[clang] [Clang] disallow # operators in attribute argument lists (PR #147308)

[Oleksandr T. via cfe-commits]

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@@ -477,3 +477,8 @@ namespace P2361 {
 }
 
 alignas(int) struct AlignAsAttribute {}; // expected-error {{misplaced attributes; expected attributes here}}
+
+namespace GH147217 {
+  [[clang::annotate(#)]] void a();      // expected-error {{'#' is not allowed in attribute argument lists}}
+  [[clang::annotate(##)]] void b();     // expected-error {{'##' is not allowed in attribute argument lists}}
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a-tarasyuk wrote:

@cor3ntin Thanks for the feedback. I've added additional tests

https://github.com/llvm/llvm-project/pull/147308