With Boost 1.78 (installed on my system), I get a compiler error:

```
./fs.h: In function ‘fs::path fs::operator+(fs::path, fs::path)’:
./fs.h:91:8: error: no match for ‘operator+=’ (operand types are ‘fs::path’ and ‘std::remove_reference<fs::path&>::type’ {aka ‘fs::path’})
   91 |     p1 += std::move(p2);
      |     ~~~^~~~~~~~~~~~~~~~
```

It appears that in Boost 1.78, `operator+=` became a template function, and our `path` class which subclasses `boost::filesystem::path::path` no longer has an `operator+=` which will work with it.

I also opened an issue with boost: https://github.com/boostorg/filesystem/issues/223
{
    
    
    
    
    
    
    
    
    
    
#ifdef WIN32
    return path.u8string();
#else
    static_assert(std::is_same<path::string_type, std::string>::value, "PathToString not implemented on this platform");
    return path.boost::filesystem::path::string();
#endif
}
/**
 * Convert byte string to path object. Inverse of \ref PathToString.
 */
static inline path PathFromString(const std::string& string)