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>

2 files changed, 6 insertions, 6 deletions

diff --git a/rust/hw/char/pl011/src/device_class.rs b/rust/hw/char/pl011/src/device_class.rs
index 2ad80451e8..08c846aa48 100644
--- a/rust/hw/char/pl011/src/device_class.rs
+++ b/rust/hw/char/pl011/src/device_class.rs
@@ -4,7 +4,7 @@
 
 use core::ptr::NonNull;
 
-use qemu_api::{bindings::*, definitions::ObjectImpl};
+use qemu_api::{bindings::*, definitions::ObjectImpl, zeroable::Zeroable};
 
 use crate::device::PL011State;
 
@@ -12,7 +12,7 @@ use crate::device::PL011State;
 pub static VMSTATE_PL011: VMStateDescription = VMStateDescription {
     name: PL011State::TYPE_INFO.name,
     unmigratable: true,
-    ..unsafe { ::core::mem::MaybeUninit::<VMStateDescription>::zeroed().assume_init() }
+    ..Zeroable::ZERO
 };
 
 qemu_api::declare_properties! {
diff --git a/rust/hw/char/pl011/src/memory_ops.rs b/rust/hw/char/pl011/src/memory_ops.rs
index 5a5320e66c..fc69922fbf 100644
--- a/rust/hw/char/pl011/src/memory_ops.rs
+++ b/rust/hw/char/pl011/src/memory_ops.rs
@@ -2,9 +2,9 @@
 // Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
-use core::{mem::MaybeUninit, ptr::NonNull};
+use core::ptr::NonNull;
 
-use qemu_api::bindings::*;
+use qemu_api::{bindings::*, zeroable::Zeroable};
 
 use crate::device::PL011State;
 
@@ -14,11 +14,11 @@ pub static PL011_OPS: MemoryRegionOps = MemoryRegionOps {
     read_with_attrs: None,
     write_with_attrs: None,
     endianness: device_endian::DEVICE_NATIVE_ENDIAN,
-    valid: unsafe { MaybeUninit::<MemoryRegionOps__bindgen_ty_1>::zeroed().assume_init() },
+    valid: Zeroable::ZERO,
     impl_: MemoryRegionOps__bindgen_ty_2 {
         min_access_size: 4,
         max_access_size: 4,
-        ..unsafe { MaybeUninit::<MemoryRegionOps__bindgen_ty_2>::zeroed().assume_init() }
+        ..Zeroable::ZERO
     },
 };