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| author | bors <bors@rust-lang.org> | 2025-10-02 01:54:48 +0000 |
|---|---|---|
| committer | bors <bors@rust-lang.org> | 2025-10-02 01:54:48 +0000 |
| commit | 42b384ec0dfcd528d99a4db0a337d9188a9eecaa (patch) | |
| tree | 3514e6cac9bc43fb0b255776653d322956ff4b75 /compiler/rustc_codegen_cranelift | |
| parent | 3369e82c6bc03c5cdb66f730dba6f738b74c8e1d (diff) | |
| parent | 413f095a85adb21331f6e64cf030ead124a6ba07 (diff) | |
| download | rust-42b384ec0dfcd528d99a4db0a337d9188a9eecaa.tar.gz rust-42b384ec0dfcd528d99a4db0a337d9188a9eecaa.zip | |
Auto merge of #147055 - beepster4096:subtype_is_not_a_projection, r=lcnr
Turn ProjectionElem::Subtype into CastKind::Subtype I noticed that drop elaboration can't, in general, handle `ProjectionElem::SubType`. It creates a disjoint move path that overlaps with other move paths. (`Subslice` does too, and I'm working on a different PR to make that special case less fragile.) If its skipped and treated as the same move path as its parent then `MovePath.place` has multiple possible projections. (It would probably make sense to remove all `Subtype` projections for the canonical place but it doesn't make sense to have this special case for a problem that doesn't actually occur in real MIR.) The only reason this doesn't break is that `Subtype` is always the sole projection of the local its applied to. For the same reason, it works fine as a `CastKind` so I figured that makes more sense than documenting and validating this hidden invariant. cc rust-lang/rust#112651, rust-lang/rust#133258 r? Icnr (bc you've been the main person dealing with `Subtype` it looks like)
Diffstat (limited to 'compiler/rustc_codegen_cranelift')
| -rw-r--r-- | compiler/rustc_codegen_cranelift/src/base.rs | 4 | ||||
| -rw-r--r-- | compiler/rustc_codegen_cranelift/src/value_and_place.rs | 2 |
2 files changed, 3 insertions, 3 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs index 2cc5b82ddd3..ebf2ccf74de 100644 --- a/compiler/rustc_codegen_cranelift/src/base.rs +++ b/compiler/rustc_codegen_cranelift/src/base.rs @@ -789,7 +789,7 @@ fn codegen_stmt<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, cur_block: Block, stmt: let operand = codegen_operand(fx, operand); crate::unsize::coerce_unsized_into(fx, operand, lval); } - Rvalue::Cast(CastKind::Transmute, ref operand, _to_ty) => { + Rvalue::Cast(CastKind::Transmute | CastKind::Subtype, ref operand, _to_ty) => { let operand = codegen_operand(fx, operand); lval.write_cvalue_transmute(fx, operand); } @@ -996,7 +996,7 @@ pub(crate) fn codegen_place<'tcx>( cplace = cplace.place_deref(fx); } PlaceElem::OpaqueCast(ty) => bug!("encountered OpaqueCast({ty}) in codegen"), - PlaceElem::Subtype(ty) | PlaceElem::UnwrapUnsafeBinder(ty) => { + PlaceElem::UnwrapUnsafeBinder(ty) => { cplace = cplace.place_transmute_type(fx, fx.monomorphize(ty)); } PlaceElem::Field(field, _ty) => { diff --git a/compiler/rustc_codegen_cranelift/src/value_and_place.rs b/compiler/rustc_codegen_cranelift/src/value_and_place.rs index 04e10cf1708..db9b80c0f6a 100644 --- a/compiler/rustc_codegen_cranelift/src/value_and_place.rs +++ b/compiler/rustc_codegen_cranelift/src/value_and_place.rs @@ -660,7 +660,7 @@ impl<'tcx> CPlace<'tcx> { } } - /// Used for `ProjectionElem::Subtype`, `ty` has to be monomorphized before + /// Used for `ProjectionElem::UnwrapUnsafeBinder`, `ty` has to be monomorphized before /// passed on. pub(crate) fn place_transmute_type( self, |