[CodeGen] Indirect fields can initialize a union

The first named data member is the field used to default initialize the
union.  An IndirectFieldDecl can introduce the first named data member
of a union.

llvm-svn: 238649

1 files changed, 7 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp b/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
index 72ecd65c28a..c89d5cc3892 100644
--- a/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
+++ b/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -314,9 +314,13 @@ void CGRecordLowering::lowerUnion() {
     // If this is the case, then we aught not to try and come up with a "better"
     // type, it might not be very easy to come up with a Constant which
     // correctly initializes it.
-    if (!SeenNamedMember && Field->getDeclName()) {
-      SeenNamedMember = true;
-      if (!isZeroInitializable(Field)) {
+    if (!SeenNamedMember) {
+      SeenNamedMember = Field->getIdentifier();
+      if (!SeenNamedMember)
+        if (const auto *FieldRD =
+                dyn_cast_or_null<RecordDecl>(Field->getType()->getAsTagDecl()))
+        SeenNamedMember = FieldRD->findFirstNamedDataMember();
+      if (SeenNamedMember && !isZeroInitializable(Field)) {
         IsZeroInitializable = IsZeroInitializableAsBase = false;
         StorageType = FieldType;
       }