Re: [Qemu-devel] error compiling hw/sh7750.c

[Carlo Marcelo Arenas Belon <carenas@sajinet.com.pe>]

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"

and therefore makes sizeof(*NULL) == 1 solving the problem to compile as it is
done if applying the following patch :

Carlo

---
--- qemu/hw/sh7750.c	Sun Oct  7 09:31:11 2007
+++ qemu/hw/sh7750.c	Sun Nov 11 16:13:13 2007
@@ -29,6 +29,9 @@
 #include "sh7750_regnames.h"
 #include "sh_intc.h"
 
+#undef NULL
+#define NULL ((void *)0)
+
 #define NB_DEVICES 4
 
 typedef struct SH7750State {