这是一个SSCCE:
#include <memory>
#include <vector>
template <class T> struct my_allocator : std::allocator<T> {
//This overriding struct causes the error
template <class U> struct rebind {
typedef my_allocator<T> other;
};
//Ignore all this.
typedef std::allocator<T> base;
typename base::pointer allocate(typename base::size_type n, std::allocator<void>::const_pointer /*hint*/=nullptr) { return (T*)malloc(sizeof(T)*n); }
void deallocate(typename base::pointer p, typename base::size_type /*n*/) { free(p); }
};
int main(int /*argc*/, char* /*argv*/[]) {
std::vector<int,my_allocator<int>> vec;
return 0;
}
海湾合作委员会喜欢它。
ICC喜欢它。
铿锵喜欢。
甚至 MSVC 2013 也喜欢它。
但是 MSVC 2015 RC 吐出:
1>------ Build started: Project: Test Alloc, Configuration: Debug Win32 ------
1> main.cpp
1>c:\program files (x86)\microsoft visual studio 14.0\vc\include\vector(579): error C2664: 'void std::_Wrap_alloc<my_allocator<int>>::deallocate(int *,unsigned int)': cannot convert argument 1 from 'std::_Container_proxy *' to 'int *'
1> c:\program files (x86)\microsoft visual studio 14.0\vc\include\vector(579): note: Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
1> c:\program files (x86)\microsoft visual studio 14.0\vc\include\vector(574): note: while compiling class template member function 'void std::_Vector_alloc<std::_Vec_base_types<_Ty,_Alloc>>::_Free_proxy(void)'
1> with
1> [
1> _Ty=int,
1> _Alloc=my_allocator<int>
1> ]
1> c:\program files (x86)\microsoft visual studio 14.0\vc\include\vector(541): note: see reference to function template instantiation 'void std::_Vector_alloc<std::_Vec_base_types<_Ty,_Alloc>>::_Free_proxy(void)' being compiled
1> with
1> [
1> _Ty=int,
1> _Alloc=my_allocator<int>
1> ]
1> c:\program files (x86)\microsoft visual studio 14.0\vc\include\vector(668): note: see reference to class template instantiation 'std::_Vector_alloc<std::_Vec_base_types<_Ty,_Alloc>>' being compiled
1> with
1> [
1> _Ty=int,
1> _Alloc=my_allocator<int>
1> ]
1> c:\users\ian mallett\desktop\test-alloc\main.cpp(18): note: see reference to class template instantiation 'std::vector<int,my_allocator<int>>' being compiled
相关程序给出了类似的可疑错误。这里有两个:
错误 C2664: 'void std::_Wrap_alloc>::deallocate(int *,unsigned int)': cannot convert argument 1 from 'std::_Container_proxy *' to 'int *'
cannot convert argument 1 from 'std ::_Wrap_alloc>' 到 'const aligned_allocator &'
布尔问题:这是一个错误吗?如果是,我会(尝试)提交。
[编辑:如评论中所述,这只发生在调试模式下。在发布模式下,它编译并执行得很好。] [编辑:更简单的例子]