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.

2 files changed, 66 insertions, 0 deletions

diff --git a/gdb/unittests/optional/observers/1.cc b/gdb/unittests/optional/observers/1.cc
new file mode 100644
index 00000000000..6c8677e0f0e
--- /dev/null
+++ b/gdb/unittests/optional/observers/1.cc
@@ -0,0 +1,31 @@
+// 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 observers_1 {
+
+struct value_type
+{
+  int i;
+};
+
+void test()
+{
+  gdb::optional<value_type> o { value_type { 51 } };
+  VERIFY( (*o).i == 51 );
+}
+
+} // namespace observers_1
diff --git a/gdb/unittests/optional/observers/2.cc b/gdb/unittests/optional/observers/2.cc
new file mode 100644
index 00000000000..3af49e67f14
--- /dev/null
+++ b/gdb/unittests/optional/observers/2.cc
@@ -0,0 +1,35 @@
+// 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 observers_2 {
+
+struct value_type
+{
+  int i;
+};
+
+void* operator&(const value_type&) = delete;
+
+void test()
+{
+  gdb::optional<value_type> o { value_type { 51 } };
+  VERIFY( o->i == 51 );
+  VERIFY( o->i == (*o).i );
+  VERIFY( &o->i == &(*o).i );
+}
+
+} // namespace observers_2