unfortunately this eliminates the ability of the compiler to diagnose
some dangerous/incorrect usage, but POSIX requires (as an extension to
the C language, i.e. CX shaded) that NULL have type void *. plain C
allows it to be defined as any null pointer constant.
the definition 0L is preserved for C++ rather than reverting to plain
0 to avoid dangerous behavior in non-conforming programs which use
NULL as a variadic sentinel. (it's impossible to use (void *)0 for C++
since C++ lacks the proper implicit pointer conversions, and other
popular alternatives like the GCC __null extension seem non-conforming
to the standard's requirements.)
#include <features.h>
+#ifdef __cplusplus
#define NULL 0L
+#else
+#define NULL ((void*)0)
+#endif
#define LC_CTYPE 0
#define LC_NUMERIC 1
#ifndef _STDDEF_H
#define _STDDEF_H
+#ifdef __cplusplus
#define NULL 0L
+#else
+#define NULL ((void*)0)
+#endif
#define __NEED_ptrdiff_t
#define __NEED_size_t
#include <bits/alltypes.h>
+#ifdef __cplusplus
#define NULL 0L
+#else
+#define NULL ((void*)0)
+#endif
#undef EOF
#define EOF (-1)
#include <features.h>
+#ifdef __cplusplus
#define NULL 0L
+#else
+#define NULL ((void*)0)
+#endif
#define __NEED_size_t
#define __NEED_wchar_t
#include <features.h>
+#ifdef __cplusplus
#define NULL 0L
+#else
+#define NULL ((void*)0)
+#endif
#define __NEED_size_t
#if defined(_POSIX_SOURCE) || defined(_POSIX_C_SOURCE) \
#include <features.h>
+#ifdef __cplusplus
#define NULL 0L
+#else
+#define NULL ((void*)0)
+#endif
+
#define __NEED_size_t
#define __NEED_time_t
#define SEEK_CUR 1
#define SEEK_END 2
+#ifdef __cplusplus
#define NULL 0L
+#else
+#define NULL ((void*)0)
+#endif
#define __NEED_size_t
#define __NEED_ssize_t
#define WCHAR_MIN (-1-0x7fffffff+L'\0')
#endif
+#ifdef __cplusplus
#define NULL 0L
+#else
+#define NULL ((void*)0)
+#endif
#undef WEOF
#define WEOF 0xffffffffU