Re: git-rev-list: add "--dense" flag

[Linus Torvalds <torvalds@osdl.org>]

On Tue, 25 Oct 2005, Jonas Fonseca wrote:
> 
> Is the initial commit supposed to be listed when the file has been added
> later?

Right now --dense will _always_ show the root commit. I didn't do the 
logic that does the diff against an empty tree. I was lazy.

This patch does that, and may or may not work.

Does this match what you expected?

		Linus

----
diff --git a/rev-list.c b/rev-list.c
index 5f125fd..038dae2 100644
--- a/rev-list.c
+++ b/rev-list.c
@@ -439,6 +439,30 @@ static int same_tree(struct tree *t1, st
 	return !is_different;
 }
 
+static int same_tree_as_empty(struct tree *t1)
+{
+	int retval;
+	void *tree;
+	struct tree_desc empty, real;
+
+	if (!t1)
+		return 0;
+
+	tree = read_object_with_reference(t1->object.sha1, "tree", &real.size, NULL);
+	if (!tree)
+		return 0;
+	real.buf = tree;
+
+	empty.buf = "";
+	empty.size = 0;
+
+	is_different = 0;
+	retval = diff_tree(&empty, &real, "", &diff_opt);
+	free(tree);
+
+	return !retval && !is_different;
+}
+
 static struct commit *try_to_simplify_merge(struct commit *commit, struct commit_list *parent)
 {
 	if (!commit->tree)
@@ -523,11 +547,17 @@ static void compress_list(struct commit_
 		struct commit_list *parent = commit->parents;
 		list = list->next;
 
+		if (!parent) {
+			if (!same_tree_as_empty(commit->tree))
+				commit->object.flags |= TREECHANGE;
+			continue;
+		}
+
 		/*
 		 * Exactly one parent? Check if it leaves the tree
 		 * unchanged
 		 */
-		if (parent && !parent->next) {
+		if (!parent->next) {
 			struct tree *t1 = commit->tree;
 			struct tree *t2 = parent->item->tree;
 			if (!t1 || !t2 || same_tree(t1, t2))