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

   1 // { dg-do compile { target c++11 } }
   2
   3 // Copyright (C) 2010-2018 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 *-*-* } 87 }
  21
  22 #include <list>
  23
  24 template <class T>
  25   struct C
  26   {
  27     T t_;
  28
  29     template <class U,
  30               class = typename std::enable_if
  31                     <
  32                         !std::is_lvalue_reference<U>::value
  33                     >::type>
  34       C(U&& u) : t_(std::forward<T>(std::move(u).get())) {}
  35   };
  36
  37 class A
  38 {
  39   int data_;
  40 public:
  41   explicit
  42   A(int data = 1)
  43   : data_(data) { }
  44
  45   ~A() { data_ = -1; }
  46
  47   void test() const
  48   {
  49     __builtin_abort();
  50   }
  51 };
  52
  53 class Awrap
  54 {
  55   const A& a_;
  56 public:
  57   explicit Awrap(const A& a) : a_(a) {}
  58   const A /* & */ get() const { return a_; }
  59 };
  60
  61 template <class C>
  62   void test(C c)
  63   {
  64     c.t_.test();
  65   }
  66
  67 // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2951.html
  68 // Test C.
  69 int main()
  70 {
  71   std::list<C<const A&> > list;
  72   A a(3);
  73   C<const A&> c((Awrap(a)));
  74   list.push_back(c);
  75   test(c);
  76   test(list.front());
  77 }