I "abuse" unions and anonymous unions all the time, it's very practical, and make the 'user' code a lot clearer as you can access the small 'namespace' as convenient. Here for example I can access it as named coordinates, x,y points or a vector.

   typedef union c2_rect_t {
     struct {
        c2_pt_t tl, br;
     };
     c2_coord_t v[4];
     struct {
       c2_coord_t l,t,r,b;
     };
   } c2_rect_t;