[ANNOUNCEMENT] TEST RELEASE: Cygwin 2.4.0-0.11
Eric Blake
eblake@redhat.com
Thu Dec 17 21:16:00 GMT 2015
On 12/17/2015 02:01 PM, Corinna Vinschen wrote:
>> Here's what happens:
>>
>> One of the Gnulib modules includes sys/types.h, which includes sys/select.h
>> because of the recent changes. This brings in Gnulib's sys/select.h, which
>> includes signal.h. We then get the errors I posted because we haven't yet
>> finished including sys/types.h.
Gnulib has been taught to work around early inclusion problems before;
sounds like this will be another case where gnulib has to make sure the
system header is complete before its own replacements kick in.
>>
>> All the build errors disappear if I remove '#include <sys/select.h>' from
>> sys/types.h. You said above that the macros related to select don't really
>> belong in sys/types.h. So why does the latter include sys/select.h?
>
> Because it's done exactly the same way on FreeBSD and OpenBSD:
>
> # if __BSD_VISIBLE
> #include <sys/select.h>
> [...]
>
> Gnulib should allow to work with this to be portable. So why does gnulib
> provide its own sys/select.h? Is it configurable?
I'll raise this on the gnulib list, and we can come up with workarounds.
But bypassing gnulib's sys/select.h probably won't work in general
(gnulib tends to always provide wrapper headers that use #include_next
to the system header, even if nothing is replaced, because it is easier
than trying to figure out when a wrapper header is needed). Of course,
fixing it in gnulib won't help the myriad of projects that will be
bitten by this until they do a new release based on updated gnulib, so
maybe we can also find a way to make cygwin play nice without a gnulib
update required. I'm still investigating.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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