[ghc-steering-committee] #571: -Wsevere, Shepherd: Adam (rec: accept)

[Simon Marlow]

On Mon, 9 Oct 2023 at 15:22, Joachim Breitner <mail at joachim-breitner.de>
wrote:

>
> That is my understanding, yes.  Oleg, who suggested this originally (I
> just wrote it up) says (see motivation section of the proposal)
>
> > not having -Wsevere=missing-methods by default essentially prevents
> > any (true) breakage assessment of adding new, non-defaulted members
> > to existing type-classes.
>

If the goal is to do a breakage assessment, couldn't you make the change to
your library and then build all of Hackage with
`--ghc-option=-Werror=severe`?

Cheers
Simon



> > Wouldn't this be something that PVP should guard against? Adding new
> > fields should result in a new major version, because
> > it's technically a breaking change?
>
> Yeah, probably in a world where everyone follows the PVP perfectly, we
> wouldn’t have this discussion.
>
> Am Montag, dem 09.10.2023 um 14:38 +0100 schrieb Chris Dornan:
> > If I understand you rightly, you are arguing that any legacy packages
> > that would flag severe warnings should now fail to compile, even if
> > they are marked as being (say) Haskell2010?
>
> I’m not arguing that we should do this, but I am arguing that this is
> the question we are supposed to decide here. (I’m personally not
> decided
>
> > If the impetus for the proposal was driven by observed problematic
> > failures of packaged code that could be caught by these warnings
> > then, for me, there would be a discussion to be had.
>
> My understanding, based on the motivation section, is that this _is_
> the impetus.
>
> Cheers,
> Joachim
>
>
> --
> Joachim Breitner
>   mail at joachim-breitner.de
>   http://www.joachim-breitner.de/
>
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