#[repr(transparent)] initial implementation#4650
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gcc/rust/ChangeLog: * typecheck/rust-tyty.h (TyTy::ADTType::ReprKind): Add TRANSPARENT variant. * typecheck/rust-hir-type-check-base.cc (TypeCheckBase::parse_repr_options): Add parsing of transparent repr, throw error for invalid repr. * typecheck/rust-hir-type-check-item.cc (TypeCheckItem::visit (StructStruct)): Throw error if #[repr(transparent)] struct/enum has more than 1 field. Signed-Off-By: Yap Zhi Heng <yapzhhg@gmail.com>
gcc/rust/ChangeLog: * backend/rust-compile-expr.h (CompileExpr::compile_transparent_field_access): New helper function. * backend/rust-compile-expr.cc (CompileExpr::compile_transparent_field_access): Implement helper function for accessing the field of #[repr(transparent)] ADTs. (CompileExpr::visit (HIR::StructExprStructFields)): Support struct field construction properly for #[repr(transparent)] structs. (CompileExpr::visit (HIR::FieldAccessExpr)): Implement proper compilation of field access for #[repr(transparent)] ADTs. * backend/rust-compile-type.cc (TyTyResolveCompile::visit (TyTy::ADTType)): Implement proper compilation of typing for #[repr(transparent)] ADTs. Signed-Off-By: Yap Zhi Heng <yapzhhg@gmail.com>
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rust-lang/rust#77841 Seems like at most one field can be non-1-ZST (zero sized type with alignment 1). That non-1-ZST type can itself be a ZST. If there are no non-1-ZST types, it acts like Also, it looks like much more recent versions of rustc warn/error when the user tries to rely on certain types being 1-ZSTs. I'd figure that could be left for later though. |
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This is needed for for #4565, because#4565 got merged, this PR will also include a fix for a mistake I made there.CStris implemented with#[repr(transparent)]attribute.Note 1: Type-checking doesn't support extra zero-sized members yet, e.g.
Uniquestruct incore/src/ptr/unique.rs:I can open an issue for this after this gets merged.
Note 2: I need someone who's more experienced in Rust to confirm the behavior of transparent structs with 0 fields, since 0-field transparent structs are present in both
coreandkernel. Added a comment regarding in my commit that for now.