Re: [9fans] C compiler question

[Adriano Verardo <a.verardo@tecmav.com>]

erik quanstrom wrote:
>> The point is how to compute the offset(s) of the last field at compile /
>> run time.
>>
>
> the offset of the last field is not in question.  i believe you mean the size?
>
It's really the same info.

struct
{
      .....     // total sizeof = 100
    int B[..];
}A;

offset(B) = 100,  &(A.B[7]) == address(A) + 100 + 7*sizeof(int).
The compiler accept the dirty but legal expression  A.B[-3]  because it
can compute
the address (or the offset with respect the beginnig of "A") of the B
"-3" cell.

But in this case

struct
{
      .....     // total sizeof = 100
    struct B B;
}A;

with B declared (just named), how 8c could determined the address of A.B.x ?
To accept the above definition of A, say in a global .h, means that every .c
should include the definition of B.
They could be - legally - different, so generating different offsets of
"x" with respect A
in the same program.


>> I prefer to have only the tricky but standard  "char  x[0]" tails.
>>
>
> i'd prefer not to have them, either.  but it's too late for that.
>
>
:-)   And what about

char x[...]  and   x[2] == 2[x]    :-)  :-)
>> Your patch will be included in the next distribution CD ?
>>
>
> no.  i haven't submitted it yet.
>
> - erik
adriano