On 06/19/15 12:23, Bruce Evans wrote:
On Fri, 19 Jun 2015, Dimitry Andric wrote:
On 19 Jun 2015, at 17:02, Pedro Giffuni <p...@freebsd.org> wrote:
On 19/06/2015 05:16 a.m., David Chisnall wrote:
I only just caught this (having seen the fallout from NetBSD doing
the same thing in a shipping release and the pain that it’s caused):
__weak is a reserved keyword in Objective-C, please pick another
name for this. This in cdefs.h makes it impossible to include any
FreeBSD standard headers in Objective-C programs (of which we have
a couple of hundred in ports) if they use any of the modern
Objective-C language modes.
...
Closely related to this, we are redefining _Noreturn, which is a
reserved keyword in C11.
No, sys/cdefs.h has:
254 /*
255 * Keywords added in C11.
256 */
257
258 #if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 201112L
|| defined(lint)
[...]
284 #if defined(__cplusplus) && __cplusplus >= 201103L
285 #define _Noreturn [[noreturn]]
286 #else
287 #define _Noreturn __dead2
288 #endif
[...]
320 #endif /* __STDC_VERSION__ || __STDC_VERSION__ < 201112L */
So the whole block redefining all the _Xxx identifiers is skipped for
C11 and higher.
I probably pointed this out incorrectly to Pedro.
All uses of _Noreturn are still broken, and also ugly. __dead2 is the
gcc-2 compatible version of the gcc-1 compatible macro __dead. It is
syntactically different from __dead and _Noreturn. It must be placed
after the function parameter list instead of in the function type
declarator because old versions of gcc only accept attributes there.
__dead and presumably _Noreturn must be placed in the function type
declarator. This is incompatible, and also uglier.
I was thinking that _Noreturn can be fixed for older compilers
less disruptively.
I haven't tested the attached patch the idea is to resurrect
__dead and use it for _Noreturn.
Correct version with ugly declarations:
__dead void
foo(void) __dead2;
With the patch we would use:
__Noreturn void
foo(void) _dead2;
Which is still ugly but C11-ish.
Pedro.
Index: sys/sys/cdefs.h
===================================================================
--- sys/sys/cdefs.h (revision 284643)
+++ sys/sys/cdefs.h (working copy)
@@ -207,6 +207,7 @@
* a feature that we cannot live without.
*/
#ifdef lint
+#define __dead
#define __dead2
#define __pure2
#define __unused
@@ -217,11 +218,13 @@
#else
#define __weak __attribute__((__weak__))
#if !__GNUC_PREREQ__(2, 5) && !defined(__INTEL_COMPILER)
+#define __dead __volatile
#define __dead2
#define __pure2
#define __unused
#endif
#if __GNUC__ == 2 && __GNUC_MINOR__ >= 5 && __GNUC_MINOR__ < 7 && !defined(__INTEL_COMPILER)
+#define __dead __attribute__((__noreturn__))
#define __dead2 __attribute__((__noreturn__))
#define __pure2 __attribute__((__const__))
#define __unused
@@ -284,7 +287,7 @@
#if defined(__cplusplus) && __cplusplus >= 201103L
#define _Noreturn [[noreturn]]
#else
-#define _Noreturn __dead2
+#define _Noreturn __dead
#endif
#if !__has_extension(c_static_assert)
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