assignment_to_final_no_setter

There isn't a setter named '{0}' in class '{1}'.

The analyzer produces this diagnostic when a reference to a setter is found; there is no setter defined for the type; but there is a getter defined with the same name.

The following code produces this diagnostic because there is no setter named x in C, but there is a getter named x:

class C {
  int get x => 0;
  set y(int p) {}
}

void f(C c) {
  c.x = 1;
}

If you want to invoke an existing setter, then correct the name:

class C {
  int get x => 0;
  set y(int p) {}
}

void f(C c) {
  c.y = 1;
}

If you want to invoke the setter but it just doesn't exist yet, then declare it:

class C {
  int get x => 0;
  set x(int p) {}
  set y(int p) {}
}

void f(C c) {
  c.x = 1;
}