refactor: improve code based on clippy

yaserde_derive/src/common/field.rs

@@ -175,6 +175,7 @@ impl YaSerdeField {
 }
 
 #[derive(Debug)]
+#[allow(clippy::enum_variant_names)]
 pub enum Field {
   FieldString,
   FieldBool,

yaserde_derive/src/de/expand_struct.rs

@@ -199,17 +199,17 @@ pub fn parse(
     .iter()
     .map(|field| YaSerdeField::new(field.clone()))
     .filter(|field| !field.is_attribute() && field.is_flatten())
-    .filter_map(|field| {
+    .map(|field| {
       let value_label = field.get_value_label();
 
       match field.get_type() {
-        Field::FieldStruct { .. } => Some(quote! {
+        Field::FieldStruct { .. } => quote! {
           #value_label = ::yaserde::de::from_str(&unused_xml_elements)?;
-        }),
+        },
         Field::FieldOption { data_type } => match *data_type {
-          Field::FieldStruct { .. } => Some(quote! {
+          Field::FieldStruct { .. } => quote! {
             #value_label = ::yaserde::de::from_str(&unused_xml_elements).ok();
-          }),
+          },
           field_type => unimplemented!(r#""flatten" is not implemented for {:?}"#, field_type),
         },
         field_type => unimplemented!(r#""flatten" is not implemented for {:?}"#, field_type),

yaserde_derive/src/ser/expand_enum.rs

@@ -33,7 +33,6 @@ pub fn serialize(
 
       let attribute_fields: Vec<_> = all_fields
         .clone()
-        .into_iter()
         .filter(|field| {
           field.is_attribute()
             || (field.is_flatten() && matches!(field.get_type(), Field::FieldStruct { .. }))