rust: add missing const markers for MSRV==1.83.0

Rust 1.83 allows more functions to be marked const.
Fix clippy with bumped minimum supported Rust version.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250908105005.2119297-5-pbonzini@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/bits/src/lib.rs

@@ -165,19 +165,19 @@ macro_rules! bits {
 
             #[allow(dead_code)]
             #[inline(always)]
-            pub fn set(&mut self, rhs: Self) {
+            pub const fn set(&mut self, rhs: Self) {
                 self.0 |= rhs.0;
             }
 
             #[allow(dead_code)]
             #[inline(always)]
-            pub fn clear(&mut self, rhs: Self) {
+            pub const fn clear(&mut self, rhs: Self) {
                 self.0 &= !rhs.0;
             }
 
             #[allow(dead_code)]
             #[inline(always)]
-            pub fn toggle(&mut self, rhs: Self) {
+            pub const fn toggle(&mut self, rhs: Self) {
                 self.0 ^= rhs.0;
             }
 

rust/qemu-api/src/assertions.rs

@@ -81,8 +81,8 @@ macro_rules! assert_field_type {
     (@internal $param_name:ident, $ti:ty, $t:ty, $($field:tt)*) => {
         const _: () = {
             #[allow(unused)]
-            fn assert_field_type($param_name: &$t) {
-                fn types_must_be_equal<T, U>(_: &T)
+            const fn assert_field_type($param_name: &$t) {
+                const fn types_must_be_equal<T, U>(_: &T)
                 where
                     T: $crate::assertions::EqType<Itself = U>,
                 {

rust/qemu-api/src/cell.rs

@@ -980,8 +980,7 @@ impl<T> Opaque<T> {
     /// but the functions containing the dereference are usually safe.  The
     /// value returned from `uninit()` must be initialized and pinned before
     /// calling them.
-    #[allow(clippy::missing_const_for_fn)]
-    pub unsafe fn uninit() -> Self {
+    pub const unsafe fn uninit() -> Self {
         Self {
             value: UnsafeCell::new(MaybeUninit::uninit()),
             _pin: PhantomPinned,
@@ -997,8 +996,7 @@ impl<T> Opaque<T> {
     /// but the functions containing the dereference are usually safe.  The
     /// value returned from `uninit()` must be pinned (and possibly initialized)
     /// before calling them.
-    #[allow(clippy::missing_const_for_fn)]
-    pub unsafe fn zeroed() -> Self {
+    pub const unsafe fn zeroed() -> Self {
         Self {
             value: UnsafeCell::new(MaybeUninit::zeroed()),
             _pin: PhantomPinned,

rust/qemu-api/src/qom.rs

@@ -307,7 +307,7 @@ impl<T: ObjectType> ParentInit<'_, T> {
     /// Fields beyond `Object` could be uninitialized and it's your
     /// responsibility to avoid that they're used when the pointer is
     /// dereferenced, either directly or through a cast.
-    pub fn as_object_mut_ptr(&self) -> *mut bindings::Object {
+    pub const fn as_object_mut_ptr(&self) -> *mut bindings::Object {
         self.as_object_ptr().cast_mut()
     }
 
@@ -318,7 +318,7 @@ impl<T: ObjectType> ParentInit<'_, T> {
     /// Fields beyond `Object` could be uninitialized and it's your
     /// responsibility to avoid that they're used when the pointer is
     /// dereferenced, either directly or through a cast.
-    pub fn as_object_ptr(&self) -> *const bindings::Object {
+    pub const fn as_object_ptr(&self) -> *const bindings::Object {
         self.0.as_ptr().cast()
     }
 }
@@ -336,7 +336,7 @@ impl<'a, T: ObjectImpl> ParentInit<'a, T> {
     /// However, while the fields of the resulting reference are initialized,
     /// calls might use uninitialized fields of the subclass.  It is your
     /// responsibility to avoid this.
-    pub unsafe fn upcast<U: ObjectType>(&self) -> &'a U
+    pub const unsafe fn upcast<U: ObjectType>(&self) -> &'a U
     where
         T::ParentType: IsA<U>,
     {

rust/qemu-api/src/timer.rs

@@ -39,7 +39,7 @@ impl Timer {
     ///
     /// The timer must be initialized before it is armed with
     /// [`modify`](Self::modify).
-    pub unsafe fn new() -> Self {
+    pub const unsafe fn new() -> Self {
         // SAFETY: requirements relayed to callers of Timer::new
         Self(unsafe { Opaque::zeroed() })
     }

rust/qemu-api/src/uninit.rs

@@ -12,7 +12,7 @@ pub struct MaybeUninitField<'a, T, U> {
 
 impl<'a, T, U> MaybeUninitField<'a, T, U> {
     #[doc(hidden)]
-    pub fn new(parent: &'a mut MaybeUninit<T>, child: *mut U) -> Self {
+    pub const fn new(parent: &'a mut MaybeUninit<T>, child: *mut U) -> Self {
         MaybeUninitField { parent, child }
     }
 
@@ -21,7 +21,7 @@ impl<'a, T, U> MaybeUninitField<'a, T, U> {
     /// Because the `MaybeUninitField` remembers the containing object,
     /// it is possible to use it in foreign APIs that initialize the
     /// child.
-    pub fn parent(f: &Self) -> *const T {
+    pub const fn parent(f: &Self) -> *const T {
         f.parent.as_ptr()
     }
 
@@ -30,7 +30,7 @@ impl<'a, T, U> MaybeUninitField<'a, T, U> {
     /// Because the `MaybeUninitField` remembers the containing object,
     /// it is possible to use it in foreign APIs that initialize the
     /// child.
-    pub fn parent_mut(f: &mut Self) -> *mut T {
+    pub const fn parent_mut(f: &mut Self) -> *mut T {
         f.parent.as_mut_ptr()
     }
 }