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* [Bug libstdc++/100139] New: std::views::{take, drop} don't type erase
@ 2021-04-18 23:38 gcc-bugs at marehr dot dialup.fu-berlin.de
2021-04-19 1:04 ` [Bug libstdc++/100139] " ppalka at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: gcc-bugs at marehr dot dialup.fu-berlin.de @ 2021-04-18 23:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100139
Bug ID: 100139
Summary: std::views::{take, drop} don't type erase
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: gcc-bugs at marehr dot dialup.fu-berlin.de
Target Milestone: ---
Hello gcc-team,
the following code:
```cpp
#include <concepts>
#include <ranges>
#include <span>
#include <string_view>
static_assert(std::same_as<std::span<int>,
decltype(std::views::take(std::span<int>{}, 2))>);
static_assert(std::same_as<std::string_view,
decltype(std::views::take(std::string_view{}, 2))>);
```
does not compile (yet).
https://godbolt.org/z/6Mq7x8zaj
AFAIK this should be
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1739r0.md that was
merged by https://github.com/cplusplus/draft/pull/3777.
There was a rather amusing error report at stackoverflow [1].
I tried to find that proposal in [2] but couldn't and wanted to ask if I looked
at the wrong place. If you have time to implement this, that would be awesome!
Thank you!
[1]
https://stackoverflow.com/questions/61867635/recursive-application-of-c20-range-adaptor-causes-a-compile-time-infinite-loop
[2] https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.2020
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/100139] std::views::{take, drop} don't type erase
2021-04-18 23:38 [Bug libstdc++/100139] New: std::views::{take, drop} don't type erase gcc-bugs at marehr dot dialup.fu-berlin.de
@ 2021-04-19 1:04 ` ppalka at gcc dot gnu.org
2021-08-19 10:39 ` redi at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: ppalka at gcc dot gnu.org @ 2021-04-19 1:04 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100139
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ppalka at gcc dot gnu.org
--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Some of the wording changes of P1739 are problematic as discussed in LWG issue
3407 (https://cplusplus.github.io/LWG/lwg-active.html#3407), which is why we
don't implement it yet. Though I suppose we could at least implement the
workable parts of P1739 while waiting for the LWG issue to get resolved.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/100139] std::views::{take, drop} don't type erase
2021-04-18 23:38 [Bug libstdc++/100139] New: std::views::{take, drop} don't type erase gcc-bugs at marehr dot dialup.fu-berlin.de
2021-04-19 1:04 ` [Bug libstdc++/100139] " ppalka at gcc dot gnu.org
@ 2021-08-19 10:39 ` redi at gcc dot gnu.org
2021-08-19 12:03 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2021-08-19 10:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100139
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-08-19
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/100139] std::views::{take, drop} don't type erase
2021-04-18 23:38 [Bug libstdc++/100139] New: std::views::{take, drop} don't type erase gcc-bugs at marehr dot dialup.fu-berlin.de
2021-04-19 1:04 ` [Bug libstdc++/100139] " ppalka at gcc dot gnu.org
2021-08-19 10:39 ` redi at gcc dot gnu.org
@ 2021-08-19 12:03 ` cvs-commit at gcc dot gnu.org
2021-08-19 13:59 ` cvs-commit at gcc dot gnu.org
2021-08-19 14:08 ` cvs-commit at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-08-19 12:03 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100139
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:
https://gcc.gnu.org/g:926d4a71c7e5a2f7d17a4f943d6e7fe9f1e3ba55
commit r12-3021-g926d4a71c7e5a2f7d17a4f943d6e7fe9f1e3ba55
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Aug 19 11:44:57 2021 +0100
libstdc++: Document P1739R4 status [PR100139]
We should document the status of this unimplemented feature.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/100139
* doc/xml/manual/status_cxx2020.xml: Add P1739R4 to status table.
* doc/html/manual/status.html: Regenerate.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/100139] std::views::{take, drop} don't type erase
2021-04-18 23:38 [Bug libstdc++/100139] New: std::views::{take, drop} don't type erase gcc-bugs at marehr dot dialup.fu-berlin.de
` (2 preceding siblings ...)
2021-08-19 12:03 ` cvs-commit at gcc dot gnu.org
@ 2021-08-19 13:59 ` cvs-commit at gcc dot gnu.org
2021-08-19 14:08 ` cvs-commit at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-08-19 13:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100139
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:
https://gcc.gnu.org/g:31433e154f5eecb17151d77b259b13d41c0b8e7c
commit r11-8886-g31433e154f5eecb17151d77b259b13d41c0b8e7c
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Aug 19 11:44:57 2021 +0100
libstdc++: Document P1739R4 status [PR100139]
We should document the status of this unimplemented feature.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/100139
* doc/xml/manual/status_cxx2020.xml: Add P1739R4 to status table.
* doc/html/manual/status.html: Regenerate.
(cherry picked from commit 926d4a71c7e5a2f7d17a4f943d6e7fe9f1e3ba55)
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/100139] std::views::{take, drop} don't type erase
2021-04-18 23:38 [Bug libstdc++/100139] New: std::views::{take, drop} don't type erase gcc-bugs at marehr dot dialup.fu-berlin.de
` (3 preceding siblings ...)
2021-08-19 13:59 ` cvs-commit at gcc dot gnu.org
@ 2021-08-19 14:08 ` cvs-commit at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-08-19 14:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100139
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:
https://gcc.gnu.org/g:321ff3ad38e05096abc4de6d3bb2150cc0f75d91
commit r10-10047-g321ff3ad38e05096abc4de6d3bb2150cc0f75d91
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Aug 19 11:44:57 2021 +0100
libstdc++: Document P1739R4 status [PR100139]
We should document the status of this unimplemented feature.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/100139
* doc/xml/manual/status_cxx2020.xml: Add P1739R4 to status table.
* doc/html/manual/status.html: Regenerate.
(cherry picked from commit 926d4a71c7e5a2f7d17a4f943d6e7fe9f1e3ba55)
^ permalink raw reply [flat|nested] 6+ messages in thread
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