| Message ID | 20160809023545.30204-1-bobby.prani@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/08/2016 04:35, Pranith Kumar wrote: > Clang produces the following warning. The warning is detailed here: > https://reviews.llvm.org/D15866. Disable the warning. > > /home/pranith/devops/code/qemu/hw/display/qxl.c:507:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] > #if SPICE_NEEDS_SET_MM_TIME > ^ > /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' > (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) > ^ > /home/pranith/devops/code/qemu/hw/display/qxl.c:1074:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] > #if SPICE_NEEDS_SET_MM_TIME > ^ > /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' > (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) > > Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> > --- > configure | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/configure b/configure > index f57fcc6..a1a6e3f 100755 > --- a/configure > +++ b/configure > @@ -3025,6 +3025,19 @@ if ! compile_prog "$glib_cflags -Werror" "$glib_libs" ; then > fi > fi > > +# Silence clang warnings about expansion to 'defined' in macro > +cat > $TMPC << EOF > +#define TEST (defined(DUMMY)) > +#if TEST > +int main(void) { return 0; } > +#endif > +EOF > +if ! compile_prog "-Werror" ; then > + if cc_has_warning_flag "-Wno-expansion-to-defined"; then > + CFLAGS="-Wno-expansion-to-defined $CFLAGS" > + fi > +fi > + > ########################################## > # SHA command probe for modules > if test "$modules" = yes; then > Can you just add it to gcc_flags instead? Thanks, Paolo
On 9 August 2016 at 03:35, Pranith Kumar <bobby.prani@gmail.com> wrote: > Clang produces the following warning. The warning is detailed here: > https://reviews.llvm.org/D15866. Disable the warning. > > /home/pranith/devops/code/qemu/hw/display/qxl.c:507:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] > #if SPICE_NEEDS_SET_MM_TIME > ^ > /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' > (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) > ^ > /home/pranith/devops/code/qemu/hw/display/qxl.c:1074:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] > #if SPICE_NEEDS_SET_MM_TIME > ^ > /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' > (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) Is this the only thing in our code which provokes the warning? If so, why don't we just fix it to not be undefined behaviour? thanks -- PMM
On Tue, Aug 09, 2016 at 09:09:13AM +0100, Peter Maydell wrote: > On 9 August 2016 at 03:35, Pranith Kumar <bobby.prani@gmail.com> wrote: > > Clang produces the following warning. The warning is detailed here: > > https://reviews.llvm.org/D15866. Disable the warning. > > > > /home/pranith/devops/code/qemu/hw/display/qxl.c:507:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] > > #if SPICE_NEEDS_SET_MM_TIME > > ^ > > /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' > > (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) > > ^ > > /home/pranith/devops/code/qemu/hw/display/qxl.c:1074:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] > > #if SPICE_NEEDS_SET_MM_TIME > > ^ > > /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' > > (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) > > Is this the only thing in our code which provokes the warning? > If so, why don't we just fix it to not be undefined behaviour? Indeed, it looks like it could be fixed by changing include/ui/qemu-spice.h #define SPICE_NEEDS_SET_MM_TIME \ (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) to be #if !defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06) #define SPICE_NEEDS_SET_MM_TIME #endif Regards, Daniel
On 09/08/2016 10:09, Peter Maydell wrote: > On 9 August 2016 at 03:35, Pranith Kumar <bobby.prani@gmail.com> wrote: >> Clang produces the following warning. The warning is detailed here: >> https://reviews.llvm.org/D15866. Disable the warning. >> >> /home/pranith/devops/code/qemu/hw/display/qxl.c:507:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] >> #if SPICE_NEEDS_SET_MM_TIME >> ^ >> /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' >> (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) >> ^ >> /home/pranith/devops/code/qemu/hw/display/qxl.c:1074:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] >> #if SPICE_NEEDS_SET_MM_TIME >> ^ >> /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' >> (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) > > Is this the only thing in our code which provokes the warning? > If so, why don't we just fix it to not be undefined behaviour? Indeed that was my first suggestion yesterday. However, we use -Wundef (a good idea, I think), and fixing it would cause the -Wundef warning to appear instead. Paolo
On 9 August 2016 at 09:15, Paolo Bonzini <pbonzini@redhat.com> wrote: > > > On 09/08/2016 10:09, Peter Maydell wrote: >> Is this the only thing in our code which provokes the warning? >> If so, why don't we just fix it to not be undefined behaviour? > > Indeed that was my first suggestion yesterday. However, we use -Wundef > (a good idea, I think), and fixing it would cause the -Wundef warning to > appear instead. Why would #if !defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06) #define SPICE_NEEDS_SET_MM_TIME 1 #else #define SPICE_NEEDS_SET_MM_TIME 0 #endif provoke a Wundef warning? thanks -- PMM
On 09/08/2016 10:17, Peter Maydell wrote: > On 9 August 2016 at 09:15, Paolo Bonzini <pbonzini@redhat.com> wrote: >> >> >> On 09/08/2016 10:09, Peter Maydell wrote: >>> Is this the only thing in our code which provokes the warning? >>> If so, why don't we just fix it to not be undefined behaviour? >> >> Indeed that was my first suggestion yesterday. However, we use -Wundef >> (a good idea, I think), and fixing it would cause the -Wundef warning to >> appear instead. > > Why would > #if !defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06) > #define SPICE_NEEDS_SET_MM_TIME 1 > #else > #define SPICE_NEEDS_SET_MM_TIME 0 > #endif > > provoke a Wundef warning? Oh, that would work indeed. I was thinking of simplifying the definition of SPICE_NEEDS_SET_MM_TIME like this: #define SPICE_NEEDS_SET_MM_TIME (SPICE_SERVER_VERSION < 0xc06) If we do this, it would make sense to add -Wexpansion-to-defined to GCC and enable it (though I still believe it's wrong to add it to -Wall). Thanks, Paolo
On Tue, Aug 9, 2016 at 4:17 AM, Peter Maydell <peter.maydell@linaro.org> wrote: > #if !defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06) > #define SPICE_NEEDS_SET_MM_TIME 1 > #else > #define SPICE_NEEDS_SET_MM_TIME 0 > #endif > This looks better. I will fix up a patch.
diff --git a/configure b/configure index f57fcc6..a1a6e3f 100755 --- a/configure +++ b/configure @@ -3025,6 +3025,19 @@ if ! compile_prog "$glib_cflags -Werror" "$glib_libs" ; then fi fi +# Silence clang warnings about expansion to 'defined' in macro +cat > $TMPC << EOF +#define TEST (defined(DUMMY)) +#if TEST +int main(void) { return 0; } +#endif +EOF +if ! compile_prog "-Werror" ; then + if cc_has_warning_flag "-Wno-expansion-to-defined"; then + CFLAGS="-Wno-expansion-to-defined $CFLAGS" + fi +fi + ########################################## # SHA command probe for modules if test "$modules" = yes; then
Clang produces the following warning. The warning is detailed here: https://reviews.llvm.org/D15866. Disable the warning. /home/pranith/devops/code/qemu/hw/display/qxl.c:507:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] #if SPICE_NEEDS_SET_MM_TIME ^ /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) ^ /home/pranith/devops/code/qemu/hw/display/qxl.c:1074:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined] #if SPICE_NEEDS_SET_MM_TIME ^ /home/pranith/devops/code/qemu/include/ui/qemu-spice.h:46:5: note: expanded from macro 'SPICE_NEEDS_SET_MM_TIME' (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> --- configure | 13 +++++++++++++ 1 file changed, 13 insertions(+)