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VOOZH | about |
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VOOZH | about |
The merge mechanism (git merge and git pull commands) allows the
backend merge strategies to be chosen with -s option. Some strategies
can also take their own options, which can be passed by giving -X<option>
arguments to git merge and/or git pull.
ort This is the default merge strategy when pulling or merging one
branch. This strategy can only resolve two heads using a
3-way merge algorithm. When there is more than one common
ancestor that can be used for 3-way merge, it creates a merged
tree of the common ancestors and uses that as the reference
tree for the 3-way merge. This has been reported to result in
fewer merge conflicts without causing mismerges by tests done
on actual merge commits taken from Linux 2.6 kernel
development history. Additionally this strategy can detect
and handle merges involving renames. It does not make use of
detected copies. The name for this algorithm is an acronym
("Ostensibly Recursive’s Twin") and came from the fact that it
was written as a replacement for the previous default
algorithm, recursive.
In the case where the path is a submodule, if the submodule commit used on one side of the merge is a descendant of the submodule commit used on the other side of the merge, Git attempts to fast-forward to the descendant. Otherwise, Git will treat this case as a conflict, suggesting as a resolution a submodule commit that is descendant of the conflicting ones, if one exists.
The ort strategy can take the following options:
ours This option forces conflicting hunks to be auto-resolved cleanly by favoring our version. Changes from the other tree that do not conflict with our side are reflected in the merge result. For a binary file, the entire contents are taken from our side.
This should not be confused with the ours merge strategy, which does not
even look at what the other tree contains at all. It discards everything
the other tree did, declaring our history contains all that happened in it.
theirs This is the opposite of ours; note that, unlike ours, there is
no theirs merge strategy to confuse this merge option with.
ignore-space-change ignore-all-space ignore-space-at-eol ignore-cr-at-eol Treats lines with the indicated type of whitespace change as
unchanged for the sake of a three-way merge. Whitespace
changes mixed with other changes to a line are not ignored.
See also git-diff[1] -b, -w,
--ignore-space-at-eol, and --ignore-cr-at-eol.
If their version only introduces whitespace changes to a line, our version is used;
If our version introduces whitespace changes but their version includes a substantial change, their version is used;
Otherwise, the merge proceeds in the usual way.
renormalize This runs a virtual check-out and check-in of all three stages of any file which needs a three-way merge. This option is meant to be used when merging branches with different clean filters or end-of-line normalization rules. See "Merging branches with differing checkin/checkout attributes" in gitattributes[5] for details.
no-renormalize Disables the renormalize option. This overrides the
merge.renormalize configuration variable.
find-renames[=<n>] Turn on rename detection, optionally setting the similarity
threshold. This is the default. This overrides the
merge.renames configuration variable.
See also git-diff[1] --find-renames.
rename-threshold=<n> Deprecated synonym for find-renames=<n>.
no-renames Turn off rename detection. This overrides the merge.renames
configuration variable.
See also git-diff[1] --no-renames.
histogram Deprecated synonym for diff-algorithm=histogram.
patience Deprecated synonym for diff-algorithm=patience.
diff-algorithm=(histogram|minimal|myers|patience) Use a different diff algorithm while merging, which can help
avoid mismerges that occur due to unimportant matching lines
(such as braces from distinct functions). See also
git-diff[1] --diff-algorithm. Note that ort
defaults to diff-algorithm=histogram, while regular diffs
currently default to the diff.algorithm config setting.
subtree[=<path>] This option is a more advanced form of subtree strategy, where the strategy makes a guess on how two trees must be shifted to match with each other when merging. Instead, the specified path is prefixed (or stripped from the beginning) to make the shape of two trees to match.
recursive This is now a synonym for ort. It was an alternative
implementation until v2.49.0, but was redirected to mean ort
in v2.50.0. The previous recursive strategy was the default
strategy for resolving two heads from Git v0.99.9k until
v2.33.0.
resolve This can only resolve two heads (i.e. the current branch and another branch you pulled from) using a 3-way merge algorithm. It tries to carefully detect criss-cross merge ambiguities. It does not handle renames.
octopus This resolves cases with more than two heads, but refuses to do a complex merge that needs manual resolution. It is primarily meant to be used for bundling topic branch heads together. This is the default merge strategy when pulling or merging more than one branch.
ours This resolves any number of heads, but the resulting tree of the
merge is always that of the current branch head, effectively
ignoring all changes from all other branches. It is meant to
be used to supersede old development history of side
branches. Note that this is different from the -Xours option to
the ort merge strategy.
subtree This is a modified ort strategy. When merging trees A and
B, if B corresponds to a subtree of A, B is first adjusted to
match the tree structure of A, instead of reading the trees at
the same level. This adjustment is also done to the common
ancestor tree.
With the strategies that use 3-way merge (including the default, ort),
if a change is made on both branches, but later reverted on one of the
branches, that change will be present in the merged result; some people find
this behavior confusing. It occurs because only the heads and the merge base
are considered when performing a merge, not the individual commits. The merge
algorithm therefore considers the reverted change as no change at all, and
substitutes the changed version instead.