Re: [PATCH] cpu: Remove pointless check

On Wed, Apr 27, 2022 at 09:51:34 +0200, Martin Kletzander wrote: > These two pointers can never be NULL since they are initialised to a reference > of a struct. This became apparent when commit 210a19539447 added a VIR_DEBUG > which used both pointers because due to the concise condition the compiler saw > that if the "and" part of the condition did short-circuit (and it assumed that > can happen) the second variable would not be initialised, but it is used in the > debugging message, so the build failed with: > > In file included from ../src/cpu/cpu_x86.c:27: > ../src/cpu/cpu_x86.c: In function ‘virCPUx86DataIsIdentical’: > ../src/util/virlog.h:79:5: error: ‘bdata’ may be used uninitialized in this > function [-Werror=maybe-uninitialized] > > Fix this by just assigning the helper pointers and remove the condition > altogether. > > Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; > --- > Pushed under the build-breaker rule, but feel free to review/object. Oops! Unfortunately neither my complilers: clang version 13.0.0 (Fedora 13.0.0-3.fc35), gcc (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9) nor the CI: https://gitlab.com/pipo.sk/libvirt/-/pipelines/524030525 (besides the usual macos-11 fail) complained. Which compiler did you use?

> > src/cpu/cpu_x86.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c > index 7e9d1cea47d1..a5eac7601cad 100644 > --- a/src/cpu/cpu_x86.c > +++ b/src/cpu/cpu_x86.c > @@ -3314,10 +3314,8 @@ virCPUx86DataIsIdentical(const virCPUData *a, > return VIR_CPU_COMPARE_INCOMPATIBLE; > } > > - if (!((adata = &a->data.x86) && (bdata = &b->data.x86))) { > - VIR_DEBUG("missing x86 data: a:%p b:%p", adata, bdata); > - return VIR_CPU_COMPARE_ERROR; > - } > + adata = &a->data.x86; > + bdata = &b->data.x86; Yup, checking whether the result of the '&' operator is non-null doesn't make sense.