Use WindowUDFImpl::downcast_ref and is() instead of as &dyn Any patterns

Replaces `(udwf.inner().as_ref() as &dyn Any).downcast_ref::<T>()` and
`.is::<T>()` call sites with the new inherent methods on
`dyn WindowUDFImpl`. Removes now-unused `std::any::Any` imports.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: timsaucer

datafusion/ffi/src/proto/logical_extension_codec.rs

@@ -489,7 +489,6 @@ impl LogicalExtensionCodec for ForeignLogicalExtensionCodec {
 
 #[cfg(test)]
 mod tests {
-    use std::any::Any;
     use std::sync::Arc;
 
     use arrow::array::record_batch;
@@ -704,7 +703,7 @@ mod tests {
 
         let returned_udf = foreign_codec.try_decode_udwf(udf.name(), &bytes)?;
 
-        assert!((returned_udf.inner().as_ref() as &dyn Any).is::<Rank>());
+        assert!(returned_udf.inner().is::<Rank>());
 
         Ok(())
     }

datafusion/ffi/src/proto/physical_extension_codec.rs

@@ -410,7 +410,6 @@ impl PhysicalExtensionCodec for ForeignPhysicalExtensionCodec {
 
 #[cfg(test)]
 pub(crate) mod tests {
-    use std::any::Any;
     use std::sync::Arc;
 
     use arrow_schema::{DataType, Field, Schema};
@@ -550,7 +549,7 @@ pub(crate) mod tests {
             buf.push(Self::MAGIC_NUMBER);
 
             let udf = node.inner();
-            let Some(udf) = (udf.as_ref() as &dyn Any).downcast_ref::<Rank>() else {
+            let Some(udf) = udf.downcast_ref::<Rank>() else {
                 return exec_err!("TestExtensionCodec only expects Rank UDWF");
             };
 
@@ -654,7 +653,7 @@ pub(crate) mod tests {
 
         let returned_udf = foreign_codec.try_decode_udwf(udf.name(), &bytes)?;
 
-        assert!((returned_udf.inner().as_ref() as &dyn Any).is::<Rank>());
+        assert!(returned_udf.inner().is::<Rank>());
 
         Ok(())
     }

datafusion/ffi/src/udwf/mod.rs

@@ -222,9 +222,7 @@ impl Clone for FFI_WindowUDF {
 
 impl From<Arc<WindowUDF>> for FFI_WindowUDF {
     fn from(udf: Arc<WindowUDF>) -> Self {
-        if let Some(udwf) = (udf.inner().as_ref() as &dyn std::any::Any)
-            .downcast_ref::<ForeignWindowUDF>()
-        {
+        if let Some(udwf) = udf.inner().downcast_ref::<ForeignWindowUDF>() {
             return udwf.udf.clone();
         }
 
@@ -474,20 +472,12 @@ mod tests {
 
         // Verify local libraries can be downcast to their original
         let foreign_udwf: Arc<dyn WindowUDFImpl> = (&ffi_udwf).into();
-        assert!(
-            (foreign_udwf.as_ref() as &dyn std::any::Any)
-                .downcast_ref::<WindowShift>()
-                .is_some()
-        );
+        assert!(foreign_udwf.is::<WindowShift>());
 
         // Verify different library markers generate foreign providers
         ffi_udwf.library_marker_id = crate::mock_foreign_marker_id;
         let foreign_udwf: Arc<dyn WindowUDFImpl> = (&ffi_udwf).into();
-        assert!(
-            (foreign_udwf.as_ref() as &dyn std::any::Any)
-                .downcast_ref::<ForeignWindowUDF>()
-                .is_some()
-        );
+        assert!(foreign_udwf.is::<ForeignWindowUDF>());
 
         Ok(())
     }

datafusion/proto/tests/cases/roundtrip_physical_plan.rs

@@ -1333,7 +1333,7 @@ impl PhysicalExtensionCodec for UDFExtensionCodec {
 
     fn try_encode_udwf(&self, node: &WindowUDF, buf: &mut Vec<u8>) -> Result<()> {
         let binding = node.inner();
-        if let Some(udwf) = (binding.as_ref() as &dyn Any).downcast_ref::<CustomUDWF>() {
+        if let Some(udwf) = binding.downcast_ref::<CustomUDWF>() {
             let proto = CustomUDWFNode {
                 payload: udwf.payload.clone(),
             };