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Date: Tue, 27 Apr 2010 11:05:16 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject: Re: Cygwin's GCC doesn't like this .sa_handler initialization for    some reason
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On Apr 26 19:54, Dave Korn wrote:
> On 26/04/2010 17:45, Eric Blake wrote:
> > [this was originally raised on the libvirt list]
> > 
> > On 04/25/2010 05:32 AM, Matthias Bolte wrote:
> >> +    struct sigaction action_stop;
> >>  
> >> -    struct sigaction action_stop = {
> >> -        .sa_handler = stop
> >> -    };
> >> +    memset(&action_stop, 0, sizeof action_stop);
> >> +
> >> +    action_stop.sa_handler = stop;
> > 
> > This is because on Linux, sa_handler is a macro that expands into an
> > access of a named member of a named union, whereas on cygwin, sa_handler
> > is a directly named member of an anonymous union.  Is this a gcc bug, or
> > should we be changing cygwin/signal.h to follow Linux' lead of using
> > macros to access named unions to allow source compatibility, since gcc
> > falls flat at performing named initialization of a member of gcc's
> > extension of an anonymous union?
> 
>   This is the long-standing PR10676 :-(
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10676
> 
>   Given the rate of progress so far, I reckon we should adopt Linux'
> workaround.  Hopefully we'll be able to take it back out again someday.

Like this?  We are already using analog definitions in the socket header
files.

Index: include/cygwin/signal.h
===================================================================
RCS file: /cvs/src/src/winsup/cygwin/include/cygwin/signal.h,v
retrieving revision 1.18
diff -u -p -r1.18 signal.h
--- include/cygwin/signal.h	26 Feb 2010 05:43:50 -0000	1.18
+++ include/cygwin/signal.h	27 Apr 2010 07:23:05 -0000
@@ -194,14 +194,16 @@ typedef void (*_sig_func_ptr)(int);
 
 struct sigaction
 {
-  __extension__ union
+  union
   {
     _sig_func_ptr sa_handler;  		/* SIG_DFL, SIG_IGN, or pointer to a function */
     void  (*sa_sigaction) ( int, siginfo_t *, void * );
-  };
+  } __sighandler_or_action;
   sigset_t sa_mask;
   int sa_flags;
 };
+#define sa_handler	__sighandler_or_action.sa_handler
+#define sa_sigaction	__sighandler_or_action.sa_sigaction
 
 #define SA_NOCLDSTOP 1   		/* Do not generate SIGCHLD when children
 					   stop */

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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