Fix PhysicalExpr hash (#381)

Author: joroKr21

datafusion/physical-expr-common/src/physical_expr.rs

@@ -185,6 +185,7 @@ pub trait PhysicalExpr: Send + Sync + Display + Debug + PartialEq<dyn Any> {
 
 impl Hash for dyn PhysicalExpr {
     fn hash<H: Hasher>(&self, state: &mut H) {
+        self.as_any().type_id().hash(state);
         self.dyn_hash(state);
     }
 }

datafusion/physical-expr/src/scalar_function.rs

@@ -199,7 +199,7 @@ impl PhysicalExpr for ScalarFunctionExpr {
         self.name.hash(&mut s);
         self.args.hash(&mut s);
         self.return_type.hash(&mut s);
-        // Add `self.fun` when hash is available
+        self.fun.hash(&mut s)
     }
 
     fn get_properties(&self, children: &[ExprProperties]) -> Result<ExprProperties> {