On 05/01/11 09:03, Jim Meyering wrote:
> PÃdraig Brady wrote:
> ...
>>>> Perhaps this might work?
>>>>
>>>> static inline void _ignore (int i) { (void) i; }
>>>> #define ignore(x) _ignore ((int)x)
>>>
>>> I don't think so, it will produce warnings about cast from pointer to
>>> integer if the function (foo() in my example) returns a pointer.
>>
>> Ah right, there would be a warning when the pointer
>> size is different to the int. So this would be better:
>>
>> #include <stdint.h>
>> static inline void _ignore (intptr_t p) { (void) p; }
>> #define ignore(x) _ignore ((intptr_t)x)
>
> Nice.
> That works for me, as a plug-in replacement for gnulib's ignore-value.h:
>
> #include <stdint.h>
> static inline void _ignore_value (intptr_t p) { (void) p; }
> #define ignore_value(x) _ignore_value ((intptr_t) x)
>
> /* ignore_value now works for both scalars and pointers, so deprecate. */
> static inline void __attribute__((__deprecated__))
> ignore_ptr (void* p) { (void) p; } /* deprecated: use ignore_value */
>
> i.e., with the above (and a few s/ignore_ptr/ignore_value/),
> coreutils still compiles warning-free.
>
> I opted to stick with ignore_value, since the name "ignore" is
> probably too common to usurp like that. For example, while it
> doesn't conflict per se, sort.c does have both a local variable and
> a struct member named "ignore".
>
> The only drawback (probably acceptable) is that
> it adds a dependency on <stdint.h>.
>
>> But that still doesn't work for aggregate types.
>
> That's ok. Those are far less common.
>
> ------------------------------------------------
> Here's the gnulib patch:
>
> diff --git a/lib/ignore-value.h b/lib/ignore-value.h
> index 04d6520..7e5ae3a 100644
> --- a/lib/ignore-value.h
> +++ b/lib/ignore-value.h
> @@ -35,8 +35,14 @@
> #ifndef _GL_IGNORE_VALUE_H
> # define _GL_IGNORE_VALUE_H
>
> -static inline void ignore_value (int i) { (void) i; }
> -static inline void ignore_ptr (void* p) { (void) p; }
> +#include <stdint.h>
> +static inline void _ignore_value (intptr_t p) { (void) p; }
> +#define ignore_value(x) _ignore_value ((intptr_t) x)
> +
> +/* ignore_value now works for both scalars and pointers, so deprecate. */
> +static inline void __attribute__((__deprecated__))
> +ignore_ptr (void* p) { (void) p; } /* deprecated: use ignore_value */
> +
> /* FIXME: what about aggregate types? */
>
> #endif
> diff --git a/modules/ignore-value b/modules/ignore-value
> index 8d48863..aeda194 100644
> --- a/modules/ignore-value
> +++ b/modules/ignore-value
> @@ -5,6 +5,7 @@ Files:
> lib/ignore-value.h
>
> Depends-on:
> +stdint
>
> configure.ac:
> AC_REQUIRE([AC_C_INLINE])
>
Cool, thanks for doing that.
It probably needs this too:
#ifndef __attribute__
/* The __attribute__((__deprecated__) feature
is available in gcc versions 3.1 and later. */
# if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 1)
# define __attribute__(Spec) /* empty */
# endif
#endif
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