On 09/09/2020 08:49, Andriy Gapon wrote:
> On 08/09/2020 15:48, Mark Johnston wrote:
>> I observed the same thing recently as well: the compiler catches
>> uninitialized variables only in simple cases. In my case, any uses of
>> goto within the function seemed to silence the warning, even if they
>> appeared after the uninitialized reference.
>
> I am running a kernel build now with this addition (for clang):
> CWARNEXTRA+= -Wconditional-uninitialized
> -Wno-error-conditional-uninitialized
>
> It produces a ton of warnings.
> Some of them are probably false positives, but some look quite reasonable.
>
> E.g.:
> sys/cam/cam_periph.c:314:19: warning: variable 'p_drv' may be uninitialized
> when
> used here [-Wconditional-uninitialized]
> TAILQ_REMOVE(&(*p_drv)->units, periph, unit_links);
>
> Indeed, there is a conditional 'goto failure' before a first assignment to
> p_drv
> and the line is after the label. So, maybe the situation is impossible, but
> it
> is reasonable to warn about it.
>
> But the number of false positives (and "possible but impossible" situations)
> is
> too overwhelming.
But but:
/usr/devel/git//sys/cam/mmc/mmc_da.c:1824:6: warning: variable 'part_index' may
be uninitialized when used here [-Wconditional-uninitialized]
if (part_index != softc->part_curr) {
^~~~~~~~~~
/usr/devel/git//sys/cam/mmc/mmc_da.c:1800:16: note: initialize the variable
'part_index' to silence this warning
int part_index;
^
= 0
1 warning generated.
There are useful true positives as well.
--
Andriy Gapon
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