423557 - Compiler chokes on keywords as object properties

Status: RESOLVED FIXED

(Rhino Graveyard :: Compiler, defect)

Description

[Mark]

User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.12) Gecko/20080201 Firefox/2.0.0.12
Build Identifier: rhino1_6R7

The following snippets cause compiler errors, all are valid:

var x = {int:5};
var x = {for:5};
var x = {continue:5};
var x = {while:5};
...etc

var x = {'int': 5}; // passes this, but...
alert(x.int);       // fails

Reproducible: Always

Steps to Reproduce:
1.
2.
3.

Comment 1

[Mark]

I know alert isn't valid, I wasn't thinking about it.  Change that to whatever, the "x.int" still breaks.

Comment 2

[Mark]

Okay, looking into this more I found that Rhino follows the ECMAScript Grammar on this while every browser I've tested (FF, Opera, Safari, IE) allows the behavior.  I suppose the question is what Rhino should be following closer  :-)  A simple browser test:

javascript:alert({int:5}.int);



From ECMA-262 E3:

ReservedWord :: See section 7.5.1 
Keyword 
FutureReservedWord 
NullLiteral 
BooleanLiteral 
 
Keyword :: one of See section 7.5.2 
break else new var 
case finally return void 
catch for switch while 
continue function this with 
default if throw 
delete in try 
do instanceof typeof 
 
FutureReservedWord :: one of See section 7.5.3 
abstract enum int short 
boolean export interface static 
byte extends long super 
char final native synchronized 
class float package throws 
const goto private transient 
debugger implements protected volatile 
double import public 

Identifier :: IdentifierName but not ReservedWord

Comment 3

[Steve Yegge]

IE6 permits this:

var foo = {int: 5}

but NOT any of the following:

var foo = {return: 5}
var foo = {for: 5}
var foo = {while: 5}
var foo = {if: 5}

So technically IE is only permitting non-keyword reserved words as identifiers.  (Haven't verified it for all keywords, but that's my hunch.)

Comment 4

[Hannes Wallnoefer]

Attachment: Allow keywords as property identifiers

This patch allows all keywords as property ids if Context.FEATURE_RESERVED_KEYWORD_AS_IDENTIFIER is enabled. In the meantime all major browsers allow this, so it's time to catch up.

Comment 5

[Hannes Wallnoefer]

Committed my patch.

Checking in src/org/mozilla/javascript/Token.java;
/cvsroot/mozilla/js/rhino/src/org/mozilla/javascript/Token.java,v  <--  Token.java
new revision: 1.47; previous revision: 1.46
done
Checking in src/org/mozilla/javascript/Parser.java;
/cvsroot/mozilla/js/rhino/src/org/mozilla/javascript/Parser.java,v  <--  Parser.java
new revision: 1.157; previous revision: 1.156
done
RCS file: /cvsroot/mozilla/js/rhino/testsrc/doctests/423557.doctest,v
done
Checking in testsrc/doctests/423557.doctest;
/cvsroot/mozilla/js/rhino/testsrc/doctests/423557.doctest,v  <--  423557.doctest
initial revision: 1.1
done