public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug c++/95578] New: std::ranges::copy and std::views::take_while don't want to play together
@ 2020-06-08 15:11 gcc-bugs at marehr dot dialup.fu-berlin.de
2020-06-09 3:31 ` [Bug c++/95578] " ppalka at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: gcc-bugs at marehr dot dialup.fu-berlin.de @ 2020-06-08 15:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95578
Bug ID: 95578
Summary: std::ranges::copy and std::views::take_while don't
want to play together
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gcc-bugs at marehr dot dialup.fu-berlin.de
Target Milestone: ---
Hi gcc-team,
the following code does not compile (10.1.0 and trunk)
```c++
#include <ranges>
#include <algorithm>
int main()
{
std::vector<int> v{};
// auto && rng = v; // does work
auto && rng = v | std::views::take_while([](auto &&){return true;}); //
does not work
std::vector<int> rng_copy{};
std::ranges::copy(rng, std::back_inserter(rng_copy));
return 0;
}
```
https://godbolt.org/z/nmRQgo
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/95578] std::ranges::copy and std::views::take_while don't want to play together
2020-06-08 15:11 [Bug c++/95578] New: std::ranges::copy and std::views::take_while don't want to play together gcc-bugs at marehr dot dialup.fu-berlin.de
@ 2020-06-09 3:31 ` ppalka at gcc dot gnu.org
2020-06-10 19:24 ` [Bug libstdc++/95578] " ppalka at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: ppalka at gcc dot gnu.org @ 2020-06-09 3:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95578
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2020-06-09
Status|UNCONFIRMED |ASSIGNED
Ever confirmed|0 |1
CC| |ppalka at gcc dot gnu.org
--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Confirmed. When writing the normal/reverse/move iterator optimizations for the
ranges algos, I wrongly assumed that if the begin() of a range is a
normal_iterator (or reverse_iterator, or move_iterator) then the end() must be,
too. But as this testcase shows, it's perfectly valid to have a range whose
begin() is a normal_iterator but its end() is not. So these optimizations
should check that the iterator and sentinel have the same type before
proceeding.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/95578] std::ranges::copy and std::views::take_while don't want to play together
2020-06-08 15:11 [Bug c++/95578] New: std::ranges::copy and std::views::take_while don't want to play together gcc-bugs at marehr dot dialup.fu-berlin.de
2020-06-09 3:31 ` [Bug c++/95578] " ppalka at gcc dot gnu.org
@ 2020-06-10 19:24 ` ppalka at gcc dot gnu.org
2020-06-10 22:01 ` cvs-commit at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: ppalka at gcc dot gnu.org @ 2020-06-10 19:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95578
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |10.2
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/95578] std::ranges::copy and std::views::take_while don't want to play together
2020-06-08 15:11 [Bug c++/95578] New: std::ranges::copy and std::views::take_while don't want to play together gcc-bugs at marehr dot dialup.fu-berlin.de
2020-06-09 3:31 ` [Bug c++/95578] " ppalka at gcc dot gnu.org
2020-06-10 19:24 ` [Bug libstdc++/95578] " ppalka at gcc dot gnu.org
@ 2020-06-10 22:01 ` cvs-commit at gcc dot gnu.org
2020-06-11 11:54 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-06-10 22:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95578
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:
https://gcc.gnu.org/g:a73051a0ea9ce8281e748a74dd924a6eb8fb3723
commit r11-1186-ga73051a0ea9ce8281e748a74dd924a6eb8fb3723
Author: Patrick Palka <ppalka@redhat.com>
Date: Wed Jun 10 17:37:53 2020 -0400
libstdc++: Fix some ranges algos optimizations [PR95578]
ranges::copy and a number of other ranges algorithms have unwrapping
optimizations for iterators of type __normal_iterator, move_iterator and
reverse_iterator. But in the checks that guard these optimizations we
currently only test that the iterator of the iterator/sentinel pair has
the appropriate type before proceeding with the corresponding
optimization, and do not also test the sentinel type.
This breaks the testcase in this PR because this testcase constructs via
range adaptors a range whose begin() is a __normal_iterator and whose
end() is a custom sentinel type, and then performs ranges::copy on it.
From there we bogusly perform the __normal_iterator unwrapping
optimization on this iterator/sentinel pair, which immediately leads to
a constraint failure since the custom sentinel type does not model
sentinel_for<int*>.
This patch fixes this issue by refining each of the problematic checks
to also test that the iterator and sentinel types are the same before
applying the corresponding unwrapping optimization. Along the way, some
code simplifications are made.
libstdc++-v3/ChangeLog:
PR libstdc++/95578
* include/bits/ranges_algo.h (__lexicographical_compare_fn):
Also check that the iterator and sentinel have the same type before
applying the unwrapping optimization for __normal_iterator.
Split the check into two, one for the first iterator/sentinel
pair and another for second iterator/sentinel pair. Remove uses
of __niter_base, and remove uses of std::move on a
__normal_iterator.
* include/bits/ranges_algobase.h (__equal_fn): Likewise.
(__copy_or_move): Likewise. Perform similar adjustments for
the reverse_iterator and move_iterator optimizations. Inline
the checks into the if-constexprs, and use using-declarations to
make them less visually noisy. Remove uses of __niter_wrap.
(__copy_or_move_backward): Likewise.
* testsuite/25_algorithms/copy/95578.cc: New test.
* testsuite/25_algorithms/copy_backward/95578.cc: New test.
* testsuite/25_algorithms/equal/95578.cc: New test.
* testsuite/25_algorithms/lexicographical_compare/95578.cc: New
test.
* testsuite/25_algorithms/move/95578.cc: New test.
* testsuite/25_algorithms/move_backward/95578.cc: New test.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/95578] std::ranges::copy and std::views::take_while don't want to play together
2020-06-08 15:11 [Bug c++/95578] New: std::ranges::copy and std::views::take_while don't want to play together gcc-bugs at marehr dot dialup.fu-berlin.de
` (2 preceding siblings ...)
2020-06-10 22:01 ` cvs-commit at gcc dot gnu.org
@ 2020-06-11 11:54 ` cvs-commit at gcc dot gnu.org
2020-06-11 11:55 ` ppalka at gcc dot gnu.org
2020-06-11 14:32 ` gcc-bugs at marehr dot dialup.fu-berlin.de
5 siblings, 0 replies; 7+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-06-11 11:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95578
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:
https://gcc.gnu.org/g:3e9261f0e013108135bf09f0f91b279b9c5cbd9e
commit r10-8271-g3e9261f0e013108135bf09f0f91b279b9c5cbd9e
Author: Patrick Palka <ppalka@redhat.com>
Date: Wed Jun 10 17:37:53 2020 -0400
libstdc++: Fix some ranges algos optimizations [PR95578]
ranges::copy and a number of other ranges algorithms have unwrapping
optimizations for iterators of type __normal_iterator, move_iterator and
reverse_iterator. But in the checks that guard these optimizations we
currently only test that the iterator of the iterator/sentinel pair has
the appropriate type before proceeding with the corresponding
optimization, and do not also test the sentinel type.
This breaks the testcase in this PR because this testcase constructs via
range adaptors a range whose begin() is a __normal_iterator and whose
end() is a custom sentinel type, and then performs ranges::copy on it.
From there we bogusly perform the __normal_iterator unwrapping
optimization on this iterator/sentinel pair, which immediately leads to
a constraint failure since the custom sentinel type does not model
sentinel_for<int*>.
This patch fixes this issue by refining each of the problematic checks
to also test that the iterator and sentinel types are the same before
applying the corresponding unwrapping optimization. Along the way, some
code simplifications are made.
libstdc++-v3/ChangeLog:
PR libstdc++/95578
* include/bits/ranges_algo.h (__lexicographical_compare_fn):
Also check that the iterator and sentinel have the same type before
applying the unwrapping optimization for __normal_iterator.
Split the check into two, one for the first iterator/sentinel
pair and another for second iterator/sentinel pair. Remove uses
of __niter_base, and remove uses of std::move on a
__normal_iterator.
* include/bits/ranges_algobase.h (__equal_fn): Likewise.
(__copy_or_move): Likewise. Perform similar adjustments for
the reverse_iterator and move_iterator optimizations. Inline
the checks into the if-constexprs, and use using-declarations to
make them less visually noisy. Remove uses of __niter_wrap.
(__copy_or_move_backward): Likewise.
* testsuite/25_algorithms/copy/95578.cc: New test.
* testsuite/25_algorithms/copy_backward/95578.cc: New test.
* testsuite/25_algorithms/equal/95578.cc: New test.
* testsuite/25_algorithms/lexicographical_compare/95578.cc: New
test.
* testsuite/25_algorithms/move/95578.cc: New test.
* testsuite/25_algorithms/move_backward/95578.cc: New test.
(cherry picked from commit a73051a0ea9ce8281e748a74dd924a6eb8fb3723)
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/95578] std::ranges::copy and std::views::take_while don't want to play together
2020-06-08 15:11 [Bug c++/95578] New: std::ranges::copy and std::views::take_while don't want to play together gcc-bugs at marehr dot dialup.fu-berlin.de
` (3 preceding siblings ...)
2020-06-11 11:54 ` cvs-commit at gcc dot gnu.org
@ 2020-06-11 11:55 ` ppalka at gcc dot gnu.org
2020-06-11 14:32 ` gcc-bugs at marehr dot dialup.fu-berlin.de
5 siblings, 0 replies; 7+ messages in thread
From: ppalka at gcc dot gnu.org @ 2020-06-11 11:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95578
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #4 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 10.2+, thanks for the bug report.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/95578] std::ranges::copy and std::views::take_while don't want to play together
2020-06-08 15:11 [Bug c++/95578] New: std::ranges::copy and std::views::take_while don't want to play together gcc-bugs at marehr dot dialup.fu-berlin.de
` (4 preceding siblings ...)
2020-06-11 11:55 ` ppalka at gcc dot gnu.org
@ 2020-06-11 14:32 ` gcc-bugs at marehr dot dialup.fu-berlin.de
5 siblings, 0 replies; 7+ messages in thread
From: gcc-bugs at marehr dot dialup.fu-berlin.de @ 2020-06-11 14:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95578
--- Comment #5 from gcc-bugs at marehr dot dialup.fu-berlin.de ---
Thank you for the quick response and quick fix :)
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-06-11 14:32 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-08 15:11 [Bug c++/95578] New: std::ranges::copy and std::views::take_while don't want to play together gcc-bugs at marehr dot dialup.fu-berlin.de
2020-06-09 3:31 ` [Bug c++/95578] " ppalka at gcc dot gnu.org
2020-06-10 19:24 ` [Bug libstdc++/95578] " ppalka at gcc dot gnu.org
2020-06-10 22:01 ` cvs-commit at gcc dot gnu.org
2020-06-11 11:54 ` cvs-commit at gcc dot gnu.org
2020-06-11 11:55 ` ppalka at gcc dot gnu.org
2020-06-11 14:32 ` gcc-bugs at marehr dot dialup.fu-berlin.de
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).