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[thirdparty/gcc.git] / libstdc++-v3 / testsuite / 24_iterators / indirect_callable / projected.cc

// Copyright (C) 2019-2020 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 <iterator>

template<typename T>
  using PI = std::projected<T, std::identity>;

static_assert(std::same_as<PI<int*>::value_type, int>);
static_assert(std::same_as<decltype(*std::declval<const PI<int*>&>()), int&>);

struct X
{
  using value_type = char*;
  char* const& operator*() &;
};
static_assert( std::readable<X> );
static_assert(std::same_as<PI<X>::value_type, char*>);
static_assert(std::same_as<decltype(*std::declval<PI<X>&>()), char* const&>);

struct Y;
using PY = std::projected<const Y*, int Y::*>;
static_assert(std::same_as<PY::value_type, int>);
static_assert(std::same_as<decltype(*std::declval<PY&>()), const int&>);