Release 0.8.7

Fix "variable does not need to be mutable" warning

Fixes #534.

cc @EliDupree

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "0.8.6"
+version = "0.8.7"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "A generic serialization/deserialization framework"

serde/src/bytes.rs

@@ -19,6 +19,15 @@ pub struct Bytes<'a> {
     bytes: &'a [u8],
 }
 
+impl<'a> Bytes<'a> {
+    /// Wrap an existing `&[u8]`.
+    pub fn new(bytes: &'a [u8]) -> Self {
+        Bytes {
+            bytes: bytes,
+        }
+    }
+}
+
 impl<'a> fmt::Debug for Bytes<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         try!(f.write_str("b\""));
@@ -31,18 +40,14 @@ impl<'a> fmt::Debug for Bytes<'a> {
 
 impl<'a> From<&'a [u8]> for Bytes<'a> {
     fn from(bytes: &'a [u8]) -> Self {
-        Bytes {
-            bytes: bytes,
-        }
+        Bytes::new(bytes)
     }
 }
 
 #[cfg(any(feature = "std", feature = "collections"))]
 impl<'a> From<&'a Vec<u8>> for Bytes<'a> {
     fn from(bytes: &'a Vec<u8>) -> Self {
-        Bytes {
-            bytes: bytes,
-        }
+        Bytes::new(bytes)
     }
 }
 
@@ -90,15 +95,18 @@ mod bytebuf {
     impl ByteBuf {
         /// Construct a new, empty `ByteBuf`.
         pub fn new() -> Self {
-            ByteBuf {
-                bytes: Vec::new(),
-            }
+            ByteBuf::from(Vec::new())
         }
 
         /// Construct a new, empty `ByteBuf` with the specified capacity.
         pub fn with_capacity(cap: usize) -> Self {
+            ByteBuf::from(Vec::with_capacity(cap))
+        }
+
+        /// Wrap existing bytes in a `ByteBuf`.
+        pub fn from<T: Into<Vec<u8>>>(bytes: T) -> Self {
             ByteBuf {
-                bytes: Vec::with_capacity(cap)
+                bytes: bytes.into(),
             }
         }
     }
@@ -121,9 +129,7 @@ mod bytebuf {
 
     impl From<Vec<u8>> for ByteBuf {
         fn from(bytes: Vec<u8>) -> Self {
-            ByteBuf {
-                bytes: bytes,
-            }
+            ByteBuf::from(bytes)
         }
     }
 
@@ -179,9 +185,7 @@ mod bytebuf {
         fn visit_unit<E>(&mut self) -> Result<ByteBuf, E>
             where E: de::Error,
         {
-            Ok(ByteBuf {
-                bytes: Vec::new(),
-            })
+            Ok(ByteBuf::new())
         }
 
         #[inline]
@@ -197,9 +201,7 @@ mod bytebuf {
 
             try!(visitor.end());
 
-            Ok(ByteBuf {
-                bytes: values,
-            })
+            Ok(ByteBuf::from(values))
         }
 
         #[inline]
@@ -213,9 +215,7 @@ mod bytebuf {
         fn visit_byte_buf<E>(&mut self, v: Vec<u8>) -> Result<ByteBuf, E>
             where E: de::Error,
         {
-            Ok(ByteBuf {
-                bytes: v,
-            })
+            Ok(ByteBuf::from(v))
         }
     }
 

serde/src/de/mod.rs

@@ -11,71 +11,6 @@ use collections::{String, Vec};
 use core::fmt;
 
 ///////////////////////////////////////////////////////////////////////////////
-/// Macro helper to not have to re-implement all the defaulted methods.
-/// Every given method ignores all arguments and forwards to `deserialize`.
-/// Note that `deserialize_enum` simply returns an `Error::invalid_type`.
-macro_rules! de_forward_to_deserialize {
-    ($($func:ident),*) => {
-        $(de_forward_to_deserialize!{func: $func})*
-    };
-    (func: deserialize_unit_struct) => {
-        de_forward_to_deserialize!{named: deserialize_unit_struct}
-    };
-    (func: deserialize_newtype_struct) => {
-        de_forward_to_deserialize!{named: deserialize_newtype_struct}
-    };
-    (func: deserialize_tuple) => {
-        de_forward_to_deserialize!{tup_fn: deserialize_tuple}
-    };
-    (func: deserialize_seq_fixed_size) => {
-        de_forward_to_deserialize!{tup_fn: deserialize_seq_fixed_size}
-    };
-    (func: deserialize_tuple_struct) => {
-        #[inline]
-        fn deserialize_tuple_struct<__V>(&mut self, _: &str, _: usize, visitor: __V) -> Result<__V::Value, Self::Error>
-            where __V: $crate::de::Visitor {
-            self.deserialize(visitor)
-        }
-    };
-    (func: deserialize_struct) => {
-        #[inline]
-        fn deserialize_struct<__V>(&mut self, _: &str, _: &[&str], visitor: __V) -> Result<__V::Value, Self::Error>
-            where __V: $crate::de::Visitor {
-            self.deserialize(visitor)
-        }
-    };
-    (func: deserialize_enum) => {
-        #[inline]
-        fn deserialize_enum<__V>(&mut self, _: &str, _: &[&str], _: __V) -> Result<__V::Value, Self::Error>
-            where __V: $crate::de::EnumVisitor {
-            Err($crate::de::Error::invalid_type($crate::de::Type::Enum))
-        }
-    };
-    (named: $func:ident) => {
-        #[inline]
-        fn $func<__V>(&mut self, _: &str, visitor: __V) -> Result<__V::Value, Self::Error>
-            where __V: $crate::de::Visitor {
-            self.deserialize(visitor)
-        }
-    };
-    (tup_fn: $func: ident) => {
-        #[inline]
-        fn $func<__V>(&mut self, _: usize, visitor: __V) -> Result<__V::Value, Self::Error>
-            where __V: $crate::de::Visitor {
-            self.deserialize(visitor)
-        }
-    };
-    (func: $func:ident) => {
-        #[inline]
-        fn $func<__V>(&mut self, visitor: __V) -> Result<__V::Value, Self::Error>
-            where __V: $crate::de::Visitor {
-            self.deserialize(visitor)
-        }
-    };
-}
-
-///////////////////////////////////////////////////////////////////////////////
-// modules come after macros
 
 pub mod impls;
 pub mod value;

serde/src/de/value.rs

@@ -178,20 +178,10 @@ impl<E> de::Deserializer for UnitDeserializer<E>
 {
     type Error = E;
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_enum,
-        deserialize_struct, deserialize_tuple_struct
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple enum ignored_any
     }
 
     fn deserialize<V>(&mut self, mut visitor: V) -> Result<V::Value, Self::Error>
@@ -229,21 +219,11 @@ macro_rules! primitive_deserializer {
         {
             type Error = E;
 
-            de_forward_to_deserialize!{
-                deserialize_bool,
-                deserialize_f64, deserialize_f32,
-                deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-                deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-                deserialize_char, deserialize_str, deserialize_string,
-                deserialize_ignored_any,
-                deserialize_bytes,
-                deserialize_unit_struct, deserialize_unit,
-                deserialize_seq, deserialize_seq_fixed_size,
-                deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-                deserialize_tuple,
-                deserialize_enum,
-                deserialize_struct, deserialize_tuple_struct,
-                deserialize_option
+            forward_to_deserialize! {
+                bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str
+                string unit option seq seq_fixed_size bytes map unit_struct
+                newtype_struct tuple_struct struct struct_field tuple enum
+                ignored_any
             }
 
             fn deserialize<V>(&mut self, mut visitor: V) -> Result<V::Value, Self::Error>
@@ -311,20 +291,10 @@ impl<'a, E> de::Deserializer for StrDeserializer<'a, E>
         visitor.visit(self)
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple ignored_any
     }
 }
 
@@ -408,20 +378,10 @@ impl<E> de::Deserializer for StringDeserializer<E>
         visitor.visit(self)
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple ignored_any
     }
 }
 
@@ -507,20 +467,10 @@ impl<'a, E> de::Deserializer for CowStrDeserializer<'a, E>
         visitor.visit(self)
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple ignored_any
     }
 }
 
@@ -599,21 +549,10 @@ impl<I, T, E> de::Deserializer for SeqDeserializer<I, E>
         visitor.visit_seq(self)
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_enum,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple enum ignored_any
     }
 }
 
@@ -722,21 +661,10 @@ impl<V_, E> de::Deserializer for SeqVisitorDeserializer<V_, E>
         visitor.visit_seq(&mut self.visitor)
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_enum,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple enum ignored_any
     }
 }
 
@@ -781,6 +709,15 @@ impl<I, K, V, E> MapDeserializer<I, K, V, E>
             marker: PhantomData,
         }
     }
+
+    fn next(&mut self) -> Option<(K, V)> {
+        self.iter.next().map(|(k, v)| {
+            if let Some(len) = self.len.as_mut() {
+                *len -= 1;
+            }
+            (k, v)
+        })
+    }
 }
 
 impl<I, K, V, E> de::Deserializer for MapDeserializer<I, K, V, E>
@@ -797,21 +734,26 @@ impl<I, K, V, E> de::Deserializer for MapDeserializer<I, K, V, E>
         visitor.visit_map(self)
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_enum,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    fn deserialize_seq<V_>(&mut self, mut visitor: V_) -> Result<V_::Value, Self::Error>
+        where V_: de::Visitor,
+    {
+        visitor.visit_seq(self)
+    }
+
+    fn deserialize_seq_fixed_size<V_>(&mut self, len: usize, mut visitor: V_) -> Result<V_::Value, Self::Error>
+        where V_: de::Visitor,
+    {
+        match self.len {
+            Some(map_len) if map_len == len => visitor.visit_seq(self),
+            Some(_) => Err(de::Error::invalid_length(len)),
+            None => visitor.visit_seq(self),
+        }
+    }
+
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option bytes map unit_struct newtype_struct tuple_struct struct
+        struct_field tuple enum ignored_any
     }
 }
 
@@ -826,14 +768,11 @@ impl<I, K, V, E> de::MapVisitor for MapDeserializer<I, K, V, E>
     fn visit_key<T>(&mut self) -> Result<Option<T>, Self::Error>
         where T: de::Deserialize,
     {
-        match self.iter.next() {
+        match self.next() {
             Some((key, value)) => {
-                if let Some(len) = self.len.as_mut() {
-                    *len -= 1;
-                }
                 self.value = Some(value);
                 let mut de = key.into_deserializer();
-                Ok(Some(try!(de::Deserialize::deserialize(&mut de))))
+                de::Deserialize::deserialize(&mut de).map(Some)
             }
             None => Ok(None),
         }
@@ -867,6 +806,123 @@ impl<I, K, V, E> de::MapVisitor for MapDeserializer<I, K, V, E>
     }
 }
 
+impl<I, K, V, E> de::SeqVisitor for MapDeserializer<I, K, V, E>
+    where I: Iterator<Item=(K, V)>,
+          K: ValueDeserializer<E>,
+          V: ValueDeserializer<E>,
+          E: de::Error,
+{
+    type Error = E;
+
+    fn visit<T>(&mut self) -> Result<Option<T>, Self::Error>
+        where T: de::Deserialize,
+    {
+        match self.next() {
+            Some(kv) => {
+                let mut de = PairDeserializer(Some(kv), PhantomData);
+                de::Deserialize::deserialize(&mut de).map(Some)
+            }
+            None => Ok(None),
+        }
+    }
+
+    fn end(&mut self) -> Result<(), Self::Error> {
+        de::MapVisitor::end(self)
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        de::MapVisitor::size_hint(self)
+    }
+}
+
+// Used in the `impl SeqVisitor for MapDeserializer` to visit the map as a
+// sequence of pairs.
+struct PairDeserializer<A, B, E>(Option<(A, B)>, PhantomData<E>);
+
+impl<A, B, E> de::Deserializer for PairDeserializer<A, B, E>
+    where A: ValueDeserializer<E>,
+          B: ValueDeserializer<E>,
+          E: de::Error
+{
+    type Error = E;
+
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option bytes map unit_struct newtype_struct tuple_struct struct
+        struct_field tuple enum ignored_any
+    }
+
+    fn deserialize<V>(&mut self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: de::Visitor,
+    {
+        self.deserialize_seq(visitor)
+    }
+
+    fn deserialize_seq<V>(&mut self, mut visitor: V) -> Result<V::Value, Self::Error>
+        where V: de::Visitor,
+    {
+        match self.0.take() {
+            Some((k, v)) => {
+                visitor.visit_seq(PairVisitor(Some(k), Some(v), PhantomData))
+            }
+            None => Err(de::Error::end_of_stream()),
+        }
+    }
+
+    fn deserialize_seq_fixed_size<V>(&mut self, len: usize, visitor: V) -> Result<V::Value, Self::Error>
+        where V: de::Visitor,
+    {
+        if len == 2 {
+            self.deserialize_seq(visitor)
+        } else {
+            Err(de::Error::invalid_length(len))
+        }
+    }
+}
+
+struct PairVisitor<A, B, E>(Option<A>, Option<B>, PhantomData<E>);
+
+impl<A, B, E> de::SeqVisitor for PairVisitor<A, B, E>
+    where A: ValueDeserializer<E>,
+          B: ValueDeserializer<E>,
+          E: de::Error,
+{
+    type Error = E;
+
+    fn visit<T>(&mut self) -> Result<Option<T>, Self::Error>
+        where T: de::Deserialize,
+    {
+        if let Some(k) = self.0.take() {
+            let mut de = k.into_deserializer();
+            de::Deserialize::deserialize(&mut de).map(Some)
+        } else if let Some(v) = self.1.take() {
+            let mut de = v.into_deserializer();
+            de::Deserialize::deserialize(&mut de).map(Some)
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn end(&mut self) -> Result<(), Self::Error> {
+        if self.1.is_none() {
+            Ok(())
+        } else {
+            Err(de::Error::invalid_length(self.size_hint().0))
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = if self.0.is_some() {
+            2
+        } else if self.1.is_some() {
+            1
+        } else {
+            0
+        };
+        (len, Some(len))
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 #[cfg(any(feature = "std", feature = "collections"))]
@@ -928,21 +984,10 @@ impl<V_, E> de::Deserializer for MapVisitorDeserializer<V_, E>
         visitor.visit_map(&mut self.visitor)
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_enum,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple enum ignored_any
     }
 }
 
@@ -975,25 +1020,13 @@ impl<'a, E> de::Deserializer for BytesDeserializer<'a, E>
         }
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_enum,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple enum ignored_any
     }
 }
 
-
 ///////////////////////////////////////////////////////////////////////////////
 
 #[cfg(any(feature = "std", feature = "collections"))]
@@ -1026,20 +1059,9 @@ impl<E> de::Deserializer for ByteBufDeserializer<E>
         }
     }
 
-    de_forward_to_deserialize!{
-        deserialize_bool,
-        deserialize_f64, deserialize_f32,
-        deserialize_u8, deserialize_u16, deserialize_u32, deserialize_u64, deserialize_usize,
-        deserialize_i8, deserialize_i16, deserialize_i32, deserialize_i64, deserialize_isize,
-        deserialize_char, deserialize_str, deserialize_string,
-        deserialize_ignored_any,
-        deserialize_bytes,
-        deserialize_unit_struct, deserialize_unit,
-        deserialize_seq, deserialize_seq_fixed_size,
-        deserialize_map, deserialize_newtype_struct, deserialize_struct_field,
-        deserialize_tuple,
-        deserialize_enum,
-        deserialize_struct, deserialize_tuple_struct,
-        deserialize_option
+    forward_to_deserialize! {
+        bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+        unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+        tuple_struct struct struct_field tuple enum ignored_any
     }
 }

serde/src/lib.rs

@@ -45,6 +45,9 @@ macro_rules! format {
     ($s:expr, $($rest:tt)*) => ($s)
 }
 
+#[macro_use]
+mod macros;
+
 pub mod bytes;
 pub mod de;
 #[cfg(feature = "std")]

serde/src/macros.rs

@@ -0,0 +1,179 @@
+#[cfg(feature = "std")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! forward_to_deserialize_method {
+    ($func:ident($($arg:ty),*)) => {
+        #[inline]
+        fn $func<__V>(&mut self, $(_: $arg,)* visitor: __V) -> ::std::result::Result<__V::Value, Self::Error>
+            where __V: $crate::de::Visitor
+        {
+            self.deserialize(visitor)
+        }
+    };
+}
+
+#[cfg(not(feature = "std"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! forward_to_deserialize_method {
+    ($func:ident($($arg:ty),*)) => {
+        #[inline]
+        fn $func<__V>(&mut self, $(_: $arg,)* visitor: __V) -> ::core::result::Result<__V::Value, Self::Error>
+            where __V: $crate::de::Visitor
+        {
+            self.deserialize(visitor)
+        }
+    };
+}
+
+#[cfg(feature = "std")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! forward_to_deserialize_enum {
+    () => {
+        #[inline]
+        fn deserialize_enum<__V>(&mut self, _: &str, _: &[&str], _: __V) -> ::std::result::Result<__V::Value, Self::Error>
+            where __V: $crate::de::EnumVisitor
+        {
+            Err($crate::de::Error::invalid_type($crate::de::Type::Enum))
+        }
+    };
+}
+
+#[cfg(not(feature = "std"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! forward_to_deserialize_enum {
+    () => {
+        #[inline]
+        fn deserialize_enum<__V>(&mut self, _: &str, _: &[&str], _: __V) -> ::core::result::Result<__V::Value, Self::Error>
+            where __V: $crate::de::EnumVisitor
+        {
+            Err($crate::de::Error::invalid_type($crate::de::Type::Enum))
+        }
+    };
+}
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! forward_to_deserialize_helper {
+    (bool) => {
+        forward_to_deserialize_method!{deserialize_bool()}
+    };
+    (usize) => {
+        forward_to_deserialize_method!{deserialize_usize()}
+    };
+    (u8) => {
+        forward_to_deserialize_method!{deserialize_u8()}
+    };
+    (u16) => {
+        forward_to_deserialize_method!{deserialize_u16()}
+    };
+    (u32) => {
+        forward_to_deserialize_method!{deserialize_u32()}
+    };
+    (u64) => {
+        forward_to_deserialize_method!{deserialize_u64()}
+    };
+    (isize) => {
+        forward_to_deserialize_method!{deserialize_isize()}
+    };
+    (i8) => {
+        forward_to_deserialize_method!{deserialize_i8()}
+    };
+    (i16) => {
+        forward_to_deserialize_method!{deserialize_i16()}
+    };
+    (i32) => {
+        forward_to_deserialize_method!{deserialize_i32()}
+    };
+    (i64) => {
+        forward_to_deserialize_method!{deserialize_i64()}
+    };
+    (f32) => {
+        forward_to_deserialize_method!{deserialize_f32()}
+    };
+    (f64) => {
+        forward_to_deserialize_method!{deserialize_f64()}
+    };
+    (char) => {
+        forward_to_deserialize_method!{deserialize_char()}
+    };
+    (str) => {
+        forward_to_deserialize_method!{deserialize_str()}
+    };
+    (string) => {
+        forward_to_deserialize_method!{deserialize_string()}
+    };
+    (unit) => {
+        forward_to_deserialize_method!{deserialize_unit()}
+    };
+    (option) => {
+        forward_to_deserialize_method!{deserialize_option()}
+    };
+    (seq) => {
+        forward_to_deserialize_method!{deserialize_seq()}
+    };
+    (seq_fixed_size) => {
+        forward_to_deserialize_method!{deserialize_seq_fixed_size(usize)}
+    };
+    (bytes) => {
+        forward_to_deserialize_method!{deserialize_bytes()}
+    };
+    (map) => {
+        forward_to_deserialize_method!{deserialize_map()}
+    };
+    (unit_struct) => {
+        forward_to_deserialize_method!{deserialize_unit_struct(&'static str)}
+    };
+    (newtype_struct) => {
+        forward_to_deserialize_method!{deserialize_newtype_struct(&'static str)}
+    };
+    (tuple_struct) => {
+        forward_to_deserialize_method!{deserialize_tuple_struct(&'static str, usize)}
+    };
+    (struct) => {
+        forward_to_deserialize_method!{deserialize_struct(&'static str, &'static [&'static str])}
+    };
+    (struct_field) => {
+        forward_to_deserialize_method!{deserialize_struct_field()}
+    };
+    (tuple) => {
+        forward_to_deserialize_method!{deserialize_tuple(usize)}
+    };
+    (ignored_any) => {
+        forward_to_deserialize_method!{deserialize_ignored_any()}
+    };
+    (enum) => {
+        forward_to_deserialize_enum!();
+    };
+}
+
+/// Helper to forward `Deserializer` methods to `Deserializer::deserialize`.
+/// Every given method ignores all arguments and forwards to `deserialize`.
+/// Note that `deserialize_enum` simply returns an `Error::invalid_type`; a
+/// better approach is tracked in [serde-rs/serde#521][1].
+///
+/// ```rust,ignore
+/// impl Deserializer for MyDeserializer {
+///     fn deserialize<V>(&mut self, visitor: V) -> Result<V::Value, Self::Error>
+///         where V: Visitor
+///     {
+///         /* ... */
+///     }
+///
+///     forward_to_deserialize! {
+///         bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 char str string
+///         unit option seq seq_fixed_size bytes map unit_struct newtype_struct
+///         tuple_struct struct struct_field tuple enum ignored_any
+///     }
+/// }
+/// ```
+///
+/// [1]: https://github.com/serde-rs/serde/issues/521
+#[macro_export]
+macro_rules! forward_to_deserialize {
+    ($($func:ident)*) => {
+        $(forward_to_deserialize_helper!{$func})*
+    };
+}

serde_codegen/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_codegen"
-version = "0.8.6"
+version = "0.8.7"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros to auto-generate implementations for the serde framework"

serde_codegen/src/ser.rs

@@ -4,6 +4,7 @@ use syntax::ast::{self, Ident, MetaItem};
 use syntax::codemap::Span;
 use syntax::ext::base::{Annotatable, ExtCtxt};
 use syntax::ptr::P;
+use syntax::tokenstream::TokenTree;
 
 use bound;
 use span;
@@ -226,9 +227,10 @@ fn serialize_tuple_struct(
 
     let type_name = name_expr(builder, item_attrs.name());
     let len = serialize_stmts.len();
+    let let_mut = mut_if(cx, len > 0);
 
     quote_block!(cx, {
-        let mut state = try!(_serializer.serialize_tuple_struct($type_name, $len));
+        let $let_mut state = try!(_serializer.serialize_tuple_struct($type_name, $len));
         $serialize_stmts
         _serializer.serialize_tuple_struct_end(state)
     }).unwrap()
@@ -253,8 +255,14 @@ fn serialize_struct(
     );
 
     let type_name = name_expr(builder, item_attrs.name());
-    let len = fields.iter()
+
+    let mut serialized_fields = fields.iter()
         .filter(|&field| !field.attrs.skip_serializing())
+        .peekable();
+
+    let let_mut = mut_if(cx, serialized_fields.peek().is_some());
+
+    let len = serialized_fields
         .map(|field| {
             let ident = field.ident.expect("struct has unnamed fields");
             let field_expr = quote_expr!(cx, &self.$ident);
@@ -267,7 +275,7 @@ fn serialize_struct(
         .fold(quote_expr!(cx, 0), |sum, expr| quote_expr!(cx, $sum + $expr));
 
     quote_block!(cx, {
-        let mut state = try!(_serializer.serialize_struct($type_name, $len));
+        let $let_mut state = try!(_serializer.serialize_struct($type_name, $len));
         $serialize_fields
         _serializer.serialize_struct_end(state)
     }).unwrap()
@@ -458,9 +466,10 @@ fn serialize_tuple_variant(
     );
 
     let len = serialize_stmts.len();
+    let let_mut = mut_if(cx, len > 0);
 
     quote_block!(cx, {
-        let mut state = try!(_serializer.serialize_tuple_variant($type_name, $variant_index, $variant_name, $len));
+        let $let_mut state = try!(_serializer.serialize_tuple_variant($type_name, $variant_index, $variant_name, $len));
         $serialize_stmts
         _serializer.serialize_tuple_variant_end(state)
     }).unwrap()
@@ -488,8 +497,14 @@ fn serialize_struct_variant(
     );
 
     let item_name = name_expr(builder, item_attrs.name());
-    let len = fields.iter()
+
+    let mut serialized_fields = fields.iter()
         .filter(|&field| !field.attrs.skip_serializing())
+        .peekable();
+
+    let let_mut = mut_if(cx, serialized_fields.peek().is_some());
+
+    let len = serialized_fields
         .map(|field| {
             let ident = field.ident.expect("struct has unnamed fields");
             let field_expr = quote_expr!(cx, $ident);
@@ -502,7 +517,7 @@ fn serialize_struct_variant(
         .fold(quote_expr!(cx, 0), |sum, expr| quote_expr!(cx, $sum + $expr));
 
     quote_block!(cx, {
-        let mut state = try!(_serializer.serialize_struct_variant(
+        let $let_mut state = try!(_serializer.serialize_struct_variant(
             $item_name,
             $variant_index,
             $variant_name,
@@ -532,19 +547,21 @@ fn serialize_tuple_struct_visitor(
             };
 
             let skip = field.attrs.skip_serializing_if()
-                .map(|path| quote_expr!(cx, $path($field_expr)))
-                .unwrap_or(quote_expr!(cx, false));
+                .map(|path| quote_expr!(cx, $path($field_expr)));
 
             if let Some(path) = field.attrs.serialize_with() {
                 field_expr = wrap_serialize_with(cx, builder,
                     &structure_ty, generics, &field.ty, path, field_expr);
             }
 
-            quote_stmt!(cx,
-                if !$skip {
-                    try!(_serializer.$func(&mut state, $field_expr));
-                }
-            ).unwrap()
+            let ser = quote_expr!(cx,
+                try!(_serializer.$func(&mut state, $field_expr));
+            );
+
+            match skip {
+                None => quote_stmt!(cx, $ser).unwrap(),
+                Some(skip) => quote_stmt!(cx, if !$skip { $ser }).unwrap(),
+            }
         })
         .collect()
 }
@@ -571,19 +588,21 @@ fn serialize_struct_visitor(
             let key_expr = name_expr(builder, field.attrs.name());
 
             let skip = field.attrs.skip_serializing_if()
-                .map(|path| quote_expr!(cx, $path($field_expr)))
-                .unwrap_or(quote_expr!(cx, false));
+                .map(|path| quote_expr!(cx, $path($field_expr)));
 
             if let Some(path) = field.attrs.serialize_with() {
                 field_expr = wrap_serialize_with(cx, builder,
                     &structure_ty, generics, &field.ty, path, field_expr)
             }
 
-            quote_stmt!(cx,
-                if !$skip {
-                    try!(_serializer.$func(&mut state, $key_expr, $field_expr));
-                }
-            ).unwrap()
+            let ser = quote_expr!(cx,
+                try!(_serializer.$func(&mut state, $key_expr, $field_expr));
+            );
+
+            match skip {
+                None => quote_stmt!(cx, $ser).unwrap(),
+                Some(skip) => quote_stmt!(cx, if !$skip { $ser }).unwrap(),
+            }
         })
         .collect()
 }
@@ -637,3 +656,17 @@ fn name_expr(
 ) -> P<ast::Expr> {
     builder.expr().str(name.serialize_name())
 }
+
+// Serialization of an empty struct results in code like:
+//
+//     let mut state = try!(serializer.serialize_struct("S", 0));
+//     serializer.serialize_struct_end(state)
+//
+// where we want to omit the `mut` to avoid a warning.
+fn mut_if(cx: &ExtCtxt, is_mut: bool) -> Vec<TokenTree> {
+    if is_mut {
+        quote_tokens!(cx, mut)
+    } else {
+        Vec::new()
+    }
+}

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "0.8.6"
+version = "0.8.7"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -15,9 +15,9 @@ name = "serde_derive"
 rustc-macro = true
 
 [dependencies]
-serde_codegen = { version = "=0.8.6", path = "../serde_codegen" }
+serde_codegen = { version = "=0.8.7", path = "../serde_codegen" }
 
 [dev-dependencies]
 fnv = "1.0"
-serde = { version = "0.8.6", path = "../serde" }
-serde_test = { version = "0.8.6", path = "../serde_test" }
+serde = { version = "0.8.7", path = "../serde" }
+serde_test = { version = "0.8.7", path = "../serde_test" }

serde_macros/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_macros"
-version = "0.8.6"
+version = "0.8.7"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros to auto-generate implementations for the serde framework"
@@ -23,14 +23,14 @@ unstable-testing = [
 
 [dependencies]
 clippy = { version = "^0.*", optional = true }
-serde_codegen = { version = "=0.8.6", default-features = false, features = ["unstable"], path = "../serde_codegen" }
+serde_codegen = { version = "=0.8.7", default-features = false, features = ["unstable"], path = "../serde_codegen" }
 
 [dev-dependencies]
 compiletest_rs = "^0.2.0"
 fnv = "1.0"
 rustc-serialize = "^0.3.16"
-serde = { version = "0.8.6", path = "../serde" }
-serde_test = { version = "0.8.6", path = "../serde_test" }
+serde = { version = "0.8.7", path = "../serde" }
+serde_test = { version = "0.8.7", path = "../serde_test" }
 
 [[test]]
 name = "test"

serde_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_test"
-version = "0.8.6"
+version = "0.8.7"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Token De/Serializer for testing De/Serialize implementations"
@@ -12,4 +12,4 @@ keywords = ["serde", "serialization"]
 include = ["Cargo.toml", "src/**/*.rs"]
 
 [dependencies]
-serde = { version = "0.8.6", path = "../serde" }
+serde = { version = "0.8.7", path = "../serde" }

testing/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_testing"
-version = "0.8.6"
+version = "0.8.7"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "A generic serialization/deserialization framework"

testing/tests/test_gen.rs

@@ -187,6 +187,16 @@ fn test_gen() {
     #[serde(bound(deserialize = "T::Owned: Deserialize"))]
     struct CowT<'a, T: ?Sized + 'a + ToOwned>(Cow<'a, T>);
     assert::<CowT<str>>();
+
+    #[derive(Serialize, Deserialize)]
+    struct EmptyStruct {}
+    assert::<EmptyStruct>();
+
+    #[derive(Serialize, Deserialize)]
+    enum EmptyEnumVariant {
+        EmptyStruct {},
+    }
+    assert::<EmptyEnumVariant>();
 }
 
 //////////////////////////////////////////////////////////////////////////