I used n1570 for C11: http://www.iso-9899.info/n1570.html
and n3242 for C++11:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
C11:
stdalign.h:
7.15.1: The header <stdalign.h> defines four macros.
7.15.2: The macro
alignas
expands to _Alignas; the macro
alignof
expands to _Alignof.
7.15.3: The remaining macros are suitable for use in #if preprocessing
directives. They are
__alignas_is_defined
and
__alignof_is_defined
which both expand to the integer constant 1.
stdnoreturn.h:
7.23.1: The header <stdnoreturn.h> defines the macro
noreturn
which expands to _Noreturn.
C++11:
stdalign.h:
18.10.2: The contents of these headers are the same as the Standard C library
headers (...) <stdalign.h> (...) respectively, with the following
changes:
18.10.6: The header <cstdalign> and the header <stdalign.h> shall not define a
macro named alignas.
No mention of stdnoreturn.h.
Note that C++11 does not mention "alignof", even though it mentions
"alignas". Both are defined as keywords (Table 4 - Keywords).
A commit in Clang has this to say:
libstdc++'s <cstdalign> #includes <stdalign.h> and expects it to guard
against
being included in C++. Don't define alignof or alignas in this case. Note
that
the C++11 standard is broken in various ways here (it refers to the contents
of <stdalign.h> in C99, where that header did not exist, and doesn't mention
the alignas macro at all), but we do our best to do what it intended.
So I went ahead and followed Clang, not C++11.
Clang's stdnoreturn.h differs from the standard as well, as it defines
"__noreturn_is_defined". I couldn't find a reason, so I didn't.
stdnoreturn.h isn't mentioned in C++11, so skip the #ifndef __cplusplus.
The commit message in FreeBSD that contains these files notes: "Even
though these header files make little sense to me, they are part of the
standard.". I believe these headers are defined to preserve backwards
compatibility. There might exist code where the keywords "alignas", "alignof",
and "noreturn" are already defined. The standard therefore picked keywords
from the reserved namespace, i.e. ones starting with an underscore
and an upper case letter and provided the headers for convenience.
And also make whitespace in stdbool.h consistent with other files.
Index: include/Makefile
===================================================================
RCS file: /cvs/src/include/Makefile,v
retrieving revision 1.208
diff -u -p -r1.208 Makefile
--- include/Makefile 18 Nov 2015 16:48:34 -0000 1.208
+++ include/Makefile 30 Dec 2015 16:43:53 -0000
@@ -17,8 +17,8 @@ FILES= a.out.h ar.h asr.h assert.h bitst
md5.h memory.h ndbm.h netdb.h netgroup.h nlist.h nl_types.h \
paths.h poll.h pwd.h ranlib.h readpassphrase.h regex.h \
resolv.h rmd160.h search.h setjmp.h sha1.h sha2.h signal.h siphash.h \
- sndio.h \
- spawn.h stdbool.h stddef.h stdio.h stdlib.h string.h strings.h struct.h
\
+ sndio.h spawn.h stdalign.h stdbool.h stddef.h stdio.h stdlib.h \
+ stdnoreturn.h string.h strings.h struct.h \
sysexits.h tar.h tgmath.h time.h ttyent.h unistd.h utime.h \
utmp.h uuid.h vis.h wchar.h wctype.h
Index: include/stdalign.h
===================================================================
RCS file: include/stdalign.h
diff -N include/stdalign.h
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ include/stdalign.h 30 Dec 2015 16:43:53 -0000
@@ -0,0 +1,18 @@
+/* $OpenBSD$ */
+
+/*
+ * Public domain.
+ */
+
+#ifndef _STDALIGN_H_
+#define _STDALIGN_H_
+
+#ifndef __cplusplus
+#define alignas _Alignas
+#define alignof _Alignof
+#endif
+
+#define __alignas_is_defined 1
+#define __alignof_is_defined 1
+
+#endif /* _STDALIGN_H_ */
Index: include/stdbool.h
===================================================================
RCS file: /cvs/src/include/stdbool.h,v
retrieving revision 1.7
diff -u -p -r1.7 stdbool.h
--- include/stdbool.h 4 Sep 2015 23:47:09 -0000 1.7
+++ include/stdbool.h 30 Dec 2015 16:43:53 -0000
@@ -1,4 +1,4 @@
-/* $OpenBSD: stdbool.h,v 1.7 2015/09/04 23:47:09 daniel Exp $ */
+/* $OpenBSD: stdbool.h,v 1.7 2015/09/04 23:47:09 daniel Exp $ */
/*
* Written by Marc Espie, September 25, 1999
Index: include/stdnoreturn.h
===================================================================
RCS file: include/stdnoreturn.h
diff -N include/stdnoreturn.h
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ include/stdnoreturn.h 30 Dec 2015 16:43:53 -0000
@@ -0,0 +1,12 @@
+/* $OpenBSD$ */
+
+/*
+ * Public domain.
+ */
+
+#ifndef _STDNORETURN_H_
+#define _STDNORETURN_H_
+
+#define noreturn _Noreturn
+
+#endif /* _STDNORETURN_H_ */
--
Michal Mazurek
