==== tests/cases/compiler/typeIdentityConsidersBrands.ts (2 errors) ====
    class X{
          name: string;
    }
    
    class Y{
          name: string;
    }
    
    class X_1 {
        private name: string;
    }
    
    class Y_1 {
        private name: string;
    }
    
    function foo(arg: X){}
     
    var a = new Y();
    var b = new X();
     
    a = b; // ok
    foo(a); // ok
    
    var a2 = new Y_1();
    var b2 = new X_1();
    
    function foo2(arg: X_1) { }
    
    a2 = b2; // should error
    ~~
!!! Type 'X_1' is not assignable to type 'Y_1':
!!!   Private property 'name' cannot be reimplemented.
    foo2(a2); // should error
         ~~
!!! Argument of type 'Y_1' is not assignable to parameter of type 'X_1'.