| Message ID | 20220310200511.44746-1-muriloo@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block-qdict: Fix -Werror=maybe-uninitialized build failure | expand |
On 3/10/22 17:05, Murilo Opsfelder Araujo wrote: > Building QEMU on Fedora 37 (Rawhide Prerelease) ppc64le failed with the > following error: > > $ ../configure --prefix=/usr/local/qemu-disabletcg --target-list=ppc-softmmu,ppc64-softmmu --disable-tcg --disable-linux-user > ... > $ make -j$(nproc) > ... > FAILED: libqemuutil.a.p/qobject_block-qdict.c.o > cc -m64 -mlittle-endian -Ilibqemuutil.a.p -I. -I.. -Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace -Iui -Iui/shader -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/sysprof-4 -I/usr/include/lib > mount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 -I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /root/qemu/linux-headers -isystem linux-headers -iquote > . -iquote /root/qemu -iquote /root/qemu/include -iquote /root/qemu/disas/libvixl -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef -Wwrite > -strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-label > s -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi -fstack-protector-strong -fPIE -MD -MQ libqemuutil.a.p/qobject_block-qdict.c.o -MF libqemuutil.a.p/qobject_block-qdict.c.o.d - > o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c > In file included from /root/qemu/include/qapi/qmp/qdict.h:16, > from /root/qemu/include/block/qdict.h:13, > from ../qobject/block-qdict.c:11: > /root/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’: > /root/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be used uninitialized [-Werror=maybe-uninitialized] > 49 | typeof(obj) _obj = (obj); \ > | ^~~~ > ../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here > 227 | QDict *subqdict; > | ^~~~~~~~ > cc1: all warnings being treated as errors > > Fix build failure by initializing the QDict variable with NULL. > > Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> > Cc: Kevin Wolf <kwolf@redhat.com> > Cc: Hanna Reitz <hreitz@redhat.com> > Cc: Markus Armbruster <armbru@redhat.com> > --- Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com> > qobject/block-qdict.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c > index 1487cc5dd8..b26524429c 100644 > --- a/qobject/block-qdict.c > +++ b/qobject/block-qdict.c > @@ -224,7 +224,7 @@ void qdict_array_split(QDict *src, QList **dst) > for (i = 0; i < UINT_MAX; i++) { > QObject *subqobj; > bool is_subqdict; > - QDict *subqdict; > + QDict *subqdict = NULL; > char indexstr[32], prefix[32]; > size_t snprintf_ret; >
Murilo Opsfelder Araujo <muriloo@linux.ibm.com> writes: > Building QEMU on Fedora 37 (Rawhide Prerelease) ppc64le failed with the > following error: > > $ ../configure --prefix=/usr/local/qemu-disabletcg --target-list=ppc-softmmu,ppc64-softmmu --disable-tcg --disable-linux-user > ... > $ make -j$(nproc) > ... > FAILED: libqemuutil.a.p/qobject_block-qdict.c.o > cc -m64 -mlittle-endian -Ilibqemuutil.a.p -I. -I.. -Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace -Iui -Iui/shader -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/sysprof-4 -I/usr/include/lib > mount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 -I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /root/qemu/linux-headers -isystem linux-headers -iquote > . -iquote /root/qemu -iquote /root/qemu/include -iquote /root/qemu/disas/libvixl -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef -Wwrite > -strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-label > s -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi -fstack-protector-strong -fPIE -MD -MQ libqemuutil.a.p/qobject_block-qdict.c.o -MF libqemuutil.a.p/qobject_block-qdict.c.o.d - > o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c > In file included from /root/qemu/include/qapi/qmp/qdict.h:16, > from /root/qemu/include/block/qdict.h:13, > from ../qobject/block-qdict.c:11: > /root/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’: > /root/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be used uninitialized [-Werror=maybe-uninitialized] > 49 | typeof(obj) _obj = (obj); \ > | ^~~~ > ../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here > 227 | QDict *subqdict; > | ^~~~~~~~ > cc1: all warnings being treated as errors > > Fix build failure by initializing the QDict variable with NULL. > > Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> > Cc: Kevin Wolf <kwolf@redhat.com> > Cc: Hanna Reitz <hreitz@redhat.com> > Cc: Markus Armbruster <armbru@redhat.com> > --- > qobject/block-qdict.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c > index 1487cc5dd8..b26524429c 100644 > --- a/qobject/block-qdict.c > +++ b/qobject/block-qdict.c > @@ -224,7 +224,7 @@ void qdict_array_split(QDict *src, QList **dst) > for (i = 0; i < UINT_MAX; i++) { > QObject *subqobj; > bool is_subqdict; > - QDict *subqdict; > + QDict *subqdict = NULL; > char indexstr[32], prefix[32]; > size_t snprintf_ret; The compiler's warning is actually spurious. Your patch is the minimally invasive way to shut it up. But I wonder whether we can make the code clearer instead. Let's have a look: /* * There may be either a single subordinate object (named * "%u") or multiple objects (each with a key prefixed "%u."), * but not both. */ if (!subqobj == !is_subqdict) { break; Because of this, ... } if (is_subqdict) { ... subqobj is non-null here, and ... qdict_extract_subqdict(src, &subqdict, prefix); assert(qdict_size(subqdict) > 0); } else { ... null here. qobject_ref(subqobj); qdict_del(src, indexstr); } qlist_append_obj(*dst, subqobj ?: QOBJECT(subqdict)); What about this: if (is_subqdict) { qdict_extract_subqdict(src, &subqdict, prefix); assert(qdict_size(subqdict) > 0); qlist_append_obj(*dst, subqobj); } else { qobject_ref(subqobj); qdict_del(src, indexstr); qlist_append_obj(*dst, QOBJECT(subqdict)); }
Hi, Markus. On 3/11/22 06:33, Markus Armbruster wrote: > Murilo Opsfelder Araujo <muriloo@linux.ibm.com> writes: > >> Building QEMU on Fedora 37 (Rawhide Prerelease) ppc64le failed with the >> following error: >> >> $ ../configure --prefix=/usr/local/qemu-disabletcg --target-list=ppc-softmmu,ppc64-softmmu --disable-tcg --disable-linux-user >> ... >> $ make -j$(nproc) >> ... >> FAILED: libqemuutil.a.p/qobject_block-qdict.c.o >> cc -m64 -mlittle-endian -Ilibqemuutil.a.p -I. -I.. -Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace -Iui -Iui/shader -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/sysprof-4 -I/usr/include/lib >> mount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 -I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /root/qemu/linux-headers -isystem linux-headers -iquote >> . -iquote /root/qemu -iquote /root/qemu/include -iquote /root/qemu/disas/libvixl -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef -Wwrite >> -strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-label >> s -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi -fstack-protector-strong -fPIE -MD -MQ libqemuutil.a.p/qobject_block-qdict.c.o -MF libqemuutil.a.p/qobject_block-qdict.c.o.d - >> o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c >> In file included from /root/qemu/include/qapi/qmp/qdict.h:16, >> from /root/qemu/include/block/qdict.h:13, >> from ../qobject/block-qdict.c:11: >> /root/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’: >> /root/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be used uninitialized [-Werror=maybe-uninitialized] >> 49 | typeof(obj) _obj = (obj); \ >> | ^~~~ >> ../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here >> 227 | QDict *subqdict; >> | ^~~~~~~~ >> cc1: all warnings being treated as errors >> >> Fix build failure by initializing the QDict variable with NULL. >> >> Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> >> Cc: Kevin Wolf <kwolf@redhat.com> >> Cc: Hanna Reitz <hreitz@redhat.com> >> Cc: Markus Armbruster <armbru@redhat.com> >> --- >> qobject/block-qdict.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c >> index 1487cc5dd8..b26524429c 100644 >> --- a/qobject/block-qdict.c >> +++ b/qobject/block-qdict.c >> @@ -224,7 +224,7 @@ void qdict_array_split(QDict *src, QList **dst) >> for (i = 0; i < UINT_MAX; i++) { >> QObject *subqobj; >> bool is_subqdict; >> - QDict *subqdict; >> + QDict *subqdict = NULL; >> char indexstr[32], prefix[32]; >> size_t snprintf_ret; > > The compiler's warning is actually spurious. Your patch is the > minimally invasive way to shut it up. But I wonder whether we can > make the code clearer instead. Let's have a look: > > /* > * There may be either a single subordinate object (named > * "%u") or multiple objects (each with a key prefixed "%u."), > * but not both. > */ > if (!subqobj == !is_subqdict) { > break; > > Because of this, ... > > } > > if (is_subqdict) { > > ... subqobj is non-null here, and ... > > qdict_extract_subqdict(src, &subqdict, prefix); > assert(qdict_size(subqdict) > 0); > } else { > > ... null here. > > qobject_ref(subqobj); > qdict_del(src, indexstr); > } > > qlist_append_obj(*dst, subqobj ?: QOBJECT(subqdict)); > > What about this: > > if (is_subqdict) { > qdict_extract_subqdict(src, &subqdict, prefix); > assert(qdict_size(subqdict) > 0); > qlist_append_obj(*dst, subqobj); > } else { > qobject_ref(subqobj); > qdict_del(src, indexstr); > qlist_append_obj(*dst, QOBJECT(subqdict)); > } > The logic looks inverted but I think I got what you meant. I've sent a v2 with changes that made the compiler happy and also passed check-unit tests. Thank you!
diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c index 1487cc5dd8..b26524429c 100644 --- a/qobject/block-qdict.c +++ b/qobject/block-qdict.c @@ -224,7 +224,7 @@ void qdict_array_split(QDict *src, QList **dst) for (i = 0; i < UINT_MAX; i++) { QObject *subqobj; bool is_subqdict; - QDict *subqdict; + QDict *subqdict = NULL; char indexstr[32], prefix[32]; size_t snprintf_ret;
Building QEMU on Fedora 37 (Rawhide Prerelease) ppc64le failed with the following error: $ ../configure --prefix=/usr/local/qemu-disabletcg --target-list=ppc-softmmu,ppc64-softmmu --disable-tcg --disable-linux-user ... $ make -j$(nproc) ... FAILED: libqemuutil.a.p/qobject_block-qdict.c.o cc -m64 -mlittle-endian -Ilibqemuutil.a.p -I. -I.. -Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace -Iui -Iui/shader -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/sysprof-4 -I/usr/include/lib mount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 -I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /root/qemu/linux-headers -isystem linux-headers -iquote . -iquote /root/qemu -iquote /root/qemu/include -iquote /root/qemu/disas/libvixl -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef -Wwrite -strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-label s -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi -fstack-protector-strong -fPIE -MD -MQ libqemuutil.a.p/qobject_block-qdict.c.o -MF libqemuutil.a.p/qobject_block-qdict.c.o.d - o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c In file included from /root/qemu/include/qapi/qmp/qdict.h:16, from /root/qemu/include/block/qdict.h:13, from ../qobject/block-qdict.c:11: /root/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’: /root/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be used uninitialized [-Werror=maybe-uninitialized] 49 | typeof(obj) _obj = (obj); \ | ^~~~ ../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here 227 | QDict *subqdict; | ^~~~~~~~ cc1: all warnings being treated as errors Fix build failure by initializing the QDict variable with NULL. Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> Cc: Kevin Wolf <kwolf@redhat.com> Cc: Hanna Reitz <hreitz@redhat.com> Cc: Markus Armbruster <armbru@redhat.com> --- qobject/block-qdict.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)