Please describe the problem:
If I declare a callback without the "public" keyword and use it as an argument to a public method, the C code (specifically the header file) will not compile.

Steps to reproduce:
callback void My.Callback (uint j, pointer user_data);
class My.Class {
  public void apply(Callback cb, pointer user_data) { }
}

Actual results:
The C code fails, because the callback is not declared in the header file.

Expected results:
Vala (valac) should fail to compile the above code.

Does this happen every time?
Yes

Other information: