CLJS-3158: Improperly widened cross-param loop/recur inference

Author: mfikes

src/main/clojure/cljs/analyzer.cljc

@@ -2404,7 +2404,11 @@
     (reset! (:flag frame) true)
     (swap! (:tags frame) (fn [tags]
                            (mapv (fn [tag expr]
-                                   (add-types tag (:tag expr)))
+                                   ;; Widen by adding the type of the recur expression, except when recurring with a
+                                   ;; loop local: Since its final widened type is unknown, conservatively assume 'any.
+                                   (if (= :loop (:local expr))
+                                     'any
+                                     (add-types tag (:tag expr))))
                              tags exprs)))
     (assoc {:env env :op :recur :form form}
       :frame frame

src/test/clojure/cljs/analyzer_tests.clj

@@ -2101,3 +2101,12 @@
            (env/with-compiler-env test-cenv
              (:tag (ana/analyze test-env '(let [x ^any []] (if (implements? ICounted x) x nil))))))
         '#{cljs.core/ICounted clj-nil})))
+
+(deftest test-cljs-3158
+  (is (= (ana/no-warn
+           (env/with-compiler-env test-cenv
+             (:tag (analyze test-env '(loop [a "x" b "y"]
+                                        (if (= a 1)
+                                          a
+                                          (recur b 1)))))))
+        'any)))