gcc/testsuite/g++.dg/cpp2a/spaceship-synth8.C

// PR c++/94907
// { dg-do compile { target c++20 } }

namespace std { struct strong_ordering {
  int _v;
  constexpr strong_ordering (int v) :_v(v) {}
  constexpr operator int (void) const { return _v; }
  static const strong_ordering less;
  static const strong_ordering equal;
  static const strong_ordering greater;
};
constexpr strong_ordering strong_ordering::less = -1;
constexpr strong_ordering strong_ordering::equal = 0;
constexpr strong_ordering strong_ordering::greater = 1;
}

struct E;
struct D {
  virtual std::strong_ordering operator<=>(const struct E&) const = 0;
};
struct E : D {
  std::strong_ordering operator<=>(const E&) const override = default;
};