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])
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