]pi@raspberrypi:~/Downloads/qbittorrent-4.0.1 $ make
cd src/ && ( test -e Makefile || /usr/lib/arm-linux-gnueabihf/qt5/bin/qmake /home/pi/Downloads/qbittorrent-4.0.1/src/src.pro QMAKE_LRELEASE= -o Makefile ) && make -f Makefile
make[1]: Entering directory '/home/pi/Downloads/qbittorrent-4.0.1/src'
compiling base/bittorrent/infohash.cpp
base/bittorrent/infohash.cpp: In constructor ‘BitTorrent::InfoHash::InfoHash(const sha1_hash&)’:
base/bittorrent/infohash.cpp:43:43: error: invalid operands of types ‘std::size_t() {aka unsigned int()}’ and ‘int’ to binary ‘operator*’
char out[(libtorrent::sha1_hash::size * 2) + 1];
~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
base/bittorrent/infohash.cpp:44:5: error: ‘to_hex’ is not a member of ‘libtorrent’
libtorrent::to_hex(reinterpret_cast<const char*>(&m_nativeHash[0]), libtorrent::sha1_hash::size, out);
^~~~~~~~~~
base/bittorrent/infohash.cpp:44:102: error: ‘out’ was not declared in this scope
terpret_cast<const char*>(&m_nativeHash[0]), libtorrent::sha1_hash::size, out);
^~~
base/bittorrent/infohash.cpp: In constructor ‘BitTorrent::InfoHash::InfoHash(const QString&)’:
base/bittorrent/infohash.cpp:54:19: error: ‘from_hex’ is not a member of ‘libtorrent’
m_valid = libtorrent::from_hex(raw.constData(), 40, reinterpret_cast<char*>(&m_nativeHash[0]));
^~~~~~~~~~
Makefile recipe for target 'infohash.o' failed
make[1]: *** [infohash.o] Error 1
make[1]: Leaving directory '/home/pi/Downloads/qbittorrent-4.0.1/src'
Makefile:42: recipe for target 'sub-src-make_first' failed
make: *** [sub-src-make_first] Error 2
thanks for your help!