libstdc++-v3/testsuite/std/concepts/concepts.lang/concept.commonref/1.cc

   1 // Copyright (C) 2019-2021 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-options "-std=gnu++2a" }
  19 // { dg-do compile { target c++2a } }
  20
  21 #include <concepts>
  22
  23 static_assert( std::common_reference_with<int, int> );
  24 static_assert( std::common_reference_with<int, const int> );
  25 static_assert( std::common_reference_with<int&&, const int&> );
  26 static_assert( std::common_reference_with<int&, const int&&> );
  27 static_assert( ! std::common_reference_with<int, void> );
  28 static_assert( ! std::common_reference_with<int, int*> );
  29 static_assert( ! std::common_reference_with<int, int()> );
  30
  31 struct A { A(int) { } };
  32 static_assert( std::common_reference_with<A, int> );
  33
  34 struct B { };
  35 static_assert( ! std::common_reference_with<A, B> );
  36
  37 struct C { C(A&) { } };
  38 static_assert( std::common_reference_with<A&, C> );
  39 static_assert( std::common_reference_with<A&, C&&> );
  40 static_assert( std::common_reference_with<A&, const C&> );
  41 static_assert( std::common_reference_with<A&, C&> );
  42 static_assert( ! std::common_reference_with<const A&, C> );
  43 static_assert( ! std::common_reference_with<const A&, const C&> );
  44
  45 struct D;
  46 struct E { E(D&) { } };
  47 struct D { D(E&) { } };
  48 static_assert( ! std::common_reference_with<D&, E&> ); // ambiguous conversion
  49
  50 struct F;
  51 struct G { G(const F&) { } };
  52 struct F { F(const G&) { } };
  53 namespace std
  54 {
  55   template<template<typename> class Qual1, template<typename> class Qual2>
  56     struct basic_common_reference<F, G, Qual1, Qual2>
  57     { using type = Qual1<Qual2<F>>; };
  58   template<template<typename> class Qual1, template<typename> class Qual2>
  59     struct basic_common_reference<G, F, Qual1, Qual2>
  60     { using type = Qual1<Qual2<F>>; };
  61 }
  62
  63 static_assert( ! std::common_reference_with<F&, G&> );
  64 static_assert( std::common_reference_with<F, G> );
  65 static_assert( std::common_reference_with<F, const G> );
  66 static_assert( std::common_reference_with<const F, const G> );
  67
  68 struct Base { };
  69 struct Derived : Base { };
  70 static_assert( std::common_reference_with<Derived&, Base&> );
  71 static_assert( std::common_with<Derived*, Base*> );