rust: provide safe wrapper for MaybeUninit::zeroed()

MaybeUninit::zeroed() is handy, but it introduces unsafe (and has a
pretty heavy syntax in general).  Introduce a trait that provides the
same functionality while staying within safe Rust.

In addition, MaybeUninit::zeroed() is not available as a "const"
function until Rust 1.75.0, so this also prepares for having handwritten
implementations of the trait until we can assume that version.

Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2024-10-18 10:51:10 +02:00
parent c92c447ff0
commit 6e50bde1e1
6 changed files with 35 additions and 10 deletions

View file

@ -31,7 +31,7 @@ macro_rules! define_property {
offset: ::core::mem::offset_of!($state, $field) as isize,
set_default: true,
defval: $crate::bindings::Property__bindgen_ty_1 { u: $defval as u64 },
..unsafe { ::core::mem::MaybeUninit::<$crate::bindings::Property>::zeroed().assume_init() }
..$crate::zeroable::Zeroable::ZERO
}
};
($name:expr, $state:ty, $field:expr, $prop:expr, $type:expr$(,)*) => {
@ -41,7 +41,7 @@ macro_rules! define_property {
info: $prop,
offset: ::core::mem::offset_of!($state, $field) as isize,
set_default: false,
..unsafe { ::core::mem::MaybeUninit::<$crate::bindings::Property>::zeroed().assume_init() }
..$crate::zeroable::Zeroable::ZERO
}
};
}
@ -58,7 +58,7 @@ macro_rules! declare_properties {
len
}] = [
$($prop),*,
unsafe { ::core::mem::MaybeUninit::<$crate::bindings::Property>::zeroed().assume_init() },
$crate::zeroable::Zeroable::ZERO,
];
};
}
@ -79,7 +79,7 @@ macro_rules! vm_state_description {
$vname.as_ptr()
},)*
unmigratable: true,
..unsafe { ::core::mem::MaybeUninit::<$crate::bindings::VMStateDescription>::zeroed().assume_init() }
..$crate::zeroable::Zeroable::ZERO
};
}
}