std: Remove extra type params on iter adaptors

Now that associated types are fully implemented the iterator adaptors only need
type parameters which are associated with actual storage. All other type
parameters can either be derived from these (e.g. they are an associated type)
or can be bare on the `impl` block itself.

This is a breaking change due to the removal of type parameters on these
iterator adaptors, but code can fairly easily migrate by just deleting the
relevant type parameters for each adaptor. Other behavior should not be
affected.

Closes #21839
[breaking-change]

Author: alexcrichton

src/libcollections/btree/map.rs

@@ -116,13 +116,13 @@ pub struct IntoIter<K, V> {
 /// An iterator over a BTreeMap's keys.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Keys<'a, K: 'a, V: 'a> {
-    inner: Map<(&'a K, &'a V), &'a K, Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a K>
+    inner: Map<Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a K>
 }
 
 /// An iterator over a BTreeMap's values.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Values<'a, K: 'a, V: 'a> {
-    inner: Map<(&'a K, &'a V), &'a V, Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a V>
+    inner: Map<Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a V>
 }
 
 /// An iterator over a sub-range of BTreeMap's entries.

src/libcollections/btree/set.rs

@@ -45,40 +45,40 @@ pub struct Iter<'a, T: 'a> {
 /// An owning iterator over a BTreeSet's items.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct IntoIter<T> {
-    iter: Map<(T, ()), T, ::btree_map::IntoIter<T, ()>, fn((T, ())) -> T>
+    iter: Map<::btree_map::IntoIter<T, ()>, fn((T, ())) -> T>
 }
 
 /// An iterator over a sub-range of BTreeSet's items.
 pub struct Range<'a, T: 'a> {
-    iter: Map<(&'a T, &'a ()), &'a T, ::btree_map::Range<'a, T, ()>, fn((&'a T, &'a ())) -> &'a T>
+    iter: Map<::btree_map::Range<'a, T, ()>, fn((&'a T, &'a ())) -> &'a T>
 }
 
 /// A lazy iterator producing elements in the set difference (in-order).
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Difference<'a, T:'a> {
-    a: Peekable<&'a T, Iter<'a, T>>,
-    b: Peekable<&'a T, Iter<'a, T>>,
+    a: Peekable<Iter<'a, T>>,
+    b: Peekable<Iter<'a, T>>,
 }
 
 /// A lazy iterator producing elements in the set symmetric difference (in-order).
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct SymmetricDifference<'a, T:'a> {
-    a: Peekable<&'a T, Iter<'a, T>>,
-    b: Peekable<&'a T, Iter<'a, T>>,
+    a: Peekable<Iter<'a, T>>,
+    b: Peekable<Iter<'a, T>>,
 }
 
 /// A lazy iterator producing elements in the set intersection (in-order).
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Intersection<'a, T:'a> {
-    a: Peekable<&'a T, Iter<'a, T>>,
-    b: Peekable<&'a T, Iter<'a, T>>,
+    a: Peekable<Iter<'a, T>>,
+    b: Peekable<Iter<'a, T>>,
 }
 
 /// A lazy iterator producing elements in the set union (in-order).
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Union<'a, T:'a> {
-    a: Peekable<&'a T, Iter<'a, T>>,
-    b: Peekable<&'a T, Iter<'a, T>>,
+    a: Peekable<Iter<'a, T>>,
+    b: Peekable<Iter<'a, T>>,
 }
 
 impl<T: Ord> BTreeSet<T> {

src/libcollections/vec_map.rs

@@ -687,7 +687,7 @@ double_ended_iterator! { impl IterMut -> (uint, &'a mut V), as_mut }
 /// An iterator over the keys of a map.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Keys<'a, V: 'a> {
-    iter: Map<(uint, &'a V), uint, Iter<'a, V>, fn((uint, &'a V)) -> uint>
+    iter: Map<Iter<'a, V>, fn((uint, &'a V)) -> uint>
 }
 
 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
@@ -702,7 +702,7 @@ impl<'a, V> Clone for Keys<'a, V> {
 /// An iterator over the values of a map.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Values<'a, V: 'a> {
-    iter: Map<(uint, &'a V), &'a V, Iter<'a, V>, fn((uint, &'a V)) -> &'a V>
+    iter: Map<Iter<'a, V>, fn((uint, &'a V)) -> &'a V>
 }
 
 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
@@ -718,17 +718,13 @@ impl<'a, V> Clone for Values<'a, V> {
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct IntoIter<V> {
     iter: FilterMap<
-    (uint, Option<V>),
-    (uint, V),
     Enumerate<vec::IntoIter<Option<V>>>,
     fn((uint, Option<V>)) -> Option<(uint, V)>>
 }
 
 #[unstable(feature = "collections")]
 pub struct Drain<'a, V> {
     iter: FilterMap<
-    (uint, Option<V>),
-    (uint, V),
     Enumerate<vec::Drain<'a, Option<V>>>,
     fn((uint, Option<V>)) -> Option<(uint, V)>>
 }