Many of kvec.h function macros require passing the type being stored (kv_resize, kv_copy, kv_push, kv_pushp, kv_a) but this seems to not actually be needed. It's only used for two reasons:

• To cast the pointer returned from realloc(), which is not actually needed in C where the preferred style is usually to not cast from a void pointer when assigning to a variable.
• In sizeof(type) which could be changed to sizeof(*(v).a)

Has this not been changed simply to not break the current API?