Re: [PATCH 1/2] rust: Add antoher variant for impl_vmstate_struct! macro

[Martin Kletzander <mkletzan@redhat.com>]

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On Mon, Aug 04, 2025 at 12:08:15PM +0200, Paolo Bonzini wrote:
>Il lun 4 ago 2025, 10:56 Martin Kletzander <mkletzan@redhat.com> ha scritto:
>
>> *BUT* of course I had to rebase the patches on top of current rust-next
>> on Friday and there were some of your commits from Thursday which I now
>> see actually fix all what I tried fixing before as well.  I tried
>> finding the previous commit on which I saw all the issues and after some
>> rebuilding I could not.  So it is now not even broken on rust-next.
>>
>> This way I completely wasted your time, but at least learned something
>> that's happening in the code.  Sorry for that.
>>
>
>Uh no you didn't. It was broken.
>

But it is not now, neither master, nor rust-next, nor anything I tried
from the reflog, which makes me suspicious about what I was developing
this on.  I distinctly remember the `$vmsd.get()` call in the macro
which I presume was causing the copying due to VMStateDescription
automatically implementing the Copy trait due to the bindgen invocation.

But that's nowhere to be found, including git log --walk-reflog and
manually searching various history trees.  And I doubted that you
rewrote the history of the rust-next branch.  Neither do I remember
changing the macro until I found out that other in code changes did not
help to fix it.

After some time I now managed to find it.  It was the previous version
of a commit 4cb0670e12c4, and that is nowhere to be found in rust-next
at the moment, I guess fixes were incorporated while rebasing the branch
on current master.

That was a wild ride, but I'm glad it all works (apart from the bash
version indentation) on rust-next.  I'll try to read up on what's next
to help with, if anything.

Have a nice day,
Martin

>Paolo
>
>Martin
>>
>> >Paolo
>> >
>> > rust/qemu-api/src/vmstate.rs         | 11 +++++++++++
>> >>  rust/qemu-api/tests/vmstate_tests.rs |  1 +
>> >>  2 files changed, 12 insertions(+)
>> >>
>> >> diff --git a/rust/qemu-api/src/vmstate.rs b/rust/qemu-api/src/
>> vmstate.rs
>> >> index b5c6b764fbba..716e52afe740 100644
>> >> --- a/rust/qemu-api/src/vmstate.rs
>> >> +++ b/rust/qemu-api/src/vmstate.rs
>> >> @@ -449,6 +449,17 @@ macro_rules! vmstate_validate {
>> >>  /// description of the struct.
>> >>  #[macro_export]
>> >>  macro_rules! impl_vmstate_struct {
>> >> +    ($type:ty, $(&)?$vmsd:ident) => {
>> >> +        unsafe impl $crate::vmstate::VMState for $type {
>> >> +            const BASE: $crate::bindings::VMStateField =
>> >> +                $crate::bindings::VMStateField {
>> >> +                    vmsd: $vmsd.as_ref(),
>> >> +                    size: ::core::mem::size_of::<$type>(),
>> >> +                    flags: $crate::bindings::VMStateFlags::VMS_STRUCT,
>> >> +                    ..$crate::zeroable::Zeroable::ZERO
>> >> +                };
>> >> +        }
>> >> +    };
>> >>      ($type:ty, $vmsd:expr) => {
>> >>          unsafe impl $crate::vmstate::VMState for $type {
>> >>              const BASE: $crate::bindings::VMStateField = {
>> >> diff --git a/rust/qemu-api/tests/vmstate_tests.rs
>> b/rust/qemu-api/tests/
>> >> vmstate_tests.rs
>> >> index 2c0670ba0eed..7d3180e6c2ea 100644
>> >> --- a/rust/qemu-api/tests/vmstate_tests.rs
>> >> +++ b/rust/qemu-api/tests/vmstate_tests.rs
>> >> @@ -320,6 +320,7 @@ fn test_vmstate_struct_varray_uint8_wrapper() {
>> >>          b"arr_a_wrap\0"
>> >>      );
>> >>      assert_eq!(foo_fields[5].num_offset, 228);
>> >> +    assert_eq!(foo_fields[5].vmsd, VMSTATE_FOOA.as_ref());
>> >>      assert!(unsafe { foo_fields[5].field_exists.unwrap()(foo_b_p, 0)
>> });
>> >>
>> >>      // The last VMStateField in VMSTATE_FOOB.
>> >> --
>> >> 2.50.1
>> >>
>> >>
>>

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