1 files changed, 7 insertions, 0 deletions
diff --git a/compiler/rustc_index/src/vec.rs b/compiler/rustc_index/src/vec.rs
index 4172ce3bb..39aa27a23 100644
--- a/compiler/rustc_index/src/vec.rs
+++ b/compiler/rustc_index/src/vec.rs
@@ -1,3 +1,4 @@
+#[cfg(feature = "rustc_serialize")]
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 
 use std::fmt;
@@ -17,10 +18,12 @@ pub trait Idx: Copy + 'static + Eq + PartialEq + Debug + Hash {
 
     fn index(self) -> usize;
 
+    #[inline]
     fn increment_by(&mut self, amount: usize) {
         *self = self.plus(amount);
     }
 
+    #[inline]
     fn plus(self, amount: usize) -> Self {
         Self::new(self.index() + amount)
     }
@@ -59,12 +62,14 @@ pub struct IndexVec<I: Idx, T> {
 // 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 }
@@ -357,11 +362,13 @@ impl<I: Idx, T> Extend<T> for IndexVec<I, T> {
     }
 
     #[inline]
+    #[cfg(feature = "nightly")]
     fn extend_one(&mut self, item: T) {
         self.raw.push(item);
     }
 
     #[inline]
+    #[cfg(feature = "nightly")]
     fn extend_reserve(&mut self, additional: usize) {
         self.raw.reserve(additional);
     }