Process a lot of feedback from bde@ on <sys/cdefs.h>:

- Add __alignof() for non-GCC and GCC < 2.95.
- Simply implement the C1X keywords on top of the existing __macros.
- Add struct __hack to _Static_assert to require consumers to add a
  semicolon.
- Add an extra underscore to __assert_ to allow it to be combined with
  locally defined versions of CTASSERT in the tree.
- Add proper casts to __offsetof() to make it work for cases where
  sizeof(size_t) != sizeof(uintptr_t).
- Globally replace size_t and uintptr_t by __size_t and __uintptr_t.
  This removes the dependency on <sys/types.h> / <stdint.h>. Practically
  any header file ends up including <machines/_types.h> somehow.
- Change argument names of macros to match with the rest of the file.

MFC after:	3 months

1 files changed, 18 insertions, 20 deletions

diff --git a/sys/sys/cdefs.h b/sys/sys/cdefs.h
index 784d7f0..1a87a5d 100644
--- a/sys/sys/cdefs.h
+++ b/sys/sys/cdefs.h
@@ -218,6 +218,10 @@
 #endif
 #endif
 
+#if !__GNUC_PREREQ__(2, 95)
+#define	__alignof(x)	__offsetof(struct { char __a; x __b; }, __b)
+#endif
+
 /*
  * Keywords added in C1X.
  */
@@ -230,24 +234,17 @@
 #elif defined(__STDC_VERSION__) && __STDC_VERSION__ > 201000L
 /* Do nothing.  They are language keywords. */
 #else
-/* Not supported.  Implement them manually. */
-#ifdef __GNUC__
-#define	_Alignas(e)		__attribute__((__aligned__(e)))
-#define	_Alignof(e)		__alignof__(e)
-#define	_Noreturn		__attribute__((__noreturn__))
+/* Not supported.  Implement them using our versions. */
+#define	_Alignas(x)		__aligned(x)
+#define	_Alignof(x)		__alignof(x)
+#define	_Noreturn		__dead2
 #define	_Thread_local		__thread
-#else
-#define	_Alignas(e)
-#define	_Alignof(e)		__offsetof(struct { char __a; e __b; }, __b)
-#define	_Noreturn
-#define	_Thread_local
-#endif
 #ifdef __COUNTER__
-#define	_Static_assert(e, s)	__Static_assert(e, __COUNTER__)
-#define	__Static_assert(e, c)	___Static_assert(e, c)
-#define	___Static_assert(e, c)	typedef char __assert ## c[(e) ? 1 : -1]
+#define	_Static_assert(x, y)	__Static_assert(x, __COUNTER__)
+#define	__Static_assert(x, y)	___Static_assert(x, y)
+#define	___Static_assert(x, y)	typedef char __assert_ ## y[(x) ? 1 : -1]
 #else
-#define	_Static_assert(e, s)
+#define	_Static_assert(x, y)	struct __hack
 #endif
 #endif
 
@@ -363,10 +360,11 @@
 #define __offsetof(type, field)	 __builtin_offsetof(type, field)
 #else
 #ifndef __cplusplus
-#define	__offsetof(type, field)	((size_t)(&((type *)0)->field))
+#define	__offsetof(type, field) \
+	((__size_t)(__uintptr_t)((const volatile void *)&((type *)0)->member))
 #else
 #define __offsetof(type, field)					\
-  (__offsetof__ (reinterpret_cast <size_t>			\
+  (__offsetof__ (reinterpret_cast <__size_t>			\
                  (&reinterpret_cast <const volatile char &>	\
                   (static_cast<type *> (0)->field))))
 #endif
@@ -495,15 +493,15 @@
 #endif
 
 #ifndef	__DECONST
-#define	__DECONST(type, var)	((type)(uintptr_t)(const void *)(var))
+#define	__DECONST(type, var)	((type)(__uintptr_t)(const void *)(var))
 #endif
 
 #ifndef	__DEVOLATILE
-#define	__DEVOLATILE(type, var)	((type)(uintptr_t)(volatile void *)(var))
+#define	__DEVOLATILE(type, var)	((type)(__uintptr_t)(volatile void *)(var))
 #endif
 
 #ifndef	__DEQUALIFY
-#define	__DEQUALIFY(type, var)	((type)(uintptr_t)(const volatile void *)(var))
+#define	__DEQUALIFY(type, var)	((type)(__uintptr_t)(const volatile void *)(var))
 #endif
 
 /*-