Re: [gentoo-dev] Re: useflag policies

[Alexis Ballier]

On Wed, 12 Aug 2015 11:30:39 -0400
Ian Stakenvicius <axs@g.o> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
>
> On 12/08/15 11:08 AM, Ulrich Mueller wrote:
> >>>>>> On Wed, 12 Aug 2015, Alexis Ballier wrote:
> >
> >> i.e. something that really tells the PM how to automate the
> >> choice: - 'qt5 -> !qt4' is rather straightforward to solve and
> >> tells the PM how (note that it is not equivalent to 'qt4 ->
> >> !qt5') - '^^ ( qt5 qt4 )' requires the PM to make a choice in
> >> order to automate it
> >
> > I was thinking about some syntax like this:
> >
> > REQUIRED_USE="|| ( +foo bar ) ^^ ( +qt5 -qt4 )"
> >
> > The package manager would first evaluate each group in
> > REQUIRED_USE with the original set of USE flags. If that doesn't
> > evaluate to true, retry with flags changed as indicated by the +
> > and - signs.
> >
> > Ulrich
> >
>
> Having the ability for REQUIRED_USE to provide a default resolution
> path should definitely help with things; I assume this is meant to
> do its work via --autounmask-write or similar, ie to help users
> adjust their config files?  Or was the thought to allow PMs to
> override USE immediately?


I think it is better seen as a list of implications, esp. for this kind
of questions :)
With that in mind, there is no autounmask-write: effective USE for a
given package is input USE with these implications applied.

> Questions:
>
> 1 - how does +foo in REQUIRED_USE relate to use-defaults set in IUSE?

This questions remains. I see use-defaults in IUSE as part of "input
USE" above.


[...]
> 3 - will having REQUIRED_USE be able to force flags on (and others
> off) likely result in abuse of profiles and other use defaults?  I
> forsee this being a way, for instance, for a dev to get around users
> setting USE="-*" in make.conf to ensure a default use flag setting
> is honoured.

How?

> 4 - Will a change to which flag the '+' is on likely to require a
> revbump for VDB updates?  For something like '^^ ( +qt4 qt5 )' I
> could see maintainers wanting to switch which flag is default across
> a bunch of packages at once when, say, the qt team wants qt5 to
> become the de-facto default.

It'll "require" a rebuild for those whose default changes anyway. I'd
say no revbump since we don't revbump all affected packages when we add
default enabled flags to make.defaults.


Alexis.