* Paolo Bonzini: >> Additional members are permitted, and the fields can be order. In >> order to create a portable Ada interface, I have to write a short C >> program which uses sizeof and offsetof to extract the structure >> layout. In theory, it is possible to create compile-time-only tests >> suitable for cross-compilation (compile-time constant expressions, >> invalid zero-length arrays, and a binary search), but this is rather >> messy. > > Look at AC_COMPUTE_INT.
This is exactly the thing I'm scared of. 8-) > It should be easy to start from there and do a macro like > > GCC_COMPUTE_MEMBERS_SIZE_OFFSET([#include <poll.h>], > [struct pollfd], > [fd events revents]). If we'd use such a macro to extract values of various E* constants, bootstrap times would increase significantly, even while not cross-compiling. That's why I think it's not a viable approach.
