Re: [PATCH v2] Drop more useless casts from void * to pointer

[BALATON Zoltan]

On Wed, 23 Nov 2022, Markus Armbruster wrote:
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Laurent Vivier <laurent@vivier.eu>
> ---
> v2:
> * PATCH 1+2 merged as commit 0a553c12c7 and 3f7febc937
> * PATCH 3 change to util/coroutine-ucontext.c dropped [Laurent]
>
> bsd-user/elfload.c                      | 2 +-
> contrib/plugins/cache.c                 | 8 ++++----
> contrib/vhost-user-blk/vhost-user-blk.c | 2 +-
> hw/core/qdev-clock.c                    | 2 +-
> hw/hyperv/vmbus.c                       | 2 +-
> hw/net/cadence_gem.c                    | 2 +-
> hw/net/virtio-net.c                     | 2 +-
> hw/nvme/ctrl.c                          | 4 ++--
> hw/rdma/vmw/pvrdma_cmd.c                | 9 +++------
> hw/rdma/vmw/pvrdma_qp_ops.c             | 6 +++---
> hw/virtio/virtio-iommu.c                | 3 +--
> linux-user/syscall.c                    | 2 +-
> target/i386/hax/hax-all.c               | 2 +-
> tests/tcg/aarch64/system/semiheap.c     | 4 ++--
> util/vfio-helpers.c                     | 2 +-
> 15 files changed, 24 insertions(+), 28 deletions(-)
>
> diff --git a/bsd-user/elfload.c b/bsd-user/elfload.c
> index f8edb22f2a..fbcdc94b96 100644
> --- a/bsd-user/elfload.c
> +++ b/bsd-user/elfload.c
> @@ -156,7 +156,7 @@ static abi_ulong copy_elf_strings(int argc, char **argv, 
> void **page,
>             --p; --tmp; --len;
>             if (--offset < 0) {
>                 offset = p % TARGET_PAGE_SIZE;
> -                pag = (char *)page[p / TARGET_PAGE_SIZE];
> +                pag = page[p / TARGET_PAGE_SIZE];

I think arithmetic on void pointer was undefined at least in the past so 
some compilers may warn for it but not sure if this is still the case for 
the compilers we care about. Apparently not if this now compiles but that 
explains why this cast was not useless. Found some more info on this here:

https://stackoverflow.com/questions/3523145/pointer-arithmetic-for-void-pointer-in-c

Regards,
BALATON Zoltan