[Bug c++/102357] The type specified by explicitly defaulted special member function that is different with it should have had is well-formed

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102357

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-09-16
     Ever confirmed|0                           |1

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to jim x from comment #0)
> There are no requirements to let implementations report an diagnosis, let

Implementations are always permitted to issue diagnostics (as warnings) for any
code.

> alone make the program ill-formed. A warning is sufficient here.

A warning is a diagnostic, so you're contradicting yourself.

The code is not ill-formed in C++20, so the implementation should "accept and
correctly execute" it ([intro.compliance.general] p2). So confirmed as a bug.

https://gcc.gnu.org/projects/cxx-status.html says that GCC 9 implemented
P0641R2, but apparently missed this bit.