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Is there a way to identify "collateral" commits (commits that are editing same lines and will result in a conflict) for the certain commit?

A very simplified example

$ git init
$ echo test > test
$ git add test
$ git commit -m "First commit"
$ echo test1 > test
$ git commit -am "Second commit"
$ git l
* 95a29dd Second commit
* 30a68e6 First commit
$ type test
test1

Assuming that at this point for whatever reason I want to revert 30a68e6.

$ git revert 30a68e6
error: could not revert 30a68e6... First commit
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'

Naturally, this will result in a conflict, since 95a29dd, edited the same line.

Is it possible to find out in advance that reverting 30a68e6 would result in a conflict, and if so, with what commit (i.e. 95a29dd)?

To give a bit of context, I need this, because I need some commits to be reverted automatically. In this case, if I know that 30a68e6 should be reverted, I want to be able to identify "collateral" commits, that should be reverted first to avoid any conflict (like 30a68e6). I know that just reverting everything 30a68e6..HEAD, would work, but I would like to avoid reverting commits that will not conflict with 30a68e6.

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2 Answers 2

Reset to default
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(Disclaimer: This answer is similar to my answer to Is there some kind of 'git rebase --dry-run', which would notify me of conflicts in advance?.)

Is it possible to find out in advance that reverting 30a68e6 would result in a conflict, and if so, with what commit (i.e. 95a29dd)?

At the time of writing (Git v2.7.0), Git provides no way of finding out, before actually attempting a revert, whether or not you're going to run into conflicts.

However, if you run git revert and hit a conflict, the process will stop and exit with a nonzero status. What you could do is check the exit status of the revert operation, and, if it is nonzero, run git revert --abort to cancel the revert:

git revert ... || git revert --abort

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  • Thanks for the answer. This works partially, because it still doesn't allow me to find out which commit was causing the conflict. Or am I missing something?
    – romants
    Commented Jan 12, 2016 at 20:40
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git revert should be easy to undo. Check the return code of the revert, and run git revert --abort if it failed (return code 1) or git reset --hard HEAD~1 if it succeded (return code 0) and you don't want to keep it.

You might be able to combine it with git bisect to search through the history, depending on your needs.

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  • I know how to undo git revert, but that give me no information what commits were conflicting
    – romants
    Commented Jan 8, 2016 at 21:47
  • I think the merging algorithm doesn't look at intervening commits, so you might have to find some way to manually test the intervening commits, either with bisect or with something else.
    – oyvind
    Commented Jan 8, 2016 at 23:13
  • This might be of interest: stackoverflow.com /q/8435343/1463246. It's about git log for lines.
    – oyvind
    Commented Jan 8, 2016 at 23:17

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