merge-base --octopus to mimic show-branch --merge-base
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@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jonathan Nieder committed
Aug 17, 2010 at 02:01 UTC
aa8f98c1bfcf162e0bd23d20c34857940f2c2256
3 files changed
+46
-10
Documentation/git-merge-base.txt
+12
-7
@@ -8,7 +8,7 @@ git-merge-base - Find as good common ancestors as possible for a merge
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SYNOPSIS
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--------
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-'git merge-base' [-a|--all] <commit> <commit>...
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+'git merge-base' [-a|--all] [--octopus] <commit> <commit>...
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DESCRIPTION
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-----------
@@ -20,12 +20,12 @@ that does not have any better common ancestor is a 'best common
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ancestor', i.e. a 'merge base'. Note that there can be more than one
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merge base for a pair of commits.
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-Among the two commits to compute the merge base from, one is specified by
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-the first commit argument on the command line; the other commit is a
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-(possibly hypothetical) commit that is a merge across all the remaining
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-commits on the command line. As the most common special case, specifying only
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-two commits on the command line means computing the merge base between
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-the given two commits.
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+Unless `--octopus` is given, among the two commits to compute the merge
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+base from, one is specified by the first commit argument on the command
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+line; the other commit is a (possibly hypothetical) commit that is a merge
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+across all the remaining commits on the command line. As the most common
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+special case, specifying only two commits on the command line means
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+computing the merge base between the given two commits.
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As a consequence, the 'merge base' is not necessarily contained in each of the
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commit arguments if more than two commits are specified. This is different
@@ -37,6 +37,11 @@ OPTIONS
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--all::
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Output all merge bases for the commits, instead of just one.
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+--octopus::
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+ Compute the best common ancestors of all supplied commits,
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+ in preparation for an n-way merge. This mimics the behavior
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+ of 'git show-branch --merge-base'.
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+
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DISCUSSION
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----------
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builtin/merge-base.c
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-3
@@ -23,7 +23,7 @@ static int show_merge_base(struct commit **rev, int rev_nr, int show_all)
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}
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static const char * const merge_base_usage[] = {
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- "git merge-base [-a|--all] <commit> <commit>...",
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+ "git merge-base [-a|--all] [--octopus] <commit> <commit>...",
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NULL
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};
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@@ -41,21 +41,50 @@ static struct commit *get_commit_reference(const char *arg)
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return r;
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}
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+static int show_octopus_merge_bases(int count, const char **args, int show_all)
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+{
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+ struct commit_list *revs = NULL;
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+ struct commit_list *result;
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+ int i;
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+
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+ for (i = count - 1; i >= 0; i++)
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+ commit_list_insert(get_commit_reference(args[i]), &revs);
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+ result = get_octopus_merge_bases(revs);
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+
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+ if (!result)
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+ return 1;
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+
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+ while (result) {
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+ printf("%s\n", sha1_to_hex(result->item->object.sha1));
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+ if (!show_all)
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+ return 0;
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+ result = result->next;
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+ }
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+
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+ return 0;
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+}
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+
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int cmd_merge_base(int argc, const char **argv, const char *prefix)
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{
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struct commit **rev;
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int rev_nr = 0;
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int show_all = 0;
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+ int octopus = 0;
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struct option options[] = {
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- OPT_BOOLEAN('a', "all", &show_all, "outputs all common ancestors"),
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+ OPT_BOOLEAN('a', "all", &show_all, "output all common ancestors"),
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+ OPT_BOOLEAN(0, "octopus", &octopus, "find ancestors for a single n-way merge"),
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OPT_END()
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};
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git_config(git_default_config, NULL);
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argc = parse_options(argc, argv, prefix, options, merge_base_usage, 0);
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- if (argc < 2)
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+ if (!octopus && argc < 2)
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usage_with_options(merge_base_usage, options);
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+
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+ if (octopus)
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+ return show_octopus_merge_bases(argc, argv, show_all);
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+
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rev = xmalloc(argc * sizeof(*rev));
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while (argc-- > 0)
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rev[rev_nr++] = get_commit_reference(*argv++);
t/t6010-merge-base.sh
+2
@@ -164,9 +164,11 @@ test_expect_success 'merge-base A B C' '
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git rev-parse --verify MMR >expected.sb &&
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git merge-base --all MMA MMB MMC >actual &&
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+ git merge-base --all --octopus MMA MMB MMC >actual.common &&
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git show-branch --merge-base MMA MMB MMC >actual.sb &&
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test_cmp expected actual &&
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+ test_cmp expected.sb actual.common &&
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test_cmp expected.sb actual.sb
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'
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