On 27/07/2021 22:00, Junio C Hamano wrote:
Junio C Hamano <gitster@xxxxxxxxx> writes:
Phillip Wood <phillip.wood123@xxxxxxxxx> writes:
This will break git-rebase--preserve-merges.sh which uses
GIT_CHERRY_PICK_HELP to set the help and ensure CHERRY_PICK_HEAD is
removed when picking commits.
Ahh, I didn't realize we still had scripted rebase backends that
called cherry-pick as an executable. I was hoping that all rebase
backends by now would be calling into the cherry-pick machinery
directly, bypassing cmd_cherry_pick(), and that was why I suggested
to catch stray one the end-users set manually in the environment
and clear it there.
I'm a bit confused as to what the
problem is - how is 'git cherry-pick' being run with
GIT_CHERRY_PICK_HELP set in the environment outside of a rebase (your
explanation in [1] does not mention how GIT_CHERRY_PICK_HELP is set)?
I didn't press for the information too hard, but I guessed that it
was perhaps because somebody like stackoverflow suggested to set a
message in their environment to get a "better message."
A good way forward may be to relieve sequencer.c::print_advice() of
the responsibility of optinally removing CHERRY_PICK_HEAD; make it a
separate function that bases its decision on a more direct cue, not
on the presense of a custom message in GIT_CHERRY_PICK_HELP, make
do_pick_commit(), which is the sole caller of print_advice(), call
it after calling print_advice().
I do not offhand know what that "direct cue" should be, but we may
already have an appropriate field in the replay_opts structure;
"replay.action is neither REVERT nor PICK" could be a good enough
approximation, I dunno.
Otherwise we can allocate a new bit in the structure, have relevant
callers set it, and teach cherry-pick an unadvertised command line
option that sets the bit, and use that option only from
git-rebase--preserve-merges when it makes a call to cherry-pick.
When "rebase -p" is either retired or rewritten in C, we can retire
the option from cherry-pick.
Workable?
Most of the time the builtin rebase should not be writing
CHERRY_PICK_HEAD in the first place (it needs it when a commit becomes
empty but not otherwise). For 'rebase -p' adding a command line option
to cherry-pick as you suggest is probably the cleanest solution - in the
short term 'rebase -i' could set it until we refactor the code that
creates CHERRY_PICK_HEAD. One thing to note is that I think
GIT_CHERRY_PICK_HELP was introduced to allow assist scripted rebase like
porcelains rather than as a way to allow users to customize the help and
setting it has always removed CHERRY_PICK_HEAD. There are however no
users of GIT_CHERRY_PICK_HELP on codesearch.debian.org
Best Wishes
Phillip
