Documentation/merge-strategies.txt

   1 MERGE STRATEGIES
   2 ----------------
   3
   4 The merge mechanism ('git-merge' and 'git-pull' commands) allows the
   5 backend 'merge strategies' to be chosen with `-s` option.  Some strategies
   6 can also take their own options, which can be passed by giving `-X<option>`
   7 arguments to 'git-merge' and/or 'git-pull'.
   8
   9 resolve::
  10         This can only resolve two heads (i.e. the current branch
  11         and another branch you pulled from) using a 3-way merge
  12         algorithm.  It tries to carefully detect criss-cross
  13         merge ambiguities and is considered generally safe and
  14         fast.
  15
  16 recursive::
  17         This can only resolve two heads using a 3-way merge
  18         algorithm.  When there is more than one common
  19         ancestor that can be used for 3-way merge, it creates a
  20         merged tree of the common ancestors and uses that as
  21         the reference tree for the 3-way merge.  This has been
  22         reported to result in fewer merge conflicts without
  23         causing mis-merges by tests done on actual merge commits
  24         taken from Linux 2.6 kernel development history.
  25         Additionally this can detect and handle merges involving
  26         renames.  This is the default merge strategy when
  27         pulling or merging one branch.
  28 +
  29 The 'recursive' strategy can take the following options:
  30
  31 ours;;
  32         This option forces conflicting hunks to be auto-resolved cleanly by
  33         favoring 'our' version.  Changes from the other tree that do not
  34         conflict with our side are reflected to the merge result.
  35         For a binary file, the entire contents are taken from our side.
  36 +
  37 This should not be confused with the 'ours' merge strategy, which does not
  38 even look at what the other tree contains at all.  It discards everything
  39 the other tree did, declaring 'our' history contains all that happened in it.
  40
  41 theirs;;
  42         This is the opposite of 'ours'.
  43
  44 patience;;
  45         With this option, 'merge-recursive' spends a little extra time
  46         to avoid mismerges that sometimes occur due to unimportant
  47         matching lines (e.g., braces from distinct functions).  Use
  48         this when the branches to be merged have diverged wildly.
  49         See also linkgit:git-diff[1] `--patience`.
  50
  51 ignore-space-change;;
  52 ignore-all-space;;
  53 ignore-space-at-eol;;
  54         Treats lines with the indicated type of whitespace change as
  55         unchanged for the sake of a three-way merge.  Whitespace
  56         changes mixed with other changes to a line are not ignored.
  57         See also linkgit:git-diff[1] `-b`, `-w`, and
  58         `--ignore-space-at-eol`.
  59 +
  60 * If 'their' version only introduces whitespace changes to a line,
  61   'our' version is used;
  62 * If 'our' version introduces whitespace changes but 'their'
  63   version includes a substantial change, 'their' version is used;
  64 * Otherwise, the merge proceeds in the usual way.
  65
  66 renormalize;;
  67         This runs a virtual check-out and check-in of all three stages
  68         of a file when resolving a three-way merge.  This option is
  69         meant to be used when merging branches with different clean
  70         filters or end-of-line normalization rules.  See "Merging
  71         branches with differing checkin/checkout attributes" in
  72         linkgit:gitattributes[5] for details.
  73
  74 no-renormalize;;
  75         Disables the `renormalize` option.  This overrides the
  76         `merge.renormalize` configuration variable.
  77
  78 rename-threshold=<n>;;
  79         Controls the similarity threshold used for rename detection.
  80         See also linkgit:git-diff[1] `-M`.
  81
  82 subtree[=<path>];;
  83         This option is a more advanced form of 'subtree' strategy, where
  84         the strategy makes a guess on how two trees must be shifted to
  85         match with each other when merging.  Instead, the specified path
  86         is prefixed (or stripped from the beginning) to make the shape of
  87         two trees to match.
  88
  89 octopus::
  90         This resolves cases with more than two heads, but refuses to do
  91         a complex merge that needs manual resolution.  It is
  92         primarily meant to be used for bundling topic branch
  93         heads together.  This is the default merge strategy when
  94         pulling or merging more than one branch.
  95
  96 ours::
  97         This resolves any number of heads, but the resulting tree of the
  98         merge is always that of the current branch head, effectively
  99         ignoring all changes from all other branches.  It is meant to
 100         be used to supersede old development history of side
 101         branches.  Note that this is different from the -Xours option to
 102         the 'recursive' merge strategy.
 103
 104 subtree::
 105         This is a modified recursive strategy. When merging trees A and
 106         B, if B corresponds to a subtree of A, B is first adjusted to
 107         match the tree structure of A, instead of reading the trees at
 108         the same level. This adjustment is also done to the common
 109         ancestor tree.