libstdc++-v3/testsuite/20_util/is_nothrow_invocable/value_ext.cc

   1 // Copyright (C) 2016-2022 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do compile { target c++11 } }
  19
  20 #include <type_traits>
  21
  22 template<typename... T>
  23   constexpr bool is_nt_invocable()
  24   { return std::__is_nothrow_invocable<T...>::value; }
  25
  26 template<typename R, typename... T>
  27   struct ConvIsNothrow
  28   {
  29     using result_type = typename std::__invoke_result<T...>::type;
  30     static void test(std::true_type, R) noexcept;
  31     static void test(std::false_type, const result_type&);
  32     static constexpr bool value
  33       = noexcept(test(std::is_convertible<result_type, R>(),
  34                       std::declval<result_type>()));
  35   };
  36
  37 template<typename... T>
  38   struct ConvIsNothrow<void, T...> : std::true_type
  39   { };
  40
  41 template<typename R, typename... T>
  42   constexpr bool is_nt_invocable_conv(std::true_type)
  43   {
  44     return ConvIsNothrow<R, T...>::value;
  45   }
  46
  47 template<typename R, typename... T>
  48   constexpr bool is_nt_invocable_conv(std::false_type) { return false; }
  49
  50 template<typename R, typename... T>
  51   constexpr bool is_nt_invocable_r()
  52   {
  53     return is_nt_invocable_conv<R, T...>(std::__is_nothrow_invocable<T...>{});
  54   }
  55
  56 #define IS_NT_INVOCABLE_DEFINED
  57 #include "value.cc"