Merge branch 'js/name-rev-use-oldest-ref' into maint

"git describe --contains" often made a hard-to-justify choice of
tag to give name to a given commit, because it tried to come up
with a name with smallest number of hops from a tag, causing an old
commit whose close descendant that is recently tagged were not
described with respect to an old tag but with a newer tag.  It did
not help that its computation of "hop" count was further tweaked to
penalize being on a side branch of a merge.  The logic has been
updated to favor using the tag with the oldest tagger date, which
is a lot easier to explain to the end users: "We describe a commit
in terms of the (chronologically) oldest tag that contains the
commit."

* js/name-rev-use-oldest-ref:
name-rev: include taggerdate in considering the best name

diff --git a/builtin/name-rev.c b/builtin/name-rev.c
index 092e03c3cc9b24445ee5ed92cee5b202e04c9ec7..57be35faf583d5bcb112c9f487b67ae4df8bf368 100644 (file)
--- a/builtin/name-rev.c
+++ b/builtin/name-rev.c
@@ -10,6 +10,7 @@
 
 typedef struct rev_name {
        const char *tip_name;
+       unsigned long taggerdate;
        int generation;
        int distance;
 } rev_name;
@@ -20,7 +21,8 @@ static long cutoff = LONG_MAX;
 #define MERGE_TRAVERSAL_WEIGHT 65535
 
 static void name_rev(struct commit *commit,
-               const char *tip_name, int generation, int distance,
+               const char *tip_name, unsigned long taggerdate,
+               int generation, int distance,
                int deref)
 {
        struct rev_name *name = (struct rev_name *)commit->util;
@@ -43,9 +45,12 @@ static void name_rev(struct commit *commit,
                name = xmalloc(sizeof(rev_name));
                commit->util = name;
                goto copy_data;
-       } else if (name->distance > distance) {
+       } else if (name->taggerdate > taggerdate ||
+                       (name->taggerdate == taggerdate &&
+                        name->distance > distance)) {
 copy_data:
                name->tip_name = tip_name;
+               name->taggerdate = taggerdate;
                name->generation = generation;
                name->distance = distance;
        } else
@@ -66,11 +71,11 @@ static void name_rev(struct commit *commit,
                                new_name = xstrfmt("%.*s^%d", (int)len, tip_name,
                                                   parent_number);
 
-                       name_rev(parents->item, new_name, 0,
+                       name_rev(parents->item, new_name, taggerdate, 0,
                                distance + MERGE_TRAVERSAL_WEIGHT, 0);
                } else {
-                       name_rev(parents->item, tip_name, generation + 1,
-                               distance + 1, 0);
+                       name_rev(parents->item, tip_name, taggerdate,
+                               generation + 1, distance + 1, 0);
                }
        }
 }
@@ -140,6 +145,7 @@ static int name_ref(const char *path, const struct object_id *oid, int flags, vo
        struct name_ref_data *data = cb_data;
        int can_abbreviate_output = data->tags_only && data->name_only;
        int deref = 0;
+       unsigned long taggerdate = ULONG_MAX;
 
        if (data->tags_only && !starts_with(path, "refs/tags/"))
                return 0;
@@ -164,12 +170,13 @@ static int name_ref(const char *path, const struct object_id *oid, int flags, vo
                        break; /* broken repository */
                o = parse_object(t->tagged->oid.hash);
                deref = 1;
+               taggerdate = t->date;
        }
        if (o && o->type == OBJ_COMMIT) {
                struct commit *commit = (struct commit *)o;
 
                path = name_ref_abbrev(path, can_abbreviate_output);
-               name_rev(commit, xstrdup(path), 0, 0, deref);
+               name_rev(commit, xstrdup(path), taggerdate, 0, 0, deref);
        }
        return 0;
 }

diff --git a/t/t9903-bash-prompt.sh b/t/t9903-bash-prompt.sh
index ffbfa0efb8712f06cb14adc986ae29c4d1c23bf1..0db4469c89492ae625307629cb7132178c3b9671 100755 (executable)
--- a/t/t9903-bash-prompt.sh
+++ b/t/t9903-bash-prompt.sh
@@ -107,7 +107,7 @@ test_expect_success 'prompt - describe detached head - contains' '
 '
 
 test_expect_success 'prompt - describe detached head - branch' '
-       printf " ((b1~1))" >expected &&
+       printf " ((tags/t2~1))" >expected &&
        git checkout b1^ &&
        test_when_finished "git checkout master" &&
        (