_argument: has_self } } pub fn associated_item_def_ids(self, def_id: DefId) -> Rc> { self.associated_item_def_ids.memoize(def_id, || { if !def_id.is_local() { return Rc::new(self.sess.cstore.associated_item_def_ids(def_id)); } let id = self.hir.as_local_node_id(def_id).unwrap(); let item = self.hir.expect_item(id); let vec: Vec<_> = match item.node { hir::ItemTrait(.., ref trait_item_refs) => { trait_item_refs.iter() .map(|trait_item_ref| trait_item_ref.id) .map(|id| self.hir.local_def_id(id.node_id)) .collect() } hir::ItemImpl(.., ref impl_item_refs) => { impl_item_refs.iter() .map(|impl_item_ref| impl_item_ref.id) .map(|id| self.hir.local_def_id(id.node_id)) .collect() } _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait") }; Rc::new(vec) }) } #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait. pub fn associated_items(self, def_id: DefId) -> impl Iterator + 'a { let def_ids = self.associated_item_def_ids(def_id); (0..def_ids.len()).map(move |i| self.associated_item(def_ids[i])) } /// Returns the trait-ref corresponding to a given impl, or None if it is /// an inherent impl. pub fn impl_trait_ref(self, id: DefId) -> Option> { lookup_locally_or_in_crate_store( "impl_trait_refs", id, &self.impl_trait_refs, || self.sess.cstore.impl_trait_ref(self.global_tcx(), id)) } // Returns `ty::VariantDef` if `def` refers to a struct, // or variant or their constructors, panics otherwise. pub fn expect_variant_def(self, def: Def) -> &'tcx VariantDef { match def { Def::Variant(did) | Def::VariantCtor(did, ..) => { let enum_did = self.parent_def_id(did).unwrap(); self.lookup_adt_def(enum_did).variant_with_id(did) } Def::Struct(did) | Def::Union(did) => { self.lookup_adt_def(did).struct_variant() } Def::StructCtor(ctor_did, ..) => { let did = self.parent_def_id(ctor_did).expect("struct ctor has no parent"); self.lookup_adt_def(did).struct_variant() } _ => bug!("expect_variant_def used with unexpected def {:?}", def) } } pub fn def_key(self, id: DefId) -> hir_map::DefKey { if id.is_local() { self.hir.def_key(id) } else { self.sess.cstore.def_key(id) } } /// Convert a `DefId` into its fully expanded `DefPath` (every /// `DefId` is really just an interned def-path). /// /// 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) -> hir_map::DefPath { if id.is_local() { self.hir.def_path(id) } else { self.sess.cstore.def_path(id) } } pub fn def_span(self, def_id: DefId) -> Span { if let Some(id) = self.hir.as_local_node_id(def_id) { self.hir.span(id) } else { self.sess.cstore.def_span(&self.sess, def_id) } } pub fn vis_is_accessible_from(self, vis: Visibility, block: NodeId) -> bool { vis.is_accessible_from(self.hir.local_def_id(self.hir.get_module_parent(block)), self) } pub fn item_name(self, id: DefId) -> ast::Name { if let Some(id) = self.hir.as_local_node_id(id) { self.hir.name(id) } else if id.index == CRATE_DEF_INDEX { self.sess.cstore.original_crate_name(id.krate) } else { let def_key = self.sess.cstore.def_key(id); // The name of a StructCtor is that of its struct parent. if let hir_map::DefPathData::StructCtor = def_key.disambiguated_data.data { self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() }) } else { def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| { bug!("item_name: no name for {:?}", self.def_path(id)); }) } } } // If the given item is in an external crate, looks up its type and adds it to // the type cache. Returns the type parameters and type. pub fn item_type(self, did: DefId) -> Ty<'gcx> { lookup_locally_or_in_crate_store( "item_types", did, &self.item_types, || self.sess.cstore.item_type(self.global_tcx(), did)) } /// Given the did of a trait, returns its canonical trait ref. pub fn lookup_trait_def(self, did: DefId) -> &'gcx TraitDef { lookup_locally_or_in_crate_store( "trait_defs", did, &self.trait_defs, || self.alloc_trait_def(self.sess.cstore.trait_def(self.global_tcx(), did)) ) } /// Given the did of an ADT, return a reference to its definition. pub fn lookup_adt_def(self, did: DefId) -> &'gcx AdtDef { lookup_locally_or_in_crate_store( "adt_defs", did, &self.adt_defs, || self.sess.cstore.adt_def(self.global_tcx(), did)) } /// Given the did of an item, returns its generics. pub fn item_generics(self, did: DefId) -> &'gcx Generics<'gcx> { lookup_locally_or_in_crate_store( "generics", did, &self.generics, || self.alloc_generics(self.sess.cstore.item_generics(self.global_tcx(), did))) } /// Given the did of an item, returns its full set of predicates. pub fn item_predicates(self, did: DefId) -> GenericPredicates<'gcx> { lookup_locally_or_in_crate_store( "predicates", did, &self.predicates, || self.sess.cstore.item_predicates(self.global_tcx(), did)) } /// Given the did of a trait, returns its superpredicates. pub fn item_super_predicates(self, did: DefId) -> GenericPredicates<'gcx> { lookup_locally_or_in_crate_store( "super_predicates", did, &self.super_predicates, || self.sess.cstore.item_super_predicates(self.global_tcx(), did)) } /// Given the did of an item, returns its MIR, borrowed immutably. pub fn item_mir(self, did: DefId) -> Ref<'gcx, Mir<'gcx>> { lookup_locally_or_in_crate_store("mir_map", did, &self.mir_map, || { let mir = self.sess.cstore.get_item_mir(self.global_tcx(), did); let mir = self.alloc_mir(mir); // Perma-borrow MIR from extern crates to prevent mutation. mem::forget(mir.borrow()); mir }).borrow() } /// If `type_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 `type_needs_drop` will definitely return `true` for `ty`.) pub fn type_needs_drop_given_env(self, ty: Ty<'gcx>, param_env: &ty::ParameterEnvironment<'gcx>) -> bool { // Issue #22536: We first query type_moves_by_default. It sees a // normalized version of the type, and therefore will definitely // know whether the type implements Copy (and thus needs no // cleanup/drop/zeroing) ... let tcx = self.global_tcx(); let implements_copy = !ty.moves_by_default(tcx, param_env, DUMMY_SP); if implements_copy { return false; } // ... (issue #22536 continued) but as an optimization, still use // prior logic of asking if the `needs_drop` bit is set; we need // not zero non-Copy types if they have no destructor. // FIXME(#22815): Note that calling `ty::type_contents` is a // conservative heuristic; it may report that `needs_drop` is set // when actual type does not actually have a destructor associated // with it. But since `ty` absolutely did not have the `Copy` // bound attached (see above), it is sound to treat it as having a // destructor (e.g. zero its memory on move). let contents = ty.type_contents(tcx); debug!("type_needs_drop ty={:?} contents={:?}", ty, contents); contents.needs_drop(tcx) } /// Get the attributes of a definition. pub fn get_attrs(self, did: DefId) -> Cow<'gcx, [ast::Attribute]> { if let Some(id) = self.hir.as_local_node_id(did) { Cow::Borrowed(self.hir.attrs(id)) } else { Cow::Owned(self.sess.cstore.item_attrs(did)) } } /// Determine whether an item is annotated with an attribute pub fn has_attr(self, did: DefId, attr: &str) -> bool { self.get_attrs(did).iter().any(|item| item.check_name(attr)) } /// Determine whether an item is annotated with `#[repr(packed)]` pub fn lookup_packed(self, did: DefId) -> bool { self.lookup_repr_hints(did).contains(&attr::ReprPacked) } /// Determine whether an item is annotated with `#[simd]` pub fn lookup_simd(self, did: DefId) -> bool { self.has_attr(did, "simd") || self.lookup_repr_hints(did).contains(&attr::ReprSimd) } pub fn item_variances(self, item_id: DefId) -> Rc> { lookup_locally_or_in_crate_store( "item_variance_map", item_id, &self.item_variance_map, || Rc::new(self.sess.cstore.item_variances(item_id))) } pub fn trait_has_default_impl(self, trait_def_id: DefId) -> bool { self.populate_implementations_for_trait_if_necessary(trait_def_id); let def = self.lookup_trait_def(trait_def_id); def.flags.get().intersects(TraitFlags::HAS_DEFAULT_IMPL) } /// Records a trait-to-implementation mapping. pub fn record_trait_has_default_impl(self, trait_def_id: DefId) { let def = self.lookup_trait_def(trait_def_id); def.flags.set(def.flags.get() | TraitFlags::HAS_DEFAULT_IMPL) } /// Populates the type context with all the inherent implementations for /// the given type if necessary. pub fn populate_inherent_implementations_for_type_if_necessary(self, type_id: DefId) { if type_id.is_local() { return } // The type is not local, hence we are reading this out of // metadata and don't need to track edges. let _ignore = self.dep_graph.in_ignore(); if self.populated_external_types.borrow().contains(&type_id) { return } debug!("populate_inherent_implementations_for_type_if_necessary: searching for {:?}", type_id); let inherent_impls = self.sess.cstore.inherent_implementations_for_type(type_id); self.inherent_impls.borrow_mut().insert(type_id, inherent_impls); self.populated_external_types.borrow_mut().insert(type_id); } /// Populates the type context with all the implementations for the given /// trait if necessary. pub fn populate_implementations_for_trait_if_necessary(self, trait_id: DefId) { if trait_id.is_local() { return } // The type is not local, hence we are reading this out of // metadata and don't need to track edges. let _ignore = self.dep_graph.in_ignore(); let def = self.lookup_trait_def(trait_id); if def.flags.get().intersects(TraitFlags::IMPLS_VALID) { return; } debug!("populate_implementations_for_trait_if_necessary: searching for {:?}", def); if self.sess.cstore.is_defaulted_trait(trait_id) { self.record_trait_has_default_impl(trait_id); } for impl_def_id in self.sess.cstore.implementations_of_trait(Some(trait_id)) { let trait_ref = self.impl_trait_ref(impl_def_id).unwrap(); // Record the trait->implementation mapping. let parent = self.sess.cstore.impl_parent(impl_def_id).unwrap_or(trait_id); def.record_remote_impl(self, impl_def_id, trait_ref, parent); } def.flags.set(def.flags.get() | TraitFlags::IMPLS_VALID); } pub fn closure_kind(self, def_id: DefId) -> ty::ClosureKind { // If this is a local def-id, it should be inserted into the // tables by typeck; else, it will be retreived from // the external crate metadata. if let Some(&kind) = self.closure_kinds.borrow().get(&def_id) { return kind; } let kind = self.sess.cstore.closure_kind(def_id); self.closure_kinds.borrow_mut().insert(def_id, kind); kind } pub fn closure_type(self, def_id: DefId, substs: ClosureSubsts<'tcx>) -> ty::ClosureTy<'tcx> { // If this is a local def-id, it should be inserted into the // tables by typeck; else, it will be retreived from // the external crate metadata. if let Some(ty) = self.closure_tys.borrow().get(&def_id) { return ty.subst(self, substs.substs); } let ty = self.sess.cstore.closure_ty(self.global_tcx(), def_id); self.closure_tys.borrow_mut().insert(def_id, ty.clone()); ty.subst(self, substs.substs) } /// Given the def_id of an impl, return the def_id of the trait it implements. /// If it implements no trait, return `None`. pub fn trait_id_of_impl(self, def_id: DefId) -> Option { self.impl_trait_ref(def_id).map(|tr| tr.def_id) } /// If the given def ID describes a method belonging to an impl, return the /// ID of the impl that the method belongs to. Otherwise, return `None`. pub fn impl_of_method(self, def_id: DefId) -> Option { if def_id.krate != LOCAL_CRATE { return self.sess.cstore.associated_item(def_id).and_then(|item| { match item.container { TraitContainer(_) => None, ImplContainer(def_id) => Some(def_id), } }); } match self.associated_items.borrow().get(&def_id).cloned() { Some(trait_item) => { match trait_item.container { TraitContainer(_) => None, ImplContainer(def_id) => Some(def_id), } } None => None } } /// If the given def ID describes an item belonging to a trait, /// return the ID of the trait that the trait item belongs to. /// Otherwise, return `None`. pub fn trait_of_item(self, def_id: DefId) -> Option { if def_id.krate != LOCAL_CRATE { return self.sess.cstore.trait_of_item(def_id); } match self.associated_items.borrow().get(&def_id) { Some(associated_item) => { match associated_item.container { TraitContainer(def_id) => Some(def_id), ImplContainer(_) => None } } None => None } } /// Construct a parameter environment suitable for static contexts or other contexts where there /// are no free type/lifetime parameters in scope. pub fn empty_parameter_environment(self) -> ParameterEnvironment<'tcx> { // for an empty parameter environment, there ARE no free // regions, so it shouldn't matter what we use for the free id let free_id_outlive = self.region_maps.node_extent(ast::DUMMY_NODE_ID); ty::ParameterEnvironment { free_substs: self.intern_substs(&[]), caller_bounds: Vec::new(), implicit_region_bound: self.mk_region(ty::ReEmpty), free_id_outlive: free_id_outlive, is_copy_cache: RefCell::new(FxHashMap()), is_sized_cache: RefCell::new(FxHashMap()), } } /// Constructs and returns a substitution that can be applied to move from /// the "outer" view of a type or method to the "inner" view. /// In general, this means converting from bound parameters to /// free parameters. Since we currently represent bound/free type /// parameters in the same way, this only has an effect on regions. pub fn construct_free_substs(self, def_id: DefId, free_id_outlive: CodeExtent) -> &'gcx Substs<'gcx> { let substs = Substs::for_item(self.global_tcx(), def_id, |def, _| { // map bound 'a => free 'a self.global_tcx().mk_region(ReFree(FreeRegion { scope: free_id_outlive, bound_region: def.to_bound_region() })) }, |def, _| { // map T => T self.global_tcx().mk_param_from_def(def) }); debug!("construct_parameter_environment: {:?}", substs); substs } /// See `ParameterEnvironment` struct def'n for details. /// If you were using `free_id: NodeId`, you might try `self.region_maps.item_extent(free_id)` /// for the `free_id_outlive` parameter. (But note that this is not always quite right.) pub fn construct_parameter_environment(self, span: Span, def_id: DefId, free_id_outlive: CodeExtent) -> ParameterEnvironment<'gcx> { // // Construct the free substs. // let free_substs = self.construct_free_substs(def_id, free_id_outlive); // // Compute the bounds on Self and the type parameters. // let tcx = self.global_tcx(); let generic_predicates = tcx.item_predicates(def_id); let bounds = generic_predicates.instantiate(tcx, free_substs); let bounds = tcx.liberate_late_bound_regions(free_id_outlive, &ty::Binder(bounds)); let predicates = bounds.predicates; // Finally, we have to normalize the bounds in the environment, in // case they contain any associated type projections. This process // can yield errors if the put in illegal associated types, like // `::Bar` where `i32` does not implement `Foo`. We // report these errors right here; this doesn't actually feel // right to me, because constructing the environment feels like a // kind of a "idempotent" action, but I'm not sure where would be // a better place. In practice, we construct environments for // every fn once during type checking, and we'll abort if there // are any errors at that point, so after type checking you can be // sure that this will succeed without errors anyway. // let unnormalized_env = ty::ParameterEnvironment { free_substs: free_substs, implicit_region_bound: tcx.mk_region(ty::ReScope(free_id_outlive)), caller_bounds: predicates, free_id_outlive: free_id_outlive, is_copy_cache: RefCell::new(FxHashMap()), is_sized_cache: RefCell::new(FxHashMap()), }; let cause = traits::ObligationCause::misc(span, free_id_outlive.node_id(&self.region_maps)); traits::normalize_param_env_or_error(tcx, unnormalized_env, cause) } pub fn node_scope_region(self, id: NodeId) -> &'tcx Region { self.mk_region(ty::ReScope(self.region_maps.node_extent(id))) } pub fn visit_all_item_likes_in_krate(self, dep_node_fn: F, visitor: &mut V) where F: FnMut(DefId) -> DepNode, V: ItemLikeVisitor<'gcx> { dep_graph::visit_all_item_likes_in_krate(self.global_tcx(), dep_node_fn, visitor); } /// 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 { if impl_did.is_local() { let node_id = self.hir.as_local_node_id(impl_did).unwrap(); Ok(self.hir.span(node_id)) } else { Err(self.sess.cstore.crate_name(impl_did.krate)) } } } impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { pub fn with_freevars(self, fid: NodeId, f: F) -> T where F: FnOnce(&[hir::Freevar]) -> T, { match self.freevars.borrow().get(&fid) { None => f(&[]), Some(d) => f(&d[..]) } } }