https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110513
Bug ID: 110513
Summary: Invalid use of incomplete type std::bool_constant
inside requires expression
Product: gcc
Version: 13.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
The following program
#include <type_traits>
struct B {
bool b = true;
};
// ok everywhere
static_assert( std::bool_constant<B{}.b>{}() );
// error in GCC
static_assert( requires() { std::bool_constant<B{}.b>{}(); } );
is accepted in Clang and MSVC, but GCC complains
<source>:11:56: error: invalid use of incomplete type
'std::bool_constant<B{}.b>'
11 | static_assert( requires() { std::bool_constant<B{}.b>{}(); } );
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
In file included from <source>:1:
/opt/compiler-explorer/gcc-13.1.0/include/c++/13.1.0/type_traits:62:12: note:
declaration of 'std::bool_constant<B{}.b>'
62 | struct integral_constant
| ^~~~~~~~~~~~~~~~~
Online demo: https://gcc.godbolt.org/z/csKanbM88
