libstdc++-v3/testsuite/20_util/declval/requirements/1.cc

   1 // { dg-options "-std=gnu++11" }
   2 // { dg-do compile }
   3 // 2009-11-12  Paolo Carlini  <paolo.carlini@oracle.com>
   4 //
   5 // Copyright (C) 2009-2015 Free Software Foundation, Inc.
   6 //
   7 // This file is part of the GNU ISO C++ Library.  This library is free
   8 // software; you can redistribute it and/or modify it under the
   9 // terms of the GNU General Public License as published by the
  10 // Free Software Foundation; either version 3, or (at your option)
  11 // any later version.
  12 //
  13 // This library is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17 //
  18 // You should have received a copy of the GNU General Public License along
  19 // with this library; see the file COPYING3.  If not see
  20 // <http://www.gnu.org/licenses/>.
  21
  22 #include <utility>
  23
  24 template<typename From, typename To>
  25   struct is_convertible_mini
  26   {
  27   private:
  28     typedef char one;
  29     typedef struct { char arr[2]; } two;
  30
  31     static one test(To);
  32     static two test(...);
  33
  34   public:
  35     static const bool value = sizeof(test(std::declval<From>())) == 1;
  36 };
  37
  38 template<typename From, typename To>
  39   const bool is_convertible_mini<From, To>::value;
  40
  41 void test01()
  42 {
  43   static_assert(is_convertible_mini<int*, const int*>::value, "#1");
  44   static_assert(!is_convertible_mini<const void*, void*>::value, "#2");
  45   static_assert(is_convertible_mini<float, double>::value, "#3");
  46   static_assert(!is_convertible_mini<bool, int*>::value, "#4");
  47   static_assert(is_convertible_mini<int(&)(int), int(*)(int)>::value, "#5");
  48   static_assert(!is_convertible_mini<void*, int*>::value, "#6");
  49 }