Ask HN: How often does Git merge make mistakes? 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? |
foo() ... ; original
bar() ... ; added by alice
foo() ...
foo() ...
bar() ... ; added by bob
bar() ... ; alice
foo() ... ; original
bar() ... ; bob
git checkout master
git fetch origin
git merge origin/master --ff-only
git config --global pull.ff only
instead, then you can use "git pull" without worries. Or,
git pull --ff-only
origin: A-B-C local: A-B-D
What is the recommended action? git pull --ff-only will fail, right? So should I be using git pull --rebase?
Remember you can play a lot with git; if you are not sure how it will turn out, checkout a commit (e.g. git checkout origin/master), create a new throwaway branch (git checkout -b tmp), then you can do rebases, cherry-picks, merges etc., then do "git log tmp" or "git log -p tmp" to see how does the branch look. If you are unhappy, you can always throw it out (git branch -D tmp), it won't affect anything else.
I generally avoid the situation when a branch and origin diverges. The flow I have in my work is: If I need to make a small change (few lines), I pull, do changes, commit and push directly to master; if there are any intervening independent changes, pull --rebase. For anything larger, I create a new branch, and commit there. Once it is ready, I give it to a teammate for code review and do automated build, if everything is OK he merges it to master. Other people generally don't push to my branch, and there is no A-B-C vs A-B-D situation.
If several people work together on the same branch, we coordinate actions face-to-face or via team chat, to avoid conflicts. We pull/push many times a day and the changes are small enough so there are no problems with rebasing in a topic branch. If two people make big conflicting changes to the same branch, it means trouble and we merge or even discard some changes.