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 <tuple> 9 #include <type_traits> 10 11 #include "base/memory/ref_counted.h" 12 13 // It is dangerous to post a task with a T* argument where T is a subtype of 14 // RefCounted(Base|ThreadSafeBase), since by the time the parameter is used, the 15 // object may already have been deleted since it was not held with a 16 // scoped_refptr. Example: http://crbug.com/27191 17 // The following set of traits are designed to generate a compile error 18 // whenever this antipattern is attempted. 19 20 namespace base { 21 22 // This is a base internal implementation file used by task.h and callback.h. 23 // Not for public consumption, so we wrap it in namespace internal. 24 namespace internal { 25 26 template <typename T> 27 struct NeedsScopedRefptrButGetsRawPtr { 28 enum { 29 // Human readable translation: you needed to be a scoped_refptr if you are a 30 // raw pointer type and are convertible to a RefCounted(Base|ThreadSafeBase) 31 // type. 32 value = (std::is_pointer<T>::value && 33 (std::is_convertible<T, subtle::RefCountedBase*>::value || 34 std::is_convertible<T, subtle::RefCountedThreadSafeBase*>::value)) 35 }; 36 }; 37 38 template <typename Params> 39 struct ParamsUseScopedRefptrCorrectly { 40 enum { value = 0 }; 41 }; 42 43 template <> 44 struct ParamsUseScopedRefptrCorrectly<std::tuple<>> { 45 enum { value = 1 }; 46 }; 47 48 template <typename Head, typename... Tail> 49 struct ParamsUseScopedRefptrCorrectly<std::tuple<Head, Tail...>> { 50 enum { value = !NeedsScopedRefptrButGetsRawPtr<Head>::value && 51 ParamsUseScopedRefptrCorrectly<std::tuple<Tail...>>::value }; 52 }; 53 54 } // namespace internal 55 56 } // namespace base 57 58 #endif // BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_ 59
