util/StringWithHash: add std::hash specialization

src/stock/MapStock.hxx

@@ -40,18 +40,6 @@ class StockMap {
 		void OnDeferredEmpty() noexcept;
 
 	public:
-		struct Hash {
-			constexpr size_t operator()(const StockKey &key) const noexcept {
-				return key.hash;
-			}
-		};
-
-		struct Equal {
-			constexpr bool operator()(const StockKey &a, const StockKey &b) const noexcept {
-				return a == b;
-			}
-		};
-
 		struct GetKeyFunction {
 			[[gnu::pure]]
 			StockKey operator()(const Item &item) const noexcept {
@@ -65,8 +53,8 @@ class StockMap {
 		IntrusiveHashSet<Item, N_BUCKETS,
 				 IntrusiveHashSetOperators<Item,
 							   Item::GetKeyFunction,
-							   Item::Hash,
-							   Item::Equal>>;
+							   std::hash<StockKey>,
+							   std::equal_to<StockKey>>>;
 
 	EventLoop &event_loop;
 

src/stock/MultiStock.hxx

@@ -307,18 +307,6 @@ class MultiStock {
 				     std::exception_ptr ep) noexcept override;
 
 	public:
-		struct Hash {
-			constexpr size_t operator()(const StockKey &key) const noexcept {
-				return key.hash;
-			}
-		};
-
-		struct Equal {
-			constexpr bool operator()(const StockKey &a, const StockKey &b) const noexcept {
-				return a == b;
-			}
-		};
-
 		struct GetKey {
 			[[gnu::pure]]
 			StockKey operator()(const MapItem &item) const noexcept {
@@ -342,8 +330,8 @@ class MultiStock {
 	using Map =
 		IntrusiveHashSet<MapItem, N_BUCKETS,
 				 IntrusiveHashSetOperators<MapItem, MapItem::GetKey,
-							   MapItem::Hash,
-							   MapItem::Equal>>;
+							   std::hash<StockKey>,
+							   std::equal_to<StockKey>>>;
 
 	Map map;
 

src/util/StringWithHash.hxx

@@ -28,3 +28,10 @@ struct StringWithHash {
 
 	constexpr bool operator==(const StringWithHash &) const noexcept = default;
 };
+
+template<>
+struct std::hash<StringWithHash> {
+	constexpr std::size_t operator()(const StringWithHash &s) const noexcept {
+		return s.hash;
+	}
+};