From 72cf16f31dc2881cc2e54f08b250c17f7c1ad0a7 Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizvekov@gmail.com>
Date: Fri, 15 Aug 2025 16:41:39 -0300
Subject: [PATCH] [clang] fix DependentNameType -> UnresolvedUsingType
 transforms

This fixes a regression reported here https://github.com/llvm/llvm-project/pull/147835#issuecomment-3192237099

Since this regression was never released, there are no release notes.
---
 clang/lib/Sema/TreeTransform.h              | 5 ++++-
 clang/test/SemaCXX/using-decl-templates.cpp | 8 ++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 1863e7f97e3f1..055d3cd1a8609 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -7668,8 +7668,11 @@ QualType TreeTransform<Derived>::TransformDependentNameType(
   } else if (isa<TypedefType>(Result)) {
     TLB.push<TypedefTypeLoc>(Result).set(TL.getElaboratedKeywordLoc(),
                                          QualifierLoc, TL.getNameLoc());
+  } else if (isa<UnresolvedUsingType>(Result)) {
+    auto NewTL = TLB.push<UnresolvedUsingTypeLoc>(Result);
+    NewTL.set(TL.getElaboratedKeywordLoc(), QualifierLoc, TL.getNameLoc());
   } else {
-    DependentNameTypeLoc NewTL = TLB.push<DependentNameTypeLoc>(Result);
+    auto NewTL = TLB.push<DependentNameTypeLoc>(Result);
     NewTL.setElaboratedKeywordLoc(TL.getElaboratedKeywordLoc());
     NewTL.setQualifierLoc(QualifierLoc);
     NewTL.setNameLoc(TL.getNameLoc());
diff --git a/clang/test/SemaCXX/using-decl-templates.cpp b/clang/test/SemaCXX/using-decl-templates.cpp
index c96c4879cb68c..58b30595b148c 100644
--- a/clang/test/SemaCXX/using-decl-templates.cpp
+++ b/clang/test/SemaCXX/using-decl-templates.cpp
@@ -153,3 +153,11 @@ T foo(T t) { // OK
 }
 } // namespace sss
 } // namespace func_templ
+
+namespace DependentName {
+  template <typename T> struct S {
+    using typename T::Ty;
+    static Ty Val;
+  };
+  template <typename T> typename S<T>::Ty S<T>::Val;
+} // DependentName