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Diffstat (limited to 'Documentation/merge-strategies.txt')
| -rw-r--r-- | Documentation/merge-strategies.txt | 111 |
1 files changed, 100 insertions, 11 deletions
diff --git a/Documentation/merge-strategies.txt b/Documentation/merge-strategies.txt index 1276f858ad..2eb92b9327 100644 --- a/Documentation/merge-strategies.txt +++ b/Documentation/merge-strategies.txt @@ -1,38 +1,119 @@ 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 3-way merge + 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 3-way merge - algorithm. When there are more than one common - ancestors that can be used for 3-way merge, it creates a + 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 + causing mismerges 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. + 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'. + +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`. + +diff-algorithm=[patience|minimal|histogram|myers];; + Tells 'merge-recursive' to use a different diff algorithm, which + can help avoid mismerges that occur due to unimportant matching + lines (such as braces from distinct functions). See also + linkgit:git-diff[1] `--diff-algorithm`. + +ignore-space-change;; +ignore-all-space;; +ignore-space-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 linkgit:git-diff[1] `-b`, `-w`, and + `--ignore-space-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 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. + +no-renames;; + Turn off rename detection. + See also linkgit:git-diff[1] `--no-renames`. + +find-renames[=<n>];; + Turn on rename detection, optionally setting the similarity + threshold. This is the default. + See also linkgit:git-diff[1] `--find-renames`. + +rename-threshold=<n>;; + Deprecated synonym for `find-renames=<n>`. + +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 more than two-head case, but refuses to do - complex merge that needs manual resolution. It is + 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 branches. + pulling or merging more than one branch. ours:: - This resolves any number of heads, but the result of the - merge is always the current branch head. It is meant to + 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. + 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 @@ -40,3 +121,11 @@ subtree:: 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, 'recursive'), +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. |