Re: [gentoo-dev] [PATCH] profiles/package.deprecated: deprecate python:2.7

[Michał Górny]

On Fri, 2020-06-26 at 17:47 +0100, Sergei Trofimovich wrote:
> On Fri, 26 Jun 2020 11:38:58 +0200
> Michał Górny <mgorny@g.o> wrote:
>
> > On Fri, 2020-06-26 at 09:51 +0100, Sergei Trofimovich wrote:
> > > On Fri, 26 Jun 2020 07:29:45 +0000
> > > Michał Górny <mgorny@g.o> wrote:
> > >
> > > > Dnia June 26, 2020 6:42:57 AM UTC, Sergei Trofimovich <slyfox@g.o> napisał(a):
> > > > > On Sat, 20 Jun 2020 16:29:53 +0100
> > > > > Sergei Trofimovich <slyfox@g.o> wrote:
> > > > >
> > > > > > On Sat, 20 Jun 2020 16:05:38 +0200
> > > > > > Michał Górny <mgorny@g.o> wrote:
> > > > > >
> > > > > > > On Sat, 2020-06-20 at 14:57 +0100, Sergei Trofimovich wrote:
> > > > > > > > Give maintainers the chance to act and flag packages that pull in
> > > > > python:2.7.
> > > > > > > > Signed-off-by: Sergei Trofimovich <slyfox@g.o>
> > > > > > > > ---
> > > > > > > >  profiles/package.deprecated | 4 ++++
> > > > > > > >  1 file changed, 4 insertions(+)
> > > > > > > >
> > > > > > > > diff --git a/profiles/package.deprecated
> > > > > b/profiles/package.deprecated
> > > > > > > > index a756e845f47..bb661571962 100644
> > > > > > > > --- a/profiles/package.deprecated
> > > > > > > > +++ b/profiles/package.deprecated
> > > > > > > > @@ -17,6 +17,10 @@
> > > > > > > >
> > > > > > > >  #--- END OF EXAMPLES ---
> > > > > > > >
> > > > > > > > +# Sergei Trofimovich <slyfox@g.o> (2020-06-20)
> > > > > > > > +# Deprecated. Consider poring to python 3 and drop support for
> > > > > python2.
> > > > > > > > +dev-lang/python:2.7
> > > > > > > > +
> > > > > > > >  # Sergei Trofimovich <slyfox@g.o> (2020-02-22)
> > > > > > > >  # virtual/libstdc++ has only one sys-libs/libstdc++-v3 provider.
> > > > > > > >  # Use that instead. Or even better use none of them. It's a
> > > > > > >
> > > > > >
> > > > > > > It will trigger the same for packages that support *only*
> > > > > > > Python 2.7, as well as these that support 2.7 in addition to 3
> > > > > because
> > > > > > > they have 2.7 deps.
> > > > > >
> > > > > > If we expect actions by developers on both cases I don't see a
> > > > > problem with that.
> > > > >
> > > > > Pushed as:
> > > > > https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=79d65d6641cfc0ef7b44df491c390e8c880e3049
> > > > > with full text being:
> > > > >
> > > > > +# Sergei Trofimovich <slyfox@g.o> (2020-06-26)
> > > > > +# Deprecated.
> > > > > +# - optional python:2.7 dependency should be dropped if no reverse
> > > > > +#   dependencies are using it.
> > > > > +# - mandatory python:2.7 depepndency will require package porting
> > > > > +#   or package removal if no reverse dependencies are using it.
> > > > > +dev-lang/python:2.7
> > > >
> > > > You've just introduced 829 CI warnings
> > >
> > > That's the intention.
> > >
> > > > effectively disabling the ability to distinguish *new* problems in these packages.
> > >
> > > Correct. Citing above:
> > >
> > > "If we expect actions by developers on both cases I don't see a  problem with that."
> > >
> > > I assume we still do.
> >
> > Not exactly.  You've pinpointed the wrong target.
> >
> > First of all, we want people to support Python 3.  Removing support for
> > Python 2 is a secondary goal.
>
> What is the desired end state here? All packages that depend on
> python should support python3?

Yes, or be masked for removal.  The desired result is that at some point
in time we can disable py2 target in eclass without anything breaking.

> > Flagging packages that support Python 2 in addition to Python 3
> > and cause no trouble in py2 cleanup is doubtful.
>
> What is "py2 cleanup"? I still struggle to understand what packages
> require change and which do not. Is there one pager doc that explains
> a few things for me:

Some of this is mentioned in Python Guide [1].

[1] https://dev.gentoo.org/~mgorny/python-guide/package-maintenance.html#support-for-python-2

> - How packages are picked for masking? Maybe we can deprecate them
>   instead? Or we (I) can write a bit of code that flags packages requiring
>   maintainers' attention.

This is really decided by humans, and I don't think it can be trivially
automated.  So far we've focused on masking packages that are either
a. unlikely to be ported (e.g. dead upstream), b. have no Gentoo
maintainers.

> - What is the expected end state for the "py2 cleanup"?

Not sure if I understand right but I think the answer is: we can disable
py2 support via eclass and nothing breaks.

> The doc would also be a good link to add to recently added "# Py2 only"
> masks as well.
>
> > Flagging packages that support 2+3 because of their revdeps is not
> > helpful at all.  It's just noise to the maintainer who can't remove py2
> > because of revdeps.
>
> I agree it can be spammy if we expect to have many packages with
> python2 support for an extended period of time (3+ months). If it's
> seen by others as too noisy I can revert the commit now.

The 'early' py2 removal date is set for 2021-01-01 AFAIR (I'm yet to
publish the timeline I've RFC-ed earlier).  Not sure if it's possible.
 One thing I'm sure of is that py2 support is becoming harder
and harder.

>
> > Flagging dev-python/pypy* which needs py2 but is entirely outside
> > the eclass system is not helpful at all.
>
> To pick a concrete example: from what I read above I don't see why
> app-misc/golly was masked for removal.

Me neither.  But I really do think this can be resolved peacefully
without neverending debates.

-- 
Best regards,
Michał Górny