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

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

1 files changed, 13 insertions, 12 deletions

diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
index 5d7257b15c4..15955170e87 100644
--- a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
+++ b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -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 => {