On 07/28/2016 09:29 AM, Halil Pasic wrote: >> You mean va_start, not start_va. And actually, C11 is clear that errno >> is unspecified after library functions (but not macros) that don't >> explicitly state otherwise. Since va_start() is a macro and not a >> library function, that means va_start does NOT have carte blanche >> permission to modify errno. For more reading on the topic: > > I also considered this function/macro thing but in the end I am not > aware of anything in C11 what would prohibit va_start to modify errno -- > correct me if I'm wrong. With that it boils down to 'may' and relying on > 'does not' means you are not covered by the standard C11 (but may > be covered by something else -- in which case this should be documented > in HACKING). > >> >> http://austingroupbugs.net/view.php?id=384 >> > > This got rejected, or? Means that there is no willingness to introduce > this guarantee at POSIX level? >
That particular bug report was rejected because the POSIX folks decided that the C11 wording was clear enough that va_start() was already guaranteed to not mess with errno, so no additionally wording was needed in POSIX. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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