Fix compilation on nightly Rust

src/imp/platform/macos.rs

@@ -1,13 +1,13 @@
 use AppDataType::*;
 use common::*;
 use std::env::home_dir;
-use std::path::{Component, PathBuf};
+use std::path::{Component, Path, PathBuf};
 
 pub const USE_AUTHOR: bool = false;
 
 pub fn get_app_dir(t: AppDataType) -> Result<PathBuf, AppDirsError> {
     let dir_base: Result<PathBuf, AppDirsError> = if t.is_shared() {
-        Ok(Component::RootDir.as_ref().into())
+        Ok(Path::new(&Component::RootDir).into())
     } else {
         home_dir().ok_or_else(|| AppDirsError::NotSupported)
     };