Fix clippy recommendations and compiler warnings

src/ser/key.rs

@@ -38,7 +38,7 @@ where
     End: for<'key> FnOnce(Key<'key>) -> Result<Ok, Error>,
 {
     pub fn new(end: End) -> Self {
-        KeySink { end: end }
+        KeySink { end }
     }
 }
 

src/ser/mod.rs

@@ -50,7 +50,7 @@ impl<'input, 'output, Target: 'output + UrlEncodedTarget> Serializer<'input, 'ou
     /// Returns a new `Serializer`.
     pub fn new(urlencoder: &'output mut UrlEncodedSerializer<'input, Target>) -> Self {
         Serializer {
-            urlencoder: urlencoder,
+            urlencoder,
         }
     }
 }
@@ -72,6 +72,7 @@ impl fmt::Display for Error {
 }
 
 impl error::Error for Error {
+    #[allow(deprecated)]
     fn description(&self) -> &str {
         match *self {
             Error::Custom(ref msg) => msg,
@@ -80,7 +81,7 @@ impl error::Error for Error {
     }
 
     /// The lower-level cause of this error, in the case of a `Utf8` error.
-    fn cause(&self) -> Option<&error::Error> {
+    fn cause(&self) -> Option<&dyn error::Error> {
         match *self {
             Error::Custom(_) => None,
             Error::Utf8(ref err) => Some(err),
@@ -478,7 +479,7 @@ where
         value: &T,
     ) -> Result<(), Error> {
         {
-            let key = self.key.as_ref().ok_or_else(|| Error::no_key())?;
+            let key = self.key.as_ref().ok_or_else(Error::no_key)?;
             let value_sink = value::ValueSink::new(self.urlencoder, &key);
             value.serialize(part::PartSerializer::new(value_sink))?;
         }

src/ser/pair.rs

@@ -19,7 +19,7 @@ where
 {
     pub fn new(urlencoder: &'target mut UrlEncodedSerializer<'input, Target>) -> Self {
         PairSerializer {
-            urlencoder: urlencoder,
+            urlencoder,
             state: PairState::WaitingForKey,
         }
     }
@@ -229,7 +229,7 @@ where
                 if result.is_ok() {
                     self.state = PairState::Done;
                 } else {
-                    self.state = PairState::WaitingForValue { key: key };
+                    self.state = PairState::WaitingForValue { key };
                 }
                 result
             },

src/ser/part.rs

@@ -10,7 +10,7 @@ pub struct PartSerializer<S> {
 
 impl<S: Sink> PartSerializer<S> {
     pub fn new(sink: S) -> Self {
-        PartSerializer { sink: sink }
+        PartSerializer { sink }
     }
 }
 
@@ -110,7 +110,7 @@ impl<S: Sink> ser::Serializer for PartSerializer<S> {
     }
 
     fn serialize_unit_struct(self, name: &'static str) -> Result<S::Ok, Error> {
-        self.sink.serialize_static_str(name.into())
+        self.sink.serialize_static_str(name)
     }
 
     fn serialize_unit_variant(
@@ -119,7 +119,7 @@ impl<S: Sink> ser::Serializer for PartSerializer<S> {
         _variant_index: u32,
         variant: &'static str,
     ) -> Result<S::Ok, Error> {
-        self.sink.serialize_static_str(variant.into())
+        self.sink.serialize_static_str(variant)
     }
 
     fn serialize_newtype_struct<T: ?Sized + ser::Serialize>(

src/ser/value.rs

@@ -22,8 +22,8 @@ where
         key: &'key str,
     ) -> Self {
         ValueSink {
-            urlencoder: urlencoder,
-            key: key,
+            urlencoder,
+            key,
         }
     }
 }