diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 5c6045e6..5a672a03 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -2,7 +2,7 @@
 
 #[cfg(feature = "std")]
 use std::borrow::Cow;
-#[cfg(all(feature = "unstable", feature = "collections", not(feature = "std")))]
+#[cfg(all(feature = "collections", not(feature = "std")))]
 use collections::borrow::Cow;
 
 #[cfg(all(feature = "collections", not(feature = "std")))]
@@ -27,12 +27,13 @@ use std::collections::{
     VecDeque,
 };
 
-#[cfg(all(feature = "unstable", feature = "collections"))]
+#[cfg(feature = "collections")]
 use collections::enum_set::{CLike, EnumSet};
-#[cfg(all(feature = "unstable", feature = "collections"))]
+#[cfg(feature = "collections")]
 use collections::borrow::ToOwned;
 
 use core::fmt;
+#[cfg(feature = "std")]
 use core::hash::{Hash, BuildHasher};
 use core::marker::PhantomData;
 #[cfg(feature = "std")]
@@ -43,15 +44,15 @@ use core::str;
 
 #[cfg(feature = "std")]
 use std::rc::Rc;
-#[cfg(all(feature = "unstable", feature = "alloc", not(feature = "std")))]
+#[cfg(all(feature = "alloc", not(feature = "std")))]
 use alloc::rc::Rc;
 
 #[cfg(feature = "std")]
 use std::sync::Arc;
-#[cfg(all(feature = "unstable", feature = "alloc", not(feature = "std")))]
+#[cfg(all(feature = "alloc", not(feature = "std")))]
 use alloc::arc::Arc;
 
-#[cfg(all(feature = "unstable", feature = "alloc", not(feature = "std")))]
+#[cfg(all(feature = "alloc", not(feature = "std")))]
 use alloc::boxed::Box;
 
 #[cfg(feature = "std")]
@@ -482,7 +483,7 @@ seq_impl!(
     BTreeSet::new(),
     BTreeSet::insert);
 
-#[cfg(all(feature = "unstable", feature = "collections"))]
+#[cfg(feature = "collections")]
 seq_impl!(
     EnumSet<T>,
     EnumSetVisitor<T: Deserialize + CLike>,
diff --git a/serde/src/de/mod.rs b/serde/src/de/mod.rs
index 967af350..3a51ead5 100644
--- a/serde/src/de/mod.rs
+++ b/serde/src/de/mod.rs
@@ -415,7 +415,7 @@ pub trait Deserialize: Sized {
 /// to deserialize it into a flat representation like `vec![1, 2, 3, 4, 5, 6]`.
 /// Allocating a brand new `Vec<T>` for each subarray would be slow. Instead we
 /// would like to allocate a single `Vec<T>` and then deserialize each subarray
-/// into it. This requires stateful deserialization using the DeserializeSeed
+/// into it. This requires stateful deserialization using the `DeserializeSeed`
 /// trait.
 ///
 /// ```rust
diff --git a/serde/src/de/value.rs b/serde/src/de/value.rs
index f34fb087..71bb353b 100644
--- a/serde/src/de/value.rs
+++ b/serde/src/de/value.rs
@@ -33,9 +33,7 @@ use collections::boxed::Box;
 #[cfg(all(feature = "collections", not(feature = "std")))]
 use collections::string::ToString;
 
-#[cfg(all(feature = "unstable", feature = "collections"))]
-use collections::borrow::ToOwned;
-
+#[cfg(feature = "std")]
 use core::hash::Hash;
 #[cfg(feature = "std")]
 use std::error;
@@ -67,7 +65,7 @@ impl de::Error for Error {
     }
 
     #[cfg(not(any(feature = "std", feature = "collections")))]
-    fn custom<T: Display>(msg: T) -> Self {
+    fn custom<T: Display>(_msg: T) -> Self {
         Error(())
     }
 }
@@ -579,7 +577,7 @@ impl<I, E> MapDeserializer<I, E>
         }
     }
 
-    fn next(&mut self) -> Option<(<I::Item as private::Pair>::First, <I::Item as private::Pair>::Second)> {
+    fn next_pair(&mut self) -> Option<(<I::Item as private::Pair>::First, <I::Item as private::Pair>::Second)> {
         match self.iter.next() {
             Some(kv) => {
                 self.count += 1;
@@ -654,7 +652,7 @@ impl<I, E> de::MapVisitor for MapDeserializer<I, E>
     fn visit_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
         where T: de::DeserializeSeed,
     {
-        match self.next() {
+        match self.next_pair() {
             Some((key, value)) => {
                 self.value = Some(value);
                 seed.deserialize(key.into_deserializer()).map(Some)
@@ -677,7 +675,7 @@ impl<I, E> de::MapVisitor for MapDeserializer<I, E>
         where TK: de::DeserializeSeed,
               TV: de::DeserializeSeed
     {
-        match self.next() {
+        match self.next_pair() {
             Some((key, value)) => {
                 let key = try!(kseed.deserialize(key.into_deserializer()));
                 let value = try!(vseed.deserialize(value.into_deserializer()));
@@ -704,7 +702,7 @@ impl<I, E> de::SeqVisitor for MapDeserializer<I, E>
     fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
         where T: de::DeserializeSeed,
     {
-        match self.next() {
+        match self.next_pair() {
             Some((k, v)) => {
                 let de = PairDeserializer(k, v, PhantomData);
                 seed.deserialize(de).map(Some)
@@ -993,8 +991,8 @@ mod private {
         }
     }
 
-    /// Avoid having to restate the generic types on MapDeserializer. The
-    /// Iterator::Item contains enough information to figure out K and V.
+    /// Avoid having to restate the generic types on `MapDeserializer`. The
+    /// `Iterator::Item` contains enough information to figure out K and V.
     pub trait Pair {
         type First;
         type Second;
diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index 24f2a677..093fa286 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -11,30 +11,29 @@
 
 #![doc(html_root_url="https://docs.serde.rs")]
 #![cfg_attr(not(feature = "std"), no_std)]
-#![cfg_attr(feature = "unstable", feature(reflect_marker, unicode, nonzero, plugin, step_trait, zero_one, inclusive_range))]
+#![cfg_attr(feature = "unstable", feature(nonzero, inclusive_range, zero_one))]
 #![cfg_attr(feature = "alloc", feature(alloc))]
 #![cfg_attr(feature = "collections", feature(collections, enumset))]
+#![cfg_attr(feature = "clippy", feature(plugin))]
 #![cfg_attr(feature = "clippy", plugin(clippy))]
-#![cfg_attr(feature = "clippy", allow(linkedlist))]
-
-#![cfg_attr(any(not(feature = "std"), feature = "unstable"), allow(unused_variables, unused_imports, unused_features, dead_code))]
-
+#![cfg_attr(feature = "clippy", allow(linkedlist, type_complexity))]
 #![deny(missing_docs)]
 
-#[cfg(all(feature = "unstable", feature = "collections"))]
+#[cfg(feature = "collections")]
 extern crate collections;
 
-#[cfg(all(feature = "unstable", feature = "alloc"))]
+#[cfg(feature = "alloc")]
 extern crate alloc;
 
+#[cfg(feature = "unstable")]
+extern crate core as actual_core;
+
 #[cfg(feature = "std")]
 mod core {
     pub use std::{ops, hash, fmt, cmp, marker, mem, i8, i16, i32, i64, u8, u16, u32, u64, isize,
             usize, f32, f64, char, str, num, slice, iter, cell};
     #[cfg(feature = "unstable")]
-    extern crate core;
-    #[cfg(feature = "unstable")]
-    pub use self::core::nonzero;
+    pub use actual_core::nonzero;
 }
 
 pub use ser::{Serialize, Serializer};
@@ -48,6 +47,6 @@ pub mod de;
 #[cfg(feature = "std")]
 pub mod iter;
 pub mod ser;
-#[cfg(not(feature = "std"))]
+#[cfg_attr(feature = "std", doc(hidden))]
 pub mod error;
 mod utils;
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index e89f0cd3..25789356 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -30,19 +30,18 @@ use collections::{
     Vec,
 };
 
-#[cfg(all(feature = "unstable", feature = "collections"))]
+#[cfg(feature = "collections")]
 use collections::enum_set::{CLike, EnumSet};
-#[cfg(all(feature = "unstable", feature = "collections"))]
+#[cfg(feature = "collections")]
 use collections::borrow::ToOwned;
 
+#[cfg(feature = "std")]
 use core::hash::{Hash, BuildHasher};
 #[cfg(feature = "unstable")]
 use core::iter;
 #[cfg(feature = "std")]
 use std::net;
 #[cfg(feature = "unstable")]
-use core::num;
-#[cfg(feature = "unstable")]
 use core::ops;
 #[cfg(feature = "std")]
 use std::path;
@@ -67,14 +66,13 @@ use core::marker::PhantomData;
 use core::nonzero::{NonZero, Zeroable};
 
 use super::{
-    Error,
     Serialize,
-    SerializeMap,
     SerializeSeq,
-    SerializeStruct,
     SerializeTuple,
     Serializer,
 };
+#[cfg(any(feature = "std", feature = "unstable"))]
+use super::Error;
 
 #[cfg(feature = "unstable")]
 use super::Iterator;
@@ -241,7 +239,7 @@ impl<'a, I> Serialize for Iterator<I>
         // FIXME: use specialization to prevent invalidating the object in case of clonable iterators?
         let iter = match self.0.borrow_mut().take() {
             Some(iter) => iter.into_iter(),
-            None => return Err(S::Error::custom("Iterator used twice")),
+            None => return Err(Error::custom("Iterator used twice")),
         };
         let size = match iter.size_hint() {
             (lo, Some(hi)) if lo == hi => Some(lo),
@@ -286,7 +284,7 @@ impl<T> Serialize for BTreeSet<T>
     serialize_seq!();
 }
 
-#[cfg(all(feature = "unstable", feature = "collections"))]
+#[cfg(feature = "collections")]
 impl<T> Serialize for EnumSet<T>
     where T: Serialize + CLike
 {
@@ -573,6 +571,7 @@ macro_rules! serialize_map {
         fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
             where S: Serializer,
         {
+            use super::SerializeMap;
             let mut map = try!(serializer.serialize_map(Some(self.len())));
             for (k, v) in self {
                 try!(map.serialize_key(k));
@@ -695,6 +694,7 @@ impl Serialize for Duration {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
         where S: Serializer,
     {
+        use super::SerializeStruct;
         let mut state = try!(serializer.serialize_struct("Duration", 2));
         try!(state.serialize_field("secs", self.as_secs()));
         try!(state.serialize_field("nanos", self.subsec_nanos()));
diff --git a/serde/src/ser/mod.rs b/serde/src/ser/mod.rs
index 10b14fda..4131f0b2 100644
--- a/serde/src/ser/mod.rs
+++ b/serde/src/ser/mod.rs
@@ -15,11 +15,6 @@ use std::error;
 #[cfg(not(feature = "std"))]
 use error;
 
-#[cfg(all(feature = "collections", not(feature = "std")))]
-use collections::String;
-
-#[cfg(feature = "unstable")]
-use core::marker::PhantomData;
 #[cfg(feature = "unstable")]
 use core::cell::RefCell;