Merge branch 'mk/blame-first-parent'

"git blame" learnt to take "--first-parent" and "--reverse" at the
same time when it makes sense.

* mk/blame-first-parent:
blame: allow blame --reverse --first-parent when it makes sense
blame: extract find_single_final
blame: test to describe use of blame --reverse --first-parent

diff --git a/builtin/blame.c b/builtin/blame.c
index 3b80e8fd75cc0743035642cb82a284271925c865..83612f5b646f1db7232cf69cf5a2ea6b30a6e833 100644 (file)
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -2402,16 +2402,11 @@ static struct commit *fake_working_tree_commit(struct diff_options *opt,
        return commit;
 }
 
-static char *prepare_final(struct scoreboard *sb)
+static struct object_array_entry *find_single_final(struct rev_info *revs)
 {
        int i;
-       const char *final_commit_name = NULL;
-       struct rev_info *revs = sb->revs;
+       struct object_array_entry *found = NULL;
 
-       /*
-        * There must be one and only one positive commit in the
-        * revs->pending array.
-        */
        for (i = 0; i < revs->pending.nr; i++) {
                struct object *obj = revs->pending.objects[i].item;
                if (obj->flags & UNINTERESTING)
@@ -2420,14 +2415,24 @@ static char *prepare_final(struct scoreboard *sb)
                        obj = deref_tag(obj, NULL, 0);
                if (obj->type != OBJ_COMMIT)
                        die("Non commit %s?", revs->pending.objects[i].name);
-               if (sb->final)
+               if (found)
                        die("More than one commit to dig from %s and %s?",
                            revs->pending.objects[i].name,
-                           final_commit_name);
-               sb->final = (struct commit *) obj;
-               final_commit_name = revs->pending.objects[i].name;
+                           found->name);
+               found = &(revs->pending.objects[i]);
+       }
+       return found;
+}
+
+static char *prepare_final(struct scoreboard *sb)
+{
+       struct object_array_entry *found = find_single_final(sb->revs);
+       if (found) {
+               sb->final = (struct commit *) found->item;
+               return xstrdup(found->name);
+       } else {
+               return NULL;
        }
-       return xstrdup_or_null(final_commit_name);
 }
 
 static char *prepare_initial(struct scoreboard *sb)
@@ -2503,6 +2508,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        long dashdash_pos, lno;
        char *final_commit_name = NULL;
        enum object_type type;
+       struct commit *final_commit = NULL;
 
        static struct string_list range_list;
        static int output_option = 0, opt = 0;
@@ -2692,11 +2698,11 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        }
        else if (contents_from)
                die("--contents and --reverse do not blend well.");
-       else if (revs.first_parent_only)
-               die("combining --first-parent and --reverse is not supported");
        else {
                final_commit_name = prepare_initial(&sb);
                sb.commits.compare = compare_commits_by_reverse_commit_date;
+               if (revs.first_parent_only)
+                       revs.children.name = NULL;
        }
 
        if (!sb.final) {
@@ -2713,6 +2719,14 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        else if (contents_from)
                die("Cannot use --contents with final commit object name");
 
+       if (reverse && revs.first_parent_only) {
+               struct object_array_entry *entry = find_single_final(sb.revs);
+               if (!entry)
+                       die("--reverse and --first-parent together require specified latest commit");
+               else
+                       final_commit = (struct commit*) entry->item;
+       }
+
        /*
         * If we have bottom, this will mark the ancestors of the
         * bottom commits we would reach while traversing as
@@ -2721,6 +2735,25 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        if (prepare_revision_walk(&revs))
                die(_("revision walk setup failed"));
 
+       if (reverse && revs.first_parent_only) {
+               struct commit *c = final_commit;
+
+               sb.revs->children.name = "children";
+               while (c->parents &&
+                      hashcmp(c->object.sha1, sb.final->object.sha1)) {
+                       struct commit_list *l = xcalloc(1, sizeof(*l));
+
+                       l->item = c;
+                       if (add_decoration(&sb.revs->children,
+                                          &c->parents->item->object, l))
+                               die("BUG: not unique item in first-parent chain");
+                       c = c->parents->item;
+               }
+
+               if (hashcmp(c->object.sha1, sb.final->object.sha1))
+                       die("--reverse --first-parent together require range along first-parent chain");
+       }
+
        if (is_null_sha1(sb.final->object.sha1)) {
                o = sb.final->util;
                sb.final_buf = xmemdupz(o->file.ptr, o->file.size);

diff --git a/t/t8009-blame-vs-topicbranches.sh b/t/t8009-blame-vs-topicbranches.sh
new file mode 100755 (executable)
index 0000000..72596e3
--- /dev/null
+++ b/t/t8009-blame-vs-topicbranches.sh
@@ -0,0 +1,36 @@
+#!/bin/sh
+
+test_description='blaming trough history with topic branches'
+. ./test-lib.sh
+
+# Creates the history shown below. '*'s mark the first parent in the merges.
+# The only line of file.t is changed in commit B2
+#
+#        +---C1
+#       /      \
+# A0--A1--*A2--*A3
+#   \     /
+#    B1-B2
+#
+test_expect_success setup '
+       test_commit A0 file.t line0 &&
+       test_commit A1 &&
+       git reset --hard A0 &&
+       test_commit B1 &&
+       test_commit B2 file.t line0changed &&
+       git reset --hard A1 &&
+       test_merge A2 B2 &&
+       git reset --hard A1 &&
+       test_commit C1 &&
+       git reset --hard A2 &&
+       test_merge A3 C1
+       '
+
+test_expect_success 'blame --reverse --first-parent finds A1' '
+       git blame --porcelain --reverse --first-parent A0..A3 -- file.t >actual_full &&
+       head -n 1 <actual_full | sed -e "s/ .*//" >actual &&
+       git rev-parse A1 >expect &&
+       test_cmp expect actual
+       '
+
+test_done