Re: Bug in git submodule update --remote

[Ben Avison <bavison@riscosopen.org>]

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'")"