Subject: Re: Gerrit, GitButler, and Jujutsu projects collaborating on change-id commit footer

From: "Theodore Ts'o" <[email-masked]>
Date: Fri, 4 Apr 2025 22:09:18 -0400

On Thu, Apr 03, 2025 at 10:31:08PM +0200, Remo Senekowitsch wrote:
> > So as a cauaionary note, as people use Change ID's in Gerrit today,
> > sometimes the Change ID changes between rebases, and I've certainly
> > seen cases where the sematic meaning of the commit has changed
> > significantly without changing the Change ID.  So it's great as a
> > hint, but in practice, at least today, it might not be completely safe
> > to assume the semantics are as advertised....
> 
> That is all true. I would just say that some change-ids not being unique
> doesn't systematically take away from the benefits. If a given change-id
> is unique, you get all the benefits for that patch, independent of
> the uniqueness of the other change-ids. If some patch changes a lot
> semantically while keeping its change-id, that will degrade its review
> history, but without affecting the review history of any other patch.

Oh, agreed.  I've certainly used a Change-ID by pasting it into the
Gerrit Search Box, and when I saw two or three unrelated commits where
the one-line subject were for entirely different kernel subsystem, as
a human I could do the disambiguation myself.  And if I did't find a
particular bug fix for the various release brances, I would cut and
paste the one-line commit summary into the Gerrit Search Box, and find
the right commit, again aided by human intelligence.

So I'm super-glad that it's there, and it *is* useful.  But I just
wanted to inject a note of caution if people were thinking about using
it in some kind of automated tooling --- especilly if there is a
proposal to inject this into git as a first-class object.

Certainly from a git perspective, I will admit that more often than
not, I generally don't do something like "git log --grep
I23e218cd964f16c0b2b26127d4a5ca6529867673", but rather, "git log
--grep 'mediatek: Don't modify spi_transfer'".  If I have to cut and
paste a Change-ID, most of the time I aso have access to the one-line
commit description, and grepping for something human readable is just
easier.

					- Ted