Track xml:lang throughout parsing

parsers/src/iq.rs

@@ -229,6 +229,7 @@ impl ::xso::FromXml for Iq {
     fn from_events(
         qname: ::xso::exports::rxml::QName,
         attrs: ::xso::exports::rxml::AttrMap,
+        _ctx: &::xso::Context<'_>,
     ) -> Result<Self::Builder, ::xso::error::FromEventsError> {
         if qname.0 != crate::ns::DEFAULT_NS || qname.1 != "iq" {
             return Err(::xso::error::FromEventsError::Mismatch { name: qname, attrs });

parsers/src/jingle.rs

@@ -203,6 +203,7 @@ impl ::xso::FromXml for Description {
     fn from_events(
         qname: ::xso::exports::rxml::QName,
         attrs: ::xso::exports::rxml::AttrMap,
+        _ctx: &::xso::Context<'_>,
     ) -> Result<Self::Builder, ::xso::error::FromEventsError> {
         if qname.1 != "description" {
             return Err(::xso::error::FromEventsError::Mismatch { name: qname, attrs });
@@ -263,6 +264,7 @@ impl ::xso::FromXml for Transport {
     fn from_events(
         qname: ::xso::exports::rxml::QName,
         attrs: ::xso::exports::rxml::AttrMap,
+        _ctx: &::xso::Context<'_>,
     ) -> Result<Self::Builder, ::xso::error::FromEventsError> {
         if qname.1 != "transport" {
             return Err(::xso::error::FromEventsError::Mismatch { name: qname, attrs });

parsers/src/jingle_s5b.rs

@@ -290,6 +290,7 @@ impl ::xso::FromXml for Transport {
     fn from_events(
         qname: ::xso::exports::rxml::QName,
         attrs: ::xso::exports::rxml::AttrMap,
+        _ctx: &::xso::Context<'_>,
     ) -> Result<Self::Builder, ::xso::error::FromEventsError> {
         if qname.0 != crate::ns::JINGLE_S5B || qname.1 != "transport" {
             return Err(::xso::error::FromEventsError::Mismatch { name: qname, attrs });

parsers/src/util/macro_tests.rs

@@ -2489,3 +2489,65 @@ fn text_vs_attribute_ordering_compile_bug_roundtrip_with_parent() {
         "<thread xmlns='urn:example:ns1' parent='bar'>foo</thread>",
     );
 }
+
+#[derive(FromXml, AsXml, PartialEq, Debug, Clone)]
+#[xml(namespace = NS1, name = "elem")]
+struct Language {
+    #[xml(child(default))]
+    child: core::option::Option<Box<Language>>,
+
+    #[xml(lang)]
+    lang: core::option::Option<String>,
+}
+
+#[test]
+fn language_roundtrip_absent() {
+    #[allow(unused_imports)]
+    use core::{
+        option::Option::{None, Some},
+        result::Result::{Err, Ok},
+    };
+    roundtrip_full::<Language>("<elem xmlns='urn:example:ns1'/>");
+}
+
+#[test]
+fn language_roundtrip_present() {
+    #[allow(unused_imports)]
+    use core::{
+        option::Option::{None, Some},
+        result::Result::{Err, Ok},
+    };
+    roundtrip_full::<Language>("<elem xmlns='urn:example:ns1' xml:lang='foo'/>");
+}
+
+#[test]
+fn language_roundtrip_nested_parse() {
+    // cannot write a round-trip test for this, because on emission,
+    // `#[xml(language)]` fields with a non-None value will always emit
+    // the `xml:lang` attribute to ensure semantic correctness.
+    #[allow(unused_imports)]
+    use core::{
+        option::Option::{None, Some},
+        result::Result::{Err, Ok},
+    };
+    match parse_str::<Language>(
+        "<elem xmlns='urn:example:ns1' xml:lang='foo'><elem><elem xml:lang='bar'/></elem></elem>",
+    ) {
+        Ok(Language { child, lang }) => {
+            assert_eq!(lang.as_deref(), Some("foo"));
+
+            let Some(Language { child, lang }) = child.map(|x| *x) else {
+                panic!("missing child");
+            };
+            assert_eq!(lang.as_deref(), Some("foo"));
+
+            let Some(Language { child, lang }) = child.map(|x| *x) else {
+                panic!("missing grand child");
+            };
+            assert_eq!(lang.as_deref(), Some("bar"));
+
+            assert!(child.is_none());
+        }
+        other => panic!("unexpected parse result: {:?}", other),
+    }
+}

parsers/src/util/macros.rs

@@ -262,6 +262,7 @@ macro_rules! generate_attribute_enum {
             fn from_events(
                 qname: ::xso::exports::rxml::QName,
                 attrs: ::xso::exports::rxml::AttrMap,
+                _ctx: &::xso::Context<'_>,
             ) -> Result<Self::Builder, ::xso::error::FromEventsError> {
                 if qname.0 != crate::ns::$ns || qname.1 != $name {
                     return Err(::xso::error::FromEventsError::Mismatch {