Cygwin build failure following [PATCH 3/3 v5] Demangler crash handler

["Pierre Muller" <pierre.muller@ics-cnrs.unistra.fr>]

   Hi Gary,
I think your patch generates
build failure on cygwin32:

../../../binutils-gdb/gdb/cp-support.c: In function 'gdb_demangle':
../../../binutils-gdb/gdb/cp-support.c:1560:21: erreur: 'SA_ONSTACK'
undeclared (first use in this function)
       sa.sa_flags = SA_ONSTACK;
                     ^
../../../binutils-gdb/gdb/cp-support.c:1560:21: note: each undeclared
identifier is reported only once for each function it appears in
Makefile:1075: recipe for target 'cp-support.o' failed

The reason is that SA_ONSTACK
is not defined in cygwin's /usr/include/signal.h header

whereas SA_RESTART is defined in signal header,
and HAVE_SIGACTION is set in config.h


> +#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
> +      sa.sa_handler = gdb_demangle_signal_handler;
> +      sigemptyset (&sa.sa_mask);
> +      sa.sa_flags = SA_ONSTACK;
> +      sigaction (SIGSEGV, &sa, &old_sa);
> +#else
> +      ofunc = (void (*)()) signal (SIGSEGV,
> gdb_demangle_signal_handler);
> +#endif

A simple patch would probably be to add a separate check
#ifdef SA_ONSTACK
  sa.sa_flags = SA_O?STACK;
#endif

But I honestly don't know enough about
Cygwin signal emulation to know if this is a correct fix or not.

  Maybe Corinna Vinschen can comment on this?

Pierre Muller