From 01b47eb86c991f88d3117f494ebd1826fd3ab41e Mon Sep 17 00:00:00 2001
From: Timm Baeder <tbaeder@redhat.com>
Date: Wed, 23 Jul 2025 05:28:37 +0200
Subject: [clang][bytecode] Only implicitly start lifetime of
 trivially-default-constructible union members (#149835)

See
https://github.com/llvm/llvm-project/commit/faee39baa87e43f4b746dd77e479268391163658
---
 clang/lib/AST/ByteCode/Compiler.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'clang/lib/AST/ByteCode/Compiler.cpp')

diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index 07efd6f8..e760055 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -25,11 +25,18 @@ using APSInt = llvm::APSInt;
 namespace clang {
 namespace interp {
 
+static bool hasTrivialDefaultCtorParent(const FieldDecl *FD) {
+  assert(FD);
+  assert(FD->getParent()->isUnion());
+  const auto *CXXRD = dyn_cast<CXXRecordDecl>(FD->getParent());
+  return !CXXRD || CXXRD->hasTrivialDefaultConstructor();
+}
+
 static bool refersToUnion(const Expr *E) {
   for (;;) {
     if (const auto *ME = dyn_cast<MemberExpr>(E)) {
       if (const auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl());
-          FD && FD->getParent()->isUnion())
+          FD && FD->getParent()->isUnion() && hasTrivialDefaultCtorParent(FD))
         return true;
       E = ME->getBase();
       continue;
-- 
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