[clang] [C23][Parser] Diagnostic for attribute declaration where statement is required (PR #146224)

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@@ -35,7 +36,7 @@ void f(int n) {
       [[fallthrough]];
     }
   case 8:
-    [[fallthrough]]; // expected-error {{does not directly precede switch label}}
+    [[fallthrough]]; // FIXME: The error {{does not directly precede switch label}} cannot reproduce in this translate unit, But it can be reproduced in a separate file.
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yronglin wrote:

Fixed, it has the same reason as above.

https://github.com/llvm/llvm-project/pull/146224