rust: add IsA bounds to QOM implementation traits

Check that the right bounds are provided to the qom_isa! macro
whenever the class is defined to implement a certain class.
This removes the need to add IsA<> bounds together with the
*Impl trait bounds.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 4 insertions, 2 deletions

diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs
index 3a7aa4d..c4dd26b 100644
--- a/rust/qemu-api/src/qdev.rs
+++ b/rust/qemu-api/src/qdev.rs
@@ -86,7 +86,7 @@ unsafe extern "C" fn rust_resettable_exit_fn<T: ResettablePhasesImpl>(
 }
 
 /// Trait providing the contents of [`DeviceClass`].
-pub trait DeviceImpl: ObjectImpl + ResettablePhasesImpl {
+pub trait DeviceImpl: ObjectImpl + ResettablePhasesImpl + IsA<DeviceState> {
     /// _Realization_ is the second stage of device creation. It contains
     /// all operations that depend on device properties and can fail (note:
     /// this is not yet supported for Rust devices).
diff --git a/rust/qemu-api/src/qom.rs b/rust/qemu-api/src/qom.rs
index 3d5ab2d..10ce359 100644
--- a/rust/qemu-api/src/qom.rs
+++ b/rust/qemu-api/src/qom.rs
@@ -37,6 +37,8 @@
 //! * a trait for virtual method implementations, for example `DeviceImpl`.
 //!   Child classes implement this trait to provide their own behavior for
 //!   virtual methods. The trait's methods take `&self` to access instance data.
+//!   The traits have the appropriate specialization of `IsA<>` as a supertrait,
+//!   for example `IsA<DeviceState>` for `DeviceImpl`.
 //!
 //! * an implementation of [`ClassInitImpl`], for example
 //!   `ClassInitImpl<DeviceClass>`. This fills the vtable in the class struct;
@@ -497,7 +499,7 @@ impl<T: ObjectType> ObjectDeref for &mut T {}
 impl<T: ObjectType> ObjectCastMut for &mut T {}
 
 /// Trait a type must implement to be registered with QEMU.
-pub trait ObjectImpl: ObjectType + ClassInitImpl<Self::Class> {
+pub trait ObjectImpl: ObjectType + ClassInitImpl<Self::Class> + IsA<Object> {
     /// The parent of the type.  This should match the first field of the
     /// struct that implements `ObjectImpl`, minus the `ParentField<_>` wrapper.
     type ParentType: ObjectType;