Re: [gentoo-dev] pkg_pretend USE validation and VALID_USE alternative

[Brian Harring <ferringb@gmail.com>]

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On Thu, Apr 01, 2010 at 12:23:42PM +0100, Ciaran McCreesh wrote:
> On Thu, 1 Apr 2010 03:59:54 -0700
> Brian Harring <ferringb@gmail.com> wrote:
> > On Thu, Apr 01, 2010 at 12:42:10PM +0200, Gilles Dartiguelongue wrote:
> > > > Basically, you want the PM to lie to the ebuild in some fashion.  
> > > > Since pkg_pretend is free form, it's effectively impossible to
> > > > cover the scenarios it could check on- consider checking the
> > > > kernel config/version, or checking the active jvm/python version.
> > > 
> > > except the kernel will not change during the upgrade,
> > 
> > Pardon, I wasn't clear- I was referring to kernel sources, not 
> > the running kernel.
> 
> But if the kernel sources symlink is changed by installing new kernel
> sources, there won't be a valid .config in the new directory anyway.

Oddly enough, I actually have an ebuild that directly contradicts 
that- used for managing my sources w/in kvms.

> Thus, pkg_pretend doesn't introduce any new breakage.

Regardless of my own usage, ironically you just inadvertantly pointed 
out a whole class of false negatives pkg_pretend has.

Specifically, 

1) starting w/ a configured kernel at /usr/src/linux
2) merging a version of aufs2 requiring new kernel sources
3) emerge runs pkg_pretend.  aufs2 does it's checks w/in pkg_pretend, 
sees the old configured kernel and thinks things are fine
4) new kernel sources get merged.  /usr/src/linux is no lnger a 
configured kernel.
5) aufs2 blows up during its build due to an unconfigured 
kernel.

Since I'm in the mood for a Scooby Doo quote, "wraut-wroh".

~harring

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