Re: Problem with: Re: [PATCH] Allow usage of union wait for wait() functions and macros

[Christian Franke <Christian dot Franke at t-online dot de>]

Christopher Faylor wrote:
> On Thu, Dec 08, 2011 at 12:17:11AM +0100, Christian Franke wrote:
> > Christopher Faylor wrote:
> > > ...
> > > /usr/local/src/trunk/objdir.withada/./prev-gcc/g++
> > > -B/usr/local/src/trunk/objdir.withada/./prev-gcc/
> > > ...
> > > -I/usr/local/src/trunk/gcc/gcc/../libdecnumber/bid -I../libdecnumber
> > >     /usr/local/src/trunk/gcc/gcc/ada/adaint.c -o ada/adaint.o
> > > In file included from /usr/local/src/trunk/gcc/gcc/system.h:346:0,
> > >                    from /usr/local/src/trunk/gcc/gcc/ada/adaint.c:107:
> > > /usr/include/sys/wait.h: In function 'int __wait_status_to_int(const wait&)':
> > > /usr/include/sys/wait.h:77:61: error: declaration of C function 'int
> > > __wait_status_to_int(const wait&)' conflicts with
> > > /usr/include/sys/wait.h:75:12: error: previous declaration 'int
> > > __wait_status_to_int(int)' here
> > This suggests that sys/wait.h is included within an extern "C" { ... }
> > block.
> > If this is the case then an extern "C++" {...} block around the C++
> > inline functions of sys/wait.h should fix this.
> > See:
> > http://cygwin.com/ml/cygwin-patches/2011-q4/msg00005.html
> Yes, I'm responding to this very thread.
>
> But, I don't see how extern "c++" fixes anything.  #ifdef __cplusplus maybe...

No, #ifdef __cplusplus won't help. Example:

foo.h:
extern "C" {
#include <sys/wait.h>
}


sys/wait.h:
...
#ifdef __cplusplus
...
inline int __wait_status_to_int(int __status) { .... }
// This fails because both are interpreted as C-functions:
inline int __wait_status_to_int(const union wait &__status) { .... }
...
#endif


Fix:
#ifdef __cplusplus
+extern "C++" {
...
inline int __wait_status_to_int(int __status) { .... }
inline int __wait_status_to_int(const union wait &__status) { .... }
...
+}
#endif


Christian