Rollup merge of #128989 - s7tya:check-linkage-attribute-pos, r=petrochenkov

Emit an error for invalid use of the linkage attribute

fixes #128486

Currently, the use of the linkage attribute for Mod, Impl,... is incorrectly permitted. This PR will correct this issue by generating errors, and I've also added some UI test cases for it.

Related: #128552.

2 files changed, 23 insertions, 1 deletions

diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index bd157d1d619..a47add929eb 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -243,6 +243,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 [sym::coroutine, ..] => {
                     self.check_coroutine(attr, target);
                 }
+                [sym::linkage, ..] => self.check_linkage(attr, span, target),
                 [
                     // ok
                     sym::allow
@@ -256,7 +257,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | sym::cfi_encoding // FIXME(cfi_encoding)
                     | sym::may_dangle // FIXME(dropck_eyepatch)
                     | sym::pointee // FIXME(derive_smart_pointer)
-                    | sym::linkage // FIXME(linkage)
                     | sym::omit_gdb_pretty_printer_section // FIXME(omit_gdb_pretty_printer_section)
                     | sym::used // handled elsewhere to restrict to static items
                     | sym::repr // handled elsewhere to restrict to type decls items
@@ -2347,6 +2347,19 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             }
         }
     }
+
+    fn check_linkage(&self, attr: &Attribute, span: Span, target: Target) {
+        match target {
+            Target::Fn
+            | Target::Method(..)
+            | Target::Static
+            | Target::ForeignStatic
+            | Target::ForeignFn => {}
+            _ => {
+                self.dcx().emit_err(errors::Linkage { attr_span: attr.span, span });
+            }
+        }
+    }
 }
 
 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 36dfc40e762..3a043e0e3c1 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -644,6 +644,15 @@ pub struct CoroutineOnNonClosure {
 }
 
 #[derive(Diagnostic)]
+#[diag(passes_linkage)]
+pub struct Linkage {
+    #[primary_span]
+    pub attr_span: Span,
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(passes_empty_confusables)]
 pub(crate) struct EmptyConfusables {
     #[primary_span]