Re: [PATCH] Silence -Wpointer-to-int-cast warnings in newlib/libc/string/local.h.

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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=E2=80=AFPM Jan Dubiec <[email protected]> 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: cas=
t
> 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 <[email protected]>
> ---
>  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)=3D=3D2 and
> sizeof(long)=3D=3D4 */
> +       #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
>
>

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<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family:verdana,=
sans-serif">Hi Jan,</div><div class=3D"gmail_default" style=3D"font-family:=
verdana,sans-serif"><br></div><div class=3D"gmail_default" style=3D"font-fa=
mily:verdana,sans-serif">The fallback for intptr_t is unnecessary.=C2=A0 Ac=
cording to libc/include/sys/_intsup.h, gcc 3.2 or higher should support</di=
v><div class=3D"gmail_default" style=3D"font-family:verdana,sans-serif">the=
 intptr info we need plus there is an #error statement if it isn&#39;t.=C2=
=A0 So, the code should just use intptr_t.=C2=A0=C2=A0</div><div class=3D"g=
mail_default" style=3D"font-family:verdana,sans-serif"><br></div><div class=
=3D"gmail_default" style=3D"font-family:verdana,sans-serif">-- Jeff J.</div=
></div><br><div class=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr=
" class=3D"gmail_attr">On Thu, Jul 16, 2026 at 7:40=E2=80=AFPM Jan Dubiec &=
lt;<a href=3D"mailto:[email protected]">[email protected]</a>&gt; wrote:<br></div><blockquo=
te class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px =
solid rgb(204,204,204);padding-left:1ex">Compiling the library for a 16-bit=
 target results in numerous warnings<br>
(some of which are shown below) in the mem*, str*, and several other<br>
functions. The existing code incorrectly assumes that pointers are 32<br>
bits wide. This patch removes that assumption and fixes the resulting<br>
warnings.<br>
<br>
[...]<br>
=C2=A0 CC=C2=A0 =C2=A0 =C2=A0 =C2=A0libc/string/libc_a-memchr.o<br>
In file included from ../../../../../../../newlib/newlib/libc/string/memchr=
.c:35:<br>
../../../../../../../newlib/newlib/libc/string/memchr.c: In function &#39;m=
emchr&#39;:<br>
../../../../../../../newlib/newlib/libc/string/local.h:24:25: warning: cast=
 from pointer to integer of different size [-Wpointer-to-int-cast]<br>
=C2=A0 =C2=A024 | #define UNALIGNED_X(X) ((long)(X) &amp; (sizeof (long) - =
1))<br>
=C2=A0 =C2=A0 =C2=A0 |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0^<br>
../../../../../../../newlib/newlib/libc/string/memchr.c:50:10: note: in exp=
ansion of macro &#39;UNALIGNED_X&#39;<br>
=C2=A0 =C2=A050 |=C2=A0 =C2=A0while (UNALIGNED_X(src))<br>
=C2=A0 =C2=A0 =C2=A0 |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 ^~~~~~~~~~~<br>
=C2=A0 CC=C2=A0 =C2=A0 =C2=A0 =C2=A0libc/string/libc_a-memcmp.o<br>
In file included from ../../../../../../../newlib/newlib/libc/string/memcmp=
.c:33:<br>
../../../../../../../newlib/newlib/libc/string/memcmp.c: In function &#39;m=
emcmp&#39;:<br>
../../../../../../../newlib/newlib/libc/string/local.h:33:5: warning: cast =
from pointer to integer of different size [-Wpointer-to-int-cast]<br>
=C2=A0 =C2=A033 |=C2=A0 =C2=A0(((long)X &amp; (sizeof (long) - 1)) | ((long=
)Y &amp; (sizeof (long) - 1)))<br>
=C2=A0 =C2=A0 =C2=A0 |=C2=A0 =C2=A0 =C2=A0^<br>
../../../../../../../newlib/newlib/libc/string/memcmp.c:63:38: note: in exp=
ansion of macro &#39;UNALIGNED_X_Y&#39;<br>
=C2=A0 =C2=A063 |=C2=A0 =C2=A0if (!TOO_SMALL_LITTLE_BLOCK(n) &amp;&amp; !UN=
ALIGNED_X_Y(s1,s2))<br>
=C2=A0 =C2=A0 =C2=A0 |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 ^~~~~~~~~~~~~<br>
../../../../../../../newlib/newlib/libc/string/local.h:33:39: warning: cast=
 from pointer to integer of different size [-Wpointer-to-int-cast]<br>
=C2=A0 =C2=A033 |=C2=A0 =C2=A0(((long)X &amp; (sizeof (long) - 1)) | ((long=
)Y &amp; (sizeof (long) - 1)))<br>
=C2=A0 =C2=A0 =C2=A0 |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0^<br>
../../../../../../../newlib/newlib/libc/string/memcmp.c:63:38: note: in exp=
ansion of macro &#39;UNALIGNED_X_Y&#39;<br>
=C2=A0 =C2=A063 |=C2=A0 =C2=A0if (!TOO_SMALL_LITTLE_BLOCK(n) &amp;&amp; !UN=
ALIGNED_X_Y(s1,s2))<br>
=C2=A0 =C2=A0 =C2=A0 |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 ^~~~~~~~~~~~~<br>
[...]<br>
<br>
Signed-off-by: Jan Dubiec &lt;<a href=3D"mailto:[email protected]" target=3D"_blank=
">[email protected]</a>&gt;<br>
---<br>
=C2=A0newlib/libc/string/local.h | 19 +++++++++++++++++--<br>
=C2=A01 file changed, 17 insertions(+), 2 deletions(-)<br>
<br>
diff --git a/newlib/libc/string/local.h b/newlib/libc/string/local.h<br>
index 012a30d16..79436ab69 100644<br>
--- a/newlib/libc/string/local.h<br>
+++ b/newlib/libc/string/local.h<br>
@@ -1,5 +1,6 @@<br>
=C2=A0#include &lt;_ansi.h&gt;<br>
=C2=A0#include &lt;../ctype/local.h&gt;<br>
+#include &lt;stdint.h&gt;<br>
<br>
=C2=A0/* internal function to compute width of wide char. */<br>
=C2=A0int __wcwidth (wint_t);<br>
@@ -17,11 +18,24 @@ int __wcwidth (wint_t);<br>
=C2=A0# define __inhibit_loop_to_libcall<br>
=C2=A0#endif<br>
<br>
+#ifdef __INTPTR_TYPE__<br>
+=C2=A0 #define INTPTRTYPE intptr_t<br>
+#else<br>
+=C2=A0 /* Fallback, just in case there is no intptr_t on a target... */<br=
>
+=C2=A0 #if __SIZEOF_POINTER__ &gt; __SIZEOF_SHORT__<br>
+=C2=A0 =C2=A0 /* 32-bit targets; the default */<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0#define INTPTRTYPE long<br>
+=C2=A0 #else<br>
+=C2=A0 =C2=A0 /* 16-bit targets; we silently assume sizeof(short)=3D=3D2 a=
nd sizeof(long)=3D=3D4 */<br>
+=C2=A0 =C2=A0 =C2=A0 =C2=A0#define INTPTRTYPE short<br>
+=C2=A0 #endif<br>
+#endif<br>
+<br>
=C2=A0/* Nonzero if X is not aligned on a &quot;long&quot; boundary.<br>
=C2=A0 * This macro is used to skip a few bytes to find an aligned pointer.=
<br>
=C2=A0 * It&#39;s better to keep it as is even if _HAVE_HW_MISALIGNED_ACCES=
S is enabled,<br>
=C2=A0 * to avoid small performance penalties (if they are not zero).=C2=A0=
 */<br>
-#define UNALIGNED_X(X) ((long)(X) &amp; (sizeof (long) - 1))<br>
+#define UNALIGNED_X(X) ((long)(INTPTRTYPE)(X) &amp; (sizeof (long) - 1))<b=
r>
<br>
=C2=A0#ifdef _HAVE_HW_MISALIGNED_ACCESS<br>
=C2=A0/* Hardware performs unaligned operations with little<br>
@@ -30,7 +44,8 @@ int __wcwidth (wint_t);<br>
=C2=A0#else /* _HAVE_HW_MISALIGNED_ACCESS */<br>
=C2=A0/* Nonzero if either X or Y is not aligned on a &quot;long&quot; boun=
dary.=C2=A0 */<br>
=C2=A0#define UNALIGNED_X_Y(X, Y) \<br>
-=C2=A0 (((long)X &amp; (sizeof (long) - 1)) | ((long)Y &amp; (sizeof (long=
) - 1)))<br>
+=C2=A0 (((long)(INTPTRTYPE)X &amp; (sizeof (long) - 1)) | \<br>
+=C2=A0 =C2=A0((long)(INTPTRTYPE)Y &amp; (sizeof (long) - 1)))<br>
=C2=A0#endif /* _HAVE_HW_MISALIGNED_ACCESS */<br>
<br>
=C2=A0/* How many bytes are copied each iteration of the word copy loop.=C2=
=A0 */<br>
-- <br>
2.54.0<br>
<br>
</blockquote></div>

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