libstdc++-v3/testsuite/20_util/duration/requirements/sfinae_friendly_1.cc

   1 // { dg-do compile { target c++11 } }
   2
   3 // Copyright (C) 2012-2018 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 #include <type_traits>
  21 #include <chrono>
  22
  23 // Helper types:
  24 struct has_type_impl
  25 {
  26   template<typename T, typename = typename T::type>
  27   static std::true_type test(int);
  28   template<typename>
  29   static std::false_type test(...);
  30 };
  31
  32 template<typename T>
  33 struct has_type : public decltype(has_type_impl::test<T>(0))
  34 {};
  35
  36 template<typename T, typename Expected>
  37 struct is_expected_type : public std::is_same<typename T::type, Expected>
  38 {};
  39
  40 template<typename P1, typename P2>
  41 struct and_ : public std::conditional<P1::value, P2, std::false_type>::type
  42 {};
  43
  44 template<typename T, typename Expected>
  45 struct is_type : public and_<has_type<T>, is_expected_type<T, Expected>>
  46 {};
  47
  48 // Inspection types:
  49
  50 typedef std::chrono::duration<int, std::nano> din;
  51 typedef std::chrono::duration<double, std::nano> ddn;
  52 typedef std::chrono::duration<int, std::milli> dim;
  53
  54 static_assert(is_type<std::common_type<din, din>, din>(), "");
  55 static_assert(is_type<std::common_type<din, din, din>, din>(), "");
  56
  57 static_assert(is_type<std::common_type<din, ddn>, ddn>(), "");
  58 static_assert(is_type<std::common_type<din, din, ddn>, ddn>(), "");
  59 static_assert(is_type<std::common_type<din, ddn>, ddn>(), "");
  60 static_assert(is_type<std::common_type<ddn, din, din>, ddn>(), "");
  61
  62 static_assert(!has_type<std::common_type<din, int>>(), "");
  63 static_assert(!has_type<std::common_type<din, din, int>>(), "");
  64 static_assert(!has_type<std::common_type<int, din, din>>(), "");
  65