diff --git a/compiler/rustc_index/src/slice.rs b/compiler/rustc_index/src/slice.rs
index cad96ca26bc..8eae079e2f8 100644
--- a/compiler/rustc_index/src/slice.rs
+++ b/compiler/rustc_index/src/slice.rs
@@ -5,7 +5,7 @@
     slice,
 };
 
-use crate::{idx::Idx, vec::IndexVec};
+use crate::{Idx, IndexVec};
 
 /// A view into contiguous `T`s, indexed by `I` rather than by `usize`.
 ///
@@ -140,6 +140,17 @@ pub fn pick3_mut(&mut self, a: I, b: I, c: I) -> (&mut T, &mut T, &mut T) {
         let ptr = self.raw.as_mut_ptr();
         unsafe { (&mut *ptr.add(ai), &mut *ptr.add(bi), &mut *ptr.add(ci)) }
     }
+
+    #[inline]
+    pub fn binary_search(&self, value: &T) -> Result<I, I>
+    where
+        T: Ord,
+    {
+        match self.raw.binary_search(value) {
+            Ok(i) => Ok(Idx::new(i)),
+            Err(i) => Err(Idx::new(i)),
+        }
+    }
 }
 
 impl<I: Idx, J: Idx> IndexSlice<I, J> {
@@ -172,20 +183,6 @@ pub fn invert_bijective_mapping(&self) -> IndexVec<J, I> {
     }
 }
 
-impl<I: Idx, T: Ord> IndexSlice<I, T> {
-    #[inline]
-    pub fn binary_search(&self, value: &T) -> Result<I, I> {
-        match self.raw.binary_search(value) {
-            Ok(i) => Ok(Idx::new(i)),
-            Err(i) => Err(Idx::new(i)),
-        }
-    }
-}
-
-// Whether `IndexSlice` is `Send` depends only on the data,
-// not the phantom data.
-unsafe impl<I: Idx, T> Send for IndexSlice<I, T> where T: Send {}
-
 impl<I: Idx, T: fmt::Debug> fmt::Debug for IndexSlice<I, T> {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::Debug::fmt(&self.raw, fmt)
@@ -208,6 +205,26 @@ fn index_mut(&mut self, index: I) -> &mut T {
     }
 }
 
+impl<'a, I: Idx, T> IntoIterator for &'a IndexSlice<I, T> {
+    type Item = &'a T;
+    type IntoIter = slice::Iter<'a, T>;
+
+    #[inline]
+    fn into_iter(self) -> slice::Iter<'a, T> {
+        self.raw.iter()
+    }
+}
+
+impl<'a, I: Idx, T> IntoIterator for &'a mut IndexSlice<I, T> {
+    type Item = &'a mut T;
+    type IntoIter = slice::IterMut<'a, T>;
+
+    #[inline]
+    fn into_iter(self) -> slice::IterMut<'a, T> {
+        self.raw.iter_mut()
+    }
+}
+
 impl<I: Idx, T: Clone> ToOwned for IndexSlice<I, T> {
     type Owned = IndexVec<I, T>;
 
@@ -234,22 +251,6 @@ fn default() -> Self {
     }
 }
 
-impl<'a, I: Idx, T> IntoIterator for &'a IndexSlice<I, T> {
-    type Item = &'a T;
-    type IntoIter = slice::Iter<'a, T>;
-
-    #[inline]
-    fn into_iter(self) -> slice::Iter<'a, T> {
-        self.raw.iter()
-    }
-}
-
-impl<'a, I: Idx, T> IntoIterator for &'a mut IndexSlice<I, T> {
-    type Item = &'a mut T;
-    type IntoIter = slice::IterMut<'a, T>;
-
-    #[inline]
-    fn into_iter(self) -> slice::IterMut<'a, T> {
-        self.raw.iter_mut()
-    }
-}
+// Whether `IndexSlice` is `Send` depends only on the data,
+// not the phantom data.
+unsafe impl<I: Idx, T> Send for IndexSlice<I, T> where T: Send {}
diff --git a/compiler/rustc_index/src/vec.rs b/compiler/rustc_index/src/vec.rs
index 3cd2eb56936..dce5334461e 100644
--- a/compiler/rustc_index/src/vec.rs
+++ b/compiler/rustc_index/src/vec.rs
@@ -9,8 +9,7 @@
 use std::slice;
 use std::vec;
 
-use crate::idx::Idx;
-use crate::slice::IndexSlice;
+use crate::{Idx, IndexSlice};
 
 /// An owned contiguous collection of `T`s, indexed by `I` rather than by `usize`.
 ///
@@ -25,30 +24,6 @@ pub struct IndexVec<I: Idx, T> {
     _marker: PhantomData<fn(&I)>,
 }
 
-// Whether `IndexVec` is `Send` depends only on the data,
-// not the phantom data.
-unsafe impl<I: Idx, T> Send for IndexVec<I, T> where T: Send {}
-
-#[cfg(feature = "rustc_serialize")]
-impl<S: Encoder, I: Idx, T: Encodable<S>> Encodable<S> for IndexVec<I, T> {
-    fn encode(&self, s: &mut S) {
-        Encodable::encode(&self.raw, s);
-    }
-}
-
-#[cfg(feature = "rustc_serialize")]
-impl<D: Decoder, I: Idx, T: Decodable<D>> Decodable<D> for IndexVec<I, T> {
-    fn decode(d: &mut D) -> Self {
-        IndexVec { raw: Decodable::decode(d), _marker: PhantomData }
-    }
-}
-
-impl<I: Idx, T: fmt::Debug> fmt::Debug for IndexVec<I, T> {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(&self.raw, fmt)
-    }
-}
-
 impl<I: Idx, T> IndexVec<I, T> {
     #[inline]
     pub fn new() -> Self {
@@ -183,6 +158,14 @@ pub fn ensure_contains_elem(&mut self, elem: I, fill_value: impl FnMut() -> T) -
         &mut self[elem]
     }
 
+    #[inline]
+    pub fn resize(&mut self, new_len: usize, value: T)
+    where
+        T: Clone,
+    {
+        self.raw.resize(new_len, value)
+    }
+
     #[inline]
     pub fn resize_to_elem(&mut self, elem: I, fill_value: impl FnMut() -> T) {
         let min_new_len = elem.index() + 1;
@@ -190,6 +173,30 @@ pub fn resize_to_elem(&mut self, elem: I, fill_value: impl FnMut() -> T) {
     }
 }
 
+/// `IndexVec` is often used as a map, so it provides some map-like APIs.
+impl<I: Idx, T> IndexVec<I, Option<T>> {
+    #[inline]
+    pub fn insert(&mut self, index: I, value: T) -> Option<T> {
+        self.ensure_contains_elem(index, || None).replace(value)
+    }
+
+    #[inline]
+    pub fn get_or_insert_with(&mut self, index: I, value: impl FnOnce() -> T) -> &mut T {
+        self.ensure_contains_elem(index, || None).get_or_insert_with(value)
+    }
+
+    #[inline]
+    pub fn remove(&mut self, index: I) -> Option<T> {
+        self.get_mut(index)?.take()
+    }
+}
+
+impl<I: Idx, T: fmt::Debug> fmt::Debug for IndexVec<I, T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.raw, fmt)
+    }
+}
+
 impl<I: Idx, T> Deref for IndexVec<I, T> {
     type Target = IndexSlice<I, T>;
 
@@ -218,38 +225,6 @@ fn borrow_mut(&mut self) -> &mut IndexSlice<I, T> {
     }
 }
 
-/// `IndexVec` is often used as a map, so it provides some map-like APIs.
-impl<I: Idx, T> IndexVec<I, Option<T>> {
-    #[inline]
-    pub fn insert(&mut self, index: I, value: T) -> Option<T> {
-        self.ensure_contains_elem(index, || None).replace(value)
-    }
-
-    #[inline]
-    pub fn get_or_insert_with(&mut self, index: I, value: impl FnOnce() -> T) -> &mut T {
-        self.ensure_contains_elem(index, || None).get_or_insert_with(value)
-    }
-
-    #[inline]
-    pub fn remove(&mut self, index: I) -> Option<T> {
-        self.get_mut(index)?.take()
-    }
-}
-
-impl<I: Idx, T: Clone> IndexVec<I, T> {
-    #[inline]
-    pub fn resize(&mut self, new_len: usize, value: T) {
-        self.raw.resize(new_len, value)
-    }
-}
-
-impl<I: Idx, T> Default for IndexVec<I, T> {
-    #[inline]
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
 impl<I: Idx, T> Extend<T> for IndexVec<I, T> {
     #[inline]
     fn extend<J: IntoIterator<Item = T>>(&mut self, iter: J) {
@@ -279,13 +254,6 @@ fn from_iter<J>(iter: J) -> Self
     }
 }
 
-impl<I: Idx, T, const N: usize> From<[T; N]> for IndexVec<I, T> {
-    #[inline]
-    fn from(array: [T; N]) -> Self {
-        IndexVec::from_raw(array.into())
-    }
-}
-
 impl<I: Idx, T> IntoIterator for IndexVec<I, T> {
     type Item = T;
     type IntoIter = vec::IntoIter<T>;
@@ -316,5 +284,37 @@ fn into_iter(self) -> slice::IterMut<'a, T> {
     }
 }
 
+impl<I: Idx, T> Default for IndexVec<I, T> {
+    #[inline]
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<I: Idx, T, const N: usize> From<[T; N]> for IndexVec<I, T> {
+    #[inline]
+    fn from(array: [T; N]) -> Self {
+        IndexVec::from_raw(array.into())
+    }
+}
+
+#[cfg(feature = "rustc_serialize")]
+impl<S: Encoder, I: Idx, T: Encodable<S>> Encodable<S> for IndexVec<I, T> {
+    fn encode(&self, s: &mut S) {
+        Encodable::encode(&self.raw, s);
+    }
+}
+
+#[cfg(feature = "rustc_serialize")]
+impl<D: Decoder, I: Idx, T: Decodable<D>> Decodable<D> for IndexVec<I, T> {
+    fn decode(d: &mut D) -> Self {
+        IndexVec { raw: Decodable::decode(d), _marker: PhantomData }
+    }
+}
+
+// Whether `IndexVec` is `Send` depends only on the data,
+// not the phantom data.
+unsafe impl<I: Idx, T> Send for IndexVec<I, T> where T: Send {}
+
 #[cfg(test)]
 mod tests;