diff --git a/src/libextra/dlist.rs b/src/libextra/dlist.rs
index 77060c4b11e3..3cd2d91459f2 100644
--- a/src/libextra/dlist.rs
+++ b/src/libextra/dlist.rs
@@ -356,7 +356,7 @@ impl<T> DList<T> {
 
     /// Provide a reverse iterator
     #[inline]
-    pub fn rev_iter<'a>(&'a self) -> InvertIterator<&'a T, DListIterator<'a, T>> {
+    pub fn rev_iter<'a>(&'a self) -> InvertIterator<DListIterator<'a, T>> {
         self.iter().invert()
     }
 
@@ -376,8 +376,7 @@ impl<T> DList<T> {
     }
     /// Provide a reverse iterator with mutable references
     #[inline]
-    pub fn mut_rev_iter<'a>(&'a mut self) -> InvertIterator<&'a mut T,
-                                                MutDListIterator<'a, T>> {
+    pub fn mut_rev_iter<'a>(&'a mut self) -> InvertIterator<MutDListIterator<'a, T>> {
         self.mut_iter().invert()
     }
 
@@ -390,7 +389,7 @@ impl<T> DList<T> {
 
     /// Consume the list into an iterator yielding elements by value, in reverse
     #[inline]
-    pub fn consume_rev_iter(self) -> InvertIterator<T, ConsumeIterator<T>> {
+    pub fn consume_rev_iter(self) -> InvertIterator<ConsumeIterator<T>> {
         self.consume_iter().invert()
     }
 }
diff --git a/src/libextra/ringbuf.rs b/src/libextra/ringbuf.rs
index f46af664b189..7c940445e77d 100644
--- a/src/libextra/ringbuf.rs
+++ b/src/libextra/ringbuf.rs
@@ -184,7 +184,7 @@ impl<T> RingBuf<T> {
     }
 
     /// Back-to-front iterator.
-    pub fn rev_iter<'a>(&'a self) -> InvertIterator<&'a T, RingBufIterator<'a, T>> {
+    pub fn rev_iter<'a>(&'a self) -> InvertIterator<RingBufIterator<'a, T>> {
         self.iter().invert()
     }
 
@@ -195,7 +195,7 @@ impl<T> RingBuf<T> {
     }
 
     /// Back-to-front iterator which returns mutable values.
-    pub fn mut_rev_iter<'a>(&'a mut self) -> InvertIterator<&'a mut T, RingBufMutIterator<'a, T>> {
+    pub fn mut_rev_iter<'a>(&'a mut self) -> InvertIterator<RingBufMutIterator<'a, T>> {
         self.mut_iter().invert()
     }
 }
diff --git a/src/libextra/smallintmap.rs b/src/libextra/smallintmap.rs
index bd78f41ddf51..d292ff256c45 100644
--- a/src/libextra/smallintmap.rs
+++ b/src/libextra/smallintmap.rs
@@ -207,7 +207,7 @@ impl<V> SmallIntMap<V> {
     /// Empties the hash map, moving all values into the specified closure
     pub fn consume(&mut self)
         -> FilterMapIterator<(uint, Option<V>), (uint, V),
-                EnumerateIterator<Option<V>, VecConsumeIterator<Option<V>>>>
+                EnumerateIterator<VecConsumeIterator<Option<V>>>>
     {
         let values = replace(&mut self.v, ~[]);
         values.consume_iter().enumerate().filter_map(|(i, v)| {
@@ -293,8 +293,7 @@ pub struct SmallIntMapIterator<'self, T> {
 
 iterator!(impl SmallIntMapIterator -> (uint, &'self T), get_ref)
 double_ended_iterator!(impl SmallIntMapIterator -> (uint, &'self T), get_ref)
-pub type SmallIntMapRevIterator<'self, T> = InvertIterator<(uint, &'self T),
-                                                           SmallIntMapIterator<'self, T>>;
+pub type SmallIntMapRevIterator<'self, T> = InvertIterator<SmallIntMapIterator<'self, T>>;
 
 pub struct SmallIntMapMutIterator<'self, T> {
     priv front: uint,
@@ -304,8 +303,7 @@ pub struct SmallIntMapMutIterator<'self, T> {
 
 iterator!(impl SmallIntMapMutIterator -> (uint, &'self mut T), get_mut_ref)
 double_ended_iterator!(impl SmallIntMapMutIterator -> (uint, &'self mut T), get_mut_ref)
-pub type SmallIntMapMutRevIterator<'self, T> = InvertIterator<(uint, &'self mut T),
-                                                              SmallIntMapMutIterator<'self, T>>;
+pub type SmallIntMapMutRevIterator<'self, T> = InvertIterator<SmallIntMapMutIterator<'self, T>>;
 
 #[cfg(test)]
 mod test_map {
diff --git a/src/libstd/hashmap.rs b/src/libstd/hashmap.rs
index deeda5019422..818c6b69b813 100644
--- a/src/libstd/hashmap.rs
+++ b/src/libstd/hashmap.rs
@@ -770,7 +770,7 @@ impl<T:Hash + Eq> HashSet<T> {
 
     /// Visit the values representing the symmetric difference
     pub fn symmetric_difference_iter<'a>(&'a self, other: &'a HashSet<T>)
-        -> ChainIterator<&'a T, SetAlgebraIter<'a, T>, SetAlgebraIter<'a, T>> {
+        -> ChainIterator<SetAlgebraIter<'a, T>, SetAlgebraIter<'a, T>> {
         self.difference_iter(other).chain_(other.difference_iter(self))
     }
 
@@ -783,7 +783,7 @@ impl<T:Hash + Eq> HashSet<T> {
 
     /// Visit the values representing the union
     pub fn union_iter<'a>(&'a self, other: &'a HashSet<T>)
-        -> ChainIterator<&'a T, HashSetIterator<'a, T>, SetAlgebraIter<'a, T>> {
+        -> ChainIterator<HashSetIterator<'a, T>, SetAlgebraIter<'a, T>> {
         self.iter().chain_(other.difference_iter(self))
     }
 
diff --git a/src/libstd/iterator.rs b/src/libstd/iterator.rs
index d3b2325fd9dd..a6460935a503 100644
--- a/src/libstd/iterator.rs
+++ b/src/libstd/iterator.rs
@@ -66,37 +66,36 @@ pub trait RandomAccessIterator<A>: Iterator<A> {
 /// Iterator adaptors provided for every `DoubleEndedIterator` implementation.
 ///
 /// In the future these will be default methods instead of a utility trait.
-pub trait DoubleEndedIteratorUtil<A> {
+pub trait DoubleEndedIteratorUtil {
     /// Flip the direction of the iterator
-    fn invert(self) -> InvertIterator<A, Self>;
+    fn invert(self) -> InvertIterator<Self>;
 }
 
 /// Iterator adaptors provided for every `DoubleEndedIterator` implementation.
 ///
 /// In the future these will be default methods instead of a utility trait.
-impl<A, T: DoubleEndedIterator<A>> DoubleEndedIteratorUtil<A> for T {
+impl<A, T: DoubleEndedIterator<A>> DoubleEndedIteratorUtil for T {
     /// Flip the direction of the iterator
     #[inline]
-    fn invert(self) -> InvertIterator<A, T> {
+    fn invert(self) -> InvertIterator<T> {
         InvertIterator{iter: self}
     }
 }
 
 /// An double-ended iterator with the direction inverted
-// FIXME #6967: Dummy A parameter to get around type inference bug
 #[deriving(Clone)]
-pub struct InvertIterator<A, T> {
+pub struct InvertIterator<T> {
     priv iter: T
 }
 
-impl<A, T: DoubleEndedIterator<A>> Iterator<A> for InvertIterator<A, T> {
+impl<A, T: DoubleEndedIterator<A>> Iterator<A> for InvertIterator<T> {
     #[inline]
     fn next(&mut self) -> Option<A> { self.iter.next_back() }
     #[inline]
     fn size_hint(&self) -> (uint, Option<uint>) { self.iter.size_hint() }
 }
 
-impl<A, T: DoubleEndedIterator<A>> DoubleEndedIterator<A> for InvertIterator<A, T> {
+impl<A, T: DoubleEndedIterator<A>> DoubleEndedIterator<A> for InvertIterator<T> {
     #[inline]
     fn next_back(&mut self) -> Option<A> { self.iter.next() }
 }
@@ -120,7 +119,7 @@ pub trait IteratorUtil<A> {
     /// assert_eq!(it.next().get(), &1);
     /// assert!(it.next().is_none());
     /// ~~~
-    fn chain_<U: Iterator<A>>(self, other: U) -> ChainIterator<A, Self, U>;
+    fn chain_<U: Iterator<A>>(self, other: U) -> ChainIterator<Self, U>;
 
     /// Creates an iterator which iterates over both this and the specified
     /// iterators simultaneously, yielding the two elements as pairs. When
@@ -136,7 +135,7 @@ pub trait IteratorUtil<A> {
     /// assert_eq!(it.next().get(), (&0, &1));
     /// assert!(it.next().is_none());
     /// ~~~
-    fn zip<B, U: Iterator<B>>(self, other: U) -> ZipIterator<A, Self, B, U>;
+    fn zip<B, U: Iterator<B>>(self, other: U) -> ZipIterator<Self, U>;
 
     // FIXME: #5898: should be called map
     /// Creates a new iterator which will apply the specified function to each
@@ -193,7 +192,7 @@ pub trait IteratorUtil<A> {
     /// assert_eq!(it.next().get(), (1, &200));
     /// assert!(it.next().is_none());
     /// ~~~
-    fn enumerate(self) -> EnumerateIterator<A, Self>;
+    fn enumerate(self) -> EnumerateIterator<Self>;
 
     /// Creates an iterator which invokes the predicate on elements until it
     /// returns false. Once the predicate returns false, all further elements are
@@ -238,7 +237,7 @@ pub trait IteratorUtil<A> {
     /// assert_eq!(it.next().get(), &5);
     /// assert!(it.next().is_none());
     /// ~~~
-    fn skip(self, n: uint) -> SkipIterator<A, Self>;
+    fn skip(self, n: uint) -> SkipIterator<Self>;
 
     // FIXME: #5898: should be called take
     /// Creates an iterator which yields the first `n` elements of this
@@ -254,7 +253,7 @@ pub trait IteratorUtil<A> {
     /// assert_eq!(it.next().get(), &3);
     /// assert!(it.next().is_none());
     /// ~~~
-    fn take_(self, n: uint) -> TakeIterator<A, Self>;
+    fn take_(self, n: uint) -> TakeIterator<Self>;
 
     /// Creates a new iterator which behaves in a similar fashion to foldl.
     /// There is a state which is passed between each iteration and can be
@@ -297,7 +296,7 @@ pub trait IteratorUtil<A> {
     /// ~~~
     // FIXME: #5898: should be called `flat_map`
     fn flat_map_<'r, B, U: Iterator<B>>(self, f: &'r fn(A) -> U)
-        -> FlatMapIterator<'r, A, B, Self, U>;
+        -> FlatMapIterator<'r, A, Self, U>;
 
     /// Creates an iterator that calls a function with a reference to each
     /// element before yielding it. This is often useful for debugging an
@@ -464,12 +463,12 @@ pub trait IteratorUtil<A> {
 /// In the future these will be default methods instead of a utility trait.
 impl<A, T: Iterator<A>> IteratorUtil<A> for T {
     #[inline]
-    fn chain_<U: Iterator<A>>(self, other: U) -> ChainIterator<A, T, U> {
+    fn chain_<U: Iterator<A>>(self, other: U) -> ChainIterator<T, U> {
         ChainIterator{a: self, b: other, flag: false}
     }
 
     #[inline]
-    fn zip<B, U: Iterator<B>>(self, other: U) -> ZipIterator<A, T, B, U> {
+    fn zip<B, U: Iterator<B>>(self, other: U) -> ZipIterator<T, U> {
         ZipIterator{a: self, b: other}
     }
 
@@ -490,7 +489,7 @@ impl<A, T: Iterator<A>> IteratorUtil<A> for T {
     }
 
     #[inline]
-    fn enumerate(self) -> EnumerateIterator<A, T> {
+    fn enumerate(self) -> EnumerateIterator<T> {
         EnumerateIterator{iter: self, count: 0}
     }
 
@@ -505,13 +504,13 @@ impl<A, T: Iterator<A>> IteratorUtil<A> for T {
     }
 
     #[inline]
-    fn skip(self, n: uint) -> SkipIterator<A, T> {
+    fn skip(self, n: uint) -> SkipIterator<T> {
         SkipIterator{iter: self, n: n}
     }
 
     // FIXME: #5898: should be called take
     #[inline]
-    fn take_(self, n: uint) -> TakeIterator<A, T> {
+    fn take_(self, n: uint) -> TakeIterator<T> {
         TakeIterator{iter: self, n: n}
     }
 
@@ -523,7 +522,7 @@ impl<A, T: Iterator<A>> IteratorUtil<A> for T {
 
     #[inline]
     fn flat_map_<'r, B, U: Iterator<B>>(self, f: &'r fn(A) -> U)
-        -> FlatMapIterator<'r, A, B, T, U> {
+        -> FlatMapIterator<'r, A, T, U> {
         FlatMapIterator{iter: self, f: f, subiter: None }
     }
 
@@ -758,8 +757,7 @@ impl<A: Ord, T: Iterator<A>> OrdIterator<A> for T {
 }
 
 /// A trait for iterators that are clonable.
-// FIXME #6967: Dummy A parameter to get around type inference bug
-pub trait ClonableIterator<A> {
+pub trait ClonableIterator {
     /// Repeats an iterator endlessly
     ///
     /// # Example
@@ -770,24 +768,24 @@ pub trait ClonableIterator<A> {
     /// assert_eq!(cy.next(), Some(1));
     /// assert_eq!(cy.next(), Some(1));
     /// ~~~
-    fn cycle(self) -> CycleIterator<A, Self>;
+    fn cycle(self) -> CycleIterator<Self>;
 }
 
-impl<A, T: Clone + Iterator<A>> ClonableIterator<A> for T {
+impl<A, T: Clone + Iterator<A>> ClonableIterator for T {
     #[inline]
-    fn cycle(self) -> CycleIterator<A, T> {
+    fn cycle(self) -> CycleIterator<T> {
         CycleIterator{orig: self.clone(), iter: self}
     }
 }
 
 /// An iterator that repeats endlessly
 #[deriving(Clone)]
-pub struct CycleIterator<A, T> {
+pub struct CycleIterator<T> {
     priv orig: T,
     priv iter: T,
 }
 
-impl<A, T: Clone + Iterator<A>> Iterator<A> for CycleIterator<A, T> {
+impl<A, T: Clone + Iterator<A>> Iterator<A> for CycleIterator<T> {
     #[inline]
     fn next(&mut self) -> Option<A> {
         match self.iter.next() {
@@ -808,15 +806,14 @@ impl<A, T: Clone + Iterator<A>> Iterator<A> for CycleIterator<A, T> {
 }
 
 /// An iterator which strings two iterators together
-// FIXME #6967: Dummy A parameter to get around type inference bug
 #[deriving(Clone)]
-pub struct ChainIterator<A, T, U> {
+pub struct ChainIterator<T, U> {
     priv a: T,
     priv b: U,
     priv flag: bool
 }
 
-impl<A, T: Iterator<A>, U: Iterator<A>> Iterator<A> for ChainIterator<A, T, U> {
+impl<A, T: Iterator<A>, U: Iterator<A>> Iterator<A> for ChainIterator<T, U> {
     #[inline]
     fn next(&mut self) -> Option<A> {
         if self.flag {
@@ -853,7 +850,7 @@ impl<A, T: Iterator<A>, U: Iterator<A>> Iterator<A> for ChainIterator<A, T, U> {
 }
 
 impl<A, T: DoubleEndedIterator<A>, U: DoubleEndedIterator<A>> DoubleEndedIterator<A>
-for ChainIterator<A, T, U> {
+for ChainIterator<T, U> {
     #[inline]
     fn next_back(&mut self) -> Option<A> {
         match self.b.next_back() {
@@ -864,7 +861,7 @@ for ChainIterator<A, T, U> {
 }
 
 impl<A, T: RandomAccessIterator<A>, U: RandomAccessIterator<A>> RandomAccessIterator<A>
-for ChainIterator<A, T, U> {
+for ChainIterator<T, U> {
     #[inline]
     fn indexable(&self) -> uint {
         let (a, b) = (self.a.indexable(), self.b.indexable());
@@ -888,14 +885,13 @@ for ChainIterator<A, T, U> {
 }
 
 /// An iterator which iterates two other iterators simultaneously
-// FIXME #6967: Dummy A & B parameters to get around type inference bug
 #[deriving(Clone)]
-pub struct ZipIterator<A, T, B, U> {
+pub struct ZipIterator<T, U> {
     priv a: T,
     priv b: U
 }
 
-impl<A, B, T: Iterator<A>, U: Iterator<B>> Iterator<(A, B)> for ZipIterator<A, T, B, U> {
+impl<A, B, T: Iterator<A>, U: Iterator<B>> Iterator<(A, B)> for ZipIterator<T, U> {
     #[inline]
     fn next(&mut self) -> Option<(A, B)> {
         match (self.a.next(), self.b.next()) {
@@ -1042,14 +1038,13 @@ for FilterMapIterator<'self, A, B, T> {
 }
 
 /// An iterator which yields the current count and the element during iteration
-// FIXME #6967: Dummy A parameter to get around type inference bug
 #[deriving(Clone)]
-pub struct EnumerateIterator<A, T> {
+pub struct EnumerateIterator<T> {
     priv iter: T,
     priv count: uint
 }
 
-impl<A, T: Iterator<A>> Iterator<(uint, A)> for EnumerateIterator<A, T> {
+impl<A, T: Iterator<A>> Iterator<(uint, A)> for EnumerateIterator<T> {
     #[inline]
     fn next(&mut self) -> Option<(uint, A)> {
         match self.iter.next() {
@@ -1141,14 +1136,13 @@ impl<'self, A, T: Iterator<A>> Iterator<A> for TakeWhileIterator<'self, A, T> {
 }
 
 /// An iterator which skips over `n` elements of `iter`.
-// FIXME #6967: Dummy A parameter to get around type inference bug
 #[deriving(Clone)]
-pub struct SkipIterator<A, T> {
+pub struct SkipIterator<T> {
     priv iter: T,
     priv n: uint
 }
 
-impl<A, T: Iterator<A>> Iterator<A> for SkipIterator<A, T> {
+impl<A, T: Iterator<A>> Iterator<A> for SkipIterator<T> {
     #[inline]
     fn next(&mut self) -> Option<A> {
         let mut next = self.iter.next();
@@ -1190,14 +1184,13 @@ impl<A, T: Iterator<A>> Iterator<A> for SkipIterator<A, T> {
 }
 
 /// An iterator which only iterates over the first `n` iterations of `iter`.
-// FIXME #6967: Dummy A parameter to get around type inference bug
 #[deriving(Clone)]
-pub struct TakeIterator<A, T> {
+pub struct TakeIterator<T> {
     priv iter: T,
     priv n: uint
 }
 
-impl<A, T: Iterator<A>> Iterator<A> for TakeIterator<A, T> {
+impl<A, T: Iterator<A>> Iterator<A> for TakeIterator<T> {
     #[inline]
     fn next(&mut self) -> Option<A> {
         let next = self.iter.next();
@@ -1249,15 +1242,14 @@ impl<'self, A, B, T: Iterator<A>, St> Iterator<B> for ScanIterator<'self, A, B,
 /// An iterator that maps each element to an iterator,
 /// and yields the elements of the produced iterators
 ///
-// FIXME #6967: Dummy B parameter to get around type inference bug
-pub struct FlatMapIterator<'self, A, B, T, U> {
+pub struct FlatMapIterator<'self, A, T, U> {
     priv iter: T,
     priv f: &'self fn(A) -> U,
     priv subiter: Option<U>,
 }
 
 impl<'self, A, T: Iterator<A>, B, U: Iterator<B>> Iterator<B> for
-    FlatMapIterator<'self, A, B, T, U> {
+    FlatMapIterator<'self, A, T, U> {
     #[inline]
     fn next(&mut self) -> Option<B> {
         loop {
diff --git a/src/libstd/vec.rs b/src/libstd/vec.rs
index 8dbae43689d5..30f2b6924528 100644
--- a/src/libstd/vec.rs
+++ b/src/libstd/vec.rs
@@ -2168,7 +2168,7 @@ pub struct VecIterator<'self, T> {
 iterator!{impl VecIterator -> &'self T}
 double_ended_iterator!{impl VecIterator -> &'self T}
 random_access_iterator!{impl VecIterator -> &'self T}
-pub type VecRevIterator<'self, T> = InvertIterator<&'self T, VecIterator<'self, T>>;
+pub type VecRevIterator<'self, T> = InvertIterator<VecIterator<'self, T>>;
 
 impl<'self, T> Clone for VecIterator<'self, T> {
     fn clone(&self) -> VecIterator<'self, T> { *self }
@@ -2184,7 +2184,7 @@ pub struct VecMutIterator<'self, T> {
 iterator!{impl VecMutIterator -> &'self mut T}
 double_ended_iterator!{impl VecMutIterator -> &'self mut T}
 random_access_iterator!{impl VecMutIterator -> &'self mut T}
-pub type VecMutRevIterator<'self, T> = InvertIterator<&'self mut T, VecMutIterator<'self, T>>;
+pub type VecMutRevIterator<'self, T> = InvertIterator<VecMutIterator<'self, T>>;
 
 /// An iterator that moves out of a vector.
 #[deriving(Clone)]