libstdc++-v3/testsuite/20_util/optional/observers/3.cc

   1 // { dg-options "-std=gnu++17" }
   2 // { dg-do run { target c++17 }  }
   3
   4 // Copyright (C) 2013-2020 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 <optional>
  22 #include <testsuite_hooks.h>
  23
  24 struct value_type
  25 {
  26   int i;
  27 };
  28
  29 int main()
  30 {
  31   {
  32     std::optional<value_type> o { value_type { 51 } };
  33     VERIFY( o.value().i == 51 );
  34     VERIFY( o.value().i == (*o).i );
  35     VERIFY( &o.value().i == &(*o).i );
  36   }
  37
  38   {
  39     enum outcome_type { nothrow, caught, bad_catch };
  40
  41     outcome_type outcome {};
  42     std::optional<value_type> o = std::nullopt;
  43     bool called = false;
  44     auto const eat = [&called](int) { called = true; };
  45
  46     try
  47     {
  48       eat(o.value().i);
  49     }
  50     catch(std::bad_optional_access const&)
  51     { outcome = caught; }
  52     catch(...)
  53     { outcome = bad_catch; }
  54
  55     VERIFY( outcome == caught );
  56     VERIFY( !called );
  57   }
  58 }