Fix: unused variable warnings

src/core/pool_type.hpp

@@ -155,7 +155,8 @@ struct Pool : PoolBase {
 			this->ValidateIndex();
 		};
 
-		bool operator!=(const PoolIterator &other) const { return this->index != other.index; }
+		bool operator==(const PoolIterator &other) const { return this->index == other.index; }
+		bool operator!=(const PoolIterator &other) const { return !(*this == other); }
 		T * operator*() const { return T::Get(this->index); }
 		PoolIterator & operator++() { this->index++; this->ValidateIndex(); return *this; }
 
@@ -176,6 +177,7 @@ struct Pool : PoolBase {
 		IterateWrapper(size_t from = 0, std::function<bool(size_t)> filter = nullptr) : from(from), filter(filter) {}
 		PoolIterator<T> begin() { return PoolIterator<T>(this->from, this->filter); }
 		PoolIterator<T> end() { return PoolIterator<T>(T::GetPoolSize()); }
+		bool empty() { return this->begin() == this->end(); }
 	};
 
 	/**

src/network/network.cpp

@@ -99,9 +99,7 @@ extern void StateGameLoop();
  */
 bool HasClients()
 {
-	for (NetworkClientSocket *cs : NetworkClientSocket::Iterate()) return true;
-
-	return false;
+	return !NetworkClientSocket::Iterate().empty();
 }
 
 /**

src/road_cmd.cpp

@@ -182,9 +182,7 @@ RoadType AllocateRoadType(RoadTypeLabel label, RoadTramType rtt)
  */
 bool RoadVehiclesAreBuilt()
 {
-	for (const RoadVehicle *rv : RoadVehicle::Iterate()) return true;
-
-	return false;
+	return !RoadVehicle::Iterate().empty();
 }
 
 /**