Re: [PATCH] async: Suppress GCC13 false positive in aio_bh_poll()

[Thomas Huth]

On 20/04/2023 22.29, Cédric Le Goater wrote:
> From: Cédric Le Goater <clg@redhat.com>
>
> GCC13 reports an error :
>
> ../util/async.c: In function ‘aio_bh_poll’:
> include/qemu/queue.h:303:22: error: storing the address of local variable 
> ‘slice’ in ‘*ctx.bh_slice_list.sqh_last’ [-Werror=dangling-pointer=]
>    303 |     (head)->sqh_last = &(elm)->field.sqe_next;                         
>  \
>        |     ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
> ../util/async.c:169:5: note: in expansion of macro ‘QSIMPLEQ_INSERT_TAIL’
>    169 |     QSIMPLEQ_INSERT_TAIL(&ctx->bh_slice_list, &slice, next);
>        |     ^~~~~~~~~~~~~~~~~~~~
> ../util/async.c:161:17: note: ‘slice’ declared here
>    161 |     BHListSlice slice;
>        |                 ^~~~~
> ../util/async.c:161:17: note: ‘ctx’ declared here
>
> But the local variable 'slice' is removed from the global context list
> in following loop of the same routine. Add a pragma to silent GCC.

I think this should also go into the next stable release (now on CC:), we're 
already getting bug reports about this:

 https://gitlab.com/qemu-project/qemu/-/issues/1655

 Thomas