CLJS-1539: Parallel compilation fails on circular dependencies

cljs.js-deps/dependency-order-visit now checks for circular dependencies as well

Author: dnolen

src/main/clojure/cljs/analyzer.cljc

@@ -1653,7 +1653,8 @@
    (let [compiler @env/*compiler*]
      (binding [*cljs-dep-set* (vary-meta (conj *cljs-dep-set* lib) update-in [:dep-path] conj lib)]
        (assert (every? #(not (contains? *cljs-dep-set* %)) deps)
-         (str "Circular dependency detected " (-> *cljs-dep-set* meta :dep-path)))
+         (str "Circular dependency detected, "
+           (apply str (interpose " -> " (conj (-> *cljs-dep-set* meta :dep-path) lib)))))
        (doseq [dep deps]
          (when-not (or (not-empty (get-in compiler [::namespaces dep :defs]))
                        (contains? (:js-dependency-index compiler) (name dep))

src/main/clojure/cljs/js_deps.cljc

@@ -142,14 +142,19 @@ case."
     {} deps))
 
 (defn dependency-order-visit
-  [state ns-name]
-  (let [file (get state ns-name)]
-    (if (or (:visited file) (nil? file))
-      state
-      (let [state (assoc-in state [ns-name :visited] true)
-            deps (:requires file)
-            state (reduce dependency-order-visit state deps)]
-        (assoc state :order (conj (:order state) file))))))
+  ([state ns-name]
+    (dependency-order-visit state ns-name []))
+  ([state ns-name seen]
+   (assert (not (some #{ns-name} seen))
+     (str "Circular dependency detected, "
+       (apply str (interpose " -> " (conj seen ns-name)))))
+   (let [file (get state ns-name)]
+     (if (or (:visited file) (nil? file))
+       state
+       (let [state (assoc-in state [ns-name :visited] true)
+             deps  (:requires file)
+             state (reduce #(dependency-order-visit %1 %2 (conj seen ns-name)) state deps)]
+         (assoc state :order (conj (:order state) file)))))))
 
 (defn- pack-string [s]
   (if (string? s)
@@ -167,8 +172,8 @@ case."
   [coll]
   (let [state (build-index (map pack-string coll))]
     (map unpack-string
-         (distinct
-          (:order (reduce dependency-order-visit (assoc state :order []) (keys state)))))))
+      (distinct
+        (:order (reduce dependency-order-visit (assoc state :order []) (keys state)))))))
 
 
 ;; Dependencies

src/test/cljs/circular_deps/a.cljs renamed to src/test/cljs_build/circular_deps/a.cljs

@@ -150,7 +150,7 @@
   (let [out-file (io/file "out/main.js")]
     (.delete out-file)
     (try
-      (build (inputs "src/test/cljs")
+      (build (inputs "src/test/cljs_build")
         {:main 'circular-deps.a
          :optimizations :none
          :verbose true