Re: git-cherry-pick(1) -- path

[Alejandro Colomar <alx@kernel.org>]

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Hi Phillip, Junio,

On Fri, May 10, 2024 at 10:03:31AM GMT, Junio C Hamano wrote:
> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
> >>>      $ git format-patch --stdout -1 $ThatCommit -- $ThisPath |
> >>>        git am -3
> >> Hmmm, I hadn't thought of that; very interesting!
> >> Although I have some concerns with git-am(1); basically that it's
> >> almost
> >> clueless when there's a conflict.
> >
> > "git am -3" should be fine here as you're guaranteed to have the
> > necessary blobs available to create conflicts - this is what "git
> > rebase --apply" does.
> 
> Good thing to point out.  "am -3" is just as good for this purpose
> and "almost clueless" is a derogatory comment that requires an
> apology ;-)

Huh, I am quite surprised by `git am -3`.  I've tried it just now, and
it's amazing.  I certainly must apologize.  :-)

I tried it yesterday, but the patches were from a different repo, and
not available locally, so it really didn't do anything.  But now I tried
it within the same repo, and it's really nice!

> > As far as the implementation goes I haven't thought too deeply but I
> > suspect we'd want to create a couple of trees based on the commit we
> > want to cherry-pick and its parent filtered by the pathspec and use
> > those in the tree-way merge with HEAD.
> 
> If we were to use the ort machinery, it may not be too bad to use
> the pathspec only at the final writeout phase.  That is, perform a
> full cherry-pick in the in-core index, reset all the entries in the
> in-core index back to HEAD that are outside the given pathspec, and
> then write out the result to the working tree.  That way, an old
> change that was made to paths at the original location can be cherry
> picked to a much newer tree after these paths have been moved to a
> different location.  Doing the same with the recursive machinery
> would be missier but perhaps the more recent merge-tree that uses
> the ort machinery to work purely in-core might be a good way to go.

I didn't understand the last part well, but I guess I may do when I
start researching into it.  :)

Apart from <builtin/revert.c>, do you recommend I look into any
particular files?

Thanks!

And have a lovely weekend!
Alex


-- 
<https://www.alejandro-colomar.es/>
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