[Bug c/120901] missing diagnostics about jump into scope after defining of a VLA struct

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120901

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> Note with -O2 -W -Wall we do get an uninitialized variable warning even:
> 
> <source>:8:18: warning: 'argc.0' is used uninitialized [-Wuninitialized]
>     8 |         struct c a;
>       |                  ^
> <source>:6:9: note: 'argc.0' was declared here
>     6 |         };
>       |         ^

That is with:
```

int main(int argc, char *argv[]) {
        goto lab;
        struct c {
          int a[argc];
        };
lab:    ;
        struct c a;
        return sizeof(a);
}
```