bisect: limit the searchspace by pathspecs

It was surprisingly easy to do.

	git bisect start <pathspec>

followed by all the normal "git bisect good/bad" stuff.

Almost totally untested, and I guarantee that if your pathnames have
spaces in them (or your GIT_DIR has spaces in it) this won't work. I don't
know how to fix that, my shell programming isn't good enough.

This involves small changes to make "git-rev-list --bisect" work in the
presense of a pathspec limiter, and then truly trivial (and that's the
broken part) changes to make "git bisect" save away and use the pathspec.

I tried one bisection, and a "git bisect visualize", and it all looked
correct. But hey, don't be surprised if it has problems.

		Linus

Signed-off-by: Junio C Hamano <junkio@cox.net>

git-bisect.sh

@@ -33,7 +33,6 @@ bisect_autostart() {
 }
 
 bisect_start() {
-        case "$#" in 0) ;; *) usage ;; esac
 	#
 	# Verify HEAD. If we were bisecting before this, reset to the
 	# top-of-line master first!
@@ -57,7 +56,8 @@ bisect_start() {
 	rm -f "$GIT_DIR/refs/heads/bisect"
 	rm -rf "$GIT_DIR/refs/bisect/"
 	mkdir "$GIT_DIR/refs/bisect"
-	echo "git-bisect start" >"$GIT_DIR/BISECT_LOG"
+	echo "git-bisect start $@" >"$GIT_DIR/BISECT_LOG"
+	echo "$@" > "$GIT_DIR/BISECT_NAMES"
 }
 
 bisect_bad() {
@@ -121,7 +121,7 @@ bisect_next() {
 	bad=$(git-rev-parse --verify refs/bisect/bad) &&
 	good=$(git-rev-parse --sq --revs-only --not \
 		$(cd "$GIT_DIR" && ls refs/bisect/good-*)) &&
-	rev=$(eval "git-rev-list --bisect $good $bad") || exit
+	rev=$(eval "git-rev-list --bisect $good $bad -- $(cat $GIT_DIR/BISECT_NAMES)") || exit
 	if [ -z "$rev" ]; then
 	    echo "$bad was both good and bad"
 	    exit 1
@@ -131,7 +131,7 @@ bisect_next() {
 	    git-diff-tree --pretty $rev
 	    exit 0
 	fi
-	nr=$(eval "git-rev-list $rev $good" | wc -l) || exit
+	nr=$(eval "git-rev-list $rev $good -- $(cat $GIT_DIR/BISECT_NAMES)" | wc -l) || exit
 	echo "Bisecting: $nr revisions left to test after this"
 	echo "$rev" > "$GIT_DIR/refs/heads/new-bisect"
 	git checkout new-bisect || exit
@@ -142,7 +142,7 @@ bisect_next() {
 
 bisect_visualize() {
 	bisect_next_check fail
-	gitk bisect/bad --not `cd "$GIT_DIR/refs" && echo bisect/good-*`
+	gitk bisect/bad --not `cd "$GIT_DIR/refs" && echo bisect/good-*` -- $(cat $GIT_DIR/BISECT_NAMES)
 }
 
 bisect_reset() {

rev-list.c

@@ -350,7 +350,8 @@ static int count_distance(struct commit_list *entry)
 
 		if (commit->object.flags & (UNINTERESTING | COUNTED))
 			break;
-		nr++;
+		if (!paths || (commit->object.flags & TREECHANGE))
+			nr++;
 		commit->object.flags |= COUNTED;
 		p = commit->parents;
 		entry = p;
@@ -362,6 +363,7 @@ static int count_distance(struct commit_list *entry)
 			}
 		}
 	}
+
 	return nr;
 }
 
@@ -382,15 +384,20 @@ static struct commit_list *find_bisection(struct commit_list *list)
 	nr = 0;
 	p = list;
 	while (p) {
-		nr++;
+		if (!paths || (p->item->object.flags & TREECHANGE))
+			nr++;
 		p = p->next;
 	}
 	closest = 0;
 	best = list;
 
-	p = list;
-	while (p) {
-		int distance = count_distance(p);
+	for (p = list; p; p = p->next) {
+		int distance;
+
+		if (paths && !(p->item->object.flags & TREECHANGE))
+			continue;
+
+		distance = count_distance(p);
 		clear_distance(list);
 		if (nr - distance < distance)
 			distance = nr - distance;
@@ -398,7 +405,6 @@ static struct commit_list *find_bisection(struct commit_list *list)
 			best = p;
 			closest = distance;
 		}
-		p = p->next;
 	}
 	if (best)
 		best->next = NULL;