Re: On alignment

[Andrew Haley <aph at redhat dot com>]

Michael Matz writes:

 > On Thu, 20 Mar 2003, Jason Merrill wrote:
 > 
 > > Do people think this bug is worth fixing?  The behavior is rather
 > > surprising, but changing it might break binary compatibility for affected
 > > code--of which there's not likely to be very much, but there could be some.
 > > Code which really wants, say, aligment of 4 for long long could say
 > > __attribute__ ((packed, aligned (4))).  On the other hand, the change would
 > > restore binary compatibility with 2.95 for C code.
 > 
 > This would change e.g the layout of things like:
 > 
 > struct A { int i; };
 > struct B { struct A a; long long int __attribute__((aligned(4))) li; };
 > struct C { struct B b; int j; };
 > 
 > , right?  If yes I think there is not exactly few code which would be
 > broken binary compatibility wise.  I've seen strange things for instance
 > in OpenOffice, where they play with alignments.  And to this end
 > compatibility with 3.x matters more that with 2.95.x.

Well, yes.  But code which reasonably expects a field with alignof == 8 
to be 8-aligned is broken at the present time.

Andrew.