Merge branch 'v0.6.x' into master

# Conflicts:
#	serde/Cargo.toml
#	serde/src/ser/impls.rs
#	serde_codegen/src/attr.rs
#	serde_codegen/src/de.rs
#	serde_codegen/src/field.rs
#	serde_codegen/src/ser.rs

serde/Cargo.toml

@@ -9,13 +9,13 @@ documentation = "https://serde-rs.github.io/serde/serde/serde/index.html"
 readme = "../README.md"
 keywords = ["serde", "serialization"]
 
-[dependencies.num]
-version = "^0.1.27"
-default-features = false
-
 [features]
-nightly = []
-num-impls = ["num-bigint", "num-complex", "num-rational"]
+nightly = ["clippy"]
 num-bigint = ["num/bigint"]
 num-complex = ["num/complex"]
+num-impls = ["num-bigint", "num-complex", "num-rational"]
 num-rational = ["num/rational"]
+
+[dependencies]
+clippy = { version = "^0.0.35", optional = true }
+num = { version = "^0.1.27", default-features = false }

serde/src/de/impls.rs

@@ -234,7 +234,7 @@ impl Visitor for StringVisitor {
     fn visit_str<E>(&mut self, v: &str) -> Result<String, E>
         where E: Error,
     {
-        Ok(v.to_string())
+        Ok(v.to_owned())
     }
 
     fn visit_string<E>(&mut self, v: String) -> Result<String, E>
@@ -247,12 +247,12 @@ impl Visitor for StringVisitor {
         where E: Error,
     {
         match str::from_utf8(v) {
-            Ok(s) => Ok(s.to_string()),
+            Ok(s) => Ok(s.to_owned()),
             Err(_) => Err(Error::type_mismatch(Type::String)),
         }
     }
 
-    fn visit_byte_buf<'a, E>(&mut self, v: Vec<u8>) -> Result<String, E>
+    fn visit_byte_buf<E>(&mut self, v: Vec<u8>) -> Result<String, E>
         where E: Error,
     {
         match String::from_utf8(v) {

serde/src/lib.rs

@@ -10,7 +10,10 @@
 //! [github repository](https://github.com/serde-rs/serde)
 
 #![doc(html_root_url="https://serde-rs.github.io/serde/serde")]
-#![cfg_attr(feature = "nightly", feature(collections, enumset, nonzero, step_trait, zero_one))]
+#![cfg_attr(feature = "nightly", feature(collections, enumset, nonzero, plugin, step_trait,
+                                         zero_one))]
+#![cfg_attr(feature = "nightly", plugin(clippy))]
+#![cfg_attr(feature = "nightly", allow(linkedlist))]
 
 #![deny(missing_docs)]
 

serde/src/ser/impls.rs

@@ -566,8 +566,8 @@ impl<K, V, I> MapVisitor for MapIteratorVisitor<I>
     {
         match self.iter.next() {
             Some((key, value)) => {
-                let value = try!(serializer.serialize_map_elt(key, value));
-                Ok(Some(value))
+                try!(serializer.serialize_map_elt(key, value));
+                Ok(Some(()))
             }
             None => Ok(None)
         }

serde/src/ser/mod.rs

@@ -322,6 +322,7 @@ pub trait Serializer {
 }
 
 /// A trait that is used by a `Serialize` to iterate through a sequence.
+#[cfg_attr(feature = "nightly", allow(len_without_is_empty))]
 pub trait SeqVisitor {
     /// Serializes a sequence item in the serializer.
     ///
@@ -338,6 +339,7 @@ pub trait SeqVisitor {
 }
 
 /// A trait that is used by a `Serialize` to iterate through a map.
+#[cfg_attr(feature = "nightly", allow(len_without_is_empty))]
 pub trait MapVisitor {
     /// Serializes a map item in the serializer.
     ///