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

   1 // { dg-options "-std=c++11" }
   2 // { dg-do compile }
   3
   4 // Copyright (C) 2012-2014 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 <type_traits>
  22 #include <chrono>
  23
  24 // Helper types:
  25 struct has_type_impl
  26 {
  27   template<typename T, typename = typename T::type>
  28   static std::true_type test(int);
  29   template<typename>
  30   static std::false_type test(...);
  31 };
  32
  33 template<typename T>
  34 struct has_type : public decltype(has_type_impl::test<T>(0))
  35 {};
  36
  37 template<typename T, typename Expected>
  38 struct is_expected_type : public std::is_same<typename T::type, Expected>
  39 {};
  40
  41 template<typename P1, typename P2>
  42 struct and_ : public std::conditional<P1::value, P2, std::false_type>::type
  43 {};
  44
  45 template<typename T, typename Expected>
  46 struct is_type : public and_<has_type<T>, is_expected_type<T, Expected>>
  47 {};
  48
  49 // Inspection types:
  50
  51 typedef std::chrono::duration<int, std::nano> din;
  52 typedef std::chrono::duration<double, std::nano> ddn;
  53 typedef std::chrono::duration<int, std::milli> dim;
  54
  55 static_assert(is_type<std::common_type<din, din>, din>(), "");
  56 static_assert(is_type<std::common_type<din, din, din>, din>(), "");
  57
  58 static_assert(is_type<std::common_type<din, ddn>, ddn>(), "");
  59 static_assert(is_type<std::common_type<din, din, ddn>, ddn>(), "");
  60 static_assert(is_type<std::common_type<din, ddn>, ddn>(), "");
  61 static_assert(is_type<std::common_type<ddn, din, din>, ddn>(), "");
  62
  63 static_assert(!has_type<std::common_type<din, int>>(), "");
  64 static_assert(!has_type<std::common_type<din, din, int>>(), "");
  65 static_assert(!has_type<std::common_type<int, din, din>>(), "");
  66