Bug 153441 – Global lexical declarations should shadow configurable global properties

• Status: RESOLVED
• Resolution: DUPLICATE
• Component: JavaScriptCore

[Elliott Sprehn]

ex.

class Node { }

SyntaxError: Can't create duplicate variable that shadows a global property: 'Node'

but you can write

var Node = class Node { }

this works fine in Chrome and Firefox 45.

[Elliott Sprehn]

This is still broken, I think something is wrong in your lexical scoping.

[Elliott Sprehn]

I just checked today's nightly: r202375 and it still happens.

[Adam Klein]

In general, it seems that JSC refuses to create lexical bindings that shadow configurable properties on the global object, contra the spec (see https://tc39.github.io/ecma262/#sec-hasrestrictedglobalproperty). Here's a DOM-less repro:

>>> let Array = 5
Exception: SyntaxError: Can't create duplicate variable that shadows a global property: 'Array'

or one with a self-created property:

>>> Object.defineProperty(this, 'foo', {value: 5, configurable: true, writable: true})
[object global]
>>> let foo = 10
Exception: SyntaxError: Can't create duplicate variable that shadows a global property: 'Foo'

[Saam Barati]

*** This bug has been marked as a duplicate of bug 148763 ***