On Mon, Jan 07, 2002 at 11:03:05PM +0000, Nicholas Clark wrote:
> --- include/parrot/parrot.h~ Sat Dec 15 14:21:03 2001
> +++ include/parrot/parrot.h Mon Jan 7 21:56:40 2002
> @@ -68,6 +68,11 @@
> typedef void* BIGINT;
> typedef void* BIGFLOAT;
>
> +/* define a macro to acknowledge an unused argument, and silence a "helpful"
> + compiler warning. gcc will emit a warning on an empty if body unless {} is
> + used to make an empty block. */
> +#define UNUSED(a) if (0 || a) {}
> +
> #include "parrot/global_setup.h"
> #include "parrot/interpreter.h"
> #include "parrot/encoding.h"
> --- ./encodings/singlebyte.c.orig Tue Jan 1 20:35:56 2002
> +++ ./encodings/singlebyte.c Mon Jan 7 22:34:07 2002
> @@ -16,6 +16,8 @@
>
> static UINTVAL
> singlebyte_characters (const void *ptr, UINTVAL bytes) {
> + UNUSED (ptr);
> +
> return bytes;
> }
For gcc, an alternative would be
#define UNUSED(var) __attribute__((unused)) var
static UINTVAL
singlebyte_characters (const void * UNUSED(ptr), UINTVAL bytes) {
return bytes;
}
or even
#define UNUSED __attribute__((unused))
static UINTVAL
singlebyte_characters (const void UNUSED *ptr, UINTVAL bytes) {
return bytes;
}
I just mention it because I'm wondering if with the first version I
gave, you could just do
#define UNUSED(var)
to wipe out variable names. gcc doesn't like that (though it's fine
with it for forward declarations of functions), but I thought maybe it
would appeal more to other compilers. My only complaints with
'if (0 || a) {}' are (1) I can easily see it getting optimized away
and complaining anyway on a later gcc version or different compiler,
and (2) it means you have to put all the UNUSED() after the variable
declarations:
int f(int x, int y) {
int i = x + 1;
float f;
char* s = malloc(256);
UNUSED(y);
/* body */
}
....but it's still the most portable of the alternatives I see, so I
guess it should stay that way in wait of a better idea.
