rollup merge of #22210: aturon/stab-final-borrow

Conflicts:
	src/libcollections/btree/map.rs
	src/libcollections/str.rs
	src/libcollections/vec.rs
	src/libcore/borrow.rs
	src/libcore/hash/mod.rs
	src/libstd/collections/hash/map.rs
	src/libstd/collections/hash/set.rs

5 files changed, 33 insertions, 28 deletions

diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index 04f8bb0b0db..ade4f1f0533 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -14,7 +14,7 @@ use self::Entry::*;
 use self::SearchResult::*;
 use self::VacantEntryState::*;
 
-use borrow::BorrowFrom;
+use borrow::Borrow;
 use clone::Clone;
 use cmp::{max, Eq, PartialEq};
 use default::Default;
@@ -451,18 +451,18 @@ impl<K, V, S> HashMap<K, V, S>
     /// If you already have the hash for the key lying around, use
     /// search_hashed.
     fn search<'a, Q: ?Sized>(&'a self, q: &Q) -> Option<FullBucketImm<'a, K, V>>
-        where Q: BorrowFrom<K> + Eq + Hash
+        where K: Borrow<Q>, Q: Eq + Hash
     {
         let hash = self.make_hash(q);
-        search_hashed(&self.table, hash, |k| q.eq(BorrowFrom::borrow_from(k)))
+        search_hashed(&self.table, hash, |k| q.eq(k.borrow()))
             .into_option()
     }
 
     fn search_mut<'a, Q: ?Sized>(&'a mut self, q: &Q) -> Option<FullBucketMut<'a, K, V>>
-        where Q: BorrowFrom<K> + Eq + Hash
+        where K: Borrow<Q>, Q: Eq + Hash
     {
         let hash = self.make_hash(q);
-        search_hashed(&mut self.table, hash, |k| q.eq(BorrowFrom::borrow_from(k)))
+        search_hashed(&mut self.table, hash, |k| q.eq(k.borrow()))
             .into_option()
     }
 
@@ -1033,7 +1033,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
-        where Q: Hash + Eq + BorrowFrom<K>
+        where K: Borrow<Q>, Q: Hash + Eq
     {
         self.search(k).map(|bucket| bucket.into_refs().1)
     }
@@ -1056,7 +1056,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
-        where Q: Hash + Eq + BorrowFrom<K>
+        where K: Borrow<Q>, Q: Hash + Eq
     {
         self.search(k).is_some()
     }
@@ -1082,7 +1082,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
-        where Q: Hash + Eq + BorrowFrom<K>
+        where K: Borrow<Q>, Q: Hash + Eq
     {
         self.search_mut(k).map(|bucket| bucket.into_mut_refs().1)
     }
@@ -1134,7 +1134,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
-        where Q: Hash + Eq + BorrowFrom<K>
+        where K: Borrow<Q>, Q: Hash + Eq
     {
         if self.table.size() == 0 {
             return None
@@ -1236,8 +1236,8 @@ impl<K, V, S> Default for HashMap<K, V, S>
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K, Q: ?Sized, V, S> Index<Q> for HashMap<K, V, S>
-    where K: Eq + Hash,
-          Q: Eq + Hash + BorrowFrom<K>,
+    where K: Eq + Hash + Borrow<Q>,
+          Q: Eq + Hash,
           S: HashState,
 {
     type Output = V;
@@ -1250,8 +1250,8 @@ impl<K, Q: ?Sized, V, S> Index<Q> for HashMap<K, V, S>
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K, V, S, Q: ?Sized> IndexMut<Q> for HashMap<K, V, S>
-    where K: Eq + Hash,
-          Q: Eq + Hash + BorrowFrom<K>,
+    where K: Eq + Hash + Borrow<Q>,
+          Q: Eq + Hash,
           S: HashState,
 {
     #[inline]
diff --git a/src/libstd/collections/hash/set.rs b/src/libstd/collections/hash/set.rs
index 751dc86f533..e0631a64d44 100644
--- a/src/libstd/collections/hash/set.rs
+++ b/src/libstd/collections/hash/set.rs
@@ -10,7 +10,7 @@
 //
 // ignore-lexer-test FIXME #15883
 
-use borrow::BorrowFrom;
+use borrow::Borrow;
 use clone::Clone;
 use cmp::{Eq, PartialEq};
 use core::marker::Sized;
@@ -460,7 +460,7 @@ impl<T, S> HashSet<T, S>
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn contains<Q: ?Sized>(&self, value: &Q) -> bool
-        where Q: BorrowFrom<T> + Hash + Eq
+        where T: Borrow<Q>, Q: Hash + Eq
     {
         self.map.contains_key(value)
     }
@@ -570,7 +570,7 @@ impl<T, S> HashSet<T, S>
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool
-        where Q: BorrowFrom<T> + Hash + Eq
+        where T: Borrow<Q>, Q: Hash + Eq
     {
         self.map.remove(value).is_some()
     }
diff --git a/src/libstd/ffi/os_str.rs b/src/libstd/ffi/os_str.rs
index 4e50e1c293f..feace0bd702 100644
--- a/src/libstd/ffi/os_str.rs
+++ b/src/libstd/ffi/os_str.rs
@@ -34,7 +34,7 @@
 
 use core::prelude::*;
 
-use core::borrow::{BorrowFrom, ToOwned};
+use borrow::{Borrow, ToOwned};
 use fmt::{self, Debug};
 use mem;
 use string::{String, CowString};
@@ -285,11 +285,12 @@ impl Debug for OsStr {
     }
 }
 
-impl BorrowFrom<OsString> for OsStr {
-    fn borrow_from(owned: &OsString) -> &OsStr { &owned[] }
+impl Borrow<OsStr> for OsString {
+    fn borrow(&self) -> &OsStr { &self[] }
 }
 
-impl ToOwned<OsString> for OsStr {
+impl ToOwned for OsStr {
+    type Owned = OsString;
     fn to_owned(&self) -> OsString { self.to_os_string() }
 }
 
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index 7c9a8a7b4b5..fbd403ea593 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -161,7 +161,6 @@ extern crate libc;
 // NB: These reexports are in the order they should be listed in rustdoc
 
 pub use core::any;
-pub use core::borrow;
 pub use core::cell;
 pub use core::clone;
 #[cfg(not(test))] pub use core::cmp;
@@ -184,6 +183,7 @@ pub use core::error;
 #[cfg(not(test))] pub use alloc::boxed;
 pub use alloc::rc;
 
+pub use core_collections::borrow;
 pub use core_collections::fmt;
 pub use core_collections::slice;
 pub use core_collections::str;
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index 2ad07462f20..3d95d0f19d1 100755
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -108,12 +108,11 @@
 use core::prelude::*;
 
 use ascii::*;
-use borrow::BorrowFrom;
+use borrow::{Borrow, ToOwned, Cow};
 use cmp;
 use iter::{self, IntoIterator};
 use mem;
 use ops::{self, Deref};
-use string::CowString;
 use vec::Vec;
 use fmt;
 
@@ -982,12 +981,17 @@ impl ops::Deref for PathBuf {
     }
 }
 
-impl BorrowFrom<PathBuf> for Path {
-    fn borrow_from(owned: &PathBuf) -> &Path {
-        owned.deref()
+impl Borrow<Path> for PathBuf {
+    fn borrow(&self) -> &Path {
+        self.deref()
     }
 }
 
+impl ToOwned for Path {
+    type Owned = PathBuf;
+    fn to_owned(&self) -> PathBuf { self.to_path_buf() }
+}
+
 impl cmp::PartialEq for PathBuf {
     fn eq(&self, other: &PathBuf) -> bool {
         self.components() == other.components()
@@ -1066,10 +1070,10 @@ impl Path {
         self.inner.to_str()
     }
 
-    /// Convert a `Path` to a `CowString`.
+    /// Convert a `Path` to a `Cow<str>`.
     ///
     /// Any non-Unicode sequences are replaced with U+FFFD REPLACEMENT CHARACTER.
-    pub fn to_string_lossy(&self) -> CowString {
+    pub fn to_string_lossy(&self) -> Cow<str> {
         self.inner.to_string_lossy()
     }