221176 2021-01-30 04:57:08 -0800 An issue about redefining attributes 2021-01-30 09:23:00 -0800 1 1 1 Unclassified WebKit JavaScriptCore WebKit Local Build PC Linux RESOLVED DUPLICATE 38970 P2 Normal --- 1 nisl_grammarly1 webkit-unassigned ashvayka fpizlo ysuzuki oldest_to_newest 1724028 0 nisl_grammarly1 2021-01-30 04:57:08 -0800 #version: d940b47 #Testcase var proto = {}; Object.defineProperty(proto, 'prop', { enumerable: true, }); var Con = function() {}; Con.prototype = proto; var obj = new Con(); Object.defineProperty(obj, 'prop', { enumerable: false, }); var arr = Object.keys(obj); for (var p in obj) { print(1) } #Command: ./webkit/WebKitBuild/Release/bin/jsc testcase.js #Output: 1 #Expected output: # Description When executing this test case, the prop property of obj was redefined, and other engines (SpiderMonkey, v8, chakra, etc.) set it as the redefined property, but the property of JavascriptCore is still the property on the prototype. So I suspect this is an implementation error of JavascriptCore. 1724035 1 ashvayka 2021-01-30 09:23:00 -0800 (In reply to NWU_NISL from comment #0) > # Description > When executing this test case, the prop property of obj was redefined, and > other engines (SpiderMonkey, v8, chakra, etc.) set it as the redefined > property, but the property of JavascriptCore is still the property on the > prototype. So I suspect this is an implementation error of JavascriptCore. Thank you for the test case! It was a long-standing issue, but as of r270874, JSC doesn't enumerate "prop" either. *** This bug has been marked as a duplicate of bug 38970 ***