xso-proc: Allow #[xml(flag)] without params

The namespace defaults to the parent’s namespace, and the name to the
field name, so we can avoid needlessly duplicating that info.

parsers/src/sm.rs

@@ -139,7 +139,7 @@ pub struct Resumed {
 #[xml(namespace = ns::SM, name = "sm")]
 pub struct StreamManagement {
     /// `<optional/>` flag.
-    #[xml(flag(name = "optional"))]
+    #[xml(flag)]
     pub optional: bool,
 }
 

parsers/src/starttls.rs

@@ -25,7 +25,7 @@ pub struct Proceed;
 #[xml(namespace = ns::TLS, name = "starttls")]
 pub struct StartTls {
     /// Marker for mandatory StartTLS.
-    #[xml(flag(name = "required"))]
+    #[xml(flag)]
     pub required: bool,
 }
 

parsers/src/util/macro_tests.rs

@@ -1977,7 +1977,7 @@ fn extract_ignore_unknown_stuff_roundtrip() {
 #[derive(FromXml, AsXml, PartialEq, Debug, Clone)]
 #[xml(namespace = NS1, name = "foo")]
 struct Flag {
-    #[xml(flag(namespace = NS1, name = "flag"))]
+    #[xml(flag)]
     flag: bool,
 }