ref-filter: add --no-contains option to tag/branch/for-each-ref

Change the tag, branch & for-each-ref commands to have a --no-contains
option in addition to their longstanding --contains options.

This allows for finding the last-good rollout tag given a known-bad
<commit>. Given a hypothetically bad commit cf5c7253e0, the git
version to revert to can be found with this hacky two-liner:

    (git tag -l 'v[0-9]*'; git tag -l --contains cf5c7253e0 'v[0-9]*') |
        sort | uniq -c | grep -E '^ *1 ' | awk '{print $2}' | tail -n 10

With this new --no-contains option the same can be achieved with:

    git tag -l --no-contains cf5c7253e0 'v[0-9]*' | sort | tail -n 10

As the filtering machinery is shared between the tag, branch &
for-each-ref commands, implement this for those commands too. A
practical use for this with "branch" is e.g. finding branches which
were branched off between v2.8.0 and v2.10.0:

    git branch --contains v2.8.0 --no-contains v2.10.0

The "describe" command also has a --contains option, but its semantics
are unrelated to what tag/branch/for-each-ref use --contains for. A
--no-contains option for "describe" wouldn't make any sense, other
than being exactly equivalent to not supplying --contains at all,
which would be confusing at best.

Add a --without option to "tag" as an alias for --no-contains, for
consistency with --with and --contains.  The --with option is
undocumented, and possibly the only user of it is
Junio (<xmqqefy71iej.fsf@gitster.mtv.corp.google.com>). But it's
trivial to support, so let's do that.

The additions to the the test suite are inverse copies of the
corresponding --contains tests. With this change --no-contains for
tag, branch & for-each-ref is just as well tested as the existing
--contains option.

In addition to those tests, add a test for "tag" which asserts that
--no-contains won't find tree/blob tags, which is slightly
unintuitive, but consistent with how --contains works & is documented.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/ref-filter.c b/ref-filter.c
index 81da37b..71b72e0 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1487,6 +1487,7 @@ struct ref_filter_cbdata {
 	struct ref_array *array;
 	struct ref_filter *filter;
 	struct contains_cache contains_cache;
+	struct contains_cache no_contains_cache;
 };
 
 /*
@@ -1586,11 +1587,11 @@ static enum contains_result contains_tag_algo(struct commit *candidate,
 }
 
 static int commit_contains(struct ref_filter *filter, struct commit *commit,
-			   struct contains_cache *cache)
+			   struct commit_list *list, struct contains_cache *cache)
 {
 	if (filter->with_commit_tag_algo)
-		return contains_tag_algo(commit, filter->with_commit, cache) == CONTAINS_YES;
-	return is_descendant_of(commit, filter->with_commit);
+		return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
+	return is_descendant_of(commit, list);
 }
 
 /*
@@ -1780,13 +1781,17 @@ static int ref_filter_handler(const char *refname, const struct object_id *oid,
 	 * obtain the commit using the 'oid' available and discard all
 	 * non-commits early. The actual filtering is done later.
 	 */
-	if (filter->merge_commit || filter->with_commit || filter->verbose) {
+	if (filter->merge_commit || filter->with_commit || filter->no_commit || filter->verbose) {
 		commit = lookup_commit_reference_gently(oid->hash, 1);
 		if (!commit)
 			return 0;
-		/* We perform the filtering for the '--contains' option */
+		/* We perform the filtering for the '--contains' option... */
 		if (filter->with_commit &&
-		    !commit_contains(filter, commit, &ref_cbdata->contains_cache))
+		    !commit_contains(filter, commit, filter->with_commit, &ref_cbdata->contains_cache))
+			return 0;
+		/* ...or for the `--no-contains' option */
+		if (filter->no_commit &&
+		    commit_contains(filter, commit, filter->no_commit, &ref_cbdata->no_contains_cache))
 			return 0;
 	}
 
@@ -1887,6 +1892,7 @@ int filter_refs(struct ref_array *array, struct ref_filter *filter, unsigned int
 	filter->kind = type & FILTER_REFS_KIND_MASK;
 
 	init_contains_cache(&ref_cbdata.contains_cache);
+	init_contains_cache(&ref_cbdata.no_contains_cache);
 
 	/*  Simple per-ref filtering */
 	if (!filter->kind)
@@ -1911,6 +1917,7 @@ int filter_refs(struct ref_array *array, struct ref_filter *filter, unsigned int
 	}
 
 	clear_contains_cache(&ref_cbdata.contains_cache);
+	clear_contains_cache(&ref_cbdata.no_contains_cache);
 
 	/*  Filters that need revision walking */
 	if (filter->merge_commit)