always deep-merge ns-info, then macros can emit ns forms that augments the existing ns

Author: swannodette

src/main/clojure/cljs/analyzer.cljc

@@ -3166,7 +3166,16 @@
              :requires       requires
              :renames        (merge renames core-renames)
              :imports        imports}]
-        (swap! env/*compiler* update-in [::namespaces name] merge ns-info)
+        (swap! env/*compiler* update-in [::namespaces name]
+          (fn [the-ns]
+            ;; just merge - do not replace - then macros can emit
+            ;; modifications to the ns
+            (reduce-kv
+              (fn [the-ns k v]
+                (if (map? v)
+                  (update the-ns k merge v)
+                  (assoc the-ns k v)))
+              the-ns ns-info)))
         (merge {:op      :ns
                 :env     env
                 :form    form

src/test/clojure/cljs/analyzer_tests.clj

@@ -1496,9 +1496,14 @@
 (deftest test-cljs-3276-require-from-macro
   (let [cenv (env/default-compiler-env)]
     (env/with-compiler-env cenv
-      (ana/analyze-form-seq
-       '[(ns test.foo
-           (:require-macros [cljs-3276.macros :refer [macro-that-requires]]))
-         (macro-that-requires)]))
-    (is (= '{cljs-3276.foo cljs-3276.foo} (get-in @cenv [::ana/namespaces 'test.foo :requires])))
-    (is (contains? (get @cenv ::ana/namespaces) 'cljs-3276.foo))))
+      (comp/with-core-cljs {}
+        (fn []
+          (ana/analyze-form-seq
+            '[(ns test.foo
+                (:require [clojure.set :as set])
+                (:require-macros [cljs-3276.macros :refer [macro-that-requires]]))
+              (macro-that-requires)]))))
+    (is (= '{set clojure.set, clojure.set clojure.set, cljs-3276.foo cljs-3276.foo}
+            (get-in @cenv [::ana/namespaces 'test.foo :requires])))
+    (is (contains? (get @cenv ::ana/namespaces) 'cljs-3276.foo))
+    (is (contains? (get @cenv ::ana/namespaces) 'clojure.set))))