sync: always include_redundant_members when using element_hacks feature

see:
- matrix-org/matrix-js-sdk#4329
- https://github.com/element-hq/synapse/blob/568051c0f07393b786b9d813a1db53dd332c9fc2/synapse/handlers/pagination.py#L639
- https://matrix.to/#/!n8DKU1BeeJilOJXDPr:seirdy.one/$gvGF7GuPrLPR8nHg4UiHvP-ZVwuiMkYS8O6VlsDCW9w?via=awawawawawawawawawawawawawawawawawawawawawawawawawawawawawawaw.gay&via=transfem.dev&via=matrix.org

Signed-off-by: strawberry <[email protected]>

src/api/client/context.rs

@@ -21,11 +21,13 @@ pub(crate) async fn get_context_route(
 	let sender_user = body.sender_user.as_ref().expect("user is authenticated");
 	let sender_device = body.sender_device.as_ref().expect("user is authenticated");
 
+	// some clients, at least element, seem to require knowledge of redundant
+	// members for "inline" profiles on the timeline to work properly
 	let (lazy_load_enabled, lazy_load_send_redundant) = match &body.filter.lazy_load_options {
 		LazyLoadOptions::Enabled {
 			include_redundant_members,
 		} => (true, *include_redundant_members),
-		LazyLoadOptions::Disabled => (false, false),
+		LazyLoadOptions::Disabled => (false, cfg!(feature = "element_hacks")),
 	};
 
 	let mut lazy_loaded = HashSet::new();

src/api/client/sync.rs

@@ -106,11 +106,13 @@ pub(crate) async fn sync_events_route(
 			.unwrap_or_default(),
 	};
 
+	// some clients, at least element, seem to require knowledge of redundant
+	// members for "inline" profiles on the timeline to work properly
 	let (lazy_load_enabled, lazy_load_send_redundant) = match filter.room.state.lazy_load_options {
 		LazyLoadOptions::Enabled {
-			include_redundant_members: redundant,
-		} => (true, redundant),
-		LazyLoadOptions::Disabled => (false, false),
+			include_redundant_members,
+		} => (true, include_redundant_members),
+		LazyLoadOptions::Disabled => (false, cfg!(feature = "element_hacks")),
 	};
 
 	let full_state = body.full_state;