[clang] [clang] Substitute alias templates from correct context (PR #74335)

[Erich Keane via cfe-commits]

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@@ -3990,9 +3990,14 @@ QualType Sema::CheckTemplateIdType(TemplateName Name,
     if (Inst.isInvalid())
       return QualType();
 
-    CanonType = SubstType(Pattern->getUnderlyingType(),
-                          TemplateArgLists, AliasTemplate->getLocation(),
-                          AliasTemplate->getDeclName());
+    bool ForLambdaCallOperator = false;
+    if (const auto *Rec = dyn_cast<CXXRecordDecl>(Pattern->getDeclContext()))
+      ForLambdaCallOperator = Rec->isLambda();
+    Sema::ContextRAII SavedContext(*this, Pattern->getDeclContext(),
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erichkeane wrote:

This is supposed to apply only to the SubstType, right?  Probably want a set of braces around it.

https://github.com/llvm/llvm-project/pull/74335