* [Bug testsuite/101782] [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729
2021-08-04 20:23 [Bug testsuite/101782] New: [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729 seurer at gcc dot gnu.org
@ 2021-08-04 21:21 ` redi at gcc dot gnu.org
2021-08-04 22:29 ` [Bug c++/101782] " redi at gcc dot gnu.org
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From: redi at gcc dot gnu.org @ 2021-08-04 21:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101782
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2021-08-04
Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org
Ever confirmed|0 |1
Status|UNCONFIRMED |ASSIGNED
Target Milestone|--- |12.0
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug c++/101782] [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729
2021-08-04 20:23 [Bug testsuite/101782] New: [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729 seurer at gcc dot gnu.org
2021-08-04 21:21 ` [Bug testsuite/101782] " redi at gcc dot gnu.org
@ 2021-08-04 22:29 ` redi at gcc dot gnu.org
2021-08-04 22:35 ` redi at gcc dot gnu.org
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From: redi at gcc dot gnu.org @ 2021-08-04 22:29 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101782
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |rejects-valid
Assignee|redi at gcc dot gnu.org |unassigned at gcc dot gnu.org
Status|ASSIGNED |NEW
Component|testsuite |c++
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This is a C++ FE bug.
This valid C++20 code:
template<typename T> concept foo = true;
template<typename T> requires foo<T>
[[nodiscard]]
int bar(T) { return 1; }
is rejected with the -fconcepts-ts flag (as both C++20 and C++17):
conc.C:4:1: error: two consecutive ‘[’ shall only introduce an attribute before
‘[’ token
4 | [[nodiscard]]
| ^
For C++17 mode, -fconcepts-ts defines __cpp_concepts=201507L so we could use
that to suppress the [[nodiscard]] attributes when the flag is given.
But we can't detect it for C++20 mode (which is when the testsuite errors
happen) because C++20 defines __cpp_concepts=201907L and -fconcepts-ts doesn't
change that. So I'm not sure what we can do, other than not apply the attribute
to constrained functions with a requires-clause.
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug c++/101782] [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729
2021-08-04 20:23 [Bug testsuite/101782] New: [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729 seurer at gcc dot gnu.org
2021-08-04 21:21 ` [Bug testsuite/101782] " redi at gcc dot gnu.org
2021-08-04 22:29 ` [Bug c++/101782] " redi at gcc dot gnu.org
@ 2021-08-04 22:35 ` redi at gcc dot gnu.org
2021-08-05 10:31 ` [Bug testsuite/101782] " redi at gcc dot gnu.org
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From: redi at gcc dot gnu.org @ 2021-08-04 22:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101782
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think we can probably do this to stop the test failing:
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-pr67774.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr67774.C
@@ -1,5 +1,4 @@
// { dg-do compile { target c++20 } }
-// { dg-additional-options "-fconcepts-ts" }
#include <type_traits>
#include <utility>
Because that flag was present to enable concepts support, but concepts are
always enabled for c++20 now, and it gets run with -std=c++2a
But the FE bug still needs to be fixed.
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug testsuite/101782] [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729
2021-08-04 20:23 [Bug testsuite/101782] New: [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729 seurer at gcc dot gnu.org
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2021-08-04 22:35 ` redi at gcc dot gnu.org
@ 2021-08-05 10:31 ` redi at gcc dot gnu.org
2021-08-05 11:14 ` jakub at gcc dot gnu.org
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From: redi at gcc dot gnu.org @ 2021-08-05 10:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101782
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org
Keywords|rejects-valid |
Component|c++ |testsuite
Depends on| |68061
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The FE bug is PR 68061.
Changing component back to testsuite so this bug is only about the failing
test, not the FE bug.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68061
[Bug 68061] Can't use [[deprecated]] with requires clause
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug testsuite/101782] [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729
2021-08-04 20:23 [Bug testsuite/101782] New: [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729 seurer at gcc dot gnu.org
` (3 preceding siblings ...)
2021-08-05 10:31 ` [Bug testsuite/101782] " redi at gcc dot gnu.org
@ 2021-08-05 11:14 ` jakub at gcc dot gnu.org
2021-08-05 14:17 ` [Bug libstdc++/101782] " cvs-commit at gcc dot gnu.org
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From: jakub at gcc dot gnu.org @ 2021-08-05 11:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101782
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #1)
> This is a C++ FE bug.
>
> This valid C++20 code:
>
> template<typename T> concept foo = true;
>
> template<typename T> requires foo<T>
> [[nodiscard]]
> int bar(T) { return 1; }
>
> is rejected with the -fconcepts-ts flag (as both C++20 and C++17):
>
> conc.C:4:1: error: two consecutive ‘[’ shall only introduce an attribute
> before ‘[’ token
> 4 | [[nodiscard]]
> | ^
>
> For C++17 mode, -fconcepts-ts defines __cpp_concepts=201507L so we could use
> that to suppress the [[nodiscard]] attributes when the flag is given.
>
> But we can't detect it for C++20 mode (which is when the testsuite errors
> happen) because C++20 defines __cpp_concepts=201907L and -fconcepts-ts
> doesn't change that. So I'm not sure what we can do, other than not apply
> the attribute to constrained functions with a requires-clause.
This is because with -fconcepts-ts the requires-clause argument is parsed as
logical-or-expression rather than constraint-logical-or-expression and for the
former the [ could be part of postfix-expression in there. Bet that is the
reason why constraint-logical-or-expression exists and allows only
primary-expressions mixed with ||s and &&s.
Perhaps the FE could have a hack, set some parser flag when parsing
requires-clause and in postfix-expression parsing if that flag is set instead
of the [[ error in there pretend [ is not there and ends the expression.
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug libstdc++/101782] [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729
2021-08-04 20:23 [Bug testsuite/101782] New: [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729 seurer at gcc dot gnu.org
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2021-08-05 11:14 ` jakub at gcc dot gnu.org
@ 2021-08-05 14:17 ` cvs-commit at gcc dot gnu.org
2021-08-05 14:28 ` redi at gcc dot gnu.org
2021-08-05 18:01 ` cvs-commit at gcc dot gnu.org
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From: cvs-commit at gcc dot gnu.org @ 2021-08-05 14:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101782
--- Comment #5 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:7b1de3eb9ed3f8dde54732d88520292c5ad1157d
commit r12-2766-g7b1de3eb9ed3f8dde54732d88520292c5ad1157d
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Aug 5 13:34:00 2021 +0100
libstdc++: Move attributes that follow requires-clauses [PR101782]
As explained in the PR, the grammar in the Concepts TS means that a [
token following a requires-clause is parsed as part of the
logical-or-expression rather than the start of an attribute. That makes
the following ill-formed when using -fconcepts-ts:
template<typename T> requires foo<T> [[nodiscard]] int f(T);
This change moves all attributes that follow a requires-clause to the
end of the function declarator.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/101782
* include/bits/ranges_base.h (ranges::begin, ranges::end)
(ranges::rbegin, ranges::rend, ranges::size, ranges::ssize)
(ranges::empty, ranges::data): Move attribute to the end of
the declarator.
* include/bits/stl_iterator.h (__gnu_cxx::__normal_iterator)
(common_iterator): Likewise for non-member operator functions.
* include/std/ranges (views::all, views::filter)
(views::transform, views::take, views::take_while, views::drop)
(views::drop_while, views::join, views::lazy_split)
(views::split, views::counted, views::common, views::reverse)
(views::elements): Likewise.
* testsuite/std/ranges/access/101782.cc: New test.
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug libstdc++/101782] [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729
2021-08-04 20:23 [Bug testsuite/101782] New: [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729 seurer at gcc dot gnu.org
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2021-08-05 14:17 ` [Bug libstdc++/101782] " cvs-commit at gcc dot gnu.org
@ 2021-08-05 14:28 ` redi at gcc dot gnu.org
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From: redi at gcc dot gnu.org @ 2021-08-05 14:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101782
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed by changing the library headers.
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug libstdc++/101782] [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729
2021-08-04 20:23 [Bug testsuite/101782] New: [12 regression] Excess errors in g++.dg/cpp2a/concepts-pr67774.C after r12-2729 seurer at gcc dot gnu.org
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@ 2021-08-05 18:01 ` cvs-commit at gcc dot gnu.org
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From: cvs-commit at gcc dot gnu.org @ 2021-08-05 18:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101782
--- Comment #7 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:c8b024fa4b76bfd914e96dd3cecfbb6ee8e91316
commit r12-2773-gc8b024fa4b76bfd914e96dd3cecfbb6ee8e91316
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Aug 5 16:46:00 2021 +0100
libstdc++: Move [[nodiscard]] attributes again [PR101782]
Where I moved these nodiscard attributes to made them apply to the
function type, not to the function. This meant they no longer generated
the desired -Wunused-result warnings, and were ill-formed with Clang
(but only a pedwarn with GCC).
Clang also detected ill-formed attributes in <queue> which this fixes.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/101782
* include/bits/ranges_base.h (ranges::begin, ranges::end)
(ranges::rbegin, ranges::rend, ranges::size, ranges::ssize)
(ranges::empty, ranges::data): Move attribute after the
declarator-id instead of at the end of the declarator.
* include/bits/stl_iterator.h (__gnu_cxx::__normal_iterator):
Move attributes back to the start of the function declarator,
but move the requires-clause to the end.
(common_iterator): Move attribute after the declarator-id.
* include/bits/stl_queue.h (queue): Remove ill-formed attributes
from friend declaration that are not definitions.
* include/std/ranges (views::all, views::filter)
(views::transform, views::take, views::take_while,
views::drop) (views::drop_while, views::join,
views::lazy_split) (views::split, views::counted,
views::common, views::reverse) (views::elements): Move
attributes after the declarator-id.
^ permalink raw reply [flat|nested] 9+ messages in thread