Re: Version 1.8.1 does not compile on Cygwin 1.7.14

From: Eric Blake <eblake@redhat.com>
Date: Jan 26, 2013, 00:34 UTC
Message-ID: <51032481.4030707@redhat.com>
In-Reply-To: <7v38xo3irh.fsf@alter.siamese.dyndns.org>

On 01/25/2013 05:11 PM, Junio C Hamano wrote:

Show 18 quoted lines

> Mark Levedahl <mlevedahl@gmail.com> writes:
> 
>> Cygwin and Windows should be treated as completely separate platforms:
>> if __CYGWIN__ is defined, do one thing, if not, go ahead and check
>> WIN32, but the WIN32 macro should never be tested once we know the
>> platform is CYGWIN - these really are different platforms (if you are
>> unsure of this, consider that Cygwin includes a cross-compiler to
>> target native Win32 as the Cygwin maintainers recognized the platforms
>> are different).
> 
> Not disagreeing with your conclusion (they should be treated as
> different), why does it define WIN32 in the first place?
> 
> Perhaps we would want
> 
> 	#ifdef __CYGWIN__
>         #undef WIN32
>         #endif

Wouldn't work. Cygwin gcc does NOT define WIN32; rather, the inclusion of a Windows system header (generally discouraged, but sometimes a necessary evil) might cause WIN32 to be defined for all subsequent headers.

Which is why other projects, like gnulib, have

# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__

all over the place.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org