On Fri, Sep 17 2021, Junio C Hamano wrote: > Kurt von Laven <kurt.von.laven@xxxxxxxxx> writes: > >> The most common reason commit messages are left empty is to abort >> them. commit-msg hooks that replace empty commit messages with >> non-empty ones (i) make it impossible to abort commits, (ii) are >> startling to developers joining a project configured in this manner, >> and (iii) can offer no value that wouldn't be equally or better >> offered another way. For instance, a default commit message would be >> better implemented as a commit message template or prepare-commit-msg >> hook. I propose that Git eventually cease calling commit-msg hooks >> when the commit-message is empty, but I would understand if backwards >> compatibility were the overriding concern. On the other hand, the >> empty commit message case is easy to overlook when crafting a >> commit-msg hook. One consequence of this behavior is that running the >> popular pre-commit tool (https://pre-commit.com/) tends to lead to a >> spew of false positives to the console on an aborted commit when >> configured with commit-msg hooks. > > The primary reason commit-msg hook is there is *not* because we need > a way to tweak the log message. As you said, prepare-commit-msg and > templates are much better way to give some sort of default. > > The purpose of the hook is to serve as the gatekeeper to cause an > attempt with a bad commit message to fail. And a properly written > commit-msg hook would be rejecting an empty message, instead of > inserting cruft into an empty message file. > > So, from that point of view, if we were to change anything, a more > useful thing to do might be to forbid commit-msg hook from modifying > the file and make sure it would only verify but not modify, I > suspect. Doing so would have a side effect of making sure that no > commit-msg hook will turn an empty message file into a non-empty > message file ;-). I'd think we'd want to call it on an empty message, e.g. maybe someone depends on that with empty message = auto-generate a message for me. But for those that don't, doesn't the default behavior of "git commit" catch this in either case, i.e. it wouldn't let it pass without --allow-empty-message. I understood this report as the hook taking the empty message (e.g. the user using it as a shorthand to abort), and their hook "helpfully" inserting some "default" message or template.
