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

[Pedro Alves <palves at redhat dot com>]

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