Re: [PATCH v2 00/13] rust: miscellaneous cleanups + QOM integration tests

[Paolo Bonzini <pbonzini@redhat.com>]

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Il mar 22 ott 2024, 22:46 Kevin Wolf <kwolf@redhat.com> ha scritto:

> Am 21.10.2024 um 18:35 hat Paolo Bonzini geschrieben:
> > This series integrates some of the observations from the MSRV patches at
> >
> https://lore.kernel.org/qemu-devel/20241015131735.518771-1-pbonzini@redhat.com/
> .
> >
> > The main changes here are two: first, build an integration test that
> > actually tries to create a QOM object that is defined by Rust code;
> > second, make the properties array immutable so that declare_properties!
> > is enforced to use only const-friendly constructs.  These are patches
> > 6-11; the others consist of small cleanups.
> >
> > Hidden in here is actually a C patch (#10) which makes the
> > bindgen-generated prototypes use "*const" instead of "*mut".
> >
> > Tested with Rust nightly and (together with more patches from the
> > RFC), with Rust 1.63.0.
> >
> > Unlike the MSRV patches, this should be ready for inclusion; the
> > changes should be mostly uncontroversial.
>
> I'm not convinced that Zeroable has sufficient justification when all it
> does is saving us a few lines of code at the expense of making things
> more implicit


Implicit zero fields are used a lot in C code, including in
VMStateDescription and various const vtable structs, so I think we need
something of equivalent brevity.

There could be other solutions, for example a more generic
ConstDefault::DEFAULT trait. For now I went for something that resembles
existing code, as well as the C code we're converting.

. But it's used correctly as far as I can tell, so:
>
> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
>

Thanks!

Paolo


>

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