parsers: port version to derive macros

We can *finally* do it!

parsers/src/version.rs

@@ -19,23 +19,25 @@ pub struct VersionQuery;
 
 impl IqGetPayload for VersionQuery {}
 
-generate_element!(
 /// Represents the answer about the software version we are using.
 ///
 /// It should only be used in an `<iq type='result'/>`, as it can only
 /// represent the result, and not a request.
-    VersionResult, "query", VERSION,
+#[derive(FromXml, AsXml, PartialEq, Debug, Clone)]
-    children: [
+#[xml(namespace = ns::VERSION, name = "query")]
+pub struct VersionResult {
     /// The name of this client.
-        name: Required<String> = ("name", VERSION) => String,
+    #[xml(extract(fields(text)))]
+    pub name: String,
 
     /// The version of this client.
-        version: Required<String> = ("version", VERSION) => String,
+    #[xml(extract(fields(text)))]
+    pub version: String,
 
     /// The OS this client is running on.
-        os: Option<String> = ("os", VERSION) => String
+    #[xml(extract(default, fields(text(type_ = String))))]
-    ]
+    pub os: Option<String>,
-);
+}
 
 impl IqResultPayload for VersionResult {}