CLJS-1228: cljs.util/topo-sort is polynomial on larger dependency graphs

remove ns-dependencies, remove corresponding build api. remove tests.

simplify cljs.compiler/requires-compilation? now that we know that the
build order is fixed.

src/main/clojure/cljs/analyzer.cljc

@@ -782,31 +782,6 @@
         (when ns
           (get-in namespaces [ns :macros sym]))))))
 
-(defn ns-dependents
-  "Given a namespace as a symbol and a map from namespace symbol to
-   namespace information return the topologically sorted list of all
-   dependent namespaces. The map values of the optional second argument must
-   be maps with a :requires set of symbols, a :requires map of symbol -> alias
-   (analyzer format) or a :requires vector of munged namespace strings
-   (closure format)."
-  ([ns] (ns-dependents ns (get @env/*compiler* ::namespaces)))
-  ([ns ns-map]
-   (letfn [(parent? [parent [child {:keys [requires] :as ns-info}]]
-             (when-not (= parent child)
-               (cond
-                 (or (map? requires)
-                     (set? requires)) (contains? requires parent)
-                 (vector? requires) (some #{(munge (name parent))} requires))))]
-     (topo-sort ns
-       (fn [ns']
-         (set (map first (filter #(parent? ns' %) ns-map))))))))
-
-(comment
-  (ns-dependents 'bar
-    '{bar {:requires #{cljs.core}}
-      foo {:requires #{cljs.core bar}}})
-  )
-
 (declare analyze analyze-symbol analyze-seq)
 
 (def specials '#{if def fn* do let* loop* letfn* throw try recur new set!

src/main/clojure/cljs/build/api.clj

@@ -70,20 +70,6 @@
                          (intersection namespaces-set (-> x :require-macros vals set))))
          (vals (:cljs.analyzer/namespaces @state)))))))
 
-(defn cljs-ns-dependents
-  "Given a namespace symbol return a seq of all dependent
-  namespaces sorted in dependency order. Will include
-  transient dependents."
-  ([ns]
-   (cljs-ns-dependents
-     (if-not (nil? env/*compiler*)
-       env/*compiler*
-       (env/default-compiler-env))
-     ns))
-  ([state ns]
-   (env/with-compiler-env state
-     (ana/ns-dependents ns))))
-
 (defn parse-js-ns
   "Given a Google Closure style JavaScript file or resource return the namespace
   information for the given file. Only returns the value extracted from the

src/main/clojure/cljs/closure.clj

@@ -1769,8 +1769,8 @@
              (assoc :js-dependency-index (deps/js-dependency-index all-opts))
              ;; Save list of sources for cljs.analyzer/locate-src - Juho Teperi
              (assoc :sources (-find-sources source all-opts))))
-         (binding [comp/*dependents* (when-not (false? (:recompile-dependents opts))
-                                       (atom {:recompile #{} :visited #{}}))
+         (binding [comp/*recompiled* (when-not (false? (:recompile-dependents opts))
+                                       (atom #{}))
                    ana/*cljs-static-fns*
                    (or (and (= (:optimizations opts) :advanced)
                             (not (false? (:static-fns opts))))

src/main/clojure/cljs/compiler.cljc

@@ -35,7 +35,7 @@
 
 (def js-reserved ana/js-reserved)
 
-(def ^:dynamic *dependents* nil)
+(def ^:dynamic *recompiled* nil)
 (def ^:dynamic *inputs* nil)
 (def ^:dynamic *source-map-data* nil)
 (def ^:dynamic *lexical-renames* {})
@@ -1268,7 +1268,7 @@
      "Return true if the src file requires compilation."
      ([src dest] (requires-compilation? src dest nil))
      ([^File src ^File dest opts]
-      (let [{:keys [ns]} (ana/parse-ns src)]
+      (let [{:keys [ns requires]} (ana/parse-ns src)]
         (ensure
           (or (not (.exists dest))
               (> (.lastModified src) (.lastModified dest))
@@ -1283,10 +1283,8 @@
                 (if (= (:optimizations opts) :none)
                   (not (.exists (io/file (str (.getPath dest) ".map"))))
                   (not (get-in @env/*compiler* [::compiled-cljs (.getAbsolutePath dest)]))))
-              (let [{:keys [recompile visited]}
-                    (and *dependents* @*dependents*)]
-                (and (contains? recompile ns)
-                     (not (contains? visited ns))))))))))
+              (when-let [recompiled' (and *recompiled* @*recompiled*)]
+                (some requires recompiled'))))))))
 
 #?(:clj
    (defn compile-file
@@ -1331,13 +1329,8 @@
                                (not= :interactive (:mode opts)))
                       (swap! env/*compiler* update-in [::ana/namespaces] dissoc ns))
                     (let [ret (compile-file* src-file dest-file opts)]
-                      (when *dependents*
-                        (swap! *dependents*
-                          (fn [{:keys [recompile visited]}]
-                            {:recompile (into recompile
-                                          (ana/ns-dependents ns
-                                            (merge *inputs* nses)))
-                             :visited (conj visited ns)})))
+                      (when *recompiled*
+                        (swap! *recompiled* conj ns))
                       ret))
                   (do
                     ;; populate compilation environment with analysis information

src/test/clojure/cljs/analyzer_tests.clj

@@ -305,39 +305,6 @@
     (is (= (meta (:name (a/analyze ns-env '(ns ^{:foo bar} weeble {:foo baz}))))
            {:foo 'baz}))))
 
-(def test-deps-env (atom
-                    {:cljs.analyzer/namespaces
-                     {'file-reloading {:requires {'utils 'utils}}
-                      'core           {:requires {'file-reloading 'file-reloading}}
-                      'dev            {:requires {'client 'client
-                                                  'core 'core}}
-                      'client         {:requires {'utils 'utils}}
-                      'utils          {:requires {}}}}))
-
-(deftest test-ns-dependents
-  (binding [env/*compiler* test-deps-env]
-    (is (= (set (a/ns-dependents 'client))
-           #{'dev}))
-    (is (= (set (a/ns-dependents 'core))
-           #{'dev}))
-    (is (= (set (a/ns-dependents 'dev))
-           #{}))
-
-    ;; if 'file-reloading returns 'core
-    (is (= (set (a/ns-dependents 'file-reloading))
-           #{'dev 'core}))
-
-    ;; how can 'utils include 'file-reloading but not 'core
-    ;; FAILS with
-    ;; actual: (not (= #{file-reloading dev client} #{file-reloading dev client core}))
-    (is (= (set (a/ns-dependents 'utils))
-           #{'file-reloading 'dev 'client 'core}))))
-
-(deftest test-ns-dependents-custom-ns-map
-  (let [ns-map '{bar {:requires #{cljs.core}}
-                 foo {:requires #{cljs.core bar}}}]
-    (is (= (set (a/ns-dependents 'bar ns-map)) #{'foo}))))
-
 (deftest test-cljs-1105
   ;; munge turns - into _, must preserve the dash first
   (is (not= (a/gen-constant-id :test-kw)

src/test/clojure/cljs/build_api_tests.clj

@@ -104,19 +104,6 @@
            (:require [graph.foo.core :as foo]
                      [graph.bar.core :as bar]))))))
 
-(deftest test-cljs-ns-dependencies
-  (is (= (env/with-compiler-env test-cenv
-           (cljs-ns-dependents 'clojure.string))
-        '(cljs.user)))
-  (is (= (env/with-compiler-env test-cenv
-           (cljs-ns-dependents 'foo.core))
-        '(bar.core baz.core)))
-  (is (= (env/with-compiler-env test-cenv
-           (cljs-ns-dependents 'graph.foo.core))
-        '(graph.bar.core graph.baz.core)))
-  (is (= (cljs-ns-dependents test-cenv 'graph.foo.core)
-        '(graph.bar.core graph.baz.core))))
-
 (deftest cljs-1469
   (let [srcs "samples/hello/src"
         [common-tmp app-tmp] (mapv #(File/createTempFile  % ".js")