While show-branch --merge-base does not support more than MAX_REVS
revs, git supports more with a different algorithm
(v1.6.0-rc0~51^2~13, Introduce get_octopus_merge_bases() in commit.c,
2008-06-27). Expose that functionality.
This should help scripts to catch up with builtin merge in supporting
dodecapus.
Signed-off-by: Jonathan Nieder <jrnieder@xxxxxxxxx>
---
Documentation/git-merge-base.txt | 19 ++++++++++++-------
builtin/merge-base.c | 35 ++++++++++++++++++++++++++++++++---
t/t6010-merge-base.sh | 2 ++
3 files changed, 46 insertions(+), 10 deletions(-)
diff --git a/Documentation/git-merge-base.txt b/Documentation/git-merge-base.txt
index 09b34b0..125207e 100644
--- a/Documentation/git-merge-base.txt
+++ b/Documentation/git-merge-base.txt
@@ -8,7 +8,7 @@ git-merge-base - Find as good common ancestors as possible for a merge
SYNOPSIS
--------
-'git merge-base' [-a|--all] <commit> <commit>...
+'git merge-base' [-a|--all] [--octopus] <commit> <commit>...
DESCRIPTION
-----------
@@ -20,12 +20,12 @@ 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.
-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.
+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.
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
@@ -37,6 +37,11 @@ OPTIONS
--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
+ of 'git show-branch --merge-base'.
+
DISCUSSION
----------
diff --git a/builtin/merge-base.c b/builtin/merge-base.c
index 54e7ec2..c301286 100644
--- a/builtin/merge-base.c
+++ b/builtin/merge-base.c
@@ -23,7 +23,7 @@ static int show_merge_base(struct commit **rev, int rev_nr, int show_all)
}
static const char * const merge_base_usage[] = {
- "git merge-base [-a|--all] <commit> <commit>...",
+ "git merge-base [-a|--all] [--octopus] <commit> <commit>...",
NULL
};
@@ -41,21 +41,50 @@ static struct commit *get_commit_reference(const char *arg)
return r;
}
+static int show_octopus_merge_bases(int count, const char **args, int show_all)
+{
+ struct commit_list *revs = NULL;
+ struct commit_list *result;
+ int i;
+
+ for (i = count - 1; i >= 0; i++)
+ commit_list_insert(get_commit_reference(args[i]), &revs);
+ result = get_octopus_merge_bases(revs);
+
+ if (!result)
+ return 1;
+
+ while (result) {
+ printf("%s\n", sha1_to_hex(result->item->object.sha1));
+ if (!show_all)
+ return 0;
+ result = result->next;
+ }
+
+ return 0;
+}
+
int cmd_merge_base(int argc, const char **argv, const char *prefix)
{
struct commit **rev;
int rev_nr = 0;
int show_all = 0;
+ int octopus = 0;
struct option options[] = {
- OPT_BOOLEAN('a', "all", &show_all, "outputs all common ancestors"),
+ OPT_BOOLEAN('a', "all", &show_all, "output all common ancestors"),
+ OPT_BOOLEAN(0, "octopus", &octopus, "find ancestors for a single n-way merge"),
OPT_END()
};
git_config(git_default_config, NULL);
argc = parse_options(argc, argv, prefix, options, merge_base_usage, 0);
- if (argc < 2)
+ if (!octopus && argc < 2)
usage_with_options(merge_base_usage, options);
+
+ if (octopus)
+ return show_octopus_merge_bases(argc, argv, show_all);
+
rev = xmalloc(argc * sizeof(*rev));
while (argc-- > 0)
rev[rev_nr++] = get_commit_reference(*argv++);
diff --git a/t/t6010-merge-base.sh b/t/t6010-merge-base.sh
index 4466e45..001431b 100755
--- a/t/t6010-merge-base.sh
+++ b/t/t6010-merge-base.sh
@@ -164,9 +164,11 @@ test_expect_success 'merge-base A B C' '
git rev-parse --verify MMR >expected.sb &&
git merge-base --all MMA MMB MMC >actual &&
+ git merge-base --all --octopus MMA MMB MMC >actual.common &&
git show-branch --merge-base MMA MMB MMC >actual.sb &&
test_cmp expected actual &&
+ test_cmp expected.sb actual.common &&
test_cmp expected.sb actual.sb
'
--
1.7.2.1.544.ga752d.dirty
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