Ask HN: How often does Git merge make mistakes?

by iceman_w on 7/11/2015, 6:45:13 PM with 5 comments
I was working on an express app with a friend and git auto merged a file after I ran 'git pull'. There were no merge conflicts, but git added duplicate functions to a file after merge. I spent an hour trying to figure our what the problem was before realizing that git had made a mistake while merging.

I had never seen such a thing before. How often does something like this happen?

  • by gknoy on 7/11/2015, 7:20:15 PM

    I've never noticed that before, but it's possible that you both had added functions in different places:

        foo() ... ; original

    bar() ...  ; added by alice
    foo() ...

    foo() ...
    bar() ...  ; added by bob
    I haven't tried it, but I could imagine that being seen as separate text additions, and ending up with duplicates if git thinks it needs to merge them:

        bar() ... ; alice
    foo() ... ; original
    bar() ... ; bob
    You mentioned using `git pull`, which will actually merge things if it thinks it's necessary -- which can lead to tree differences. In practice, I've found it helpful to NEVER USE `git pull`. Rather, I advise using:

        git checkout master
    git fetch origin
    git merge origin/master --ff-only
    This will ensure that git only does "fast-forward" merges, and does not end up accidentally merging things - and keeps 'origin' as the system-of-record for what's been merged.