1 // Copyright 2011 The Chromium Authors 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/memory/raw_ptr.h" 11 #include "base/memory/raw_ref.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::internal { 21 22 template <typename T> requires(T & x)23concept IsRefCountedType = requires(T& x) { 24 // There are no additional constraints on `AddRef()` and `Release()` since 25 // `scoped_refptr`, for better or worse`, seamlessly interoperates with other 26 // non-base types that happen to implement the same signatures (e.g. COM's 27 // IUnknown). 28 x.AddRef(); 29 x.Release(); 30 }; 31 32 // Human readable translation: you needed to be a scoped_refptr if you are a raw 33 // pointer type and are convertible to a RefCounted(Base|ThreadSafeBase) type. 34 template <typename T> 35 struct NeedsScopedRefptrButGetsRawPtr { 36 static_assert(!std::is_reference_v<T>, 37 "NeedsScopedRefptrButGetsRawPtr requires non-reference type."); 38 39 // TODO(danakj): Should ban native references and 40 // std::reference_wrapper here too. 41 static constexpr bool value = 42 (base::IsRawRef<T>::value && IsRefCountedType<base::RemoveRawRefT<T>>) || 43 (base::IsRawPointer<T> && IsRefCountedType<base::RemoveRawPointerT<T>>); 44 }; 45 46 } // namespace base::internal 47 48 #endif // BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_ 49