[clang][Interp] Prepare return value for composite InitListExprs

Author: tbaederr

clang/lib/AST/Interp/ByteCodeExprGen.cpp

@@ -1101,6 +1101,23 @@ bool ByteCodeExprGen<Emitter>::visitInitList(ArrayRef<const Expr *> Inits,
     return this->delegate(Inits[0]);
   }
 
+  // Prepare composite return value.
+  if (!Initializing) {
+    if (GlobalDecl) {
+      std::optional<unsigned> GlobalIndex = P.createGlobal(E);
+      if (!GlobalIndex)
+        return false;
+      if (!this->emitGetPtrGlobal(*GlobalIndex, E))
+        return false;
+    } else {
+      std::optional<unsigned> LocalIndex = allocateLocal(E);
+      if (!LocalIndex)
+        return false;
+      if (!this->emitGetPtrGlobal(*LocalIndex, E))
+        return false;
+    }
+  }
+
   QualType T = E->getType();
   if (T->isRecordType()) {
     const Record *R = getRecord(E->getType());

clang/test/AST/Interp/references.cpp

@@ -125,3 +125,8 @@ constexpr int RecordWithRef2() {
   return r.a;
 }
 static_assert(RecordWithRef2() == 200, "");
+
+const char (&nonextended_string_ref)[3] = {"hi"};
+static_assert(nonextended_string_ref[0] == 'h', "");
+static_assert(nonextended_string_ref[1] == 'i', "");
+static_assert(nonextended_string_ref[2] == '\0', "");