CLJS-2956: Stack overflow when specing core =

Author: mfikes

src/main/cljs/cljs/spec/test/alpha.cljc

@@ -46,7 +46,11 @@ returns the set of all symbols naming vars in those nses."
 (defmacro with-instrument-disabled
   "Disables instrument's checking of calls, within a scope."
   [& body]
-  `(let [orig# @#'*instrument-enabled*]
+  ;; Note: In order to read the value of this private var, we employ interop
+  ;; rather than derefing a var special. This eases specing core functions
+  ;; (and infinite recursion) by avoiding code generated by the var special,
+  ;; and also produces more compact / efficient code.
+  `(let [orig# (.-*instrument-enabled* js/cljs.spec.test.alpha)]
      (set! *instrument-enabled* nil)
      (try
        ~@body

src/test/cljs/cljs/spec/test_test.cljs

@@ -111,6 +111,14 @@
                      (fn-2953 "abc"))))
   (is @#'stest/*instrument-enabled*))
 
+(s/fdef cljs.core/= :args (s/+ any?))
+
+(deftest test-cljs-2956
+  (stest/instrument 'cljs.core/=)
+  (is (true? (= 1)))
+  (is (thrown? js/Error (=)))
+  (stest/unstrument 'cljs.core/=))
+
 (defn fn-2975 [x])
 
 (deftest test-2975