| Message ID | 20160807012545.7145-1-bobby.prani@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/08/2016 03:25, Pranith Kumar wrote: > Clang produces the following warning. The warning is detailed here: > https://reviews.llvm.org/D15866 > > /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> > --- > include/ui/qemu-spice.h | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/include/ui/qemu-spice.h b/include/ui/qemu-spice.h > index edad5e7..3979a1e 100644 > --- a/include/ui/qemu-spice.h > +++ b/include/ui/qemu-spice.h > @@ -42,8 +42,7 @@ int qemu_spice_set_pw_expire(time_t expires); > int qemu_spice_migrate_info(const char *hostname, int port, int tls_port, > const char *subject); > > -#define SPICE_NEEDS_SET_MM_TIME \ > - (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) > +#define SPICE_NEEDS_SET_MM_TIME (SPICE_SERVER_VERSION < 0xc06) > > #if SPICE_SERVER_VERSION >= 0x000c02 > void qemu_spice_register_ports(void); > If SPICE_SERVER_VERSION is not defined, the preprocessor will give it value 0 so there is no semantic change. Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Paolo
On 07/08/2016 03:25, Pranith Kumar wrote: > Clang produces the following warning. The warning is detailed here: > https://reviews.llvm.org/D15866 > > /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> > --- > include/ui/qemu-spice.h | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/include/ui/qemu-spice.h b/include/ui/qemu-spice.h > index edad5e7..3979a1e 100644 > --- a/include/ui/qemu-spice.h > +++ b/include/ui/qemu-spice.h > @@ -42,8 +42,7 @@ int qemu_spice_set_pw_expire(time_t expires); > int qemu_spice_migrate_info(const char *hostname, int port, int tls_port, > const char *subject); > > -#define SPICE_NEEDS_SET_MM_TIME \ > - (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) > +#define SPICE_NEEDS_SET_MM_TIME (SPICE_SERVER_VERSION < 0xc06) > > #if SPICE_SERVER_VERSION >= 0x000c02 > void qemu_spice_register_ports(void); > Hmm, no, the patch is not okay because we use -Wundef. The GCC manual says: If the 'defined' operator appears as a result of a macro expansion, the C standard says the behavior is undefined. GNU cpp treats it as a genuine 'defined' operator and evaluates it normally. It will warn wherever your code uses this feature if you use the command-line option '-pedantic', since other compilers may handle it differently. So this is another instance of clang putting warnings in the wrong category. Please add -Wno-expansion-to-defined instead. Paolo
diff --git a/include/ui/qemu-spice.h b/include/ui/qemu-spice.h index edad5e7..3979a1e 100644 --- a/include/ui/qemu-spice.h +++ b/include/ui/qemu-spice.h @@ -42,8 +42,7 @@ int qemu_spice_set_pw_expire(time_t expires); int qemu_spice_migrate_info(const char *hostname, int port, int tls_port, const char *subject); -#define SPICE_NEEDS_SET_MM_TIME \ - (!defined(SPICE_SERVER_VERSION) || (SPICE_SERVER_VERSION < 0xc06)) +#define SPICE_NEEDS_SET_MM_TIME (SPICE_SERVER_VERSION < 0xc06) #if SPICE_SERVER_VERSION >= 0x000c02 void qemu_spice_register_ports(void);
Clang produces the following warning. The warning is detailed here: https://reviews.llvm.org/D15866 /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> --- include/ui/qemu-spice.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)