The update-index plumbing command had a hacky --unresolve implementation
that was written back in the days when merge was the only way for users to
end up with higher stages in the index, and assumed that stage #2 must
have come from HEAD, stage #3 from MERGE_HEAD and didn't bother to compute
the stage #1 information.
There were several issues with this approach:
- These days, merge is not the only command, and conflicts coming from
commands like cherry-pick, "am -3", etc. cannot be recreated by looking
at MERGE_HEAD;
- For a conflict that came from a merge that had renames, picking up the
same path from MERGE_HEAD and HEAD wouldn't help recreating it, either;
- It may have been Ok not to recreate stage #1 back when it was written,
because "diff --ours/--theirs" were the only availble ways to review
conflicts and they don't need stage #1 information. "diff --cc" that
was invented much later is a lot more useful way but it needs stage #1.
We can use resolve-undo information recorded in the index extension to
solve all of these issues.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Once you resolved conflicts by "git add path", you cannot recreate the
conflicted state with "git checkout -m path", because you lost information
from higher stages in the index when you resolved them.
Since we record the necessary information in the resolve-undo index
extension these days, we can reproduce the unmerged state in the index and
check it out.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
At the Porcelain level, operations such as merge that populate an
initially cleanly merged index with conflicted entries clear the
resolve-undo information upfront. Give scripted Porcelains a way
to do the same, by implementing "update-index --clear-resolve-info".
With this, a scripted Porcelain may "update-index --clear-resolve-info"
first and repeatedly run "update-index --cacheinfo" to stuff unmerged
entries to the index, to be resolved by the user with "git add" and
stuff.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make sure that resolving a failed merge with git add records
the conflicted state, committing the result keeps that state,
and checking out another commit clears the state.
"git ls-files" learns a new option --resolve-undo to show the
recorded information.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
