1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_ 6 #define BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_ 7 8 #include <type_traits> 9 10 #include "base/template_util.h" 11 12 // It is dangerous to post a task with a T* argument where T is a subtype of 13 // RefCounted(Base|ThreadSafeBase), since by the time the parameter is used, the 14 // object may already have been deleted since it was not held with a 15 // scoped_refptr. Example: http://crbug.com/27191 16 // The following set of traits are designed to generate a compile error 17 // whenever this antipattern is attempted. 18 19 namespace base { 20 21 // This is a base internal implementation file used by task.h and callback.h. 22 // Not for public consumption, so we wrap it in namespace internal. 23 namespace internal { 24 25 template <typename T, typename = void> 26 struct IsRefCountedType : std::false_type {}; 27 28 template <typename T> 29 struct IsRefCountedType<T, 30 void_t<decltype(std::declval<T*>()->AddRef()), 31 decltype(std::declval<T*>()->Release())>> 32 : std::true_type {}; 33 34 // Human readable translation: you needed to be a scoped_refptr if you are a raw 35 // pointer type and are convertible to a RefCounted(Base|ThreadSafeBase) type. 36 template <typename T> 37 struct NeedsScopedRefptrButGetsRawPtr 38 : conjunction<std::is_pointer<T>, 39 IsRefCountedType<std::remove_pointer_t<T>>> { 40 static_assert(!std::is_reference<T>::value, 41 "NeedsScopedRefptrButGetsRawPtr requires non-reference type."); 42 }; 43 44 } // namespace internal 45 46 } // namespace base 47 48 #endif // BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_ 49