[clang] [Clang][Sema] Allow access to a public template alias declaration that refers to friend's private nested type (PR #83847)

[Qizhi Hu via cfe-commits]

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@@ -4342,10 +4342,17 @@ QualType Sema::CheckTemplateIdType(TemplateName Name,
     InstantiatingTemplate Inst(*this, TemplateLoc, Template);
     if (Inst.isInvalid())
       return QualType();
+    if (!AliasTemplate->getDeclContext()->isFileContext()) {
+      ContextRAII SavedContext(*this, AliasTemplate->getDeclContext());
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jcsxky wrote:

Looks more clear. Thanks for your guidance!

https://github.com/llvm/llvm-project/pull/83847