simplify some pattern matches to appease 1.68 clippy (#13833)

substrate/frame/election-provider-multi-phase/src/lib.rs

@@ -502,10 +502,10 @@ where
 	fn eq(&self, other: &Self) -> bool {
 		use ElectionError::*;
 		match (self, other) {
-			(&Feasibility(ref x), &Feasibility(ref y)) if x == y => true,
-			(&Miner(ref x), &Miner(ref y)) if x == y => true,
-			(&DataProvider(ref x), &DataProvider(ref y)) if x == y => true,
-			(&Fallback(ref x), &Fallback(ref y)) if x == y => true,
+			(Feasibility(x), Feasibility(y)) if x == y => true,
+			(Miner(x), Miner(y)) if x == y => true,
+			(DataProvider(x), DataProvider(y)) if x == y => true,
+			(Fallback(x), Fallback(y)) if x == y => true,
 			_ => false,
 		}
 	}

substrate/frame/offences/src/lib.rs

@@ -247,7 +247,7 @@ impl<T: Config, O: Offence<T::IdentificationTuple>> ReportIndexStorage<T, O> {
 	fn insert(&mut self, time_slot: &O::TimeSlot, report_id: ReportIdOf<T>) {
 		// Insert the report id into the list while maintaining the ordering by the time
 		// slot.
-		let pos = self.same_kind_reports.partition_point(|&(ref when, _)| when <= time_slot);
+		let pos = self.same_kind_reports.partition_point(|(when, _)| when <= time_slot);
 		self.same_kind_reports.insert(pos, (time_slot.clone(), report_id));
 
 		// Update the list of concurrent reports.

substrate/frame/session/src/lib.rs

@@ -678,7 +678,7 @@ impl<T: Config> Pallet<T> {
 				// since a new validator set always leads to `changed` starting
 				// as true, we can ensure that `now_session_keys` and `next_validators`
 				// have the same length. this function is called once per iteration.
-				if let Some(&(_, ref old_keys)) = now_session_keys.next() {
+				if let Some((_, old_keys)) = now_session_keys.next() {
 					if old_keys != keys {
 						changed = true;
 					}

substrate/frame/staking/src/pallet/impls.rs

@@ -1299,8 +1299,8 @@ where
 			add_db_reads_writes(1, 0);
 
 			// Reverse because it's more likely to find reports from recent eras.
-			match eras.iter().rev().find(|&&(_, ref sesh)| sesh <= &slash_session) {
-				Some(&(ref slash_era, _)) => *slash_era,
+			match eras.iter().rev().find(|&(_, sesh)| sesh <= &slash_session) {
+				Some((slash_era, _)) => *slash_era,
 				// Before bonding period. defensive - should be filtered out.
 				None => return consumed_weight,
 			}