Re: [PATCH] branch: allow "-" as a short-hand for "previous branch"
Hi Junio & Rubén,
On Tue, 16 Aug 2022, Johannes Schindelin wrote:
Show 33 quoted lines
> On Mon, 8 Aug 2022, Junio C Hamano wrote:
>
> > Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> >
> > > @@ -1420,6 +1420,12 @@ static int interpret_nth_prior_checkout(struct repository *r,
> > > const char *brace;
> > > char *num_end;
> > >
> > > + if (namelen == 1 && *name == '-') {
> > > + brace = name;
> > > + nth = 1;
> > > + goto find_nth_checkout;
> > > + }
> > > +
> > > if (namelen < 4)
> > > return -1;
> > > if (name[0] != '@' || name[1] != '{' || name[2] != '-')
> >
> > If a solution along this line works, it would be far cleaner design
> > than the various hacks we have done in the past, noticing "-" and
> > replacing with "@{-1}".
>
> Indeed, but it does not work as-is: `interpret_nth_prior_checkout()` is
> used on prefixes of a rev, and for the special handling of `-` we cannot
> have that.
>
> [...]
>
> One thing we could do, however, would be to patch only
> `repo_interpret_branch_name()`, i.e. only allow `-` to imply the
> previous branch name in invocations where a branch name is asked for
> _explicitly_. I.e. not any random revision, but specifically a branch
> name.This patch does that:
-- snip --
diff --git a/object-name.c b/object-name.c
index 4d2746574cd..a2732be3b71 100644
--- a/object-name.c
+++ b/object-name.c
@@ -1616,6 +1616,20 @@ int repo_interpret_branch_name(struct repository *r,
if (!namelen)
namelen = strlen(name);
+ if (namelen == 1 && *name == '-') {
+ struct grab_nth_branch_switch_cbdata cb = {
+ .remaining = 1,
+ .sb = buf
+ };
+
+ if (refs_for_each_reflog_ent_reverse(get_main_ref_store(r),
+ "HEAD",
+ grab_nth_branch_switch,
+ &cb) <= 0)
+ return -1;
+ return namelen;
+ }
+
if (!options->allowed || (options->allowed & INTERPRET_BRANCH_LOCAL)) {
len = interpret_nth_prior_checkout(r, name, namelen, buf);
if (!len) {
diff --git a/t/t3204-branch-name-interpretation.sh b/t/t3204-branch-name-interpretation.sh
index 993a6b5eff7..5acbef95913 100755
--- a/t/t3204-branch-name-interpretation.sh
+++ b/t/t3204-branch-name-interpretation.sh
@@ -67,6 +67,22 @@ test_expect_success 'delete branch via @{-1}' '
expect_deleted previous-del
'
+test_expect_success 'delete branch via -' '
+ git checkout -b previous-del &&
+ git checkout - &&
+
+ git branch -d - &&
+ expect_deleted previous-del &&
+
+ git branch previous-del2 &&
+ git checkout -b previous-del &&
+ git checkout - &&
+
+ git branch -d previous-del2 - &&
+ expect_deleted previous-del &&
+ expect_deleted previous-del2
+'
+
test_expect_success 'delete branch via local @{upstream}' '
git branch local-del &&
git branch --set-upstream-to=local-del &&
-- snap --
This adds support for things like `git branch -d -`, and it even verifies
that that works.
What does not work with this patch is `git show -`. I am not sure whether
we want to make that work, although I have to admit that I would use it.
Often. And this patch would make it work, the test suite even passes with
it:
-- snip --
diff --git a/revision.c b/revision.c
index f4eee11cc8b..207b554aef1 100644
--- a/revision.c
+++ b/revision.c
@@ -2802,7 +2802,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
revarg_opt |= REVARG_CANNOT_BE_FILENAME;
for (left = i = 1; i < argc; i++) {
const char *arg = argv[i];
- if (!seen_end_of_options && *arg == '-') {
+ if (!seen_end_of_options && *arg == '-' && arg[1]) {
int opts;
opts = handle_revision_pseudo_opt(
-- snap --
That latter patch obviously needs at least one accompanying test case, and
the patch series would then need to drop the special-casings we already
have for "-".
Rubén, do you want to take this a bit further?
Ciao,
Dscho
P.S.: For convenient fetching, I opened a draft PR here:
https://github.com/gitgitgadget/git/pull/1329
Johannes Schindelin <johannes.schindelin@gmx.de>