[PATCH v2 2/2] branch: support for shortcuts like @{-1} completed

["Rubén Justo" <rjusto@gmail.com>]

branch command with options "edit-description", "set-upstream-to"
and "unset-upstream" expects a branch name.  Since ae5a6c3684
(checkout: implement "@{-N}" shortcut name for N-th last branch,
2009-01-17) a branch can be specified using shortcuts like @{-1}.
Those shortcuts need to be resolved when considering the
arguments.

Usage examples:

We can modify the description of the previously checked out branch
with:

$ git branch --edit--description @{-1}

We can modify the upstream of the previously checked out branch
with:

$ git branch --set-upstream-to upstream @{-1}
$ git branch --unset-upstream @{-1}

Signed-off-by: Rubén Justo <rjusto@gmail.com>
---
 builtin/branch.c                      | 29 +++++++++++++++++++++------
 t/t3204-branch-name-interpretation.sh | 25 +++++++++++++++++++++++
 2 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/builtin/branch.c b/builtin/branch.c
index 5229cb796f..6ee95b4179 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -791,14 +791,17 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 	} else if (edit_description) {
 		const char *branch_name;
 		struct strbuf branch_ref = STRBUF_INIT;
+		struct strbuf buf = STRBUF_INIT;
 		int ret = 0;
 
 		if (!argc) {
 			if (filter.detached)
 				die(_("Cannot give description to detached HEAD"));
 			branch_name = head;
-		} else if (argc == 1)
-			branch_name = argv[0];
+		} else if (argc == 1) {
+			strbuf_branchname(&buf, argv[0], INTERPRET_BRANCH_LOCAL);
+			branch_name = buf.buf;
+		}
 		else
 			die(_("cannot edit description of more than one branch"));
 
@@ -814,6 +817,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 			ret = edit_branch_description(branch_name);
 
 		strbuf_release(&branch_ref);
+		strbuf_release(&buf);
 		return ret;
 	} else if (copy) {
 		if (!argc)
@@ -834,9 +838,15 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		else
 			die(_("too many arguments for a rename operation"));
 	} else if (new_upstream) {
-		struct branch *branch = branch_get(argv[0]);
+		struct branch *branch;
+		struct strbuf buf = STRBUF_INIT;
 
-		if (argc > 1)
+		if (!argc)
+			branch = branch_get(NULL);
+		else if (argc == 1) {
+			strbuf_branchname(&buf, argv[0], INTERPRET_BRANCH_LOCAL);
+			branch = branch_get(buf.buf);
+		} else
 			die(_("too many arguments to set new upstream"));
 
 		if (!branch) {
@@ -853,11 +863,17 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		dwim_and_setup_tracking(the_repository, branch->name,
 					new_upstream, BRANCH_TRACK_OVERRIDE,
 					quiet);
+		strbuf_release(&buf);
 	} else if (unset_upstream) {
-		struct branch *branch = branch_get(argv[0]);
+		struct branch *branch;
 		struct strbuf buf = STRBUF_INIT;
 
-		if (argc > 1)
+		if (!argc)
+			branch = branch_get(NULL);
+		else if (argc == 1) {
+			strbuf_branchname(&buf, argv[0], INTERPRET_BRANCH_LOCAL);
+			branch = branch_get(buf.buf);
+		} else
 			die(_("too many arguments to unset upstream"));
 
 		if (!branch) {
@@ -870,6 +886,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		if (!branch_has_merge_config(branch))
 			die(_("Branch '%s' has no upstream information"), branch->name);
 
+		strbuf_reset(&buf);
 		strbuf_addf(&buf, "branch.%s.remote", branch->name);
 		git_config_set_multivar(buf.buf, NULL, NULL, CONFIG_FLAGS_MULTI_REPLACE);
 		strbuf_reset(&buf);
diff --git a/t/t3204-branch-name-interpretation.sh b/t/t3204-branch-name-interpretation.sh
index 993a6b5eff..0a423298d6 100755
--- a/t/t3204-branch-name-interpretation.sh
+++ b/t/t3204-branch-name-interpretation.sh
@@ -133,4 +133,29 @@ test_expect_success 'checkout does not treat remote @{upstream} as a branch' '
 	expect_branch HEAD one
 '
 
+test_expect_success 'edit-description via @{-1}' '
+	git checkout main &&
+	git checkout - &&
+	write_script editor <<-\EOF &&
+		echo "Branch description" >"$1"
+	EOF
+	EDITOR=./editor git branch --edit-description @{-1} &&
+		write_script editor <<-\EOF &&
+		git stripspace -s <"$1" >"EDITOR_OUTPUT"
+	EOF
+	EDITOR=./editor git branch --edit-description @{-1} &&
+	echo "Branch description" >expect &&
+	test_cmp expect EDITOR_OUTPUT
+'
+
+test_expect_success 'modify branch upstream via "@{-1}" and "@{-1}@{upstream}"' '
+	git branch upstream-branch &&
+	git checkout -b upstream-other -t upstream-branch &&
+	git checkout - &&
+	git branch --set-upstream-to @{-1} @{-1}@{upstream} &&
+	test "$(git config branch.upstream-branch.merge)" = "refs/heads/upstream-other" &&
+	git branch --unset-upstream @{-1} &&
+	test_must_fail git config branch.upstream-other.merge
+'
+
 test_done
-- 
2.36.1