libstdc++-v3/testsuite/20_util/to_underlying/1.cc

   1 // Copyright (C) 2021-2022 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-options "-std=gnu++23" }
  19 // { dg-do compile { target c++23 } }
  20
  21 #include <utility>
  22
  23 #ifndef __cpp_lib_to_underlying
  24 # error "Feature-test macro for to_underlying missing in <utility>"
  25 #elif __cpp_lib_to_underlying != 202102L
  26 # error "Feature-test macro for to_underlying has wrong value in <utility>"
  27 #endif
  28
  29 void
  30 test01()
  31 {
  32   enum E : short { e0, e1, e2 };
  33   E e = e0;
  34   static_assert( std::is_same_v<decltype(std::to_underlying(e)), short> );
  35   static_assert( noexcept(std::to_underlying(e)) );
  36   static_assert( std::to_underlying(e1) == 1 );
  37   static_assert( std::to_underlying((E)3) == 3 );
  38 }