[clang] [Clang] prevent setting default lexical access specifier for missing primary declarations (PR #112424)

[Shafik Yaghmour via cfe-commits]

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@@ -17957,6 +17957,8 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
             << Name;
         Invalid = true;
       }
+      if (TUK == TagUseKind::Declaration && Name)
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shafik wrote:

Why do we need to check `Name` as well?

https://github.com/llvm/llvm-project/pull/112424