fetch/pull: recurse into submodules when necessary

To be able to access all commits of populated submodules referenced by the
superproject it is sufficient to only then let "git fetch" recurse into a
submodule when the new commits fetched in the superproject record new
commits for it. Having these commits present is extremely useful when
using the "--submodule" option to "git diff" (which is what "git gui" and
"gitk" do since 1.6.6), as all submodule commits needed for creating a
descriptive output can be accessed. Also merging submodule commits (added
in 1.7.3) depends on the submodule commits in question being present to
work. Last but not least this enables disconnected operation when using
submodules, as all commits necessary for a successful "git submodule
update -N" will have been fetched automatically. So we choose this mode as
the default for fetch and pull.

Before a new or changed ref from upstream is updated in update_local_ref()
"git rev-list <new-sha1> --not --branches --remotes" is used to determine
all newly fetched commits. These are then walked and diffed against their
parent(s) to see if a submodule has been changed. If that is the case, its
path is stored to be fetched after the superproject fetch is completed.

Using the "--recurse-submodules" or the "--no-recurse-submodules" option
disables the examination of the fetched refs because the result will be
ignored anyway.

There is currently no infrastructure for storing deleted and new
submodules in the .git directory of the superproject. That's why fetch and
pull for now only fetch submodules that are already checked out and are
not renamed.

In t7403 the "--no-recurse-submodules" argument had to be added to "git
pull" to avoid failure because of the moved upstream submodule repo.

Thanks-to: Jonathan Nieder <jrnieder@gmail.com>
Thanks-to: Heiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 17 insertions, 9 deletions

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 357f3cdbbf..23c249dbfb 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -28,12 +28,6 @@ enum {
 	TAGS_SET = 2
 };
 
-enum {
-	RECURSE_SUBMODULES_OFF = 0,
-	RECURSE_SUBMODULES_DEFAULT = 1,
-	RECURSE_SUBMODULES_ON = 2
-};
-
 static int all, append, dry_run, force, keep, multiple, prune, update_head_ok, verbosity;
 static int progress, recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
 static int tags = TAGS_DEFAULT;
@@ -42,6 +36,7 @@ static const char *upload_pack;
 static struct strbuf default_rla = STRBUF_INIT;
 static struct transport *transport;
 static const char *submodule_prefix = "";
+static const char *recurse_submodules_default;
 
 static struct option builtin_fetch_options[] = {
 	OPT__VERBOSITY(&verbosity),
@@ -73,6 +68,9 @@ static struct option builtin_fetch_options[] = {
 		   "deepen history of shallow clone"),
 	{ OPTION_STRING, 0, "submodule-prefix", &submodule_prefix, "DIR",
 		   "prepend this to submodule path output", PARSE_OPT_HIDDEN },
+	{ OPTION_STRING, 0, "recurse-submodules-default",
+		   &recurse_submodules_default, NULL,
+		   "default mode for recursion", PARSE_OPT_HIDDEN },
 	OPT_END()
 };
 
@@ -284,6 +282,9 @@ static int update_local_ref(struct ref *ref,
 		else {
 			msg = "storing head";
 			what = "[new branch]";
+			if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
+			    (recurse_submodules != RECURSE_SUBMODULES_ON))
+				check_for_new_submodule_commits(ref->new_sha1);
 		}
 
 		r = s_update_ref(msg, ref, 0);
@@ -299,6 +300,9 @@ static int update_local_ref(struct ref *ref,
 		strcpy(quickref, find_unique_abbrev(current->object.sha1, DEFAULT_ABBREV));
 		strcat(quickref, "..");
 		strcat(quickref, find_unique_abbrev(ref->new_sha1, DEFAULT_ABBREV));
+		if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
+		    (recurse_submodules != RECURSE_SUBMODULES_ON))
+			check_for_new_submodule_commits(ref->new_sha1);
 		r = s_update_ref("fast-forward", ref, 1);
 		sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : ' ',
 			TRANSPORT_SUMMARY_WIDTH, quickref, REFCOL_WIDTH, remote,
@@ -310,6 +314,9 @@ static int update_local_ref(struct ref *ref,
 		strcpy(quickref, find_unique_abbrev(current->object.sha1, DEFAULT_ABBREV));
 		strcat(quickref, "...");
 		strcat(quickref, find_unique_abbrev(ref->new_sha1, DEFAULT_ABBREV));
+		if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
+		    (recurse_submodules != RECURSE_SUBMODULES_ON))
+			check_for_new_submodule_commits(ref->new_sha1);
 		r = s_update_ref("forced-update", ref, 1);
 		sprintf(display, "%c %-*s %-*s -> %s  (%s)", r ? '!' : '+',
 			TRANSPORT_SUMMARY_WIDTH, quickref, REFCOL_WIDTH, remote,
@@ -949,9 +956,10 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 	if (!result && (recurse_submodules != RECURSE_SUBMODULES_OFF)) {
 		const char *options[10];
 		int num_options = 0;
-		/* Set recursion as default when we already are recursing */
-		if (submodule_prefix[0])
-			set_config_fetch_recurse_submodules(1);
+		if (recurse_submodules_default) {
+			int arg = parse_fetch_recurse_submodules_arg("--recurse-submodules-default", recurse_submodules_default);
+			set_config_fetch_recurse_submodules(arg);
+		}
 		gitmodules_config();
 		git_config(submodule_config, NULL);
 		add_options_to_argv(&num_options, options);