问题
I wanted to try out the new filesystem library in C++17, so tried copying the std::filesystem::current_path example from cppreference.com and compiling it using the latest version (16.0) of the MinGW distribution from nuwen.net on my Windows 10 x64 machine. This includes gcc v8.1 which should support the filesystem library according to cppreference.com compiler support page.
Here is the code that I am trying to compile:
#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
int main()
{
std::cout << "Current path is " << fs::current_path() << '\n';
}
And the compiler command I am using:
g++ -std=c++17 filesystem_test.cpp
Here is the error I am getting when trying to compile:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h: In member function 'std::filesystem::__cxx11::path& std::filesystem::__cxx11::path::operator/=(const std::filesystem::__cxx11::path&)':
c:\mingw\include\c++\8.1.0\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 c:\mingw\include\c++\8.1.0\iosfwd:40,
from c:\mingw\include\c++\8.1.0\ios:38,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\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)
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\postypes.h:221:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\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 c:\mingw\include\c++\8.1.0\bits\stl_algobase.h:64,
from c:\mingw\include\c++\8.1.0\bits\char_traits.h:39,
from c:\mingw\include\c++\8.1.0\ios:40,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\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)
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\stl_pair.h:456:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'const std::pair<_T1, _T2>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\bits\stl_algobase.h:67,
from c:\mingw\include\c++\8.1.0\bits\char_traits.h:39,
from c:\mingw\include\c++\8.1.0\ios:40,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\stl_iterator.h:311:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)'
operator!=(const reverse_iterator<_Iterator>& __x,
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\stl_iterator.h:311:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'const std::reverse_iterator<_Iterator>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\bits\stl_algobase.h:67,
from c:\mingw\include\c++\8.1.0\bits\char_traits.h:39,
from c:\mingw\include\c++\8.1.0\ios:40,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\stl_iterator.h:349:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)'
operator!=(const reverse_iterator<_IteratorL>& __x,
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\stl_iterator.h:349:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'const std::reverse_iterator<_Iterator>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\bits\stl_algobase.h:67,
from c:\mingw\include\c++\8.1.0\bits\char_traits.h:39,
from c:\mingw\include\c++\8.1.0\ios:40,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\stl_iterator.h:1124:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&)'
operator!=(const move_iterator<_IteratorL>& __x,
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\stl_iterator.h:1124:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'const std::move_iterator<_IteratorL>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\bits\stl_algobase.h:67,
from c:\mingw\include\c++\8.1.0\bits\char_traits.h:39,
from c:\mingw\include\c++\8.1.0\ios:40,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\stl_iterator.h:1130:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorL>&)'
operator!=(const move_iterator<_Iterator>& __x,
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\stl_iterator.h:1130:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'const std::move_iterator<_IteratorL>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\string:41,
from c:\mingw\include\c++\8.1.0\bits\locale_classes.h:40,
from c:\mingw\include\c++\8.1.0\bits\ios_base.h:41,
from c:\mingw\include\c++\8.1.0\ios:42,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\allocator.h:158:5: note: candidate: 'template<class _T1, class _T2> bool std::operator!=(const std::allocator<_CharT>&, const std::allocator<_T2>&)'
operator!=(const allocator<_T1>&, const allocator<_T2>&)
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\allocator.h:158:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'const std::allocator<_CharT>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\string:41,
from c:\mingw\include\c++\8.1.0\bits\locale_classes.h:40,
from c:\mingw\include\c++\8.1.0\bits\ios_base.h:41,
from c:\mingw\include\c++\8.1.0\ios:42,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\allocator.h:164:5: note: candidate: 'template<class _Tp> bool std::operator!=(const std::allocator<_CharT>&, const std::allocator<_CharT>&)'
operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\allocator.h:164:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'const std::allocator<_CharT>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\bits\basic_string.h:48,
from c:\mingw\include\c++\8.1.0\string:52,
from c:\mingw\include\c++\8.1.0\bits\locale_classes.h:40,
from c:\mingw\include\c++\8.1.0\bits\ios_base.h:41,
from c:\mingw\include\c++\8.1.0\ios:42,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\string_view:454:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(std::basic_string_view<_CharT, _Traits>, std::basic_string_view<_CharT, _Traits>)'
operator!=(basic_string_view<_CharT, _Traits> __x,
^~~~~~~~
c:\mingw\include\c++\8.1.0\string_view:454:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'std::basic_string_view<_CharT, _Traits>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\bits\basic_string.h:48,
from c:\mingw\include\c++\8.1.0\string:52,
from c:\mingw\include\c++\8.1.0\bits\locale_classes.h:40,
from c:\mingw\include\c++\8.1.0\bits\ios_base.h:41,
from c:\mingw\include\c++\8.1.0\ios:42,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\string_view:460:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(std::basic_string_view<_CharT, _Traits>, std::__detail::__idt<std::basic_string_view<_CharT, _Traits> >)'
operator!=(basic_string_view<_CharT, _Traits> __x,
^~~~~~~~
c:\mingw\include\c++\8.1.0\string_view:460:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'std::basic_string_view<_CharT, _Traits>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\bits\basic_string.h:48,
from c:\mingw\include\c++\8.1.0\string:52,
from c:\mingw\include\c++\8.1.0\bits\locale_classes.h:40,
from c:\mingw\include\c++\8.1.0\bits\ios_base.h:41,
from c:\mingw\include\c++\8.1.0\ios:42,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\string_view:466:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(std::__detail::__idt<std::basic_string_view<_CharT, _Traits> >, std::basic_string_view<_CharT, _Traits>)'
operator!=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
^~~~~~~~
c:\mingw\include\c++\8.1.0\string_view:466:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'std::basic_string_view<_CharT, _Traits>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\string:52,
from c:\mingw\include\c++\8.1.0\bits\locale_classes.h:40,
from c:\mingw\include\c++\8.1.0\bits\ios_base.h:41,
from c:\mingw\include\c++\8.1.0\ios:42,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\basic_string.h:6056:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator!=(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)'
operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\basic_string.h:6056:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: 'std::filesystem::__cxx11::path' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\string:52,
from c:\mingw\include\c++\8.1.0\bits\locale_classes.h:40,
from c:\mingw\include\c++\8.1.0\bits\ios_base.h:41,
from c:\mingw\include\c++\8.1.0\ios:42,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\basic_string.h:6069:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator!=(const _CharT*, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)'
operator!=(const _CharT* __lhs,
^~~~~~~~
c:\mingw\include\c++\8.1.0\bits\basic_string.h:6069:5: note: template argument deduction/substitution failed:
In file included from c:\mingw\include\c++\8.1.0\filesystem:37,
from filesystem_test.cpp:2:
c:\mingw\include\c++\8.1.0\bits\fs_path.h:237:60: note: mismatched types 'const _CharT*' and 'std::filesystem::__cxx11::path'
|| (__p.has_root_name() && __p.root_name() != root_name()))
^
In file included from c:\mingw\include\c++\8.1.0\string:52,
from c:\mingw\include\c++\8.1.0\bits\locale_classes.h:40,
from c:\mingw\include\c++\8.1.0\bits\ios_base.h:41,
from c:\mingw\include\c++\8.1.0\ios:42,
from c:\mingw\include\c++\8.1.0\ostream:38,
from c:\mingw\include\c++\8.1.0\iostream:39,
from filesystem_test.cpp:1:
c:\mingw\include\c++\8.1.0\bits\basic_string.h:6081:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator!=(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)'
operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
^~~~~~~~
<snip>
Note I had to snip the end of the error message to reduce the character count for this question. I have put the entire error message here: https://pastebin.com/pnfMnMs7
Edit: As per Galik's comment, I tried changing my compiler command to
g++ -std=c++17 filesystem_test.cpp -lstdc++fs
However I seem to get exactly the same error as before
回答1:
try latest msys2 instead of nuwen distro:
pacman -Syu
pacman -S mingw-w64-x86_64-gcc
gcc -v
$ gcc -v Using built-in specs. COLLECT_GCC=C:\msys64\mingw64\bin\gcc.exe COLLECT_LTO_WRAPPER=C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.2.0/lto-wrapper.exe Target: x86_64-w64-mingw32 Configured with: ../gcc-8.2.0/configure --prefix=/mingw64 --with-local-prefix=/mingw64/local --build=x86_64-w64-mingw32 --host=x86_64-w64-mingw32 --target=x86_64-w64-mingw32 --with-native-system-header-dir=/mingw64/x86_64-w64-mingw32/include --libexecdir=/mingw64/lib --enable-bootstrap --with-arch=x86-64 --with-tune=generic --enable-languages=ada,c,lto,c++,objc,obj-c++,fortran --enable-shared --enable-static --enable-libatomic --enable-threads=posix --enable-graphite --enable-fully-dynamic-string --enable-libstdcxx-filesystem-ts=yes --enable-libstdcxx-time=yes --disable-libstdcxx-pch --disable-libstdcxx-debug --disable-isl-version-check --enable-lto --enable-libgomp --disable-multilib --enable-checking=release --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-libiconv --with-system-zlib --with-gmp=/mingw64 --with-mpfr=/mingw64 --with-mpc=/mingw64 --with-isl=/mingw64 --with-pkgversion='Rev1, Built by MSYS2 project' --with-bugurl=https://sourceforge.net/projects/msys2 --with-gnu-as --with-gnu-ld Thread model: posix gcc version 8.2.0 (Rev1, Built by MSYS2 project)
来源：https://stackoverflow.com/questions/52342522/c17-filesystem-using-nuwen-mingw-on-windows-10