https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121046
Bug ID: 121046
Summary: Asking is_constructible_v<std::bitset<1>, NonTrivial*>
is ill-formed
Product: gcc
Version: 15.1.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
Found by the libc++ testsuite:
#include <bitset>
struct NonTrivial { ~NonTrivial() { } };
static_assert( ! std::is_constructible_v<std::bitset<1>, NonTrivial*> );
This fails outside the immediate context, due to the bitset(const CharT*)
constructor instantiating std::basic_string<NonTrivial>:
In file included from /home/jwakely/gcc/16/include/c++/16.0.0/string:56,
from /home/jwakely/gcc/16/include/c++/16.0.0/bitset:54,
from bitset.cc:1:
/home/jwakely/gcc/16/include/c++/16.0.0/bits/basic_string.h: In instantiation
of 'class std::__cxx11::basic_string<NonTrivial, std::char_traits<NonTrivial>,
std::allocator<NonTrivial> >':
/home/jwakely/gcc/16/include/c++/16.0.0/bitset:1053:2: required by
substitution of 'template<class _CharT> std::bitset<1>::bitset(const _CharT*,
typename std::__bitset::__string<_CharT>::size_type, _CharT, _CharT) [with
_CharT = NonTrivial]'
1053 | bitset(const _CharT* __str,
| ^~~~~~
/home/jwakely/gcc/16/include/c++/16.0.0/type_traits:3621:46: required from
'constexpr const bool std::is_constructible_v<std::bitset<1>, NonTrivial*>'
3621 | inline constexpr bool is_constructible_v = __is_constructible(_Tp,
_Args...);
|
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bitset.cc:3:23: required from here
3 | static_assert( ! std::is_constructible_v<std::bitset<1>, NonTrivial*>
);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/jwakely/gcc/16/include/c++/16.0.0/bits/basic_string.h:97:21: error:
static assertion failed
97 | static_assert(is_trivially_copyable_v<_CharT>
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/jwakely/gcc/16/include/c++/16.0.0/bits/basic_string.h:97:21: note:
'std::is_trivially_copyable_v<NonTrivial>' evaluates to false
