[Freeciv-Dev] Re: contains_special type safe?

[Jason Dorje Short <jdorje@xxxxxxxxxxxx>]

Mike Kaufman wrote:
> /***************************************************************
>  Returns TRUE iff the given special is found in the given set.
> ***************************************************************/
> bool contains_special(enum tile_special_type set,
>                       enum tile_special_type to_test_for)
> {
>   enum tile_special_type masked = set & to_test_for;
>
>   assert(0 == (int) S_NO_SPECIAL);
>
>   /*
>    * contains_special should only be called with one S_* in
>    * to_test_for.
>    */
>   assert(masked == S_NO_SPECIAL || masked == to_test_for);
>
>   return masked == to_test_for;
> }
>
> surely this can't be correct: enum tile_special_type set is in general not
> an enum tile_special_type...
True, but this kind of thing is common.  The most obvious alternative is 
using an int for the 'set' but this is just as bad.  A typedef is 
possible (typedef int special_set) but not much better.
The only "good" alternative is a BV_DEFINE.  This would mean changing 
the enum so it's no longer a bitmask and making the "set" a bitvector.
jason