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

["Rubén Justo" <rjusto@gmail.com>]

Hi Johannes,

On 8/16/22 11:31 AM, Johannes Schindelin wrote:

>> $ git merge - old-branch
>> merge: - - not something we can merge
> 
> This is confusing me: how is the patch supporting `git branch -d -`
> aligned with the presented `git merge` invocations?

"merge" supports multiple objects to be specified, but "-" only is 
accepted if just one argument is specified, as Junio did it in:

commit 4e8115fff135a09f75020083f51722e7e35eb6e9
Author: Junio C Hamano <gitster@pobox.com>
Date:   Thu Apr 7 15:57:57 2011 -0700

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

     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>

diff --git a/builtin/merge.c b/builtin/merge.c
index d54e7ddbb1..0bdd19a137 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);



So I aligned "branch -d" (or "delete-branch") with that.

The other two commands that already support "-", also works the same way:

$ git checkout -B - default
fatal: '-' is not a valid branch name

$ git rebase default -
fatal: no such branch/commit '-'

To summarize, my goal is to allow:

$ git checkout work_to_review
$ git checkout -
$ git merge - # or git rebase -
$ git branch -d -

Makes sense to me...

I've updated the commit message with a more specific message and removed 
the braces, jic.