Re: [gentoo-dev] Re: useflag policies

[Alexis Ballier]

On Wed, 12 Aug 2015 14:24:06 -0400
Ian Stakenvicius <axs@g.o> wrote:

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> On 12/08/15 02:19 PM, Alexis Ballier wrote:
> > On Wed, 12 Aug 2015 20:00:42 +0200 Ulrich Mueller
> > <ulm@g.o> wrote:
> >
> >>>>>>> On Wed, 12 Aug 2015, Ciaran McCreesh wrote:
> >>
> >>>> pkg_pretend() { if use qt4; then required_use -qt5 else
> >>>> required_use qt5 fi }
> >>
> >>> And how would the PM understand that -qt5 is conditional upon
> >>> qt4? Such knowledge is required if it's supposed to
> >>> auto-resolve stuff...
> >>
> >> Right, the above was too simple (and wrong). It should have
> >> been:
> >>
> >> pkg_pretend() { use qt4 && use qt5 && required_use -qt5 use qt4
> >> || use qt5 || required_use qt4 }
> >
> > what is the difference ?
> >
> > pkg_pretend still needs to be executed to guess what useflags
> > are enabled or not, which information is needed before
> > dependency calculation
> >
> > or are we talking about moving pkg_pretend into dependency
> > calculation?
> >
>
>
> pkg_pretend is already executed during dependency calculation in
> portage, although this doesn't seem to actually be specified in PMS:
> "The pkg_pretend function is called some unspecified time before a
> (possibly hypothetical) normal sequence." as per PMS sec.9.2
>

that's definitely not the impression I've got with emerge -uDNa world:
dep calculation, show result, wait for input, accept, and then
pkg_pretend stuff gets executed.