gdb::optional unit tests

I thought I'd add some unit tests to make sure gdb::optional behaved
correctly, and started writing some, but then thought/realized that
libstdc++ already has extensive testing for C++17 std::optional, which
gdb::optional is a subset of, and thought why bother writing something
from scratch.  So I tried copying over a subset of libstdc++'s tests
(that ones that cover the subset supported by gdb::optional), and was
positively surprised that they mostly work OOTB.  This did help shake
out a few bugs from what I was implementing in the previous patch to
gdb::optional.  Still, it's a good chunk of code being copied over, so
if people dislike this copying/duplication, I can drop this patch.

gdb/ChangeLog:
2017-04-18  Pedro Alves  <palves@redhat.com>

	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
	unittests/optional-selftests.c.
	(SUBDIR_UNITTESTS_OBS): Add optional-selftests.o.
	* unittests/optional-selftests.c: New file.
	* unittests/optional/assignment/1.cc: New file.
	* unittests/optional/assignment/2.cc: New file.
	* unittests/optional/assignment/3.cc: New file.
	* unittests/optional/assignment/4.cc: New file.
	* unittests/optional/assignment/5.cc: New file.
	* unittests/optional/assignment/6.cc: New file.
	* unittests/optional/assignment/7.cc: New file.
	* unittests/optional/cons/copy.cc: New file.
	* unittests/optional/cons/default.cc: New file.
	* unittests/optional/cons/move.cc: New file.
	* unittests/optional/cons/value.cc: New file.
	* unittests/optional/in_place.cc: New file.
	* unittests/optional/observers/1.cc: New file.
	* unittests/optional/observers/2.cc: New file.

1 files changed, 124 insertions, 0 deletions

diff --git a/gdb/unittests/optional/cons/move.cc b/gdb/unittests/optional/cons/move.cc
new file mode 100644
index 0000000..5a50b08
--- /dev/null
+++ b/gdb/unittests/optional/cons/move.cc
@@ -0,0 +1,124 @@
+// Copyright (C) 2013-2017 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 copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+namespace cons_move {
+
+struct tracker
+{
+  tracker(int value) : value(value) { ++count; }
+  ~tracker() { --count; }
+
+  tracker(tracker const& other) : value(other.value) { ++count; }
+  tracker(tracker&& other) : value(other.value)
+  {
+    other.value = -1;
+    ++count;
+  }
+
+  tracker& operator=(tracker const&) = default;
+  tracker& operator=(tracker&&) = default;
+
+  int value;
+
+  static int count;
+};
+
+int tracker::count = 0;
+
+struct exception { };
+
+struct throwing_move
+{
+  throwing_move() = default;
+  throwing_move(throwing_move const&) { throw exception {}; }
+};
+
+void test()
+{
+  // [20.5.4.1] Constructors
+
+  {
+    gdb::optional<long> o;
+    auto moved_to = std::move(o);
+    VERIFY( !moved_to );
+    VERIFY( !o );
+  }
+
+  {
+    const long val = 0x1234ABCD;
+    gdb::optional<long> o { gdb::in_place, val};
+    auto moved_to = std::move(o);
+    VERIFY( moved_to );
+    VERIFY( *moved_to == val );
+    VERIFY( o && *o == val );
+  }
+
+  {
+    gdb::optional<tracker> o;
+    auto moved_to = std::move(o);
+    VERIFY( !moved_to );
+    VERIFY( tracker::count == 0 );
+    VERIFY( !o );
+  }
+
+  {
+    gdb::optional<tracker> o { gdb::in_place, 333 };
+    auto moved_to = std::move(o);
+    VERIFY( moved_to );
+    VERIFY( moved_to->value == 333 );
+    VERIFY( tracker::count == 2 );
+    VERIFY( o && o->value == -1 );
+  }
+
+  enum outcome { nothrow, caught, bad_catch };
+
+  {
+    outcome result = nothrow;
+    gdb::optional<throwing_move> o;
+
+    try
+    {
+      auto moved_to = std::move(o);
+    }
+    catch(exception const&)
+    { result = caught; }
+    catch(...)
+    { result = bad_catch; }
+
+    VERIFY( result == nothrow );
+  }
+
+  {
+    outcome result = nothrow;
+    gdb::optional<throwing_move> o { gdb::in_place };
+
+    try
+    {
+      auto moved_to = std::move(o);
+    }
+    catch(exception const&)
+    { result = caught; }
+    catch(...)
+    { result = bad_catch; }
+
+    VERIFY( result == caught );
+  }
+
+  VERIFY( tracker::count == 0 );
+}
+
+} // namespace cons_move