[clang] [Clang] disallow constexpr with auto and explicit type in C23 (PR #163469)

[Mariya Podchishchaeva via cfe-commits]

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@@ -271,6 +271,8 @@ Non-comprehensive list of changes in this release
   allocation functions with a token ID can be enabled via the
   ``-fsanitize=alloc-token`` flag.
 
+- Clang now rejects the invalid use of ``constexpr`` with ``auto`` and an explicit type. (#GH163090)
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Fznamznon wrote:

```suggestion
- Clang now rejects the invalid use of ``constexpr`` with ``auto`` and an explicit type in C. (#GH163090)
```

https://github.com/llvm/llvm-project/pull/163469