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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/99402] [10 Regression] std::copy creates _GLIBCXX_DEBUG false positive for attempt to subscript a dereferenceable (start-of-sequence) iterator
Date: Tue, 13 Apr 2021 20:51:27 +0000 [thread overview]
Message-ID: <bug-99402-4-as6hsGBZpL@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-99402-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99402
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[10/11 Regression] |[10 Regression] std::copy
|std::copy creates |creates _GLIBCXX_DEBUG
|_GLIBCXX_DEBUG false |false positive for attempt
|positive for attempt to |to subscript a
|subscript a dereferenceable |dereferenceable
|(start-of-sequence) |(start-of-sequence)
|iterator |iterator
--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This was fixed on trunk by r11-8100:
libstdc++: [_GLIBCXX_DEBUG] Fix management of __dp_sign_max_size [PR 99402]
__dp_sign precision indicates that we found out what iterator comes first or
last in the range. __dp_sign_max_size is the same plus it gives the information
of the max size of the range that is to say the max_size value such that
distance(lhs, rhs) < max_size.
Thanks to this additional information we are able to tell when a copy of n
elements
to that range will fail even if we do not know exactly how large it is.
This patch makes sure that we are properly using this information.
libstdc++-v3/ChangeLog:
PR libstdc++/99402
* include/debug/helper_functions.h (__can_advance(_InputIterator,
const std::pair<_Diff, _Distance_precision>&, int)): New.
(__can_advance(const _Safe_iterator<>&,
const std::pair<_Diff, _Distance_precision>&, int)): New.
* include/debug/macros.h (__glibcxx_check_can_increment_dist): New,
use latter.
(__glibcxx_check_can_increment_range): Adapt to use latter.
(__glibcxx_check_can_decrement_range): Likewise.
* include/debug/safe_iterator.h
(_Safe_iterator<>::_M_can_advance(const std::pair<_Diff,
_Distance_precision>&,
int)): New.
(__can_advance(const _Safe_iterator<>&,
const std::pair<_Diff, _Distance_precision>&, int)): New.
* include/debug/safe_iterator.tcc
(_Safe_iterator<>::_M_can_advance(const std::pair<_Diff,
_Distance_precision>&,
int)): New.
(_Safe_iterator<>::_M_valid_range(const _Safe_iterator<>&,
std::pair<difference_type, _Distance_precision>&, bool)): Adapt for
__dp_sign_max_size.
(__copy_move_a): Adapt to use __glibcxx_check_can_increment_dist.
(__copy_move_backward_a): Likewise.
(__equal_aux): Likewise.
* include/debug/stl_iterator.h (__can_advance(const
std::reverse_iterator<>&,
const std::pair<_Diff, _Distance_precision>&, int)): New.
(__can_advance(const std::move_iterator<>&,
const std::pair<_Diff, _Distance_precision>&, int)): New.
* testsuite/25_algorithms/copy/debug/99402.cc: New test.
next prev parent reply other threads:[~2021-04-13 20:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-05 9:09 [Bug c++/99402] New: " kip at thevertigo dot com
2021-03-05 12:16 ` [Bug libstdc++/99402] [10/11 Regression] " redi at gcc dot gnu.org
2021-03-05 12:30 ` redi at gcc dot gnu.org
2021-03-05 12:33 ` redi at gcc dot gnu.org
2021-03-05 12:40 ` redi at gcc dot gnu.org
2021-03-05 12:55 ` redi at gcc dot gnu.org
2021-03-05 12:59 ` redi at gcc dot gnu.org
2021-03-05 19:26 ` fdumont at gcc dot gnu.org
2021-03-05 20:00 ` kip at thevertigo dot com
2021-04-08 12:02 ` rguenth at gcc dot gnu.org
2021-04-08 12:53 ` rguenth at gcc dot gnu.org
2021-04-13 20:51 ` redi at gcc dot gnu.org [this message]
2021-04-13 22:19 ` [Bug libstdc++/99402] [10 " kip at thevertigo dot com
2021-04-13 22:45 ` redi at gcc dot gnu.org
2021-04-23 12:02 ` fdumont at gcc dot gnu.org
2021-04-23 13:04 ` redi at gcc dot gnu.org
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