Minimal failing case for core.cljs

README

This Gist shows a potential bug in nashorn 1.8.0_40/1.8.0_45. It works properly in Java 9. It was logged with Review ID: JI-9020683.

After compiling a reduced version of core.cljs (the ClojureScript language) and a minimal test, 
V8 and Spidermonkey print 1 and 10 when the compiled script runs. Nashorn prints 1 and then throws 
the custom exception "Error: No protocol method IDeref defined for type :[object Object]"

The file compiled.js is a distilled version of the real compiled file that has the minimum code to 
fail. Any of the lines marked with // X solve the problem when deleted for 1.8.0_40. Deleting the
commented function solves the problem both for 1.8.0_40 and 1.8.0_45. Said function is not referenced
in the code at all.

compiled.js

namespace = {};

namespace.deref = function(o) {
    if (o.internal_deref != undefined) {
        return o.internal_deref(o);
    } else {
        throw Error(["No protocol method IDeref defined for type :", o].join(""));
    }
};

namespace.Volatile = function(state) {
  this.state = state;
  this.internal_symbol1 = 32768;  // X
  this.internal_symbol2 = 0;      // X
};
namespace.Volatile.prototype.vreset  = function(_, new_state) {
  var self__ = this;
  return self__.state = new_state;
}; // this function is never called, yet deleting results in correct behavior

namespace.Volatile.prototype.internal_deref = function(_) {
  var self__ = this;
  return self__.state;
};
print(function() {
  var v = new namespace.Volatile(1);
  return namespace.deref.call(null, v);
}());

namespace.MyCustomAtom = function(state) {
  this.state = state;
  this.internal_symbol1 = 32768;  // X
  this.internal_symbol2 = 0;      // X
};
namespace.MyCustomAtom.prototype.internal_deref = function(_) {
  var self__ = this;
  return self__.state;
};
print(function() {
  var customAtom = new namespace.MyCustomAtom(10);
  return namespace.deref.call(null, customAtom);
}());

core.cljs

(ns cljs.core)

(defn missing-protocol [proto obj]
  (js/Error.
    (.join (array "No protocol method " proto
             " defined for type :" obj) "")))

(defprotocol IDeref
  (-deref [o]))

(defprotocol IVolatile
  (-vreset! [o new-value]))

(deftype Volatile [^:mutable state]
  IVolatile                    ;; If I Volatile is removed, then it works
  (-vreset! [_ new-state]
    (set! state new-state))

  IDeref
  (-deref [_] state))

core_test.cljs

(ns cljs.core-test)

(js/print (let [v (Volatile. 1)] 
            (-deref v)))

(deftype MyCustomAtom [state]
  IDeref
  (-deref [_] state))

(js/print (let [a0 (MyCustomAtom. 10)]
            (-deref a0)))