CLJS-3473: False positive warning for + with throw expression

Author: borkdude

src/main/clojure/cljs/analyzer.cljc

@@ -1599,6 +1599,20 @@ x                          (not (contains? ret :info)))
                              else-tag #{else-tag})]
               (into then-tag else-tag))))))))
 
+(defn infer-try
+  [env ast]
+  (let [body-tag (infer-tag env (:body ast))
+        catch-tag (infer-tag env (:catch ast))]
+    (cond
+      #?(:clj (= body-tag impl/IGNORE_SYM)
+         :cljs (symbol-identical? body-tag impl/IGNORE_SYM))
+      catch-tag
+      #?(:clj (= catch-tag impl/IGNORE_SYM)
+         :cljs (symbol-identical? catch-tag impl/IGNORE_SYM))
+      body-tag
+      :else
+      (add-types body-tag catch-tag))))
+
 (defn js-var? [ast]
   (= :js-var (:op ast)))
 
@@ -1638,7 +1652,7 @@ x                          (not (contains? ret :info)))
         :throw    impl/IGNORE_SYM
         :let      (infer-tag env (:body ast))
         :loop     (infer-tag env (:body ast))
-        :try      (infer-tag env (:body ast))
+        :try      (infer-try env ast)
         :do       (infer-tag env (:ret ast))
         :fn-method (infer-tag env (:body ast))
         :def      (infer-tag env (:init ast))

src/test/clojure/cljs/analyzer_tests.clj

@@ -1562,6 +1562,17 @@
     (is (= 1 (count @ws)))
     (is (string/starts-with? (first @ws) "Wrong number of args (2) passed to Foo"))))
 
+(deftest test-cljs-3473
+  (let [ws (atom [])]
+    (ana/with-warning-handlers [(collecting-warning-handler ws)]
+      (analyze (ana/empty-env)
+               '(+ 1 2 (try (throw (throw 2)) (catch :default _ 1)))))
+    (is (empty? @ws))
+    (ana/with-warning-handlers [(collecting-warning-handler ws)]
+      (analyze (ana/empty-env)
+               '(+ 1 2 (try (throw (throw 2)) (catch :default _ "1")))))
+    (is (string/starts-with? (first @ws) "cljs.core/+, all arguments must be numbers, got [number string] instead"))))
+
 (deftest test-cljs-3401
   (is (not= (ana/gen-constant-id '_PLUS_)
             (ana/gen-constant-id '+)))