On 06/10/2023 16.45, Markus Armbruster wrote:
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?
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?
I ran a build here (with -Werror enabled, so that it's easier to see where
it breaks):
https://gitlab.com/thuth/qemu/-/pipelines/1028023489
... but I didn't see any additional spots in the logs beside the ones that
you already listed.
Thomas
