On wto, 2017-05-30 at 04:30 +1200, Kent Fredric wrote: > On Mon, 29 May 2017 17:33:13 +0200 > Michał Górny <mgo...@gentoo.org> wrote: > > > Automatically solving USE constraints solve all three fore-mentioned > > issues with REQUIRED_USE. By default, no user intervention is required > > to solve USE constraints and package.use needs to be modified only to > > enforce a non-standard solutons > > Overall I like the proposal, but one question: How do you envisage > automatic use-constraints interacting with --newuse? > > I have this feeling that "automatically enabled" flags could somehow > have an ephemeral nature, where a flag would be enabled at build time, > and then later a subsequent change in the graph toggles the flag off, > creating a potentially undesirable rebuild. > > I feel I might be imagining a problem because I might have a wire > crossed somewhere, so some sort of confirmation that I'm the insane one > and this can't happen would be reassuring :)
I might be missing something but I don't think there would be any problems that we don't have right now. To the contrary, this proposal specifically reduces the amount of USE flag changes possible as flags can be more strongly bound to valid sets only. That said, the code running --newuse/--changed-use would probably need to account for the constraints, i.e. include them in calculating the effective set of USE flags. However, it's not much different from handling use.force/use.mask, and all the metadata is in place, so it shouldn't impact performance noticeably. -- Best regards, Michał Górny
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