[xproto] _X_NONNULL and C++ 11

[walter harms]

Am 27.05.2017 11:02, schrieb Matthieu Herrb:
> Hi,
> 
> Marc Espie recently found out that the X_NONNULL macro in Xfuncproto.h
> is generating spurious warnings when included in C++ code build with
> clang++ -std=c++11.
> 
> Other OpenBSD developper tried to find uses of the macro in the wild
> and didn't find any, even in the X.Org lib app or xserver tree.
> 
> So, should this macro definition be removed alltogether (acking that
> no-one cares to use it) or just apply the patch below ?
> 
> From 6ae956660879d70e078025c3d8f1ac3fd438cad2 Mon Sep 17 00:00:00 2001
> From: Marc Espie <espie at nerim.net>
> Date: Sat, 27 May 2017 10:55:04 +0200
> Subject: [PATCH] Fix compiling any C++ code including Xfuncproto.h with
>  clang++ -std=c++11
> 
> It shouldn't warn, bu it will use the "legacy" varargs macros and whine.
> ---
>  Xfuncproto.h.in | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Xfuncproto.h.in b/Xfuncproto.h.in
> index b88493d..1be3f55 100644
> --- a/Xfuncproto.h.in
> +++ b/Xfuncproto.h.in
> @@ -166,7 +166,8 @@ in this Software without prior written authorization from The Open Group.
>     argument macros, must be only used inside #ifdef _X_NONNULL guards, as
>     many legacy X clients are compiled in C89 mode still. */
>  #if __has_attribute(nonnull) \
> -    && defined(__STDC_VERSION__) && (__STDC_VERSION__ - 0 >= 199901L) /* C99 */
> +    && (defined(__STDC_VERSION__) && (__STDC_VERSION__ - 0 >= 199901L) \
> +    || (defined(__cplusplus) && (__cplusplus - 0 >= 201103L))) /* C99 C++11 */
>  #define _X_NONNULL(...)  __attribute__((nonnull(__VA_ARGS__)))
>  #elif __has_attribute(nonnull) \
>      || defined(__GNUC__) &&  ((__GNUC__ * 100 + __GNUC_MINOR__) >= 303)
> 
> 
> 

So far i understand this is a problem with clang++. "spurious warning" sounds for me more
like a compiler bug (assuming that gcc has no problems with that). So why not make that
a NOOP until fixed in clang ?

re,
 wh