[PATCH] usage: clarify --recurse-submodules as a boolean

[Emily Shaffer <nasamuffin@google.com>]

`git switch` `git checkout`, `git reset`, and `git read-tree` allow a user to choose to
recurse into submodules. All three of these commands' short usage seems
to indicate that `--recurse-submodules` should take an argument. In
practice, though, all three of these commands parse through the same
callback path:

  option_parse_recurse_submodules_worktree_updater(...) checks for
  set/unset, or passes off to...
  parse_update_recurse_submodules_arg(...), which is a straight handoff
  to...
  parse_update_recurse(...), which only accepts true or false.

So ultimately, it can only be true or false, unlike `git push
--recurse-submodules=<enum>`. A user could provide
`--recurse-submodules=true`, but we don't typically suggest that for
boolean arguments.
(Documentation/git-(switch|checkout|reset|read-tree).txt suggests
--[no-]recurse-submodules, too.)

In fact, these three commands are the only ones that use this codepath -
so there's not any reason for it to be so meandering.  It's not possible
to stop using these as a callback entirely, though, because
option_parse_recurse_submodules_worktree_updater() modifies global state
in submodule.c.

Clarify the usage so these commands don't pretend to accept a string
argument. Also, simplify
option_parse_recurse_submodules_worktree_updater() and remove the
now-unused parse_update_recurse_submodules_arg() and
parse_update_recurse() calls.

Signed-off-by: Emily Shaffer <nasamuffin@google.com>

---
 builtin/checkout.c  |  6 +++---
 builtin/read-tree.c |  6 +++---
 builtin/reset.c     |  4 ++--
 submodule-config.c  | 20 --------------------
 submodule-config.h  |  1 -
 submodule.c         |  4 ----
 6 files changed, 8 insertions(+), 33 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 38a8cd6a96..b80ad37fc1 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1587,9 +1587,9 @@ static struct option *add_common_options(struct checkout_opts *opts,
 {
 	struct option options[] = {
 		OPT__QUIET(&opts->quiet, N_("suppress progress reporting")),
-		OPT_CALLBACK_F(0, "recurse-submodules", NULL,
-			    "checkout", "control recursive updating of submodules",
-			    PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater),
+		OPT_CALLBACK_F(0, "recurse-submodules", NULL, NULL,
+			    "control recursive updating of submodules",
+			    PARSE_OPT_NOARG, option_parse_recurse_submodules_worktree_updater),
 		OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
 		OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
 		OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index 600d4f748f..2afb0b24a2 100644
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -149,9 +149,9 @@ int cmd_read_tree(int argc, const char **argv, const char *cmd_prefix)
 			 N_("skip applying sparse checkout filter")),
 		OPT_BOOL(0, "debug-unpack", &opts.internal.debug_unpack,
 			 N_("debug unpack-trees")),
-		OPT_CALLBACK_F(0, "recurse-submodules", NULL,
-			    "checkout", "control recursive updating of submodules",
-			    PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater),
+		OPT_CALLBACK_F(0, "recurse-submodules", NULL, NULL,
+			    "control recursive updating of submodules",
+			    PARSE_OPT_NOARG, option_parse_recurse_submodules_worktree_updater),
 		OPT__QUIET(&opts.quiet, N_("suppress feedback messages")),
 		OPT_END()
 	};
diff --git a/builtin/reset.c b/builtin/reset.c
index 0ed329236c..cdf6ea6df9 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -340,8 +340,8 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 		OPT_SET_INT(0, "keep", &reset_type,
 				N_("reset HEAD but keep local changes"), KEEP),
 		OPT_CALLBACK_F(0, "recurse-submodules", NULL,
-			    "reset", "control recursive updating of submodules",
-			    PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater),
+			    NULL, "control recursive updating of submodules",
+			    PARSE_OPT_NOARG, option_parse_recurse_submodules_worktree_updater),
 		OPT_BOOL('p', "patch", &patch_mode, N_("select hunks interactively")),
 		OPT_BOOL('N', "intent-to-add", &intent_to_add,
 				N_("record only the fact that removed paths will be added later")),
diff --git a/submodule-config.c b/submodule-config.c
index ecf0fcf007..9ef0bdc207 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -338,26 +338,6 @@ int option_fetch_parse_recurse_submodules(const struct option *opt,
 	return 0;
 }
 
-static int parse_update_recurse(const char *opt, const char *arg,
-				int die_on_error)
-{
-	switch (git_parse_maybe_bool(arg)) {
-	case 1:
-		return RECURSE_SUBMODULES_ON;
-	case 0:
-		return RECURSE_SUBMODULES_OFF;
-	default:
-		if (die_on_error)
-			die("bad %s argument: %s", opt, arg);
-		return RECURSE_SUBMODULES_ERROR;
-	}
-}
-
-int parse_update_recurse_submodules_arg(const char *opt, const char *arg)
-{
-	return parse_update_recurse(opt, arg, 1);
-}
-
 static int parse_push_recurse(const char *opt, const char *arg,
 			       int die_on_error)
 {
diff --git a/submodule-config.h b/submodule-config.h
index c2045875bb..fda6ad0162 100644
--- a/submodule-config.h
+++ b/submodule-config.h
@@ -55,7 +55,6 @@ int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg);
 struct option;
 int option_fetch_parse_recurse_submodules(const struct option *opt,
 					  const char *arg, int unset);
-int parse_update_recurse_submodules_arg(const char *opt, const char *arg);
 int parse_push_recurse_submodules_arg(const char *opt, const char *arg);
 void repo_read_gitmodules(struct repository *repo, int skip_if_read);
 void gitmodules_config_oid(const struct object_id *commit_oid);
diff --git a/submodule.c b/submodule.c
index 94644fac0a..fe456c24c9 100644
--- a/submodule.c
+++ b/submodule.c
@@ -236,10 +236,6 @@ int option_parse_recurse_submodules_worktree_updater(const struct option *opt,
 		config_update_recurse_submodules = RECURSE_SUBMODULES_OFF;
 		return 0;
 	}
-	if (arg)
-		config_update_recurse_submodules =
-			parse_update_recurse_submodules_arg(opt->long_name,
-							    arg);
 	else
 		config_update_recurse_submodules = RECURSE_SUBMODULES_ON;
 
-- 
2.40.0.577.gac1e443424-goog