https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896
--- Comment #5 from qinzhao at gcc dot gnu.org ---
(In reply to Jakub Jelinek from comment #3)
> (In reply to Richard Biener from comment #2)
> > Iff only (GNU) C would accept the following ...
> >
> > struct foo {
> > ...
> > unsigned int count;
> > ...
> > int data[count];
> > };
>
> Well, that I think conflicts with the variable length structures GNU
> extension, where
> if the array size of a field isn't a constant expression, it is an
> expression evaluated at runtime once (SAVE_EXPR) to determine the field size.
VLA is only legal inside function scopes.
but this new extension will be legal at file scope.
will this fact be used to distinguish these two?
> Here we are talking about something similar to what Fortran wants with its
> deferred length arrays, essentially to have the size evaluated each time it
> is accessed.
> With the data[count] form even if it would be disambiguated the question is
> if we want to otherwise treat it like normal flexible array member e.g. for
> sizeof etc. and only treat it specially for __bdos, or if it would affect
> say sizeof too.
the immediate purpose of this new extension is used for __bdos.
is there any benefit if it will affect sizeof()?
> I don't see how sizeof (struct foo) could be treated differently from
> flexible array member, because one doesn't have an object on which count can
> be evaluated, but perhaps
> struct foo f;
> f.count = 24;
> sizeof (f.data) could change.
what's the major purpose of enabling this?
