Re: Better diagnostic for shadowed function?

[Jonathan Wakely <jwakely.gcc@gmail.com>]

On Wed, 12 Jan 2022 at 06:34, NightStrike via Gcc-help
<gcc-help@gcc.gnu.org> wrote:
>
> I recently hit this problem:
>
> #include <strings.h>
> void f() {
>     index[0] = 0;
> }
>
> #gcc is 11.2.0
> gcc -c a.c
> a.c:4:7: error: subscripted value is neither array nor pointer nor vector
>     4 |  index[1] = 0;
>       |       ^
>
> -Wshadow (or all or extra) did not highlight that "index" was actually
> a function from strings.h.  For the future, is there anything I could
> have done to make gcc tell me what the real error was?

g++ is *slightly* more help:
s.c:3:10: error: invalid types ‘<unresolved overloaded function
type>[int]’ for array subscript

This at least gives you a hint it's a function, so probably declared
somewhere in a header. The C front end could do the same, saying
"subscripted value is a function", but it just has a generic
diagnostic for all un-subscriptable types. Asking for that to be
improved seems like a good use of a bugzilla PR.

Maybe would make sense for us to also add a note telling you where
'index' was declared, as long as it doesn't get suppressed without
-Wsystem-headers !