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

Sam Vilain [off-list ref] 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 <redacted>
---
 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.