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

[Daniel P . Berrangé]

On Wed, Nov 23, 2022 at 02:51:49PM +0100, BALATON Zoltan wrote:
> 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

QEMU explicitly only targets GCC + Clang, so portability to other
compilers is not required.

With regards,
Daniel
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