rollup merge of #23753: aturon/revise-convert

This commit revises `path` and `os_str` to use blanket impls for `From`
on reference types. This both cuts down on the number of required impls,
and means that you can pass through e.g. `T: AsRef<OsStr>` to
`PathBuf::from` without an intermediate call to `as_ref`.

It also makes a FIXME note for later generalizing the blanket impls for
`AsRef` and `AsMut` to use `Deref`/`DerefMut`, once it is possible to do
so.

1 files changed, 6 insertions, 34 deletions

diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index 50f79967f55..58d3ae9f7cf 100644
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -1038,23 +1038,16 @@ impl PathBuf {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> From<&'a Path> for PathBuf {
-    fn from(s: &'a Path) -> PathBuf {
-        s.to_path_buf()
+impl<'a, T: ?Sized + AsRef<OsStr>> From<&'a T> for PathBuf {
+    fn from(s: &'a T) -> PathBuf {
+        PathBuf::from(s.as_ref().to_os_string())
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> From<&'a str> for PathBuf {
-    fn from(s: &'a str) -> PathBuf {
-        PathBuf::from(OsString::from(s))
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> From<&'a String> for PathBuf {
-    fn from(s: &'a String) -> PathBuf {
-        PathBuf::from(OsString::from(s))
+impl From<OsString> for PathBuf {
+    fn from(s: OsString) -> PathBuf {
+        PathBuf { inner: s }
     }
 }
 
@@ -1066,27 +1059,6 @@ impl From<String> for PathBuf {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> From<&'a OsStr> for PathBuf {
-    fn from(s: &'a OsStr) -> PathBuf {
-        PathBuf::from(OsString::from(s))
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> From<&'a OsString> for PathBuf {
-    fn from(s: &'a OsString) -> PathBuf {
-        PathBuf::from(s.to_os_string())
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl From<OsString> for PathBuf {
-    fn from(s: OsString) -> PathBuf {
-        PathBuf { inner: 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 {
         let mut buf = PathBuf::new();