This simple program compiles nicely on Linux+gcc 6.3.0 but fails to compile on x86_64-w64-mingw (6.3.0, std=c++14): #include "nowide/fstream.hpp" int main() { auto f = nowide::fstream("toto.log"); return 0; } instead of auto f=..., nowide::fstream f("toto.log") works fine. The error is: toto.cpp:4:38: erreur : use of deleted function « nowide::basic_fstream<char>::basic_fstream(const nowide::basic_fstream<char>&) » auto f = nowide::fstream("toto.log"); ^ In file included from toto.cpp:1:0: nowide/fstream.hpp:190:11: note : « nowide::basic_fstream<char>::basic_fstream(const nowide::basic_fstream<char>&) » is implicitly deleted because the default definition would be ill-formed: class basic_fstream : public std::basic_iostream<CharType,Traits> ^~~~~~~~~~~~~ nowide/fstream.hpp:190:11: erreur : use of deleted function « std::basic_iostream<_CharT, _Traits>::basic_iostream(const std::basic_iostream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_t raits<char>] » In file included from /softs/mingw64-6.3.0/x86_64-w64-mingw32/include/c++/6.3.0/iterator:65:0, from ./nowide/encoding_utf.hpp:14, from ./nowide/convert.hpp:12, from nowide/fstream.hpp:13, from toto.cpp:1: /softs/mingw64-6.3.0/x86_64-w64-mingw32/include/c++/6.3.0/istream:863:7: note : declared here basic_iostream(const basic_iostream&) = delete; ^~~~~~~~~~~~~~ In file included from toto.cpp:1:0: nowide/fstream.hpp:190:11: erreur : use of deleted function « std::basic_ios<_CharT, _Traits>::basic_ios(const std::basic_ios<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>] » class basic_fstream : public std::basic_iostream<CharType,Traits> ^~~~~~~~~~~~~ In file included from /softs/mingw64-6.3.0/x86_64-w64-mingw32/include/c++/6.3.0/ios:44:0, from /softs/mingw64-6.3.0/x86_64-w64-mingw32/include/c++/6.3.0/ostream:38, from /softs/mingw64-6.3.0/x86_64-w64-mingw32/include/c++/6.3.0/iterator:64, from ./nowide/encoding_utf.hpp:14, from ./nowide/convert.hpp:12, from nowide/fstream.hpp:13, from toto.cpp:1: /softs/mingw64-6.3.0/x86_64-w64-mingw32/include/c++/6.3.0/bits/basic_ios.h:475:7: note : declared here basic_ios(const basic_ios&) = delete; ^~~~~~~~~ In file included from toto.cpp:1:0: nowide/fstream.hpp:190:11: erreur : « nowide::scoped_ptr<T>::scoped_ptr(const nowide::scoped_ptr<T>&) [with T = nowide::basic_filebuf<char>] » is private within this context class basic_fstream : public std::basic_iostream<CharType,Traits> ^~~~~~~~~~~~~ In file included from nowide/fstream.hpp:14:0, from toto.cpp:1: ./nowide/scoped_ptr.hpp:31:5: note : declared private here scoped_ptr(scoped_ptr const &);