I can no longer compile C code linked to the Openwindows/xview-devel
toolkit using gcc in Cygwin 32 bits, installed on Windows 7 32 or 64
bit systems. I run setup-x86 weekly to update Cygwin - compilation ran
fine in August 2015 but by mid September 2015 it was failing on the
same code.

I can reproduce this by compiling C code from the xview-examples
package (from e.g., Debian i386
https://packages.debian.org/jessie/xview-examples ), to eliminate any
issues with my specific code. For example,

$ cd usr/share/doc/xviewg/examples/panels

$ cc -O -I/usr/openwin/include simple_panel.c -L/usr/openwin/lib
-lxview -lolgx -lX11 -o simple_panel

In file included from /usr/openwin/include/xview/pkg.h:27:0,
                 from /usr/openwin/include/xview/pkg_public.h:19,
                 from /usr/openwin/include/xview/generic.h:39,
                 from /usr/openwin/include/xview/xview_xvin.h:41,
                 from /usr/openwin/include/xview/xview.h:18,
                 from simple_panel.c:5:
/usr/openwin/include/xview/notify.h:34:13: error: conflicting types
for ‘ucontext_t’
 typedef int ucontext_t;
             ^
In file included from /usr/include/sys/signal.h:357:0,
                 from /usr/include/signal.h:5,
                 from /usr/openwin/include/xview/xview_xvin.h:18,
                 from /usr/openwin/include/xview/xview.h:18,
                 from simple_panel.c:5:
/usr/include/sys/ucontext.h:24:3: note: previous declaration of
‘ucontext_t’ was here
 } ucontext_t;
   ^

There now appears to be an issue with the definition of ucontext_t in
xview-devel with respect to Cygwin. If I manually edit
/usr/openwin/include/xview/base.h and change line 70 from undef to
#define SYSV_UCONTEXT
... the example above then compiles fine.

I cannot find any reference to recent Cygwin updates related to the
definition of ucontext_t - and I may be fixing a symptom of something
else rather than the underlying cause. Any suggestions?

Thanks

Paul