In message: <[EMAIL PROTECTED]>
Carlo Marcelo Arenas Belon <[EMAIL PROTECTED]> writes:
: On Sun, Nov 11, 2007 at 10:06:34AM -0600, Carlo Marcelo Arenas Belon wrote:
: > On Sun, Nov 11, 2007 at 09:30:26AM -0500, Ben Taylor wrote:
: > > So the macro turns the last _INTC_ARRAY(NULL) into
: > >
: > > "NULL, sizeof(NULL)/sizeof(*NULL)
: >
: > in my 64bit linux using gcc-4.1.2 it becomes instead :
: >
: > ((void *)0), sizeof(((void *)0))/sizeof(*((void *)0))
: >
: > what version of gcc (gcc -v) are you using in that Solaris 10 box? (HINT:
not
: > all available versions of gcc compile qemu correctly) :
: >
: > http://www.opensolaris.org/os/project/qemu/host/gcc-failures/
:
: That didn't sound as clear as it should, so I booted an OpenSolaris Nevada 70b
: using the sun provided gcc :
:
: $ uname -a
: SunOS dell 5.11 snv_70b i86pc i386 i86pc
: $ gcc -v
: Reading specs from /usr/sfw/lib/gcc/i386-pc-solaris2.11/3.4.3/specs
: Configured with: /builds2/sfwnv-gate/usr/src/cmd/gcc/gcc-3.4.3/configure
: --prefix=/usr/sfw --with-as=/usr/sfw/bin/gas --with-gnu-as
: --with-ld=/usr/ccs/bin/ld --without-gnu-ld --enable-languages=c,c++,f77,objc
: --enable-shared
: Thread model: posix
: gcc version 3.4.3 (csl-sol210-3_4-20050802)
:
: and run a test, the problem is in /usr/include/iso/stdio_iso.h that defined
: NULL as an int and not a pointer as shown by :
:
: fndef NULL
: #if defined(_LP64)
: #define NULL 0L
: #else
: #define NULL 0
: #endif
: #endif
:
: contradicting (at least in spirit) the C99 (ISO/IEC 9899:TCS) standard that
: says :
:
: "A pointer to void shall have the same representation and alignment
: requirements as a pointer to a character type"
NULL isn't a pointer. It is a integral constant, per section
6.3.2.3.3 of C99. So *NULL is undefined. If you want a constant
thats an actual pointer, you need to define one special.
6.3.2.3 Pointers
...
[#3] An integer constant expression with the value 0, or
such an expression cast to type void *, is called a null
pointer constant. If a null pointer constant is assigned
to or compared for equality to a pointer, the constant is
converted to a pointer of that type. Such a pointer, called
a null pointer, is guaranteed to compare unequal to a
pointer to any object or function.
[#4] Conversion of a null pointer to another pointer type
yields a null pointer of that type. Any two null pointers
shall compare equal.
7.17 Common definitions <stddef.h>
...
[#3] The macros are
NULL
which expands to an implementation-defined null pointer
constant; and
..
The root cause is of this whole problem is *NULL, an undefined,
unportable construct. That's what should be fixed, not the definition
of NULL if you want this code to be portable.
Warner
