optimize attribute applied to things other than methods/functions/closures gives an error (#128488)

Author: tnuha

compiler/rustc_passes/src/check_attr.rs

@@ -124,7 +124,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 }
                 [sym::inline, ..] => self.check_inline(hir_id, attr, span, target),
                 [sym::coverage, ..] => self.check_coverage(attr, span, target),
-                [sym::optimize, ..] => self.check_optimize(hir_id, attr, target),
+                [sym::optimize, ..] => self.check_optimize(hir_id, attr, span, target),
                 [sym::no_sanitize, ..] => self.check_no_sanitize(hir_id, attr, span, target),
                 [sym::non_exhaustive, ..] => self.check_non_exhaustive(hir_id, attr, span, target),
                 [sym::marker, ..] => self.check_marker(hir_id, attr, span, target),
@@ -432,22 +432,21 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     /// Checks that `#[optimize(..)]` is applied to a function/closure/method,
     /// or to an impl block or module.
     // FIXME(#128488): this should probably be elevated to an error?
-    fn check_optimize(&self, hir_id: HirId, attr: &Attribute, target: Target) {
-        match target {
+    fn check_optimize(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
+        let is_valid = matches!(
+            target,
             Target::Fn
-            | Target::Closure
-            | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent)
-            | Target::Impl
-            | Target::Mod => {}
-
-            _ => {
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr.span,
-                    errors::OptimizeNotFnOrClosure,
-                );
-            }
+                | Target::Closure
+                | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent)
+                | Target::Impl
+                | Target::Mod
+        );
+        if !is_valid {
+            self.dcx().emit_err(errors::OptimizeNotFnOrClosure {
+                attr_span: attr.span,
+                defn_span: span,
+                on_crate: hir_id == CRATE_HIR_ID,
+            });
         }
     }
 

compiler/rustc_passes/src/errors.rs

@@ -68,9 +68,15 @@ pub struct CoverageNotFnOrClosure {
     pub defn_span: Span,
 }
 
-#[derive(LintDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(passes_optimize_not_fn_or_closure)]
-pub struct OptimizeNotFnOrClosure;
+pub struct OptimizeNotFnOrClosure {
+    #[primary_span]
+    pub attr_span: Span,
+    #[label]
+    pub defn_span: Span,
+    pub on_crate: bool,
+}
 
 #[derive(Diagnostic)]
 #[diag(passes_should_be_applied_to_fn)]

tests/ui/attributes/optimize.stderr

@@ -3,18 +3,18 @@ error: attribute should be applied to function or closure
    |
 LL | #[optimize(speed)]
    | ^^^^^^^^^^^^^^^^^^
-   |
-note: the lint level is defined here
-  --> $DIR/optimize.rs:3:9
-   |
-LL | #![deny(unused_attributes)]
-   |         ^^^^^^^^^^^^^^^^^
+LL | struct F;
+   | --------- not a function or closure
 
 error: attribute should be applied to function or closure
   --> $DIR/optimize.rs:10:5
    |
-LL |     #[optimize(speed)]
-   |     ^^^^^^^^^^^^^^^^^^
+LL |       #[optimize(speed)]
+   |       ^^^^^^^^^^^^^^^^^^
+LL | /     {
+LL | |         1
+LL | |     };
+   | |_____- not a function or closure
 
 error: aborting due to 2 previous errors