[v3 PATCH] Make optional::reset noexcept, make optional::value work in constant expressions.

[Jonathan Wakely]

On 29/09/16 17:22 +0300, Ville Voutilainen wrote:
>--- /dev/null
>+++ b/libstdc++-v3/testsuite/20_util/optional/observers/6.cc
>@@ -0,0 +1,39 @@
>+// { dg-options "-std=gnu++17" }
>+// { dg-do run }
>+
>+// Copyright (C) 2016 Free Software Foundation, Inc.
>+//
>+// This file is part of the GNU ISO C++ Library.  This library is free
>+// software; you can redistribute it and/or modify it under the
>+// terms of the GNU General Public License as published by the
>+// Free Software Foundation; either version 3, or (at your option)
>+// any later version.
>+
>+// This library is distributed in the hope that it will be useful,
>+// but WITHOUT ANY WARRANTY; without even the implied warranty of
>+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>+// GNU General Public License for more details.
>+
>+// You should have received a moved_to of the GNU General Public License along
>+// with this library; see the file COPYING3.  If not see
>+// <http://www.gnu.org/licenses/>.
>+
>+#include <optional>
>+#include <testsuite_hooks.h>
>+
>+struct Y
>+{
>+  constexpr int test() & {return 7;}
>+};
>+
>+constexpr int
>+test()
>+{
>+  std::optional<Y> opt{Y{}};
>+  return opt.value().test();
>+}
>+
>+int main()
>+{
>+  static_assert(test());
>+}

Can this second test use { dg-do compile } instead?

OK for trunk either way.