Dnia 2014-07-31, o godz. 22:17:59
Rich Freeman <rich0@gentoo.org> napisał(a):

> On Thu, Jul 31, 2014 at 3:12 PM, Michał Górny <mgorny@gentoo.org> wrote:
> >
> > Yes, exactly. We need to get dynamic-deps right if they are ever
> > supposed to become the default. That's one of the reasons that we want
> > to revert the problematic changes and make Portage use the default
> > model once again.
> 
> Do we actually have some kind of list of issues with dynamic deps?
> The only specific one that I think I've seen is with prerm and subslot
> deps, but as was pointed out that issue actually is as much of a
> problem with static deps unless you unmerge all the reverse-deps
> before upgrading anything, followed by a re-merge.

I already listed the major issues in my second reply to Michael. And I
forgot about prerm() again, thanks for adding it :).

> > If you are really curious, I am working hard on providing tools to fix
> > the vdb inconsistencies caused by dynamic-deps. There were no specific
> > data because it wasn't available until today.
> >
> > My regularly updated desktop system (2-3 days between @world updates)
> > after disabling dynamic-deps has 77 packages needing rebuild. That
> > number includes a few virtuals, Perl packages and other low-effort
> > cases. And this is after the big, scary virtual/*udev changes.
> >
> > Over the next days I will obviously have more numbers. More
> > specifically, the number of packages needing rebuild after dependency
> > changes made by developers. It should be noted that the above number
> > includes one-time rebuild of packages that are simply ancient.
> >
> > There is a lot of FUD about unnecessary rebuilds. Sadly, most people
> > seem to fight a holy war against them without realizing the real
> > impact. In fact, more unnecessary rebuilds are caused by unnecessary
> > USE flags than by dependency changes. Yet the same people believe in
> > adding more flags to contain even more minor aspects of packages...
> 
> Thank you for this.  It is very helpful in gauging the likely impact
> of having more revbumps.
> 
> One thing I don't want to do is create a barrier to anybody who wants
> to upgrade an eclass or do work on virtuals.  I can just imagine
> endless debates about whether splitting a virtual is worth it since it
> will cause up to 250 rebuilds, etc.
> 
> Is there any easy way to compare tree vs installed deps using the API?

Not an easy way. However, if you take the two patches I posted on
gentoo-portage-dev [1,2] you can play a bit with @changed-deps. You can
add a few pprint()s to the '!=' clause to see what diffs it is seeing
after preprocessing.

However, it will see some 'extra' changes from || ( foo bar:= )
to || ( foo:= bar:= ) due to weird portage behavior. This vdb records
will be fixed after rebuilding the relevant packages thanks to patch
[2].

[1]:http://article.gmane.org/gmane.linux.gentoo.portage.devel/4357
[2]:http://article.gmane.org/gmane.linux.gentoo.portage.devel/4358

-- 
Best regards,
Michał Górny