repl: fix auto-complete crash in REPL mode when set env NODE_MODULE_CONTEXTS

[abbshr]

see commit

[yorkie]

The error you got before Cannot convert undefined or null to object can not be fixed by your commit. That's actually you pass a null or undefined value to obj.

To reproduce your bug in source, just call Object.prototype.hasOwnProperty.call(null, {}), but perhaps you may describe how iojs crashed in repl mode 👍

[bnoordhuis]

@abbshr Can you add a regression test? It's not clear to me what this fixes.

[yorkie]

@bnoordhuis i guess there are some infos at https://github.com/abbshr/io.js/commit/9382e0985860bb6bf2e2e8336d5a34d52aa4fff7

[bnoordhuis]

Sorry, those were unrelated statements. :-)

1. I'd like to see a regression test get added to e.g. test/parallel/test-repl.js.

2. I'd like to understand why changing a function to a function variable fixes a TypeError.

[bnoordhuis]

Okay, I think I get it now. With NODE_MODULE_CONTEXTS=1, the hasOwnProperty method from the sandbox object ends up on the global object. The proper fix is this:

diff --git a/lib/module.js b/lib/module.js
index 0d9f093..299c1c1 100644
--- a/lib/module.js
+++ b/lib/module.js
@@ -395,7 +395,7 @@ Module.prototype._compile = function(content, filename) {
     if (self.id !== '.') {
       debug('load submodule');
       // not root module
-      var sandbox = {};
+      var sandbox = Object.create(null);
       for (var k in global) {
         sandbox[k] = global[k];
       }

But the fact that this has been broken since forever is perhaps a strong hint that no one uses NODE_MODULE_CONTEXTS and it should just be removed.

[cjihrig]

@bnoordhuis Does #1162 completely supersede this?

[bnoordhuis]

@cjihrig Yes. There's nothing left to fix after #1162 lands. :-)

[cjihrig]

OK, just double checking. I'm going to close this in favor of #1162. Please reopen if you deem it necessary.