u8filesystem is a helper for the std::filesystem library that helps to deal with std::string encoded as UTF-8. One of the current limitations in the design of std::filesystem is the inability to consistently treat std::string as UTF-8 encoded in every platform. According to the C++17 standard:

* char: Encoding is the native narrow encoding

This means that in Windows platform std::string will be treated as ANSI encoded. If cross-platform code is storing UTF-8 encoded string, evey construction of std::filesystem::path with strings must be guarded so it will convert the UTF-8 string to UTF-16 in Windows. Macros can be be used to avoid unneeded conversion in non Windows plaftorms. Also calls to path::string() must be converted to path::u8string(). Still, the need for this precautions is uncovenient and subjected to errors.

A proposed solution is to fully alias all classes and methods of std::filesystem to another namespace, here named std::u8filesystem, so the methods will always treat std::string as UTF-8 encoded. Classes are inheriting their corresponding in std::filesystem, not adding any field or virtual method, to offer full interoperability. Also same names of classes and methods are kept to make it a drop-in replacement solution.

The inner working of the helper is assuming std::string is UTF-8 encoded when constructing std::u8filesystem::path and aliasing path::string() with the same semantics, as summarized in the following snippet:

static std::wstring U8ToW(const char *string);

#ifdef WIN32

path::path(const std::string & path)
    : fs::path(U8ToW(path))
{
}

std::string path::string() const
{
    return filesystem::path::u8string();
}

#endif

std::wstring U8ToW(const char *string)
{
    std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>, wchar_t> convert;
    return convert.from_bytes(string);
}

The helper is still incomplete and currently being tested on Windows platform only.