Assert that all attributes are actually checked via CheckAttrVisitor and aren't accidentally usable on completely unrelated HIR nodes

Co-authored-by: Jieyou Xu <jieyouxu@outlook.com>

compiler/rustc_passes/src/errors.rs

@@ -636,6 +636,13 @@ pub struct Confusables {
     pub attr_span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(passes_coroutine_on_non_closure)]
+pub struct CoroutineOnNonClosure {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(passes_empty_confusables)]
 pub(crate) struct EmptyConfusables {