merge - Are there any downsides to enabling git rerere?

Question

I've read various things about git's rerere feature, and I'm considering enabling it.

The git rerere functionality is a bit of a hidden feature. The name stands for “reuse recorded resolution” and, as the name implies, it allows you to ask Git to remember how you’ve resolved a hunk conflict so that the next time it sees the same conflict, Git can resolve it for you automatically.

https://git-scm.com/book/en/v2/Git-Tools-Rerere

But I haven't seen anyone mention any possible problems that could arise while using rerere.

I have to assume there is a downside, or it would probably be enabled by default. So is there any downside to enabling rerere? What potential problems can it cause that would not otherwise occur?

Answer 1

If you do a merge incorrectly, then discard it, then do the "same" merge again, it will be incorrect again. You can forget a recorded resolution, though. From the documentation:

git rerere forget <pathspec>

This resets the conflict resolutions which rerere has recorded for the current conflict in <pathspec>.

Be careful to use it on specific paths; you don't want to blow away all of your recorded resolutions everywhere. (forget with no arguments has been deprecated to save you from doing this, unless you type git rerere forget . to explicitly request it.)

But if you don't think to do that, you could easily end up putting that incorrect merge into your history..