https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107952
--- Comment #10 from Qing Zhao <qing.zhao at oracle dot com> ---
> --- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
>
> GCC handles for example
>
> struct A { char data[1]; };
> struct B { int n; struct A a; };
>
> as if the a.data[] array is a flex-array.
Okay. Then the maximum size of __builtin_object_size for it should be -1,
right?
> It also handles
>
> struct C { int n; struct A a; int x; };
>
> as if a.data[] can be up to 4 elements large (we allow an array to extend
> flexibly to padding - but only if it is trailing).
A little confused here:
when the structure with a trailing flexible-array member is a middle
field of
an outer structure, GCC extension will treat it as a flexible-array
too? But the
maximum size of this flexible-array will be bounded by the size of the
padding
of that field?
Is the above understanding correct?
> I see that's not
> consistently handled though.
>
> I think the [] syntax should follow the C standard as what testcases are
> accepted/rejected by the frontend and any extensions there should be
> documented
Agreed, usually where these extension should be documented?
> (those are separate from what the former array_at_struct_end_p
> allowed semantically
So, your mean to leave such extension out of “array_at_struct_end_p” (the
current “array_ref_flexible_size_p”)?
Handle them separately instead?
