[Webkit-unassigned] [Bug 38970] New: Non-enumerable property fails to shadow inherited enumerable property from for-in

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=38970

           Summary: Non-enumerable property fails to shadow inherited
                    enumerable property from for-in
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Macintosh Intel
               URL: https://mail.mozilla.org/pipermail/es5-discuss/2010-Ma
                    y/003536.html
        OS/Version: Mac OS X 10.5
            Status: UNCONFIRMED
          Severity: Minor
          Priority: P2
         Component: JavaScriptCore
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: erights at gmail.com
                CC: erights at gmail.com


At https://mail.mozilla.org/pipermail/es5-discuss/2010-May/003536.html Allen clarifies that, according to the ES5 spec,

    function showProps(obj) {
      var result = [];
      for (var k in obj) {
        result.push(k, ': ', ''+obj[k], '\n');
      }
      return result.join('');
    }
    var base = {x:8};
    var derived = Object.create(base, {x: {value: 9, enumerable: false}});
    showProps(derived);

Should print the empty string. On WebKit nightly as of this writing, it prints "x: 9". Besides violating the spec, it is also the less useful behavior for the common for-in loop behavior (shown above as "obj[k]") of using the key to index into the object being iterated, in order to get the corresponding value.

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