diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs | 174 |
1 files changed, 6 insertions, 168 deletions
diff --git a/compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs b/compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs index e3260e45bc5..7d77fffa83f 100644 --- a/compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs +++ b/compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs @@ -6,7 +6,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_data_structures::unord::{UnordMap, UnordSet}; use rustc_errors::Subdiagnostic; use rustc_hir::CRATE_HIR_ID; -use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_hir::def_id::LocalDefId; use rustc_index::bit_set::MixedBitSet; use rustc_index::{IndexSlice, IndexVec}; use rustc_macros::{LintDiagnostic, Subdiagnostic}; @@ -15,7 +15,10 @@ use rustc_middle::mir::{ self, BasicBlock, Body, ClearCrossCrate, Local, Location, Place, StatementKind, TerminatorKind, dump_mir, }; -use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_middle::ty::significant_drop_order::{ + extract_component_with_significant_dtor, ty_dtor_span, +}; +use rustc_middle::ty::{self, TyCtxt}; use rustc_mir_dataflow::impls::MaybeInitializedPlaces; use rustc_mir_dataflow::move_paths::{LookupResult, MoveData, MovePathIndex}; use rustc_mir_dataflow::{Analysis, MaybeReachable, ResultsCursor}; @@ -23,8 +26,7 @@ use rustc_session::lint::builtin::TAIL_EXPR_DROP_ORDER; use rustc_session::lint::{self}; use rustc_span::{DUMMY_SP, Span, Symbol}; use rustc_type_ir::data_structures::IndexMap; -use smallvec::{SmallVec, smallvec}; -use tracing::{debug, instrument}; +use tracing::debug; fn place_has_common_prefix<'tcx>(left: &Place<'tcx>, right: &Place<'tcx>) -> bool { left.local == right.local @@ -155,170 +157,6 @@ impl<'a, 'mir, 'tcx> DropsReachable<'a, 'mir, 'tcx> { } } -/// An additional filter to exclude well-known types from the ecosystem -/// because their drops are trivial. -/// This returns additional types to check if the drops are delegated to those. -/// A typical example is `hashbrown::HashMap<K, V>`, whose drop is delegated to `K` and `V`. -fn true_significant_drop_ty<'tcx>( - tcx: TyCtxt<'tcx>, - ty: Ty<'tcx>, -) -> Option<SmallVec<[Ty<'tcx>; 2]>> { - if let ty::Adt(def, args) = ty.kind() { - let mut did = def.did(); - let mut name_rev = vec![]; - loop { - let key = tcx.def_key(did); - - match key.disambiguated_data.data { - rustc_hir::definitions::DefPathData::CrateRoot => { - name_rev.push(tcx.crate_name(did.krate)) - } - rustc_hir::definitions::DefPathData::TypeNs(symbol) => name_rev.push(symbol), - _ => return None, - } - if let Some(parent) = key.parent { - did = DefId { krate: did.krate, index: parent }; - } else { - break; - } - } - let name_str: Vec<_> = name_rev.iter().rev().map(|x| x.as_str()).collect(); - debug!(?name_str); - match name_str[..] { - // These are the types from Rust core ecosystem - ["syn" | "proc_macro2", ..] - | ["core" | "std", "task", "LocalWaker" | "Waker"] - | ["core" | "std", "task", "wake", "LocalWaker" | "Waker"] => Some(smallvec![]), - // These are important types from Rust ecosystem - ["tracing", "instrument", "Instrumented"] | ["bytes", "Bytes"] => Some(smallvec![]), - ["hashbrown", "raw", "RawTable" | "RawIntoIter"] => { - if let [ty, ..] = &***args - && let Some(ty) = ty.as_type() - { - Some(smallvec![ty]) - } else { - None - } - } - ["hashbrown", "raw", "RawDrain"] => { - if let [_, ty, ..] = &***args - && let Some(ty) = ty.as_type() - { - Some(smallvec![ty]) - } else { - None - } - } - _ => None, - } - } else { - None - } -} - -/// Returns the list of types with a "potentially sigificant" that may be dropped -/// by dropping a value of type `ty`. -#[instrument(level = "debug", skip(tcx, typing_env))] -fn extract_component_raw<'tcx>( - tcx: TyCtxt<'tcx>, - typing_env: ty::TypingEnv<'tcx>, - ty: Ty<'tcx>, - ty_seen: &mut UnordSet<Ty<'tcx>>, -) -> SmallVec<[Ty<'tcx>; 4]> { - // Droppiness does not depend on regions, so let us erase them. - let ty = tcx.try_normalize_erasing_regions(typing_env, ty).unwrap_or(ty); - - let tys = tcx.list_significant_drop_tys(typing_env.as_query_input(ty)); - debug!(?ty, "components"); - let mut out_tys = smallvec![]; - for ty in tys { - if let Some(tys) = true_significant_drop_ty(tcx, ty) { - // Some types can be further opened up because the drop is simply delegated - for ty in tys { - if ty_seen.insert(ty) { - out_tys.extend(extract_component_raw(tcx, typing_env, ty, ty_seen)); - } - } - } else { - if ty_seen.insert(ty) { - out_tys.push(ty); - } - } - } - out_tys -} - -#[instrument(level = "debug", skip(tcx, typing_env))] -fn extract_component_with_significant_dtor<'tcx>( - tcx: TyCtxt<'tcx>, - typing_env: ty::TypingEnv<'tcx>, - ty: Ty<'tcx>, -) -> SmallVec<[Ty<'tcx>; 4]> { - let mut tys = extract_component_raw(tcx, typing_env, ty, &mut Default::default()); - let mut deduplicate = FxHashSet::default(); - tys.retain(|oty| deduplicate.insert(*oty)); - tys.into_iter().collect() -} - -/// Extract the span of the custom destructor of a type -/// especially the span of the `impl Drop` header or its entire block -/// when we are working with current local crate. -#[instrument(level = "debug", skip(tcx))] -fn ty_dtor_span<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Option<Span> { - match ty.kind() { - ty::Bool - | ty::Char - | ty::Int(_) - | ty::Uint(_) - | ty::Float(_) - | ty::Error(_) - | ty::Str - | ty::Never - | ty::RawPtr(_, _) - | ty::Ref(_, _, _) - | ty::FnPtr(_, _) - | ty::Tuple(_) - | ty::Dynamic(_, _, _) - | ty::Alias(_, _) - | ty::Bound(_, _) - | ty::Pat(_, _) - | ty::Placeholder(_) - | ty::Infer(_) - | ty::Slice(_) - | ty::Array(_, _) - | ty::UnsafeBinder(_) => None, - - ty::Adt(adt_def, _) => { - let did = adt_def.did(); - let try_local_did_span = |did: DefId| { - if let Some(local) = did.as_local() { - tcx.source_span(local) - } else { - tcx.def_span(did) - } - }; - let dtor = if let Some(dtor) = tcx.adt_destructor(did) { - dtor.did - } else if let Some(dtor) = tcx.adt_async_destructor(did) { - dtor.future - } else { - return Some(try_local_did_span(did)); - }; - let def_key = tcx.def_key(dtor); - let Some(parent_index) = def_key.parent else { return Some(try_local_did_span(dtor)) }; - let parent_did = DefId { index: parent_index, krate: dtor.krate }; - Some(try_local_did_span(parent_did)) - } - ty::Coroutine(did, _) - | ty::CoroutineWitness(did, _) - | ty::CoroutineClosure(did, _) - | ty::Closure(did, _) - | ty::FnDef(did, _) - | ty::Foreign(did) => Some(tcx.def_span(did)), - ty::Param(_) => None, - } -} - /// Check if a moved place at `idx` is a part of a BID. /// The use of this check is that we will consider drops on these /// as a drop of the overall BID and, thus, we can exclude it from the diagnosis. |