[clang] [clang] Accept empty enum in MSVC compatible C (PR #159981)

[Erich Keane via cfe-commits]

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@@ -380,6 +380,7 @@ Bug Fixes in This Version
   a function without arguments caused us to try to access a non-existent argument.
   (#GH159080)
 - Fixed a failed assertion with empty filename arguments in ``__has_embed``. (#GH159898)
+- Accept empty enum in MSVC-compatible C. (#GH114402)
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erichkeane wrote:

```suggestion
- Accept empty enumerations in MSVC-compatible C mode. (#GH114402)
```

https://github.com/llvm/llvm-project/pull/159981