[clang] [Clang] Improve error recovery for indexed template names (PR #222328)

[Shafik Yaghmour via cfe-commits]

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@@ -1266,7 +1300,7 @@ bool Parser::AnnotatePackIndexingTemplateName(CXXScopeSpec &SS,
   Tok.setLocation(NameLoc);
   Tok.setAnnotationEndLoc(T.getCloseLocation());
   PP.AnnotateCachedTokens(Tok);
-  return false;
+  return Indexed.isNull();
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shafik wrote:

Do the tests below cover both `true` and `false` case here?

https://github.com/llvm/llvm-project/pull/222328