[clang] [clang] Fix ASTWriter crash after merging named enums (PR #114240)

[Vassil Vassilev via cfe-commits]

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@@ -2639,6 +2628,19 @@ void Sema::MergeTypedefNameDecl(Scope *S, TypedefNameDecl *New,
   notePreviousDefinition(Old, New->getLocation());
 }
 
+void Sema::CleanupMergedEnum(Scope *S, Decl *New) {
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vgvassilev wrote:

I feel like this is a property of merging. Can we find a common path when merging definitions to put that logic there? Is `MergeTypedefNameDecl` not called for the motivating example?

https://github.com/llvm/llvm-project/pull/114240