CLJS-639: warning when records initialized incorrectly

When not a defrecord internal constructor call check the arity of the
instantiation form against the fields - ignoring extmap, meta and
hash. This is done by setting :internal-ctor meta on the record symbol,
otherwise the logic is identical to deftype*. Fix some formatting.

src/clj/cljs/analyzer.clj

@@ -758,9 +758,10 @@
          argexprs (vec (map #(analyze enve %) args))
          known-num-fields (:num-fields (resolve-existing-var env ctor))
          argc (count args)]
-     (when (and known-num-fields (not= known-num-fields argc) (:fn-arity *cljs-warnings*))
+     (when (and (:fn-arity *cljs-warnings*)
+                (not (-> ctor meta :internal-ctor))
+                known-num-fields (not= known-num-fields argc))
        (warning :fn-arity env {:argc argc :ctor ctor}))
-
      {:env env :op :new :form form :ctor ctorexpr :args argexprs
       :children (into [ctorexpr] argexprs)})))
 
@@ -961,7 +962,10 @@
   (let [t (:name (resolve-var (dissoc env :locals) tsym))]
     (swap! env/*compiler* update-in [::namespaces (-> env :ns :name) :defs tsym]
            (fn [m]
-             (let [m (assoc (or m {}) :name t :type true)]
+             (let [m (assoc (or m {})
+                       :name t
+                       :type true
+                       :num-fields (count fields))]
                (merge m
                  {:protocols (-> tsym meta :protocols)}
                  (source-info tsym env)))))

src/clj/cljs/core.clj

@@ -908,18 +908,19 @@
          (~'defrecord* ~tagname ~hinted-fields ~pmasks)
          (extend-type ~tagname ~@(dt->et tagname impls fields true))))))
 
-(defn- build-map-factory
-  [rsym rname fields]
+(defn- build-map-factory [rsym rname fields]
   (let [fn-name (symbol (core/str 'map-> rsym))
-	ms (gensym)
-	ks (map keyword fields)
-	getters (map (fn [k] `(~k ~ms)) ks)]
-    `(defn ~fn-name
-       [~ms]
+        ms (gensym)
+        ks (map keyword fields)
+        getters (map (fn [k] `(~k ~ms)) ks)]
+    `(defn ~fn-name [~ms]
        (new ~rname ~@getters nil (dissoc ~ms ~@ks)))))
 
 (defmacro defrecord [rsym fields & impls]
-  (let [r (:name (cljs.analyzer/resolve-var (dissoc &env :locals) rsym))]
+  (let [rsym (vary-meta rsym assoc :internal-ctor true)
+        r    (vary-meta
+               (:name (cljs.analyzer/resolve-var (dissoc &env :locals) rsym))
+               assoc :internal-ctor true)]
     `(let []
        ~(emit-defrecord &env rsym r fields impls)
        (set! (.-cljs$lang$type ~r) true)