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 #include "base/template_util.h" 13 14 // It is dangerous to post a task with a T* argument where T is a subtype of 15 // RefCounted(Base|ThreadSafeBase), since by the time the parameter is used, the 16 // object may already have been deleted since it was not held with a 17 // scoped_refptr. Example: http://crbug.com/27191 18 // The following set of traits are designed to generate a compile error 19 // whenever this antipattern is attempted. 20 21 namespace base::internal { 22 23 template <typename T> requires(T & x)24concept IsRefCountedType = requires(T& x) { 25 // There are no additional constraints on `AddRef()` and `Release()` since 26 // `scoped_refptr`, for better or worse`, seamlessly interoperates with other 27 // non-base types that happen to implement the same signatures (e.g. COM's 28 // IUnknown). 29 x.AddRef(); 30 x.Release(); 31 }; 32 33 // Human readable translation: you needed to be a scoped_refptr if you are a raw 34 // pointer type and are convertible to a RefCounted(Base|ThreadSafeBase) type. 35 template <typename T> 36 struct NeedsScopedRefptrButGetsRawPtr { 37 static_assert(!std::is_reference_v<T>, 38 "NeedsScopedRefptrButGetsRawPtr requires non-reference type."); 39 40 // TODO(danakj): Should ban native references and 41 // std::reference_wrapper here too. 42 static constexpr bool value = 43 (base::IsRawRef<T>::value && IsRefCountedType<base::RemoveRawRefT<T>>) || 44 (base::IsPointer<T>::value && IsRefCountedType<base::RemovePointerT<T>>); 45 }; 46 47 } // namespace base::internal 48 49 #endif // BASE_MEMORY_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_ 50