[PATCH] Maybe change __size_t definition in <stddef.h>?

[Sebastian Huber]

I work currently on a better FreeBSD compatibility for Newlib.  For
RTEMS we use the network, USB, SD/MMC stacks from FreeBSD.  It would be
nice to use <sys/types.h>, etc. from Newlib directly to compile FreeBSD
user and kernel space files.

Various FreeBSD source and header files need a typedef __size_t via
<sys/_types.h>.  Unfortunately the GCC provided <stddef.h> uses

    #if (defined (__FreeBSD__) && (__FreeBSD__ >= 5)) \
      || defined(__DragonFly__) \
      || defined(__FreeBSD_kernel__)
    /* __size_t is a typedef on FreeBSD 5, must not trash it. */
    #elif defined (__VMS__)
    /* __size_t is also a typedef on VMS.  */
    #else
    #define __size_t
    #endif

and therefore defines __size_t to nothing on Newlib targets which would
trash a __size_t typedef.  There exists no Newlib builtin define which
we could add here.  As a workaround I include <stddef.h> before
<sys/_types.h> in <sys/types.h> and undefine __size_t in <sys/_types.h>.

This works fine so far, but breaks if someone includes <stddef.h> after
<sys/_types.h> the first time.

This patch would address this issue, but I do not know which other
issues it generates.

gcc/ChangeLog
2016-04-15  Sebastian Huber  <sebastian.huber at embedded-brains.de>

	* ginclude/stddef.h (__size_t): Define to __SIZE_TYPE__.
---
 gcc/ginclude/stddef.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/ginclude/stddef.h b/gcc/ginclude/stddef.h
index d711530..8c2e22e 100644
--- a/gcc/ginclude/stddef.h
+++ b/gcc/ginclude/stddef.h
@@ -207,7 +207,7 @@ typedef __PTRDIFF_TYPE__ ptrdiff_t;
 #elif defined (__VMS__)
 /* __size_t is also a typedef on VMS.  */
 #else
-#define __size_t
+#define __size_t __SIZE_TYPE__
 #endif
 #ifndef __SIZE_TYPE__
 #define __SIZE_TYPE__ long unsigned int
-- 
1.8.4.5