Re: [PATCH v2] block-qdict: Fix -Werror=maybe-uninitialized build failure

[Murilo Opsfelder Araújo]

Hi, Philippe.

On Monday, March 14, 2022 10:47:11 AM -03 Philippe Mathieu-Daudé wrote:
> On 11/3/22 23:16, 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
>
> This part >>>
>
> >      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
>
> <<< is noise (doesn't provide any value) and could be stripped.

Is this something the committer/maintainer could edit when applying the commit
or do you need I resend the v3?

Cheers!

>
> >      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 expanding the ternary operation.
> > Tested with `make check-unit` (the check-block-qdict test passed).
> >
> > 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>
> > ---
> > v1: https://lists.nongnu.org/archive/html/qemu-devel/2022-03/msg03224.html
> >
> >   qobject/block-qdict.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
> > index 1487cc5dd8..4a83bda2c3 100644
> > --- a/qobject/block-qdict.c
> > +++ b/qobject/block-qdict.c
> > @@ -251,12 +251,12 @@ void qdict_array_split(QDict *src, QList **dst)
> >           if (is_subqdict) {
> >               qdict_extract_subqdict(src, &subqdict, prefix);
> >               assert(qdict_size(subqdict) > 0);
> > +            qlist_append_obj(*dst, QOBJECT(subqdict));
> >           } else {
> >               qobject_ref(subqobj);
> >               qdict_del(src, indexstr);
> > +            qlist_append_obj(*dst, subqobj);
> >           }
> > -
> > -        qlist_append_obj(*dst, subqobj ?: QOBJECT(subqdict));
> >       }
> >   }
> >
>
>
>
>

--
Murilo