* [Bug c++/109181] requires expression type requirement rejects valid type when it is a nested member template
2023-03-18 6:23 [Bug c++/109181] New: requires expression type requirement rejects valid type when it is a nested member template waffl3x at protonmail dot com
@ 2023-03-18 6:32 ` pinskia at gcc dot gnu.org
2023-03-18 19:34 ` waffl3x at protonmail dot com
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-18 6:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109181
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-03-18
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Known to fail| |10.1.0, 12.1.0, 13.0,
| |6.1.0, 7.1.0
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
Goes away the way back when -fconcepts support was originally added in GCC 6.
You can see that with this testcase:
```
struct A {
template<typename>
using B = int;
};
template<typename T>
bool go = requires{typename A::template B<T>;};
```
Note back in GCC 6, you needed `-std=c++17 -fconcepts` and also requires was
only allowed for templates too ..
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/109181] requires expression type requirement rejects valid type when it is a nested member template
2023-03-18 6:23 [Bug c++/109181] New: requires expression type requirement rejects valid type when it is a nested member template waffl3x at protonmail dot com
2023-03-18 6:32 ` [Bug c++/109181] " pinskia at gcc dot gnu.org
@ 2023-03-18 19:34 ` waffl3x at protonmail dot com
2023-03-20 23:28 ` ppalka at gcc dot gnu.org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: waffl3x at protonmail dot com @ 2023-03-18 19:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109181
--- Comment #2 from waffl3x <waffl3x at protonmail dot com> ---
(In reply to Andrew Pinski from comment #1)
> Confirmed.
> Goes away the way back when -fconcepts support was originally added in GCC
> 6. You can see that with this testcase:
> ```
> struct A {
> template<typename>
> using B = int;
> };
>
> template<typename T>
> bool go = requires{typename A::template B<T>;};
> ```
>
> Note back in GCC 6, you needed `-std=c++17 -fconcepts` and also requires was
> only allowed for templates too ..
Ah damn, I'll try to keep in mind that I can use the old enabling flags to go
further back. I'm glad this one wasn't a duplicate, heres hoping I don't find
another bug today
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/109181] requires expression type requirement rejects valid type when it is a nested member template
2023-03-18 6:23 [Bug c++/109181] New: requires expression type requirement rejects valid type when it is a nested member template waffl3x at protonmail dot com
2023-03-18 6:32 ` [Bug c++/109181] " pinskia at gcc dot gnu.org
2023-03-18 19:34 ` waffl3x at protonmail dot com
@ 2023-03-20 23:28 ` ppalka at gcc dot gnu.org
2023-03-20 23:51 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: ppalka at gcc dot gnu.org @ 2023-03-20 23:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109181
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ppalka at gcc dot gnu.org
--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
A workaround is to just remove the unneeded 'template' after the :: in this
case. Or is there an example where the template keyword is needed that we
incorrectly reject?
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/109181] requires expression type requirement rejects valid type when it is a nested member template
2023-03-18 6:23 [Bug c++/109181] New: requires expression type requirement rejects valid type when it is a nested member template waffl3x at protonmail dot com
` (2 preceding siblings ...)
2023-03-20 23:28 ` ppalka at gcc dot gnu.org
@ 2023-03-20 23:51 ` pinskia at gcc dot gnu.org
2023-03-22 1:00 ` waffl3x at protonmail dot com
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-20 23:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109181
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Patrick Palka from comment #3)
> A workaround is to just remove the unneeded 'template' after the :: in this
> case. Or is there an example where the template keyword is needed that we
> incorrectly reject?
I could not find an example.
I did find an example where the template is removed clang rejects it but gcc
does not:
struct A {
template<typename>
using B = int;
};
template<typename T>
T C();
template<typename T>
bool go = requires{typename decltype(C<T>())::template B<T>;};
bool a = go<int>;
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/109181] requires expression type requirement rejects valid type when it is a nested member template
2023-03-18 6:23 [Bug c++/109181] New: requires expression type requirement rejects valid type when it is a nested member template waffl3x at protonmail dot com
` (3 preceding siblings ...)
2023-03-20 23:51 ` pinskia at gcc dot gnu.org
@ 2023-03-22 1:00 ` waffl3x at protonmail dot com
2023-08-08 2:53 ` waffl3x at protonmail dot com
2023-08-09 18:10 ` ppalka at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: waffl3x at protonmail dot com @ 2023-03-22 1:00 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109181
--- Comment #5 from waffl3x <waffl3x at protonmail dot com> ---
(In reply to Patrick Palka from comment #3)
> A workaround is to just remove the unneeded 'template' after the :: in this
> case. Or is there an example where the template keyword is needed that we
> incorrectly reject?
In my original use case, A in `inline constexpr bool go = requires{typename
A::template B<int>;};` would have been dependent, I included the template
keyword because of that but it should have occurred to me that the example I
presented doesn't need it, I'm not sure what the standard requires for this
sort of thing though.
When I reduce I just remove everything that isn't required to get the result
I'm looking for, I should have realized that changing the semantics of the
example might create confusion and in the future I think I will also include a
reduced version that comes closer to the problem I actually encountered, I
imagine that it will be helpful even if it's not actually the most reduced
version.
I'll try to create an example that reflects my use case better as soon as I
can.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/109181] requires expression type requirement rejects valid type when it is a nested member template
2023-03-18 6:23 [Bug c++/109181] New: requires expression type requirement rejects valid type when it is a nested member template waffl3x at protonmail dot com
` (4 preceding siblings ...)
2023-03-22 1:00 ` waffl3x at protonmail dot com
@ 2023-08-08 2:53 ` waffl3x at protonmail dot com
2023-08-09 18:10 ` ppalka at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: waffl3x at protonmail dot com @ 2023-08-08 2:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109181
--- Comment #6 from waffl3x <waffl3x at protonmail dot com> ---
PR 110927 presents a similar use case that originally lead me to this bug, I
also posted the workarounds that I had since discovered there. If anyone coming
across this bug is looking for a solution you can find them there.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug c++/109181] requires expression type requirement rejects valid type when it is a nested member template
2023-03-18 6:23 [Bug c++/109181] New: requires expression type requirement rejects valid type when it is a nested member template waffl3x at protonmail dot com
` (5 preceding siblings ...)
2023-08-08 2:53 ` waffl3x at protonmail dot com
@ 2023-08-09 18:10 ` ppalka at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: ppalka at gcc dot gnu.org @ 2023-08-09 18:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109181
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #7 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to waffl3x from comment #6)
> PR 110927 presents a similar use case that originally lead me to this bug, I
> also posted the workarounds that I had since discovered there. If anyone
> coming across this bug is looking for a solution you can find them there.
Interesting, thanks! I'm going to call this PR a dup of the newer one then,
since that one has your workarounds.
*** This bug has been marked as a duplicate of bug 110927 ***
^ permalink raw reply [flat|nested] 8+ messages in thread