Re: [PATCH v5 2/2] branch: add flags and config to inherit tracking

It can be helpful when creating a new branch to use the existing
tracking configuration from the branch point. However, there is
currently not a method to automatically do so.

Teach git-{branch,checkout,switch} an "inherit" argument to the
"--track" option. When this is set, creating a new branch will cause the
tracking configuration to default to the configuration of the branch
point, if set.

For example, if branch "main" tracks "origin/main", and we run
`git checkout --track=inherit -b feature main`, then branch "feature"
will track "origin/main". Thus, `git status` will show us how far
ahead/behind we are from origin, and `git pull` will pull from origin.

This is particularly useful when creating branches across many
submodules, such as with `git submodule foreach ...` (or if running with
a patch such as [1], which we use at $job), as it avoids having to
manually set tracking info for each submodule.

Since we've added an argument to "--track", also add "--track=direct" as
another way to explicitly get the original "--track" behavior ("--track"
without an argument still works as well).

@@ -10,7 +10,8 @@ enum branch_track {
 	BRANCH_TRACK_REMOTE,
 	BRANCH_TRACK_ALWAYS,
 	BRANCH_TRACK_EXPLICIT,
-	BRANCH_TRACK_OVERRIDE
+	BRANCH_TRACK_OVERRIDE,
+	BRANCH_TRACK_INHERIT
 };

 
 extern enum branch_track git_branch_track;

diff --git a/builtin/branch.c b/builtin/branch.c
index b23b1d1752..ebde5023c3 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c

@@ -632,8 +632,10 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		OPT__VERBOSE(&filter.verbose,
 			N_("show hash and subject, give twice for upstream branch")),
 		OPT__QUIET(&quiet, N_("suppress informational messages")),
-		OPT_SET_INT('t', "track",  &track, N_("set up tracking mode (see git-pull(1))"),
-			BRANCH_TRACK_EXPLICIT),
+		OPT_CALLBACK_F('t', "track",  &track, "direct|inherit",
+			N_("set branch tracking configuration"),
+			PARSE_OPT_OPTARG | PARSE_OPT_LITERAL_ARGHELP,
+			parse_opt_tracking_mode),
 		OPT_SET_INT_F(0, "set-upstream", &track, N_("do not use"),
 			BRANCH_TRACK_OVERRIDE, PARSE_OPT_HIDDEN),

 		OPT_STRING('u', "set-upstream-to", &new_upstream, N_("upstream"), N_("change the upstream info")),

diff --git a/builtin/checkout.c b/builtin/checkout.c
index b5d477919a..45dab414ea 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c

@@ -1532,8 +1532,10 @@ static struct option *add_common_switch_branch_options(
 {
 	struct option options[] = {
 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
-		OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
-			BRANCH_TRACK_EXPLICIT),
+		OPT_CALLBACK_F('t', "track",  &opts->track, "direct|inherit",
+			N_("set up tracking mode (see git-pull(1))"),
+			PARSE_OPT_OPTARG | PARSE_OPT_LITERAL_ARGHELP,
+			parse_opt_tracking_mode),
 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
 			   PARSE_OPT_NOCOMPLETE),
 		OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),