在gcc主干上使用-fconcepts对std:：list进行排序时出现预期的编译器错误？

首先，资料来源：

#include <list>
#include <algorithm>

using namespace std;

int main(int argc, const char* argv[]) {
    list<int> l = {3,-1,10};
    sort(begin(l), end(l));
    return 0;
}

然而，我看到的是：

In file included from /usr/local/include/c++/7.0.1/algorithm:62:0,
                 from concepts.cpp:2:
/usr/local/include/c++/7.0.1/bits/stl_algo.h: In instantiation of ‘void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = std::_List_iterator<int>; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’:
/usr/local/include/c++/7.0.1/bits/stl_algo.h:4822:18:   required from ‘void std::sort(_RAIter, _RAIter) [with _RAIter = std::_List_iterator<int>]’
concepts.cpp:8:26:   required from here
/usr/local/include/c++/7.0.1/bits/stl_algo.h:1969:22: error: no match for ‘operator-’ (operand types are ‘std::_List_iterator<int>’ and ‘std::_List_iterator<int>’)
     std::__lg(__last - __first) * 2,
               ~~~~~~~^~~~~~~~~
In file included from /usr/local/include/c++/7.0.1/bits/stl_algobase.h:67:0,
                 from /usr/local/include/c++/7.0.1/list:60,
                 from concepts.cpp:1:
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:389:5: note: candidate: template<class _IteratorL, class _IteratorR> decltype ((__y.base() - __x.base())) std::operator-(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)
     operator-(const reverse_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:389:5: note:   template argument deduction/substitution failed:
In file included from /usr/local/include/c++/7.0.1/algorithm:62:0,
                 from concepts.cpp:2:
/usr/local/include/c++/7.0.1/bits/stl_algo.h:1969:22: note:   ‘std::_List_iterator<int>’ is not derived from ‘const std::reverse_iterator<_Iterator>’
     std::__lg(__last - __first) * 2,
               ~~~~~~~^~~~~~~~~
In file included from /usr/local/include/c++/7.0.1/bits/stl_algobase.h:67:0,
                 from /usr/local/include/c++/7.0.1/list:60,
                 from concepts.cpp:1:
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:1191:5: note: candidate: template<class _IteratorL, class _IteratorR> decltype ((__x.base() - __y.base())) std::operator-(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&)
     operator-(const move_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:1191:5: note:   template argument deduction/substitution failed:
In file included from /usr/local/include/c++/7.0.1/algorithm:62:0,
                 from concepts.cpp:2:
/usr/local/include/c++/7.0.1/bits/stl_algo.h:1969:22: note:   ‘std::_List_iterator<int>’ is not derived from ‘const std::move_iterator<_IteratorL>’
     std::__lg(__last - __first) * 2,
               ~

在/usr/local/include/c++/7.0.1/算法：62:0中包含的文件中，
来自概念。cpp:2：
/usr/local/include/c++/7.0.1/bits/stl_algo.h:“void std:：_排序（_RandomAccessIterator，_RandomAccessIterator，_Compare）[with _RandomAccessIterator=std:_List_iterator；_Compare=_gnucxx:_ops:：_Iter_less_Iter]：
/usr/local/include/c++/7.0.1/bits/stl_-algo.h:4822:18:来自“void-std:：sort（_-RAIter，_-RAIter）[带_-RAIter=std:：_-List\u迭代器]”的必填项
概念。cpp:8:26：此处为必填项
/usr/local/include/c++/7.0.1/bits/stl_-algo.h:1969:22:错误：与“运算符-”不匹配（操作数类型为“std:：_-List_-iterator”和“std:_-List_-iterator”）
标准：：uuu lg（uuu last-uuu first）*2，
~~~~~~~^~~~~~~~~
在/usr/local/include/c++/7.0.1/bits/stl_algobase.h:67:0中包含的文件中，
从/usr/local/include/c++/7.0.1/list:60，
来自概念。cpp:1：
/usr/local/include/c++/7.0.1/bits/stl_迭代器.h:389:5：注：候选：模板decltype（（uu y.base（）-u x.base（）））std:：operator-（const std:：reverse_迭代器&，const std:：reverse_迭代器&）
运算符-（常量反向迭代器和，
^~~~~~~~
/usr/local/include/c++/7.0.1/bits/stl_迭代器。h:389:5:注意：模板参数推导/替换失败：
在/usr/local/include/c++/7.0.1/算法：62:0中包含的文件中，
来自概念。cpp:2：
/usr/local/include/c++/7.0.1/bits/stl_algo.h:1969:22：注意：“std:：_List_iterator”不是从“const std:：reverse_iterator”派生而来的
标准：：uuu lg（uuu last-uuu first）*2，
~~~~~~~^~~~~~~~~
在/usr/local/include/c++/7.0.1/bits/stl_algobase.h:67:0中包含的文件中，
从/usr/local/include/c++/7.0.1/list:60，
来自概念。cpp:1：
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:1191:5：注：候选：模板decltype（（uuu x.base（）-u y.base（）））std:：operator-（const std:：move_iterator&，const std:：move_iterator&）
运算符-（常量移动\u迭代器&\u x，
^~~~~~~~
/usr/local/include/c++/7.0.1/bits/stl_迭代器。h:1191:5:注意：模板参数推导/替换失败：
在/usr/local/include/c++/7.0.1/算法：62:0中包含的文件中，
来自概念。cpp:2：
/usr/local/include/c++/7.0.1/bits/stl_algo.h:1969:22：注意：“std:：_List_iterator”不是从“const std:：move_iterator”派生的
标准：：uuu lg（uuu last-uuu first）*2，
~

---

…这是我所期望的没有概念的输出。

我知道现在已经很晚了，您可能已经找到了答案，但对于其他人来说，用户出现错误的原因是因为他使用排序函数对负值进行排序。stl排序只接受正值。

我认为这个概念不适用图书馆。也许一旦TS完成并实施，你会看到一些不同的东西。你会认为是一个令人满意的答案吗？

$ /usr/local/bin/g++ --version
g++ (GCC) 7.0.1 20170401 (experimental)
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ /usr/local/bin/g++ -fconcepts concepts.cpp -o concepts

In file included from /usr/local/include/c++/7.0.1/algorithm:62:0,
                 from concepts.cpp:2:
/usr/local/include/c++/7.0.1/bits/stl_algo.h: In instantiation of ‘void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = std::_List_iterator<int>; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’:
/usr/local/include/c++/7.0.1/bits/stl_algo.h:4822:18:   required from ‘void std::sort(_RAIter, _RAIter) [with _RAIter = std::_List_iterator<int>]’
concepts.cpp:8:26:   required from here
/usr/local/include/c++/7.0.1/bits/stl_algo.h:1969:22: error: no match for ‘operator-’ (operand types are ‘std::_List_iterator<int>’ and ‘std::_List_iterator<int>’)
     std::__lg(__last - __first) * 2,
               ~~~~~~~^~~~~~~~~
In file included from /usr/local/include/c++/7.0.1/bits/stl_algobase.h:67:0,
                 from /usr/local/include/c++/7.0.1/list:60,
                 from concepts.cpp:1:
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:389:5: note: candidate: template<class _IteratorL, class _IteratorR> decltype ((__y.base() - __x.base())) std::operator-(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)
     operator-(const reverse_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:389:5: note:   template argument deduction/substitution failed:
In file included from /usr/local/include/c++/7.0.1/algorithm:62:0,
                 from concepts.cpp:2:
/usr/local/include/c++/7.0.1/bits/stl_algo.h:1969:22: note:   ‘std::_List_iterator<int>’ is not derived from ‘const std::reverse_iterator<_Iterator>’
     std::__lg(__last - __first) * 2,
               ~~~~~~~^~~~~~~~~
In file included from /usr/local/include/c++/7.0.1/bits/stl_algobase.h:67:0,
                 from /usr/local/include/c++/7.0.1/list:60,
                 from concepts.cpp:1:
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:1191:5: note: candidate: template<class _IteratorL, class _IteratorR> decltype ((__x.base() - __y.base())) std::operator-(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&)
     operator-(const move_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/local/include/c++/7.0.1/bits/stl_iterator.h:1191:5: note:   template argument deduction/substitution failed:
In file included from /usr/local/include/c++/7.0.1/algorithm:62:0,
                 from concepts.cpp:2:
/usr/local/include/c++/7.0.1/bits/stl_algo.h:1969:22: note:   ‘std::_List_iterator<int>’ is not derived from ‘const std::move_iterator<_IteratorL>’
     std::__lg(__last - __first) * 2,
               ~