Imagine a merge where one side changes the content of a path and the
other changes the mode. Here's a minimal reproduction:
git init repo && cd repo &&
echo base >file &&
git add file &&
git commit -m base &&
echo changed >file &&
git commit -am content &&
git checkout -b side HEAD^
chmod +x file &&
git commit -am mode
If I merge that with merge-recursive, I get what you'd expect: mode
10755, and content "changed".
However, with merge-resolve, I get a conflict:
$ git merge -s resolve master
Trying really trivial in-index merge...
error: Merge requires file-level merging
Nope.
Trying simple merge.
Simple merge failed, trying Automatic merge.
Auto-merging file
ERROR: permissions conflict: 100644->100755,100644 in file
fatal: merge program failed
Automatic merge failed; fix conflicts and then commit the result.
I think this is only a half-bug, really. It's definitely a funny
situation, and it's not unreasonable for a merge driver to punt on a
funny situation rather than resolving it. But I would say:
- it would probably be a nice improvement to resolve this as
merge-recursive does
- the "ERROR" message is silly and misleading; the permissions resolve
just fine, it is only that the combination with the content-level
change confuses the script (but the output does not mention that).
This is a leftover from my experiments with merge-resolve versus
merge-recursive last fall, which resulted in a few actual bug-fixes. I
looked into fixing this case, too, at that time. It seemed possible, but
a little more involved than you might think (because the logic is driven
by a bunch of case statements, and this adds a multiplicative layer to
the cases; we might need to resolve the permissions, and _then_ see if
the content can be resolved).
So I didn't actually come up with a patch, but I figured I'd write it up
here for posterity. And just didn't get around to it until now.
-Peff
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