Revert "Implement FromStr for PathBuf"

This reverts commit 05a9acc.

src/libstd/path.rs

@@ -87,7 +87,6 @@ use io;
 use iter::{self, FusedIterator};
 use ops::{self, Deref};
 use rc::Rc;
-use str::FromStr;
 use sync::Arc;
 
 use ffi::{OsStr, OsString};
@@ -1441,32 +1440,6 @@ impl From<String> for PathBuf {
     }
 }
 
-/// Error returned from [`PathBuf::from_str`][`from_str`].
-///
-/// Note that parsing a path will never fail. This error is just a placeholder
-/// for implementing `FromStr` for `PathBuf`.
-///
-/// [`from_str`]: struct.PathBuf.html#method.from_str
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[stable(feature = "path_from_str", since = "1.26.0")]
-pub enum ParsePathError {}
-
-#[stable(feature = "path_from_str", since = "1.26.0")]
-impl fmt::Display for ParsePathError {
-    fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
-        match *self {}
-    }
-}
-
-#[stable(feature = "path_from_str", since = "1.26.0")]
-impl FromStr for PathBuf {
-    type Err = ParsePathError;
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        Ok(PathBuf::from(s))
-    }
-}
-
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<P: AsRef<Path>> iter::FromIterator<P> for PathBuf {
     fn from_iter<I: IntoIterator<Item = P>>(iter: I) -> PathBuf {