[PATCH] commit: correct advice about aborting a cherry-pick

[PATCH] commit: correct advice about aborting a cherry-pick

[Ramkumar Ramachandra]

When a cherry-pick results in an empty commit, git prints:

  The previous cherry-pick is now empty, possibly due to conflict resolution.
  If you wish to commit it anyway, use:

      git commit --allow-empty

  Otherwise, please use 'git reset'

The last line is plain wrong in the case of a ranged pick, as a 'git
reset' will fail to remove $GIT_DIR/sequencer, failing a subsequent
cherry-pick or revert.  Change the advice to:

  git cherry-pick --abort

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 Another candidate for maint?

 I'd also really like to squelch this with an advice.* variable; any
 suggestions?

 builtin/commit.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index 003bd7d..1b213f7 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -64,7 +64,10 @@ N_("The previous cherry-pick is now empty, possibly due to conflict resolution.\
 "\n"
 "    git commit --allow-empty\n"
 "\n"
-"Otherwise, please use 'git reset'\n");
+"Otherwise, use:\n"
+"\n"
+"    git cherry-pick --abort\n"
+"\n");
 
 static const char *use_message_buffer;
 static const char commit_editmsg[] = "COMMIT_EDITMSG";
-- 
1.8.4.rc0.1.g8f6a3e5.dirty

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jeff King]

On Fri, Jul 26, 2013 at 11:42:00PM +0530, Ramkumar Ramachandra wrote:

> When a cherry-pick results in an empty commit, git prints:
> 
>   The previous cherry-pick is now empty, possibly due to conflict resolution.
>   If you wish to commit it anyway, use:
> 
>       git commit --allow-empty
> 
>   Otherwise, please use 'git reset'
> 
> The last line is plain wrong in the case of a ranged pick, as a 'git
> reset' will fail to remove $GIT_DIR/sequencer, failing a subsequent
> cherry-pick or revert.  Change the advice to:
> 
>   git cherry-pick --abort

Hmm. I don't think I've run across this message myself, so perhaps I do
not understand the situation. But it seems like you would want to do one
of:

  1. Make an empty commit.

  2. Skip this commit and continue the rest of the cherry-pick sequence.

  3. Abort the cherry pick sequence.

Those are the options presented when rebase runs into an empty commit,
where (2) is presented as "rebase --skip". I'm not sure how to do that
here; is it just "cherry-pick --continue"?

>  I'd also really like to squelch this with an advice.* variable; any
>  suggestions?

This seems like a good candidate for squelching, but you would probably
want to split it. The two parts of the message are:

  1. What happened (the cherry-pick is empty).

  2. How to proceed from here (allow-empty, abort, etc).

You still want to say (1), but (2) is useless to old-timers.  Probably
something like advice.cherryPickInstructions would be a good name for an
option to squelch (2), and it should apply wherever we tell the user how
to proceed. Potentially it should even be advice.sequenceInstructions,
and apply to rebase and am as well.

-Peff

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Ramkumar Ramachandra]

Jeff King wrote:
> Hmm. I don't think I've run across this message myself, so perhaps I do
> not understand the situation.

It's very simple.

  # on branch master
  $ git checkout -b test
  $ git cherry-pick master
  $ ls .git/sequencer
  # missing

In the pseudo multi-pick case (I say "pseudo" because there's really
just one commit to pick):

  # on branch master
  $ git checkout -b test
  $ git cherry-pick master~..
  $ ls .git/sequencer

cat .git/sequencer/todo if you like.

>   2. Skip this commit and continue the rest of the cherry-pick sequence.

Nope, this is unsupported afaik.

> Those are the options presented when rebase runs into an empty commit,
> where (2) is presented as "rebase --skip". I'm not sure how to do that
> here; is it just "cherry-pick --continue"?

No, --continue will just print the same message over and over again.

Yes, the whole ranged cherry-pick thing can use a lot more polish.

>   1. What happened (the cherry-pick is empty).
>
>   2. How to proceed from here (allow-empty, abort, etc).
>
> You still want to say (1), but (2) is useless to old-timers.  Probably
> something like advice.cherryPickInstructions would be a good name for an
> option to squelch (2), and it should apply wherever we tell the user how
> to proceed. Potentially it should even be advice.sequenceInstructions,
> and apply to rebase and am as well.

Good suggestion.  I'll pick advice.cherryPickInstructions when I
decide to polish sequencer.c a bit.

Thanks.

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jeff King]

On Sat, Jul 27, 2013 at 02:47:47AM +0530, Ramkumar Ramachandra wrote:

> >   2. Skip this commit and continue the rest of the cherry-pick sequence.
> 
> Nope, this is unsupported afaik.

Ah. I don't mind improving the message in the meantime, but it sounds
like this is a deficiency in sequenced cherry-pick that needs addressed
eventually.

Your patch is just swapping out "git reset" for "cherry-pick --abort",
so I think that is a good improvement in the meantime.

-Peff

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Ramkumar Ramachandra]

Jeff King wrote:
> Ah. I don't mind improving the message in the meantime, but it sounds
> like this is a deficiency in sequenced cherry-pick that needs addressed
> eventually.

I'm especially irked by how slow rebase--am is, and want to replace it.

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jonathan Nieder]

Jeff King wrote:

> Your patch is just swapping out "git reset" for "cherry-pick --abort",
> so I think that is a good improvement in the meantime.

Um, wasn't the idea of the original message that you can run "git
reset" and then "git cherry-pick --continue"?

Confused,
Jonathan

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jeff King]

On Fri, Jul 26, 2013 at 02:37:05PM -0700, Jonathan Nieder wrote:

> Jeff King wrote:
> 
> > Your patch is just swapping out "git reset" for "cherry-pick --abort",
> > so I think that is a good improvement in the meantime.
> 
> Um, wasn't the idea of the original message that you can run "git
> reset" and then "git cherry-pick --continue"?

Maybe. :)

I missed that subtlety. Of my "three things you would want to do", that
means it was _trying_ say number 2, how to skip, rather than 3, how to
abort. If that is the case, then it should probably explain the sequence
of steps as "reset and then --continue" to make it more clear.

I.e., a patch is needed, but Ram's is going in the opposite direction.

-Peff

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jeff King]

On Fri, Jul 26, 2013 at 05:40:36PM -0400, Jeff King wrote:

> > Jeff King wrote:
> > 
> > > Your patch is just swapping out "git reset" for "cherry-pick --abort",
> > > so I think that is a good improvement in the meantime.
> > 
> > Um, wasn't the idea of the original message that you can run "git
> > reset" and then "git cherry-pick --continue"?
> 
> Maybe. :)
> 
> I missed that subtlety. Of my "three things you would want to do", that
> means it was _trying_ say number 2, how to skip, rather than 3, how to
> abort. If that is the case, then it should probably explain the sequence
> of steps as "reset and then --continue" to make it more clear.
> 
> I.e., a patch is needed, but Ram's is going in the opposite direction.

I played around a bit with the test cases that Ram showed. It seems like
the advice needed is different depending on whether you are in a single
or multi-commit cherry-pick.

So if we hit an empty commit and you want to:

  1. Make an empty commit, then always run "git commit --allow-empty".

  2. Skip this commit, then if:

     a. this is a single commit cherry-pick, you run "git reset" (and
        nothing more, the cherry pick is finished; running "cherry-pick
        --continue" will yield an error).

     b. this is a multi-commit cherry-pick, you run "git reset",
        followed by "git cherry-pick --continue"

  3. Abort the commit, run "git cherry-pick --abort"

Let's assume that the instructions we want to give the user are how to
do options 1 and 2. I do not mind omitting 3, as it should be reasonably
obvious that "cherry-pick --abort" is always good way to abort.

So we give good instructions for the single-commit case, but bad
instructions for the multi-commit case. Ram's patch suggests --abort
instead of reset, which is the same for the single-commit case, but
suggests 3 instead of 2 for the multi-patch.

I think instead we would want to leave the single-commit case alone, and
for the multi-commit case add "...and then cherry-pick --continue". That
message is generated from within git-commit, though; I guess it would
need to learn about the difference between single/multi cherry-picks.

-Peff

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jeff King]

On Fri, Jul 26, 2013 at 06:43:59PM -0400, Jeff King wrote:

> I think instead we would want to leave the single-commit case alone, and
> for the multi-commit case add "...and then cherry-pick --continue". That
> message is generated from within git-commit, though; I guess it would
> need to learn about the difference between single/multi cherry-picks.

Like this?

-- >8 --
Subject: [PATCH] commit: tweak empty cherry pick advice for sequencer

When we refuse to make an empty commit, we check whether we
are in a cherry-pick in order to give better advice on how
to proceed. We instruct the user to repeat the commit with
"--allow-empty" to force the commit, or to use "git reset"
to skip it and abort the cherry-pick.

This works fine when we are cherry-picking a single commit.
When we are using the sequencer to cherry-pick multiple
items, though, using "git reset" is not good advice. It does
not skip the commit (you must run "cherry-pick --continue"
to keep going), but nor does it abort the cherry-pick (the
.sequencer directory still exists).

Let's teach commit to tell when the sequencer is in use, and
to mention "cherry-pick --continue" in that case.

Signed-off-by: Jeff King <peff@peff.net>
---
The advice in the multi case could eventually change to "cherry-pick
--skip" if and when it exists.

 builtin/commit.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index e47f100..45a98d7 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -63,8 +63,14 @@ N_("The previous cherry-pick is now empty, possibly due to conflict resolution.\
 "If you wish to commit it anyway, use:\n"
 "\n"
 "    git commit --allow-empty\n"
+"\n");
+static const char empty_cherry_pick_advice_skip_single[] =
+N_("Otherwise, please use 'git reset'\n");
+static const char empty_cherry_pick_advice_skip_multi[] =
+N_("If you wish to skip this commit, use:\n"
 "\n"
-"Otherwise, please use 'git reset'\n");
+"    git reset && git cherry-pick --continue\n"
+"\n");
 
 static const char *use_message_buffer;
 static const char commit_editmsg[] = "COMMIT_EDITMSG";
@@ -107,6 +113,7 @@ static enum commit_whence whence;
 static const char *cleanup_arg;
 
 static enum commit_whence whence;
+static int sequencer_in_use;
 static int use_editor = 1, include_status = 1;
 static int show_ignored_in_status, have_option_m;
 static const char *only_include_assumed;
@@ -141,8 +148,11 @@ static void determine_whence(struct wt_status *s)
 {
 	if (file_exists(git_path("MERGE_HEAD")))
 		whence = FROM_MERGE;
-	else if (file_exists(git_path("CHERRY_PICK_HEAD")))
+	else if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
 		whence = FROM_CHERRY_PICK;
+		if (file_exists(git_path("sequencer")))
+			sequencer_in_use = 1;
+	}
 	else
 		whence = FROM_COMMIT;
 	if (s)
@@ -808,8 +818,15 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		run_status(stdout, index_file, prefix, 0, s);
 		if (amend)
 			fputs(_(empty_amend_advice), stderr);
-		else if (whence == FROM_CHERRY_PICK)
+		else if (whence == FROM_CHERRY_PICK) {
 			fputs(_(empty_cherry_pick_advice), stderr);
+			if (!sequencer_in_use)
+				fputs(_(empty_cherry_pick_advice_skip_single),
+				      stderr);
+			else
+				fputs(_(empty_cherry_pick_advice_skip_multi),
+				      stderr);
+		}
 		return 0;
 	}
 
-- 
1.8.3.rc1.30.gff0fb75

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jonathan Nieder]

Jeff King wrote:

> --- a/builtin/commit.c
> +++ b/builtin/commit.c
> @@ -63,8 +63,14 @@ N_("The previous cherry-pick is now empty, possibly due to conflict resolution.\
>  "If you wish to commit it anyway, use:\n"
>  "\n"
>  "    git commit --allow-empty\n"
> +"\n");
> +static const char empty_cherry_pick_advice_skip_single[] =
> +N_("Otherwise, please use 'git reset'\n");
> +static const char empty_cherry_pick_advice_skip_multi[] =
> +N_("If you wish to skip this commit, use:\n"
>  "\n"
> -"Otherwise, please use 'git reset'\n");
> +"    git reset && git cherry-pick --continue\n"
> +"\n");

Hmm, wouldn't it be more consistent to either say

	If you wish to commit it anyway, use

		git commit --allow-empty && git cherry-pick --continue

	If you wish to skip this commit, use

		git reset && git cherry-pick --continue

Or

	If you wish to commit it anyway, use

		git commit --allow-empty
	
	If you wish to skip this commit, use

		git reset

	Then "git cherry-pick --continue" will resume cherry-picking
	the remaining commits.

?

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jeff King]

On Fri, Jul 26, 2013 at 04:08:57PM -0700, Jonathan Nieder wrote:

> Jeff King wrote:
> 
> > --- a/builtin/commit.c
> > +++ b/builtin/commit.c
> > @@ -63,8 +63,14 @@ N_("The previous cherry-pick is now empty, possibly due to conflict resolution.\
> >  "If you wish to commit it anyway, use:\n"
> >  "\n"
> >  "    git commit --allow-empty\n"
> > +"\n");
> > +static const char empty_cherry_pick_advice_skip_single[] =
> > +N_("Otherwise, please use 'git reset'\n");
> > +static const char empty_cherry_pick_advice_skip_multi[] =
> > +N_("If you wish to skip this commit, use:\n"
> >  "\n"
> > -"Otherwise, please use 'git reset'\n");
> > +"    git reset && git cherry-pick --continue\n"
> > +"\n");
> 
> Hmm, wouldn't it be more consistent to either say
> 
> 	If you wish to commit it anyway, use
> 
> 		git commit --allow-empty && git cherry-pick --continue
> 
> 	If you wish to skip this commit, use
> 
> 		git reset && git cherry-pick --continue

Good point. Clearly the original assumed that you knew to "cherry-pick
--continue", since it is needed (and omitted) in both cases. And perhaps
most people do, but certainly the lack of mentioning it confused both me
and Ram about whether the "git reset" advice was meant to skip or abort.

> Or
> 
> 	If you wish to commit it anyway, use
> 
> 		git commit --allow-empty
> 	
> 	If you wish to skip this commit, use
> 
> 		git reset
> 
> 	Then "git cherry-pick --continue" will resume cherry-picking
> 	the remaining commits.

I like this one better.

You could _almost_ just use the top bit for the single-commit case, but
I hesitate to use the word "skip" in that case. Right now the
single-commit case does not need to make the distinction between "skip
this, and there is nothing else to do" and "abort the operation",
because they are the same thing.  Whichever way the user thinks about it
is OK.

-Peff

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jeff King]

On Fri, Jul 26, 2013 at 07:19:02PM -0400, Jeff King wrote:

> > Or
> > 
> > 	If you wish to commit it anyway, use
> > 
> > 		git commit --allow-empty
> > 	
> > 	If you wish to skip this commit, use
> > 
> > 		git reset
> > 
> > 	Then "git cherry-pick --continue" will resume cherry-picking
> > 	the remaining commits.
> 
> I like this one better.

Here it is in patch form, with an updated commit message that hopefully
explains the rationale a bit better.

-- >8 --
Subject: [PATCH] commit: tweak empty cherry pick advice for sequencer

When we refuse to make an empty commit, we check whether we
are in a cherry-pick in order to give better advice on how
to proceed. We instruct the user to repeat the commit with
"--allow-empty" to force the commit, or to use "git reset"
to skip it and abort the cherry-pick.

In the case of a single cherry-pick, the distinction between
skipping and aborting is not important, as there is no more
work to be done afterwards.  When we are using the sequencer
to cherry pick a series of commits, though, the instruction
is confusing: does it skip this commit, or does it abort the
rest of the cherry-pick?

It does skip, after which the user can continue the
cherry-pick. This is the right thing to be advising the user
to do, but let's make it more clear what will happen, both
by using the word "skip", and by mentioning that the rest of
the sequence can be continued via "cherry-pick --continue"
(whether we skip or take the commit).

Noticed-by: Ramkumar Ramachandra <artagnon@gmail.com>
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/commit.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index e47f100..73fafe2 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -63,8 +63,18 @@ N_("The previous cherry-pick is now empty, possibly due to conflict resolution.\
 "If you wish to commit it anyway, use:\n"
 "\n"
 "    git commit --allow-empty\n"
+"\n");
+
+static const char empty_cherry_pick_advice_single[] =
+N_("Otherwise, please use 'git reset'\n");
+
+static const char empty_cherry_pick_advice_multi[] =
+N_("If you wish to skip this commit, use:\n"
 "\n"
-"Otherwise, please use 'git reset'\n");
+"    git reset\n"
+"\n"
+"Then \"git cherry-pick --continue\" will resume cherry-picking\n"
+"the remaining commits.\n");
 
 static const char *use_message_buffer;
 static const char commit_editmsg[] = "COMMIT_EDITMSG";
@@ -107,6 +117,7 @@ static enum commit_whence whence;
 static const char *cleanup_arg;
 
 static enum commit_whence whence;
+static int sequencer_in_use;
 static int use_editor = 1, include_status = 1;
 static int show_ignored_in_status, have_option_m;
 static const char *only_include_assumed;
@@ -141,8 +152,11 @@ static void determine_whence(struct wt_status *s)
 {
 	if (file_exists(git_path("MERGE_HEAD")))
 		whence = FROM_MERGE;
-	else if (file_exists(git_path("CHERRY_PICK_HEAD")))
+	else if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
 		whence = FROM_CHERRY_PICK;
+		if (file_exists(git_path("sequencer")))
+			sequencer_in_use = 1;
+	}
 	else
 		whence = FROM_COMMIT;
 	if (s)
@@ -808,8 +822,13 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		run_status(stdout, index_file, prefix, 0, s);
 		if (amend)
 			fputs(_(empty_amend_advice), stderr);
-		else if (whence == FROM_CHERRY_PICK)
+		else if (whence == FROM_CHERRY_PICK) {
 			fputs(_(empty_cherry_pick_advice), stderr);
+			if (!sequencer_in_use)
+				fputs(_(empty_cherry_pick_advice_single), stderr);
+			else
+				fputs(_(empty_cherry_pick_advice_multi), stderr);
+		}
 		return 0;
 	}
 
-- 
1.8.3.rc1.30.gff0fb75

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Ramkumar Ramachandra]

Jeff King wrote:
>  builtin/commit.c | 25 ++++++++++++++++++++++---
>  1 file changed, 22 insertions(+), 3 deletions(-)

Overall, highly inelegant.  The single-commit pick has been special
cased only because we needed to preserve backward compatibility: I
would hate for the detail to be user-visible.  I'd have expected a
series that polishes sequencer.c instead.

But whatever.  I'm going to squelch them anyway.

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> Here it is in patch form, with an updated commit message that hopefully
> explains the rationale a bit better.
>
> -- >8 --
> Subject: [PATCH] commit: tweak empty cherry pick advice for sequencer
>
> When we refuse to make an empty commit, we check whether we
> are in a cherry-pick in order to give better advice on how
> to proceed. We instruct the user to repeat the commit with
> "--allow-empty" to force the commit, or to use "git reset"
> to skip it and abort the cherry-pick.
>
> In the case of a single cherry-pick, the distinction between
> skipping and aborting is not important, as there is no more
> work to be done afterwards.  When we are using the sequencer
> to cherry pick a series of commits, though, the instruction
> is confusing: does it skip this commit, or does it abort the
> rest of the cherry-pick?
>
> It does skip, after which the user can continue the
> cherry-pick. This is the right thing to be advising the user
> to do, but let's make it more clear what will happen, both
> by using the word "skip", and by mentioning that the rest of
> the sequence can be continued via "cherry-pick --continue"
> (whether we skip or take the commit).
>
> Noticed-by: Ramkumar Ramachandra <artagnon@gmail.com>
> Helped-by: Jonathan Nieder <jrnieder@gmail.com>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
>  builtin/commit.c | 25 ++++++++++++++++++++++---
>  1 file changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/builtin/commit.c b/builtin/commit.c
> index e47f100..73fafe2 100644
> --- a/builtin/commit.c
> +++ b/builtin/commit.c
> @@ -63,8 +63,18 @@ N_("The previous cherry-pick is now empty, possibly due to conflict resolution.\
>  "If you wish to commit it anyway, use:\n"
>  "\n"
>  "    git commit --allow-empty\n"
> +"\n");
> +
> +static const char empty_cherry_pick_advice_single[] =
> +N_("Otherwise, please use 'git reset'\n");
> +
> +static const char empty_cherry_pick_advice_multi[] =
> +N_("If you wish to skip this commit, use:\n"
>  "\n"
> -"Otherwise, please use 'git reset'\n");
> +"    git reset\n"
> +"\n"
> +"Then \"git cherry-pick --continue\" will resume cherry-picking\n"
> +"the remaining commits.\n");
>  
>  static const char *use_message_buffer;
>  static const char commit_editmsg[] = "COMMIT_EDITMSG";
> @@ -107,6 +117,7 @@ static enum commit_whence whence;
>  static const char *cleanup_arg;
>  
>  static enum commit_whence whence;
> +static int sequencer_in_use;
>  static int use_editor = 1, include_status = 1;
>  static int show_ignored_in_status, have_option_m;
>  static const char *only_include_assumed;
> @@ -141,8 +152,11 @@ static void determine_whence(struct wt_status *s)
>  {
>  	if (file_exists(git_path("MERGE_HEAD")))
>  		whence = FROM_MERGE;
> -	else if (file_exists(git_path("CHERRY_PICK_HEAD")))
> +	else if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
>  		whence = FROM_CHERRY_PICK;
> +		if (file_exists(git_path("sequencer")))
> +			sequencer_in_use = 1;

Should this be

	sequencer_in_use = file_exists(...)

so readers do not have to wonder what the variable is initialized
to?

Other than that, looks reasonable to me.  Thanks.



> +	}
>  	else
>  		whence = FROM_COMMIT;
>  	if (s)
> @@ -808,8 +822,13 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
>  		run_status(stdout, index_file, prefix, 0, s);
>  		if (amend)
>  			fputs(_(empty_amend_advice), stderr);
> -		else if (whence == FROM_CHERRY_PICK)
> +		else if (whence == FROM_CHERRY_PICK) {
>  			fputs(_(empty_cherry_pick_advice), stderr);
> +			if (!sequencer_in_use)
> +				fputs(_(empty_cherry_pick_advice_single), stderr);
> +			else
> +				fputs(_(empty_cherry_pick_advice_multi), stderr);
> +		}
>  		return 0;
>  	}

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Jeff King]

On Mon, Jul 29, 2013 at 08:18:45AM -0700, Junio C Hamano wrote:

> >  	if (file_exists(git_path("MERGE_HEAD")))
> >  		whence = FROM_MERGE;
> > -	else if (file_exists(git_path("CHERRY_PICK_HEAD")))
> > +	else if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
> >  		whence = FROM_CHERRY_PICK;
> > +		if (file_exists(git_path("sequencer")))
> > +			sequencer_in_use = 1;
> 
> Should this be
> 
> 	sequencer_in_use = file_exists(...)
> 
> so readers do not have to wonder what the variable is initialized
> to?

Yeah, I think that is a readability improvement. I suppose the use-site
could also just run "file_exists" itself, but I wanted to keep the
filesystem-reading "magic name" bits together.

I had also originally considered adding new states to "whence" to cover
these cases (i.e., FROM_CHERRY_PICK_MULTI), but there are fallouts all
over the place for call sites that do not care whether we are in the
single- or multi-commit mode.

-Peff

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> On Mon, Jul 29, 2013 at 08:18:45AM -0700, Junio C Hamano wrote:
>
>> >  	if (file_exists(git_path("MERGE_HEAD")))
>> >  		whence = FROM_MERGE;
>> > -	else if (file_exists(git_path("CHERRY_PICK_HEAD")))
>> > +	else if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
>> >  		whence = FROM_CHERRY_PICK;
>> > +		if (file_exists(git_path("sequencer")))
>> > +			sequencer_in_use = 1;
>> 
>> Should this be
>> 
>> 	sequencer_in_use = file_exists(...)
>> 
>> so readers do not have to wonder what the variable is initialized
>> to?
>
> Yeah, I think that is a readability improvement. I suppose the use-site
> could also just run "file_exists" itself, but I wanted to keep the
> filesystem-reading "magic name" bits together.

I take that one back.  The use-site is sufficiently far from this
assignment that is protected with a cascading if that the reader
needs to be aware that sequencer_in_use is initialized to zero
anyway.  The code you posted is just as readable, if not more.

> I had also originally considered adding new states to "whence" to cover
> these cases (i.e., FROM_CHERRY_PICK_MULTI), but there are fallouts all
> over the place for call sites that do not care whether we are in the
> single- or multi-commit mode.

;-)

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> On Fri, Jul 26, 2013 at 05:40:36PM -0400, Jeff King wrote:
>
>> > Jeff King wrote:
>> > 
>> > > Your patch is just swapping out "git reset" for "cherry-pick --abort",
>> > > so I think that is a good improvement in the meantime.
>> > 
>> > Um, wasn't the idea of the original message that you can run "git
>> > reset" and then "git cherry-pick --continue"?
>> 
>> Maybe. :)
>> 
>> I missed that subtlety. Of my "three things you would want to do", that
>> means it was _trying_ say number 2, how to skip, rather than 3, how to
>> abort. If that is the case, then it should probably explain the sequence
>> of steps as "reset and then --continue" to make it more clear.
>> 
>> I.e., a patch is needed, but Ram's is going in the opposite direction.
>
> I played around a bit with the test cases that Ram showed. It seems like
> the advice needed is different depending on whether you are in a single
> or multi-commit cherry-pick.
>
> So if we hit an empty commit and you want to:
>
>   1. Make an empty commit, then always run "git commit --allow-empty".
>
>   2. Skip this commit, then if:
>
>      a. this is a single commit cherry-pick, you run "git reset" (and
>         nothing more, the cherry pick is finished; running "cherry-pick
>         --continue" will yield an error).

Yes, the single-replay mode never required "cherry-pick --continue"
to clean sequencer cruft when discarding a failed cherry-pick, so it
is a natural consequence of a conscious design decision that
"cherry-pick --continue" will say "you are not running a
cherry-pick", exactly because you no longer are.

>      b. this is a multi-commit cherry-pick, you run "git reset",
>         followed by "git cherry-pick --continue"

True.

>   3. Abort the commit, run "git cherry-pick --abort"
>
> Let's assume that the instructions we want to give the user are how to
> do options 1 and 2. I do not mind omitting 3, as it should be reasonably
> obvious that "cherry-pick --abort" is always good way to abort.
>
> So we give good instructions for the single-commit case, but bad
> instructions for the multi-commit case.

Yeah, that matches what I thought.  It appears that when we did a
shoddy job when teaching commit to give this advice-message and only
considered a single-pick mode, perhaps because multi-replay mode was
relatively new back then.

> I think instead we would want to leave the single-commit case alone, and
> for the multi-commit case add "...and then cherry-pick --continue". That
> message is generated from within git-commit, though; I guess it would
> need to learn about the difference between single/multi cherry-picks.

Sounds very sensible.

Re: [PATCH] commit: correct advice about aborting a cherry-pick

[Ramkumar Ramachandra]

Jonathan Nieder wrote:
>> Your patch is just swapping out "git reset" for "cherry-pick --abort",
>> so I think that is a good improvement in the meantime.
>
> Um, wasn't the idea of the original message that you can run "git
> reset" and then "git cherry-pick --continue"?

No, and I don't know where you got that idea.  Certainly not by
reading the history.

37f7a85 (Teach commit about CHERRY_PICK_HEAD, 2011-02-19) introduced
that string.  This happened before I introduced cherry-pick --continue
in 5a5d80f (revert: Introduce --continue to continue the operation,
2011-08-04).

A proper solution to the problem would involve polishing sequencer.c,
and probably getting --skip-empty so it behaves more like rebase.  In
case you missed it, one person already did that work and posted the
code to the list [1].

[1]: http://article.gmane.org/gmane.comp.version-control.git/226982