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

   1 // { dg-do compile { target c++11 } }
   2 // 2009-11-12  Paolo Carlini  <paolo.carlini@oracle.com>
   3 //
   4 // Copyright (C) 2009-2021 Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11 //
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING3.  If not see
  19 // <http://www.gnu.org/licenses/>.
  20
  21 #include <utility>
  22
  23 template<typename From, typename To>
  24   struct is_convertible_mini
  25   {
  26   private:
  27     typedef char one;
  28     typedef struct { char arr[2]; } two;
  29
  30     static one test(To);
  31     static two test(...);
  32
  33   public:
  34     static const bool value = sizeof(test(std::declval<From>())) == 1;
  35 };
  36
  37 template<typename From, typename To>
  38   const bool is_convertible_mini<From, To>::value;
  39
  40 void test01()
  41 {
  42   static_assert(is_convertible_mini<int*, const int*>::value, "#1");
  43   static_assert(!is_convertible_mini<const void*, void*>::value, "#2");
  44   static_assert(is_convertible_mini<float, double>::value, "#3");
  45   static_assert(!is_convertible_mini<bool, int*>::value, "#4");
  46   static_assert(is_convertible_mini<int(&)(int), int(*)(int)>::value, "#5");
  47   static_assert(!is_convertible_mini<void*, int*>::value, "#6");
  48 }