Merge branch 'jc/name-rev-lw-tag' into maint

"git describe --contains" penalized light-weight tags so much that
they were almost never considered.  Instead, give them about the
same chance to be considered as an annotated tag that is the same
age as the underlying commit would.

* jc/name-rev-lw-tag:
name-rev: favor describing with tags and use committer date to tiebreak
name-rev: refactor logic to see if a new candidate is a better name

diff --git a/builtin/name-rev.c b/builtin/name-rev.c
index e7a3fe7ee70759c34b9de12177078a55f27bfb9a..1767af750dde7f5184b4df25067f9f616c1918b3 100644 (file)
--- a/builtin/name-rev.c
+++ b/builtin/name-rev.c
@@ -13,6 +13,7 @@ typedef struct rev_name {
        unsigned long taggerdate;
        int generation;
        int distance;
+       int from_tag;
 } rev_name;
 
 static long cutoff = LONG_MAX;
@@ -20,9 +21,47 @@ static long cutoff = LONG_MAX;
 /* How many generations are maximally preferred over _one_ merge traversal? */
 #define MERGE_TRAVERSAL_WEIGHT 65535
 
+static int is_better_name(struct rev_name *name,
+                         const char *tip_name,
+                         unsigned long taggerdate,
+                         int generation,
+                         int distance,
+                         int from_tag)
+{
+       /*
+        * When comparing names based on tags, prefer names
+        * based on the older tag, even if it is farther away.
+        */
+       if (from_tag && name->from_tag)
+               return (name->taggerdate > taggerdate ||
+                       (name->taggerdate == taggerdate &&
+                        name->distance > distance));
+
+       /*
+        * We know that at least one of them is a non-tag at this point.
+        * favor a tag over a non-tag.
+        */
+       if (name->from_tag != from_tag)
+               return from_tag;
+
+       /*
+        * We are now looking at two non-tags.  Tiebreak to favor
+        * shorter hops.
+        */
+       if (name->distance != distance)
+               return name->distance > distance;
+
+       /* ... or tiebreak to favor older date */
+       if (name->taggerdate != taggerdate)
+               return name->taggerdate > taggerdate;
+
+       /* keep the current one if we cannot decide */
+       return 0;
+}
+
 static void name_rev(struct commit *commit,
                const char *tip_name, unsigned long taggerdate,
-               int generation, int distance,
+               int generation, int distance, int from_tag,
                int deref)
 {
        struct rev_name *name = (struct rev_name *)commit->util;
@@ -46,14 +85,14 @@ static void name_rev(struct commit *commit,
                name = xmalloc(sizeof(rev_name));
                commit->util = name;
                goto copy_data;
-       } else if (name->taggerdate > taggerdate ||
-                       (name->taggerdate == taggerdate &&
-                        name->distance > distance)) {
+       } else if (is_better_name(name, tip_name, taggerdate,
+                                 generation, distance, from_tag)) {
 copy_data:
                name->tip_name = tip_name;
                name->taggerdate = taggerdate;
                name->generation = generation;
                name->distance = distance;
+               name->from_tag = from_tag;
        } else {
                free(to_free);
                return;
@@ -75,10 +114,12 @@ static void name_rev(struct commit *commit,
                                                   parent_number);
 
                        name_rev(parents->item, new_name, taggerdate, 0,
-                               distance + MERGE_TRAVERSAL_WEIGHT, 0);
+                                distance + MERGE_TRAVERSAL_WEIGHT,
+                                from_tag, 0);
                } else {
                        name_rev(parents->item, tip_name, taggerdate,
-                               generation + 1, distance + 1, 0);
+                                generation + 1, distance + 1,
+                                from_tag, 0);
                }
        }
 }
@@ -209,9 +250,13 @@ static int name_ref(const char *path, const struct object_id *oid, int flags, vo
        }
        if (o && o->type == OBJ_COMMIT) {
                struct commit *commit = (struct commit *)o;
+               int from_tag = starts_with(path, "refs/tags/");
 
+               if (taggerdate == ULONG_MAX)
+                       taggerdate = ((struct commit *)o)->date;
                path = name_ref_abbrev(path, can_abbreviate_output);
-               name_rev(commit, xstrdup(path), taggerdate, 0, 0, deref);
+               name_rev(commit, xstrdup(path), taggerdate, 0, 0,
+                        from_tag, deref);
        }
        return 0;
 }

diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 1c7d6729c699dc8c8784d19659551df24530bd05..6499cdf6ff06b6da3185107f76902cc88767c15d 100755 (executable)
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -399,7 +399,7 @@ cat > expect <<\EOF
 | |
 | |     Merge branch 'side'
 | |
-| * commit side
+| * commit tags/side-2
 | | Author: A U Thor <author@example.com>
 | |
 | |     side-2