CLJS-1600: Destructuring defprotocol fn args causes defrecord impls to silently fail

Author: anmonteiro

src/main/clojure/cljs/core.cljc

@@ -1939,20 +1939,27 @@
                                 (core/str "Invalid protocol, " psym
                                   " defines method " mname " with arity 0"))))))
              expand-sig (core/fn [fname slot sig]
-                          `(~sig
-                             (if (and (not (nil? ~(first sig)))
-                                      (not (nil? (. ~(first sig) ~(symbol (core/str "-" slot)))))) ;; Property access needed here.
-                               (. ~(first sig) ~slot ~@sig)
-                               (let [x# (if (nil? ~(first sig)) nil ~(first sig))
-                                     m# (aget ~(fqn fname) (goog/typeOf x#))]
-                                 (if-not (nil? m#)
-                                   (m# ~@sig)
-                                   (let [m# (aget ~(fqn fname) "_")]
-                                     (if-not (nil? m#)
-                                       (m# ~@sig)
-                                       (throw
-                                         (missing-protocol
-                                           ~(core/str psym "." fname) ~(first sig))))))))))
+                          (core/let [sig (core/if-not (every? core/symbol? sig)
+                                           (mapv (core/fn [arg]
+                                                   (core/cond
+                                                     (core/symbol? arg) arg
+                                                     (core/and (map? arg) (some? (:as arg))) (:as arg)
+                                                     :else (gensym))) sig)
+                                           sig)]
+                            `(~sig
+                              (if (and (not (nil? ~(first sig)))
+                                    (not (nil? (. ~(first sig) ~(symbol (core/str "-" slot)))))) ;; Property access needed here.
+                                (. ~(first sig) ~slot ~@sig)
+                                (let [x# (if (nil? ~(first sig)) nil ~(first sig))
+                                      m# (aget ~(fqn fname) (goog/typeOf x#))]
+                                  (if-not (nil? m#)
+                                    (m# ~@sig)
+                                    (let [m# (aget ~(fqn fname) "_")]
+                                      (if-not (nil? m#)
+                                        (m# ~@sig)
+                                        (throw
+                                          (missing-protocol
+                                            ~(core/str psym "." fname) ~(first sig)))))))))))
              psym (core/-> psym
                     (vary-meta update-in [:jsdoc] conj
                       "@interface")

src/test/cljs/cljs/core_test.cljs

@@ -3262,6 +3262,37 @@
   (is (= (get #js [\h \i] 1.7 :not-found) \i))
   (is (= (get "hi" 1.7 :not-found) \i)))
 
+(defprotocol CLJS-1600-IFoo
+  (foo-fn [_ {:keys [a b] :as x}]))
+
+(defrecord CLJS-1600-Foo []
+  CLJS-1600-IFoo
+  (foo-fn [_ {:keys [a b] :as args}]
+    args))
+
+(deftest test-cljs-1600
+  (let [foo (reify
+              CLJS-1600-IFoo
+              (foo-fn [_ {:keys [a b] :as args}]
+                args))]
+    (is (= (foo-fn (->CLJS-1600-Foo) {:a 1 :b 2})
+           {:a 1 :b 2}))
+    (is (= (foo-fn foo {:a 1 :b 2})
+           {:a 1 :b 2})))
+  ;; test that the destructuring works
+  (let [foo (reify
+              CLJS-1600-IFoo
+              (foo-fn [_ {:keys [a b] :as args}]
+                {:a a :b b}))]
+    (is (= (foo-fn foo {:a 1 :b 2})
+           {:a 1 :b 2})))
+  (let [foo (reify
+              CLJS-1600-IFoo
+              (foo-fn [_ {:keys [a b c] :or {c 3}}]
+                {:c c}))]
+    (is (= (foo-fn foo {:a 1 :b 2})
+           {:c 3}))))
+
 (comment
   ;; ObjMap
   ;; (let [ks (map (partial str "foo") (range 500))