threads / patch / 36205

patchgit-rebase: Teach rebase "-" shorthand.

Subject: [PATCH] git-rebase: Teach rebase "-" shorthand.

## tl;dr

12 messages between Mar 18, 2014 and Mar 19, 2014. Diffs are folded; open one to read it.

replies: 11people: 4as markdown or json

Brian Gesiak· Mar 18, 2014, 08:44 UTC · lore

Teach rebase the same shorthand as checkout and merge; that is, that "-" means "the branch we were previously on".

Reported-by: Tim Chase <git@tim.thechases.com>
Signed-off-by: Brian Gesiak <modocache@gmail.com>
---
 git-rebase.sh     | 4 ++++
 t/t3400-rebase.sh | 6 ++++++
 2 files changed, 10 insertions(+)
Show changes to 2 files +10 −0

git-rebase.sh, t/t3400-rebase.sh

diff --git a/git-rebase.sh b/git-rebase.sh
index 5f6732b..2c75e9f 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -453,6 +453,10 @@ then
 		test "$fork_point" = auto && fork_point=t
 		;;
 	*)	upstream_name="$1"
+		if test "$upstream_name" = "-"
+		then
+			upstream_name="@{-1}"
+		fi
 		shift
 		;;
 	esac
diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index 6d94b1f..00aba9f 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -88,6 +88,12 @@ test_expect_success 'rebase from ambiguous branch name' '
 	git rebase master
 '
 
+test_expect_success 'rebase using shorthand' '
+	git checkout master
+	git checkout -b shorthand HEAD^
+	GIT_TRACE=1 git rebase -
+'
+
 test_expect_success 'rebase a single mode change' '
 	git checkout master &&
 	git branch -D topic &&
-- 
1.8.5.2 (Apple Git-48)
Torsten Bögershausen· Mar 18, 2014, 19:26 UTC · re: Brian Gesiak · lore

Re: [PATCH] git-rebase: Teach rebase "-" shorthand.

On 03/18/2014 09:44 AM, Brian Gesiak wrote:
Show 35 quoted lines
> Teach rebase the same shorthand as checkout and merge; that is, that "-"
> means "the branch we were previously on".
>
> Reported-by: Tim Chase <git@tim.thechases.com>
> Signed-off-by: Brian Gesiak <modocache@gmail.com>
> ---
>   git-rebase.sh     | 4 ++++
>   t/t3400-rebase.sh | 6 ++++++
>   2 files changed, 10 insertions(+)
>
> diff --git a/git-rebase.sh b/git-rebase.sh
> index 5f6732b..2c75e9f 100755
> --- a/git-rebase.sh
> +++ b/git-rebase.sh
> @@ -453,6 +453,10 @@ then
>   		test "$fork_point" = auto && fork_point=t
>   		;;
>   	*)	upstream_name="$1"
> +		if test "$upstream_name" = "-"
> +		then
> +			upstream_name="@{-1}"
> +		fi
>   		shift
>   		;;
>   	esac
> diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
> index 6d94b1f..00aba9f 100755
> --- a/t/t3400-rebase.sh
> +++ b/t/t3400-rebase.sh
> @@ -88,6 +88,12 @@ test_expect_success 'rebase from ambiguous branch name' '
>   	git rebase master
>   '
>
> +test_expect_success 'rebase using shorthand' '
> +	git checkout master
we schould have the "&&"   ^^
> +	git checkout -b shorthand HEAD^
               we schould have the "&&"  ^^
> +	GIT_TRACE=1 git rebase -
And why the GIT_TRACE ?
Show 6 quoted lines
> +'
> +
>   test_expect_success 'rebase a single mode change' '
>   	git checkout master &&
>   	git branch -D topic &&
>
Junio C Hamano· Mar 18, 2014, 19:42 UTC · re: Brian Gesiak · lore

Re: [PATCH] git-rebase: Teach rebase "-" shorthand.

Brian Gesiak <modocache@gmail.com> writes:
Show 37 quoted lines
> Teach rebase the same shorthand as checkout and merge; that is, that "-"
> means "the branch we were previously on".
>
> Reported-by: Tim Chase <git@tim.thechases.com>
> Signed-off-by: Brian Gesiak <modocache@gmail.com>
> ---
>  git-rebase.sh     | 4 ++++
>  t/t3400-rebase.sh | 6 ++++++
>  2 files changed, 10 insertions(+)
>
> diff --git a/git-rebase.sh b/git-rebase.sh
> index 5f6732b..2c75e9f 100755
> --- a/git-rebase.sh
> +++ b/git-rebase.sh
> @@ -453,6 +453,10 @@ then
>  		test "$fork_point" = auto && fork_point=t
>  		;;
>  	*)	upstream_name="$1"
> +		if test "$upstream_name" = "-"
> +		then
> +			upstream_name="@{-1}"
> +		fi
>  		shift
>  		;;
>  	esac
> diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
> index 6d94b1f..00aba9f 100755
> --- a/t/t3400-rebase.sh
> +++ b/t/t3400-rebase.sh
> @@ -88,6 +88,12 @@ test_expect_success 'rebase from ambiguous branch name' '
>  	git rebase master
>  '
>  
> +test_expect_success 'rebase using shorthand' '
> +	git checkout master
> +	git checkout -b shorthand HEAD^
> +	GIT_TRACE=1 git rebase -

I'd rather not to see that TRACE there. We would also want to make sure the result is what we expect to see, not only the command does not error out, no?

Show 5 quoted lines
> +'
> +
>  test_expect_success 'rebase a single mode change' '
>  	git checkout master &&
>  	git branch -D topic &&
Brian Gesiak· Mar 19, 2014, 11:02 UTC · re: Junio C Hamano · lore

[PATCH v2] git-rebase: Teach rebase "-" shorthand.

Teach rebase the same shorthand as checkout and merge; that is, that "-" means "the branch we were previously on".

Reported-by: Tim Chase <git@tim.thechases.com>
Signed-off-by: Brian Gesiak <modocache@gmail.com>
---
 git-rebase.sh     |  4 ++++
 t/t3400-rebase.sh | 11 +++++++++++
 2 files changed, 15 insertions(+)
Show changes to 2 files +15 −0

git-rebase.sh, t/t3400-rebase.sh

diff --git a/git-rebase.sh b/git-rebase.sh
index 5f6732b..2c75e9f 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -453,6 +453,10 @@ then
 		test "$fork_point" = auto && fork_point=t
 		;;
 	*)	upstream_name="$1"
+		if test "$upstream_name" = "-"
+		then
+			upstream_name="@{-1}"
+		fi
 		shift
 		;;
 	esac
diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index 6d94b1f..6176754 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -88,6 +88,17 @@ test_expect_success 'rebase from ambiguous branch name' '
 	git rebase master
 '
 
+test_expect_success 'rebase using shorthand' '
+	git checkout master &&
+	git checkout -b shorthand HEAD^ &&
+	git rebase - 1>shorthand.stdout &&
+	git checkout master &&
+	git branch -D shorthand &&
+	git checkout -b shorthand HEAD^ &&
+	git rebase @{-1} 1>without_shorthand.stdout &&
+	test_i18ncmp without_shorthand.stdout shorthand.stdout
+'
+
 test_expect_success 'rebase a single mode change' '
 	git checkout master &&
 	git branch -D topic &&
-- 
1.8.5.2 (Apple Git-48)
Junio C Hamano· Mar 19, 2014, 17:53 UTC · re: Brian Gesiak · lore

Re: [PATCH v2] git-rebase: Teach rebase "-" shorthand.

Brian Gesiak <modocache@gmail.com> writes:
Show 18 quoted lines
> diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
> index 6d94b1f..6176754 100755
> --- a/t/t3400-rebase.sh
> +++ b/t/t3400-rebase.sh
> @@ -88,6 +88,17 @@ test_expect_success 'rebase from ambiguous branch name' '
>  	git rebase master
>  '
>  
> +test_expect_success 'rebase using shorthand' '
> +	git checkout master &&
> +	git checkout -b shorthand HEAD^ &&
> +	git rebase - 1>shorthand.stdout &&
> +	git checkout master &&
> +	git branch -D shorthand &&
> +	git checkout -b shorthand HEAD^ &&
> +	git rebase @{-1} 1>without_shorthand.stdout &&
> +	test_i18ncmp without_shorthand.stdout shorthand.stdout
> +'
A handful of issues here:
 * "1>target" looks unconventional and wastes readers' time, forcing
   them to wonder if there is anything special going on, only to
   realize there isn't anything noteworthy.  Saying ">target" like
   everybody else does avoids attracting unnecessary attention.
 * "rebase using shorthand" is somewhat a myopic title; it assumes
   that the only short-hand relevant to rebase will be that a "-"
   stands for "@{-1}" to specify the branch we rebase the current
   branch off of.
 * The usual filename for the output from the command being tested
   is 'actual', and the usual filename for the expected output is
   'expect'.  In this case, you are verifying that the output from
   "rebase -" is the same as the output from "rebase @{-1}", so it
   is more conventional to call the former 'actual' and the latter
   'expect'.
 * Is the eye-candy output to the standard output what is the most
   interesting during the execution of a rebase?  Wouldn't we be
   more interested to make sure that we did transplant the history
   on the same commit between two cases?
   "rebase -" with your change still says something like this:
        First, rewinding head to replay your work on top of it...
        Fast-forwarded HEAD to @{-1}.
   instead of "Fast-forwarded HEAD to -".  Somebody may later want
   to "fix" this, making these two eye-candy output to be different
   from each other, and what your test expects will no longer hold
   (not that I think it is better to say "-" instead of @{-1}
   there).
I'll tentatively queue it with a minor tweak (see below).
Thanks.
-- >8 --
From: Brian Gesiak <modocache@gmail.com>
Date: Wed, 19 Mar 2014 20:02:15 +0900
Subject: [PATCH] rebase: allow "-" short-hand for the previous branch

Teach rebase the same shorthand as checkout and merge to name the branch to rebase the current branch on; that is, that "-" means "the branch we were previously on".

Requested-by: Tim Chase <git@tim.thechases.com>
Signed-off-by: Brian Gesiak <modocache@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 git-rebase.sh     |  4 ++++
 t/t3400-rebase.sh | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)
Show changes to 2 files +21 −0

git-rebase.sh, t/t3400-rebase.sh

diff --git a/git-rebase.sh b/git-rebase.sh
index 8a3efa2..658c003 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -449,6 +449,10 @@ then
 		test "$fork_point" = auto && fork_point=t
 		;;
 	*)	upstream_name="$1"
+		if test "$upstream_name" = "-"
+		then
+			upstream_name="@{-1}"
+		fi
 		shift
 		;;
 	esac
diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index 6d94b1f..80e0a95 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -88,6 +88,23 @@ test_expect_success 'rebase from ambiguous branch name' '
 	git rebase master
 '
 
+test_expect_success 'rebase off of the previous branch using "-"' '
+	git checkout master &&
+	git checkout HEAD^ &&
+	git rebase @{-1} >expect.messages &&
+	git merge-base master HEAD >expect.forkpoint &&
+
+	git checkout master &&
+	git checkout HEAD^ &&
+	git rebase - >actual.messages &&
+	git merge-base master HEAD >actual.forkpoint &&
+
+	test_cmp expect.forkpoint actual.forkpoint &&
+	# the next one is dubious---we may want to say "-",
+	# instead of @{-1}, in the message
+	test_i18ncmp expect.messages actual.messages
+'
+
 test_expect_success 'rebase a single mode change' '
 	git checkout master &&
 	git branch -D topic &&
-- 
1.9.1-423-g4596e3a
John Keeping· Mar 19, 2014, 18:02 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] git-rebase: Teach rebase "-" shorthand.

On Wed, Mar 19, 2014 at 10:53:01AM -0700, Junio C Hamano wrote:
Show 10 quoted lines
>    "rebase -" with your change still says something like this:
> 
>         First, rewinding head to replay your work on top of it...
>         Fast-forwarded HEAD to @{-1}.
> 
>    instead of "Fast-forwarded HEAD to -".  Somebody may later want
>    to "fix" this, making these two eye-candy output to be different
>    from each other, and what your test expects will no longer hold
>    (not that I think it is better to say "-" instead of @{-1}
>    there).

I don't think either of these is correct. When using "-" with the commands that already support it, I have occasionally found that "-" isn't what I thought it was.

Can we use `git name-rev` to put the actual name here, so that people who have not done what they intended can hopefully notice sooner?

Brian Gesiak· Mar 19, 2014, 18:09 UTC · re: John Keeping · lore

Re: [PATCH v2] git-rebase: Teach rebase "-" shorthand.

Thank you for the feedback and tweaks!
> Is the eye-candy output to the standard output what is the most
> interesting during the execution of a rebase?  Wouldn't we be
> more interested to make sure that we did transplant the history
> on the same commit between two cases?
I agree. I'll consult the other tests to see how to write such a test.
> Can we use `git name-rev` to put the actual name here, so that people
> who have not done what they intended can hopefully notice sooner?

This sounds like a great idea! Doing so would mirror how `git checkout` behaves; checkout informs the user of which branch they have switched to when using the "-" shorthand: "Switched to branch 'master'".

Should I submit a new patch, or reroll this one?
- Brian Gesiak
Junio C Hamano· Mar 19, 2014, 19:02 UTC · re: John Keeping · lore

Re: [PATCH v2] git-rebase: Teach rebase "-" shorthand.

John Keeping <john@keeping.me.uk> writes:
Show 18 quoted lines
> On Wed, Mar 19, 2014 at 10:53:01AM -0700, Junio C Hamano wrote:
>>    "rebase -" with your change still says something like this:
>> 
>>         First, rewinding head to replay your work on top of it...
>>         Fast-forwarded HEAD to @{-1}.
>> 
>>    instead of "Fast-forwarded HEAD to -".  Somebody may later want
>>    to "fix" this, making these two eye-candy output to be different
>>    from each other, and what your test expects will no longer hold
>>    (not that I think it is better to say "-" instead of @{-1}
>>    there).
>
> I don't think either of these is correct.  When using "-" with the
> commands that already support it, I have occasionally found that "-"
> isn't what I thought it was.
>
> Can we use `git name-rev` to put the actual name here, so that people
> who have not done what they intended can hopefully notice sooner?

That sounds like a right thing to do. It however is totally orthogonal to the change we are discussing, and should be done as a separate patch.

Thanks.
John Keeping· Mar 19, 2014, 19:12 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] git-rebase: Teach rebase "-" shorthand.

On Wed, Mar 19, 2014 at 12:02:01PM -0700, Junio C Hamano wrote:
Show 24 quoted lines
> John Keeping <john@keeping.me.uk> writes:
> 
> > On Wed, Mar 19, 2014 at 10:53:01AM -0700, Junio C Hamano wrote:
> >>    "rebase -" with your change still says something like this:
> >> 
> >>         First, rewinding head to replay your work on top of it...
> >>         Fast-forwarded HEAD to @{-1}.
> >> 
> >>    instead of "Fast-forwarded HEAD to -".  Somebody may later want
> >>    to "fix" this, making these two eye-candy output to be different
> >>    from each other, and what your test expects will no longer hold
> >>    (not that I think it is better to say "-" instead of @{-1}
> >>    there).
> >
> > I don't think either of these is correct.  When using "-" with the
> > commands that already support it, I have occasionally found that "-"
> > isn't what I thought it was.
> >
> > Can we use `git name-rev` to put the actual name here, so that people
> > who have not done what they intended can hopefully notice sooner?
> 
> That sounds like a right thing to do.  It however is totally
> orthogonal to the change we are discussing, and should be done as a
> separate patch.
Is it not part of adding support for "-"?

I'm not arguing for a change to any existing functionality, just to the behaviour introduced by this patch, which is basically a change from "@{-1}" to "$(git name-rev --name-only @{-1})" in the patch. (The error handling of name-rev appears not to be very useful here when the previous branch has been deleted, so I don't think it's quite that simple, but that's the principle.)

Junio C Hamano· Mar 19, 2014, 19:41 UTC · re: John Keeping · lore

Re: [PATCH v2] git-rebase: Teach rebase "-" shorthand.

John Keeping <john@keeping.me.uk> writes:
Show 27 quoted lines
> On Wed, Mar 19, 2014 at 12:02:01PM -0700, Junio C Hamano wrote:
>> John Keeping <john@keeping.me.uk> writes:
>> 
>> > On Wed, Mar 19, 2014 at 10:53:01AM -0700, Junio C Hamano wrote:
>> >>    "rebase -" with your change still says something like this:
>> >> 
>> >>         First, rewinding head to replay your work on top of it...
>> >>         Fast-forwarded HEAD to @{-1}.
>> >> 
>> >>    instead of "Fast-forwarded HEAD to -".  Somebody may later want
>> >>    to "fix" this, making these two eye-candy output to be different
>> >>    from each other, and what your test expects will no longer hold
>> >>    (not that I think it is better to say "-" instead of @{-1}
>> >>    there).
>> >
>> > I don't think either of these is correct.  When using "-" with the
>> > commands that already support it, I have occasionally found that "-"
>> > isn't what I thought it was.
>> >
>> > Can we use `git name-rev` to put the actual name here, so that people
>> > who have not done what they intended can hopefully notice sooner?
>> 
>> That sounds like a right thing to do.  It however is totally
>> orthogonal to the change we are discussing, and should be done as a
>> separate patch.
>
> Is it not part of adding support for "-"?
I thought your suggestion was:
    'rebase @{-1}' says 'Fast-fowarded HEAD to @{-1}'. It should say
    'Fast-forwarded HEAD to 4f407407 (rebase: allow "-" short-hand
    for the previous branch, 2014-03-19)' instead.
Or it could be:
    'rebase @{-1}' says 'Fast-fowarded HEAD to @{-1}'. It should say
    'Fast-forwarded HEAD to master' instead.

In either case, it does not look like such a change is about teaching "-" as a synonym to "@{-1}".

John Keeping· Mar 19, 2014, 19:55 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] git-rebase: Teach rebase "-" shorthand.

On Wed, Mar 19, 2014 at 12:41:31PM -0700, Junio C Hamano wrote:
Show 43 quoted lines
> John Keeping <john@keeping.me.uk> writes:
> 
> > On Wed, Mar 19, 2014 at 12:02:01PM -0700, Junio C Hamano wrote:
> >> John Keeping <john@keeping.me.uk> writes:
> >> 
> >> > On Wed, Mar 19, 2014 at 10:53:01AM -0700, Junio C Hamano wrote:
> >> >>    "rebase -" with your change still says something like this:
> >> >> 
> >> >>         First, rewinding head to replay your work on top of it...
> >> >>         Fast-forwarded HEAD to @{-1}.
> >> >> 
> >> >>    instead of "Fast-forwarded HEAD to -".  Somebody may later want
> >> >>    to "fix" this, making these two eye-candy output to be different
> >> >>    from each other, and what your test expects will no longer hold
> >> >>    (not that I think it is better to say "-" instead of @{-1}
> >> >>    there).
> >> >
> >> > I don't think either of these is correct.  When using "-" with the
> >> > commands that already support it, I have occasionally found that "-"
> >> > isn't what I thought it was.
> >> >
> >> > Can we use `git name-rev` to put the actual name here, so that people
> >> > who have not done what they intended can hopefully notice sooner?
> >> 
> >> That sounds like a right thing to do.  It however is totally
> >> orthogonal to the change we are discussing, and should be done as a
> >> separate patch.
> >
> > Is it not part of adding support for "-"?
> 
> I thought your suggestion was:
> 
>     'rebase @{-1}' says 'Fast-fowarded HEAD to @{-1}'. It should say
>     'Fast-forwarded HEAD to 4f407407 (rebase: allow "-" short-hand
>     for the previous branch, 2014-03-19)' instead.
> 
> Or it could be:
> 
>     'rebase @{-1}' says 'Fast-fowarded HEAD to @{-1}'. It should say
>     'Fast-forwarded HEAD to master' instead.
> 
> In either case, it does not look like such a change is about
> teaching "-" as a synonym to "@{-1}".
My suggestion was specifically:
    'rebase -' says 'Fast-forwarded HEAD to -'.  It should say
    'Fast-forwarded HEAD to master' instead.

I'm not sure it's desirable to attempt to canonicalise whatever the user writes on the command line, but since we're special-casing '-' I think it is a good thing to print the branch name in that case.

Junio C Hamano· Mar 19, 2014, 21:02 UTC · re: John Keeping · lore

Re: [PATCH v2] git-rebase: Teach rebase "-" shorthand.

John Keeping <john@keeping.me.uk> writes:
Show 18 quoted lines
>> I thought your suggestion was:
>> 
>>     'rebase @{-1}' says 'Fast-fowarded HEAD to @{-1}'. It should say
>>     'Fast-forwarded HEAD to 4f407407 (rebase: allow "-" short-hand
>>     for the previous branch, 2014-03-19)' instead.
>> 
>> Or it could be:
>> 
>>     'rebase @{-1}' says 'Fast-fowarded HEAD to @{-1}'. It should say
>>     'Fast-forwarded HEAD to master' instead.
>> 
>> In either case, it does not look like such a change is about
>> teaching "-" as a synonym to "@{-1}".
>
> My suggestion was specifically:
>
>     'rebase -' says 'Fast-forwarded HEAD to -'.  It should say
>     'Fast-forwarded HEAD to master' instead.
OK, it was closer to the latter.

But why is it OK to leave @{-1}, which is just as "hmm, I do not remember what the previous branch was myself" when the user says "@{-1}" in the output while it not OK to leave "-" in the output?

I do not think of any sane reason, and that is why I think this improvement is not part of "teaching rebase that '-' can be used in place of @{-1}" topic.

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