On Fri, 6 May 2016 10:33:32 -0400 in
<CACLX4jRYhcZ4XZCDKGODYd1PPBcqCcfGUU2aVU=VJskipxiLUg@mail.gmail.com>,
Yaron Minsky <yminsky@janestreet.com> wrote:

> Looping in the Core mailing list, since this seems like a
> core-specific issue.

> > I already have a convenient script to setup cygwin with all modules
> > and to compile opam and it works fine. Just when compiling core,
> > there are two Unix features not implemented in cygwin. One is
> > O_ASYNC. It is easy to patch it away and also easy to make this
> > system dependent in the C file (unix_stubs.c), but I wonder how I
> > could handle this in a portable way in the OCaml wrapper. It looks
> > like this:
> >

Most people that need to make portable code handle flag dependencies on
open() - or other flags on standard functions - in the buildsystem
with a little piece of C code that open() a file created by the
buildsystem with different flags and catch the return code : 

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
...
int retasync = open(/path/to/test/file, O_ASYNC);
...
 
then define a boolean inside the buildsystem to make conditional
compilation based on the boolean. 

Cheers. 

-- 
Jérôme Benoit aka fraggle
Piment Noir - http://piment-noir.org
OpenPGP Key ID : 9FE9161D
Key fingerprint : 9CA4 0249 AF57 A35B 34B3 AC15 FAA0 CB50 9FE9 161D