[clang] Add 'enum_select' diagnostic selection to clang. (PR #122505)

[Aaron Ballman via cfe-commits]

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@@ -1042,6 +1119,9 @@ Piece *DiagnosticTextBuilder::DiagText::parseDiagText(StringRef &Text,
                                 Modifier);
     };
 
+    if (ModType != MT_EnumSelect && Text[0] == '<')
+      Builder.PrintFatalError("modifier '<' syntax not valid with " + Modifier);
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AaronBallman wrote:

Test coverage for this bit?

https://github.com/llvm/llvm-project/pull/122505