Fix test for #580 which was incorrect and fix the deserializer fix for it

Author: Mingun

src/de/map.rs

@@ -883,17 +883,16 @@ where
     }
 
     /// Forwards deserialization of the inner type. Always calls [`Visitor::visit_newtype_struct`]
-    /// with the [`SimpleTypeDeserializer`].
+    /// with this deserializer.
     fn deserialize_newtype_struct<V>(
-        mut self,
+        self,
         _name: &'static str,
         visitor: V,
     ) -> Result<V::Value, Self::Error>
     where
         V: Visitor<'de>,
     {
-        let text = self.read_string()?;
-        visitor.visit_newtype_struct(SimpleTypeDeserializer::from_text(text))
+        visitor.visit_newtype_struct(self)
     }
 
     /// This method deserializes a sequence inside of element that itself is a

tests/serde-issues.rs

@@ -5,7 +5,8 @@
 use pretty_assertions::assert_eq;
 use quick_xml::de::from_str;
 use quick_xml::se::{to_string, to_string_with_root};
-use serde::{Deserialize, Deserializer, Serialize};
+use serde::de::{Deserializer, IgnoredAny};
+use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 
 /// Regression tests for https://github.com/tafia/quick-xml/issues/252.
@@ -393,10 +394,13 @@ fn issue580() {
     #[derive(Debug, PartialEq, Eq)]
     struct Item;
     impl Item {
-        fn parse<'de, D>(_deserializer: D) -> Result<Self, D::Error>
+        fn parse<'de, D>(deserializer: D) -> Result<Self, D::Error>
         where
             D: Deserializer<'de>,
         {
+            // We should consume something from the deserializer, otherwise this
+            // leads to infinity loop
+            IgnoredAny::deserialize(deserializer)?;
             Ok(Item)
         }
     }