Hi Richard, On Thu, Oct 16, 2025 at 02:15:59PM +0200, Alejandro Colomar wrote: > On Thu, Oct 16, 2025 at 01:41:40PM +0200, Richard Biener wrote: > > > > If we ever expose vector bools as GNU extension then you get a new > > > > "signed bool" with different _Minof/_Maxof (-1 and 0). > > > > > > > > typedef bool sbool __attribute__((signed_bool_precision(1))); > > > > > > > > _Minof (sbool) == 1 > > > > > > > > need to compile with -fgimple to have the attribute not ignored. And > > > > yes, > > > > a 8-bit precision signed bool is a thing then (but still [-1,0]). > > > > > > What should _Widthof() return for such types? 1? 8? > > > <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3573.txt> > > > > What does _Widthof do to struct { int i : 3; } a.i? Hmm. > > _Widthof() is a constraint violation with non-integer types. > > (And I think I should restrict it to reject booleans too, precisely > because it's not obvious what it should return.)
Ahh, sorry; I misunderstood. You mean _Widthof() of the bit-field
member. _Widthof of a bit-field should return the number of bits in the
bit field. That is...
>
>
> Have a lovely day!
> Alex
>
> > struct { long long x : 37; } x;
> > int main()
> > {
> > __typeof (x.x) a;
..., _Widthof(x.x) == 37
Cheers,
Alex
> > }
> >
> > t4.c:4:13: error: ‘typeof’ applied to a bit-field
> > 4 | __typeof (x.x) a;
> > | ^
> >
> > I see. In GNU C this has long long : 37 type (it isn't promoted).
> > But this works ;)
> > (by accident?)
> >
> > struct { long long x : 37; } x;
> > int main()
> > {
> > auto b = x.x;
> > __typeof (b) c;
> > return c;
> > }
> >
> > > cat t4.c.006t.original
> >
> > ;; Function main (null)
> > ;; enabled by -tree-original
> >
> >
> > {
> > <unnamed-signed:37> b = x.x;
> > <unnamed-signed:37> c;
> >
> > <unnamed-signed:37> b = x.x;
> > <unnamed-signed:37> c;
Nice! :)
--
<https://www.alejandro-colomar.es>
Use port 80 (that is, <...:80/>).
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