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var BUGNUMBER = 1287520;
var summary = 'Array.prototype.concat should check HasProperty everytime for non-dense array';
print(BUGNUMBER + ": " + summary);
var a = [1, 2, 3];
a.constructor = {
[Symbol.species]: function(...args) {
var p = new Proxy(new Array(...args), {
defineProperty(target, propertyKey, receiver) {
if (propertyKey === "0") delete a[1];
return Reflect.defineProperty(target, propertyKey, receiver);
}
});
return p;
}
};
var p = a.concat();
assertEq(0 in p, true);
assertEq(1 in p, false);
assertEq(2 in p, true);
if (typeof reportCompare === "function")
reportCompare(true, true);