Replication Steps

1. Download latest ClojureScript JAR

   curl -O -L 'https://github.com/clojure/clojurescript/releases/download/r1.7.170/cljs.jar'
   

2. Build

   java -cp cljs.jar:src clojure.main build.clj
   

3. Observe compiler warnings

   WARNING: Use of undeclared Var type-leak-test-minimal.core/clj-nil at line 34 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/number at line 36 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/string at line 37 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/function at line 41 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/object at line 42 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/clj-nil at line 45 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/number at line 47 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/string at line 48 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/function at line 52 src/type_leak_test_minimal/core.cljs
   WARNING: Use of undeclared Var type-leak-test-minimal.core/object at line 53 src/type_leak_test_minimal/core.cljs
   

4. Observe correct runtime behavior

   open index.html
   # view results in browser JavaScript console