[clang] [Sema] Fix assertion in TreeTransform when rebuilding CXXParenListInitExpr (PR #203715)

[via cfe-commits]

https://github.com/arrowten updated https://github.com/llvm/llvm-project/pull/203715

>From 7efc304b4ebd52249ba3847ea77b27db6c6bc86b Mon Sep 17 00:00:00 2001
From: Ajay Wakodikar <ajaywakodikarsocial at gmail.com>
Date: Sat, 13 Jun 2026 12:49:23 -0400
Subject: [PATCH] [Sema] Fix assertion in TreeTransform when rebuilding
 CXXParenListInitExpr

---
 clang/include/clang/AST/ExprCXX.h                |  4 ++++
 clang/lib/Sema/TreeTransform.h                   |  3 ++-
 .../instantiate-member-initializers.cpp          | 16 ++++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index 36e5f8940228e..28ab1b7aa6d52 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -5184,6 +5184,10 @@ class CXXParenListInitExpr final
 
   ArrayRef<Expr *> getInitExprs() const { return getTrailingObjects(NumExprs); }
 
+  MutableArrayRef<Expr *> getUserSpecifiedInitExprs() {
+    return getTrailingObjects(NumUserSpecifiedExprs);
+  }
+
   ArrayRef<Expr *> getUserSpecifiedInitExprs() const {
     return getTrailingObjects(NumUserSpecifiedExprs);
   }
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 53107c827006d..8b61074d9db85 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -3412,7 +3412,8 @@ class TreeTransform {
 
     if (auto *PLE = dyn_cast<CXXParenListInitExpr>(Sub))
       return getSema().BuildCXXTypeConstructExpr(
-          TInfo, LParenLoc, PLE->getInitExprs(), RParenLoc, ListInitialization);
+          TInfo, LParenLoc, PLE->getUserSpecifiedInitExprs(), RParenLoc,
+          ListInitialization);
 
     return getSema().BuildCXXTypeConstructExpr(TInfo, LParenLoc,
                                                MultiExprArg(&Sub, 1), RParenLoc,
diff --git a/clang/test/SemaTemplate/instantiate-member-initializers.cpp b/clang/test/SemaTemplate/instantiate-member-initializers.cpp
index 63862063acdfe..813b0a375955a 100644
--- a/clang/test/SemaTemplate/instantiate-member-initializers.cpp
+++ b/clang/test/SemaTemplate/instantiate-member-initializers.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -Wall -verify %s
+// RUN: %clang_cc1 -fsyntax-only -Wall -verify -std=c++23 %s
 
 template<typename T> struct A {
   A() : a(1) { } // expected-error{{cannot initialize a member subobject of type 'void *' with an rvalue of type 'int'}}
@@ -41,3 +42,18 @@ template<typename T> struct Array {
   Array() : a() {}
 };
 Array<int> s;
+
+namespace GH194986 {
+#if __cplusplus >= 202302L
+  struct S {}; // expected-note 2{{candidate constructor}}
+  template <typename T> struct SS { T t1; T t2; };
+  template <class T, class... Args> T C(Args... args) { return SS("foo"); } // expected-error {{no viable conversion}}
+  S s = C<S>(); // expected-note {{in instantiation of function template specialization 'GH194986::C<GH194986::S>'}}
+
+  template <class T> struct SS2 { T t1, t2; };
+  template <class> void C2() {
+    SS2("foo"); // expected-warning 2{{expression result unused}}
+  }
+  template void C2<int>(); // expected-note {{in instantiation of function template specialization 'GH194986::C2<int>'}}
+#endif
+};