//// [recursiveBaseConstructorCreation1.ts] class C1 { public func(param: C2): any { } } class C2 extends C1 { } var x = new C2(); // Valid //// [recursiveBaseConstructorCreation1.js] var __extends = this.__extends || function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; function __() { this.constructor = d; } __.prototype = b.prototype; d.prototype = new __(); }; var C1 = (function () { function C1() { } C1.prototype.func = function (param) { }; return C1; })(); var C2 = (function (_super) { __extends(C2, _super); function C2() { _super.apply(this, arguments); } return C2; })(C1); var x = new C2(); // Valid