https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67704
Bug ID: 67704
Summary: [concepts] requirements not being applied to aliases
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ryan.burn at gmail dot com
Target Milestone: ---
I think the below code should compile: the first version of "f" should trigger
SFINAE but the second version should match so that the program prints 2.
But it compiles with this error with gcc 6:
t3.cpp: In substitution of ‘template<class X> requires
predicate(requires{typename X::type;}) using Q = typename X::type [with X =
int]’:
t3.cpp:12:21: required from ‘struct A<int>’
t3.cpp:19:30: required by substitution of ‘template<class X> requires
predicate(requires{typename X::Q;}) using R = typename A::type [with X = int]’
t3.cpp:35:20: required from here
t3.cpp:8:27: error: ‘int’ is not a class, struct, or union type
using Q = typename X::type;
//////////////////////////////////////////////
#include <type_traits>
#include <iostream>
template<class X>
requires requires {
typename X::type;
}
using Q = typename X::type;
template <class X>
struct A {
using type = Q<X>*;
};
template<class X>
requires requires {
typename Q<X>;
}
using R = typename A<X>::type;
template <class X>
requires requires {
typename R<X>;
}
int f(X x) {
return 1;
}
template<class X>
int f(X x) {
return 2;
}
int main() {
std::cout << f(22) << '\n';
return 0;
}
//////////////////////////////////////////////