[PATCH] merge: allow "-" as a short-hand for "previous branch"

[PATCH] merge: allow "-" as a short-hand for "previous branch"

[Junio C Hamano]

Just like "git checkout -" is a short-hand for "git checkout @{-1}" to
conveniently switch back to the previous branch, "git merge -" is a
short-hand for "git merge @{-1}" to conveniently merge the previous branch.

It will allow me to say:

    $ git checkout -b au/topic
    $ git am -s ./+au-topic.mbox
    $ git checkout pu
    $ git merge -

which is an extremely typical and repetitive operation during my git day.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/merge.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index d54e7dd..0bdd19a 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1062,9 +1062,12 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	if (!allow_fast_forward && fast_forward_only)
 		die(_("You cannot combine --no-ff with --ff-only."));
 
-	if (!argc && !abort_current_merge && default_to_upstream)
-		argc = setup_with_upstream(&argv);
-
+	if (!abort_current_merge) {
+		if (!argc && default_to_upstream)
+			argc = setup_with_upstream(&argv);
+		else if (argc == 1 && !strcmp(argv[0], "-"))
+			argv[0] = "@{-1}";
+	}
 	if (!argc)
 		usage_with_options(builtin_merge_usage,
 			builtin_merge_options);
-- 
1.7.5.rc1

Re: [PATCH] merge: allow "-" as a short-hand for "previous branch"

[Thomas Adam]

Hi,

On 8 April 2011 00:03, Junio C Hamano <gitster@pobox.com> wrote:
> Just like "git checkout -" is a short-hand for "git checkout @{-1}" to
> conveniently switch back to the previous branch, "git merge -" is a
> short-hand for "git merge @{-1}" to conveniently merge the previous branch.
>
> It will allow me to say:
>
>    $ git checkout -b au/topic
>    $ git am -s ./+au-topic.mbox
>    $ git checkout pu
>    $ git merge -

I agree this is is useful, but is there a danger of this being a
common typo, and people merging in previous branches a lot more often
than they ever intended?  In the case of "git checkout -" that's not
as fatal, but if I ever mistype "git merge -" -- I'm now left with an
unraveling exercise to do.

Hopefully it won't be an issue, as it's no worse than mistyping branch
names -- I suppose it's the sheer length of "-" in this case which
leads to more potential for problems.

-- Thomas Adam

Re: [PATCH] merge: allow "-" as a short-hand for "previous branch"

[Junio C Hamano]

Thomas Adam <thomas@xteddy.org> writes:

> I agree this is is useful, but is there a danger of this being a
> common typo, and people merging in previous branches a lot more often
> than they ever intended?  In the case of "git checkout -" that's not
> as fatal, but if I ever mistype "git merge -" -- I'm now left with an
> unraveling exercise to do.

Just like you can checkout the previous branch back if you found you
checked out a wrong branch by a typo, if you found that you merged a wrong
branch, you can just reset it away back to ORIG_HEAD, no?

Or am I missing something more obvious?

Re: [PATCH] merge: allow "-" as a short-hand for "previous branch"

[Michael J Gruber]

Junio C Hamano venit, vidit, dixit 08.04.2011 01:26:
> Thomas Adam <thomas@xteddy.org> writes:
> 
>> I agree this is is useful, but is there a danger of this being a
>> common typo, and people merging in previous branches a lot more often
>> than they ever intended?  In the case of "git checkout -" that's not
>> as fatal, but if I ever mistype "git merge -" -- I'm now left with an
>> unraveling exercise to do.
> 
> Just like you can checkout the previous branch back if you found you
> checked out a wrong branch by a typo, if you found that you merged a wrong
> branch, you can just reset it away back to ORIG_HEAD, no?
> 
> Or am I missing something more obvious?

Only tests and doc :)

Seriously, I like that. If there are more places where this makes sense
(I haven't looked) we might even factor it out. In principle it makes
sense everywhere where a branch name makes sense, e.g.:

git branch -D foo
#...can't delete the current branch
git checkout whatever
git branch -D -

In this case, shell history is faster, of course.

Michael

Re: [PATCH] merge: allow "-" as a short-hand for "previous branch"

[Junio C Hamano]

Michael J Gruber <git@drmicha.warpmail.net> writes:

> ... In principle it makes
> sense everywhere where a branch name makes sense, e.g.:
>
> git branch -D foo
> #...can't delete the current branch
> git checkout whatever
> git branch -D -
>
> In this case, shell history is faster, of course.

Yeah, and "branch -[dD]" is truly destructive, so...