gcc/testsuite/g++.dg/cpp2a/concepts-pr67969.C

// { dg-do compile { target c++20 } }
// { dg-additional-options "-fconcepts-ts" }
template <class, class>
class NumericArray {};

template <class>
constexpr bool match_numeric_array = false;
template <class Scalar, class Shape>
constexpr bool
    match_numeric_array<NumericArray<Scalar, Shape>> =
        true;
template <class T>
concept bool cpt_NumericArrayContainer() {
  return match_numeric_array<T>;
}

template <class X>
concept bool cpt_NumericArray() {
  return requires{requires cpt_NumericArrayContainer<X>();};
}


template <class X>
requires !cpt_NumericArray<X>() auto func(int, X) {}

template <class X>
requires cpt_NumericArray<X>() auto func(int, X) {}

int main() {
  NumericArray<double, int> v5;
  func(0, v5);
}