introduce a type to refer to a torrent-list-index, to improve type safety

include/libtorrent/aux_/session_impl.hpp

@@ -300,10 +300,10 @@ namespace aux {
 			io_service& get_io_service() override { return m_io_service; }
 			resolver_interface& get_resolver() override { return m_host_resolver; }
 
-			aux::vector<torrent*>& torrent_list(int i) override
+			aux::vector<torrent*>& torrent_list(torrent_list_index_t i) override
 			{
-				TORRENT_ASSERT(i >= 0);
+				TORRENT_ASSERT(i >= torrent_list_index_t{});
-				TORRENT_ASSERT(i < session_interface::num_torrent_lists);
+				TORRENT_ASSERT(i < m_torrent_lists.end_index());
 				return m_torrent_lists[i];
 			}
 
@@ -739,7 +739,8 @@ namespace aux {
 			// negative, return INT_MAX
 			int get_int_setting(int n) const;
 
-			aux::vector<torrent*> m_torrent_lists[num_torrent_lists];
+			aux::array<aux::vector<torrent*>, num_torrent_lists, torrent_list_index_t>
+				m_torrent_lists;
 
 			peer_class_pool m_classes;
 

include/libtorrent/aux_/session_interface.hpp

@@ -45,6 +45,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/aux_/listen_socket_handle.hpp"
 #include "libtorrent/session_types.hpp"
 #include "libtorrent/flags.hpp"
+#include "libtorrent/link.hpp" // for torrent_list_index_t
 
 #include <functional>
 #include <memory>
@@ -252,41 +253,35 @@ namespace libtorrent { namespace aux {
 		virtual void sent_syn(bool ipv6) = 0;
 		virtual void received_synack(bool ipv6) = 0;
 
-		enum torrent_list_index
+		// this is the set of (subscribed) torrents that have changed
-		{
+		// their states since the last time the user requested updates.
-			// this is the set of (subscribed) torrents that have changed
+		static constexpr torrent_list_index_t torrent_state_updates{0};
-			// their states since the last time the user requested updates.
-			torrent_state_updates,
 
 			// all torrents that want to be ticked every second
-			torrent_want_tick,
+		static constexpr torrent_list_index_t torrent_want_tick{1};
 
 			// all torrents that want more peers and are still downloading
 			// these typically have higher priority when connecting peers
-			torrent_want_peers_download,
+		static constexpr torrent_list_index_t torrent_want_peers_download{2};
 
 			// all torrents that want more peers and are finished downloading
-			torrent_want_peers_finished,
+		static constexpr torrent_list_index_t torrent_want_peers_finished{3};
 
 			// torrents that want auto-scrape (only paused auto-managed ones)
-			torrent_want_scrape,
+		static constexpr torrent_list_index_t torrent_want_scrape{4};
 
 			// auto-managed torrents by state. Only these torrents are considered
 			// when recalculating auto-managed torrents. started auto managed
 			// torrents that are inactive are not part of these lists, because they
 			// are not considered for auto managing (they are left started
 			// unconditionally)
-			torrent_downloading_auto_managed,
+		static constexpr torrent_list_index_t torrent_downloading_auto_managed{5};
-			torrent_seeding_auto_managed,
+		static constexpr torrent_list_index_t torrent_seeding_auto_managed{6};
-			torrent_checking_auto_managed,
+		static constexpr torrent_list_index_t torrent_checking_auto_managed{7};
 
-			// all torrents that have resume data to save
+		static constexpr std::size_t num_torrent_lists = 8;
-//			torrent_want_save_resume,
 
-			num_torrent_lists
+		virtual aux::vector<torrent*>& torrent_list(torrent_list_index_t i) = 0;
-		};
-
-		virtual aux::vector<torrent*>& torrent_list(int i) = 0;
 
 		virtual bool has_lsd() const = 0;
 		virtual void announce_lsd(sha1_hash const& ih, int port, bool broadcast = false) = 0;

include/libtorrent/link.hpp

@@ -34,9 +34,13 @@ POSSIBILITY OF SUCH DAMAGE.
 #define TORRENT_LINK_HPP_INCLUDED
 
 #include "libtorrent/aux_/vector.hpp"
+#include "libtorrent/units.hpp"
 
 namespace libtorrent {
 
+	struct torrent_list_tag;
+	using torrent_list_index_t = aux::strong_typedef<int, torrent_list_tag>;
+
 	struct link
 	{
 		link() : index(-1) {}
@@ -50,7 +54,8 @@ namespace libtorrent {
 		void clear() { index = -1; }
 
 		template <class T>
-		void unlink(aux::vector<T*>& list, int link_index)
+		void unlink(aux::vector<T*>& list
+			, torrent_list_index_t const link_index)
 		{
 			if (index == -1) return;
 			TORRENT_ASSERT(index >= 0 && index < int(list.size()));

include/libtorrent/torrent.hpp

@@ -1164,7 +1164,7 @@ namespace libtorrent {
 		torrent_state get_peer_list_state();
 
 		void construct_storage();
-		void update_list(int list, bool in);
+		void update_list(torrent_list_index_t list, bool in);
 
 		void on_files_deleted(storage_error const& error);
 		void on_torrent_paused();
@@ -1366,7 +1366,8 @@ namespace libtorrent {
 
 		// TODO: 3 factor out the links (as well as update_list() to a separate
 		// class that torrent can inherit)
-		link m_links[aux::session_interface::num_torrent_lists];
+		aux::array<link, aux::session_interface::num_torrent_lists, torrent_list_index_t>
+			m_links;
 
 	private:
 

src/session.cpp

@@ -50,6 +50,17 @@ namespace libtorrent {
 	constexpr feature_flags_t plugin::alert_feature;
 #endif
 
+namespace aux {
+	constexpr torrent_list_index_t session_interface::torrent_state_updates;
+	constexpr torrent_list_index_t session_interface::torrent_want_tick;
+	constexpr torrent_list_index_t session_interface::torrent_want_peers_download;
+	constexpr torrent_list_index_t session_interface::torrent_want_peers_finished;
+	constexpr torrent_list_index_t session_interface::torrent_want_scrape;
+	constexpr torrent_list_index_t session_interface::torrent_downloading_auto_managed;
+	constexpr torrent_list_index_t session_interface::torrent_seeding_auto_managed;
+	constexpr torrent_list_index_t session_interface::torrent_checking_auto_managed;
+}
+
 	settings_pack min_memory_usage()
 	{
 		settings_pack set;

src/session_impl.cpp

@@ -6817,7 +6817,7 @@ namespace {
 			&& m_settings.get_int(settings_pack::choking_algorithm) == settings_pack::fixed_slots_choker)
 			TORRENT_ASSERT(m_stats_counters[counters::num_unchoke_slots] == (std::numeric_limits<int>::max)());
 
-		for (int l = 0; l < num_torrent_lists; ++l)
+		for (torrent_list_index_t l{}; l != m_torrent_lists.end_index(); ++l)
 		{
 			std::vector<torrent*> const& list = m_torrent_lists[l];
 			for (auto const& i : list)

src/torrent.cpp

@@ -782,7 +782,7 @@ namespace libtorrent {
 		// torrent
 
 #if TORRENT_USE_ASSERTS
-		for (int i = 0; i < aux::session_interface::num_torrent_lists; ++i)
+		for (torrent_list_index_t i{}; i != m_links.end_index(); ++i)
 		{
 			if (!m_links[i].in_list()) continue;
 			m_links[i].unlink(m_ses.torrent_list(i), i);
@@ -4418,7 +4418,7 @@ namespace libtorrent {
 		m_paused = false;
 		m_auto_managed = false;
 		update_state_list();
-		for (int i = 0; i < aux::session_interface::num_torrent_lists; ++i)
+		for (torrent_list_index_t i{}; i != m_links.end_index(); ++i)
 		{
 			if (!m_links[i].in_list()) continue;
 			m_links[i].unlink(m_ses.torrent_list(i), i);
@@ -7113,10 +7113,10 @@ namespace libtorrent {
 	namespace {
 
 #ifndef TORRENT_DISABLE_LOGGING
-	char const* list_name(int idx)
+	char const* list_name(torrent_list_index_t const idx)
 	{
-#define TORRENT_LIST_NAME(n) case aux::session_interface:: n: return #n;
+#define TORRENT_LIST_NAME(n) case static_cast<int>(aux::session_interface:: n): return #n;
-		switch (idx)
+		switch (static_cast<int>(idx))
 		{
 			TORRENT_LIST_NAME(torrent_state_updates);
 			TORRENT_LIST_NAME(torrent_want_tick);
@@ -7135,7 +7135,7 @@ namespace libtorrent {
 
 	} // anonymous namespace
 
-	void torrent::update_list(int list, bool in)
+	void torrent::update_list(torrent_list_index_t const list, bool in)
 	{
 		link& l = m_links[list];
 		aux::vector<torrent*>& v = m_ses.torrent_list(list);
@@ -7742,7 +7742,7 @@ namespace libtorrent {
 		}
 
 #if TORRENT_USE_ASSERTS
-		for (int i = 0; i < aux::session_interface::num_torrent_lists; ++i)
+		for (torrent_list_index_t i{}; i != m_links.end_index(); ++i)
 		{
 			if (!m_links[i].in_list()) continue;
 			int const index = m_links[i].index;