The commit-msg hook is not invoked by git-merge as specified in documentation

Hello,

At least two places in the git docs it is specified that the hook "commit-msg" is invoked by both git-commit and git-merge.

https://git-scm.com/docs/githooks#_commit_msg https://git-scm.com/docs/git-merge#Documentation/git-merge.txt---no-verify

I'm experiencing a different behavior however. The hook seems to work fine on git-commit, but is not invoked by git-merge. When I use git-merge my text editor opens with the default message, but when I close the editor the hook is not invoked as I would expect.

For reference, the prepare-commit-msg hook works with both commands as expected.

Is there something subtle I'm overlooking? Of course a fast forward merge should not invoke the commit-msg hook, because no commit is made. But in my tests with non FF-merges the hook is still not invoked.

Kind regards, Kalle Kromann This is an e-mail from MAN Energy Solutions, branch of MAN Energy Solutions SE, Germany (CVR no. 31611792). This e-mail (including any attachments) is confidential and may be privileged. If you have received this e-mail by mistake, please notify the sender by e-mail and delete it from your system. Any unauthorized use or dissemination of this e-mail or its contents in whole or in part is strictly prohibited. Please note that e-mails are susceptible to change. MAN Energy Solutions SE (including its group companies) shall not be liable for improper or incomplete transmission of the information contained in this e-mail or for any delay in its receipt. MAN Energy Solutions SE (or its group companies) does not guarantee that this e-mail has not been compromised or that it is free of viruses, interceptions or interference.

Kalle Kromann <kalle.kromann@man-es.com> writes:

On what platform, and which version of Git are we talking about? What is the difference between these two hooks? I.e. perhaps

    $ ls -l .git/hooks/prepare-commit-msg .git/hooks/commit-msg

tells you some subtle differences between the two?

Other than the last one, nothing comes to my mind. And it does not reproduce for me.

I just did this:

    $ echo exit 1 >.git/hooks/commit-msg
    $ chmod +x .git/hooks/commit-msg
    $ git checkout master^0
    $ git merge ds/line-log-on-bloom
	    ... editor launches and I save the message ...
    Auto-merging revision.c
    Auto-merging line-log.c
    Auto-merging bloom.h
    Auto-merging bloom.c
    Not committing merge; use 'git commit' to complete the merge.

The last line comes from builtin/merge.c::abort_commit(), which is called from this piece of code in builtin/merge.c::prepare_to_commit()

	if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
			    git_path_merge_msg(the_repository), "merge", NULL))
		abort_commit(remoteheads, NULL);
	if (0 < option_edit) {
		if (launch_editor(git_path_merge_msg(the_repository), NULL, NULL))
			abort_commit(remoteheads, NULL);
	}

	if (!no_verify && run_commit_hook(0 < option_edit, get_index_file(),
					  "commit-msg",
					  git_path_merge_msg(the_repository), NULL))
		abort_commit(remoteheads, NULL);

I do not have prepare-commit-msg, and my launch_editor() thing successfully returned, and the call to abort_commit() is cleraly coming from the last line, where run_commit_hook() noticed that the commit-msg hook ran and reported a failure.

After this, I did this to just confirm:

    $ echo exit 0 >.git/hooks/commit-msg
    $ git reset --hard
    $ git merge ds/line-log-on-bloom

This time, instead of "Not committing...", I got

    Merge made by the 'recursive' strategy.

followed by the usual diffstat.

The above demonstrates that commit-msg does run well enough to cause its exit status affects the outcome in both cases.

For fun, I tried another.

    $ echo exit 1 >.git/hooks/commit-msg
    $ chmod -x .git/hooks/commit-msg
    $ git reset --hard master
    $ GIT_EDITOR=: git merge ds/line-log-on-bloom
    Auto-merging revision.c
    Auto-merging line-log.c
    Auto-merging bloom.h
    Auto-merging bloom.c
    hint: The '.git/hooks/commit-msg' hook was ignored because it's not set as executable.
    hint: You can disable this warning with `git config advice.ignoredHook false`.
    Merge made by the 'recursive' strategy.
    ... diffstat follows ...

So...

Hello, thanks for the reply.

Sorry for not including it originally, the platform I was using to test was WSL (Windows subsystem for Linux). And the git version was the latest available from apt-get in WSL, 2.7.4.

It seems like one of these things is affecting the execution of the hook. I just did the exact same test in Cygwin with git version 2.17 and it works as expected here.

Do you know if it's a recent change that git-merge should invoke the hook as well? Or do you think it is related to using git in WSL?

Thanks again! This is an e-mail from MAN Energy Solutions, branch of MAN Energy Solutions SE, Germany (CVR no. 31611792). This e-mail (including any attachments) is confidential and may be privileged. If you have received this e-mail by mistake, please notify the sender by e-mail and delete it from your system. Any unauthorized use or dissemination of this e-mail or its contents in whole or in part is strictly prohibited. Please note that e-mails are susceptible to change. MAN Energy Solutions SE (including its group companies) shall not be liable for improper or incomplete transmission of the information contained in this e-mail or for any delay in its receipt. MAN Energy Solutions SE (or its group companies) does not guarantee that this e-mail has not been compromised or that it is free of viruses, interceptions or interference.

Kalle Kromann <kalle.kromann@man-es.com> writes:

Wow, that's ancient.  

"git merge" started calling commit-msg hook f8b86359 (builtin/merge: honor commit-msg hook for merges, 2017-09-07), which first appeared in 2.15 (from Oct 2017, that is also ancient in Git timescale) IIUC.

Thank you so much for your help.

I'm still quite new to git, and this was definitely a rookie mistake. This is an e-mail from MAN Energy Solutions, branch of MAN Energy Solutions SE, Germany (CVR no. 31611792). This e-mail (including any attachments) is confidential and may be privileged. If you have received this e-mail by mistake, please notify the sender by e-mail and delete it from your system. Any unauthorized use or dissemination of this e-mail or its contents in whole or in part is strictly prohibited. Please note that e-mails are susceptible to change. MAN Energy Solutions SE (including its group companies) shall not be liable for improper or incomplete transmission of the information contained in this e-mail or for any delay in its receipt. MAN Energy Solutions SE (or its group companies) does not guarantee that this e-mail has not been compromised or that it is free of viruses, interceptions or interference.