From: Arthur Cohen <[email protected]>
Per Rust's RFC 1861 (https://rust-lang.github.io/rfcs/1861-extern-types.html),
extern types
are FFI-safe types that are dynamically sized, and should thus compile down to
regular empty
types like C's void type. They are to always be used with an indirection, which
means they are
effectively always a regular pointer (not a pointer + metadata like a lot of
pointers in Rust) to
C's void type.
Closes Rust-GCC/gccrs#1922. We eventually need to work on adding checks to
external types, but as
they are currently implemented as types not implementing `Sized`, a lot of
their typechecking
behavior is covered.
gcc/rust/ChangeLog:
* backend/rust-compile-type.cc (TyTyResolveCompile::visit): Change
extern type codegen from
empty struct to the void type node.
---
This change was merged into the gccrs repository and is posted here for
upstream visibility and potential drive-by review, as requested by GCC
release managers.
Each commit email contains a link to its details on github from where you can
find the Pull-Request and associated discussions.
Commit on github:
https://github.com/Rust-GCC/gccrs/commit/930d05a0ec0e0b566bfabf7e931d7e4cff402158
The commit has been mentioned in the following issue(s):
- Rust-GCC/gccrs#1922: https://github.com/Rust-GCC/gccrs/issues/1922
The commit has been mentioned in the following pull-request(s):
- https://github.com/Rust-GCC/gccrs/pull/4834
gcc/rust/backend/rust-compile-type.cc | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/gcc/rust/backend/rust-compile-type.cc
b/gcc/rust/backend/rust-compile-type.cc
index 56f9e9424..4b39a44f1 100644
--- a/gcc/rust/backend/rust-compile-type.cc
+++ b/gcc/rust/backend/rust-compile-type.cc
@@ -344,7 +344,10 @@ TyTyResolveCompile::visit (const TyTy::ADTType &type)
}
else if (type.get_adt_kind () == TyTy::ADTType::ADTKind::EXTERN)
{
- type_record = Backend::struct_type ({});
+ // Extern types are codegen'd as C's void type. They can only be used
+ // through indirection, so they're effectively always codegen'd as
+ // `void *` types.
+ type_record = void_type_node;
}
else if (!type.is_enum ())
{
base-commit: 112b46e3f8e3b81f28e90a7c8ebd1789592d31cb
--
2.55.0
