[Bug c++/80144] New: Concept introduced with "template<OtherConcept T>" is not diagnosed

[arthur.j.odwyer at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80144

            Bug ID: 80144
           Summary: Concept introduced with "template<OtherConcept T>" is
                    not diagnosed
           Product: gcc
           Version: c++-concepts
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: arthur.j.odwyer at gmail dot com
  Target Milestone: ---

Compile this code with GCC trunk and -fconcepts:

template<typename T>
concept bool Never = requires(T t) {
    { t != 42 };
};

template<typename T> concept bool First = Never<T>;
template<Never T> concept bool Second = true;

int main()
{
    static_assert(!Never<void*>);
    static_assert(!First<void*>);
    static_assert(!Second<void*>);  // static assertion failed
}

I claim that the final static_assert should not fail, or else GCC should
diagnose some kind of syntax error in my concept definitions (perhaps the
syntax "Never T" is not intended to be supported).