Reject #[thread_local] attribute on non-static items

compiler/rustc_passes/src/check_attr.rs

@@ -80,6 +80,7 @@ impl CheckAttrVisitor<'_> {
  self.check_rustc_must_implement_one_of(attr, span, target)
  }
  sym::target_feature => self.check_target_feature(hir_id, attr, span, target),
+ sym::thread_local => self.check_thread_local(attr, span, target),
  sym::track_caller => {
  self.check_track_caller(hir_id, attr.span, attrs, span, target)
  }
@@ -521,6 +522,21 @@ impl CheckAttrVisitor<'_> {
  }
  }
 
+ /// Checks if the `#[thread_local]` attribute on `item` is valid. Returns `true` if valid.
+ fn check_thread_local(&self, attr: &Attribute, span: Span, target: Target) -> bool {
+ match target {
+ Target::ForeignStatic | Target::Static => true,
+ _ => {
+ self.tcx
+ .sess
+ .struct_span_err(attr.span, "attribute should be applied to a static")
+ .span_label(span, "not a static")
+ .emit();
+ false
+ }
+ }
+ }
+
  fn doc_attr_str_error(&self, meta: &NestedMetaItem, attr_name: &str) {
  self.tcx
  .sess

src/test/ui/thread-local/non-static.rs

@@ -0,0 +1,30 @@
+// Check that #[thread_local] attribute is rejected on non-static items.
+#![feature(thread_local)]
+
+#[thread_local]
+//~^ ERROR attribute should be applied to a static
+const A: u32 = 0;
+
+#[thread_local]
+//~^ ERROR attribute should be applied to a static
+fn main() {
+ #[thread_local] || {};
+ //~^ ERROR attribute should be applied to a static
+}
+
+struct S {
+ #[thread_local]
+ //~^ ERROR attribute should be applied to a static
+ a: String,
+ b: String,
+}
+
+#[thread_local]
+// Static. OK.
+static B: u32 = 0;
+
+extern "C" {
+ #[thread_local]
+ // Foreign static. OK.
+ static C: u32;
+}

src/test/ui/thread-local/non-static.stderr

@@ -0,0 +1,38 @@
+error: attribute should be applied to a static
+ --> $DIR/non-static.rs:4:1
+ |
+LL | #[thread_local]
+ | ^^^^^^^^^^^^^^^
+LL |
+LL | const A: u32 = 0;
+ | ----------------- not a static
+
+error: attribute should be applied to a static
+ --> $DIR/non-static.rs:8:1
+ |
+LL | #[thread_local]
+ | ^^^^^^^^^^^^^^^
+LL |
+LL | / fn main() {
+LL | | #[thread_local] || {};
+LL | |
+LL | | }
+ | |_- not a static
+
+error: attribute should be applied to a static
+ --> $DIR/non-static.rs:11:5
+ |
+LL | #[thread_local] || {};
+ | ^^^^^^^^^^^^^^^ ----- not a static
+
+error: attribute should be applied to a static
+ --> $DIR/non-static.rs:16:5
+ |
+LL | #[thread_local]
+ | ^^^^^^^^^^^^^^^
+LL |
+LL | a: String,
+ | --------- not a static
+
+error: aborting due to 4 previous errors
+