git-commit-vandalism/Documentation/merge-strategies.txt
Justin Frankel 58a1ece478 merge-recursive --patience
Teach the merge-recursive strategy a --patience option to use the
"patience diff" algorithm, which tends to improve results when
cherry-picking a patch that reorders functions at the same time as
refactoring them.

To support this, struct merge_options and ll_merge_options gain an
xdl_opts member, so programs can use arbitrary xdiff flags (think
"XDF_IGNORE_WHITESPACE") in a git-aware merge.

git merge and git rebase can be passed the -Xpatience option to
use this.

[jn: split from --ignore-space patch; with documentation]

Signed-off-by: Justin Frankel <justin@cockos.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-08-26 09:20:03 -07:00

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MERGE STRATEGIES
----------------
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'.
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 and is considered generally safe and
fast.
recursive::
This 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 mis-merges by tests done on actual merge commits
taken from Linux 2.6 kernel development history.
Additionally this can detect and handle merges involving
renames. This is the default merge strategy when
pulling or merging one branch.
+
The 'recursive' 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 to the merge result.
+
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 opposite of 'ours'.
patience;;
With this option, 'merge-recursive' spends a little extra time
to avoid mismerges that sometimes occur due to unimportant
matching lines (e.g., braces from distinct functions). Use
this when the branches to be merged have diverged wildly.
See also linkgit:git-diff[1] `--patience`.
renormalize;;
This runs a virtual check-out and check-in of all three stages
of a file when resolving 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
linkgit:gitattributes[5] for details.
no-renormalize;;
Disables the `renormalize` option. This overrides the
`merge.renormalize` configuration variable.
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.
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 'recursive' merge strategy.
subtree::
This is a modified recursive 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.