These warnings have not been fixed because the are legitimate and/or I don't know how to fix them:
test\googletest\googletest\include\gtest/gtest-printers.h(888,43): warning C4996: 'std::tr1': warning STL4002: The non-Standard std::tr1 namespace and TR1-only machinery are deprecated and will be REMOVED.
lib\serializer\JsonSerializeFormat.h(523,26): warning C4244: 'argument': conversion from 'type1' to 'type2', possible loss of data
include\boost/iostreams/positioning.hpp(96,15): warning C4996: 'std::fpos<_Mbstatet>::seekpos': warning STL4019: The member std::fpos::seekpos() is non-Standard, ...
source\lib\filesystem\FileStream.h(39,69): warning C4910: 'boost::iostreams::stream<FileBuf,std::char_traits<char>,std::allocator<char>>': '__declspec(dllexport)' and 'extern' are incompatible on an explicit instantiation
include\boost/optional/optional.hpp(274,53): warning C4244: 'argument': conversion from 'T' to 'T', possible loss of data
client\widgets\../gui/SDL_Extensions.h(112,14): warning C4244: 'initializing': conversion from 'type1' to 'type2', possible loss of data
client\CServerHandler.cpp(421,24): warning C4834: discarding return value of function with 'nodiscard' attribute (see https://bugs.vcmi.eu/view.php?id=3144)
client\CVideoHandler.cpp(130,25): warning C4996: 'AVStream::codec': was declared deprecated