454969 - destructuring for-in loop fails in top-level scope

Status: RESOLVED FIXED

(Rhino Graveyard :: Core, defect)

Description

[Hannes Wallnoefer]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; de; rv:1.9.0.1) Gecko/2008072820 Firefox/3.0.1
Build Identifier: 

Doing a for-in loop with a destructuring key-value assignment on a top-level scope currently throws a NullPointerException.

Reproducible: Always

Steps to Reproduce:
Run the following in the Rhino shell:

for (var [i, j] in this) print(i, j);
Actual Results:  
Exception in thread "main" java.lang.NullPointerException
	at org.mozilla.javascript.ScriptableObject.getTopLevelScope(ScriptableObject.java:1514)
	at org.mozilla.javascript.ScriptRuntime.setObjectProtoAndParent(ScriptRuntime.java:3291)
	at org.mozilla.javascript.Context.newArray(Context.java:1439)
	at org.mozilla.javascript.ScriptRuntime.enumId(ScriptRuntime.java:2023)
	at org.mozilla.javascript.Interpreter.interpretLoop(Interpreter.java:3581)
	at org.mozilla.javascript.Interpreter.interpret(Interpreter.java:2484)
	at org.mozilla.javascript.InterpretedFunction.call(InterpretedFunction.java:162)
	at org.mozilla.javascript.ContextFactory.doTopCall(ContextFactory.java:401)
	at org.mozilla.javascript.ScriptRuntime.doTopCall(ScriptRuntime.java:3003)
	at org.mozilla.javascript.InterpretedFunction.exec(InterpretedFunction.java:173)
	at org.mozilla.javascript.tools.shell.Main.evaluateScript(Main.java:526)
	at org.mozilla.javascript.tools.shell.Main.processSource(Main.java:386)
	at org.mozilla.javascript.tools.shell.Main.processFiles(Main.java:179)
	at org.mozilla.javascript.tools.shell.Main$IProxy.run(Main.java:100)
	at org.mozilla.javascript.Context.call(Context.java:499)
	at org.mozilla.javascript.ContextFactory.call(ContextFactory.java:511)
	at org.mozilla.javascript.tools.shell.Main.exec(Main.java:162)
	at org.mozilla.javascript.tools.shell.Main.main(Main.java:140)

Comment 1

[Hannes Wallnoefer]

Attachment: Fix: don't pass parent scope to cx.newArray()

The problem is that ScriptRuntime passes the parent scope of the current object to Context.newArray(), which is null for the top level scope.

Comment 2

[Hannes Wallnoefer]

Committed patch to CVS HEAD:

Checking in src/org/mozilla/javascript/ScriptRuntime.java;
/cvsroot/mozilla/js/rhino/src/org/mozilla/javascript/ScriptRuntime.java,v  <--  ScriptRuntime.java
new revision: 1.306; previous revision: 1.305
done

Comment 3

[Norris Boyd]

I copied this fix to the 1.7R2 branch.