Re: Clang warning in drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
From: Alex Deucher
Date: Thu Mar 21 2019 - 00:44:27 EST
On Wed, Mar 20, 2019 at 4:49 PM Nick Desaulniers
> On Wed, Mar 20, 2019 at 2:37 AM Koenig, Christian
> <Christian.Koenig@xxxxxxx> wrote:
> > Am 20.03.19 um 05:34 schrieb Nathan Chancellor:
> > > On Wed, Mar 20, 2019 at 01:31:27AM +0000, Pan, Xinhui wrote:
> > >> these two enumerated types are same for now. both of them might change in the future.
> Please consider if the YAGNI principle applies here.
> > >>
> > >> I have not used clang, but would .block_id = (int)head->block fix your warning? If such change is acceptable, I can make one then.
> My preference on solutions, in order:
> 1. One enum (this is the simplest most type safe solution). Add
> another enum when you actually need it. Otherwise, YAGNI.
It make sense to have two enums. One is a firmware interface that is
only used by some asics and the other is for the general driver
interface (non-asic specific for the ras features.
> 2. Safe casting function (like the one Nathan supplied, maybe with
> WARN_ONCE rather than WARN). This ensures that at least if the types
> diverge you get a runtime warning. A compile-time warning would be
> preferred, but I haven't taken the time to think through how that
> might be implemented.
I'd prefer this one.
> 3. Cast to int (this has been used in other places throughout the
> kernel, but provides the weakest type safety and doesn't catch future
> 4. Disabling the warning. (I almost never advocate for this).
> > Another question is if it is such a good idea to just silence the warning?
> For the kernel, it seems that each maintainer can choose what to apply
> to their subsystem. I would recommend against disabling additional
> warnings that aren't disable kernel-wide for most cases.
> -Wenum-conversion has spotted many bugs. While the enums in question
> today are not different, they MIGHT eventually diverge and lead to
> bugs, like the others we've found and fixed throughout the kernel. So
> I would recommend fixing now, and be insulated in the future.
> ~Nick Desaulniers
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