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// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_
#define BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_
#include <type_traits>
#include "base/memory/raw_ptr.h"
#include "base/memory/raw_ref.h"
#include "base/template_util.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: http://crbug.com/27191
// 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, typename = void>
struct IsRefCountedType : std::false_type {};
template <typename T>
struct IsRefCountedType<T,
std::void_t<decltype(std::declval<T*>()->AddRef()),
decltype(std::declval<T*>()->Release())>>
: std::true_type {};
// 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.
template <typename T>
struct NeedsScopedRefptrButGetsRawPtr
: std::disjunction<
// TODO(danakj): Should ban native references and
// std::reference_wrapper here too.
std::conjunction<base::IsRawRef<T>,
IsRefCountedType<base::RemoveRawRefT<T>>>,
std::conjunction<base::IsPointer<T>,
IsRefCountedType<base::RemovePointerT<T>>>> {
static_assert(!std::is_reference_v<T>,
"NeedsScopedRefptrButGetsRawPtr requires non-reference type.");
};
} // namespace internal
} // namespace base
#endif // BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_
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