Re: autoconf: AC_SYS_LARGEFILE should output to CPPFLAGS

[Eric Blake]

On 01/25/2017 10:57 AM, Thorsten Glaser wrote:
> On Wed, 25 Jan 2017, Thorsten Glaser wrote:
> 
>> Looking at the source, AC_SYS_LARGEFILE calls AC_DEFINE_UNQUOTED,
>> which appends to DEFS (which I agree with Tom Dickey is wrong) as
>> Florian Weimer said, but — even more confusingly — only when
>> AC_CONFIG_HEADERS is not used.
>>
>> If AC_CONFIG_HEADERS is used, the definition is only written to
>> its output file (config.h by default).
>>
>> This is even more unfortunate, because now, if any program includes
>> a glibc system header before "config.h", the definition will be
>> ignored, because it comes too late.
>>
>> CPPFLAGS is r̲e̲a̲l̲l̲y̲ the correct place for this. Again.
> 
> Let’s keep track of t̲h̲i̲s̲ bug here <address@hidden>.
> Again, please forward this upstream, too.
> 
> The workaround I was forced to use in a real-world package is thus:
> https://anonscm.debian.org/cgit/pkg-remote/xrdp.git/plain/debian/patches/lfs.diff?id=e17430063641d44f5596b5bfc1b32ac4ba39f9f1

If the real-world package is not including config.h first, then that is
a bug in the real-world package that should be fixed there.  Autoconf
clearly documents that if you create config.h, it MUST be included
first, before any system headers.

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

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