[clang] Support [[guarded_by(mutex)]] attribute inside C struct (PR #94216)

[Dan Liew via cfe-commits]

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@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -Wthread-safety -Wthread-safety-beta %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wthread-safety -Wthread-safety-beta -fexperimental-late-parse-attributes %s
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delcypher wrote:

@pdherbemont We should probably have a test case that runs without `-fexperimental-late-parse-attributes` so that we check normal parsing still works, especially given that its the default.

https://github.com/llvm/llvm-project/pull/94216