Re: New Git hooks for checking file names in commit messages

[Alan Mackenzie <acm@muc.de>]

Hello, Jim.

On Thu, Apr 20, 2023 at 21:55:15 -0700, Jim Porter wrote:

[ .... ]

> There's one part that might be surprising, at least initially though:
> while this is a hook to check commit messages, it actually runs in the
> post-commit and pre-push phases. This is because we want to examine
> the full diff of the commit in order to compare against the file
> entries in the message.[1] As a result, you'll just get an advisory
> message when you make the commit (it's too late to error out), and the
> pre-push hook will prevent you from pushing a badly-formatted commit
> message upstream.

How is this helpful?  Telling somebody they've made a mistake is only
helpful if they can correct it.  If "it's too late to error out", it
will just create annoyance.  Immediately after such a commit it is
possible to use $ git commit --amend, but not later.  And preventing
people from pushing these erroneous commits is, again, not helpful.  It
will likely take more work, in total, somehow to correct these errors
(how?) than it took Eli to correct all the commit message mistakes for
the Emacs-29.1 pretest release.

I don't understand why the checking of the commit message isn't done in
the commit-msg hook.

[ .... ]

> [1] It's hard to do this during the commit-msg hook since there's no 
> cross-platform way I know of to handle amending commits properly.

I don't understand this bit.  Why does the lack of a way of amending
commits make it difficult to error out from the commit-msg hook?  What
am I missing?

-- 
Alan Mackenzie (Nuremberg, Germany).