describe: Add --first-parent option

Only consider the first parent commit when walking the commit history. This
is useful if you only wish to match tags on your branch after a merge.

Signed-off-by: Mike Crowe <mac@mcrowe.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-describe.txt b/Documentation/git-describe.txt
index 28e5ec0e2c1466f37e1e91680fb438658e050102..9439cd6d56b0d3aa2115b9843936b449b6765652 100644 (file)
--- a/Documentation/git-describe.txt
+++ b/Documentation/git-describe.txt
@@ -88,6 +88,11 @@ OPTIONS
 --always::
        Show uniquely abbreviated commit object as fallback.
 
+--first-parent::
+       Follow only the first parent commit upon seeing a merge commit.
+       This is useful when you wish to not match tags on branches merged
+       in the history of the target commit.
+
 EXAMPLES
 --------
 
@@ -149,7 +154,9 @@ is found, its name will be output and searching will stop.
 If an exact match was not found, 'git describe' will walk back
 through the commit history to locate an ancestor commit which
 has been tagged.  The ancestor's tag will be output along with an
-abbreviation of the input committish's SHA-1.
+abbreviation of the input committish's SHA-1. If '--first-parent' was
+specified then the walk will only consider the first parent of each
+commit.
 
 If multiple tags were found during the walk then the tag which
 has the fewest commits different from the input committish will be

diff --git a/builtin/describe.c b/builtin/describe.c
index 6636a68cd919ba227a10cfa39efcd5f4e77a801d..ad8471626ac4c6f4f4eda413114665fb4fcca018 100644 (file)
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -21,6 +21,7 @@ static int debug;     /* Display lots of verbose info */
 static int all;        /* Any valid ref can be used */
 static int tags;       /* Allow lightweight tags */
 static int longformat;
+static int first_parent;
 static int abbrev = -1; /* unspecified */
 static int max_candidates = 10;
 static struct hash_table names;
@@ -336,6 +337,9 @@ static void describe(const char *arg, int last_one)
                                commit_list_insert_by_date(p, &list);
                        p->object.flags |= c->object.flags;
                        parents = parents->next;
+
+                       if (first_parent)
+                               break;
                }
        }
 
@@ -404,6 +408,7 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
                OPT_BOOLEAN(0, "all",        &all, N_("use any ref")),
                OPT_BOOLEAN(0, "tags",       &tags, N_("use any tag, even unannotated")),
                OPT_BOOLEAN(0, "long",       &longformat, N_("always use long format")),
+               OPT_BOOLEAN(0, "first-parent", &first_parent, N_("only follow first parent")),
                OPT__ABBREV(&abbrev),
                OPT_SET_INT(0, "exact-match", &max_candidates,
                            N_("only output exact matches"), 0),

diff --git a/t/t6120-describe.sh b/t/t6120-describe.sh
index f67aa6ff6a3c2af2d0c1999e8203da3a922b0555..a25729f2a7bb4c4d4f755ef5f855261ee1d71645 100755 (executable)
--- a/t/t6120-describe.sh
+++ b/t/t6120-describe.sh
@@ -110,6 +110,9 @@ check_describe tags/e --all HEAD^^^
 check_describe B-0-* --long HEAD^^2^
 check_describe A-3-* --long HEAD^^2
 
+check_describe c-7-* --tags
+check_describe e-3-* --first-parent --tags
+
 : >err.expect
 check_describe A --all A^0
 test_expect_success 'no warning was displayed for A' '