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. Fam
