Re: Bug in git submodule update --remote

On 19/05/2021 11:49, Atharva Raykar wrote:

If I understood you correctly, you'd prefer that the updating of the
submodule should be independent of the ref that is checked out in the
submodule's directory.

While I am not sure of the reason why the design of 'update
--remote' uses the remote-tracking branch of the submodule, I can
imagine adding a switch like 'submodule.<name>.remote' that defaults
to 'origin'. Then the behaviour could be changed such that it always 
pulls from the remote specified in that option.

This would help make the behaviour consistent in all the cases you 
mentioned, while also giving the option for a user to update the 
submodule from the remote of their choice (which may not be origin).

I like that solution. Although, I should note that if the user has set
submodule.<name>.remote to something other than 'origin', they will need
to ensure that submodule.<name>.branch is also set, or they will still
hit the "Unable to find current <remote>/HEAD revision in submodule"
error that I initially stumbled on.

How about an implementation like the following? I introduced a new "git
submodule--helper" command rather than modify "print-default-remote" for
a couple of reasons:

1) "print-default-remote" is also used for "git submodule sync" (I'm not
sure if we should change its behaviour too)

2) "print-default-remote" needs to be executed from within the
submodule, and takes no arguments, whereas I need to parse the
superproject's .git/config so need to be executed from the superproject
and take the submodule path as an argument

The two functions I added are heavily based on "git submodule--helper
remote-branch". However:

* Unlike with the branch name, I don't fall back to using the name for
the remote cached from when we read the .gitmodules file, if it isn't
found in .git/config. It doesn't make sense to me for the .gitmodules
file to include this information, as any new clones will only contain
"origin" remotes anyway.

* I removed "struct strbuf sb" since I don't think it's used.

Ben

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 9d505a6329..25ce3c8a1d 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c

@@ -2444,6 +2444,41 @@ static int resolve_remote_submodule_branch(int argc, const char **argv,
 	return 0;
 }
 
+static const char *remote_submodule_remote(const char *path)
+{
+	const struct submodule *sub;
+	const char *remote = NULL;
+	char *key;
+
+	sub = submodule_from_path(the_repository, &null_oid, path);
+	if (!sub)
+		return NULL;
+
+	key = xstrfmt("submodule.%s.remote", sub->name);
+	repo_config_get_string_tmp(the_repository, key, &remote);
+	free(key);
+
+	if (!remote)
+		return "origin";
+
+	return remote;
+}
+
+static int resolve_remote_submodule_remote(int argc, const char **argv,
+		const char *prefix)
+{
+	const char *ret;
+	if (argc != 2)
+		die("submodule--helper remote-remote takes exactly one arguments, got %d", argc);
+
+	ret = remote_submodule_remote(argv[1]);
+	if (!ret)
+		die("submodule %s doesn't exist", argv[1]);
+
+	printf("%s", ret);
+	return 0;
+}
+
 static int push_check(int argc, const char **argv, const char *prefix)
 {
 	struct remote *remote;

@@ -2770,6 +2805,7 @@ static struct cmd_struct commands[] = {
 	{"deinit", module_deinit, 0},
 	{"summary", module_summary, SUPPORT_SUPER_PREFIX},
 	{"remote-branch", resolve_remote_submodule_branch, 0},
+	{"remote-remote", resolve_remote_submodule_remote, 0},
 	{"push-check", push_check, 0},
 	{"absorb-git-dirs", absorb_git_dirs, SUPPORT_SUPER_PREFIX},
 	{"is-active", is_active, 0},

diff --git a/git-submodule.sh b/git-submodule.sh
index eb90f18229..4d0df1cf5a 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh

@@ -577,7 +577,7 @@ cmd_update()
 				fetch_in_submodule "$sm_path" $depth ||
 				die "$(eval_gettext "Unable to fetch in submodule path '\$sm_path'")"
 			fi
-			remote_name=$(sanitize_submodule_env; cd "$sm_path" && git submodule--helper print-default-remote)
+			remote_name=$(git submodule--helper remote-remote "$sm_path")
 			sha1=$(sanitize_submodule_env; cd "$sm_path" &&
 				git rev-parse --verify "${remote_name}/${branch}") ||
 			die "$(eval_gettext "Unable to find current \${remote_name}/\${branch} revision in submodule path '\$sm_path'")"