llvm dev - Sep 2019 - [RFC] changing variable naming rules

> On Sep 9, 2019, at 4:24 AM, Hans Wennborg via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> On Fri, Sep 6, 2019 at 6:17 PM Björn Pettersson A via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> I'm a little bit curious to hear more about the experiences from
the changes in LLD.
>> I’m thinking about things like:
> [..]
>> - merging of bugfixes to older release branches (I doubt that the
script supports doing the reverse rewrite as well)
> 
> As someone who does a lot of these merges, this is the aspect that
> worries me the most.

Yes, I suspect you’re personally the one who is hit the worst by this.  I’m
super sensitive to that, because I really really really want to make sure that
releases are smooth and successful.

That said, are you aware of Rui’s work on lld?  He developed a process in which
people with significant out of tree patches were able to catch up, merge the
mega patch and move forward without significant churn.  I agree it is non-zero,
but it is very low, and the cost seems worth the price of forward progress and
avoiding perpetual stagnation.

-Chris

On Tue, Sep 10, 2019 at 7:42 AM Chris Lattner <clattner at nondot.org>
wrote:
>
>
>
> > On Sep 9, 2019, at 4:24 AM, Hans Wennborg via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> >
> > On Fri, Sep 6, 2019 at 6:17 PM Björn Pettersson A via llvm-dev
> > <llvm-dev at lists.llvm.org> wrote:
> >> I'm a little bit curious to hear more about the experiences
from the changes in LLD.
> >> I’m thinking about things like:
> > [..]
> >> - merging of bugfixes to older release branches (I doubt that the
script supports doing the reverse rewrite as well)
> >
> > As someone who does a lot of these merges, this is the aspect that
> > worries me the most.
>
>
> Yes, I suspect you’re personally the one who is hit the worst by this.  I’m
super sensitive to that, because I really really really want to make sure that
releases are smooth and successful.
>
> That said, are you aware of Rui’s work on lld?  He developed a process in
which people with significant out of tree patches were able to catch up, merge
the mega patch and move forward without significant churn.  I agree it is
non-zero, but it is very low, and the cost seems worth the price of forward
progress and avoiding perpetual stagnation.
I'm not aware of exactly how that worked, but I thought Rui shared his
tool so that downstream repos could do the same conversion that
happened upstream, thereby "catching up". I don't know that
we'd want
to do that for a release branch though.

Maybe the solution for the release branches would be to time the
renaming so that it doesn't interfere with releases (e.g. do the
rename shortly before the release branch is created).

I'm not against the renaming per se, I just wanted to highlight that
this is the largest issue I see. Much of the discussion seems to have
focussed on the "git blame" issue, which I don't think is an issue
at
all.

On Sep 10, 2019, at 12:38 AM, Hans Wennborg <hans at chromium.org>
wrote:
>> That said, are you aware of Rui’s work on lld?  He developed a process
in which people with significant out of tree patches were able to catch up,
merge the mega patch and move forward without significant churn.  I agree it is
non-zero, but it is very low, and the cost seems worth the price of forward
progress and avoiding perpetual stagnation.
> 
> I'm not aware of exactly how that worked, but I thought Rui shared his
> tool so that downstream repos could do the same conversion that
> happened upstream, thereby "catching up". I don't know that
we'd want
> to do that for a release branch though.
Makes sense, I agree.
> Maybe the solution for the release branches would be to time the
> renaming so that it doesn't interfere with releases (e.g. do the
> rename shortly before the release branch is created).
+1, that would make sense to me.  Rui, what do you think about that?
> 
> I'm not against the renaming per se, I just wanted to highlight that
> this is the largest issue I see. Much of the discussion seems to have
> focussed on the "git blame" issue, which I don't think is an
issue at
> all.
Agreed. I’m pretty sure that the git blame issue is solved now, but I’m not an
expert on this at all.  I can’t wait to get from svn to GitHub though! :-) :-)

-Chris