Correctly deserialize newtype struct (#168)

src/serde/de.rs

@@ -320,10 +320,17 @@ impl<'lua, 'de> serde::Deserializer<'de> for Deserializer<'lua> {
         self.deserialize_map(visitor)
     }
 
+    #[inline]
+    fn deserialize_newtype_struct<V>(self, _name: &'static str, visitor: V) -> Result<V::Value>
+    where
+        V: de::Visitor<'de>,
+    {
+        visitor.visit_newtype_struct(self)
+    }
+
     serde::forward_to_deserialize_any! {
         bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string bytes
-        byte_buf unit unit_struct newtype_struct
-        identifier ignored_any
+        byte_buf unit unit_struct identifier ignored_any
     }
 }
 

tests/serde.rs

@@ -375,6 +375,19 @@ fn test_from_value_struct() -> Result<(), Box<dyn std::error::Error>> {
     Ok(())
 }
 
+#[test]
+fn test_from_value_newtype_struct() -> Result<(), Box<dyn std::error::Error>> {
+    let lua = Lua::new();
+
+    #[derive(Deserialize, PartialEq, Debug)]
+    struct Test(f64);
+
+    let got = lua.from_value(Value::Number(123.456))?;
+    assert_eq!(Test(123.456), got);
+
+    Ok(())
+}
+
 #[test]
 fn test_from_value_enum() -> Result<(), Box<dyn std::error::Error>> {
     let lua = Lua::new();