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-rw-r--r--Documentation/git-merge-base.txt34
1 files changed, 21 insertions, 13 deletions
diff --git a/Documentation/git-merge-base.txt b/Documentation/git-merge-base.txt
index ba36ec04f4..b295bf8330 100644
--- a/Documentation/git-merge-base.txt
+++ b/Documentation/git-merge-base.txt
@@ -9,7 +9,8 @@ git-merge-base - Find as good common ancestors as possible for a merge
SYNOPSIS
--------
[verse]
-'git merge-base' [-a|--all] [--octopus] <commit> <commit>...
+'git merge-base' [-a|--all] <commit> <commit>...
+'git merge-base' [-a|--all] --octopus <commit>...
'git merge-base' --independent <commit>...
DESCRIPTION
@@ -22,23 +23,21 @@ that does not have any better common ancestor is a 'best common
ancestor', i.e. a 'merge base'. Note that there can be more than one
merge base for a pair of commits.
-Unless `--octopus` is given, among the two commits to compute the merge
-base from, one is specified by the first commit argument on the command
-line; the other commit is a (possibly hypothetical) commit that is a merge
-across all the remaining commits on the command line. As the most common
-special case, specifying only two commits on the command line means
-computing the merge base between the given two commits.
+OPERATION MODE
+--------------
+
+As the most common special case, specifying only two commits on the
+command line means computing the merge base between the given two commits.
+
+More generally, among the two commits to compute the merge base from,
+one is specified by the first commit argument on the command line;
+the other commit is a (possibly hypothetical) commit that is a merge
+across all the remaining commits on the command line.
As a consequence, the 'merge base' is not necessarily contained in each of the
commit arguments if more than two commits are specified. This is different
from linkgit:git-show-branch[1] when used with the `--merge-base` option.
-OPTIONS
--------
--a::
---all::
- Output all merge bases for the commits, instead of just one.
-
--octopus::
Compute the best common ancestors of all supplied commits,
in preparation for an n-way merge. This mimics the behavior
@@ -51,6 +50,12 @@ OPTIONS
from any other. This mimics the behavior of 'git show-branch
--independent'.
+OPTIONS
+-------
+-a::
+--all::
+ Output all merge bases for the commits, instead of just one.
+
DISCUSSION
----------
@@ -89,6 +94,9 @@ and the result of `git merge-base A M` is '1'. Commit '2' is also a
common ancestor between 'A' and 'M', but '1' is a better common ancestor,
because '2' is an ancestor of '1'. Hence, '2' is not a merge base.
+The result of `git merge-base --octopus A B C` is '2', because '2' is
+the best common ancestor of all commits.
+
When the history involves criss-cross merges, there can be more than one
'best' common ancestor for two commits. For example, with this topology: