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Bug 680496

Summary: [Future EAPI] Add the ability to make the state of a particular USE flag part of the subslot
Product: Gentoo Hosted Projects Reporter: Patrick McLean <chutzpah>
Component: PMS/EAPIAssignee: PMS/EAPI <pms>
Status: CONFIRMED ---    
Severity: normal CC: esigra, ionen, mgorny, polynomial-c, sam, slyfox, zmedico
Priority: Normal    
Version: unspecified   
Hardware: All   
OS: Linux   
See Also: https://bugs.gentoo.org/show_bug.cgi?id=677292
Whiteboard:
Package list:
Runtime testing required: ---
Bug Depends on:    
Bug Blocks: 174380    

Description Patrick McLean gentoo-dev 2019-03-15 18:48:20 UTC
There are cases where USE flags change the ABI of a package (at the moment in base-system there is an issue where the "tinfo" USE flag changes the ABI of ncurses). It would be useful to be able to make the state of a particular flag be part of the subslot for a package.

I would suggest a syntax like this:

SLOT="0/6[foo]"

This would make the state of the "foo" USE flag a part of the subslot for that package, so changing the state of the flag would trigger rebuilds for all packages with a subslot dependency on the package defining the subslot.
Comment 1 Ulenrich 2019-03-15 18:57:28 UTC
Do you think of something what happened to wxGTK for example:
---
$ eshowkw  x11-libs/wxGTK
Keywords for x11-libs/wxGTK:
              |                           a     |              |  
              |                           m     |              |  
              |                           d   x |              |  
              |                           6   8 |              |  
              |                           4   6 |   u          |  
              | a a   a     p           s |   | |   n          |  
              | l m   r i   p   h m s   p f m f | e u s        | r
              | p d a m a p c x p 6 3   a b i b | a s l        | e
              | h 6 r 6 6 p 6 8 p 8 9 s r s p s | p e o        | p
              | a 4 m 4 4 c 4 6 a k 0 h c d s d | i d t        | o
--------------+---------------------------------+--------------+-------
   3.0.3      | + + + ~ + + + + + o o ~ + o ~ ~ | 6 # 3.0      | gentoo
--------------+---------------------------------+--------------+-------
   3.0.3-r300 | ~ + ~ o ~ + + + ~ o o ~ + o ~ ~ | 6 o 3.0-gtk3 | gentoo
--------------+---------------------------------+--------------+-------
[I]3.0.4      | + + + ~ + + + + + o o ~ + o ~ ~ | 6 o 3.0      | gentoo
   3.0.4-r1   | ~ ~ ~ ~ ~ ~ ~ ~ ~ o o ~ ~ o ~ ~ | 6 #          | gentoo
--------------+---------------------------------+--------------+-------
   3.0.4-r300 | ~ + ~ o ~ + + + ~ o o ~ + o ~ ~ | 6 o 3.0-gtk3 | gentoo
   3.0.4-r301 | ~ ~ ~ o ~ ~ ~ ~ ~ o o ~ ~ o ~ ~ | 6 o          | gentoo
Comment 2 Michał Górny archtester Gentoo Infrastructure gentoo-dev Security 2019-03-18 14:17:21 UTC
1. Should this really be part of the dependency and not of the dependee?  I dare say there will be packages that are unaffected by the presence of tinfo, or any similar ABI-defining flag.

2. I'm strongly against adding anything else to SLOT.  Adding subslots there was an API catastrophe enough, with 'slot' suddenly starting to mean either 'just the slot' or 'slot+subslot', depending on the context.  This should really be stored separately.

3. All those reverse dependencies are horrible but I guess we're not going to lose much, given that subslots already force the lookup.
Comment 3 Ulrich Müller gentoo-dev 2019-03-21 15:14:05 UTC
It might be more systematic to add this as another type of USE dependency in the depending package, with a meaning like "any setting of the flag is fine, but reinstall this package when the flag changes in the dependency".

Unfortunately, the "cat/foo[bar=]" syntax is already taken.
Comment 4 Michał Górny archtester Gentoo Infrastructure gentoo-dev Security 2019-03-21 15:17:51 UTC
Make it 'bar@', with @ resembling shape of a binder ;-P.
Comment 5 Ulrich Müller gentoo-dev 2019-03-21 15:49:51 UTC
(In reply to Michał Górny from comment #4)
> Make it 'bar@', with @ resembling shape of a binder ;-P.

Not possible, because @ is a legal character in USE flag names:
"A USE flag name may contain any of the characters [A-Za-z0-9+_@-]. It must begin with an alphanumeric character."
Comment 6 Sergei Trofimovich (RETIRED) gentoo-dev 2019-12-19 08:33:47 UTC
https://bugs.gentoo.org/677292 is another example of ABI dependency on gtk+[wayland]. Once gtk+'s USE=wayland is flipped off many revdeps need a rebuild.