blob: 5dbc183acdf3f71ba8dc62ab36462e11f70c332a [file] [log] [blame]
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <tuple>
#include <type_traits>
#include "base/memory/ref_counted.h"
// It is dangerous to post a task with a T* argument where T is a subtype of
// RefCounted(Base|ThreadSafeBase), since by the time the parameter is used, the
// object may already have been deleted since it was not held with a
// scoped_refptr. Example:
// The following set of traits are designed to generate a compile error
// whenever this antipattern is attempted.
namespace base {
// This is a base internal implementation file used by task.h and callback.h.
// Not for public consumption, so we wrap it in namespace internal.
namespace internal {
template <typename T>
struct NeedsScopedRefptrButGetsRawPtr {
enum {
// Human readable translation: you needed to be a scoped_refptr if you are a
// raw pointer type and are convertible to a RefCounted(Base|ThreadSafeBase)
// type.
value = (std::is_pointer<T>::value &&
(std::is_convertible<T, subtle::RefCountedBase*>::value ||
std::is_convertible<T, subtle::RefCountedThreadSafeBase*>::value))
template <typename Params>
struct ParamsUseScopedRefptrCorrectly {
enum { value = 0 };
template <>
struct ParamsUseScopedRefptrCorrectly<std::tuple<>> {
enum { value = 1 };
template <typename Head, typename... Tail>
struct ParamsUseScopedRefptrCorrectly<std::tuple<Head, Tail...>> {
enum { value = !NeedsScopedRefptrButGetsRawPtr<Head>::value &&
ParamsUseScopedRefptrCorrectly<std::tuple<Tail...>>::value };
} // namespace internal
} // namespace base