std: Stabilize the `hash` module

This commit is an implementation of [RFC 823][rfc] which is another pass over
the `std::hash` module for stabilization. The contents of the module were not
entirely marked stable, but some portions which remained quite similar to the
previous incarnation are now marked `#[stable]`. Specifically:

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0823-hash-simplification.md

* `std::hash` is now stable (the name)
* `Hash` is now stable
* `Hash::hash` is now stable
* `Hasher` is now stable
* `SipHasher` is now stable
* `SipHasher::new` and `new_with_keys` are now stable
* `Hasher for SipHasher` is now stable
* Many `Hash` implementations are now stable

All other portions of the `hash` module remain `#[unstable]` as they are less
commonly used and were recently redesigned.

This commit is a breaking change due to the modifications to the `std::hash` API
and more details can be found on the [RFC][rfc].

Closes #22467
[breaking-change]

4 files changed, 92 insertions, 17 deletions

diff --git a/src/libsyntax/ext/deriving/hash.rs b/src/libsyntax/ext/deriving/hash.rs
index 5aa9f9a0c3e..2149c7a7f77 100644
--- a/src/libsyntax/ext/deriving/hash.rs
+++ b/src/libsyntax/ext/deriving/hash.rs
@@ -14,7 +14,6 @@ use ext::base::ExtCtxt;
 use ext::build::AstBuilder;
 use ext::deriving::generic::*;
 use ext::deriving::generic::ty::*;
-use parse::token::InternedString;
 use ptr::P;
 
 pub fn expand_deriving_hash<F>(cx: &mut ExtCtxt,
@@ -26,30 +25,26 @@ pub fn expand_deriving_hash<F>(cx: &mut ExtCtxt,
 {
 
     let path = Path::new_(pathvec_std!(cx, core::hash::Hash), None,
-                          vec!(box Literal(Path::new_local("__S"))), true);
-    let generics = LifetimeBounds {
-        lifetimes: Vec::new(),
-        bounds: vec!(("__S",
-                      vec!(path_std!(cx, core::hash::Writer),
-                           path_std!(cx, core::hash::Hasher)))),
-    };
-    let args = Path::new_local("__S");
-    let inline = cx.meta_word(span, InternedString::new("inline"));
-    let attrs = vec!(cx.attribute(span, inline));
+                          vec!(), true);
+    let arg = Path::new_local("__H");
     let hash_trait_def = TraitDef {
         span: span,
         attributes: Vec::new(),
         path: path,
         additional_bounds: Vec::new(),
-        generics: generics,
+        generics: LifetimeBounds::empty(),
         methods: vec!(
             MethodDef {
                 name: "hash",
-                generics: LifetimeBounds::empty(),
+                generics: LifetimeBounds {
+                    lifetimes: Vec::new(),
+                    bounds: vec![("__H",
+                                  vec![path_std!(cx, core::hash::Hasher)])],
+                },
                 explicit_self: borrowed_explicit_self(),
-                args: vec!(Ptr(box Literal(args), Borrowed(None, MutMutable))),
+                args: vec!(Ptr(box Literal(arg), Borrowed(None, MutMutable))),
                 ret_ty: nil_ty(),
-                attributes: attrs,
+                attributes: vec![],
                 combine_substructure: combine_substructure(box |a, b, c| {
                     hash_substructure(a, b, c)
                 })
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index e8bdcd62b58..3a7fa54edbd 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -28,7 +28,6 @@
 #![feature(collections)]
 #![feature(core)]
 #![feature(env)]
-#![feature(hash)]
 #![feature(int_uint)]
 #![feature(old_io)]
 #![feature(libc)]
diff --git a/src/libsyntax/ptr.rs b/src/libsyntax/ptr.rs
index 01f3839b039..adb5383a8fd 100644
--- a/src/libsyntax/ptr.rs
+++ b/src/libsyntax/ptr.rs
@@ -111,11 +111,18 @@ impl<T: Display> Display for P<T> {
     }
 }
 
+#[cfg(stage0)]
 impl<S: Hasher, T: Hash<S>> Hash<S> for P<T> {
     fn hash(&self, state: &mut S) {
         (**self).hash(state);
     }
 }
+#[cfg(not(stage0))]
+impl<T: Hash> Hash for P<T> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        (**self).hash(state);
+    }
+}
 
 impl<T: 'static + Decodable> Decodable for P<T> {
     fn decode<D: Decoder>(d: &mut D) -> Result<P<T>, D::Error> {
diff --git a/src/libsyntax/util/interner.rs b/src/libsyntax/util/interner.rs
index 51144267519..58b5c44c960 100644
--- a/src/libsyntax/util/interner.rs
+++ b/src/libsyntax/util/interner.rs
@@ -18,9 +18,9 @@ use std::borrow::BorrowFrom;
 use std::cell::RefCell;
 use std::cmp::Ordering;
 use std::collections::HashMap;
+#[cfg(stage0)] use std::collections::hash_map::Hasher;
 use std::fmt;
 use std::hash::Hash;
-use std::collections::hash_map::Hasher;
 use std::ops::Deref;
 use std::rc::Rc;
 
@@ -30,6 +30,7 @@ pub struct Interner<T> {
 }
 
 // when traits can extend traits, we should extend index<Name,T> to get []
+#[cfg(stage0)]
 impl<T: Eq + Hash<Hasher> + Clone + 'static> Interner<T> {
     pub fn new() -> Interner<T> {
         Interner {
@@ -92,6 +93,70 @@ impl<T: Eq + Hash<Hasher> + Clone + 'static> Interner<T> {
         *self.vect.borrow_mut() = Vec::new();
     }
 }
+// when traits can extend traits, we should extend index<Name,T> to get []
+#[cfg(not(stage0))]
+impl<T: Eq + Hash + Clone + 'static> Interner<T> {
+    pub fn new() -> Interner<T> {
+        Interner {
+            map: RefCell::new(HashMap::new()),
+            vect: RefCell::new(Vec::new()),
+        }
+    }
+
+    pub fn prefill(init: &[T]) -> Interner<T> {
+        let rv = Interner::new();
+        for v in init {
+            rv.intern((*v).clone());
+        }
+        rv
+    }
+
+    pub fn intern(&self, val: T) -> Name {
+        let mut map = self.map.borrow_mut();
+        match (*map).get(&val) {
+            Some(&idx) => return idx,
+            None => (),
+        }
+
+        let mut vect = self.vect.borrow_mut();
+        let new_idx = Name((*vect).len() as u32);
+        (*map).insert(val.clone(), new_idx);
+        (*vect).push(val);
+        new_idx
+    }
+
+    pub fn gensym(&self, val: T) -> Name {
+        let mut vect = self.vect.borrow_mut();
+        let new_idx = Name((*vect).len() as u32);
+        // leave out of .map to avoid colliding
+        (*vect).push(val);
+        new_idx
+    }
+
+    pub fn get(&self, idx: Name) -> T {
+        let vect = self.vect.borrow();
+        (*vect)[idx.usize()].clone()
+    }
+
+    pub fn len(&self) -> usize {
+        let vect = self.vect.borrow();
+        (*vect).len()
+    }
+
+    pub fn find<Q: ?Sized>(&self, val: &Q) -> Option<Name>
+    where Q: BorrowFrom<T> + Eq + Hash {
+        let map = self.map.borrow();
+        match (*map).get(val) {
+            Some(v) => Some(*v),
+            None => None,
+        }
+    }
+
+    pub fn clear(&self) {
+        *self.map.borrow_mut() = HashMap::new();
+        *self.vect.borrow_mut() = Vec::new();
+    }
+}
 
 #[derive(Clone, PartialEq, Hash, PartialOrd)]
 pub struct RcStr {
@@ -210,6 +275,7 @@ impl StrInterner {
         self.vect.borrow().len()
     }
 
+    #[cfg(stage0)]
     pub fn find<Q: ?Sized>(&self, val: &Q) -> Option<Name>
     where Q: BorrowFrom<RcStr> + Eq + Hash<Hasher> {
         match (*self.map.borrow()).get(val) {
@@ -217,6 +283,14 @@ impl StrInterner {
             None => None,
         }
     }
+    #[cfg(not(stage0))]
+    pub fn find<Q: ?Sized>(&self, val: &Q) -> Option<Name>
+    where Q: BorrowFrom<RcStr> + Eq + Hash {
+        match (*self.map.borrow()).get(val) {
+            Some(v) => Some(*v),
+            None => None,
+        }
+    }
 
     pub fn clear(&self) {
         *self.map.borrow_mut() = HashMap::new();