C99 requires SIZE_MAX to be declared with the same type as the integral promotion of size_t, but OSX mistakenly defines it as an 'unsigned long long' expression even though size_t is only 'unsigned long'. Rather than futzing around with whether size_t is 32- or 64-bits wide (which would be needed if we cared about using SIZE_T in a #if expression), let the compiler get the right type for us by virtue of integer promotion - if we later need it during the preprocessor, the build will break on Mac until we improve our replacement.
See also https://patchwork.ozlabs.org/patch/542327/ for an instance where the wrong type trips us up if we don't fix it for good in osdep.h. Some versions of glibc make a similar mistake with SSIZE_MAX; the goal is that the approach of this patch could be copied to work around that problem if it ever becomes important to us. Signed-off-by: Eric Blake <ebl...@redhat.com> --- v1 was here: https://lists.gnu.org/archive/html/qemu-devel/2016-07/msg02520.html The topic recently came up again, and I noticed this patch sitting on one of my older branches, so I've taken another shot at it. https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg00950.html v2: rewrite into a configure check (not sure if directly adding a -D to QEMU_CFLAGS is the best, so advice welcome) v3: Use config-host.mak rather than direct -D I lack easy access to a Mac box, so again this needs testing... --- include/qemu/osdep.h | 8 ++++++++ configure | 16 ++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 9e9fa61..2520e63 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -141,6 +141,14 @@ extern int daemon(int, int); # error Unknown pointer size #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 HAVE_BROKEN_SIZE_MAX +#undef SIZE_MAX +#define SIZE_MAX ((sizeof(char)) * -1) +#endif + #ifndef MIN #define MIN(a, b) (((a) < (b)) ? (a) : (b)) #endif diff --git a/configure b/configure index 5751d8e..dd9e679 100755 --- a/configure +++ b/configure @@ -1725,6 +1725,19 @@ if test "$cocoa" = "yes"; then sdl=no fi +# Some versions of Mac OS X incorrectly define SIZE_MAX +cat > $TMPC << EOF +#include <stdint.h> +#include <stdio.h> +int main(int argc, char *argv[]) { + return printf("%zu", SIZE_MAX); +} +EOF +have_broken_size_max=no +if ! compile_object -Werror ; then + have_broken_size_max=yes +fi + ########################################## # L2TPV3 probe @@ -5245,6 +5258,9 @@ fi if test "$have_ifaddrs_h" = "yes" ; then echo "HAVE_IFADDRS_H=y" >> $config_host_mak fi +if test "$have_broken_size_max" = "yes" ; then + echo "HAVE_BROKEN_SIZE_MAX=y" >> $config_host_mak +fi # Work around a system header bug with some kernel/XFS header # versions where they both try to define 'struct fsxattr': -- 2.7.4
