llvm/clang/test/CXX/temp/temp.spec/temp.expl.spec/p14-23.cpp

// RUN: %clang_cc1 -std=c++20 -verify %s

namespace N0 {
  template<int I>
  concept C = I >= 4;

  template<int I>
  concept D = I < 8;

  template<int I>
  struct A { // #defined-here
    constexpr static int f() { return 0; }
    constexpr static int f() requires C<I> && D<I> { return 1; }
    constexpr static int f() requires C<I> { return 2; }

    constexpr static int g() requires C<I> { return 0; } // #candidate-0
    constexpr static int g() requires D<I> { return 1; } // #candidate-1

    constexpr static int h() requires C<I> { return 0; } // expected-note {{member declaration nearly matches}}
  };

  template<>
  constexpr int A<2>::f() { return 3; }

  template<>
  constexpr int A<4>::f() { return 4; }

  template<>
  constexpr int A<8>::f() { return 5; }

  static_assert(A<3>::f() == 0);
  static_assert(A<5>::f() == 1);
  static_assert(A<9>::f() == 2);
  static_assert(A<2>::f() == 3);
  static_assert(A<4>::f() == 4);
  static_assert(A<8>::f() == 5);

  template<>
  constexpr int A<0>::g() { return 2; }

  template<>
  constexpr int A<8>::g() { return 3; }

  template<>
  constexpr int A<6>::g() { return 4; } // expected-error {{ambiguous member function specialization 'N0::A<6>::g' of 'N0::A::g'}}
                                        // expected-note@#candidate-0 {{member function specialization matches 'g'}}
                                        // expected-note@#candidate-1 {{member function specialization matches 'g'}}

  static_assert(A<9>::g() == 0);
  static_assert(A<1>::g() == 1);
  static_assert(A<0>::g() == 2);
  static_assert(A<8>::g() == 3);

  template<>
  constexpr int A<4>::h() { return 1; }

  template<>
  constexpr int A<0>::h() { return 2; } // expected-error {{out-of-line definition of 'h' does not match any declaration in 'N0::A<0>'}}
                                        // expected-note@#defined-here {{defined here}}

  static_assert(A<5>::h() == 0);
  static_assert(A<4>::h() == 1);
} // namespace N0

namespace N1 {
  template<int I>
  concept C = I > 0;

  template<int I>
  concept D = I > 1;

  template<int I>
  concept E = I > 2;

  template<int I>
  struct A {
    void f() requires C<I> && D<I>; // expected-note {{member function specialization matches 'f'}}
    void f() requires C<I> && E<I>; // expected-note {{member function specialization matches 'f'}}
    void f() requires C<I> && D<I> && true; // expected-note {{member function specialization matches 'f'}}

    void g() requires C<I> && E<I>; // expected-note {{member function specialization matches 'g'}}
    void g() requires C<I> && D<I>; // expected-note {{member function specialization matches 'g'}}
    void g() requires C<I> && D<I> && true; // expected-note {{member function specialization matches 'g'}}
  };

  template<>
  void A<3>::f(); // expected-error {{ambiguous member function specialization 'N1::A<3>::f' of 'N1::A::f'}}

  template<>
  void A<3>::g(); // expected-error {{ambiguous member function specialization 'N1::A<3>::g' of 'N1::A::g'}}
} // namespace N1