Evan Jones <evanj@xxxxxxx> writes:
> It is easy enough to work around this warning by assigning to void*
> first. However, why does GCC think that struct sockaddr and struct
> sockaddr_in have different alignment requirements? They are both 16
> bytes long. If you create an array of the two types, the elements are
> packed without any padding. Thus, it seems like GCC thinks they have
> the *same* alignment requirements in arrays, but different
> requirements in pointers? I don't get it. Is this a bug?
The size of the type does not describe the required alignment of the
type. If, say, struct sockaddr is defined as { char x[16]; } then the
size is 16 but it may be aligned on any 8-bit boundary. If, say, struct
sockaddr_in has fields of type short or int, then the size may be 16 but
it may require alignment on a 16-bit or 32-bit boundary. The same
applies to an array of these types: an array of sockaddr may require
8-bit alignment while an array of sockaddr_in may require 32-bit
alignment, independently of the overall size of the array.
I don't know what the actual definitions of these structs are on your
system.
Ian
