perf: move downcast out of trait

it is only used internally and should not be shared as much.
While removing this from the trait is technically breaking its not changing the behaviour and isnt used by ksc so it can be changed relatively easily.

This allows it to change the arguments reducing the amount of clones.

Author: EdJoPaTo

src/lib.rs

@@ -195,8 +195,8 @@ pub trait KStruct: Default {
         _parent: Option<SharedType<Output::Parent>>,
     ) -> KResult<OptRc<Output>> {
         let output = OptRc::from(Output::default());
-        let root = Self::downcast(_root, output.clone(), true);
-        let parent = Self::downcast(_parent, output.clone(), false);
+        let root = downcast(_root, &output, true);
+        let parent = downcast(_parent, &output, false);
         Output::read(&output, _io, root, parent)?;
         Ok(output)
     }
@@ -211,43 +211,39 @@ pub trait KStruct: Default {
         let mut output = OptRc::from(Output::default());
         init(Rc::get_mut(output.get_mut()).unwrap())?;
 
-        let root = Self::downcast(_root, output.clone(), true);
-        let parent = Self::downcast(_parent, output.clone(), false);
+        let root = downcast(_root, &output, true);
+        let parent = downcast(_parent, &output, false);
         Output::read(&output, _io, root, parent)?;
         Ok(output)
     }
+}
 
-    fn downcast<T, U>(
-        opt_rc: Option<SharedType<U>>,
-        fallback: OptRc<T>,
-        panic: bool,
-    ) -> SharedType<U>
-    where
-        T: KStruct + Default + Any,
-        U: 'static,
-    {
-        if let Some(rc) = opt_rc {
-            rc
+fn downcast<T, U>(opt_rc: Option<SharedType<U>>, fallback: &OptRc<T>, panic: bool) -> SharedType<U>
+where
+    T: KStruct + Default + Any,
+    U: 'static,
+{
+    if let Some(rc) = opt_rc {
+        rc
+    } else {
+        let fallback_any: &dyn Any = &fallback.get();
+        //println!("`{}` is a '{}' type", type_name_of_val(&t), type_name::<Rc<U>>());
+        if let Some(as_result) = fallback_any.downcast_ref::<Rc<U>>() {
+            SharedType::<U>::new(as_result.clone())
         } else {
-            let fallback_any: &dyn Any = &fallback.get();
-            //println!("`{}` is a '{}' type", type_name_of_val(&t), type_name::<Rc<U>>());
-            if let Some(as_result) = fallback_any.downcast_ref::<Rc<U>>() {
-                SharedType::<U>::new(as_result.clone())
-            } else {
-                #[allow(clippy::incompatible_msrv)] // behind feature flag
-                #[allow(clippy::manual_assert)]
-                if panic {
-                    #[cfg(feature = "type_name_of_val")]
-                    panic!(
-                        "`{}` is not a '{}' type",
-                        std::any::type_name_of_val(&fallback),
-                        type_name::<Rc<U>>()
-                    );
-                    #[cfg(not(feature = "type_name_of_val"))]
-                    panic!("`{:p}` is not a '{}' type", &fallback, type_name::<Rc<U>>());
-                }
-                SharedType::<U>::empty()
+            #[allow(clippy::incompatible_msrv)] // behind feature flag
+            #[allow(clippy::manual_assert)]
+            if panic {
+                #[cfg(feature = "type_name_of_val")]
+                panic!(
+                    "`{}` is not a '{}' type",
+                    std::any::type_name_of_val(&fallback),
+                    type_name::<Rc<U>>()
+                );
+                #[cfg(not(feature = "type_name_of_val"))]
+                panic!("`{:p}` is not a '{}' type", &fallback, type_name::<Rc<U>>());
             }
+            SharedType::<U>::empty()
         }
     }
 }