==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.ts (6 errors) ====
    // call signatures in derived types must have the same or fewer optional parameters as the target for assignment
    
    module ClassTypeParam {
        class Base<T> {
            a: () => T;
            a2: (x?: T) => T;
            a3: (x: T) => T;
            a4: (x: T, y?: T) => T;
            a5: (x?: T, y?: T) => T;
    
            init = () => {
                this.a = () => null; // ok, same T of required params
                this.a = (x?: T) => null; // ok, same T of required params
                this.a = (x: T) => null; // error, too many required params
                ~~~~~~
!!! Type '(x: T) => any' is not assignable to type '() => T'.
    
                this.a2 = () => null; // ok, same T of required params
                this.a2 = (x?: T) => null; // ok, same T of required params
                this.a2 = (x: T) => null; // ok, same number of params
    
                this.a3 = () => null; // ok, fewer required params
                this.a3 = (x?: T) => null; // ok, fewer required params
                this.a3 = (x: T) => null; // ok, same T of required params
                this.a3 = (x: T, y: T) => null;  // error, too many required params
                ~~~~~~~
!!! Type '(x: T, y: T) => any' is not assignable to type '(x: T) => T'.
    
                this.a4 = () => null; // ok, fewer required params
                this.a4 = (x?: T, y?: T) => null; // ok, fewer required params
                this.a4 = (x: T) => null; // ok, same T of required params
                this.a4 = (x: T, y: T) => null;  // ok, same number of params
    
    
                this.a5 = () => null; // ok, fewer required params
                this.a5 = (x?: T, y?: T) => null; // ok, fewer required params
                this.a5 = (x: T) => null; // ok, all present params match
                this.a5 = (x: T, y: T) => null;  // ok, same number of params
            }
        }
    }
    
    module GenericSignaturesInvalid {
    
        class Base2 {
            a: <T>() => T;
            a2: <T>(x?: T) => T;
            a3: <T>(x: T) => T;
            a4: <T>(x: T, y?: T) => T;
            a5: <T>(x?: T, y?: T) => T;
        }
    
        class Target<T> {
            a: () => T;
            a2: (x?: T) => T;
            a3: (x: T) => T;
            a4: (x: T, y?: T) => T;
            a5: (x?: T, y?: T) => T;
        }
    
    
        function foo<T>() {
            var b: Base2;
            var t: Target<T>;
    
            // all errors
            b.a = t.a;
            b.a = t.a2;
            b.a = t.a3;
            ~~~
!!! Type '(x: T) => T' is not assignable to type '<T>() => T'.
            b.a = t.a4;
            ~~~
!!! Type '(x: T, y?: T) => T' is not assignable to type '<T>() => T'.
            b.a = t.a5;
    
            b.a2 = t.a;
            b.a2 = t.a2;
            b.a2 = t.a3;
            b.a2 = t.a4;
            b.a2 = t.a5;
    
            b.a3 = t.a;
            b.a3 = t.a2;
            b.a3 = t.a3;
            b.a3 = t.a4;
            b.a3 = t.a5;
    
            b.a4 = t.a;
            b.a4 = t.a2;
            b.a4 = t.a3;
            b.a4 = t.a4;
            b.a4 = t.a5;
    
            b.a5 = t.a;
            b.a5 = t.a2;
            b.a5 = t.a3;
            b.a5 = t.a4;
            b.a5 = t.a5;
        }
    }
    
    module GenericSignaturesValid {
    
        class Base2 {
            a: <T>() => T;
            a2: <T>(x?: T) => T;
            a3: <T>(x: T) => T;
            a4: <T>(x: T, y?: T) => T;
            a5: <T>(x?: T, y?: T) => T;
    
            init = () => {
                this.a = <T>() => null; // ok, same T of required params
                this.a = <T>(x?: T) => null; // ok, same T of required params
                this.a = <T>(x: T) => null; // error, too many required params
                ~~~~~~
!!! Type '<T>(x: T) => any' is not assignable to type '<T>() => T'.
    
                this.a2 = <T>() => null; // ok, same T of required params
                this.a2 = <T>(x?: T) => null; // ok, same T of required params
                this.a2 = <T>(x: T) => null; // ok, same number of params
    
                this.a3 = <T>() => null; // ok, fewer required params
                this.a3 = <T>(x?: T) => null; // ok, fewer required params
                this.a3 = <T>(x: T) => null; // ok, same T of required params
                this.a3 = <T>(x: T, y: T) => null;  // error, too many required params
                ~~~~~~~
!!! Type '<T>(x: T, y: T) => any' is not assignable to type '<T>(x: T) => T'.
    
                this.a4 = <T>() => null; // ok, fewer required params
                this.a4 = <T>(x?: T, y?: T) => null; // ok, fewer required params
                this.a4 = <T>(x: T) => null; // ok, same T of required params
                this.a4 = <T>(x: T, y: T) => null;  // ok, same number of params
    
    
                this.a5 = <T>() => null; // ok, fewer required params
                this.a5 = <T>(x?: T, y?: T) => null; // ok, fewer required params
                this.a5 = <T>(x: T) => null; // ok, all present params match
                this.a5 = <T>(x: T, y: T) => null;  // ok, same number of params
            }
        }
    }