method({int a = 42, required int b, required int c}) {}

class Class {
  method({int a = 42, required int b, required covariant int c}) {}
}

typedef Typedef1 = Function({int a, required int b});

typedef Typedef2({int a, required int b});

Function({int a, required int b}) field = ({int a = 42, required int b}) {};

abstract class A {
  foo({int x});
}

class B extends A {
  foo({x}) {}
}

class C extends A {
  foo({x = 42}) {}
}

ok() {}

error() {}

main() {}