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Normative: Allow [[ReferencedName]] in Reference Records to be a not-yet-resolved property key #3307

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May 30, 2024
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Normative: Allow [[ReferencedName]] in Reference Records to be a not-yet-resolved property key #3307

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40 changes: 26 additions & 14 deletions spec.html
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Original file line number Diff line number Diff line change
Expand Up @@ -4163,7 +4163,7 @@ <h1>
<emu-clause id="sec-reference-record-specification-type" oldids="sec-reference-specification-type">
<h1>The Reference Record Specification Type</h1>
<p>The <dfn variants="Reference Records">Reference Record</dfn> type is used to explain the behaviour of such operators as `delete`, `typeof`, the assignment operators, the `super` keyword and other language features. For example, the left-hand operand of an assignment is expected to produce a Reference Record.</p>
<p>A Reference Record is a resolved name or property binding; its fields are defined by <emu-xref href="#table-reference-record-fields"></emu-xref>.</p>
<p>A Reference Record is a resolved name or (possibly not-yet-resolved) property binding; its fields are defined by <emu-xref href="#table-reference-record-fields"></emu-xref>.</p>

<emu-table id="table-reference-record-fields" caption="Reference Record Fields">
<table>
Expand All @@ -4179,8 +4179,8 @@ <h1>The Reference Record Specification Type</h1>
</tr>
<tr>
<td oldids="sec-getreferencedname,ao-getreferencedname">[[ReferencedName]]</td>
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<td>a String, a Symbol, or a Private Name</td>
<td>The name of the binding. Always a String if [[Base]] value is an Environment Record.</td>
<td>an ECMAScript language value or a Private Name</td>
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I think a sentence of the form "May be an ECMAScript language value [...] until yada yada" would be clearer than "May temporarily be [...]".

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Sounds good; added an Otherwise, to your suggestion to clarify that this just applies to property reference cases.

<td>The name of the binding. Always a String if [[Base]] value is an Environment Record. Otherwise, may be an ECMAScript language value other than a String or a Symbol until ToPropertyKey is performed.</td>
</tr>
<tr>
<td oldids="sec-isstrictreference,ao-isstrictreference">[[Strict]]</td>
Expand Down Expand Up @@ -4265,6 +4265,8 @@ <h1>
1. [id="step-getvalue-toobject"] Let _baseObj_ be ? ToObject(_V_.[[Base]]).
1. If IsPrivateReference(_V_) is *true*, then
1. Return ? PrivateGet(_baseObj_, _V_.[[ReferencedName]]).
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@michaelficarra michaelficarra Apr 22, 2024 •
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Suggested change
1. If _V_.[[ReferencedName]] is neither a String nor a Symbol, then
1. If IsPropertyKey(_V_.[[ReferencedName]]) is *false*, then

Alternatively, I'm not sure why we have that AO instead of just saying "is a property key", since "property key" is a well-defined term. So we could get rid of that AO (as a separate PR) and then just use that phrasing.

Same below for PutValue, of course.

edit: Also evaluation of delete 🤦‍♂️

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Sounds good; opened #3316.

1. If _V_.[[ReferencedName]] is not a property key, then
1. Set _V_.[[ReferencedName]] to ? ToPropertyKey(_V_.[[ReferencedName]]).
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1. Return ? <emu-meta effects="user-code">_baseObj_.[[Get]]</emu-meta>(_V_.[[ReferencedName]], GetThisValue(_V_)).
1. Else,
1. Let _base_ be _V_.[[Base]].
Expand Down Expand Up @@ -4296,6 +4298,8 @@ <h1>
1. [id="step-putvalue-toobject"] Let _baseObj_ be ? ToObject(_V_.[[Base]]).
1. If IsPrivateReference(_V_) is *true*, then
1. Return ? PrivateSet(_baseObj_, _V_.[[ReferencedName]], _W_).
1. If _V_.[[ReferencedName]] is not a property key, then
1. Set _V_.[[ReferencedName]] to ? ToPropertyKey(_V_.[[ReferencedName]]).
1. Let _succeeded_ be ? <emu-meta effects="user-code">_baseObj_.[[Set]]</emu-meta>(_V_.[[ReferencedName]], _W_, GetThisValue(_V_)).
1. If _succeeded_ is *false* and _V_.[[Strict]] is *true*, throw a *TypeError* exception.
1. Return ~unused~.
Expand Down Expand Up @@ -19106,8 +19110,8 @@ <h1>
<emu-alg>
1. Let _propertyNameReference_ be ? Evaluation of _expression_.
1. Let _propertyNameValue_ be ? GetValue(_propertyNameReference_).
1. Let _propertyKey_ be ? ToPropertyKey(_propertyNameValue_).
1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _propertyKey_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
1. NOTE: In most cases, ToPropertyKey will be performed on _propertyNameValue_ immediately after this step. However, in the case of `a[b] = c`, it will not be performed until after evaluation of `c`.
1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _propertyNameValue_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
</emu-alg>
</emu-clause>

Expand Down Expand Up @@ -19239,9 +19243,9 @@ <h1>Runtime Semantics: Evaluation</h1>
1. Let _actualThis_ be ? _env_.GetThisBinding().
1. Let _propertyNameReference_ be ? Evaluation of |Expression|.
1. Let _propertyNameValue_ be ? GetValue(_propertyNameReference_).
1. Let _propertyKey_ be ? ToPropertyKey(_propertyNameValue_).
1. Let _strict_ be IsStrict(this |SuperProperty|).
1. Return ? MakeSuperPropertyReference(_actualThis_, _propertyKey_, _strict_).
1. NOTE: In most cases, ToPropertyKey will be performed on _propertyNameValue_ immediately after this step. However, in the case of `super[b] = c`, it will not be performed until after evaluation of `c`.
1. Return ? MakeSuperPropertyReference(_actualThis_, _propertyNameValue_, _strict_).
</emu-alg>
<emu-grammar>SuperProperty : `super` `.` IdentifierName</emu-grammar>
<emu-alg>
Expand Down Expand Up @@ -19286,7 +19290,7 @@ <h1>GetSuperConstructor ( ): an ECMAScript language value</h1>
<h1>
MakeSuperPropertyReference (
_actualThis_: an ECMAScript language value,
_propertyKey_: a property key,
_propertyKey_: an ECMAScript language value,
_strict_: a Boolean,
): either a normal completion containing a Super Reference Record or a throw completion
</h1>
Expand Down Expand Up @@ -19800,6 +19804,8 @@ <h1>Runtime Semantics: Evaluation</h1>
1. Assert: IsPrivateReference(_ref_) is *false*.
1. If IsSuperReference(_ref_) is *true*, throw a *ReferenceError* exception.
1. [id="step-delete-operator-toobject"] Let _baseObj_ be ? ToObject(_ref_.[[Base]]).
1. If _ref_.[[ReferencedName]] is not a property key, then
1. Set _ref_.[[ReferencedName]] to ? ToPropertyKey(_ref_.[[ReferencedName]]).
1. Let _deleteStatus_ be ? <emu-meta effects="user-code">_baseObj_.[[Delete]]</emu-meta>(_ref_.[[ReferencedName]]).
1. If _deleteStatus_ is *false* and _ref_.[[Strict]] is *true*, throw a *TypeError* exception.
1. Return _deleteStatus_.
Expand Down Expand Up @@ -20460,7 +20466,8 @@ <h1>Runtime Semantics: Evaluation</h1>
1. If |LeftHandSideExpression| is neither an |ObjectLiteral| nor an |ArrayLiteral|, then
1. Let _lref_ be ? Evaluation of |LeftHandSideExpression|.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and IsIdentifierRef of |LeftHandSideExpression| is *true*, then
1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lref_.[[ReferencedName]].
1. Let _lhs_ be the StringValue of |LeftHandSideExpression|.
1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lhs_.
1. Else,
1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
1. Let _rval_ be ? GetValue(_rref_).
Expand Down Expand Up @@ -20509,7 +20516,8 @@ <h1>Runtime Semantics: Evaluation</h1>
1. Let _lbool_ be ToBoolean(_lval_).
1. If _lbool_ is *false*, return _lval_.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and IsIdentifierRef of |LeftHandSideExpression| is *true*, then
1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lref_.[[ReferencedName]].
1. Let _lhs_ be the StringValue of |LeftHandSideExpression|.
1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lhs_.
1. Else,
1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
1. Let _rval_ be ? GetValue(_rref_).
Expand All @@ -20523,7 +20531,8 @@ <h1>Runtime Semantics: Evaluation</h1>
1. Let _lbool_ be ToBoolean(_lval_).
1. If _lbool_ is *true*, return _lval_.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and IsIdentifierRef of |LeftHandSideExpression| is *true*, then
1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lref_.[[ReferencedName]].
1. Let _lhs_ be the StringValue of |LeftHandSideExpression|.
1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lhs_.
1. Else,
1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
1. Let _rval_ be ? GetValue(_rref_).
Expand All @@ -20536,7 +20545,8 @@ <h1>Runtime Semantics: Evaluation</h1>
1. [id="step-assignmentexpression-evaluation-lgcl-nullish-getvalue"] Let _lval_ be ? GetValue(_lref_).
1. If _lval_ is neither *undefined* nor *null*, return _lval_.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and IsIdentifierRef of |LeftHandSideExpression| is *true*, then
1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lref_.[[ReferencedName]].
1. Let _lhs_ be the StringValue of |LeftHandSideExpression|.
1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lhs_.
1. Else,
1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
1. Let _rval_ be ? GetValue(_rref_).
Expand Down Expand Up @@ -20903,7 +20913,8 @@ <h1>
1. Set _value_ to _next_.
1. If |Initializer| is present and _value_ is *undefined*, then
1. If IsAnonymousFunctionDefinition(|Initializer|) is *true* and IsIdentifierRef of |DestructuringAssignmentTarget| is *true*, then
1. Let _v_ be ? NamedEvaluation of |Initializer| with argument _lref_.[[ReferencedName]].
1. Let _target_ be the StringValue of |DestructuringAssignmentTarget|.
1. Let _v_ be ? NamedEvaluation of |Initializer| with argument _target_.
1. Else,
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Let _v_ be ? GetValue(_defaultValue_).
Expand Down Expand Up @@ -20951,7 +20962,8 @@ <h1>
1. Let _v_ be ? GetV(_value_, _propertyName_).
1. If |Initializer| is present and _v_ is *undefined*, then
1. If IsAnonymousFunctionDefinition(|Initializer|) is *true* and IsIdentifierRef of |DestructuringAssignmentTarget| is *true*, then
1. Let _rhsValue_ be ? NamedEvaluation of |Initializer| with argument _lref_.[[ReferencedName]].
1. Let _target_ be the StringValue of |DestructuringAssignmentTarget|.
1. Let _rhsValue_ be ? NamedEvaluation of |Initializer| with argument _target_.
1. Else,
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Let _rhsValue_ be ? GetValue(_defaultValue_).
Expand Down
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