1 files changed, 37 insertions, 0 deletions
diff --git a/ipc/glue/IPDLStructMember.h b/ipc/glue/IPDLStructMember.h
new file mode 100644
index 0000000000..d2e3636054
--- /dev/null
+++ b/ipc/glue/IPDLStructMember.h
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ipc_IPDLStructMember_h
+#define mozilla_ipc_IPDLStructMember_h
+
+#include <type_traits>
+#include <utility>
+#include "mozilla/Attributes.h"
+
+namespace mozilla::ipc {
+
+// For types which are trivially default constructible, like `int`, force the
+// value constructor by wrapping the type in this struct.  This is an
+// implementation detail which will be hidden by the generated IPDL compiler
+// code.
+template <typename T>
+struct IPDLStructMemberWrapper {
+  template <typename... Args>
+  MOZ_IMPLICIT IPDLStructMemberWrapper(Args&&... aArgs)
+      : mVal(std::forward<Args>(aArgs)...) {}
+  MOZ_IMPLICIT operator T&() { return mVal; }
+  MOZ_IMPLICIT operator const T&() const { return mVal; }
+  T mVal{};
+};
+
+template <typename T>
+using IPDLStructMember =
+    std::conditional_t<std::is_trivially_default_constructible_v<T>,
+                       IPDLStructMemberWrapper<T>, T>;
+
+}  // namespace mozilla::ipc
+
+#endif  // mozilla_ipc_IPDLStructMember_h