https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111004
Bug ID: 111004
Summary: Visitor and concept error message
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: deco33000 at yandex dot com
Target Milestone: ---
The error code for the following situation is not clear.
The error is that struct A and B don't have a "bool activated;" member.
The issue is the variant does not reflect what the error is in an helpful way.
To ease your life, here is the godbolt:
https://godbolt.org/z/Wdr4zn5E1
Do you think it is possible to improve the diagnostic?
---------------------------
Reduced test case:
#include <iostream>
#include <variant>
#include <vector>
using namespace std;
template <class T>
concept My_concept = requires(T a) {
{ a.activated } -> std::same_as<bool &>;
};
struct A {
bool not_activated;
};
struct B {
bool not_activated;
int other;
};
auto test(variant<A, B> &v) -> void {
std::visit([](My_concept auto &&arg) { std::cout << "OK\n"; }, v);
}
int main() {
variant<A, B> v;
v = A();
test(v);
return 0;
}
------------------------
Thanks
