Convert from `&PathBuf` to `PathBuf`

This seems to be a very simple question, but I haven’t got a clue from the documentation. The code creates a PathBuf from &PathBuf. I wonder what makes this possible. The documentation has an implementation that creates a String from &String, but doesn’t have one such implementation for PathBuf? What’s happening behind the scene? And what tools/methods can help me debug/investigate?

fn main() {
    let a = std::path::PathBuf::from("");
    let b = std::path::PathBuf::from(&a);
}

>Solution :

It goes via OsStr.

PathBuf has an implementation impl AsRef<OsStr> for Path and an implementation impl<T: AsRef<OsStr>> From<&T> for PathBuf

Incidentally, this is how the case works for a as well. PathBuf doesn’t implement From<&str> but &str does implement AsRef<OsStr>.