LGTM, if you're dead certain this is how it behaves in JSC :-)

On Wed, Apr 15, 2009 at 2:17 PM,  <[email protected]> wrote:
> Reviewers: Kasper Lund,
>
> Description:
> Add mjsunit test for the overriding of read-only properties.
>
> For compatibility, our behavior here does not match the spec.  Added a
> comment to that effect in the test.
>
> Please review this at http://codereview.chromium.org/67164
>
> SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/
>
> Affected files:
>  A     test/mjsunit/override-read-only-property.js
>
>
> Index: test/mjsunit/override-read-only-property.js
> ===================================================================
> --- test/mjsunit/override-read-only-property.js (revision 0)
> +++ test/mjsunit/override-read-only-property.js (revision 0)
> @@ -0,0 +1,64 @@
> +// Copyright 2009 the V8 project authors. All rights reserved.
> +// Redistribution and use in source and binary forms, with or without
> +// modification, are permitted provided that the following conditions are
> +// met:
> +//
> +//     * Redistributions of source code must retain the above copyright
> +//       notice, this list of conditions and the following disclaimer.
> +//     * Redistributions in binary form must reproduce the above
> +//       copyright notice, this list of conditions and the following
> +//       disclaimer in the documentation and/or other materials provided
> +//       with the distribution.
> +//     * Neither the name of Google Inc. nor the names of its
> +//       contributors may be used to endorse or promote products derived
> +//       from this software without specific prior written permission.
> +//
> +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
> +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
> +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
> +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
> +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> +
> +// According to ECMA-262, sections 8.6.2.2 and 8.6.2.3 you're not
> +// allowed to override read-only properties, not even if the read-only
> +// property is in the prototype chain.
> +//
> +// However, for compatibility with WebKit/JSC, we allow the overriding
> +// of read-only properties in prototype chains.
> +
> +function F() {};
> +F.prototype = Number;
> +
> +var original_number_max = Number.MAX_VALUE;
> +
> +// Assignment to a property which does not exist on the object itself,
> +// but is read-only in a prototype takes effect.
> +var f = new F();
> +assertEquals(original_number_max, f.MAX_VALUE);
> +f.MAX_VALUE = 42;
> +assertEquals(42, f.MAX_VALUE);
> +
> +// Assignment to a property which does not exist on the object itself,
> +// but is read-only in a prototype takes effect.
> +f = new F();
> +with (f) {
> +  MAX_VALUE = 42;
> +}
> +assertEquals(42, f.MAX_VALUE);
> +
> +// Assignment to read-only property on the object itself is ignored.
> +Number.MAX_VALUE = 42;
> +assertEquals(original_number_max, Number.MAX_VALUE);
> +
> +// G should be read-only on the global object and the assignment is
> +// ignored.
> +(function G() {
> +  eval("G = 42;");
> +  assertTrue(typeof G === 'function');
> +})();
>
>
>

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