xmpp-parsers: Remove Feature from disco#info

This was just a newtype for a String, but in general using it was harder
than without it.  This simplifies the public API.

parsers/ChangeLog

@@ -12,6 +12,8 @@ XXXX-YY-ZZ RELEASER <admin@example.com>
           used in XMPP.
         - Remove the unnecessary SaslMechanisms struct, to directly extract
           SASL mechanisms in a Vec<String> in StreamFeatures.
+        - The type of disco::DiscoInfoResult::features changed from
+          Vec<Feature> to Vec<String>, this lets us remove Feature as well.
         - bind::BindFeature::required is now a bool, thanks to xso’s flag.
         - jingle_rtp::Description::rtcp_mux is now a bool flag too.
         - stream_limits::Limits now extract directly to NonZeroU32.

parsers/src/caps.rs

@@ -7,7 +7,7 @@
 use xso::{AsXml, FromXml};
 
 use crate::data_forms::DataForm;
-use crate::disco::{DiscoInfoQuery, DiscoInfoResult, Feature, Identity};
+use crate::disco::{DiscoInfoQuery, DiscoInfoResult, Identity};
 use crate::hashes::{Algo, Hash};
 use crate::ns;
 use crate::presence::PresencePayload;
@@ -79,8 +79,8 @@ fn compute_items<T, F: Fn(&T) -> Vec<u8>>(things: &[T], encode: F) -> Vec<u8> {
     string
 }
 
-fn compute_features(features: &[Feature]) -> Vec<u8> {
-    compute_items(features, |feature| compute_item(&feature.var))
+fn compute_features(features: &[String]) -> Vec<u8> {
+    compute_items(features, |feature| compute_item(&feature))
 }
 
 fn compute_identities(identities: &[Identity]) -> Vec<u8> {

parsers/src/disco.rs

@@ -26,22 +26,6 @@ pub struct DiscoInfoQuery {
 
 impl IqGetPayload for DiscoInfoQuery {}
 
-/// Structure representing a `<feature xmlns='http://jabber.org/protocol/disco#info'/>` element.
-#[derive(FromXml, AsXml, Debug, Clone, PartialEq, Eq, Hash)]
-#[xml(namespace = ns::DISCO_INFO, name = "feature")]
-pub struct Feature {
-    /// Namespace of the feature we want to represent.
-    #[xml(attribute)]
-    pub var: String,
-}
-
-impl Feature {
-    /// Create a new `<feature/>` with the according `@var`.
-    pub fn new<S: Into<String>>(var: S) -> Feature {
-        Feature { var: var.into() }
-    }
-}
-
 /// Structure representing an `<identity xmlns='http://jabber.org/protocol/disco#info'/>` element.
 #[derive(FromXml, AsXml, Debug, Clone, PartialEq, Eq, Hash)]
 #[xml(namespace = ns::DISCO_INFO, name = "identity")]
@@ -113,8 +97,8 @@ pub struct DiscoInfoResult {
     pub identities: Vec<Identity>,
 
     /// List of features supported by this entity.
-    #[xml(child(n = ..))]
-    pub features: Vec<Feature>,
+    #[xml(extract(n = .., name = "feature", fields(attribute(name = "var", type_ = String))))]
+    pub features: Vec<String>,
 
     /// List of extensions reported by this entity.
     #[xml(child(n = ..))]
@@ -192,7 +176,6 @@ mod tests {
     #[test]
     fn test_size() {
         assert_size!(Identity, 48);
-        assert_size!(Feature, 12);
         assert_size!(DiscoInfoQuery, 12);
         assert_size!(DiscoInfoResult, 48);
 
@@ -205,7 +188,6 @@ mod tests {
     #[test]
     fn test_size() {
         assert_size!(Identity, 96);
-        assert_size!(Feature, 24);
         assert_size!(DiscoInfoQuery, 24);
         assert_size!(DiscoInfoResult, 96);
 
@@ -325,9 +307,11 @@ mod tests {
             FromElementError::Invalid(Error::Other(string)) => string,
             _ => panic!(),
         };
+        // TODO: Make xso generate a better error message, with s/unnamed field 0/'var'/ for
+        // instance.
         assert_eq!(
             message,
-            "Required attribute field 'var' on Feature element missing."
+            "Required attribute unnamed field 0 on extraction for field 'features' in DiscoInfoResult element missing."
         );
     }
 

parsers/src/ecaps2.rs

@@ -7,7 +7,7 @@
 use xso::{AsXml, FromXml};
 
 use crate::data_forms::DataForm;
-use crate::disco::{DiscoInfoQuery, DiscoInfoResult, Feature, Identity};
+use crate::disco::{DiscoInfoQuery, DiscoInfoResult, Identity};
 use crate::hashes::{Algo, Hash};
 use crate::ns;
 use crate::presence::PresencePayload;
@@ -64,8 +64,8 @@ fn compute_items<'x, T: 'x, I: IntoIterator<Item = &'x T>, F: Fn(&'x T) -> Vec<u
     string
 }
 
-fn compute_features(features: &[Feature]) -> Vec<u8> {
-    compute_items(features, 0x1c, |feature| compute_item(&feature.var))
+fn compute_features(features: &[String]) -> Vec<u8> {
+    compute_items(features, 0x1c, |feature| compute_item(&feature))
 }
 
 fn compute_identities(identities: &[Identity]) -> Vec<u8> {