[RFC PATCH 1/1] push: make '-u' have default arguments

[Abhradeep Chakraborty <chakrabortyabhradeep79@gmail.com>]

For now, -u in 'push' command requires two arguments (<repository>
and <refspec>) to successfully track upstream branch. In most cases,
users want to set an upstream branch for the local branch they are
currently on and the short names of these two branches are same in
most of the cases. There are plenty of configurations to set default
branches for push but again users can't run argumentless pull, rebase
etc. So it will be good to have '-u' having default arguments.

This commit gives ability to '-u' to have default arguments. 'git push
-u' runs normally if <repository> and <refspec> are given. But
if those are not given then it tries to get the value of <repository>
from 'branch.<current_branch>.remote'. If not found, it sets 'origin'
as the value of <repository>. <refspec> would be the current branch's
short name.

However 'git push -u --all' work normally as before.

Signed-off-by: Abhradeep Chakraborty <chakrabortyabhradeep79@gmail.com>
---
 Documentation/git-push.txt |  6 +++++
 builtin/push.c             | 48 ++++++++++++++++++++++++++++----------
 t/t5523-push-upstream.sh   | 11 +++++++++
 3 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/Documentation/git-push.txt b/Documentation/git-push.txt
index 2f25aa3a29..e1a8b41818 100644
--- a/Documentation/git-push.txt
+++ b/Documentation/git-push.txt
@@ -375,6 +375,12 @@ Specifying `--no-force-if-includes` disables this behavior.
 	upstream (tracking) reference, used by argument-less
 	linkgit:git-pull[1] and other commands. For more information,
 	see `branch.<name>.merge` in linkgit:git-config[1].
++
+If you use -u without any arguments (i.e. no <repository> and <refspec>),
+it will first try to get the <repository> from current branch's remote
+configuration (i.e. from `branch.<name>.remote`). If not found, it will set
+`origin` as the value of <repository> and <refspec> will be the current
+branch's refspec.
 
 --[no-]thin::
 	These options are passed to linkgit:git-send-pack[1]. A thin transfer
diff --git a/builtin/push.c b/builtin/push.c
index 4b026ce6c6..2e417a06ad 100644
--- a/builtin/push.c
+++ b/builtin/push.c
@@ -527,6 +527,25 @@ static int git_push_config(const char *k, const char *v, void *cb)
 	return git_default_config(k, v, NULL);
 }
 
+static struct remote *pushremote_get_remote(const char *repo)
+{
+	struct remote *remote = pushremote_get(repo);
+	if (!remote) {
+		if (repo)
+			die(_("bad repository '%s'"), repo);
+		die(_("No configured push destination.\n"
+		    "Either specify the URL from the command-line or configure a remote repository using\n"
+		    "\n"
+		    "    git remote add <name> <url>\n"
+		    "\n"
+		    "and then push using the remote name\n"
+		    "\n"
+		    "    git push <name>\n"));
+	}
+
+	return remote;
+}
+
 int cmd_push(int argc, const char **argv, const char *prefix)
 {
 	int flags = 0;
@@ -537,6 +556,7 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 	struct string_list push_options_cmdline = STRING_LIST_INIT_DUP;
 	struct string_list *push_options;
 	const struct string_list_item *item;
+	struct remote *default_remote = NULL;
 	struct remote *remote;
 
 	struct option options[] = {
@@ -603,23 +623,27 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 	if (tags)
 		refspec_append(&rs, "refs/tags/*");
 
+	if ((argc == 0) && (flags & TRANSPORT_PUSH_SET_UPSTREAM) && !(flags & TRANSPORT_PUSH_ALL)) {
+		struct branch *branch = branch_get(NULL);
+		if (branch) {
+			argc += 2;
+			default_remote = pushremote_get_remote(repo);
+			argv[0] = default_remote->name;
+			argv[1] = branch->name;
+		}
+	}
+
 	if (argc > 0) {
 		repo = argv[0];
 		set_refspecs(argv + 1, argc - 1, repo);
 	}
 
-	remote = pushremote_get(repo);
-	if (!remote) {
-		if (repo)
-			die(_("bad repository '%s'"), repo);
-		die(_("No configured push destination.\n"
-		    "Either specify the URL from the command-line or configure a remote repository using\n"
-		    "\n"
-		    "    git remote add <name> <url>\n"
-		    "\n"
-		    "and then push using the remote name\n"
-		    "\n"
-		    "    git push <name>\n"));
+	if (default_remote) {
+		remote = default_remote;
+		default_remote = NULL;
+	}
+	else {
+		remote = pushremote_get_remote(repo);
 	}
 
 	if (remote->mirror)
diff --git a/t/t5523-push-upstream.sh b/t/t5523-push-upstream.sh
index fdb4292056..69970b6263 100755
--- a/t/t5523-push-upstream.sh
+++ b/t/t5523-push-upstream.sh
@@ -60,6 +60,17 @@ test_expect_success 'push -u :topic_2' '
 	check_config topic_2 upstream refs/heads/other2
 '
 
+test_expect_success 'push -u' '
+	git push -u &&
+	check_config main upstream refs/heads/main
+'
+
+test_expect_success 'push -u --dry-run' '
+	git push -u upstream main:other &&
+	git push -u --dry-run &&
+	check_config main upstream refs/heads/other
+'
+
 test_expect_success 'push -u --all' '
 	git branch all1 &&
 	git branch all2 &&
-- 
2.17.1