==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithObjectMembersOptionality.ts (6 errors) ====
    // Derived member is not optional but base member is, should be ok
    
    class Base { foo: string; }
    class Derived extends Base { bar: string; }
    class Derived2 extends Derived { baz: string; }
    
    module TargetHasOptional {
        // targets
        interface C {
            opt?: Base
        }
        var c: C;
    
        var a: { opt?: Base; }
        var b: typeof a = { opt: new Base() }
    
        // sources
        interface D {
            opt: Base;
        }
        interface E {
            opt: Derived;
        }
        interface F {
            opt?: Derived;
        }
        var d: D;
        var e: E;
        var f: F;
    
        // all ok
        c = d;
        c = e;
        c = f;
        c = a;
    
        a = d;
        a = e;
        a = f;
        a = c;
    
        b = d;
        b = e;
        b = f;
        b = a;
        b = c;
    }
    
    module SourceHasOptional {
        // targets
        interface C {
            opt: Base
        }
        var c: C;
    
        var a: { opt: Base; }
        var b = { opt: new Base() }
    
        // sources
        interface D {
            opt?: Base;
        }
        interface E {
            opt?: Derived;
        }
        interface F {
            opt: Derived;
        }
        var d: D;
        var e: E;
        var f: F;
    
        c = d; // error
        ~
!!! Type 'D' is not assignable to type 'C':
!!!   Required property 'opt' cannot be reimplemented with optional property in 'D'.
        c = e; // error
        ~
!!! Type 'E' is not assignable to type 'C':
!!!   Required property 'opt' cannot be reimplemented with optional property in 'E'.
        c = f; // ok
        c = a; // ok
    
        a = d; // error
        ~
!!! Type 'D' is not assignable to type '{ opt: Base; }':
!!!   Required property 'opt' cannot be reimplemented with optional property in 'D'.
        a = e; // error
        ~
!!! Type 'E' is not assignable to type '{ opt: Base; }':
!!!   Required property 'opt' cannot be reimplemented with optional property in 'E'.
        a = f; // ok
        a = c; // ok
    
        b = d; // error
        ~
!!! Type 'D' is not assignable to type '{ opt: Base; }':
!!!   Required property 'opt' cannot be reimplemented with optional property in 'D'.
        b = e; // error
        ~
!!! Type 'E' is not assignable to type '{ opt: Base; }':
!!!   Required property 'opt' cannot be reimplemented with optional property in 'E'.
        b = f; // ok
        b = a; // ok
        b = c; // ok
    }