serialize tuple struct in the same way as sequence

Author: sigmaris

src/ser/mod.rs

@@ -178,7 +178,7 @@ impl<'a, 'b: 'a> ser::Serializer for &'a mut Serializer<'b> {
     type Error = Error;
     type SerializeSeq = SerializeSeq<'a, 'b>;
     type SerializeTuple = SerializeSeq<'a, 'b>;
-    type SerializeTupleStruct = Unreachable;
+    type SerializeTupleStruct = SerializeSeq<'a, 'b>;
     type SerializeTupleVariant = Unreachable;
     type SerializeMap = SerializeMap<'a, 'b>;
     type SerializeStruct = SerializeStruct<'a, 'b>;
@@ -385,9 +385,9 @@ impl<'a, 'b: 'a> ser::Serializer for &'a mut Serializer<'b> {
     fn serialize_tuple_struct(
         self,
         _name: &'static str,
-        _len: usize,
+        len: usize,
     ) -> Result<Self::SerializeTupleStruct> {
-        unreachable!()
+        self.serialize_seq(Some(len))
     }
 
     fn serialize_tuple_variant(
@@ -822,6 +822,19 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_tuple_struct() {
+        #[derive(Serialize)]
+        struct A<'a>(u32, Option<&'a str>, u16, bool);
+
+        let a = A(42, Some("A string"), 720, false);
+
+        assert_eq!(
+            &*crate::to_string::<_, N>(&a).unwrap(),
+            r#"[42,"A string",720,false]"#
+        );
+    }
+
     #[test]
     fn test_serialize_bytes() {
         use core::fmt::Write;

src/ser/seq.rs

@@ -51,3 +51,19 @@ impl<'a, 'b: 'a> ser::SerializeTuple for SerializeSeq<'a, 'b> {
         ser::SerializeSeq::end(self)
     }
 }
+
+impl<'a, 'b: 'a> ser::SerializeTupleStruct for SerializeSeq<'a, 'b> {
+    type Ok = ();
+    type Error = Error;
+
+    fn serialize_field<T: ?Sized>(&mut self, value: &T) -> Result<()>
+    where
+        T: ser::Serialize,
+    {
+        ser::SerializeSeq::serialize_element(self, value)
+    }
+
+    fn end(self) -> Result<Self::Ok> {
+        ser::SerializeSeq::end(self)
+    }
+}