Bug 231041

Summary: [JSC] DateTimeFormat.resolvedOptions shouldn't return an object with other date/time properties if dateStyle or timeStyle are set
Product: WebKit Reporter: Philip Chimento <philip.chimento>
Component: JavaScriptCoreAssignee: Yusuke Suzuki <ysuzuki>
Status: RESOLVED FIXED    
Severity: Normal CC: ews-watchlist, fpizlo, keith_miller, kevin_neal, mark.lam, msaboff, philip.chimento, ross.kirsling, saam, tzagallo, webkit-bug-importer, ysuzuki
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Patch none

Description Philip Chimento 2021-09-30 15:57:13 PDT 
According to the specification for Intl.DateTimeFormat.prototype.resolvedOptions() (https://tc39.es/ecma402/#sec-intl.datetimeformat.prototype.resolvedoptions) step 5.d, none of the properties in Table 4 (weekday, era, year, month, day, dayPeriod, hour, minute, second, fractionalSecondDigits, timeZoneName) should be present on the returned object if dateStyle or timeStyle are present. JavaScriptCore currently does not implement this step correctly:

> new Intl.DateTimeFormat('en', {dateStyle:'short'}).resolvedOptions().year
"2-digit"

This means you currently cannot always pass the object returned from resolvedOptions() back into the DateTimeFormat constructor as the options argument, for one thing.
Comment 1 Kevin Neal 2021-10-01 14:31:12 PDT 
Thank you for filing. The appropriate engineers have been notified.
Comment 2 Radar WebKit Bug Importer 2021-10-01 14:31:27 PDT 
<rdar://problem/83782481>
Comment 3 Yusuke Suzuki 2021-10-02 14:51:22 PDT 
Created attachment 439973 [details]
Patch
Comment 4 Ross Kirsling 2021-10-02 16:33:21 PDT 
Comment on attachment 439973 [details]
Patch

r=me, but we should make sure this gets captured in test262.
Comment 5 EWS 2021-10-02 19:13:26 PDT 
Committed r283460 (242439@main): <https://commits.webkit.org/242439@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 439973 [details].