I'm now working on
http://cplusplus.github.io/LWG/lwg-defects.html#2861
The new wording state is now equivalent to basic_string_view, whose
current implementation doesn't bother verifying the requirement, so
this code (which as UB) currently compiles just fine:
#include <string>
#include <string_view>
struct MyTraits : std::char_traits<char>
{
typedef unsigned char char_type;
};
int main()
{
std::basic_string<char, MyTraits> my_string;
std::basic_string_view<char, MyTraits> my_string_view;
}
So the least I could do is just - nothing. But it seems to me that we
could protect users from doing such silly things by adding a
static_assert to both basic_string and basic_string_view, the former
being equivalent to
#if __cplusplus >= 201103L
static_assert(__are_same<value_type, _CharT>::value,
"traits_type::char_type must be equal to _CharT");
#endif
and the latter an unconditional
static_assert(is_same<typename _Traits::char_type, _CharT>::value,
"traits_type::char_type must be equal to _CharT");
Would you agree with that course of action?
Thanks,
- Daniel