[clang] [Clang][Sema] Use correct TemplateName when transforming TemplateSpecializationType (PR #93411)

[Younan Zhang via cfe-commits]

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@@ -7216,9 +7216,30 @@ TreeTransform<Derived>::TransformElaboratedType(TypeLocBuilder &TLB,
       return QualType();
   }
 
-  QualType NamedT = getDerived().TransformType(TLB, TL.getNamedTypeLoc());
-  if (NamedT.isNull())
-    return QualType();
+  QualType NamedT;
+  if (SemaRef.getLangOpts().CPlusPlus20 && QualifierLoc &&
+      isa<TemplateSpecializationType>(TL.getNamedTypeLoc().getType())) {
+    TemplateSpecializationTypeLoc SpecTL =
+        TL.getNamedTypeLoc().castAs<TemplateSpecializationTypeLoc>();
+    const TemplateSpecializationType *TST =
+        SpecTL.getType()->castAs<TemplateSpecializationType>();
+    CXXScopeSpec SS;
+    SS.Adopt(QualifierLoc);
+    if (TemplateDecl *TD = TST->getTemplateName().getAsTemplateDecl()) {
+      TemplateName InstName = getDerived().RebuildTemplateName(
+          SS, TL.getTemplateKeywordLoc(), *TD->getIdentifier(),
+          TL.getNamedTypeLoc().getBeginLoc(), /*ObjectType=*/QualType(),
+          /*FirstQualifierInScope=*/nullptr, /*AllowInjectedClassName=*/false);
+      if (InstName.isNull())
+        return QualType();
+      NamedT = TransformTemplateSpecializationType(TLB, SpecTL, InstName);
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zyn0217 wrote:

Did you mean `getDerived().TransformTemplateSpecializationType()`?

https://github.com/llvm/llvm-project/pull/93411