Documentation / merge-strategies.txton commit git-svn: check_cherry_pick should exclude commits already in our history (a3c7505)
   1MERGE STRATEGIES
   2----------------
   3
   4The merge mechanism ('git-merge' and 'git-pull' commands) allows the
   5backend 'merge strategies' to be chosen with `-s` option.  Some strategies
   6can also take their own options, which can be passed by giving `-X<option>`
   7arguments to 'git-merge' and/or 'git-pull'.
   8
   9resolve::
  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
  16recursive::
  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+
  29The 'recursive' strategy can take the following options:
  30
  31ours;;
  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+
  36This should not be confused with the 'ours' merge strategy, which does not
  37even look at what the other tree contains at all.  It discards everything
  38the other tree did, declaring 'our' history contains all that happened in it.
  39
  40theirs;;
  41        This is opposite of 'ours'.
  42
  43renormalize;;
  44        This runs a virtual check-out and check-in of all three stages
  45        of a file when resolving a three-way merge.  This option is
  46        meant to be used when merging branches with different clean
  47        filters or end-of-line normalization rules.  See "Merging
  48        branches with differing checkin/checkout attributes" in
  49        linkgit:gitattributes[5] for details.
  50
  51no-renormalize;;
  52        Disables the `renormalize` option.  This overrides the
  53        `merge.renormalize` configuration variable.
  54
  55subtree[=path];;
  56        This option is a more advanced form of 'subtree' strategy, where
  57        the strategy makes a guess on how two trees must be shifted to
  58        match with each other when merging.  Instead, the specified path
  59        is prefixed (or stripped from the beginning) to make the shape of
  60        two trees to match.
  61
  62octopus::
  63        This resolves cases with more than two heads, but refuses to do
  64        a complex merge that needs manual resolution.  It is
  65        primarily meant to be used for bundling topic branch
  66        heads together.  This is the default merge strategy when
  67        pulling or merging more than one branch.
  68
  69ours::
  70        This resolves any number of heads, but the resulting tree of the
  71        merge is always that of the current branch head, effectively
  72        ignoring all changes from all other branches.  It is meant to
  73        be used to supersede old development history of side
  74        branches.  Note that this is different from the -Xours option to
  75        the 'recursive' merge strategy.
  76
  77subtree::
  78        This is a modified recursive strategy. When merging trees A and
  79        B, if B corresponds to a subtree of A, B is first adjusted to
  80        match the tree structure of A, instead of reading the trees at
  81        the same level. This adjustment is also done to the common
  82        ancestor tree.