On Tue, Nov 15, 2016 at 11:00:16PM +0800, Fam Zheng wrote: > On Tue, 11/15 14:45, Stefan Hajnoczi wrote: > > On Tue, Nov 15, 2016 at 08:44:17PM +0800, Fam Zheng wrote: > > > On Tue, 11/15 10:18, Stefan Hajnoczi wrote: > > > > Fam, Markus: Unfortunately neither the clean-includes script nor its > > > > patch series cover letter explains *why* osdep.h should be included > > > > before system headers. > > > > > > I don't know Peter's exact intention either, but AFAICT it is about the > > > few > > > quirks in osdep.h: > > > > > > > > > /* Older versions of C++ don't get definitions of various macros from > > > * stdlib.h unless we define these macros before first inclusion of > > > * that system header. > > > */ > > > #ifndef __STDC_CONSTANT_MACROS > > > #define __STDC_CONSTANT_MACROS > > > #endif > > > #ifndef __STDC_LIMIT_MACROS > > > #define __STDC_LIMIT_MACROS > > > #endif > > > #ifndef __STDC_FORMAT_MACROS > > > #define __STDC_FORMAT_MACROS > > > #endif > > > > > > /* The following block of code temporarily renames the daemon() function > > > so the > > > * compiler does not see the warning associated with it in stdlib.h on OSX > > > */ > > > #ifdef __APPLE__ > > > #define daemon qemu_fake_daemon_function > > > #include <stdlib.h> > > > #undef daemon > > > extern int daemon(int, int); > > > #endif > > > > > > <...> > > > > > > > > > /* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with > > > * the wrong type. Our replacement isn't usable in preprocessor > > > * expressions, but it is sufficient for our needs. */ > > > #if defined(HAVE_BROKEN_SIZE_MAX) && HAVE_BROKEN_SIZE_MAX > > > #undef SIZE_MAX > > > #define SIZE_MAX ((size_t)-1) > > > #endif > > > > This is exactly the kind of stuff we should not be doing to the libqnio > > header file! > > > > Those redefinitions are useful for QEMU code. They should not be done > > to third-party system headers though. > > But we still want to include osdep.h before libqnio pulls in stdint.h. If we > don't make osdep.h the very first, that cannot be guaranteed.
Thanks, that makes sense! I'll add a comment to clean-includes with this explanation of why osdep.h must go before system headers. Stefan
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