Bug 247493

Summary:

Order between initializing x and this.x in strict mode

Product:

WebKit

Reporter:

Kanguk Lee <p51lee>

Component:

JavaScriptCore

Assignee:

Yijia Huang <yijia_huang>

Status:

RESOLVED WONTFIX

Severity:

Normal

CC:

mark.lam, webkit-bug-importer, ysuzuki

Priority:

Keywords:

InRadar

Version:

WebKit Local Build

Hardware:

Mac (Apple Silicon)

OS:

macOS 12

Attachments:

Description	Flags
I captured ECMAScript 2022 section 13.15.2.	none

Kanguk Lee

Reported 2022-11-04 09:59:29 PDT

Created attachment 463411 [details] I captured ECMAScript 2022 section 13.15.2. // input.js "use strict"; x = this.x = 0; ________________________________ Hello, Executing the input.js using JSC terminates normally, but it is expected to throw ReferenceError. According to ECMAScript 2022 section 13.15.2: Evaluation of `*AssignmentExpression* : *LeftHandSideExpression* = *AssignmentExpression*`, (link: https://tc39.es/ecma262/2022/multipage/ecmascript-language-expressions.html#sec-assignment-operators-runtime-semantics-evaluation) in line 1-a, *LeftHandSideExpression*, i.e. `x` should be evaluated first and the evaluation result is an unresolvable reference. Therefore PutValue() in line 1-e throws ReferenceError because strict mode is turned on. WebKit version: 615.1.10

Attachments
I captured ECMAScript 2022 section 13.15.2. (1.28 MB, image/png) 2022-11-04 09:59 PDT, Kanguk Lee	no flags	Details
View All Add attachment proposed patch, testcase, etc.

Radar WebKit Bug Importer

Comment 1 2022-11-07 16:24:45 PST

<rdar://problem/102064848>

Yijia Huang

Comment 2 2022-11-13 00:15:36 PST

Pull request: https://github.com/WebKit/WebKit/pull/6438

Yusuke Suzuki

Comment 3 2022-11-14 11:03:47 PST

Ross pointed out that this is spec issue actually. https://github.com/WebKit/WebKit/pull/6438#issuecomment-1312694884 https://github.com/WebKit/WebKit/pull/6438#issuecomment-1312922522 We close this since the spec will be upgraded.

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