On Tue, 5 Oct 2021 20:28:54 +0200 (CEST)
Jan Engelhardt <jengelh@xxxxxxx> wrote:
> On Tuesday 2021-10-05 20:06, Mathieu Desnoyers wrote:
> >> instead of just "typeof(p)", to force the decay to a pointer.
> >
> >If the type of @p is an integer, (p) + 0 is still valid, so it will not
> >prevent users from passing an integer type as argument, which is what
> >the current implementation prevents.
> >
> >Also, AFAIU, the compiler wants to know the sizeof(p) in order to evaluate
> >(p + 0). Steven's goal is to hide the structure declaration, so that would
> >not work either.
>
> >>>> typeof(*p) *________p1 = (typeof(*p) *__force)READ_ONCE(p);
>
>
> #define static_cast(type, expr) ((struct { type x; }){(expr)}.x)
> typeof(p) p1 = (typeof(p) __force)static_cast(void *, READ_ONCE(p));
>
> Let the name not fool you; it's absolutely _not_ the same as C++'s
> static_cast, but still: it does emit a warning when you do pass an
> integer, which is better than no warning at all in that case.
>
> *flies away*
Are you suggesting I should continue this exercise ;-)
-- Steve
