Re: [gentoo-portage-dev] can an overlay force a USE flag on a host?

[Amit Dor-Shifer]

Zac Medico wrote:
> On 12/31/2009 06:41 AM, Amit Dor-Shifer wrote:
>
>> In cont. to my prev. question
>> (http://archives.gentoo.org/gentoo-portage-dev/msg_9973fd6c12d7c2088457697f49ea2f5e.xml)
>>
>>
>> Can I append use.force/package.use.force/package.use or similar to an
>> overlay, and by that control USE flags on the host?
>>
>
> With EAPI 1 and greater you can use IUSE="+flag" to enable flags by
> default in an ebuild.
Yes, but AFAIK, enabling a USE flag by-default only affects the enabling 
ebuild, not its dependencies. Specifically, By setting "+myflag" in an 
ebuild, I cannot incur a rebuild of a dependent which is also using this 
flag.

Appending "myflag" to the USE set via a profile would achieve that behavior.

>
>> In a/m bug, the lack of documentation in this area is mentioned . I'm
>> wondering if this has changed since those comments were written, as I'm
>> confounded by bits and pieces I'm fishing out w/google.
>>
>
> The information in the wiki seems current.
>
Would that be http://en.gentoo-wiki.com/wiki/Overlay ?
If so, then

    * your a/m comment #6 in the bug, clarifying that the 'profiles'
      directory has nothing to do with portage profiles is most valuable.

    <QUOTE>

    Don't let the directory name "profiles" make you think that it has anything to do with a profile
      

    <UNQUOTE>
    Well, it actually did make me think that. it looked plausible that
    an overlay could extend a portage profile.

    * The article also mentions "portage overlay specifications", but
      does not cite it.
    * That an overlay can extend package.[un]mask is also not mentioned
      there.

I'm currently reluctant to contribute documentation myself, since I'm 
lacking key concepts. I'd be happy to do so if I had a more thorough 
understanding.

Amit