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Rollup merge of #125920 - bjorn3:allow_static_mut_linkage_def, r=Urgau

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Allow static mut definitions with #[linkage]

Unlike static declarations with #[linkage], for definitions rustc doesn't rewrite it to add an extra indirection.

This was accidentally disallowed in https://github.com/rust-lang/rust/pull/125046.

cc https://github.com/rust-lang/rust/pull/125800#issuecomment-2143776298
This commit is contained in:
Jubilee 2024-06-05 01:14:32 -07:00 committed by GitHub
commit 2b89c1b9ae
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3 changed files with 30 additions and 20 deletions
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25
compiler/rustc_codegen_ssa/src/codegen_attrs.rs
View File

@ -324,21 +324,22 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
let linkage = Some(linkage_by_name(tcx, did, val.as_str()));
if tcx.is_foreign_item(did) {
codegen_fn_attrs.import_linkage = linkage;
if tcx.is_mutable_static(did.into()) {
let mut diag = tcx.dcx().struct_span_err(
attr.span,
"extern mutable statics are not allowed with `#[linkage]`",
);
diag.note(
"marking the extern static mutable would allow changing which symbol \
the static references rather than make the target of the symbol \
mutable",
);
diag.emit();
}
} else {
codegen_fn_attrs.linkage = linkage;
}
if tcx.is_mutable_static(did.into()) {
let mut diag = tcx.dcx().struct_span_err(
attr.span,
"mutable statics are not allowed with `#[linkage]`",
);
diag.note(
"making the static mutable would allow changing which symbol the \
static references rather than make the target of the symbol \
mutable",
);
diag.emit();
}
}
}
sym::link_section => {

15
tests/ui/linkage-attr/linkage-attr-mutable-static.rs
View File

@ -4,12 +4,21 @@
#![feature(linkage)]
fn main() {
#[rustfmt::skip]
extern "C" {
#[linkage = "weak"] //~ ERROR mutable statics are not allowed with `#[linkage]`
static mut ABC: *const u8;
#[linkage = "extern_weak"] //~ ERROR extern mutable statics are not allowed with `#[linkage]`
static mut EXTERN_WEAK: *const u8;
}
unsafe {
assert_eq!(ABC as usize, 0);
assert_eq!(EXTERN_WEAK as usize, 0);
}
// static mut is fine here as this is a definition rather than declaration.
#[linkage = "weak"]
static mut WEAK_DEF: u8 = 42;
unsafe {
assert_eq!(WEAK_DEF, 0);
}
}

10
tests/ui/linkage-attr/linkage-attr-mutable-static.stderr
View File

@ -1,10 +1,10 @@
error: mutable statics are not allowed with `#[linkage]`
--> $DIR/linkage-attr-mutable-static.rs:8:9
error: extern mutable statics are not allowed with `#[linkage]`
--> $DIR/linkage-attr-mutable-static.rs:9:9
|
LL | #[linkage = "weak"]
| ^^^^^^^^^^^^^^^^^^^
LL | #[linkage = "extern_weak"]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: making the static mutable would allow changing which symbol the static references rather than make the target of the symbol mutable
= note: marking the extern static mutable would allow changing which symbol the static references rather than make the target of the symbol mutable
error: aborting due to 1 previous error