boost/filesystem.hpp warning c4244 (MSVC2019)

[klasing]

Inside a C++ class I created the following member function.
VOID write_logfile(const tuple_logging& tl) { // write tuple to file wofs.open(p, std::ios_base::app); // results in a compiler warning: // warning C4244: ... // TODO: get rid of this warning wofs << boost::tuples::set_delimiter(L'#') << tl << L'\n'; wofs.close(); }
The relevant member variables are:
boost::filesystem::wofstream wofs;
The tuple, named tl, is constructed with std::wstring elements
The relevant includes are:
#include <boost/filesystem.hpp> #include <boost/tuple/tuple.hpp> #include <boost/tuple/tuple_io.hpp>
The compiler inside the MSVC2019 IDE gives me the following warning.
warning C4244: 'argument': conversion from 'const CharType' to 'const char', possible loss of data (and a lot more of this stuff) On the following statement.
wofs << boost::tuples::set_delimiter(L'#') << tl << L'\n';
Can someone help me to get rid of this warning?
`

[Lastique]

Can you provide the complete warning text?

[klasing]

Hello Andrey, here comes the complete compiler output, when I build the project, named ManageServer_1. I hope this can be of any help to you. Thanks in advance for your response. Martijn 1>------ Rebuild All started: Project: ManageServer_1, Configuration: Debug Win32 ------ 1>http_server_async.cpp 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(71,4): warning C4390: ';': empty controlled statement found; is this the intent? 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: 'argument': conversion from 'const CharType' to 'const char', possible loss of data 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: with 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: [ 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: CharType=wchar_t 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: ] 1>main.cpp 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : see reference to function template instantiation 'boost::tuples::tuple_manipulator<wchar_t> boost::tuples::set_delimiter<wchar_t>(const CharType)' being compiled 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : with 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : [ 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : CharType=wchar_t 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : ] 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(71,4): warning C4390: ';': empty controlled statement found; is this the intent? 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: 'argument': conversion from 'const CharType' to 'const char', possible loss of data 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: with 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: [ 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: CharType=wchar_t 1>C:\Program Files\boost\boost_1_70_0\boost\tuple\tuple_io.hpp(142,71): warning C4244: ] 1>Generating Code... 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : see reference to function template instantiation 'boost::tuples::tuple_manipulator<wchar_t> boost::tuples::set_delimiter<wchar_t>(const CharType)' being compiled 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : with 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : [ 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : CharType=wchar_t 1>C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\ManageServer_1\ServerLogging.hpp(85): message : ] 1>ManageServer_1.vcxproj -> C:\Users\Klasing\MyProgramming\MyCpp\Projects_2019\martha\martha\Debug\ManageServer_1.exe 1>Done building project "ManageServer_1.vcxproj". ========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ========== Verzonden vanuit Mail voor Windows 10 Van: Andrey Semashev Verzonden: zondag 15 september 2019 12:28 Aan: boostorg/filesystem CC: klasing; Author Onderwerp: Re: [boostorg/filesystem] boost/filesystem.hpp warning c4244(MSVC2019) (#118) Can you provide the complete warning text? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

[Lastique]

The problem is in Boost.Tuple. The implicit conversion that causes the warning happens because of this constructor argument, which should have type CharType.