[Bug c++/67225] [concepts] Expression constraint with a constrained result turns off access checking

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67225

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Testcase from Bug 78715 comment 0:

template <class>
concept bool Dummy = true;

template <typename>
class example {
    template <Dummy<> U>
    friend auto func();
};

class test {
    test() = default;
};

int main()
{
    test t;
}


Testcase from Bug 78715 comment 1:

template <class, class>
concept bool C1 = true;

template <class>
concept bool C2 = requires { { 42 } -> C1<int>; };

int main() {
    class A { int x; } a;
    a.x = 42;
}


Testcase from Bug 78715 comment 2:

template<typename A, typename T>
concept bool SomeConcept = true;

template <typename T>
void breaker(SomeConcept<int>);

class SomeClass {
    int privateMember;
};

int main() {
    return SomeClass().privateMember;
}