Introduce 'submodule.recurse' option for worktree manipulators

Any command that understands '--recurse-submodules' can have its
default changed to true, by setting the new 'submodule.recurse'
option.

This patch includes read-tree/checkout/reset for working tree
manipulating commands. Later patches will cover other commands.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -3065,6 +3065,11 @@ submodule.active::
 	submodule's path to determine if the submodule is of interest to git
 	commands.
 
+submodule.recurse::
+	Specifies if commands recurse into submodules by default. This
+	applies to all commands that have a `--recurse-submodules` option.
+	Defaults to false.
+
 submodule.fetchJobs::
 	Specifies how many submodules are fetched/cloned at the same time.
 	A positive integer allows up to that number of submodules fetched

builtin/checkout.c

@@ -855,7 +855,7 @@ static int git_checkout_config(const char *var, const char *value, void *cb)
 	}
 
 	if (starts_with(var, "submodule."))
-		return parse_submodule_config_option(var, value);
+		return submodule_config(var, value, NULL);
 
 	return git_xmerge_config(var, value, NULL);
 }

builtin/read-tree.c

@@ -98,6 +98,14 @@ static int debug_merge(const struct cache_entry * const *stages,
 	return 0;
 }
 
+static int git_read_tree_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "submodule.recurse"))
+		return git_default_submodule_config(var, value, cb);
+
+	return git_default_config(var, value, cb);
+}
+
 static struct lock_file lock_file;
 
 int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
@@ -150,7 +158,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 	opts.src_index = &the_index;
 	opts.dst_index = &the_index;
 
-	git_config(git_default_config, NULL);
+	git_config(git_read_tree_config, NULL);
 
 	argc = parse_options(argc, argv, unused_prefix, read_tree_options,
 			     read_tree_usage, 0);

builtin/reset.c

@@ -266,6 +266,14 @@ static int reset_refs(const char *rev, const struct object_id *oid)
 	return update_ref_status;
 }
 
+static int git_reset_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "submodule.recurse"))
+		return git_default_submodule_config(var, value, cb);
+
+	return git_default_config(var, value, cb);
+}
+
 int cmd_reset(int argc, const char **argv, const char *prefix)
 {
 	int reset_type = NONE, update_ref_status = 0, quiet = 0;
@@ -294,7 +302,7 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 		OPT_END()
 	};
 
-	git_config(git_default_config, NULL);
+	git_config(git_reset_config, NULL);
 
 	argc = parse_options(argc, argv, prefix, options, git_reset_usage,
 						PARSE_OPT_KEEP_DASHDASH);

submodule.c

@@ -16,6 +16,7 @@
 #include "quote.h"
 #include "remote.h"
 #include "worktree.h"
+#include "parse-options.h"
 
 static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
 static int config_update_recurse_submodules = RECURSE_SUBMODULES_OFF;
@@ -170,10 +171,28 @@ static int git_modules_config(const char *var, const char *value, void *cb)
 	return 0;
 }
 
-/* Loads all submodule settings from the config */
+/* Loads all submodule settings from the config. */
 int submodule_config(const char *var, const char *value, void *cb)
 {
-	return git_modules_config(var, value, cb);
+	if (!strcmp(var, "submodule.recurse")) {
+		int v = git_config_bool(var, value) ?
+			RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
+		config_update_recurse_submodules = v;
+		return 0;
+	} else {
+		return git_modules_config(var, value, cb);
+	}
+}
+
+/* Cheap function that only determines if we're interested in submodules at all */
+int git_default_submodule_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "submodule.recurse")) {
+		int v = git_config_bool(var, value) ?
+			RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
+		config_update_recurse_submodules = v;
+	}
+	return 0;
 }
 
 int option_parse_recurse_submodules_worktree_updater(const struct option *opt,

submodule.h

@@ -39,6 +39,7 @@ extern void stage_updated_gitmodules(void);
 extern void set_diffopt_flags_from_submodule_config(struct diff_options *,
 		const char *path);
 extern int submodule_config(const char *var, const char *value, void *cb);
+extern int git_default_submodule_config(const char *var, const char *value, void *cb);
 
 struct option;
 int option_parse_recurse_submodules_worktree_updater(const struct option *opt,

t/lib-submodule-update.sh

@@ -990,6 +990,18 @@ test_submodule_switch_recursing_with_args () {
 		)
 	'
 
+	test_expect_success "git -c submodule.recurse=true $cmd_args: modified submodule updates submodule work tree" '
+		prolog &&
+		reset_work_tree_to_interested add_sub1 &&
+		(
+			cd submodule_update &&
+			git branch -t modify_sub1 origin/modify_sub1 &&
+			git -c submodule.recurse=true $cmd_args modify_sub1 &&
+			test_superproject_content origin/modify_sub1 &&
+			test_submodule_content sub1 origin/modify_sub1
+		)
+	'
+
 	# Updating a submodule to an invalid sha1 doesn't update the
 	# superproject nor the submodule's work tree.
 	test_expect_success "$command: updating to a missing submodule commit fails" '