libstdc++-v3/testsuite/20_util/unique_ptr/io/lwg2948.cc

   1 // Copyright (C) 2020-2021 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 run { target c++2a } }
  20
  21 #include <memory>
  22 #include <sstream>
  23 #include <testsuite_hooks.h>
  24
  25 template<typename S, typename T>
  26   concept streamable = requires (S& o, const T& p) { o << p; };
  27
  28 template<typename T, typename D>
  29   bool
  30   check(const std::unique_ptr<T, D>& p)
  31   {
  32     std::ostringstream ss1, ss2;
  33     ss1 << p;
  34     ss2 << p.get();
  35     return ss1.str() == ss2.str();
  36   }
  37
  38 void
  39 test01()
  40 {
  41   static_assert( streamable<std::ostream, std::unique_ptr<int>> );
  42
  43   std::unique_ptr<int> p;
  44   VERIFY( check(p) );
  45   p = std::make_unique<int>();
  46   VERIFY( check(p) );
  47 }
  48
  49 template<typename>
  50   struct deleter
  51   {
  52     struct pointer
  53     {
  54       pointer() { }
  55       pointer(std::nullptr_t) { }
  56       explicit operator bool() const { return false; }
  57       bool operator==(pointer) const { return true; }
  58     };
  59
  60     void operator()(pointer) const { }
  61   };
  62
  63 template<typename C, typename Traits>
  64   int
  65   operator<<(std::basic_ostream<C, Traits>& o, typename deleter<C>::pointer&&)
  66   {
  67     o << C{'P'};
  68     return 1; // no requirement that this operator returns the stream
  69   }
  70
  71 template<typename D>
  72   using Unique_ptr = std::unique_ptr<typename D::pointer, D>;
  73
  74 static_assert( streamable<std::ostream, Unique_ptr<deleter<char>>> );
  75 static_assert( ! streamable<std::ostream, Unique_ptr<deleter<wchar_t>>> );
  76 static_assert( ! streamable<std::wostream, Unique_ptr<deleter<char>>> );
  77 static_assert( streamable<std::wostream, Unique_ptr<deleter<wchar_t>>> );
  78
  79 void
  80 test02()
  81 {
  82   Unique_ptr<deleter<char>> p;
  83   VERIFY( check(p) );
  84 }
  85
  86 int
  87 main()
  88 {
  89   test01();
  90   test02();
  91 }