GitLab

Recently, in PDELab, we have noticed several (not nice) bugs due that some virtual methods have changed to be const without a proper deprecation (See 0cfd4a01). When adding or removing const-ness of a function, you are actually changing the signature of the function and hence, changing the behavior of all of those inheriting and overriding it.

I understand that is an error of the two sides. One for not using a deprecation method after the change, and second because the downstream project was not using the override keyword. But is a simple change here that may save a lot of troubles for all of those that forgot the override keyword.

struct Class {
  // new interface
   virtual void my_function() const // <- const was added
   {
     // similar functionality as non const function before ... 
   }

  // old interface
   DUNE_DEPRECATED virtual void my_function() 
   {
     // forward to the new method
     const_cast<const Class*>(this)->my_function(); 
   }
};