From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47649) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1btbix-0000dv-Rf for qemu-devel@nongnu.org; Mon, 10 Oct 2016 10:38:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1btbiw-00088C-H5 for qemu-devel@nongnu.org; Mon, 10 Oct 2016 10:38:39 -0400 From: Eric Blake Date: Mon, 10 Oct 2016 09:38:26 -0500 Message-Id: <1476110306-23754-1-git-send-email-eblake@redhat.com> Subject: [Qemu-devel] [PATCH v2] build: Work around SIZE_MAX bug in OSX headers List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, kwolf@redhat.com, armbru@redhat.com, peter.maydell@linaro.org, ashijeetacharya@gmail.com 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. 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 --- 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) I lack easy access to a Mac box, so this is untested as to whether it actually solves the issue... --- include/qemu/osdep.h | 8 ++++++++ configure | 13 +++++++++++++ 2 files changed, 21 insertions(+) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 9e9fa61..22667f6 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 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. */ +#ifdef SIZE_MAX_BROKEN +#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..137ebb8 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 +#include +int main(int argc, char *argv[]) { + return printf("%zu", SIZE_MAX); +} +EOF + +if ! compile_object -Werror ; then + QEMU_CFLAGS="-DSIZE_MAX_BROKEN $QEMU_CFLAGS" +fi + ########################################## # L2TPV3 probe -- 2.7.4