Re: [PATCH] templates: make example pre-commit hook verify submodule commits exist

[Junio C Hamano <gitster@pobox.com>]

Sam Vilain <sam.vilain@catalyst.net.nz> writes:

> With submodules it can be quite easy to end up with a situation where the
> version in the supermodule doesn't exist in the submodule.  Add to the
> example pre-commit hook a script which checks before every commit whether
> the submodule commit is likely to exist at the URL defined in the
> .gitmodules file.
>
> Signed-off-by: Sam Vilain <sam.vilain@catalyst.net.nz>
> ---
>  This should be useful for those using submodules.  Perhaps it should also
>  have an equivalent in the 'git submodule' command.

If I am a developer who is not interested in any of the submodules in the
project at all (i.e. I do not have any submodule checked out), my commits
will never touch any of the submodules.  In such a case, I shouldn't be
forced to fetch/clone the submodule nor have a checkout.

Which means...

> +# first, check that all submodule commits are available by a remote
> +# which has the same URL as the one they are listed in.
> +if [ -n "$GIT_WORK_TREE" ]
> +then
> +	cd "$GIT_WORK_TREE"
> +fi
> +
> +git ls-tree $(git write-tree) | grep commit |
> +while read mode type sha1 submodule
> +do

... the input fed to this while look utterly wrong.  At least, you should
be checking *new* commit that is introduced to the tree with this commit.

I didn't read the body of the while loop; no matter what it does, if its
input is wrong, its end result cannot be correct.