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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Function#arguments and Function#caller break the invariability of nonconfigurable, nonwritable properties"
href="https://bugs.webkit.org/show_bug.cgi?id=158116">158116</a>
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<th>Summary</th>
<td>Function#arguments and Function#caller break the invariability of nonconfigurable, nonwritable properties
</td>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>Product</th>
<td>WebKit
</td>
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<th>Version</th>
<td>WebKit Nightly Build
</td>
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<th>Hardware</th>
<td>Unspecified
</td>
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<th>OS</th>
<td>Unspecified
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>Normal
</td>
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<th>Priority</th>
<td>P2
</td>
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<th>Component</th>
<td>JavaScriptCore
</td>
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
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<th>Reporter</th>
<td>claude.pache@gmail.com
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<p>
<div>
<pre>According to [ES6 6.7.1.3] Invariants of the Essential Internal Methods:
If a property P is described as a data property with Desc.[[Value]] equal to v and Desc.[[Writable]] and Desc.[[Configurable]] are both false, then the SameValue must be returned for the Desc.[[Value]] attribute of the property on all future calls to [[GetOwnProperty]] ( P ).
[ES6 6.7.1.3]: <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-invariants-of-the-essential-internal-methods">http://www.ecma-international.org/ecma-262/6.0/#sec-invariants-of-the-essential-internal-methods</a>
Testcase against `Function#arguments`
```js
function f() { return Object.getOwnPropertyDescriptor(f, 'arguments'); }
Object.getOwnPropertyDescriptor(f, 'arguments');
// value: null, writable: false, configurable: false
f();
// value: Arguments[], writable: false, configurable: false
```
Testcase against `Function#caller`
```js
function g() { return Object.getOwnPropertyDescriptor(g, 'caller'); }
function h() { return g(); }
Object.getOwnPropertyDescriptor(g, 'caller');
// value: null, writable: false, configurable: false
h();
// value: function h(), writable: false, configurable: false
```
Suggested fix: Use getters.
Similar bug: <a class="bz_bug_link
bz_status_NEW "
title="NEW - Nonstandard RegExp own properties do not observe invariability of nonwritable, nonconfigurable property"
href="show_bug.cgi?id=151348">Bug 151348</a></pre>
</div>
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