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Auto merge of #96359 - SparrowLii:drop_kind, r=oli-obk

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make `classify_drop_access_kind` iterate

This PR:
1. fixes the FIXME of `classify_drop_access_kind` func in the borrowck part. The process of obtaining `StorageDeadOrDrop` has been changed from recursive to iterative.
2. gets `place_ty` in each iteration, avoid repeatedly getting the `ty` of the same place (O(n^2) => O(n))
This commit is contained in:
bors 2022-04-24 12:58:16 +00:00
commit d8e59edbfa
1 changed files with 38 additions and 35 deletions
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73
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
View file

@ -7,6 +7,7 @@ use rustc_hir::def_id::DefId;
use rustc_hir::{AsyncGeneratorKind, GeneratorKind};
use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::traits::ObligationCause;
use rustc_middle::mir::tcx::PlaceTy;
use rustc_middle::mir::{
self, AggregateKind, BindingForm, BorrowKind, ClearCrossCrate, ConstraintCategory,
FakeReadCause, LocalDecl, LocalInfo, LocalKind, Location, Operand, Place, PlaceRef,
@ -22,6 +23,7 @@ use rustc_trait_selection::traits::TraitEngineExt as _;
use crate::borrow_set::TwoPhaseActivation;
use crate::borrowck_errors;
use crate::diagnostics::conflict_errors::StorageDeadOrDrop::LocalStorageDead;
use crate::diagnostics::find_all_local_uses;
use crate::{
borrow_set::BorrowData, diagnostics::Instance, prefixes::IsPrefixOf,
@ -1956,45 +1958,46 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
fn classify_drop_access_kind(&self, place: PlaceRef<'tcx>) -> StorageDeadOrDrop<'tcx> {
let tcx = self.infcx.tcx;
match place.last_projection() {
None => StorageDeadOrDrop::LocalStorageDead,
Some((place_base, elem)) => {
// FIXME(spastorino) make this iterate
let base_access = self.classify_drop_access_kind(place_base);
match elem {
ProjectionElem::Deref => match base_access {
StorageDeadOrDrop::LocalStorageDead
| StorageDeadOrDrop::BoxedStorageDead => {
assert!(
place_base.ty(self.body, tcx).ty.is_box(),
"Drop of value behind a reference or raw pointer"
);
StorageDeadOrDrop::BoxedStorageDead
}
StorageDeadOrDrop::Destructor(_) => base_access,
},
ProjectionElem::Field(..) | ProjectionElem::Downcast(..) => {
let base_ty = place_base.ty(self.body, tcx).ty;
match base_ty.kind() {
ty::Adt(def, _) if def.has_dtor(tcx) => {
// Report the outermost adt with a destructor
match base_access {
StorageDeadOrDrop::Destructor(_) => base_access,
StorageDeadOrDrop::LocalStorageDead
| StorageDeadOrDrop::BoxedStorageDead => {
StorageDeadOrDrop::Destructor(base_ty)
let (kind, _place_ty) = place.projection.iter().fold(
(LocalStorageDead, PlaceTy::from_ty(self.body.local_decls[place.local].ty)),
|(kind, place_ty), &elem| {
(
match elem {
ProjectionElem::Deref => match kind {
StorageDeadOrDrop::LocalStorageDead
| StorageDeadOrDrop::BoxedStorageDead => {
assert!(
place_ty.ty.is_box(),
"Drop of value behind a reference or raw pointer"
);
StorageDeadOrDrop::BoxedStorageDead
}
StorageDeadOrDrop::Destructor(_) => kind,
},
ProjectionElem::Field(..) | ProjectionElem::Downcast(..) => {
match place_ty.ty.kind() {
ty::Adt(def, _) if def.has_dtor(tcx) => {
// Report the outermost adt with a destructor
match kind {
StorageDeadOrDrop::Destructor(_) => kind,
StorageDeadOrDrop::LocalStorageDead
| StorageDeadOrDrop::BoxedStorageDead => {
StorageDeadOrDrop::Destructor(place_ty.ty)
}
}
}
_ => kind,
}
_ => base_access,
}
}
ProjectionElem::ConstantIndex { .. }
| ProjectionElem::Subslice { .. }
| ProjectionElem::Index(_) => base_access,
}
}
}
ProjectionElem::ConstantIndex { .. }
| ProjectionElem::Subslice { .. }
| ProjectionElem::Index(_) => kind,
},
place_ty.projection_ty(tcx, elem),
)
},
);
kind
}
/// Describe the reason for the fake borrow that was assigned to `place`.