https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105050
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I think clang still gives a better error message here though:
<source>:43:15: error: static assertion expression is not an integral constant
expression
static_assert(test_swap());
^~~~~~~~~~~
<source>:18:17: note: non-constexpr function '_M_swap_val' cannot be used in a
constant expression
this->_M_swap_val(__x);
^
<source>:38:6: note: in call to '&e1->swap(e2)'
e1.swap(e2);
^
<source>:43:15: note: in call to 'test_swap()'
static_assert(test_swap());
^
<source>:4:10: note: declared here
void _M_swap_val(expected&) { }
^
