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[PATCH 08/14] FreeBSD update of _Alignas, etc.

This adds support for C11.

2013-04-17  Sebastian Huber <>

	* libc/include/sys/cdefs.h (_Alignas): New define.
	(_Alignof): Likewise.
	(__generic): Likewise.
	(_Noreturn): Likewise.
	(_Static_assert): Likewise.
	(_Thread_local): Likewise.
 newlib/libc/include/sys/cdefs.h |   45 +++++++++++++++++++++++++++++++++++++++
 1 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/newlib/libc/include/sys/cdefs.h b/newlib/libc/include/sys/cdefs.h
index d8c32cc..6f2e8c9 100644
--- a/newlib/libc/include/sys/cdefs.h
+++ b/newlib/libc/include/sys/cdefs.h
@@ -261,6 +261,51 @@
+ * Keywords added in C11.
+ */
+#if defined(__cplusplus) && __cplusplus >= 201103L
+#define	_Alignas(e)		alignas(e)
+#define	_Alignof(e)		alignof(e)
+#define	_Noreturn		[[noreturn]]
+#define	_Static_assert(e, s)	static_assert(e, s)
+/* FIXME: change this to thread_local when clang in base supports it */
+#define	_Thread_local		__thread
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
+/* Do nothing.  They are language keywords. */
+/* Not supported.  Implement them using our versions. */
+#define	_Alignas(x)		__aligned(x)
+#define	_Alignof(x)		__alignof(x)
+#define	_Noreturn		__dead2
+#define	_Thread_local		__thread
+#ifdef __COUNTER__
+#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]
+#define	_Static_assert(x, y)	struct __hack
+ * Emulation of C11 _Generic().  Unlike the previously defined C11
+ * keywords, it is not possible to implement this using exactly the same
+ * syntax.  Therefore implement something similar under the name
+ * __generic().  Unlike _Generic(), this macro can only distinguish
+ * between a single type, so it requires nested invocations to
+ * distinguish multiple cases.
+ */
+#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
+#define	__generic(expr, t, yes, no)					\
+	_Generic(expr, t: yes, default: no)
+#elif __GNUC_PREREQ__(3, 1) && !defined(__cplusplus)
+#define	__generic(expr, t, yes, no)					\
+	__builtin_choose_expr(						\
+	    __builtin_types_compatible_p(__typeof(expr), t), yes, no)
  * Given the pointer x to the member m of the struct s, return
  * a pointer to the containing structure.  When using GCC, we first
  * assign pointer x to a local variable, to check that its type is

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