CLJS-2267: Allow ^:const inlined vars to affect if emission

Author: mfikes

src/main/clojure/cljs/compiler.cljc

@@ -447,15 +447,19 @@
   (when-not (= :statement (:context env))
     (emit-wrap env (emit-constant form))))
 
-(defn truthy-constant? [{:keys [op form]}]
-  (and (= op :constant)
-       form
-       (not (or (and (string? form) (= form ""))
-                (and (number? form) (zero? form))))))
-
-(defn falsey-constant? [{:keys [op form]}]
-  (and (= op :constant)
-       (or (false? form) (nil? form))))
+(defn truthy-constant? [{:keys [op form const-expr]}]
+  (or (and (= op :constant)
+           form
+           (not (or (and (string? form) (= form ""))
+                    (and (number? form) (zero? form)))))
+      (and (some? const-expr)
+           (truthy-constant? const-expr))))
+
+(defn falsey-constant? [{:keys [op form const-expr]}]
+  (or (and (= op :constant)
+           (or (false? form) (nil? form)))
+      (and (some? const-expr)
+           (falsey-constant? const-expr))))
 
 (defn safe-test? [env e]
   (let [tag (ana/infer-tag env e)]

src/test/cljs/cljs/core_test.cljs

@@ -1411,6 +1411,23 @@
       (is (= "#js {:foo/bar 33}" (pr-str (doto (js-obj) (gobject/set "foo/bar" 33)))))
       (is (= "#js {:foo/bar #:var{:quux 66}}" (pr-str (doto (js-obj) (gobject/set "foo/bar" {:var/quux 66}))))))))
 
+(def ^:const true-2267 true)
+(def ^:const false-2267 false)
+(def ^:const nil-2267 nil)
+(def ^:const empty-string-2267 "")
+(def ^:const non-empty-string-2267 "x")
+(def ^:const zero-2267 0)
+(def ^:const non-zero-2267 1)
+
+(deftest test-cljs-2267
+  (is (= :then (if true-2267 :then :else)))
+  (is (= :else (if false-2267 :then :else)))
+  (is (= :else (if nil-2267 :then :else)))
+  (is (= :then (if empty-string-2267 :then :else)))
+  (is (= :then (if non-empty-string-2267 :then :else)))
+  (is (= :then (if zero-2267 :then :else)))
+  (is (= :then (if non-zero-2267 :then :else))))
+
 (comment
   ;; ObjMap
   ;; (let [ks (map (partial str "foo") (range 500))