Re: [gentoo-dev] GLEP: gentoo sync based unified deps proposal

[Brian Harring <ferringb@gmail.com>]

On Tue, Sep 18, 2012 at 08:48:16AM +0200, hasufell wrote:
> I am unsure if that does or could solve the problem why GLEP 62 was
> created, meaning... would enabling the "foo" useflag after the package
> has been emerged trigger a remerge in the following example?
> 
> DEPENDENCIES="
> 	dep:run? (
> 		foo? ( dev-libs/foobar )
> 	)"

Just transfering over the discussion from IRC, tbh hadn't thought 
about it till you mentioned it since it has some potential flaws 
that aren't necessarily recoverable.

Specifically, what happens if to enable dev-libs/foobar support, 
something has to be done at build time?  Think about a systemd use 
flag, where the script just installs some configuration for systemd; 
that's not toggable.

It's not obvious till you trace the implications through, but w/ 
those issues what you wind up with at that point is trying to 
classify use flags, ala glep62; see the past complete-ass-ripping of 
that proposal for why it doesn't fly.

Just adding another; ebuild devs are completely up shit creek if the 
flag induces a build time effect in one spot, and controls optional 
deps in another section of the dep tree.

If someone sees a way to make that work, have at it, although to be 
clear any such notion I'm intentionally leaving out of my proposal 
since I don't see a way to do it without an explicit dep labeling.

~harring