libstdc++-v3/testsuite/18_support/coroutines/lwg3460.cc

   1 // Copyright (C) 2020-2023 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++2a" }
  19 // { dg-do compile { target c++2a } }
  20
  21 #include <coroutine>
  22
  23 void
  24 test01()
  25 {
  26   // LWG 3460. Unimplementable noop_coroutine_handle guarantees
  27
  28   static_assert( std::is_convertible_v<std::noop_coroutine_handle&,
  29                                        std::coroutine_handle<>> );
  30   static_assert( ! std::is_convertible_v<std::noop_coroutine_handle&,
  31                                          std::coroutine_handle<>&> );
  32   static_assert( ! std::is_assignable_v<std::noop_coroutine_handle&,
  33                                         std::coroutine_handle<>> );
  34
  35   std::noop_coroutine_handle h = std::noop_coroutine();
  36   std::coroutine_handle<> h2 = h;
  37   h2();         // no-op
  38   h2.resume();  // no-op
  39   h2.destroy(); // no-op
  40 }
  41
  42 void
  43 test02()
  44 {
  45   // LWG 3469. Precondition of coroutine_handle::promise may be insufficient
  46
  47   struct P1 { };
  48   struct P2 { };
  49
  50   static_assert( ! std::is_assignable_v<std::coroutine_handle<P1>&,
  51                                         std::coroutine_handle<>> );
  52   static_assert( ! std::is_assignable_v<std::coroutine_handle<P1>&,
  53                                         std::coroutine_handle<P2>> );
  54 }