2 files changed, 8 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog
index 924dd9fc74..0dae1fb099 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Oct 26 20:04:13 2009  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
+
+	* array.c (rb_ary_cmp): Array#<=> returns nil when comparison fails
+	  [ruby-core:26316]
+
 Mon Oct 26 18:37:57 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* hash.c (default_proc_arity_check): new support function.
diff --git a/array.c b/array.c
index 05d5494af7..f1927d265a 100644
--- a/array.c
+++ b/array.c
@@ -2963,7 +2963,7 @@ recursive_cmp(VALUE ary1, VALUE ary2, int recur)
 
 /*
  *  call-seq:
- *     array <=> other_array   ->  -1, 0, +1
+ *     array <=> other_array   ->  -1, 0, +1, nil
  *
  *  Comparison---Returns an integer (-1, 0,
  *  or +1) if this array is less than, equal to, or greater than
@@ -2987,7 +2987,8 @@ rb_ary_cmp(VALUE ary1, VALUE ary2)
     long len;
     VALUE v;
 
-    ary2 = to_ary(ary2);
+    ary2 = rb_check_array_type(ary2);
+    if (NIL_P(ary2)) return Qnil;
     if (ary1 == ary2) return INT2FIX(0);
     v = rb_exec_recursive_paired(recursive_cmp, ary1, ary2, ary2);
     if (v != Qundef) return v;