libstdc++-v3/testsuite/20_util/forward/f_neg.cc

   1 // { dg-do compile { target c++11 } }
   2
   3 // Copyright (C) 2010-2021 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10 //
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15 //
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING3.  If not see
  18 // <http://www.gnu.org/licenses/>.
  19
  20 // { dg-error "static assertion failed" "" { target *-*-* } 89 }
  21
  22 #include <utility>
  23
  24 template <class T>
  25   struct C
  26   {
  27     T t_;
  28
  29     C() {}
  30
  31     explicit C(const T& t) : t_(t) { }
  32
  33     template <class U,
  34               class = typename std::enable_if
  35                     <
  36                         std::is_convertible<U, T>::value
  37                     >::type>
  38       C(C<U>&& c) : t_(std::forward<T>(c.t_)) { }
  39   };
  40
  41 class B;
  42
  43 class A
  44 {
  45   int data_;
  46
  47   friend class B;
  48 public:
  49   explicit
  50   A(int data = 1)
  51   : data_(data) { }
  52
  53   ~A() { data_ = -1; }
  54
  55   void test() const
  56   {
  57     __builtin_abort();
  58   }
  59 };
  60
  61 class B
  62 {
  63   int data_;
  64 public:
  65   explicit
  66   B(int data = 1)
  67   : data_(data) { }
  68
  69   B(const A& a) : data_(a.data_) { }
  70
  71   B(A&& a) : data_(a.data_) { a.data_ = 100; }
  72
  73   ~B() { data_ = -1; }
  74
  75   void test() const
  76   {
  77     __builtin_abort();
  78   }
  79 };
  80
  81 // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2951.html
  82 // Test F.
  83 int main()
  84 {
  85   A a(3);
  86   C<A> ca(a);
  87   C<const B&> cb(std::move(ca));
  88   cb.t_.test();
  89 }