On Fri, 2019-09-20 at 12:41 -0400, Mike Gilbert wrote:
> On Fri, Sep 20, 2019 at 12:11 PM Michał Górny <mgorny@gentoo.org> wrote:
> > On Fri, 2019-09-20 at 11:46 -0400, Mike Gilbert wrote:
> > > Recently, a large number of bugs were filed against packages that have
> > > USE flag names which contain underscores. Apparently PMS prohibits
> > > this except when the USE flag is part of a USE_EXPAND variable.
> > > 
> > > https://projects.gentoo.org/pms/7/pms.html#x1-200003.1.4
> > > 
> > > I'm not certain when this text was added to PMS, or how many of the
> > > affected USE flags pre-date this policy.
> > > 
> > > Portage seems to have no issue dealing with underscores, so this
> > > doesn't seem to be solving any technical problem.
> > > 
> > > I am pretty sure that renaming a bunch of USE flags will cause some
> > > amount of end-user confusion, for very little benefit. Is enforcing
> > > this part of PMS really worth it?
> > 
> > And having packages with pretended-USE_EXPAND-that-does-not-work-as-
> > USE_EXPAND is less confusing to the users?
> 
> I doubt users immediately think "USE_EXPAND" when they see an underscore.
> 
> Portage's seems fairly unambiguous to me. For example:
> 
> % emerge -pv1O app-misc/foo
> 
> These are the packages that would be merged, in order:
> 
> [ebuild  N     ] app-misc/foo-0::local  USE="-modern_kernel"
> PYTHON_TARGETS="python3_7" VIDEO_CARDS="radeon" 0 KiB
> 
> Total: 1 package (1 new), Size of downloads: 0 KiB
> 
> I don't think anyone would mistake "modern_kernel" for a USE_EXPAND
> value  given the above.
> 

Look at the humongous list of flags on dev-libs/aws-sdk-cpp.  They all
start with 'aws_targets' which is a clear attempt to emulate USE_EXPAND.
Expect that they won't work as USE_EXPAND, user typing:

  AWS_TARGETS="foo bar baz"

will just wildly confused, and in the end this prefixing is just silly
and causes the flag names to become awfully long.

-- 
Best regards,
Michał Górny