CLJS-2847: s/coll-of and s/every gen is very slow if :kind specified without :into

Author: mfikes

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

@@ -825,17 +825,19 @@
     (with-gen* [_ gfn] (merge-spec-impl forms preds gfn))
     (describe* [_] `(merge ~@forms))))
 
+(def ^:private empty-coll {`vector? [], `set? #{}, `list? (), `map? {}})
+
 (defn ^:skip-wiki every-impl
   "Do not call this directly, use 'every', 'every-kv', 'coll-of' or 'map-of'"
   ([form pred opts] (every-impl form pred opts nil))
-  ([form pred {gen-into :into
+  ([form pred {conform-into :into
                describe-form ::describe
                :keys [kind ::kind-form count max-count min-count distinct gen-max ::kfn ::cpred
                       conform-keys ::conform-all]
                :or {gen-max 20}
                :as opts}
     gfn]
-   (let [conform-into gen-into
+   (let [gen-into (if conform-into (empty conform-into) (get empty-coll kind-form))
          spec (delay (specize pred))
          check? #(valid? @spec %)
          kfn (c/or kfn (fn [i v] i))
@@ -926,7 +928,7 @@
            (let [pgen (gensub pred overrides path rmap form)]
              (gen/bind
                (cond
-                 gen-into (gen/return (empty gen-into))
+                 gen-into (gen/return gen-into)
                  kind (gen/fmap #(if (empty? %) % (empty %))
                         (gensub kind overrides path rmap form))
                  :else (gen/return []))