Errors using <filesystem> C++17

Question

I'm trying to search trough a directory and list all the entries from that directory in a non-platform dependant way. For this I've tried using std::filesystem, however, I'm having tons of compilation errors when trying to use the functions defined there.

This is the sample code I'm trying to run (EDIT: Even If I remove the for loop and just leave the 'return 0', I get the same errors):

#include <iostream>
#include <string>
#include <filesystem>

int main()
{
   for (const auto & entry : std::filesystem::directory_iterator("D:\\fac_2ano2semestre"))
        std::cout << entry.path() << std::endl;

    return 0;
}

This is the output of g++ --version:

g++.exe (x86_64-posix-seh-rev0, Built by MinGW-W64 project) 8.1.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

This is a sample from my Makefile (I've also tried -lstdc++fs):

# Compiler
CXX := g++

# Add whatever compiler flags you want.
CXXFLAGS := -std=c++17 
CXXFLAGS += -Wall -g 

# You MUST keep this for auto-dependency generation.
CXXFLAGS += -MMD

A very SMALL portion of the errors I'm receiving:

g++ -std=c++17  -Wall -g  -MMD   -c -o src/app.o src/app.cpp
In file included from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/filesystem:37,
                 from src/app.cpp:3:
D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/fs_path.h: In member function 'std::filesystem::__cxx11::path& std::filesystem::__cxx11::path::operator/=(const std::filesystem::__cxx11::path&)':
D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/fs_path.h:237:47: error: no match for 'operator!=' (operand types are 'std::filesystem::__cxx11::path' and 'std::filesystem::__cxx11::path')
    || (__p.has_root_name() && __p.root_name() != root_name()))
                               ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
In file included from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/iosfwd:40,
                 from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/ios:38,
                 from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/ostream:38,
                 from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/iostream:39,
                 from src/app.cpp:1:
D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/postypes.h:221:5: note: candidate: 'template<class _StateT> bool std::operator!=(const std::fpos<_StateT>&, const std::fpos<_StateT>&)'
     operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
     ^~~~~~~~
D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/postypes.h:221:5: note:   template argument deduction/substitution failed:
In file included from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/filesystem:37,
                 from src/app.cpp:3:
D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/fs_path.h:237:60: note:   'std::filesystem::__cxx11::path' is not derived from 'const std::fpos<_StateT>'
    || (__p.has_root_name() && __p.root_name() != root_name()))
                                                            ^
In file included from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/stl_algobase.h:64,
                 from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/char_traits.h:39,
                 from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/ios:40,
                 from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/ostream:38,
                 from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/iostream:39,
                 from src/app.cpp:1:
D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/stl_pair.h:456:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator!=(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)'
     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
     ^~~~~~~~
D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/stl_pair.h:456:5: note:   template argument deduction/substitution failed:
In file included from D:/mingw/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/filesystem:37,
                 from src/app.cpp:3:

Answer 1

Download the latest version of the compiler from here: http://winlibs.com/ Then just extract it to override the current mingw-64 you have as is. Update the PATH if needed. I had the same problem and it fixed it.