[clang] [clang] Improve `_Alignas` on a `struct` declaration diagnostic (PR #65638)

[Aaron Ballman via cfe-commits]

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@@ -451,3 +451,5 @@ namespace P2361 {
                                  // expected-warning {{use of the 'deprecated' attribute is a C++14 extension}}
 [[nodiscard("\123")]] int b(); // expected-error{{invalid escape sequence '\123' in an unevaluated string literal}}
 }
+
+alignas(int) struct AlignAsAttribute {}; // expected-error {{misplaced attributes; expected attributes here}}
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AaronBallman wrote:

Note to other reviewers, this C++ test exhibits the same behavior on trunk already: https://godbolt.org/z/s5T3hfxsr

https://github.com/llvm/llvm-project/pull/65638