Re: erroneous behavior in 2-style USE dependencies?

>>>>> On Wed, 17 Jun 2020, Michael Lienhardt wrote:

> But maybe, "error" here in the PMS mean "the cpvs without the use flag
> does not match that dependency and a warning should be raised to
> improve compatibility in the future". In that case, it would be
> clearer for me to change 'error' in the PMS into something like
> "results in a no match,

IMHO we cannot assume that. If the flag is not in the dependency's
IUSE_EFFECTIVE then behaviour is undefined.

> but should be avoided". That way, it is explicitly stated that missing
> use flags for a 2-style USE dependency is accepted (which is the
> current behavior of emerge) but frown upon, without forcing any
> specific error handling, like Michał accurately pointed out.

The real problem is that we don't have a good procedure for removing
flags from ebuilds with reverse (2-style) use dependencies. (And even
with 4-style use dependencies the problem remains that one cannot know
in advance whether removal of the flag implies that the feature is now
unconditionally enabled, or that it is disabled.)

Ulrich

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