libstdc++: [_GLIBCXX_DEBUG] Do not consider detached iterators as value-initialized

An attach iterator has its _M_version set to something != 0, the container version. This
value shall be preserved when detaching it so that the iterator does not look like a
value-initialized one.

libstdc++-v3/ChangeLog:

	* include/debug/formatter.h (__singular_value_init): New _Iterator_state enum entry.
	(_Parameter<>(const _Safe_iterator<>&, const char*, _Is_iterator)): Check if iterator
	parameter is value-initialized.
	(_Parameter<>(const _Safe_local_iterator<>&, const char*, _Is_iterator)): Likewise.
	* include/debug/safe_iterator.h (_Safe_iterator<>::_M_value_initialized()): New. Adapt
	checks.
	* include/debug/safe_local_iterator.h (_Safe_local_iterator<>::_M_value_initialized()): New.
	Adapt checks.
	* src/c++11/debug.cc (_Safe_iterator_base::_M_reset): Do not reset _M_version.
	(print_field(PrintContext&, const _Parameter&, const char*)): Adapt state_names.
	* testsuite/23_containers/deque/debug/iterator1_neg.cc: New test.
	* testsuite/23_containers/deque/debug/iterator2_neg.cc: New test.
	* testsuite/23_containers/forward_list/debug/iterator1_neg.cc: New test.
	* testsuite/23_containers/forward_list/debug/iterator2_neg.cc: New test.
	* testsuite/23_containers/forward_list/debug/iterator3_neg.cc: New test.

2 files changed, 77 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/23_containers/deque/debug/iterator1_neg.cc b/libstdc++-v3/testsuite/23_containers/deque/debug/iterator1_neg.cc
new file mode 100644
index 00000000000..73f8a044d43
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/deque/debug/iterator1_neg.cc
@@ -0,0 +1,37 @@
+// Copyright (C) 2022 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/>.
+//
+// { dg-do run { xfail *-*-* } }
+// { dg-require-debug-mode "" }
+
+#include <deque>
+
+void test01()
+{
+  typedef typename std::deque<int>::iterator It;
+  std::deque<int> dq;
+  dq.push_back(1);
+
+  It it = It();
+  (void)(dq.begin() != it);
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/23_containers/deque/debug/iterator2_neg.cc b/libstdc++-v3/testsuite/23_containers/deque/debug/iterator2_neg.cc
new file mode 100644
index 00000000000..0abf5cbd4ec
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/deque/debug/iterator2_neg.cc
@@ -0,0 +1,40 @@
+// Copyright (C) 2022 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/>.
+//
+// { dg-do run { xfail *-*-* } }
+// { dg-require-debug-mode "" }
+
+#include <deque>
+
+void test01()
+{
+  typedef typename std::deque<int>::iterator It;
+  It it;
+  {
+    std::deque<int> dq;
+    it = dq.begin();
+  }
+
+  It value_init_it = It();
+  (void)(it != value_init_it);
+}
+
+int main()
+{
+  test01();
+  return 0;
+}