CLJS-1201 Empty Vectors and Subvecs throw on comparison

Author: tonsky

src/cljs/cljs/core.cljs

@@ -1938,6 +1938,7 @@ reduces them without incurring seq initialization"
        (cond
         (< xl yl) -1
         (> xl yl) 1
+        (== xl 0) 0
         :else (compare-indexed xs ys xl 0))))
   ([xs ys len n]
      (let [d (compare (nth xs n) (nth ys n))]

test/cljs/cljs/core_test.cljs

@@ -1679,18 +1679,23 @@
     (is (=  1 (compare [1 2] [1 1])))
     (is (=  1 (compare [1 1 1] [1 2])))
     (is (=  1 (compare [1 1 2] [1 1 1])))
+    (is (=  0 (compare [] [])))
+    (is (=  0 (compare (vec #js []) [])))
+    (is (=  0 (compare (with-meta [] {}) [])))
+    (is (=  0 (compare (pop [1]) [])))
 
     (is (= -1 (compare (subvec [1 2 3] 1) (subvec [1 2 4] 1))))
     (is (=  0 (compare (subvec [1 2 3] 1) (subvec [1 2 3] 1))))
-    (is (=  1 (compare (subvec [1 2 4] 1) (subvec [1 2 3] 1)))))
+    (is (=  1 (compare (subvec [1 2 4] 1) (subvec [1 2 3] 1))))
+    (is (=  0 (compare (subvec [1] 0 0) (subvec [2] 0 0))))
 
     (is (=  0 (compare (js/Date. 2015 2 8 19 13 00 999)
                        (js/Date. 2015 2 8 19 13 00 999))))
     (is (= -1 (compare (js/Date. 2015 2 8 19 12 00 999)
                        (js/Date. 2015 2 8 19 13 00 999))))
     (is (=  1 (compare (js/Date. 2015 2 8 19 14 00 999)
                        (js/Date. 2015 2 8 19 13 00 999))))
-  )
+  ))
 
 (deftest test-dot
   (let [s "abc"]