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

[via cfe-commits]

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@@ -5360,7 +5360,8 @@ void Parser::ParseEnumBody(SourceLocation StartLoc, Decl *EnumDecl,
   T.consumeOpen();
 
   // C does not allow an empty enumerator-list, C++ does [dcl.enum].
-  if (Tok.is(tok::r_brace) && !getLangOpts().CPlusPlus)
+  if (Tok.is(tok::r_brace) && !getLangOpts().CPlusPlus &&
+      !getLangOpts().MSVCCompat && !getLangOpts().MicrosoftExt)
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yronglin wrote:

IIUC, seems `MSVCCompat` and `MicrosoftExt` are different, even if `MSVCCompat` is `true`, without `-fms-extensions` option, `MicrosoftExt` is still `false` here.

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