Re: [v3] Help wanted for enabling -Wshadow=local

[Markus Armbruster <armbru@redhat.com>]

Markus Armbruster <armbru@redhat.com> writes:

> Local variables shadowing other local variables or parameters make the
> code needlessly hard to understand.  Bugs love to hide in such code.
> Evidence: "[PATCH v3 1/7] migration/rdma: Fix save_page method to fail
> on polling error".
>
> Enabling -Wshadow would prevent bugs like this one.  But we have to
> clean up all the offenders first.
>
> Quite a few people responded to my calls for help.  Thank you so much!
>
> I'm collecting patches in my git repo at
> https://repo.or.cz/qemu/armbru.git in branch shadow-next.  All but the
> last two are in a pending pull request.
>
> My test build is down to seven files with warnings.  "[PATCH v2 0/3]
> hexagon: GETPC() and shadowing fixes" takes care of four, but it needs a
> rebase.
>
> Remaining three:
>
>     In file included from ../hw/display/virtio-gpu-virgl.c:19:
>     ../hw/display/virtio-gpu-virgl.c: In function ‘virgl_cmd_submit_3d’:
>     /work/armbru/qemu/include/hw/virtio/virtio-gpu.h:228:16: warning: declaration of ‘s’ shadows a previous local [-Wshadow=compatible-local]
>       228 |         size_t s;                                                       \
>           |                ^
>     ../hw/display/virtio-gpu-virgl.c:215:5: note: in expansion of macro ‘VIRTIO_GPU_FILL_CMD’
>       215 |     VIRTIO_GPU_FILL_CMD(cs);
>           |     ^~~~~~~~~~~~~~~~~~~
>     ../hw/display/virtio-gpu-virgl.c:213:12: note: shadowed declaration is here
>       213 |     size_t s;
>           |            ^
>
>     In file included from ../contrib/vhost-user-gpu/virgl.h:18,
>                      from ../contrib/vhost-user-gpu/virgl.c:17:
>     ../contrib/vhost-user-gpu/virgl.c: In function ‘virgl_cmd_submit_3d’:
>     ../contrib/vhost-user-gpu/vugpu.h:167:16: warning: declaration of ‘s’ shadows a previous local [-Wshadow=compatible-local]
>       167 |         size_t s;                                               \
>           |                ^
>     ../contrib/vhost-user-gpu/virgl.c:203:5: note: in expansion of macro ‘VUGPU_FILL_CMD’
>       203 |     VUGPU_FILL_CMD(cs);
>           |     ^~~~~~~~~~~~~~
>     ../contrib/vhost-user-gpu/virgl.c:201:12: note: shadowed declaration is here
>       201 |     size_t s;
>           |            ^
>
>     ../contrib/vhost-user-gpu/vhost-user-gpu.c: In function ‘vg_resource_flush’:
>     ../contrib/vhost-user-gpu/vhost-user-gpu.c:837:29: warning: declaration of ‘i’ shadows a previous local [-Wshadow=local]
>       837 |             pixman_image_t *i =
>           |                             ^
>     ../contrib/vhost-user-gpu/vhost-user-gpu.c:757:9: note: shadowed declaration is here
>       757 |     int i;
>           |         ^
>
> Gerd, Marc-André, or anybody else?

Thomas posted patches:

    [PATCH] hw/virtio/virtio-gpu: Fix compiler warning when compiling with -Wshadow
    [PATCH] contrib/vhost-user-gpu: Fix compiler warning when compiling with -Wshadow

> More warnings may lurk in code my test build doesn't compile.  Need a
> full CI build with -Wshadow=local to find them.  Anybody care to kick
> one off?

Thomas did; see his reply downthread.

Thank you, Thomas!