interface I1 { IM1():void[]; } class C1 implements I1 { IM1():void[] {return null;} C1M1():C1[] {return null;} } class C2 extends C1 { C2M1():C2[] { return null;} } class C3 { CM3M1() { return 3;} } /* This behaves unexpectedly with the following types: Type 1 of any[]: * Type 2 of the following throws an error but shouldn't: () => void[], SomeClass[], and {one: 1}[]. * Type 2 of the following doesn't throw an error but should: {one: 1}, new() => SomeClass, SomeClass. */ var a1 : any = null; var c1 : C1 = new C1(); var i1 : I1 = c1; var c2 : C2 = new C2(); var c3 : C3 = new C3(); var o1 = {one : 1}; var f1 = function () { return new C1();} var arr_any: any[] = []; var arr_i1: I1[] = []; var arr_c1: C1[] = []; var arr_c2: C2[] = []; var arr_i1_2: I1[] = []; var arr_c1_2: C1[] = []; var arr_c2_2: C2[] = []; var arr_c3: C3[] = []; // "clean up error" occurs at this point arr_c3 = arr_c2_2; // should be an error - is arr_c3 = arr_c1_2; // should be an error - is arr_c3 = arr_i1_2; // should be an error - is arr_any = f1; // should be an error - is arr_any = function () { return null;} // should be an error - is arr_any = o1; // should be an error - is arr_any = a1; // should be ok - is arr_any = c1; // should be an error - is arr_any = c2; // should be an error - is arr_any = c3; // should be an error - is arr_any = i1; // should be an error - is