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

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@@ -276,6 +276,10 @@ def err_expected_while : Error<"expected 'while' in do/while loop">;
 
 def err_expected_semi_after_stmt : Error<"expected ';' after %0 statement">;
 def err_expected_semi_after_expr : Error<"expected ';' after expression">;
+def warn_expected_stmt_before_semi_in_secondary_block : Warning<
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yronglin wrote:

SGTM.

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