view libstdc++-v3/testsuite/18_support/comparisons/object/builtin-ptr-three-way.cc @ 19:2b5abeee2509 default tip

update gcc11
author anatofuz
date Mon, 25 May 2020 07:50:57 +0900
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// Copyright (C) 2020 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

// { dg-options "-std=gnu++2a" }
// { dg-do compile { target c++2a } }

#include <compare>

void
test01()
{
  struct X
  {
    operator int() const { return 0; }
    operator long*() const { return nullptr; }
  } x;

  // Not three-way-comparable because of ambiguous conversion to int or long*:
  static_assert( ! std::three_way_comparable<X> );

  // And therefore X is not three-way-comparable-with anything else
  // (because std::three_way_comparable_with<X, Y> requires that both
  // three_way_comparable<X> and three_way_comparable<Y> are true).
  static_assert( ! std::three_way_comparable_with<X, long*> );

  long l;
  // But <=> is valid and resolves to a builtin operator comparing pointers:
  auto c = &l <=> x;
  // So std::compare_three_way should be usable:
  auto c2 = std::compare_three_way()(&l, x);
}