https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95132
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |ppalka at gcc dot
gnu.org
Target Milestone|--- |10.3
--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to Patrick Palka from comment #2)
> (In reply to Francesco Biscani from comment #0)
> > This is problematic because it means that another concept that would check
> > whether or not bar() can be called with a specific argument type would fail
> > with a hard compile time error, instead of marking the concept as not
> > satisfied.
>
> Would you have a concrete testcase for this behavior?
Ah, here's one:
$ cat testcase.C
template<typename T> struct A {
static auto f() requires false { return T::fail; }
};
template<typename T>
constexpr int v = requires { A<T>::f(); };
static_assert(!v<int>);
$ g++ -std=c++20 testcase.C
testcase.C: In instantiation of ‘static auto A<T>::f() requires false [with T
= int]’:
testcase.C: required from ‘constexpr const int v<int>’
testcase.C: required from here
testcase.C: error: ‘fail’ is not a member of ‘int’
2 | static auto f() requires false { return T::fail; }
| ^~~~
We wrongly issue a hard error for the reason you pointed out.
