[Bug fortran/82018] -Wextra should imply -Wconversion-extra

["tkoenig at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82018

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |tkoenig at gcc dot gnu.org

--- Comment #6 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to janus from comment #5)
> (In reply to tkoenig@netcologne.de from comment #3)
> > > Maybe one could re-enable such warnings at least with -Wextra?
> > 
> > The warning is given with -Wconversion-extra.
> > 
> > We could enable -Wconversion-extra with -Wextra.
> 
> Yes, please! Why isn't that done already? Sounds like an ideal candidate for
> -Wextra. Leaving it out certainly violates the principle of least surprise
> ...
> 
> If no one else has time for such "trivialities", I will take the time.

The patch is quite simple (just modify the relevant line
in lang.opts and update the docs).

-Wconversion-extra uncovers lots of things that people may not want to
see a warning about, such as i8=i4.

We had a lengthy discussion about this in 2015, with the current
implementation as the result.

See https://gcc.gnu.org/ml/fortran/2015-05/msg00176.html and
followups for the discussions about this.