Silence -Wpointer-to-int-cast warnings in newlib/libc/string/local.h.
Commit Message
Compiling the library for a 16-bit target results in numerous warnings
(some of which are shown below) in the mem*, str*, and several other
functions. The existing code incorrectly assumes that pointers are 32
bits wide. This patch removes that assumption and fixes the resulting
warnings.
[...]
CC libc/string/libc_a-memchr.o
In file included from ../../../../../../../newlib/newlib/libc/string/memchr.c:35:
../../../../../../../newlib/newlib/libc/string/memchr.c: In function 'memchr':
../../../../../../../newlib/newlib/libc/string/local.h:24:25: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
24 | #define UNALIGNED_X(X) ((long)(X) & (sizeof (long) - 1))
| ^
../../../../../../../newlib/newlib/libc/string/memchr.c:50:10: note: in expansion of macro 'UNALIGNED_X'
50 | while (UNALIGNED_X(src))
| ^~~~~~~~~~~
CC libc/string/libc_a-memcmp.o
In file included from ../../../../../../../newlib/newlib/libc/string/memcmp.c:33:
../../../../../../../newlib/newlib/libc/string/memcmp.c: In function 'memcmp':
../../../../../../../newlib/newlib/libc/string/local.h:33:5: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
33 | (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
| ^
../../../../../../../newlib/newlib/libc/string/memcmp.c:63:38: note: in expansion of macro 'UNALIGNED_X_Y'
63 | if (!TOO_SMALL_LITTLE_BLOCK(n) && !UNALIGNED_X_Y(s1,s2))
| ^~~~~~~~~~~~~
../../../../../../../newlib/newlib/libc/string/local.h:33:39: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
33 | (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
| ^
../../../../../../../newlib/newlib/libc/string/memcmp.c:63:38: note: in expansion of macro 'UNALIGNED_X_Y'
63 | if (!TOO_SMALL_LITTLE_BLOCK(n) && !UNALIGNED_X_Y(s1,s2))
| ^~~~~~~~~~~~~
[...]
Signed-off-by: Jan Dubiec <jdx@o2.pl>
---
newlib/libc/string/local.h | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
Comments
Hi Jan,
The fallback for intptr_t is unnecessary. According to
libc/include/sys/_intsup.h, gcc 3.2 or higher should support
the intptr info we need plus there is an #error statement if it isn't. So,
the code should just use intptr_t.
-- Jeff J.
On Thu, Jul 16, 2026 at 7:40 PM Jan Dubiec <jdx@o2.pl> wrote:
> Compiling the library for a 16-bit target results in numerous warnings
> (some of which are shown below) in the mem*, str*, and several other
> functions. The existing code incorrectly assumes that pointers are 32
> bits wide. This patch removes that assumption and fixes the resulting
> warnings.
>
> [...]
> CC libc/string/libc_a-memchr.o
> In file included from
> ../../../../../../../newlib/newlib/libc/string/memchr.c:35:
> ../../../../../../../newlib/newlib/libc/string/memchr.c: In function
> 'memchr':
> ../../../../../../../newlib/newlib/libc/string/local.h:24:25: warning:
> cast from pointer to integer of different size [-Wpointer-to-int-cast]
> 24 | #define UNALIGNED_X(X) ((long)(X) & (sizeof (long) - 1))
> | ^
> ../../../../../../../newlib/newlib/libc/string/memchr.c:50:10: note: in
> expansion of macro 'UNALIGNED_X'
> 50 | while (UNALIGNED_X(src))
> | ^~~~~~~~~~~
> CC libc/string/libc_a-memcmp.o
> In file included from
> ../../../../../../../newlib/newlib/libc/string/memcmp.c:33:
> ../../../../../../../newlib/newlib/libc/string/memcmp.c: In function
> 'memcmp':
> ../../../../../../../newlib/newlib/libc/string/local.h:33:5: warning: cast
> from pointer to integer of different size [-Wpointer-to-int-cast]
> 33 | (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) -
> 1)))
> | ^
> ../../../../../../../newlib/newlib/libc/string/memcmp.c:63:38: note: in
> expansion of macro 'UNALIGNED_X_Y'
> 63 | if (!TOO_SMALL_LITTLE_BLOCK(n) && !UNALIGNED_X_Y(s1,s2))
> | ^~~~~~~~~~~~~
> ../../../../../../../newlib/newlib/libc/string/local.h:33:39: warning:
> cast from pointer to integer of different size [-Wpointer-to-int-cast]
> 33 | (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) -
> 1)))
> | ^
> ../../../../../../../newlib/newlib/libc/string/memcmp.c:63:38: note: in
> expansion of macro 'UNALIGNED_X_Y'
> 63 | if (!TOO_SMALL_LITTLE_BLOCK(n) && !UNALIGNED_X_Y(s1,s2))
> | ^~~~~~~~~~~~~
> [...]
>
> Signed-off-by: Jan Dubiec <jdx@o2.pl>
> ---
> newlib/libc/string/local.h | 19 +++++++++++++++++--
> 1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/newlib/libc/string/local.h b/newlib/libc/string/local.h
> index 012a30d16..79436ab69 100644
> --- a/newlib/libc/string/local.h
> +++ b/newlib/libc/string/local.h
> @@ -1,5 +1,6 @@
> #include <_ansi.h>
> #include <../ctype/local.h>
> +#include <stdint.h>
>
> /* internal function to compute width of wide char. */
> int __wcwidth (wint_t);
> @@ -17,11 +18,24 @@ int __wcwidth (wint_t);
> # define __inhibit_loop_to_libcall
> #endif
>
> +#ifdef __INTPTR_TYPE__
> + #define INTPTRTYPE intptr_t
> +#else
> + /* Fallback, just in case there is no intptr_t on a target... */
> + #if __SIZEOF_POINTER__ > __SIZEOF_SHORT__
> + /* 32-bit targets; the default */
> + #define INTPTRTYPE long
> + #else
> + /* 16-bit targets; we silently assume sizeof(short)==2 and
> sizeof(long)==4 */
> + #define INTPTRTYPE short
> + #endif
> +#endif
> +
> /* Nonzero if X is not aligned on a "long" boundary.
> * This macro is used to skip a few bytes to find an aligned pointer.
> * It's better to keep it as is even if _HAVE_HW_MISALIGNED_ACCESS is
> enabled,
> * to avoid small performance penalties (if they are not zero). */
> -#define UNALIGNED_X(X) ((long)(X) & (sizeof (long) - 1))
> +#define UNALIGNED_X(X) ((long)(INTPTRTYPE)(X) & (sizeof (long) - 1))
>
> #ifdef _HAVE_HW_MISALIGNED_ACCESS
> /* Hardware performs unaligned operations with little
> @@ -30,7 +44,8 @@ int __wcwidth (wint_t);
> #else /* _HAVE_HW_MISALIGNED_ACCESS */
> /* Nonzero if either X or Y is not aligned on a "long" boundary. */
> #define UNALIGNED_X_Y(X, Y) \
> - (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
> + (((long)(INTPTRTYPE)X & (sizeof (long) - 1)) | \
> + ((long)(INTPTRTYPE)Y & (sizeof (long) - 1)))
> #endif /* _HAVE_HW_MISALIGNED_ACCESS */
>
> /* How many bytes are copied each iteration of the word copy loop. */
> --
> 2.54.0
>
>
@@ -1,5 +1,6 @@
#include <_ansi.h>
#include <../ctype/local.h>
+#include <stdint.h>
/* internal function to compute width of wide char. */
int __wcwidth (wint_t);
@@ -17,11 +18,24 @@ int __wcwidth (wint_t);
# define __inhibit_loop_to_libcall
#endif
+#ifdef __INTPTR_TYPE__
+ #define INTPTRTYPE intptr_t
+#else
+ /* Fallback, just in case there is no intptr_t on a target... */
+ #if __SIZEOF_POINTER__ > __SIZEOF_SHORT__
+ /* 32-bit targets; the default */
+ #define INTPTRTYPE long
+ #else
+ /* 16-bit targets; we silently assume sizeof(short)==2 and sizeof(long)==4 */
+ #define INTPTRTYPE short
+ #endif
+#endif
+
/* Nonzero if X is not aligned on a "long" boundary.
* This macro is used to skip a few bytes to find an aligned pointer.
* It's better to keep it as is even if _HAVE_HW_MISALIGNED_ACCESS is enabled,
* to avoid small performance penalties (if they are not zero). */
-#define UNALIGNED_X(X) ((long)(X) & (sizeof (long) - 1))
+#define UNALIGNED_X(X) ((long)(INTPTRTYPE)(X) & (sizeof (long) - 1))
#ifdef _HAVE_HW_MISALIGNED_ACCESS
/* Hardware performs unaligned operations with little
@@ -30,7 +44,8 @@ int __wcwidth (wint_t);
#else /* _HAVE_HW_MISALIGNED_ACCESS */
/* Nonzero if either X or Y is not aligned on a "long" boundary. */
#define UNALIGNED_X_Y(X, Y) \
- (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
+ (((long)(INTPTRTYPE)X & (sizeof (long) - 1)) | \
+ ((long)(INTPTRTYPE)Y & (sizeof (long) - 1)))
#endif /* _HAVE_HW_MISALIGNED_ACCESS */
/* How many bytes are copied each iteration of the word copy loop. */