795903 - getOwnPropertyDescriptor trap can't report a configurable property as non-configurable

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[David Bruant]

This is a spec issue recently found, so Firefox doesn't comply. Test case: 

    var target = {};
    Object.defineProperty(target, 'x', {value:1,configurable:true});
    var proxy = Proxy(target, {
      getOwnPropertyDescriptor: function(target, name) {
        return { value: 2, configurable: false };
      }
    });
    Object.getOwnPropertyDescriptor(proxy, 'x') 


Actual result:
Doesn't throw an error and returns the incompatible property descriptor

Expected result:
throw TypeError

Comment 1

[Nikhil Marathe [:nsm] (No longer reading bugmail, please needinfo?)]

Attachment: Update GetOwnProperty and DefineProperty Traps according to spec changes

Revision 1348497118 of http://wiki.ecmascript.org/doku.php?id=harmony:proxies_spec
changes the algorithm to report error on not just a non-existent property being reported as non-configurable, but also checks that if the property exists and is configurable, the handler doesn't report it as non-configurable

Comment 2

[Florent Fayolle]

Can anyone fix this?
This can drive you insane when you don't know it!

Comment 3

[Nikhil Marathe [:nsm] (No longer reading bugmail, please needinfo?)]

Comment on attachment 668698 [details] [diff] [review]
Update GetOwnProperty and DefineProperty Traps according to spec changes

Really old patch, up for grabs if someone is willing to update.

Comment 4

[Tom S. (please needinfo tschuster)]

This was probably fixed in bug 806299