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* [Bug c++/107598] New: implicitly-defined copy/move assignment op not constexpr
@ 2022-11-09 19:26 mpolacek at gcc dot gnu.org
2022-11-16 13:27 ` [Bug c++/107598] " jason at gcc dot gnu.org
2022-11-16 14:09 ` mpolacek at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2022-11-09 19:26 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107598
Bug ID: 107598
Summary: implicitly-defined copy/move assignment op not
constexpr
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mpolacek at gcc dot gnu.org
Target Milestone: ---
The following test is rejected with:
bug1.C: In function ‘constexpr void g()’:
bug1.C:11:7: error: call to non-‘constexpr’ function ‘S& S::operator=(const
S&)’
11 | b = a;
| ^
bug1.C:5:4: note: ‘S& S::operator=(const S&)’ is not usable as a ‘constexpr’
function because:
5 | S& S::operator=(const S&) = default;
| ^
...because what?
I think it should be accepted, at least in C++23, because
[class.copy.assign]/10:
"A copy/move assignment operator for a class X that is defaulted and not
defined as deleted is implicitly defined when it is odr-used ([basic.def.odr])
(e.g., when it is selected by overload resolution to assign to an object of its
class type), when it is needed for constant evaluation ([expr.const]), or when
it is explicitly defaulted after its first declaration.
The implicitly-defined copy/move assignment operator is constexpr."
Here it is explicitly defaulted after its first declaration.
struct S {
constexpr S() {}
S& operator=(const S&);
};
S& S::operator=(const S&) = default;
constexpr void
g ()
{
S a, b;
b = a;
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/107598] implicitly-defined copy/move assignment op not constexpr
2022-11-09 19:26 [Bug c++/107598] New: implicitly-defined copy/move assignment op not constexpr mpolacek at gcc dot gnu.org
@ 2022-11-16 13:27 ` jason at gcc dot gnu.org
2022-11-16 14:09 ` mpolacek at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: jason at gcc dot gnu.org @ 2022-11-16 13:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107598
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jason at gcc dot gnu.org
--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> ---
It's not constexpr because it wasn't declared to be constexpr (or defaulted) in
the class body, and "If any declaration of a function or function template has
a constexpr or consteval specifier, then all its declarations shall contain the
same specifier." The wording (and the error) could use some clarification.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/107598] implicitly-defined copy/move assignment op not constexpr
2022-11-09 19:26 [Bug c++/107598] New: implicitly-defined copy/move assignment op not constexpr mpolacek at gcc dot gnu.org
2022-11-16 13:27 ` [Bug c++/107598] " jason at gcc dot gnu.org
@ 2022-11-16 14:09 ` mpolacek at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2022-11-16 14:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107598
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Keywords|rejects-valid |
Last reconfirmed| |2022-11-16
Status|UNCONFIRMED |NEW
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Ah, thanks. Then it's a diagnostic-only PR, we should still explain what the
problem is.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-11-16 14:09 UTC | newest]
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2022-11-09 19:26 [Bug c++/107598] New: implicitly-defined copy/move assignment op not constexpr mpolacek at gcc dot gnu.org
2022-11-16 13:27 ` [Bug c++/107598] " jason at gcc dot gnu.org
2022-11-16 14:09 ` mpolacek at gcc dot gnu.org
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