Re: [PATCH v2 1/1] submodule foreach: fix recursion of options

Hi Morian,

On Tue, 18 Jun 2019, Morian Sonnet wrote:

This is a good explanation, even if the format is not exactly close to the existing commit messages ;-) If you look e.g. at https://github.com/git/git/commit/e5a329a279c7, you will see what I mean: there is much more "prose" (and less bullet points) going on.

This is obviously correct.

I am terribly sorry that I did not catch this in the first round. I would find it even easier to read if it used the `-C` option, like so:

	git -C super submodule foreach --recursive git reset --hard

Then you do not need the subshell, and neither the `cd`. It would become a one-liner.

However, what is less obvious to me is that this would catch the regression, as I do not see from the context whether the current submodule structure is deep enough to trigger the reported problem. If I understand the commit message correctly, `super` would have to contain a submodule that itself contains a submodule.

If there was only one level of submodules (and from the context of this diff, it is not clear whether that is the case), the test case would pass even without the code change to `submodule.c`.

Of course, I can always dig deeper and find out myself (and of course I did exactly that). But in my mind, that points to something we can improve.

What I found is that the test case indeed fails without the fixed `builtin/submodule.c`, but that the nested submodule does not even need to be checked out, contrary to what I expected after reading the commit message.

And in fact, the nested submodule is not even checked out in the test script!

To make this test case more obvious, and at the same time to test a little more thoroughly, maybe it would make sense to initialize that "inner" submodule (in this test script, `super/nested1/nested2`), then make it dirty by changing a file before the `reset --hard`, and afterwards verify that the file in question was successfully reset.

That way, the test case would start to fail if anybody changed the script in a way where the submodule nesting was all of a sudden no longer deep enough to verify what the test case wants to verify.

Otherwise we would risk that this test case would start passing for the wrong reasons at some stage.

What I have in mind would look somewhat like this:

	: make sure that nested2 is initialized &&
	git -C super/nested1 submodule update --init nested2 &&

	: make sure that nested2 is dirty &&
	echo dirty >super/nested1/nested2/file &&
	test_must_fail git -C super/nested1/nested2 update-index --refresh &&

	git -C super submodule foreach --recursive git reset --hard &&
	: now nested2 is clean &&
	git -C super/nested1/nested2 update-index --refresh

I might be overthinking this, though. Maybe it would be enough to make sure that nested1/nested2 is a nested submodule, e.g. by something like this:

	is_submodule () {
		case "$(git -C "${1%/*}" ls-files --stage "${1##*/}")" in
		160000*) return 0;;
		*) return 1;;
		esac
	} &&
	is_submodule super/nested1 &&
	is_submodule super/nested1/nested2 &&
	git -C super submodule foreach --recursive git reset --hard

which has the advantage of looking shorter, but it does not really verify that `git reset --hard` *has* been working correctly in nested2: it did not, as that nested submodule was not even initialized at that point.

So I dunno... What do you think? How can we make this test case both more understandable and more robust against future edits at the same time?

Ciao, Johannes