https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109956
--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Alexander Monakov from comment #8)
> (In reply to jos...@codesourcery.com from comment #6)
> > For the standard, dynamically allocated case, you should only need to
> > allocate enough memory to contain the initial part of the struct and the
> > array members being accessed - not any padding after that array. (There
> > were wording problems before C99 TC2; see DR#282.)
>
> I think the following testcase indicates that GCC assumes that tail padding
> is accessible:
>
> struct S {
> int i;
> char c;
> char fam[];
> };
>
> void f(struct S *p, struct S *q)
> {
> *p = *q;
> }
>
> f:
> movq (%rsi), %rax
> movq %rax, (%rdi)
> ret
>
> Sorry for the tangential remark, but there seems to be a contradiction.
Not only accessible but also not used by sth else. That is, a following
'char' variable may not be placed into the padding.
