events: Don't store data of unknown events in enums

crates/ruma-events-macros/src/event_enum.rs

@@ -71,21 +71,6 @@ fn expand_event_enum(
     let variant_decls = variants.iter().map(|v| v.decl());
     let content: Vec<_> =
         events.iter().map(|event| to_event_path(event, kind, var, ruma_events)).collect();
-    let custom_variant = if var.is_redacted() {
-        quote! {
-            /// A redacted event not defined by the Matrix specification
-            #[doc(hidden)]
-            _Custom(
-                #ruma_events::#event_struct<#ruma_events::custom::RedactedCustomEventContent>,
-            ),
-        }
-    } else {
-        quote! {
-            /// An event not defined by the Matrix specification
-            #[doc(hidden)]
-            _Custom(#ruma_events::#event_struct<#ruma_events::custom::CustomEventContent>),
-        }
-    };
 
     let deserialize_impl = expand_deserialize_impl(kind, var, events, variants, ruma_events);
     let field_accessor_impl = expand_accessor_methods(kind, var, variants, ruma_events);
@@ -102,7 +87,9 @@ fn expand_event_enum(
                 #[doc = #events]
                 #variant_decls(#content),
             )*
-            #custom_variant
+            /// An event not defined by the Matrix specification
+            #[doc(hidden)]
+            _Custom(#ruma_events::#event_struct<#ruma_events::custom::_CustomEventContent>),
         }
 
         #deserialize_impl
@@ -122,7 +109,6 @@ fn expand_deserialize_impl(
     let serde_json = quote! { #ruma_events::exports::serde_json };
 
     let ident = kind.to_event_enum_ident(var);
-    let event_struct = kind.to_event_ident(var);
 
     let variant_attrs = variants.iter().map(|v| {
         let attrs = &v.attrs;
@@ -131,31 +117,6 @@ fn expand_deserialize_impl(
     let self_variants = variants.iter().map(|v| v.ctor(quote! { Self }));
     let content = events.iter().map(|event| to_event_path(event, kind, var, ruma_events));
 
-    let custom_deserialize = if var.is_redacted() {
-        quote! {
-            event => {
-                let event = #serde_json::from_str::<#ruma_events::#event_struct<
-                    #ruma_events::custom::RedactedCustomEventContent,
-                >>(json.get())
-                .map_err(D::Error::custom)?;
-
-                Ok(Self::_Custom(event))
-            },
-        }
-    } else {
-        quote! {
-            event => {
-                let event =
-                    #serde_json::from_str::<
-                        #ruma_events::#event_struct<#ruma_events::custom::CustomEventContent>
-                    >(json.get())
-                    .map_err(D::Error::custom)?;
-
-                Ok(Self::_Custom(event))
-            },
-        }
-    };
-
     quote! {
         impl<'de> #serde::de::Deserialize<'de> for #ident {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
@@ -176,7 +137,10 @@ fn expand_deserialize_impl(
                             Ok(#self_variants(event))
                         },
                     )*
-                    #custom_deserialize
+                    _ => {
+                        let event = #serde_json::from_str(json.get()).map_err(D::Error::custom)?;
+                        Ok(Self::_Custom(event))
+                    },
                 }
             }
         }

crates/ruma-events/src/custom.rs

@@ -97,3 +97,54 @@ impl RedactedEventContent for RedactedCustomEventContent {
 impl RedactedMessageEventContent for RedactedCustomEventContent {}
 
 impl RedactedStateEventContent for RedactedCustomEventContent {}
+
+/// A custom event's type. Used for event enum `_Custom` variants.
+#[doc(hidden)]
+// FIXME: Serialize shouldn't be required here, but it's currently a supertrait of EventContent
+#[derive(Clone, Debug, Serialize)]
+#[allow(clippy::exhaustive_structs)]
+pub struct _CustomEventContent {
+    #[serde(skip)]
+    event_type: Box<str>,
+}
+
+impl RedactContent for _CustomEventContent {
+    type Redacted = Self;
+
+    fn redact(self, _: &RoomVersionId) -> Self {
+        self
+    }
+}
+
+impl EventContent for _CustomEventContent {
+    fn event_type(&self) -> &str {
+        &self.event_type
+    }
+
+    fn from_parts(event_type: &str, _content: &RawJsonValue) -> serde_json::Result<Self> {
+        Ok(Self { event_type: event_type.into() })
+    }
+}
+
+impl RedactedEventContent for _CustomEventContent {
+    fn empty(event_type: &str) -> serde_json::Result<Self> {
+        Ok(Self { event_type: event_type.into() })
+    }
+
+    fn has_serialize_fields(&self) -> bool {
+        false
+    }
+
+    fn has_deserialize_fields() -> HasDeserializeFields {
+        HasDeserializeFields::False
+    }
+}
+
+impl GlobalAccountDataEventContent for _CustomEventContent {}
+impl RoomAccountDataEventContent for _CustomEventContent {}
+impl ToDeviceEventContent for _CustomEventContent {}
+impl EphemeralRoomEventContent for _CustomEventContent {}
+impl MessageEventContent for _CustomEventContent {}
+impl StateEventContent for _CustomEventContent {}
+impl RedactedMessageEventContent for _CustomEventContent {}
+impl RedactedStateEventContent for _CustomEventContent {}

crates/ruma-events/src/lib.rs

@@ -411,10 +411,7 @@ pub struct PrivOwnedStr(Box<str>);
 /// only be created by deserializing from an unknown event type.
 #[doc(hidden)]
 #[allow(clippy::ptr_arg)]
-pub fn serialize_custom_event_error<S: Serializer>(
-    _: &PrivOwnedStr,
-    _: S,
-) -> Result<S::Ok, S::Error> {
+pub fn serialize_custom_event_error<T, S: Serializer>(_: &T, _: S) -> Result<S::Ok, S::Error> {
     Err(serde::ser::Error::custom(
         "Failed to serialize event [content] enum: Unknown event type.\n\
          To send custom events, turn them into `Raw<EnumType>` by going through