Re: [PATCH c++ 12/12] ada-lang.h: Add cast in GROW_VECT

Pedro Alves
2015-10-26T16:50:44Z

On 10/26/2015 03:49 AM, Simon Marchi wrote:
> The assignment requires a cast in C++.
>
> gdb/ChangeLog:
>
> * ada-lang.h (GROW_VECT): Add cast.
> ---
> gdb/ada-lang.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gdb/ada-lang.h b/gdb/ada-lang.h
> index 62896f1..32c4b55 100644
> --- a/gdb/ada-lang.h
> +++ b/gdb/ada-lang.h
> @@ -147,7 +147,7 @@ struct ada_task_info
> least M objects, updating V and S as necessary. */
>
> #define GROW_VECT(v, s, m) \
> - if ((s) < (m)) (v) = grow_vect (v, &(s), m, sizeof *(v));
> + if ((s) < (m)) (v) = (typeof (v)) grow_vect (v, &(s), m, sizeof *(v));
>

typeof in C is a GCC extension. Probably not all compilers support it.

In my branch I just have:

#define GROW_VECT(v, s, m) \
- if ((s) < (m)) (v) = grow_vect (v, &(s), m, sizeof *(v));
+ if ((s) < (m)) (v) = (char *) grow_vect (v, &(s), m, sizeof *(v));

Because that works for all current uses of GROW_VECT.

If we wanted to make this work for random types, then we could add
a type parameter to the GROW_VECT macro, like:

- #define GROW_VECT(v, s, m) \
- if ((s) < (m)) (v) = grow_vect (v, &(s), m, sizeof *(v));
+ #define GROW_VECT(t, v, s, m) \
+ if ((s) < (m)) (v) = (t *) grow_vect (v, &(s), m, sizeof *(v));

Not sure it's worth it though. It then raises the question of
"why not replace this home grown GROW_VECT stuff with a VEC instead".

Thanks,
Pedro Alves