From: "Daniel Krügler" <daniel.kruegler@gmail.com>
To: GCC <gcc@gcc.gnu.org>
Subject: Design question LWG 2861: basic_string should require that charT match traits::char_type
Date: Sun, 12 Mar 2017 13:21:00 -0000 [thread overview]
Message-ID: <CAGNvRgDeqGG=39HVhs6-7mzLPxdhHGgBxySnjWEwT6O-wKUXYQ@mail.gmail.com> (raw)
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
next reply other threads:[~2017-03-12 13:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-12 13:21 Daniel Krügler [this message]
2017-03-13 10:56 ` Jonathan Wakely
2017-03-13 11:33 ` Daniel Krügler
2017-03-13 17:31 ` Jonathan Wakely
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