In the following script, the last comparison r = new RegExp; r2 = new RegExp(r); r == r2; should produce false; however, with JSC it produces true. I.e., the "copy-constructing" call to RegExp doesn't return a new object. In both V8 and SpiderMonkey, a new object is returned, as per ECMA-262 5th edition, section 15.10.4.
Created attachment 98947 [details] Thepatch
Attachment 98947 [details] did not pass style-queue: Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'LayoutTests/ChangeLog', u'LayoutTests/fast..." exit_code: 1 Source/JavaScriptCore/runtime/RegExpConstructor.cpp:305: An else statement can be removed when the prior "if" concludes with a return, break, continue or goto statement. [readability/control_flow] [4] Total errors found: 1 in 7 files If any of these errors are false positives, please file a bug against check-webkit-style.
fixed in r89946