parserMemberAccessorDeclaration17.ts(2,13): error TS1051: A 'set' accessor cannot have an optional parameter.


==== parserMemberAccessorDeclaration17.ts (1 errors) ====
    class C {
       set Foo(a?: number) { }
                ~
!!! error TS1051: A 'set' accessor cannot have an optional parameter.
    }