RESOLVED FIXED 253634
[JSC] Bound function optimization is observable with instanceof 
https://bugs.webkit.org/show_bug.cgi?id=253634
Summary [JSC] Bound function optimization is observable with instanceof
Jan de Mooij
Reported 2023-03-09 00:19:31 PST
Created attachment 465371 [details] Test When binding an already-bound function, JSC tries to flatten this chain. This optimization is observable with `instanceof` because it gets the bound function's immediate target and does a `Symbol.hasInstance` lookup on it. See the attached testcase. It should alert 10000 but I get 0 with Safari Technology Preview 165.
Attachments
Test (339 bytes, text/html)
2023-03-09 00:19 PST, Jan de Mooij 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2023-03-09 06:37:30 PST
<rdar://problem/106498460>
Yusuke Suzuki
Comment 2 2023-03-10 14:57:22 PST
Pull request: https://github.com/WebKit/WebKit/pull/11385
Note You need to log in before you can comment on or make changes to this bug.