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 mismerges 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 For a binary file, the entire contents are taken from our side. 36+ 37This should not be confused with the 'ours' merge strategy, which does not 38even look at what the other tree contains at all. It discards everything 39the other tree did, declaring 'our' history contains all that happened in it. 40 41theirs;; 42 This is the opposite of 'ours'. 43 44patience;; 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 51diff-algorithm=[patience|minimal|histogram|myers];; 52 Tells 'merge-recursive' to use a different diff algorithm, which 53 can help avoid mismerges that occur due to unimportant matching 54 lines (such as braces from distinct functions). See also 55 linkgit:git-diff[1] `--diff-algorithm`. 56 57ignore-space-change;; 58ignore-all-space;; 59ignore-space-at-eol;; 60 Treats lines with the indicated type of whitespace change as 61 unchanged for the sake of a three-way merge. Whitespace 62 changes mixed with other changes to a line are not ignored. 63 See also linkgit:git-diff[1] `-b`, `-w`, and 64 `--ignore-space-at-eol`. 65+ 66* If 'their' version only introduces whitespace changes to a line, 67 'our' version is used; 68* If 'our' version introduces whitespace changes but 'their' 69 version includes a substantial change, 'their' version is used; 70* Otherwise, the merge proceeds in the usual way. 71 72renormalize;; 73 This runs a virtual check-out and check-in of all three stages 74 of a file when resolving a three-way merge. This option is 75 meant to be used when merging branches with different clean 76 filters or end-of-line normalization rules. See "Merging 77 branches with differing checkin/checkout attributes" in 78 linkgit:gitattributes[5] for details. 79 80no-renormalize;; 81 Disables the `renormalize` option. This overrides the 82 `merge.renormalize` configuration variable. 83 84rename-threshold=<n>;; 85 Controls the similarity threshold used for rename detection. 86 See also linkgit:git-diff[1] `-M`. 87 88subtree[=<path>];; 89 This option is a more advanced form of 'subtree' strategy, where 90 the strategy makes a guess on how two trees must be shifted to 91 match with each other when merging. Instead, the specified path 92 is prefixed (or stripped from the beginning) to make the shape of 93 two trees to match. 94 95octopus:: 96 This resolves cases with more than two heads, but refuses to do 97 a complex merge that needs manual resolution. It is 98 primarily meant to be used for bundling topic branch 99 heads together. This is the default merge strategy when 100 pulling or merging more than one branch. 101 102ours:: 103 This resolves any number of heads, but the resulting tree of the 104 merge is always that of the current branch head, effectively 105 ignoring all changes from all other branches. It is meant to 106 be used to supersede old development history of side 107 branches. Note that this is different from the -Xours option to 108 the 'recursive' merge strategy. 109 110subtree:: 111 This is a modified recursive strategy. When merging trees A and 112 B, if B corresponds to a subtree of A, B is first adjusted to 113 match the tree structure of A, instead of reading the trees at 114 the same level. This adjustment is also done to the common 115 ancestor tree. 116 117With the strategies that use 3-way merge (including the default, 'recursive'), 118if a change is made on both branches, but later reverted on one of the 119branches, that change will be present in the merged result; some people find 120this behavior confusing. It occurs because only the heads and the merge base 121are considered when performing a merge, not the individual commits. The merge 122algorithm therefore considers the reverted change as no change at all, and 123substitutes the changed version instead.