assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(16,5): error TS2322: Type 'new (x: number) => number' is not assignable to type 'new () => number'.
  Target signature provides too few arguments. Expected 1 or more, but got 0.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(17,5): error TS2322: Type 'new (x: number, y?: number | undefined) => number' is not assignable to type 'new () => number'.
  Target signature provides too few arguments. Expected 1 or more, but got 0.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(19,5): error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new () => number'.
  Target signature provides too few arguments. Expected 2 or more, but got 0.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(24,5): error TS2322: Type 'new (x: number) => number' is not assignable to type 'new (x?: number | undefined) => number'.
  Types of parameters 'x' and 'x' are incompatible.
    Type 'number | undefined' is not assignable to type 'number'.
      Type 'undefined' is not assignable to type 'number'.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(25,5): error TS2322: Type 'new (x: number, y?: number | undefined) => number' is not assignable to type 'new (x?: number | undefined) => number'.
  Types of parameters 'x' and 'x' are incompatible.
    Type 'number | undefined' is not assignable to type 'number'.
      Type 'undefined' is not assignable to type 'number'.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(27,5): error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x?: number | undefined) => number'.
  Target signature provides too few arguments. Expected 2 or more, but got 1.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(35,5): error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x: number) => number'.
  Target signature provides too few arguments. Expected 2 or more, but got 1.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(43,5): error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x: number, y?: number | undefined) => number'.
  Types of parameters 'y' and 'y' are incompatible.
    Type 'number | undefined' is not assignable to type 'number'.
      Type 'undefined' is not assignable to type 'number'.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(48,5): error TS2322: Type 'new (x: number) => number' is not assignable to type 'new (x?: number | undefined, y?: number | undefined) => number'.
  Types of parameters 'x' and 'x' are incompatible.
    Type 'number | undefined' is not assignable to type 'number'.
      Type 'undefined' is not assignable to type 'number'.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(49,5): error TS2322: Type 'new (x: number, y?: number | undefined) => number' is not assignable to type 'new (x?: number | undefined, y?: number | undefined) => number'.
  Types of parameters 'x' and 'x' are incompatible.
    Type 'number | undefined' is not assignable to type 'number'.
      Type 'undefined' is not assignable to type 'number'.
assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(51,5): error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x?: number | undefined, y?: number | undefined) => number'.
  Types of parameters 'x' and 'x' are incompatible.
    Type 'number | undefined' is not assignable to type 'number'.
      Type 'undefined' is not assignable to type 'number'.


==== assignmentCompatWithConstructSignaturesWithOptionalParameters.ts (11 errors) ====
    // call signatures in derived types must have the same or fewer optional parameters as the base type
    
    interface Base { 
        a: new () => number;
        a2: new (x?: number) => number;
        a3: new (x: number) => number;
        a4: new (x: number, y?: number) => number;
        a5: new (x?: number, y?: number) => number;
        a6: new (x: number, y: number) => number;
    }
    declare var b: Base;
    
    declare var a: new () => number;
        a = b.a; // ok
        a = b.a2; // ok
        a = b.a3; // error
        ~
!!! error TS2322: Type 'new (x: number) => number' is not assignable to type 'new () => number'.
!!! error TS2322:   Target signature provides too few arguments. Expected 1 or more, but got 0.
        a = b.a4; // error
        ~
!!! error TS2322: Type 'new (x: number, y?: number | undefined) => number' is not assignable to type 'new () => number'.
!!! error TS2322:   Target signature provides too few arguments. Expected 1 or more, but got 0.
        a = b.a5; // ok
        a = b.a6; // error
        ~
!!! error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new () => number'.
!!! error TS2322:   Target signature provides too few arguments. Expected 2 or more, but got 0.
    
    declare var a2: new (x?: number) => number; 
        a2 = b.a; // ok
        a2 = b.a2; // ok
        a2 = b.a3; // ok
        ~~
!!! error TS2322: Type 'new (x: number) => number' is not assignable to type 'new (x?: number | undefined) => number'.
!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
!!! error TS2322:     Type 'number | undefined' is not assignable to type 'number'.
!!! error TS2322:       Type 'undefined' is not assignable to type 'number'.
        a2 = b.a4; // ok
        ~~
!!! error TS2322: Type 'new (x: number, y?: number | undefined) => number' is not assignable to type 'new (x?: number | undefined) => number'.
!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
!!! error TS2322:     Type 'number | undefined' is not assignable to type 'number'.
!!! error TS2322:       Type 'undefined' is not assignable to type 'number'.
        a2 = b.a5; // ok
        a2 = b.a6; // error
        ~~
!!! error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x?: number | undefined) => number'.
!!! error TS2322:   Target signature provides too few arguments. Expected 2 or more, but got 1.
    
    declare var a3: new (x: number) => number; 
        a3 = b.a; // ok
        a3 = b.a2; // ok
        a3 = b.a3; // ok
        a3 = b.a4; // ok
        a3 = b.a5; // ok
        a3 = b.a6; // error
        ~~
!!! error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x: number) => number'.
!!! error TS2322:   Target signature provides too few arguments. Expected 2 or more, but got 1.
    
    declare var a4: new (x: number, y?: number) => number;
        a4 = b.a; // ok
        a4 = b.a2; // ok
        a4 = b.a3; // ok
        a4 = b.a4; // ok
        a4 = b.a5; // ok
        a4 = b.a6; // ok
        ~~
!!! error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x: number, y?: number | undefined) => number'.
!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
!!! error TS2322:     Type 'number | undefined' is not assignable to type 'number'.
!!! error TS2322:       Type 'undefined' is not assignable to type 'number'.
    
    declare var a5: new (x?: number, y?: number) => number;
        a5 = b.a; // ok
        a5 = b.a2; // ok
        a5 = b.a3; // ok
        ~~
!!! error TS2322: Type 'new (x: number) => number' is not assignable to type 'new (x?: number | undefined, y?: number | undefined) => number'.
!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
!!! error TS2322:     Type 'number | undefined' is not assignable to type 'number'.
!!! error TS2322:       Type 'undefined' is not assignable to type 'number'.
        a5 = b.a4; // ok
        ~~
!!! error TS2322: Type 'new (x: number, y?: number | undefined) => number' is not assignable to type 'new (x?: number | undefined, y?: number | undefined) => number'.
!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
!!! error TS2322:     Type 'number | undefined' is not assignable to type 'number'.
!!! error TS2322:       Type 'undefined' is not assignable to type 'number'.
        a5 = b.a5; // ok
        a5 = b.a6; // ok
        ~~
!!! error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x?: number | undefined, y?: number | undefined) => number'.
!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
!!! error TS2322:     Type 'number | undefined' is not assignable to type 'number'.
!!! error TS2322:       Type 'undefined' is not assignable to type 'number'.
    