Hi Martin, On Sun, Aug 04, 2024 at 06:43:46PM GMT, Alejandro Colomar wrote: > On Sun, Aug 04, 2024 at 06:40:14PM GMT, Alejandro Colomar wrote: > > > The last > > > case should return a non-constant. > > > > The last case [*] is only allowed in prototypes. How should we get the > > non-constant value? It's just another way to say [], isn't it? > > > > > If you reuse the sizeof code, it should be mostly correct, but > > > maybe the last case needs to be revisted. In the following > > > examples > > > > > > void foo(char (*a)[3][*], int (*x)[__lengthof__(*a)]); > > > void bar(char (*a)[*][3], int (*x)[__lengthof__(*a)]); > > > > > > the array '*x' should be a regular fixed size array in foo > > > but a VLA in 'bar'. > > > > In the function prototype, it seems to be completely ignoring > > __lengthof__, just as it ignores any expression, so I don't know if it's > > working (I could try to print some debugging values to stderr from the > > compiler, if we care about it). > > Huh, no, my bad. It must be using the lengthof value. It needs to > match pointers to arrays of a given size. I'll test this.
Is this missing diagnostics?
$ cat star.c
void foo(char (*a)[3][*], int (*x)[__lengthof__(*a)]);
void bar(char (*a)[*][3], int (*x)[__lengthof__(*a)]);
void foos(char (*a)[3][*], int (*x)[sizeof(*a)]);
void bars(char (*a)[*][3], int (*x)[sizeof(*a)]);
int
main(void)
{
int i3[3];
int i5[5];
char c35[3][5];
char c53[5][3];
foo(&c35, &i3);
foo(&c35, &i5); // I'd expect this to fail
bar(&c53, &i3); // I'd expect this to fail
bar(&c53, &i5);
foos(&c35, &i3);
foos(&c35, &i5); // I'd expect this to fail
bars(&c53, &i3); // I'd expect this to fail
bars(&c53, &i5);
}
$ /opt/local/gnu/gcc/lengthof/bin/gcc -Wall -Wextra star.c -S
$
Cheers,
Alex
>
> >
> > $ cat muecker.h
> > void foo(char (*a)[3][*], int (*x)[__lengthof__(*a)]);
> > void bar(char (*a)[*][3], int (*x)[__lengthof__(*a)]);
> > void f(char (*a)[3][*], int (*x)[sizeof(*a)]);
> > void b(char (*a)[*][3], int (*x)[sizeof(*a)]);
> > $ /opt/local/gnu/gcc/lengthof/bin/gcc muecker.h -S
> > $
> >
> > I assume the code above is not reaching my code.
>
> --
> <https://www.alejandro-colomar.es/>
--
<https://www.alejandro-colomar.es/>
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