Re: git commit --verbose shows incorrect diff when pre-commit hook is used to modify files

Fernando Chorney [off-list ref] writes:

Hmm looks like I forgot to send my reply to this back to the mailing list.

"Hmm, so I currently have it set to run vim as my commit editor, and
enter the message in there most of the time. I can definitely see
output from the hook into the shell before my vim editor loads up that
shows me the diff and lets me add in the commit message. This leads me
to believe that the pre-commit hook is being run before the editor
(with the diff) pops up."

Does anybody else have any insight to this issue?

I do not know if it counts as an insight, but the pre-* hooks, not
limited to pre-commit, were invented for the purpose of validating
the input to an operation so that the hooks can _reject_ if the
outcome anticipated does not satisfy project's conventions; the
purpose they were invented was not because the operations wanted to
allow the input to them.  So attempting to modify the tree in
pre-commit hook, for example, is outside the scope of its design and
I wouldn't be surprised if you get an unexpected result.