GCJ/minGW produced executables and linux/wine

[Andrew Haley]

Ranjit Mathew writes:
 > >  > Well honestly, I don't know and I'm surprised that it works
 > >  > on Linux (so signal delivery must be the "last mile" in that
 > >  > the OS doesn't really care if the handler returns or not).
 > >
 > > The ANS C standard says that signal handlers may return by doing a
 > > longjmp.  But that's what I meant whan I said this is not a signal
 > > handler and may have other restrictions.  And it seems like it does
 > > indeed have some restrictions.
 > 
 > I found a GCJ document relevant to this discussion at:
 > 
 >     http://gcc.gnu.org/java/port-signals.html
 > 
 > (I had seen it before, but hadn't understood its signficance till now. ;-))

Aw, that's well out of date.  I'd forgotten all about it.  Thanks for
pointing it out to me.  I need to rewrite it.

 > >  > I can imagine that there would be problems on Win32 because
 > >  > this handler is supposed to return a value to the OS telling
 > >  > it whether to execute the default handler (abort program)
 > >  > or whether the exception has been handled successfully.
 > 
 > My conjecture seems correct as this simple program hangs on Win32
 > after printing "Strike 1!", instead of printing "Strike 2!" as well:
 > ------------------------------- 8< --------------------------------
 > public class Snafu {
 >   public static void main( String[] args) {
 >     Object p = null;
 >     try {
 >       System.out.println( p.toString( ));
 >     } catch( NullPointerException e) {
 >       System.err.println( "Strike 1!");
 >     }
 > 
 >     try {
 >       System.out.println( p.toString( ));
 >     } catch( NullPointerException e) {
 >       System.err.println( "Strike 2!");
 >     }
 >   }
 > }
 > ------------------------------- 8< --------------------------------
 > 
 > I guess instead of blindly throwing NullPointerException from within
 > win32_exception_handler( ) in win32.cc, we will have to modify
 > the return address a la MAKE_THROW_FRAME in posix.cc, and return
 > EXCEPTION_CONTINUE_EXECUTION as explicitly allowed by Windows:
 > 
 > http://msdn.microsoft.com/library/en-us/debug/base/setunhandledexceptionfilter.asp

That's a but hairy, but it might work.

-fcheck-references is better in the meantime.

Andrew.