Nathan Sidwell wrote:
> Mark Mitchell wrote:
>
>> struct Foo { void operator=(Foo const &);};
>> struct Baz __attribute__((packed))
>> {
>> char c;
>> Foo m;
>> }
>>
>> void Bar (Baz *ptr)
>> {
>> ptr->m = something;
>> }
>>
>> I'm not sure it can be made to work, without making the base class
>> version of Foo::operator= expect unaligned input, which seems an
>> unreasonable pessimization. I would expect this code to be invalid, and
>> either issue a diagnostic, or at least be considered undefined behavior.
>
>
> It can be made to work by not packing Baz::m, and that is what g++ does
> (with a warning%).
Ah! That makes sense.
> % ah, I think that warning should only be given on non-default-packed
> arches. Is this your problem Jan?
I think the warning should be given only if the base class does not
itself have the minimum alignment for the artchitecture. (So that you
would get the warning on a system that was packed by default if you used
a base class which was explicitly aligned on a wider boundary.)
--
Mark Mitchell
CodeSourcery, LLC
[EMAIL PROTECTED]
(916) 791-8304
