Pair serialize_with and deserialize_with into one attribute

test_suite/tests/test_gen.rs

@@ -30,6 +30,14 @@ fn test_gen() {
     }
     assert::<With<i32>>();
 
+    #[derive(Serialize, Deserialize)]
+    struct WithTogether<T> {
+        t: T,
+        #[serde(with="both_x")]
+        x: X,
+    }
+    assert::<WithTogether<i32>>();
+
     #[derive(Serialize, Deserialize)]
     struct WithRef<'a, T: 'a> {
         #[serde(skip_deserializing)]
@@ -307,16 +315,20 @@ trait DeserializeWith: Sized {
 }
 
 // Implements neither Serialize nor Deserialize
-struct X;
+pub struct X;
 
-fn ser_x<S: Serializer>(_: &X, _: S) -> StdResult<S::Ok, S::Error> {
+pub fn ser_x<S: Serializer>(_: &X, _: S) -> StdResult<S::Ok, S::Error> {
     unimplemented!()
 }
 
-fn de_x<D: Deserializer>(_: D) -> StdResult<X, D::Error> {
+pub fn de_x<D: Deserializer>(_: D) -> StdResult<X, D::Error> {
     unimplemented!()
 }
 
+mod both_x {
+    pub use super::{ser_x as serialize, de_x as deserialize};
+}
+
 impl SerializeWith for X {
     fn serialize_with<S: Serializer>(_: &Self, _: S) -> StdResult<S::Ok, S::Error> {
         unimplemented!()