Update to Java commit 8f46135 (2024.05.08): CLJ-2717 nthrest does not return a rest output on n=0 or past end of seq

Author: dmiller

Clojure/Clojure.Source/clojure/core.clj

@@ -3188,14 +3188,16 @@
   {:added "1.3"
    :static true}
   [coll n]
-  (if (instance? clojure.lang.IDrop coll)
-    (if (pos? n)
-          (or (.drop ^clojure.lang.IDrop coll (if (int? n) n (Math/Ceiling (. clojure.lang.RT (doubleCast n))))) ())     ;;; Math/ceil -- added doubleCast
-      coll)
-    (loop [n n xs coll]
-      (if-let [xs (and (pos? n) (seq xs))]
-        (recur (dec n) (rest xs))
-        xs))))
+  (if (pos? n)
+    (or
+      (if (instance? clojure.lang.IDrop coll)
+        (.drop ^clojure.lang.IDrop coll (if (int? n) n (Math/Ceiling (. clojure.lang.RT (doubleCast n)))))     ;;; Math/ceil -- added doubleCast
+        (loop [n n xs coll]
+          (if-let [xs (and (pos? n) (seq xs))]
+            (recur (dec n) (rest xs))
+            (seq xs))))
+      ())
+    coll))
 
 (defn partition
   "Returns a lazy sequence of lists of n items each, at offsets step

Clojure/Clojure.Tests/clojure/test_clojure/sequences.clj

@@ -413,6 +413,49 @@
     (next (to-array [(into-array []) nil])) '(nil)
     (next (to-array [(into-array []) 2 nil])) '(2 nil) ))
 
+(deftest test-nthnext+rest-on-0
+  (are [coll]
+       (and (= (seq coll) (nthnext coll 0))
+            (= coll       (nthrest coll 0)))
+    nil
+    ""
+    ()
+    '(0)
+    []
+    [0]
+    #{}
+    {}
+    {:a 1}
+    (range 5)))
+
+(deftest test-nthnext+rest-on-pos
+  (are [coll n nthnext-expected nthrest-expected]
+       (and (= nthnext-expected (nthnext coll n))
+            (= nthrest-expected (nthrest coll n)))
+
+    ;coll  n  nthnext  nthrest
+    nil    1  nil      ()
+    "abc"  1  '(\b \c) '(\b \c)
+    "abc"  3  nil      ()
+    "abc"  4  nil      ()
+    ()     1  nil      ()
+    '(1)   1  nil      ()
+    '(1)   2  nil      ()
+    '(())  1  nil      ()
+    #{}    1  nil      ()
+    {:a 1} 1  nil      ()
+    []     1  nil      ()
+    [0]    1  nil      ()
+    [0]    2  nil      ()
+    [[] 2 nil] 1 '(2 nil) '(2 nil)
+    [[] 2 nil] 2 '(nil) '(nil)
+    [[] 2 nil] 3 nil ()
+    (sorted-set 1 2 3)     2 '(3)      '(3)
+    (sorted-map :a 1 :b 2) 1 '([:b 2]) '([:b 2])
+    (into-array [])        1 nil       ()
+    (into-array [1])       1 nil       ()
+    (range 5)              3 '(3 4)    '(3 4)
+    (range 5)              5 nil       ()))
 
 (deftest test-last
   (are [x y] (= x y)