public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug c++/105766] New: requires std::is_constructible<> reports 'constraint depends on itself' error.
@ 2022-05-29 10:40 stream009 at gmail dot com
2022-07-19 18:05 ` [Bug c++/105766] " cvs-commit at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: stream009 at gmail dot com @ 2022-05-29 10:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105766
Bug ID: 105766
Summary: requires std::is_constructible<> reports 'constraint
depends on itself' error.
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: stream009 at gmail dot com
Target Milestone: ---
GCC reports following error on following code.
|error: satisfaction of atomic constraint 'is_constructible_v<T, int> [with T =
T]' depends on itself
First of all, I can't decipher the error message. So I guessed, maybe root of
trouble is the fact, at the time of instantiation of template baz (4), although
parameter T = foo::bar is a complete type but its surrounding type foo is not.
- If I uncomment (1), the error goes away, so it seems to become a problem only
when the constraint is on a member function.
- Also the error goes away too if I uncomment (2).
- Most interestingly, error goes away if I comment out (3).
- The code compile without error on clang.
FYI, in real code, foo is thread pool, bar is worker, baz is container.
// code
// https://godbolt.org/z/M48ssEqvr
#include <type_traits>
template<typename T>
//requires std::is_constructible_v<T, int> (1)
struct baz
{
baz() = default;
//template<typename = void> // (2)
baz(int) requires std::is_constructible_v<T, int> {}
};
struct foo
{
struct bar {
bar() = default;
bar(foo&); // (3)
bar(int);
};
baz<bar> m_bars; // (4)
};
int main()
{
foo a; (void)a;
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105766] requires std::is_constructible<> reports 'constraint depends on itself' error.
2022-05-29 10:40 [Bug c++/105766] New: requires std::is_constructible<> reports 'constraint depends on itself' error stream009 at gmail dot com
@ 2022-07-19 18:05 ` cvs-commit at gcc dot gnu.org
2022-08-01 14:36 ` ppalka at gcc dot gnu.org
2024-03-08 21:47 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-07-19 18:05 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105766
--- Comment #1 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:68f37670eff0b872ce5dfd382c8d8f3206bdfc27
commit r13-1755-g68f37670eff0b872ce5dfd382c8d8f3206bdfc27
Author: Patrick Palka <ppalka@redhat.com>
Date: Tue Jul 19 14:04:13 2022 -0400
c++: shortcut bad reference binding [PR94894]
In case of l/rvalue or cv-qual mismatch during reference binding, we
try to give more helpful diagnostics by computing a bad conversion that
allows the mismatch. But in doing so, we may end up considering and
instantiating a conversion function that could induce a hard error and
in turn cause us to reject otherwise valid code. We could just give up
on producing a better diagnostic here, but ideally we'd preserve the
better diagnostics for invalid code while avoiding unnecessary template
instantiations for valid code.
To that end, this patch adapts the bad conversion shortcutting mechanism
from r12-3346-g47543e5f9d1fc5 to additionally handle this situation.
The main observation from there is that during overload resolution, if we
know we have a strictly viable candidate then we don't need to distinguish
between an unviable and non-strictly viable candidate. Thus we don't
need to distinguish between an invalid and bad conversion either, which
is what this patch exploits. Of course, we don't know whether we have a
strictly viable candidate until after the fact, so we still need to
remember when we deferred distinguishing between an invalid and bad
conversion. This patch adds a special conversion kind ck_deferred_bad
for this purpose.
PR c++/94894
PR c++/105766
PR c++/106201
gcc/cp/ChangeLog:
* call.cc (enum conversion_kind): Add ck_deferred_bad enumerator.
(has_next): Return false for it.
(reference_binding): Return a ck_deferred_bad conversion instead
of an actual bad conversion when LOOKUP_SHORTCUT_BAD_CONVS is set.
Remove now obsolete early exit for the incomplete TO case.
(implicit_conversion_1): Don't mask out LOOKUP_SHORTCUT_BAD_CONVS.
(add_function_candidate): Set LOOKUP_SHORTCUT_BAD_CONVS iff
shortcut_bad_convs.
(missing_conversion_p): Also return true for a ck_deferred_bad
conversion.
* cp-tree.h (LOOKUP_SHORTCUT_BAD_CONVS): Define.
gcc/testsuite/ChangeLog:
* g++.dg/conversion/ref8.C: New test.
* g++.dg/conversion/ref9.C: New test.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105766] requires std::is_constructible<> reports 'constraint depends on itself' error.
2022-05-29 10:40 [Bug c++/105766] New: requires std::is_constructible<> reports 'constraint depends on itself' error stream009 at gmail dot com
2022-07-19 18:05 ` [Bug c++/105766] " cvs-commit at gcc dot gnu.org
@ 2022-08-01 14:36 ` ppalka at gcc dot gnu.org
2024-03-08 21:47 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: ppalka at gcc dot gnu.org @ 2022-08-01 14:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105766
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ppalka at gcc dot gnu.org
Resolution|--- |FIXED
Target Milestone|--- |13.0
Status|UNCONFIRMED |RESOLVED
--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 13, thanks for the bug report.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105766] requires std::is_constructible<> reports 'constraint depends on itself' error.
2022-05-29 10:40 [Bug c++/105766] New: requires std::is_constructible<> reports 'constraint depends on itself' error stream009 at gmail dot com
2022-07-19 18:05 ` [Bug c++/105766] " cvs-commit at gcc dot gnu.org
2022-08-01 14:36 ` ppalka at gcc dot gnu.org
@ 2024-03-08 21:47 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: ppalka at gcc dot gnu.org @ 2024-03-08 21:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105766
Bug 105766 depends on bug 94894, which changed state.
Bug 94894 Summary: avoidable instantiation of conversion function template during overload resolution
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94894
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-03-08 21:47 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-29 10:40 [Bug c++/105766] New: requires std::is_constructible<> reports 'constraint depends on itself' error stream009 at gmail dot com
2022-07-19 18:05 ` [Bug c++/105766] " cvs-commit at gcc dot gnu.org
2022-08-01 14:36 ` ppalka at gcc dot gnu.org
2024-03-08 21:47 ` ppalka at gcc dot gnu.org
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).