Bug 165227

Summary: Introduce the concept of Immutable Prototype Exotic Objects to comply with the spec.
Product: WebKit Reporter: Mark Lam <mark.lam>
Component: JavaScriptCoreAssignee: Mark Lam <mark.lam>
Status: RESOLVED FIXED    
Severity: Normal CC: cdumez, commit-queue, dbates, esprehn+autocc, fpizlo, ggaren, jfbastien, kangil.han, keith_miller, kondapallykalyan, msaboff, saam, webkit-bug-importer, ysuzuki
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
proposed patch. saam: review+

Attachments
proposed patch. (49.43 KB, patch)
2016-12-05 20:01 PST, Mark Lam 		saam: review+
DetailsFormatted DiffDiff
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Mark Lam
Comment 1 2016-11-30 16:16:27 PST
<rdar://problem/29442665>
Mark Lam
Comment 2 2016-12-05 12:29:58 PST
Spec excerpts of relevance: https://tc39.github.io/ecma262/#sec-properties-of-the-object-prototype-object "The Object prototype object is an immutable prototype exotic object." https://html.spec.whatwg.org/#the-windowproxy-exotic-object https://html.spec.whatwg.org/#windowproxy-setprototypeof https://html.spec.whatwg.org/#the-location-interface https://html.spec.whatwg.org/#location-setprototypeof - Based on these WindowProxy and Location both have their [[SetPrototypeOf]] functions unconditionally return false. This differs from the immutable prototype exotic object which allows [[SetPrototypeOf]] to return true if the set value is the same as the existing prototype value.
Mark Lam
Comment 3 2016-12-05 20:01:06 PST
Created attachment 296251 [details] proposed patch.
Saam Barati
Comment 4 2016-12-06 14:37:41 PST
Comment on attachment 296251 [details] proposed patch. View in context: https://bugs.webkit.org/attachment.cgi?id=296251&action=review r=me > LayoutTests/js/script-tests/prototype-assignment.js:36 > + let userAgent = navigator.userAgent; > + if (userAgent.match(/ Chrome\/[0-9]+/)) engine = "chrome"; > + else if (userAgent.match(/ Firefox\/[0-9]+/)) engine = "default"; > + else engine = "safari"; What's the point of this? Don't we already know the answer?
Mark Lam
Comment 5 2016-12-06 14:39:43 PST
Comment on attachment 296251 [details] proposed patch. View in context: https://bugs.webkit.org/attachment.cgi?id=296251&action=review >> LayoutTests/js/script-tests/prototype-assignment.js:36 >> + else engine = "safari"; > > What's the point of this? Don't we already know the answer? This is so I can run this test on Chrome and Firefox to compare results. The test configures the error messages to check below based on the browser it is running on.
Mark Lam
Comment 6 2016-12-06 14:44:20 PST
Thanks for the review. Landed in r209424: <http://trac.webkit.org/r209424>.
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