Bug 217051

When calling "Object.defineProperty" as below, the internal method "[[DefineOwnProperty]" will be invoked. According to ES10.0, when invoking the internal method "[[DefineOwnProperty]]" of the proxy object, the method "defineProperty" of proxy handler is called. So the overwritten property "defineProperty " below is called. And a false will be returned after using "ToBoolean" dealing with its return value, because the method's default return value is undefined. Finally, a TypeError will be thrown as other engines(like V8,spiderMonkey and quickjs) do. But jsc didn't throw any error as my expection, Is there any information I have missed? #### version dbae081 #### command webkit/WebKitBuild/Debug/bin/jsc testcase.js #### testcase function main() { var handler = {defineProperty:function(){ print("overwrite definedProperty"); } }; var target = {"a":3}; var descBefore = Object.getOwnPropertyDescriptor(target,"a"); for(var j in descBefore){ print(j,descBefore[j]); } var p = new Proxy(target,handler); var desc = {value:200}; var v21 = Object.defineProperty(p,"a",desc); print(v21); var descAfter = Object.getOwnPropertyDescriptor(target,"a"); for(var i in descAfter){ print(i,descAfter[i]); } } main(); #### output value 3 writable true enumerable true configurable true overwrite definedProperty [object Object] value 3 writable true enumerable true configurable true #### expected output value 3 writable true enumerable true configurable true overwrite definedProperty TypeError: proxy defineProperty handler returned false for property '"a"' contributor:Yuan Wang