Re: Alignment Issues with *ManagedStruct?

[Leopold Toetsch]

Chromatic <[EMAIL PROTECTED]> wrote:

[ align issues ]

Nested structs are ugly. The alignment of the first item seems to depend
on the biggest item in the struct.

   struct {
     char          // 0
     struct {
       char        // 1
     }
     char          // 2
   }

   struct {
     char          // 0
     struct {
       char        // 4
       int         // 8
     }
   }

So we need some notion of nested structs or a hint for correct
alignment. I've checked in basic alignment handling for "normal"
cases, but not the second one above.

Below is a test program to experiment with that stuff.

leo


#include <stdlib.h>
#include <stddef.h>
#include <stdio.h>

// offsetof expands to ((size_t) &(( struct xt  *)0)->  x )

struct xt {
        char x;
        struct yt {
                char i;
                int  j;   // use different items here
        } _y;
        char z;
} _x;

int main(void) {
        printf("x : %d\n", offsetof(struct xt, x));
        printf("i : %d\n", offsetof(struct xt, _y.i));
        printf("j : %d\n", offsetof(struct xt, _y.j));
        printf("z : %d\n", offsetof(struct xt, z));
        return 0;
}