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Normative: move __proto__ out of annex b
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@devsnek
devsnek committed Sep 24, 2020
1 parent e4679d4 commit c27a2e0
Showing 1 changed file with 122 additions and 139 deletions.
261 changes: 122 additions & 139 deletions spec.html
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Expand Up @@ -57,6 +57,17 @@
emu-table td {
background: #fff;
}
[normative-optional] {
border-left: 5px solid #ff6600;
padding: .5em;
display: block;
background: #ffeedd;
}
[normative-optional]:before {
display: block;
color: #884400;
content: "NORMATIVE OPTIONAL";
}
</style>
</head>
<body>
Expand Down Expand Up @@ -12587,7 +12598,7 @@ <h2>Syntax</h2>
<p>In certain contexts, |ObjectLiteral| is used as a cover grammar for a more restricted secondary grammar. The |CoverInitializedName| production is necessary to fully cover these secondary grammars. However, use of this production results in an early Syntax Error in normal contexts where an actual |ObjectLiteral| is expected.</p>
</emu-note>

<emu-clause id="sec-object-initializer-static-semantics-early-errors">
<emu-clause id="sec-object-initializer-static-semantics-early-errors" oldids="sec-__proto__-property-names-in-object-initializers">
<h1>Static Semantics: Early Errors</h1>
<emu-grammar>PropertyDefinition : MethodDefinition</emu-grammar>
<ul>
Expand All @@ -12605,6 +12616,19 @@ <h1>Static Semantics: Early Errors</h1>
<emu-note>
<p>This production exists so that |ObjectLiteral| can serve as a cover grammar for |ObjectAssignmentPattern|. It cannot occur in an actual object initializer.</p>
</emu-note>
<emu-grammar>
ObjectLiteral : `{` PropertyDefinitionList `}`

ObjectLiteral : `{` PropertyDefinitionList `,` `}`
</emu-grammar>
<ul>
<li>
It is a Syntax Error if PropertyNameList of |PropertyDefinitionList| contains any duplicate entries for *"__proto__"* and at least two of those entries were obtained from productions of the form <emu-grammar>PropertyDefinition : PropertyName `:` AssignmentExpression</emu-grammar>.
</li>
</ul>
<emu-note>
<p>The List returned by PropertyNameList does not include string literal property names defined as using a |ComputedPropertyName|.</p>
</emu-note>
</emu-clause>

<emu-clause id="sec-object-initializer-static-semantics-computedpropertycontains">
Expand Down Expand Up @@ -12767,18 +12791,25 @@ <h1>Runtime Semantics: PropertyDefinitionEvaluation</h1>
<emu-alg>
1. Let _propKey_ be the result of evaluating |PropertyName|.
1. ReturnIfAbrupt(_propKey_).
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true*, then
1. If this |PropertyDefinition| is contained within a |Script| that is being evaluated for JSON.parse (see step <emu-xref href="#step-json-parse-parse"></emu-xref> of JSON.parse), then
1. Let _isProtoSetter_ be *false*.
1. Else, If _propKey_ is the String value *"__proto__"* and if IsComputedPropertyKey(|PropertyName|) is *false*,
1. Let _isProtoSetter_ be *true*.
1. Else,
1. Let _isProtoSetter_ be *false*.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and _isProtoSetter_ is *false*, then
1. Let _propValue_ be NamedEvaluation of |AssignmentExpression| with argument _propKey_.
1. Else,
1. Let _exprValueRef_ be the result of evaluating |AssignmentExpression|.
1. Let _propValue_ be ? GetValue(_exprValueRef_).
1. If _isProtoSetter_ is *true*, then
1. If Type(_propValue_) is either Object or Null, then
1. Return ! _object_.[[SetPrototypeOf]](_propValue_).
1. Return NormalCompletion(~empty~).
1. Assert: _enumerable_ is *true*.
1. Assert: _object_ is an ordinary, extensible object with no non-configurable properties.
1. Return ! CreateDataPropertyOrThrow(_object_, _propKey_, _propValue_).
</emu-alg>
<emu-note>
<p>An alternative semantics for this production is given in <emu-xref href="#sec-__proto__-property-names-in-object-initializers"></emu-xref>.</p>
</emu-note>
</emu-clause>
</emu-clause>

Expand Down Expand Up @@ -26038,6 +26069,91 @@ <h1>Object.prototype.valueOf ( )</h1>
1. Return ? ToObject(*this* value).
</emu-alg>
</emu-clause>

<emu-clause id="sec-object.prototype.__proto__" legacy normative-optional>
<h1>Object.prototype.__proto__</h1>
<p>`Object.prototype.__proto__` is an accessor property with attributes { [[Enumerable]]: *false*, [[Configurable]]: *true* }. The [[Get]] and [[Set]] attributes are defined as follows:</p>

<emu-clause id="sec-get-object.prototype.__proto__">
<h1>get Object.prototype.__proto__</h1>
<p>The value of the [[Get]] attribute is a built-in function that requires no arguments. It performs the following steps when called:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Return ? _O_.[[GetPrototypeOf]]().
</emu-alg>
</emu-clause>

<emu-clause id="sec-set-object.prototype.__proto__">
<h1>set Object.prototype.__proto__</h1>
<p>The value of the [[Set]] attribute is a built-in function that takes an argument _proto_. It performs the following steps when called:</p>
<emu-alg>
1. Let _O_ be ? RequireObjectCoercible(*this* value).
1. If Type(_proto_) is neither Object nor Null, return *undefined*.
1. If Type(_O_) is not Object, return *undefined*.
1. Let _status_ be ? _O_.[[SetPrototypeOf]](_proto_).
1. If _status_ is *false*, throw a *TypeError* exception.
1. Return *undefined*.
</emu-alg>
</emu-clause>
</emu-clause>

<emu-clause id="sec-object.prototype.__defineGetter__" legacy normative-optional>
<h1>Object.prototype.__defineGetter__ ( _P_, _getter_ )</h1>
<p>When the `__defineGetter__` method is called with arguments _P_ and _getter_, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. If IsCallable(_getter_) is *false*, throw a *TypeError* exception.
1. Let _desc_ be PropertyDescriptor { [[Get]]: _getter_, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
1. Let _key_ be ? ToPropertyKey(_P_).
1. Perform ? DefinePropertyOrThrow(_O_, _key_, _desc_).
1. Return *undefined*.
</emu-alg>
</emu-clause>

<emu-clause id="sec-object.prototype.__defineSetter__" legacy normative-optional>
<h1>Object.prototype.__defineSetter__ ( _P_, _setter_ )</h1>
<p>When the `__defineSetter__` method is called with arguments _P_ and _setter_, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. If IsCallable(_setter_) is *false*, throw a *TypeError* exception.
1. Let _desc_ be PropertyDescriptor { [[Set]]: _setter_, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
1. Let _key_ be ? ToPropertyKey(_P_).
1. Perform ? DefinePropertyOrThrow(_O_, _key_, _desc_).
1. Return *undefined*.
</emu-alg>
</emu-clause>

<emu-clause id="sec-object.prototype.__lookupGetter__" legacy normative-optional>
<h1>Object.prototype.__lookupGetter__ ( _P_ )</h1>
<p>When the `__lookupGetter__` method is called with argument _P_, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Let _key_ be ? ToPropertyKey(_P_).
1. Repeat,
1. Let _desc_ be ? _O_.[[GetOwnProperty]](_key_).
1. If _desc_ is not *undefined*, then
1. If IsAccessorDescriptor(_desc_) is *true*, return _desc_.[[Get]].
1. Return *undefined*.
1. Set _O_ to ? _O_.[[GetPrototypeOf]]().
1. If _O_ is *null*, return *undefined*.
</emu-alg>
</emu-clause>

<emu-clause id="sec-object.prototype.__lookupSetter__" legacy normative-optional>
<h1>Object.prototype.__lookupSetter__ ( _P_ )</h1>
<p>When the `__lookupSetter__` method is called with argument _P_, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Let _key_ be ? ToPropertyKey(_P_).
1. Repeat,
1. Let _desc_ be ? _O_.[[GetOwnProperty]](_key_).
1. If _desc_ is not *undefined*, then
1. If IsAccessorDescriptor(_desc_) is *true*, return _desc_.[[Set]].
1. Return *undefined*.
1. Set _O_ to ? _O_.[[GetPrototypeOf]]().
1. If _O_ is *null*, return *undefined*.
</emu-alg>
</emu-clause>
</emu-clause>

<emu-clause id="sec-properties-of-object-instances">
Expand Down Expand Up @@ -37603,7 +37719,7 @@ <h1>JSON.parse ( _text_ [ , _reviver_ ] )</h1>
1. Let _jsonString_ be ? ToString(_text_).
1. [id="step-json-parse-validate"] Parse ! StringToCodePoints(_jsonString_) as a JSON text as specified in ECMA-404. Throw a *SyntaxError* exception if it is not a valid JSON text as defined in that specification.
1. Let _scriptString_ be the string-concatenation of *"("*, _jsonString_, and *");"*.
1. [id="step-json-parse-parse"] Let _completion_ be the result of parsing and evaluating ! StringToCodePoints(_scriptString_) as if it was the source text of an ECMAScript |Script|. The extended PropertyDefinitionEvaluation semantics defined in <emu-xref href="#sec-__proto__-property-names-in-object-initializers"></emu-xref> must not be used during the evaluation.
1. [id="step-json-parse-parse"] Let _completion_ be the result of parsing and evaluating ! StringToCodePoints(_scriptString_) as if it was the source text of an ECMAScript |Script|.
1. Let _unfiltered_ be _completion_.[[Value]].
1. [id="step-json-parse-assert-type"] Assert: _unfiltered_ is either a String, Number, Boolean, Null, or an Object that is defined by either an |ArrayLiteral| or an |ObjectLiteral|.
1. If IsCallable(_reviver_) is *true*, then
Expand Down Expand Up @@ -42412,95 +42528,6 @@ <h1>unescape ( _string_ )</h1>
</emu-annex>
</emu-annex>

<emu-annex id="sec-additional-properties-of-the-object.prototype-object">
<h1>Additional Properties of the Object.prototype Object</h1>

<emu-annex id="sec-object.prototype.__proto__">
<h1>Object.prototype.__proto__</h1>
<p>`Object.prototype.__proto__` is an accessor property with attributes { [[Enumerable]]: *false*, [[Configurable]]: *true* }. The [[Get]] and [[Set]] attributes are defined as follows:</p>

<emu-annex id="sec-get-object.prototype.__proto__">
<h1>get Object.prototype.__proto__</h1>
<p>The value of the [[Get]] attribute is a built-in function that requires no arguments. It performs the following steps when called:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Return ? _O_.[[GetPrototypeOf]]().
</emu-alg>
</emu-annex>

<emu-annex id="sec-set-object.prototype.__proto__">
<h1>set Object.prototype.__proto__</h1>
<p>The value of the [[Set]] attribute is a built-in function that takes an argument _proto_. It performs the following steps when called:</p>
<emu-alg>
1. Let _O_ be ? RequireObjectCoercible(*this* value).
1. If Type(_proto_) is neither Object nor Null, return *undefined*.
1. If Type(_O_) is not Object, return *undefined*.
1. Let _status_ be ? _O_.[[SetPrototypeOf]](_proto_).
1. If _status_ is *false*, throw a *TypeError* exception.
1. Return *undefined*.
</emu-alg>
</emu-annex>
</emu-annex>

<emu-annex id="sec-object.prototype.__defineGetter__">
<h1>Object.prototype.__defineGetter__ ( _P_, _getter_ )</h1>
<p>When the `__defineGetter__` method is called with arguments _P_ and _getter_, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. If IsCallable(_getter_) is *false*, throw a *TypeError* exception.
1. Let _desc_ be PropertyDescriptor { [[Get]]: _getter_, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
1. Let _key_ be ? ToPropertyKey(_P_).
1. Perform ? DefinePropertyOrThrow(_O_, _key_, _desc_).
1. Return *undefined*.
</emu-alg>
</emu-annex>

<emu-annex id="sec-object.prototype.__defineSetter__">
<h1>Object.prototype.__defineSetter__ ( _P_, _setter_ )</h1>
<p>When the `__defineSetter__` method is called with arguments _P_ and _setter_, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. If IsCallable(_setter_) is *false*, throw a *TypeError* exception.
1. Let _desc_ be PropertyDescriptor { [[Set]]: _setter_, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
1. Let _key_ be ? ToPropertyKey(_P_).
1. Perform ? DefinePropertyOrThrow(_O_, _key_, _desc_).
1. Return *undefined*.
</emu-alg>
</emu-annex>

<emu-annex id="sec-object.prototype.__lookupGetter__">
<h1>Object.prototype.__lookupGetter__ ( _P_ )</h1>
<p>When the `__lookupGetter__` method is called with argument _P_, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Let _key_ be ? ToPropertyKey(_P_).
1. Repeat,
1. Let _desc_ be ? _O_.[[GetOwnProperty]](_key_).
1. If _desc_ is not *undefined*, then
1. If IsAccessorDescriptor(_desc_) is *true*, return _desc_.[[Get]].
1. Return *undefined*.
1. Set _O_ to ? _O_.[[GetPrototypeOf]]().
1. If _O_ is *null*, return *undefined*.
</emu-alg>
</emu-annex>

<emu-annex id="sec-object.prototype.__lookupSetter__">
<h1>Object.prototype.__lookupSetter__ ( _P_ )</h1>
<p>When the `__lookupSetter__` method is called with argument _P_, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Let _key_ be ? ToPropertyKey(_P_).
1. Repeat,
1. Let _desc_ be ? _O_.[[GetOwnProperty]](_key_).
1. If _desc_ is not *undefined*, then
1. If IsAccessorDescriptor(_desc_) is *true*, return _desc_.[[Set]].
1. Return *undefined*.
1. Set _O_ to ? _O_.[[GetPrototypeOf]]().
1. If _O_ is *null*, return *undefined*.
</emu-alg>
</emu-annex>
</emu-annex>

<emu-annex id="sec-additional-properties-of-the-string.prototype-object">
<h1>Additional Properties of the String.prototype Object</h1>

Expand Down Expand Up @@ -42759,50 +42786,6 @@ <h1>RegExp.prototype.compile ( _pattern_, _flags_ )</h1>
<emu-annex id="sec-other-additional-features">
<h1>Other Additional Features</h1>

<emu-annex id="sec-__proto__-property-names-in-object-initializers">
<h1>__proto__ Property Names in Object Initializers</h1>
<p>The following Early Error rule is added to those in <emu-xref href="#sec-object-initializer-static-semantics-early-errors"></emu-xref>. When |ObjectLiteral| appears in a context where |ObjectAssignmentPattern| is required the Early Error rule is <b>not</b> applied. In addition, it is not applied when initially parsing a |CoverParenthesizedExpressionAndArrowParameterList| or a |CoverCallExpressionAndAsyncArrowHead|.</p>
<emu-grammar>
ObjectLiteral : `{` PropertyDefinitionList `}`

ObjectLiteral : `{` PropertyDefinitionList `,` `}`
</emu-grammar>
<ul>
<li>
It is a Syntax Error if PropertyNameList of |PropertyDefinitionList| contains any duplicate entries for *"__proto__"* and at least two of those entries were obtained from productions of the form <emu-grammar>PropertyDefinition : PropertyName `:` AssignmentExpression</emu-grammar>.
</li>
</ul>
<emu-note>
<p>The List returned by PropertyNameList does not include string literal property names defined as using a |ComputedPropertyName|.</p>
</emu-note>
<p>In <emu-xref href="#sec-object-initializer-runtime-semantics-propertydefinitionevaluation"></emu-xref> the PropertyDefinitionEvaluation algorithm for the production
<br>
<emu-grammar>PropertyDefinition : PropertyName `:` AssignmentExpression</emu-grammar>
<br>
is replaced with the following definition:</p>
<emu-grammar>PropertyDefinition : PropertyName `:` AssignmentExpression</emu-grammar>
<emu-alg>
1. Let _propKey_ be the result of evaluating |PropertyName|.
1. ReturnIfAbrupt(_propKey_).
1. If _propKey_ is the String value *"__proto__"* and if IsComputedPropertyKey(|PropertyName|) is *false*, then
1. Let _isProtoSetter_ be *true*.
1. Else,
1. Let _isProtoSetter_ be *false*.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and _isProtoSetter_ is *false*, then
1. Let _propValue_ be NamedEvaluation of |AssignmentExpression| with argument _propKey_.
1. Else,
1. Let _exprValueRef_ be the result of evaluating |AssignmentExpression|.
1. Let _propValue_ be ? GetValue(_exprValueRef_).
1. If _isProtoSetter_ is *true*, then
1. If Type(_propValue_) is either Object or Null, then
1. Return _object_.[[SetPrototypeOf]](_propValue_).
1. Return NormalCompletion(~empty~).
1. Assert: _enumerable_ is *true*.
1. Assert: _object_ is an ordinary, extensible object with no non-configurable properties.
1. Return ! CreateDataPropertyOrThrow(_object_, _propKey_, _propValue_).
</emu-alg>
</emu-annex>

<emu-annex id="sec-labelled-function-declarations">
<h1>Labelled Function Declarations</h1>
<p>Prior to ECMAScript 2015, the specification of |LabelledStatement| did not allow for the association of a statement label with a |FunctionDeclaration|. However, a labelled |FunctionDeclaration| was an allowable extension for non-strict code and most browser-hosted ECMAScript implementations supported that extension. In ECMAScript 2015, the grammar productions for |LabelledStatement| permits use of |FunctionDeclaration| as a |LabelledItem| but <emu-xref href="#sec-labelled-statements-static-semantics-early-errors"></emu-xref> includes an Early Error rule that produces a Syntax Error if that occurs. For web browser compatibility, that rule is modified with the addition of the <ins>highlighted</ins> text:</p>
Expand Down

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