[gentoo-dev] Re: useflag policies

[Ulrich Mueller]

>>>>> On Mon, 3 Aug 2015, Ben de Groot wrote:

> Recently some team members of the Qt project have adopted these
> ebuild policies: https://wiki.gentoo.org/wiki/Project:Qt/Policies

> I have an issue with the policy adopted under "Requires one of two
> Qt versions". In my opinion, in the case where a package offers a
> choice between qt4 or qt5, we should express this in explicit
> useflags and a REQUIRED_USE="^^ ( qt4 qt5 )". This offers the user
> the clearest choice.

> Other developers state that users are not interested in such
> implementation details, or that forced choice through REQUIRED_USE
> is too much of a hassle. This results in current ebuilds such as
> quassel to not make it clear that qt4 is an option.

The general policy is outlined here:
https://devmanual.gentoo.org/general-concepts/use-flags/index.html#conflicting-use-flags

# Note: In order to avoid forcing users to micro-manage flags too
# much, REQUIRED_USE should be used sparingly. Follow the normal
# policy whenever it is possible to do a build that will presumably
# suit the user's needs.

So I think the Qt team's policy (i.e. *no* REQUIRED_USE, prefer qt5 in
case of conflicting flags) is perfectly fine.

> This goes against the principle of least surprise, as well as
> against QA recommendations. I would like to hear specifically from
> QA about how we should proceed, but comments from the wider
> developer community are also welcome.

Maybe output an ewarn message if both qt[45] flags are set, and
therefore the qt5 default is taken?

Ulrich