Fix datediff array length mismatch for dictionary-backed timestamps

Author: vigneshsiva11

native/spark-expr/src/datetime_funcs/date_diff.rs

@@ -16,6 +16,7 @@
 // under the License.
 
 use arrow::array::{Array, Date32Array, Int32Array};
+use arrow::compute::cast;
 use arrow::compute::kernels::arity::binary;
 use arrow::datatypes::DataType;
 use datafusion::common::{utils::take_function_args, DataFusionError, Result};
@@ -84,6 +85,12 @@ impl ScalarUDFImpl for SparkDateDiff {
         let end_arr = end_date.into_array(num_rows)?;
         let start_arr = start_date.into_array(num_rows)?;
 
+        // Normalize dictionary arrays (important for Iceberg)
+        let end_arr = cast(&end_arr, &DataType::Date32)
+            .map_err(|e| DataFusionError::Execution(e.to_string()))?;
+        let start_arr = cast(&start_arr, &DataType::Date32)
+            .map_err(|e| DataFusionError::Execution(e.to_string()))?;
+
         let end_date_array = end_arr
             .as_any()
             .downcast_ref::<Date32Array>()
@@ -106,8 +113,4 @@ impl ScalarUDFImpl for SparkDateDiff {
 
         Ok(ColumnarValue::Array(Arc::new(result)))
     }
-
-    fn aliases(&self) -> &[String] {
-        &self.aliases
-    }
 }