Re: how to most effectively cherry pick by selective patch hunk?

[Jeff King <peff@peff.net>]

On Tue, Feb 09, 2021 at 08:58:06AM -0500, Robert P. J. Day wrote:

>   what would be great is some sort of "-p" (patch selection) option
> with cherry-pick, but i don't see that.

We have "checkout -p", but of course the problem there is that it's
picking out of the whole state of that commit. So you might see other
changes not introduced by that commit.

Conceptually, adding "cherry-pick -p" would be pretty easy. The strategy
for all of the "-p" options is to generate a diff, then feed that diff
to the patch-selection code, then apply whatever the user selects. For
"checkout -p $commit", that diff is the diff between $commit and our
current state. But for "cherry-pick -p", it would be the diff between
$commit^ and $commit.

Of course that involves a change to Git, and you were looking for
something you could do with existing versions. :) You can emulate it by
making the commit's parent equivalent to your current state. I.e.:

  git checkout --detach ;# detached HEAD for temporary commit
  git cherry-pick $commit ;# maybe deal with conflicts
  commit=$(git rev-parse --verify HEAD) ;# remember the temp commit
  git checkout - ;# back to your branch
  git checkout -p $commit

-Peff