libstdc++-v3/testsuite/23_containers/array/requirements/non_default_constructible.cc

   1 // { dg-do compile { target c++11 } }
   2 // { dg-require-effective-target rtti }
   3
   4 // Copyright (C) 2012-2025 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 // PR libstdc++/53248
  22
  23 #include <array>
  24 #include <typeindex>
  25 #include <typeinfo>
  26
  27 template < typename ...Types >
  28 union super_union;
  29
  30 template < >
  31 union super_union<>
  32 {
  33   static  auto optioned_types() -> std::array<std::type_index, 0>
  34   { return std::array<std::type_index, 0>{ {} }; }
  35 };
  36
  37 template < typename Head, typename ...Tail >
  38 union super_union<Head, Tail...>
  39 {
  40   static
  41   auto optioned_types() -> std::array<std::type_index, 1 + sizeof...(Tail)>
  42   {
  43     using std::type_index;
  44
  45     return { {type_index(typeid(Head)), type_index(typeid(Tail))...} };
  46   }
  47
  48   Head                  data;
  49   super_union<Tail...>  rest;
  50 };