https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111712
Bug ID: 111712
Summary: Syntax error when passing function parameter as NTTP
in requires-clause
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hewillk at gmail dot com
Target Milestone: ---
Regardless of whether the code is well-formed or not, this should be valid
syntax
https://godbolt.org/z/4qM9nG4WP
#include <type_traits>
template<bool B>
void f(std::bool_constant<B> b)
requires requires { typename std::bool_constant<b()>; };
int main() {
f(std::true_type{});
}
However, GCC givs
<source>:5:54: error: template argument 1 is invalid
<source>:5:37: error: invalid use of template-name 'std::bool_constant' without
an argument list
5 | requires requires { typename std::bool_constant<b()>; };
| ^~~~~~~~~~~~~
In file included from <source>:1:
/opt/compiler-explorer/gcc-trunk-20231005/include/c++/14.0.0/type_traits:120:11:
note: 'template<bool __v> using std::bool_constant = std::__bool_constant<__v>'
declared here
120 | using bool_constant = __bool_constant<__v>;
| ^~~~~~~~~~~~~
<source>:5:50: error: expected '(' before '<' token
5 | requires requires { typename std::bool_constant<b()>; };
| ^
| (
<source>:5:55: error: expected primary-expression before ';' token
5 | requires requires { typename std::bool_constant<b()>; };
| ^
