Don't implement `NixPath` for `Option<&P> where P: NixPath`

Most Nix functions that accept `NixPath` arguments can't do anything
useful with `None`.  The exceptions (`mount` and `quotactl_sync`)
already take explicitly optional arguments.

Also, this changes the behavior of `mount` with `None` arguments.
Previously, it would call mount(2) with empty strings for those
arguments.  Now, it will use null pointers.

1 files changed, 0 insertions, 19 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 0ba7ace8..51751f9e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -283,22 +283,3 @@ impl NixPath for PathBuf {
         self.as_os_str().with_nix_path(f)
     }
 }
-
-/// Treats `None` as an empty string.
-impl<'a, NP: ?Sized + NixPath>  NixPath for Option<&'a NP> {
-    fn is_empty(&self) -> bool {
-        self.map_or(true, NixPath::is_empty)
-    }
-
-    fn len(&self) -> usize {
-        self.map_or(0, NixPath::len)
-    }
-
-    fn with_nix_path<T, F>(&self, f: F) -> Result<T> where F: FnOnce(&CStr) -> T {
-        if let Some(nix_path) = *self {
-            nix_path.with_nix_path(f)
-        } else {
-            unsafe { CStr::from_ptr("\0".as_ptr() as *const _).with_nix_path(f) }
-        }
-    }
-}