Re: [gentoo-dev] Pre-GLEP RFC: Automated enforcing of REQUIRED_USE constraints

[Ciaran McCreesh]

On Sat, 8 Jul 2017 16:14:09 +0200
Alexis Ballier <aballier@g.o> wrote:
> On Sat, 8 Jul 2017 13:01:39 +0100
> Ciaran McCreesh <ciaran.mccreesh@××××××××××.com> wrote:
> > On Sat, 8 Jul 2017 13:49:56 +0200
> > Alexis Ballier <aballier@g.o> wrote:
> > > On Sat, 8 Jul 2017 12:26:59 +0200
> > > Ulrich Mueller <ulm@g.o> wrote:
> > > > | * An any-of group (||) evaluates to true if at least one of
> > > > the | items in it evaluates to true.
> > > > | * An exactly-one-of group (^^) evaluates to true if exactly
> > > > one of | the items in it evaluates to true, and all the
> > > > remaining items | evaluate to false.
> > > > | * An at-most-one-of group (??) evaluates to true if at most
> > > > one of | the items in it evaluates to true.
> > > >
> > > > It should be added that any empty group (|| or ^^ or ??)
> > > > evalutates to true, because that's what PMS specifies:
> > > > https://projects.gentoo.org/pms/6/pms.html#x1-780008.2
> > >
> > > A bit OT, but that is *definitely* counter intuitive. What's the
> > > rationale and usecase behind this ?
> >
> > Annoying special cases like || ( foo? ( ... ) bar? ( ... ) ) . The
> > original reason was that old versions of Portage would simply remove
> > unmet "flag? ( )" blocks internally. It was kept in EAPI 0 because
> > stuff in the tree used it back then.
>
> Wasn't REQUIRED_USE something completely new with no prior usage in
> EAPI 3 ?

Yes, but the spec defines dependency-like structures and their meanings
once and consistently, rather than all over the place and
inconsistently.

As much as I hate the weird || ( use ? ( ) ) and empty block rules, it
would be worse to have them apply in some situations but not others.

-- 
Ciaran McCreesh