CLJS-2995: Instrumented self-calling multi-arity fn throws maximum call stack exceeded with optimizations advanced

Fixed by calling static arities instead of apply

Author: borkdude

src/main/cljs/cljs/spec/test/alpha.cljc

@@ -288,16 +288,22 @@ spec itself will have an ::s/failure value in ex-data:
                (fn [sym]
                  (do `(check-1 '~sym nil nil ~opts-sym)))))]))))
 
-(defmacro ^:private maybe-setup-static-dispatch [f ret arity]
+(defmacro ^:private maybe-setup-static-dispatch [f ret conform! arity]
   (let [arity-accessor (symbol (str ".-cljs$core$IFn$_invoke$arity$" arity))
         argv (mapv #(symbol (str "arg" %)) (range arity))]
-    `(when (some? (~arity-accessor ~f))
+    `(when-some [ac# (~arity-accessor ~f)]
        (set! (~arity-accessor ~ret)
-         (fn ~argv
-           (apply ~ret ~argv))))))
-
-(defmacro ^:private setup-static-dispatches [f ret max-arity]
+             (fn ~argv
+               (if *instrument-enabled*
+                 (with-instrument-disabled
+                   (~conform! ~argv)
+                   (binding [*instrument-enabled* true]
+                     (ac# ~@argv)))
+                 (ac# ~@argv)))))))
+
+(defmacro ^:private setup-static-dispatches [f ret conform! max-arity]
+  ;; ret is for when we don't have arity info
   `(do
      ~@(mapv (fn [arity]
-               `(maybe-setup-static-dispatch ~f ~ret ~arity))
+               `(maybe-setup-static-dispatch ~f ~ret ~conform! ~arity))
          (range (inc max-arity)))))

src/main/cljs/cljs/spec/test/alpha.cljs

@@ -87,6 +87,7 @@
 (defn- spec-checking-fn
   [v f fn-spec]
   (let [fn-spec (@#'s/maybe-spec fn-spec)
+        args-spec (:args fn-spec)
         conform! (fn [v role spec data args]
                    (let [conformed (s/conform spec data)]
                      (if (= ::s/invalid conformed)
@@ -112,15 +113,18 @@
                           pure-variadic?)
                    (.cljs$core$IFn$_invoke$arity$variadic f)
                    (apply f args)))
-        ret (fn [& args]
-              (if *instrument-enabled*
-                (with-instrument-disabled
-                  (when (:args fn-spec) (conform! v :args (:args fn-spec) args args))
-                  (binding [*instrument-enabled* true]
-                    (apply' f args)))
-                (apply' f args)))]
-    (when-not pure-variadic?
-      (setup-static-dispatches f ret 20)
+        conform!* #(conform! v :args args-spec % %)
+        ret (if args-spec
+              (fn [& args]
+                (if *instrument-enabled*
+                  (with-instrument-disabled
+                    (conform!* args)
+                    (binding [*instrument-enabled* true]
+                      (apply' f args)))
+                  (apply' f args)))
+              f)]
+    (when (and (not pure-variadic?) args-spec)
+      (setup-static-dispatches f ret conform!* 20)
       (when-some [variadic (.-cljs$core$IFn$_invoke$arity$variadic f)]
         (set! (.-cljs$core$IFn$_invoke$arity$variadic ret)
           (fn [& args]

src/test/cljs/cljs/spec/test_test.cljs

@@ -117,3 +117,20 @@
   (testing "instrument and unstrument return empty coll when no fdef exists"
     (is (empty? (stest/instrument `fn-2975)))
     (is (empty? (stest/unstrument `fn-2975)))))
+
+(defn fn-2995
+  ([] (fn-2995 0))
+  ([a] (fn-2995 a 1))
+  ([a b] [a b]))
+
+(s/fdef fn-2995
+  :args (s/cat :a (s/? number?)
+               :b (s/? number?)))
+
+(deftest test-2995
+  (stest/instrument `fn-2995)
+  (testing "instrumented self-calling multi-arity function works"
+    (is (= [0 1] (fn-2995 0 1)))
+    (is (= [0 1] (fn-2995 0)))
+    (is (= [0 1] (fn-2995 0)))
+    (is (thrown? js/Error (fn-2995 "not a number")))))