libstdc++-v3/testsuite/20_util/underlying_type/requirements/typedefs-3.cc

   1 // Copyright (C) 2019-2024 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 // Test for SFINAE-friendly underlying_type
  23
  24 template<typename T, typename = typename std::underlying_type<T>::type>
  25   constexpr bool is_enum(int) { return true; }
  26
  27 template<typename T>
  28   constexpr bool is_enum(...) { return false; }
  29
  30 void
  31 test01()
  32 {
  33   enum E { };
  34   static_assert( is_enum<E>(0), "");
  35
  36   static_assert( !is_enum<void>(0), "");
  37   static_assert( !is_enum<int>(0), "");
  38   static_assert( !is_enum<long>(0), "");
  39   static_assert( !is_enum<int*>(0), "");
  40   static_assert( !is_enum<int[]>(0), "");
  41   static_assert( !is_enum<const int*>(0), "");
  42   static_assert( !is_enum<const int&>(0), "");
  43   static_assert( !is_enum<int()>(0), "");
  44   static_assert( !is_enum<int(&)()>(0), "");
  45   static_assert( !is_enum<int(*)()>(0), "");
  46   struct S { };
  47   static_assert( !is_enum<S>(0), "");
  48   static_assert( !is_enum<S&>(0), "");
  49   static_assert( !is_enum<S*>(0), "");
  50   static_assert( !is_enum<int S::*>(0), "");
  51   static_assert( !is_enum<int (S::*)()>(0), "");
  52 }