fixed span::fist logic and minor cleanup (#960)

include/libtorrent/bt_peer_connection.hpp

@@ -451,4 +451,3 @@ private:
 }
 
 #endif // TORRENT_BT_PEER_CONNECTION_HPP_INCLUDED
-

include/libtorrent/extensions.hpp

@@ -162,10 +162,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include <vector>
 #include "libtorrent/config.hpp"
-#include "libtorrent/buffer.hpp"
-#include "libtorrent/socket.hpp"
 #include "libtorrent/sha1_hash.hpp" // for sha1_hash
-#include "libtorrent/error_code.hpp"
 #include "libtorrent/session_handle.hpp"
 #include "libtorrent/peer_connection_handle.hpp"
 #include "libtorrent/span.hpp"
@@ -268,7 +265,7 @@ namespace libtorrent
 		{ return std::numeric_limits<uint64_t>::max(); }
 
 		// called when saving settings state
-		virtual void save_state(entry&) const {}
+		virtual void save_state(entry&) {}
 
 		// called when loading settings state
 		virtual void load_state(bdecode_node const&) {}

include/libtorrent/identify_client.hpp

@@ -47,7 +47,7 @@ POSSIBILITY OF SUCH DAMAGE.
 namespace libtorrent
 {
 
-	// TODO: hide these declarations when deprecaated functions are disabled, and
+	// TODO: hide these declarations when deprecated functions are disabled, and
 	// expose them internally in a header under aux_.
 
 	// these functions don't really need to be public. This mechanism of
@@ -70,4 +70,3 @@ namespace libtorrent
 }
 
 #endif // TORRENT_IDENTIFY_CLIENT_HPP_INCLUDED
-

include/libtorrent/span.hpp

@@ -83,7 +83,7 @@ namespace libtorrent
 		span<T> first(size_t const n) const
 		{
 			TORRENT_ASSERT(size() >= n);
-			return { data(), size() - n };
+			return { data(), n };
 		}
 
 		span<T> last(size_t const n) const

src/bt_peer_connection.cpp

@@ -64,7 +64,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/io.hpp"
 #include "libtorrent/aux_/io.hpp"
 #include "libtorrent/socket_io.hpp"
-#include "libtorrent/version.hpp"
 #include "libtorrent/extensions.hpp"
 #include "libtorrent/aux_/session_interface.hpp"
 #include "libtorrent/alert_types.hpp"
@@ -753,7 +752,7 @@ namespace libtorrent
 
 		// add handshake to the send buffer
 		const char version_string[] = "BitTorrent protocol";
-		const int string_len = sizeof(version_string)-1;
+		const int string_len = sizeof(version_string) - 1;
 
 		char handshake[1 + string_len + 8 + 20 + 20];
 		char* ptr = handshake;

src/http_connection.cpp

@@ -745,7 +745,7 @@ void http_connection::on_read(error_code const& e
 	{
 		span<char const> rcv_buf(m_recvbuffer);
 		bool error = false;
-		m_parser.incoming(rcv_buf.subspan(0, m_read_pos), error);
+		m_parser.incoming(rcv_buf.first(m_read_pos), error);
 		if (error)
 		{
 			// HTTP parse error

src/receive_buffer.cpp

@@ -320,7 +320,7 @@ span<char const> crypto_receive_buffer::get() const
 {
 	span<char const> recv_buffer = m_connection_buffer.get();
 	if (m_recv_pos < m_connection_buffer.pos())
-		recv_buffer = recv_buffer.subspan(0, m_recv_pos);
+		recv_buffer = recv_buffer.first(m_recv_pos);
 	return recv_buffer;
 }