Release 0.9.0-rc2

Filter the slice of expected field and variant names

.travis.yml

@@ -1,7 +1,6 @@
 sudo: false
 language: rust
 rust:
-- 1.12.0
 - 1.13.0
 - stable
 - beta

LICENSE

@@ -1,33 +0,0 @@
-See LICENSE-APACHE and LICENSE-MIT.
-
-----
-
-bench_log is derived from https://github.com/cloudflare/goser, which has the
-following license:
-
-Copyright (c) 2013, CloudFlare, Inc.
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
-
-* Redistributions of source code must retain the above copyright
-  notice, this list of conditions and the following disclaimer.
-* Redistributions in binary form must reproduce the above copyright
-  notice, this list of conditions and the following disclaimer in the
-  documentation and/or other materials provided with the distribution.
-* Neither the name of the author nor the
-  names of its contributors may be used to endorse or promote products
-  derived from this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
-ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
-DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
-(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
-ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "0.9.0-rc1"
+version = "0.9.0-rc2"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -9,6 +9,7 @@ repository = "https://github.com/serde-rs/serde"
 documentation = "https://docs.serde.rs/serde/"
 readme = "../README.md"
 keywords = ["serde", "serialization"]
+categories = ["encoding"]
 include = ["Cargo.toml", "src/**/*.rs"]
 
 [features]

serde/src/bytes.rs

@@ -181,6 +181,10 @@ mod bytebuf {
     impl de::Visitor for ByteBufVisitor {
         type Value = ByteBuf;
 
+        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            formatter.write_str("byte array")
+        }
+
         #[inline]
         fn visit_unit<E>(self) -> Result<ByteBuf, E>
             where E: de::Error,
@@ -234,7 +238,7 @@ mod bytebuf {
         fn deserialize<D>(deserializer: D) -> Result<ByteBuf, D::Error>
             where D: de::Deserializer
         {
-            deserializer.deserialize_bytes(ByteBufVisitor)
+            deserializer.deserialize_byte_buf(ByteBufVisitor)
         }
     }
 }

serde/src/de/impls.rs

@@ -32,6 +32,7 @@ use collections::enum_set::{CLike, EnumSet};
 #[cfg(all(feature = "unstable", feature = "collections"))]
 use collections::borrow::ToOwned;
 
+use core::fmt;
 use core::hash::{Hash, BuildHasher};
 use core::marker::PhantomData;
 #[cfg(feature = "std")]
@@ -69,7 +70,7 @@ use de::{
     Error,
     MapVisitor,
     SeqVisitor,
-    Type,
+    Unexpected,
     VariantVisitor,
     Visitor,
 };
@@ -83,6 +84,10 @@ pub struct UnitVisitor;
 impl Visitor for UnitVisitor {
     type Value = ();
 
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("unit")
+    }
+
     fn visit_unit<E>(self) -> Result<(), E>
         where E: Error,
     {
@@ -112,6 +117,10 @@ pub struct BoolVisitor;
 impl Visitor for BoolVisitor {
     type Value = bool;
 
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a boolean")
+    }
+
     fn visit_bool<E>(self, v: bool) -> Result<bool, E>
         where E: Error,
     {
@@ -124,7 +133,7 @@ impl Visitor for BoolVisitor {
         match s.trim_matches(::utils::Pattern_White_Space) {
             "true" => Ok(true),
             "false" => Ok(false),
-            _ => Err(Error::invalid_type(Type::Bool)),
+            _ => Err(Error::invalid_type(Unexpected::Str(s), &self)),
         }
     }
 }
@@ -140,70 +149,59 @@ impl Deserialize for bool {
 ///////////////////////////////////////////////////////////////////////////////
 
 macro_rules! impl_deserialize_num_method {
-    ($src_ty:ty, $method:ident, $from_method:ident, $ty:expr) => {
+    ($ty:ident, $src_ty:ident, $method:ident, $from_method:ident, $group:ident, $group_ty:ident) => {
         #[inline]
-        fn $method<E>(self, v: $src_ty) -> Result<T, E>
+        fn $method<E>(self, v: $src_ty) -> Result<$ty, E>
             where E: Error,
         {
             match FromPrimitive::$from_method(v) {
                 Some(v) => Ok(v),
-                None => Err(Error::invalid_type($ty)),
+                None => Err(Error::invalid_value(Unexpected::$group(v as $group_ty), &self)),
             }
         }
     }
 }
 
-/// A visitor that produces a primitive type.
-struct PrimitiveVisitor<T> {
-    marker: PhantomData<T>,
-}
-
-impl<T> PrimitiveVisitor<T> {
-    /// Construct a new `PrimitiveVisitor`.
-    #[inline]
-    fn new() -> Self {
-        PrimitiveVisitor {
-            marker: PhantomData,
-        }
-    }
-}
-
-impl<T> Visitor for PrimitiveVisitor<T>
-    where T: Deserialize + FromPrimitive + str::FromStr
-{
-    type Value = T;
-
-    impl_deserialize_num_method!(isize, visit_isize, from_isize, Type::Isize);
-    impl_deserialize_num_method!(i8, visit_i8, from_i8, Type::I8);
-    impl_deserialize_num_method!(i16, visit_i16, from_i16, Type::I16);
-    impl_deserialize_num_method!(i32, visit_i32, from_i32, Type::I32);
-    impl_deserialize_num_method!(i64, visit_i64, from_i64, Type::I64);
-    impl_deserialize_num_method!(usize, visit_usize, from_usize, Type::Usize);
-    impl_deserialize_num_method!(u8, visit_u8, from_u8, Type::U8);
-    impl_deserialize_num_method!(u16, visit_u16, from_u16, Type::U16);
-    impl_deserialize_num_method!(u32, visit_u32, from_u32, Type::U32);
-    impl_deserialize_num_method!(u64, visit_u64, from_u64, Type::U64);
-    impl_deserialize_num_method!(f32, visit_f32, from_f32, Type::F32);
-    impl_deserialize_num_method!(f64, visit_f64, from_f64, Type::F64);
-
-    #[inline]
-    fn visit_str<E>(self, s: &str) -> Result<T, E>
-        where E: Error,
-    {
-        str::FromStr::from_str(s.trim_matches(::utils::Pattern_White_Space)).or_else(|_| {
-            Err(Error::invalid_type(Type::Str))
-        })
-    }
-}
-
 macro_rules! impl_deserialize_num {
-    ($ty:ty, $method:ident) => {
+    ($ty:ident, $method:ident) => {
         impl Deserialize for $ty {
             #[inline]
             fn deserialize<D>(deserializer: D) -> Result<$ty, D::Error>
                 where D: Deserializer,
             {
-                deserializer.$method(PrimitiveVisitor::new())
+                struct PrimitiveVisitor;
+
+                impl Visitor for PrimitiveVisitor {
+                    type Value = $ty;
+
+                    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                        formatter.write_str(stringify!($ty))
+                    }
+
+                    impl_deserialize_num_method!($ty, isize, visit_isize, from_isize, Signed, i64);
+                    impl_deserialize_num_method!($ty, i8, visit_i8, from_i8, Signed, i64);
+                    impl_deserialize_num_method!($ty, i16, visit_i16, from_i16, Signed, i64);
+                    impl_deserialize_num_method!($ty, i32, visit_i32, from_i32, Signed, i64);
+                    impl_deserialize_num_method!($ty, i64, visit_i64, from_i64, Signed, i64);
+                    impl_deserialize_num_method!($ty, usize, visit_usize, from_usize, Unsigned, u64);
+                    impl_deserialize_num_method!($ty, u8, visit_u8, from_u8, Unsigned, u64);
+                    impl_deserialize_num_method!($ty, u16, visit_u16, from_u16, Unsigned, u64);
+                    impl_deserialize_num_method!($ty, u32, visit_u32, from_u32, Unsigned, u64);
+                    impl_deserialize_num_method!($ty, u64, visit_u64, from_u64, Unsigned, u64);
+                    impl_deserialize_num_method!($ty, f32, visit_f32, from_f32, Float, f64);
+                    impl_deserialize_num_method!($ty, f64, visit_f64, from_f64, Float, f64);
+
+                    #[inline]
+                    fn visit_str<E>(self, s: &str) -> Result<$ty, E>
+                        where E: Error,
+                    {
+                        str::FromStr::from_str(s.trim_matches(::utils::Pattern_White_Space)).or_else(|_| {
+                            Err(Error::invalid_type(Unexpected::Str(s), &self))
+                        })
+                    }
+                }
+
+                deserializer.$method(PrimitiveVisitor)
             }
         }
     }
@@ -229,6 +227,10 @@ struct CharVisitor;
 impl Visitor for CharVisitor {
     type Value = char;
 
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a character")
+    }
+
     #[inline]
     fn visit_char<E>(self, v: char) -> Result<char, E>
         where E: Error,
@@ -241,14 +243,9 @@ impl Visitor for CharVisitor {
         where E: Error,
     {
         let mut iter = v.chars();
-        if let Some(v) = iter.next() {
-            if iter.next().is_some() {
-                Err(Error::invalid_type(Type::Char))
-            } else {
-                Ok(v)
-            }
-        } else {
-            Err(Error::end_of_stream())
+        match (iter.next(), iter.next()) {
+            (Some(c), None) => Ok(c),
+            _ => Err(Error::invalid_value(Unexpected::Str(v), &self)),
         }
     }
 }
@@ -271,6 +268,10 @@ struct StringVisitor;
 impl Visitor for StringVisitor {
     type Value = String;
 
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a string")
+    }
+
     fn visit_str<E>(self, v: &str) -> Result<String, E>
         where E: Error,
     {
@@ -294,7 +295,7 @@ impl Visitor for StringVisitor {
     {
         match str::from_utf8(v) {
             Ok(s) => Ok(s.to_owned()),
-            Err(_) => Err(Error::invalid_type(Type::String)),
+            Err(_) => Err(Error::invalid_value(Unexpected::Bytes, &self)),
         }
     }
 
@@ -303,7 +304,7 @@ impl Visitor for StringVisitor {
     {
         match String::from_utf8(v) {
             Ok(s) => Ok(s),
-            Err(_) => Err(Error::invalid_type(Type::String)),
+            Err(_) => Err(Error::invalid_value(Unexpected::Bytes, &self)),
         }
     }
 }
@@ -328,6 +329,10 @@ impl<
 > Visitor for OptionVisitor<T> {
     type Value = Option<T>;
 
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("option")
+    }
+
     #[inline]
     fn visit_unit<E>(self) -> Result<Option<T>, E>
         where E: Error,
@@ -368,6 +373,10 @@ pub struct PhantomDataVisitor<T> {
 impl<T> Visitor for PhantomDataVisitor<T> {
     type Value = PhantomData<T>;
 
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("unit")
+    }
+
     #[inline]
     fn visit_unit<E>(self) -> Result<PhantomData<T>, E>
         where E: Error,
@@ -417,6 +426,10 @@ macro_rules! seq_impl {
         {
             type Value = $ty;
 
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("a sequence")
+            }
+
             #[inline]
             fn visit_unit<E>(self) -> Result<$ty, E>
                 where E: Error,
@@ -531,6 +544,10 @@ impl<A> ArrayVisitor<A> {
 impl<T> Visitor for ArrayVisitor<[T; 0]> where T: Deserialize {
     type Value = [T; 0];
 
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("an empty array")
+    }
+
     #[inline]
     fn visit_unit<E>(self) -> Result<[T; 0], E>
         where E: Error,
@@ -562,6 +579,10 @@ macro_rules! array_impls {
             impl<T> Visitor for ArrayVisitor<[T; $len]> where T: Deserialize {
                 type Value = [T; $len];
 
+                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                    formatter.write_str(concat!("an array of length ", $len))
+                }
+
                 #[inline]
                 fn visit_seq<V>(self, mut visitor: V) -> Result<[T; $len], V::Error>
                     where V: SeqVisitor,
@@ -569,7 +590,7 @@ macro_rules! array_impls {
                     $(
                         let $name = match try!(visitor.visit()) {
                             Some(val) => val,
-                            None => return Err(Error::end_of_stream()),
+                            None => return Err(Error::invalid_length(0, &self)),
                         };
                     )+
 
@@ -645,6 +666,10 @@ macro_rules! tuple_impls {
             impl<$($name: Deserialize),+> Visitor for $visitor<$($name,)+> {
                 type Value = ($($name,)+);
 
+                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                    formatter.write_str(concat!("a tuple of size ", $len))
+                }
+
                 #[inline]
                 #[allow(non_snake_case)]
                 fn visit_seq<V>(self, mut visitor: V) -> Result<($($name,)+), V::Error>
@@ -653,7 +678,7 @@ macro_rules! tuple_impls {
                     $(
                         let $name = match try!(visitor.visit()) {
                             Some(value) => value,
-                            None => return Err(Error::end_of_stream()),
+                            None => return Err(Error::invalid_length(0, &self)),
                         };
                     )+
 
@@ -723,6 +748,10 @@ macro_rules! map_impl {
         {
             type Value = $ty;
 
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("a map")
+            }
+
             #[inline]
             fn visit_unit<E>(self) -> Result<$ty, E>
                 where E: Error,
@@ -785,7 +814,7 @@ impl Deserialize for net::IpAddr {
         let s = try!(String::deserialize(deserializer));
         match s.parse() {
             Ok(s) => Ok(s),
-            Err(err) => Err(D::Error::invalid_value(&err.to_string())),
+            Err(err) => Err(D::Error::custom(err)),
         }
     }
 }
@@ -798,7 +827,7 @@ impl Deserialize for net::Ipv4Addr {
         let s = try!(String::deserialize(deserializer));
         match s.parse() {
             Ok(s) => Ok(s),
-            Err(err) => Err(D::Error::invalid_value(&err.to_string())),
+            Err(err) => Err(D::Error::custom(err)),
         }
     }
 }
@@ -811,7 +840,7 @@ impl Deserialize for net::Ipv6Addr {
         let s = try!(String::deserialize(deserializer));
         match s.parse() {
             Ok(s) => Ok(s),
-            Err(err) => Err(D::Error::invalid_value(&err.to_string())),
+            Err(err) => Err(D::Error::custom(err)),
         }
     }
 }
@@ -826,7 +855,7 @@ impl Deserialize for net::SocketAddr {
         let s = try!(String::deserialize(deserializer));
         match s.parse() {
             Ok(s) => Ok(s),
-            Err(err) => Err(D::Error::invalid_value(&err.to_string())),
+            Err(err) => Err(D::Error::custom(err)),
         }
     }
 }
@@ -839,7 +868,7 @@ impl Deserialize for net::SocketAddrV4 {
         let s = try!(String::deserialize(deserializer));
         match s.parse() {
             Ok(s) => Ok(s),
-            Err(err) => Err(D::Error::invalid_value(&err.to_string())),
+            Err(err) => Err(D::Error::custom(err)),
         }
     }
 }
@@ -852,7 +881,7 @@ impl Deserialize for net::SocketAddrV6 {
         let s = try!(String::deserialize(deserializer));
         match s.parse() {
             Ok(s) => Ok(s),
-            Err(err) => Err(D::Error::invalid_value(&err.to_string())),
+            Err(err) => Err(D::Error::custom(err)),
         }
     }
 }
@@ -866,6 +895,10 @@ struct PathBufVisitor;
 impl Visitor for PathBufVisitor {
     type Value = path::PathBuf;
 
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("path string")
+    }
+
     fn visit_str<E>(self, v: &str) -> Result<path::PathBuf, E>
         where E: Error,
     {
@@ -875,7 +908,7 @@ impl Visitor for PathBufVisitor {
     fn visit_string<E>(self, v: String) -> Result<path::PathBuf, E>
         where E: Error,
     {
-        self.visit_str(&v)
+        Ok(From::from(v))
     }
 }
 
@@ -977,13 +1010,17 @@ impl Deserialize for Duration {
                 impl Visitor for FieldVisitor {
                     type Value = Field;
 
+                    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                        formatter.write_str("`secs` or `nanos`")
+                    }
+
                     fn visit_usize<E>(self, value: usize) -> Result<Field, E>
                         where E: Error,
                     {
                         match value {
                             0usize => Ok(Field::Secs),
                             1usize => Ok(Field::Nanos),
-                            _ => Err(Error::invalid_value("expected a field")),
+                            _ => Err(Error::invalid_value(Unexpected::Unsigned(value as u64), &self)),
                         }
                     }
 
@@ -993,7 +1030,7 @@ impl Deserialize for Duration {
                         match value {
                             "secs" => Ok(Field::Secs),
                             "nanos" => Ok(Field::Nanos),
-                            _ => Err(Error::unknown_field(value)),
+                            _ => Err(Error::unknown_field(value, FIELDS)),
                         }
                     }
 
@@ -1005,7 +1042,7 @@ impl Deserialize for Duration {
                             b"nanos" => Ok(Field::Nanos),
                             _ => {
                                 let value = String::from_utf8_lossy(value);
-                                Err(Error::unknown_field(&value))
+                                Err(Error::unknown_field(&value, FIELDS))
                             }
                         }
                     }
@@ -1020,19 +1057,23 @@ impl Deserialize for Duration {
         impl Visitor for DurationVisitor {
             type Value = Duration;
 
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("struct Duration")
+            }
+
             fn visit_seq<V>(self, mut visitor: V) -> Result<Duration, V::Error>
                 where V: SeqVisitor,
             {
                 let secs: u64 = match try!(visitor.visit()) {
                     Some(value) => value,
                     None => {
-                        return Err(Error::invalid_length(0));
+                        return Err(Error::invalid_length(0, &self));
                     }
                 };
                 let nanos: u32 = match try!(visitor.visit()) {
                     Some(value) => value,
                     None => {
-                        return Err(Error::invalid_length(1));
+                        return Err(Error::invalid_length(1, &self));
                     }
                 };
                 Ok(Duration::new(secs, nanos))
@@ -1061,11 +1102,11 @@ impl Deserialize for Duration {
                 }
                 let secs = match secs {
                     Some(secs) => secs,
-                    None => try!(visitor.missing_field("secs")),
+                    None => return Err(<V::Error as Error>::missing_field("secs")),
                 };
                 let nanos = match nanos {
                     Some(nanos) => nanos,
-                    None => try!(visitor.missing_field("nanos")),
+                    None => return Err(<V::Error as Error>::missing_field("nanos")),
                 };
                 Ok(Duration::new(secs, nanos))
             }
@@ -1083,7 +1124,7 @@ impl<T> Deserialize for NonZero<T> where T: Deserialize + PartialEq + Zeroable +
     fn deserialize<D>(deserializer: D) -> Result<NonZero<T>, D::Error> where D: Deserializer {
         let value = try!(Deserialize::deserialize(deserializer));
         if value == Zero::zero() {
-            return Err(Error::invalid_value("expected a non-zero value"))
+            return Err(Error::custom("expected a non-zero value"))
         }
         unsafe {
             Ok(NonZero::new(value))
@@ -1112,23 +1153,15 @@ impl<T, E> Deserialize for Result<T, E> where T: Deserialize, E: Deserialize {
                 impl Visitor for FieldVisitor {
                     type Value = Field;
 
-                    #[cfg(any(feature = "std", feature = "collections"))]
-                    fn visit_usize<E>(self, value: usize) -> Result<Field, E> where E: Error {
-                        #[cfg(feature = "collections")]
-                        use collections::string::ToString;
-                        match value {
-                            0 => Ok(Field::Ok),
-                            1 => Ok(Field::Err),
-                            _ => Err(Error::unknown_field(&value.to_string())),
-                        }
+                    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                        formatter.write_str("`Ok` or `Err`")
                     }
 
-                    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
                     fn visit_usize<E>(self, value: usize) -> Result<Field, E> where E: Error {
                         match value {
                             0 => Ok(Field::Ok),
                             1 => Ok(Field::Err),
-                            _ => Err(Error::unknown_field("some number")),
+                            _ => Err(Error::invalid_value(Unexpected::Unsigned(value as u64), &self)),
                         }
                     }
 
@@ -1136,7 +1169,7 @@ impl<T, E> Deserialize for Result<T, E> where T: Deserialize, E: Deserialize {
                         match value {
                             "Ok" => Ok(Field::Ok),
                             "Err" => Ok(Field::Err),
-                            _ => Err(Error::unknown_field(value)),
+                            _ => Err(Error::unknown_variant(value, VARIANTS)),
                         }
                     }
 
@@ -1146,8 +1179,8 @@ impl<T, E> Deserialize for Result<T, E> where T: Deserialize, E: Deserialize {
                             b"Err" => Ok(Field::Err),
                             _ => {
                                 match str::from_utf8(value) {
-                                    Ok(value) => Err(Error::unknown_field(value)),
-                                    Err(_) => Err(Error::invalid_type(Type::String)),
+                                    Ok(value) => Err(Error::unknown_variant(value, VARIANTS)),
+                                    Err(_) => Err(Error::invalid_value(Unexpected::Bytes, &self)),
                                 }
                             }
                         }
@@ -1166,6 +1199,10 @@ impl<T, E> Deserialize for Result<T, E> where T: Deserialize, E: Deserialize {
         {
             type Value = Result<T, E>;
 
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("enum Result")
+            }
+
             fn visit_enum<V>(self, visitor: V) -> Result<Result<T, E>, V::Error>
                 where V: EnumVisitor
             {
@@ -1198,6 +1235,10 @@ impl Deserialize for IgnoredAny {
         impl Visitor for IgnoredAnyVisitor {
             type Value = IgnoredAny;
 
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("anything at all")
+            }
+
             #[inline]
             fn visit_bool<E>(self, _: bool) -> Result<IgnoredAny, E> {
                 Ok(IgnoredAny)

serde/src/de/private.rs

@@ -0,0 +1,40 @@
+use core::marker::PhantomData;
+
+use de::{Deserialize, Deserializer, Error, Visitor};
+
+/// If the missing field is of type `Option<T>` then treat is as `None`,
+/// otherwise it is an error.
+pub fn missing_field<V, E>(field: &'static str) -> Result<V, E>
+    where V: Deserialize,
+          E: Error
+{
+    struct MissingFieldDeserializer<E>(&'static str, PhantomData<E>);
+
+    impl<E> Deserializer for MissingFieldDeserializer<E>
+        where E: Error
+    {
+        type Error = E;
+
+        fn deserialize<V>(self, _visitor: V) -> Result<V::Value, E>
+            where V: Visitor
+        {
+            Err(Error::missing_field(self.0))
+        }
+
+        fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, E>
+            where V: Visitor
+        {
+            visitor.visit_none()
+        }
+
+        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 byte_buf map unit_struct
+            newtype_struct tuple_struct struct struct_field tuple enum
+            ignored_any
+        }
+    }
+
+    let deserializer = MissingFieldDeserializer(field, PhantomData);
+    Deserialize::deserialize(deserializer)
+}

serde/src/de/value.rs

@@ -28,6 +28,10 @@ use collections::{
 };
 #[cfg(all(feature = "collections", not(feature = "std")))]
 use collections::borrow::Cow;
+#[cfg(all(feature = "collections", not(feature = "std")))]
+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;
@@ -38,112 +42,57 @@ use std::error;
 #[cfg(not(feature = "std"))]
 use error;
 
-use core::fmt;
+use core::fmt::{self, Display};
+use core::iter::{self,  Iterator};
 use core::marker::PhantomData;
 
-use de::{self, SeqVisitor};
+use de::{self, Expected, SeqVisitor};
 use bytes;
 
 ///////////////////////////////////////////////////////////////////////////////
 
 /// This represents all the possible errors that can occur using the `ValueDeserializer`.
 #[derive(Clone, Debug, PartialEq)]
-pub enum Error {
-    /// The value had some custom error.
-    #[cfg(any(feature = "std", feature = "collections"))]
-    Custom(String),
-    /// The value had some custom error.
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    Custom(&'static str),
+pub struct Error(ErrorImpl);
 
-    /// The value had an incorrect type.
-    InvalidType(de::Type),
-
-    /// The value had an invalid length.
-    InvalidLength(usize),
-
-    /// The value is invalid and cannot be deserialized.
-    #[cfg(any(feature = "std", feature = "collections"))]
-    InvalidValue(String),
-    /// The value is invalid and cannot be deserialized.
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    InvalidValue(&'static str),
-
-    /// EOF while deserializing a value.
-    EndOfStream,
-
-    /// Unknown variant in enum.
-    #[cfg(any(feature = "std", feature = "collections"))]
-    UnknownVariant(String),
-    /// Unknown variant in enum.
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    UnknownVariant(&'static str),
-
-    /// Unknown field in struct.
-    #[cfg(any(feature = "std", feature = "collections"))]
-    UnknownField(String),
-    /// Unknown field in struct.
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    UnknownField(&'static str),
-
-    /// Struct is missing a field.
-    MissingField(&'static str),
-}
+#[cfg(any(feature = "std", feature = "collections"))]
+type ErrorImpl = Box<str>;
+#[cfg(not(any(feature = "std", feature = "collections")))]
+type ErrorImpl = ();
 
 impl de::Error for Error {
     #[cfg(any(feature = "std", feature = "collections"))]
-    fn custom<T: Into<String>>(msg: T) -> Self { Error::Custom(msg.into()) }
+    fn custom<T: Display>(msg: T) -> Self {
+        Error(msg.to_string().into_boxed_str())
+    }
 
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    fn custom<T: Into<&'static str>>(msg: T) -> Self { Error::Custom(msg.into()) }
-
-    fn end_of_stream() -> Self { Error::EndOfStream }
-    fn invalid_type(ty: de::Type) -> Self { Error::InvalidType(ty) }
-
-    #[cfg(any(feature = "std", feature = "collections"))]
-    fn invalid_value(msg: &str) -> Self { Error::InvalidValue(msg.to_owned()) }
-
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    fn invalid_value(msg: &str) -> Self { Error::InvalidValue("invalid value") }
-
-    fn invalid_length(len: usize) -> Self { Error::InvalidLength(len) }
-
-    #[cfg(any(feature = "std", feature = "collections"))]
-    fn unknown_variant(variant: &str) -> Self { Error::UnknownVariant(String::from(variant)) }
-    #[cfg(any(feature = "std", feature = "collections"))]
-    fn unknown_field(field: &str) -> Self { Error::UnknownField(String::from(field)) }
-
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    fn unknown_variant(variant: &str) -> Self { Error::UnknownVariant("unknown variant") }
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    fn unknown_field(field: &str) -> Self { Error::UnknownField("unknown field") }
-    fn missing_field(field: &'static str) -> Self { Error::MissingField(field) }
+    #[cfg(not(any(feature = "std", feature = "collections")))]
+    fn custom<T: Display>(msg: T) -> Self {
+        Error(())
+    }
 }
 
-impl fmt::Display for Error {
+impl Display for Error {
+    #[cfg(any(feature = "std", feature = "collections"))]
     fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        match *self {
-            Error::Custom(ref s) => write!(formatter, "{}", s),
-            Error::EndOfStream => formatter.write_str("End of stream"),
-            Error::InvalidType(ty) => write!(formatter, "Invalid type, expected `{:?}`", ty),
-            Error::InvalidValue(ref value) => write!(formatter, "Invalid value: {}", value),
-            Error::InvalidLength(len) => write!(formatter, "Invalid length: {}", len),
-            Error::UnknownVariant(ref variant) => {
-                write!(formatter, "Unknown variant: {}", variant)
-            }
-            Error::UnknownField(ref field) => write!(formatter, "Unknown field: {}", field),
-            Error::MissingField(field) => write!(formatter, "Missing field: {}", field),
-        }
+        formatter.write_str(&self.0)
+    }
+
+    #[cfg(not(any(feature = "std", feature = "collections")))]
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        formatter.write_str("Serde deserialization error")
     }
 }
 
 impl error::Error for Error {
+    #[cfg(any(feature = "std", feature = "collections"))]
     fn description(&self) -> &str {
-        "Serde Deserialization Error"
+        &self.0
     }
 
-    fn cause(&self) -> Option<&error::Error> {
-        None
+    #[cfg(not(any(feature = "std", feature = "collections")))]
+    fn description(&self) -> &str {
+        "Serde deserialization error"
     }
 }
 
@@ -181,7 +130,7 @@ impl<E> de::Deserializer for UnitDeserializer<E>
     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
+        tuple_struct struct struct_field tuple enum ignored_any byte_buf
     }
 
     fn deserialize<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -223,7 +172,7 @@ macro_rules! primitive_deserializer {
                 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
+                ignored_any byte_buf
             }
 
             fn deserialize<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -288,7 +237,7 @@ impl<'a, E> de::Deserializer for StrDeserializer<'a, E>
     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
+        tuple_struct struct struct_field tuple ignored_any byte_buf
     }
 }
 
@@ -298,10 +247,10 @@ impl<'a, E> de::EnumVisitor for StrDeserializer<'a, E>
     type Error = E;
     type Variant = private::UnitOnly<E>;
 
-    fn visit_variant<T>(self) -> Result<(T, Self::Variant), Self::Error>
-        where T: de::Deserialize,
+    fn visit_variant_seed<T>(self, seed: T) -> Result<(T::Value, Self::Variant), Self::Error>
+        where T: de::DeserializeSeed,
     {
-        de::Deserialize::deserialize(self).map(private::unit_only)
+        seed.deserialize(self).map(private::unit_only)
     }
 }
 
@@ -346,7 +295,7 @@ impl<E> de::Deserializer for StringDeserializer<E>
     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
+        tuple_struct struct struct_field tuple ignored_any byte_buf
     }
 }
 
@@ -357,10 +306,10 @@ impl<'a, E> de::EnumVisitor for StringDeserializer<E>
     type Error = E;
     type Variant = private::UnitOnly<E>;
 
-    fn visit_variant<T>(self) -> Result<(T, Self::Variant), Self::Error>
-        where T: de::Deserialize,
+    fn visit_variant_seed<T>(self, seed: T) -> Result<(T::Value, Self::Variant), Self::Error>
+        where T: de::DeserializeSeed,
     {
-        de::Deserialize::deserialize(self).map(private::unit_only)
+        seed.deserialize(self).map(private::unit_only)
     }
 }
 
@@ -408,7 +357,7 @@ impl<'a, E> de::Deserializer for CowStrDeserializer<'a, E>
     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
+        tuple_struct struct struct_field tuple ignored_any byte_buf
     }
 }
 
@@ -419,10 +368,10 @@ impl<'a, E> de::EnumVisitor for CowStrDeserializer<'a, E>
     type Error = E;
     type Variant = private::UnitOnly<E>;
 
-    fn visit_variant<T>(self) -> Result<(T, Self::Variant), Self::Error>
-        where T: de::Deserialize,
+    fn visit_variant_seed<T>(self, seed: T) -> Result<(T::Value, Self::Variant), Self::Error>
+        where T: de::DeserializeSeed,
     {
-        de::Deserialize::deserialize(self).map(private::unit_only)
+        seed.deserialize(self).map(private::unit_only)
     }
 }
 
@@ -430,22 +379,37 @@ impl<'a, E> de::EnumVisitor for CowStrDeserializer<'a, E>
 
 /// A helper deserializer that deserializes a sequence.
 pub struct SeqDeserializer<I, E> {
-    iter: I,
-    len: usize,
+    iter: iter::Fuse<I>,
+    count: usize,
     marker: PhantomData<E>,
 }
 
 impl<I, E> SeqDeserializer<I, E>
-    where E: de::Error,
+    where I: Iterator,
+          E: de::Error,
 {
     /// Construct a new `SeqDeserializer<I>`.
-    pub fn new(iter: I, len: usize) -> Self {
+    pub fn new(iter: I) -> Self {
         SeqDeserializer {
-            iter: iter,
-            len: len,
+            iter: iter.fuse(),
+            count: 0,
             marker: PhantomData,
         }
     }
+
+    fn end(&mut self) -> Result<(), E> {
+        let mut remaining = 0;
+        while self.iter.next().is_some() {
+            remaining += 1;
+        }
+        if remaining == 0 {
+            Ok(())
+        } else {
+            // First argument is the number of elements in the data, second
+            // argument is the number of elements expected by the Deserialize.
+            Err(de::Error::invalid_length(self.count + remaining, &ExpectedInSeq(self.count)))
+        }
+    }
 }
 
 impl<I, T, E> de::Deserializer for SeqDeserializer<I, E>
@@ -459,17 +423,14 @@ impl<I, T, E> de::Deserializer for SeqDeserializer<I, E>
         where V: de::Visitor,
     {
         let v = try!(visitor.visit_seq(&mut self));
-        if self.len == 0 {
-            Ok(v)
-        } else {
-            Err(de::Error::invalid_length(self.len))
-        }
+        try!(self.end());
+        Ok(v)
     }
 
     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
+        tuple_struct struct struct_field tuple enum ignored_any byte_buf
     }
 }
 
@@ -480,20 +441,32 @@ impl<I, T, E> de::SeqVisitor for SeqDeserializer<I, E>
 {
     type Error = E;
 
-    fn visit<V>(&mut self) -> Result<Option<V>, Self::Error>
-        where V: de::Deserialize
+    fn visit_seed<V>(&mut self, seed: V) -> Result<Option<V::Value>, Self::Error>
+        where V: de::DeserializeSeed
     {
         match self.iter.next() {
             Some(value) => {
-                self.len -= 1;
-                de::Deserialize::deserialize(value.into_deserializer()).map(Some)
+                self.count += 1;
+                seed.deserialize(value.into_deserializer()).map(Some)
             }
             None => Ok(None),
         }
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (self.len, Some(self.len))
+        self.iter.size_hint()
+    }
+}
+
+struct ExpectedInSeq(usize);
+
+impl Expected for ExpectedInSeq {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        if self.0 == 1 {
+            write!(formatter, "1 element in sequence")
+        } else {
+            write!(formatter, "{} elements in sequence", self.0)
+        }
     }
 }
 
@@ -507,8 +480,7 @@ impl<T, E> ValueDeserializer<E> for Vec<T>
     type Deserializer = SeqDeserializer<vec::IntoIter<T>, E>;
 
     fn into_deserializer(self) -> Self::Deserializer {
-        let len = self.len();
-        SeqDeserializer::new(self.into_iter(), len)
+        SeqDeserializer::new(self.into_iter())
     }
 }
 
@@ -520,8 +492,7 @@ impl<T, E> ValueDeserializer<E> for BTreeSet<T>
     type Deserializer = SeqDeserializer<btree_set::IntoIter<T>, E>;
 
     fn into_deserializer(self) -> Self::Deserializer {
-        let len = self.len();
-        SeqDeserializer::new(self.into_iter(), len)
+        SeqDeserializer::new(self.into_iter())
     }
 }
 
@@ -533,8 +504,7 @@ impl<T, E> ValueDeserializer<E> for HashSet<T>
     type Deserializer = SeqDeserializer<hash_set::IntoIter<T>, E>;
 
     fn into_deserializer(self) -> Self::Deserializer {
-        let len = self.len();
-        SeqDeserializer::new(self.into_iter(), len)
+        SeqDeserializer::new(self.into_iter())
     }
 }
 
@@ -572,73 +542,73 @@ impl<V_, E> de::Deserializer for SeqVisitorDeserializer<V_, E>
     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
+        tuple_struct struct struct_field tuple enum ignored_any byte_buf
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 /// A helper deserializer that deserializes a map.
-pub struct MapDeserializer<I, K, V, E>
-    where I: Iterator<Item=(K, V)>,
-          K: ValueDeserializer<E>,
-          V: ValueDeserializer<E>,
+pub struct MapDeserializer<I, E>
+    where I: Iterator,
+          I::Item: private::Pair,
+          <I::Item as private::Pair>::First: ValueDeserializer<E>,
+          <I::Item as private::Pair>::Second: ValueDeserializer<E>,
           E: de::Error,
 {
-    iter: I,
-    value: Option<V>,
-    len: Option<usize>,
+    iter: iter::Fuse<I>,
+    value: Option<<I::Item as private::Pair>::Second>,
+    count: usize,
     marker: PhantomData<E>,
 }
 
-impl<I, K, V, E> MapDeserializer<I, K, V, E>
-    where I: Iterator<Item=(K, V)>,
-          K: ValueDeserializer<E>,
-          V: ValueDeserializer<E>,
+impl<I, E> MapDeserializer<I, E>
+    where I: Iterator,
+          I::Item: private::Pair,
+          <I::Item as private::Pair>::First: ValueDeserializer<E>,
+          <I::Item as private::Pair>::Second: ValueDeserializer<E>,
           E: de::Error,
 {
-    /// Construct a new `MapDeserializer<I, K, V, E>` with a specific length.
-    pub fn new(iter: I, len: usize) -> Self {
+    /// Construct a new `MapDeserializer<I, K, V, E>`.
+    pub fn new(iter: I) -> Self {
         MapDeserializer {
-            iter: iter,
+            iter: iter.fuse(),
             value: None,
-            len: Some(len),
+            count: 0,
             marker: PhantomData,
         }
     }
 
-    /// Construct a new `MapDeserializer<I, K, V, E>` that is not bounded
-    /// by a specific length and that delegates to `iter` for its size hint.
-    pub fn unbounded(iter: I) -> Self {
-        MapDeserializer {
-            iter: iter,
-            value: None,
-            len: None,
-            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;
+    fn next(&mut self) -> Option<(<I::Item as private::Pair>::First, <I::Item as private::Pair>::Second)> {
+        match self.iter.next() {
+            Some(kv) => {
+                self.count += 1;
+                Some(private::Pair::split(kv))
             }
-            (k, v)
-        })
+            None => None,
+        }
     }
 
     fn end(&mut self) -> Result<(), E> {
-        match self.len {
-            Some(len) if len > 0 => Err(de::Error::invalid_length(len)),
-            _ => Ok(())
+        let mut remaining = 0;
+        while self.iter.next().is_some() {
+            remaining += 1;
+        }
+        if remaining == 0 {
+            Ok(())
+        } else {
+            // First argument is the number of elements in the data, second
+            // argument is the number of elements expected by the Deserialize.
+            Err(de::Error::invalid_length(self.count + remaining, &ExpectedInMap(self.count)))
         }
     }
 }
 
-impl<I, K, V, E> de::Deserializer for MapDeserializer<I, K, V, E>
-    where I: Iterator<Item=(K, V)>,
-          K: ValueDeserializer<E>,
-          V: ValueDeserializer<E>,
+impl<I, E> de::Deserializer for MapDeserializer<I, E>
+    where I: Iterator,
+          I::Item: private::Pair,
+          <I::Item as private::Pair>::First: ValueDeserializer<E>,
+          <I::Item as private::Pair>::Second: ValueDeserializer<E>,
           E: de::Error,
 {
     type Error = E;
@@ -659,67 +629,58 @@ impl<I, K, V, E> de::Deserializer for MapDeserializer<I, K, V, E>
         Ok(value)
     }
 
-    fn deserialize_seq_fixed_size<V_>(mut self, len: usize, visitor: V_) -> Result<V_::Value, Self::Error>
+    fn deserialize_seq_fixed_size<V_>(self, _len: usize, visitor: V_) -> Result<V_::Value, Self::Error>
         where V_: de::Visitor,
     {
-        match self.len {
-            Some(map_len) if map_len != len => Err(de::Error::invalid_length(len)),
-            _ => {
-                let value = try!(visitor.visit_seq(&mut self));
-                try!(self.end());
-                Ok(value)
-            }
-        }
+        self.deserialize_seq(visitor)
     }
 
     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
+        struct_field tuple enum ignored_any byte_buf
     }
 }
 
-impl<I, K, V, E> de::MapVisitor for MapDeserializer<I, K, V, E>
-    where I: Iterator<Item=(K, V)>,
-          K: ValueDeserializer<E>,
-          V: ValueDeserializer<E>,
+impl<I, E> de::MapVisitor for MapDeserializer<I, E>
+    where I: Iterator,
+          I::Item: private::Pair,
+          <I::Item as private::Pair>::First: ValueDeserializer<E>,
+          <I::Item as private::Pair>::Second: ValueDeserializer<E>,
           E: de::Error,
 {
     type Error = E;
 
-    fn visit_key<T>(&mut self) -> Result<Option<T>, Self::Error>
-        where T: de::Deserialize,
+    fn visit_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+        where T: de::DeserializeSeed,
     {
         match self.next() {
             Some((key, value)) => {
                 self.value = Some(value);
-                de::Deserialize::deserialize(key.into_deserializer()).map(Some)
+                seed.deserialize(key.into_deserializer()).map(Some)
             }
             None => Ok(None),
         }
     }
 
-    fn visit_value<T>(&mut self) -> Result<T, Self::Error>
-        where T: de::Deserialize,
+    fn visit_value_seed<T>(&mut self, seed: T) -> Result<T::Value, Self::Error>
+        where T: de::DeserializeSeed,
     {
-        match self.value.take() {
-            Some(value) => {
-                de::Deserialize::deserialize(value.into_deserializer())
-            }
-            None => {
-                Err(de::Error::end_of_stream())
-            }
-        }
+        let value = self.value.take();
+        // Panic because this indicates a bug in the program rather than an
+        // expected failure.
+        let value = value.expect("MapVisitor::visit_value called before visit_key");
+        seed.deserialize(value.into_deserializer())
     }
 
-    fn visit<TK, TV>(&mut self) -> Result<Option<(TK, TV)>, Self::Error>
-        where TK: de::Deserialize,
-              TV: de::Deserialize
+    fn visit_seed<TK, TV>(&mut self, kseed: TK, vseed: TV) -> Result<Option<(TK::Value, TV::Value)>, Self::Error>
+        where TK: de::DeserializeSeed,
+              TV: de::DeserializeSeed
     {
         match self.next() {
             Some((key, value)) => {
-                let key = try!(de::Deserialize::deserialize(key.into_deserializer()));
-                let value = try!(de::Deserialize::deserialize(value.into_deserializer()));
+                let key = try!(kseed.deserialize(key.into_deserializer()));
+                let value = try!(vseed.deserialize(value.into_deserializer()));
                 Ok(Some((key, value)))
             }
             None => Ok(None)
@@ -727,34 +688,33 @@ impl<I, K, V, E> de::MapVisitor for MapDeserializer<I, K, V, E>
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        self.len.map_or_else(
-            || self.iter.size_hint(),
-            |len| (len, Some(len)))
+        self.iter.size_hint()
     }
 }
 
-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>,
+impl<I, E> de::SeqVisitor for MapDeserializer<I, E>
+    where I: Iterator,
+          I::Item: private::Pair,
+          <I::Item as private::Pair>::First: ValueDeserializer<E>,
+          <I::Item as private::Pair>::Second: ValueDeserializer<E>,
           E: de::Error,
 {
     type Error = E;
 
-    fn visit<T>(&mut self) -> Result<Option<T>, Self::Error>
-        where T: de::Deserialize,
+    fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+        where T: de::DeserializeSeed,
     {
         match self.next() {
             Some((k, v)) => {
                 let de = PairDeserializer(k, v, PhantomData);
-                de::Deserialize::deserialize(de).map(Some)
+                seed.deserialize(de).map(Some)
             }
             None => Ok(None),
         }
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        de::MapVisitor::size_hint(self)
+        self.iter.size_hint()
     }
 }
 
@@ -772,7 +732,7 @@ impl<A, B, E> de::Deserializer for PairDeserializer<A, B, 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
+        struct_field tuple enum ignored_any byte_buf
     }
 
     fn deserialize<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -789,7 +749,10 @@ impl<A, B, E> de::Deserializer for PairDeserializer<A, B, E>
         if pair_visitor.1.is_none() {
             Ok(pair)
         } else {
-            Err(de::Error::invalid_length(pair_visitor.size_hint().0))
+            let remaining = pair_visitor.size_hint().0;
+            // First argument is the number of elements in the data, second
+            // argument is the number of elements expected by the Deserialize.
+            Err(de::Error::invalid_length(2, &ExpectedInSeq(2 - remaining)))
         }
     }
 
@@ -799,7 +762,9 @@ impl<A, B, E> de::Deserializer for PairDeserializer<A, B, E>
         if len == 2 {
             self.deserialize_seq(visitor)
         } else {
-            Err(de::Error::invalid_length(len))
+            // First argument is the number of elements in the data, second
+            // argument is the number of elements expected by the Deserialize.
+            Err(de::Error::invalid_length(2, &ExpectedInSeq(len)))
         }
     }
 }
@@ -813,13 +778,13 @@ impl<A, B, E> de::SeqVisitor for PairVisitor<A, B, E>
 {
     type Error = E;
 
-    fn visit<T>(&mut self) -> Result<Option<T>, Self::Error>
-        where T: de::Deserialize,
+    fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+        where T: de::DeserializeSeed,
     {
         if let Some(k) = self.0.take() {
-            de::Deserialize::deserialize(k.into_deserializer()).map(Some)
+            seed.deserialize(k.into_deserializer()).map(Some)
         } else if let Some(v) = self.1.take() {
-            de::Deserialize::deserialize(v.into_deserializer()).map(Some)
+            seed.deserialize(v.into_deserializer()).map(Some)
         } else {
             Ok(None)
         }
@@ -837,6 +802,18 @@ impl<A, B, E> de::SeqVisitor for PairVisitor<A, B, E>
     }
 }
 
+struct ExpectedInMap(usize);
+
+impl Expected for ExpectedInMap {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        if self.0 == 1 {
+            write!(formatter, "1 element in map")
+        } else {
+            write!(formatter, "{} elements in map", self.0)
+        }
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 #[cfg(any(feature = "std", feature = "collections"))]
@@ -845,11 +822,10 @@ impl<K, V, E> ValueDeserializer<E> for BTreeMap<K, V>
           V: ValueDeserializer<E>,
           E: de::Error,
 {
-    type Deserializer = MapDeserializer<btree_map::IntoIter<K, V>, K, V, E>;
+    type Deserializer = MapDeserializer<btree_map::IntoIter<K, V>, E>;
 
     fn into_deserializer(self) -> Self::Deserializer {
-        let len = self.len();
-        MapDeserializer::new(self.into_iter(), len)
+        MapDeserializer::new(self.into_iter())
     }
 }
 
@@ -859,11 +835,10 @@ impl<K, V, E> ValueDeserializer<E> for HashMap<K, V>
           V: ValueDeserializer<E>,
           E: de::Error,
 {
-    type Deserializer = MapDeserializer<hash_map::IntoIter<K, V>, K, V, E>;
+    type Deserializer = MapDeserializer<hash_map::IntoIter<K, V>, E>;
 
     fn into_deserializer(self) -> Self::Deserializer {
-        let len = self.len();
-        MapDeserializer::new(self.into_iter(), len)
+        MapDeserializer::new(self.into_iter())
     }
 }
 
@@ -901,7 +876,7 @@ impl<V_, E> de::Deserializer for MapVisitorDeserializer<V_, E>
     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
+        tuple_struct struct struct_field tuple enum ignored_any byte_buf
     }
 }
 
@@ -934,7 +909,7 @@ impl<'a, E> de::Deserializer for BytesDeserializer<'a, E>
     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
+        tuple_struct struct struct_field tuple enum ignored_any byte_buf
     }
 }
 
@@ -970,14 +945,14 @@ impl<E> de::Deserializer for ByteBufDeserializer<E>
     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
+        tuple_struct struct struct_field tuple enum ignored_any byte_buf
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 mod private {
-    use de;
+    use de::{self, Unexpected};
     use core::marker::PhantomData;
 
     pub struct UnitOnly<E>(PhantomData<E>);
@@ -995,10 +970,10 @@ mod private {
             Ok(())
         }
 
-        fn visit_newtype<T>(self) -> Result<T, Self::Error>
-            where T: de::Deserialize,
+        fn visit_newtype_seed<T>(self, _seed: T) -> Result<T::Value, Self::Error>
+            where T: de::DeserializeSeed,
         {
-            Err(de::Error::invalid_type(de::Type::NewtypeVariant))
+            Err(de::Error::invalid_type(Unexpected::UnitVariant, &"newtype variant"))
         }
 
         fn visit_tuple<V>(self,
@@ -1006,7 +981,7 @@ mod private {
                         _visitor: V) -> Result<V::Value, Self::Error>
             where V: de::Visitor
         {
-            Err(de::Error::invalid_type(de::Type::TupleVariant))
+            Err(de::Error::invalid_type(Unexpected::UnitVariant, &"tuple variant"))
         }
 
         fn visit_struct<V>(self,
@@ -1014,7 +989,21 @@ mod private {
                         _visitor: V) -> Result<V::Value, Self::Error>
             where V: de::Visitor
         {
-            Err(de::Error::invalid_type(de::Type::StructVariant))
+            Err(de::Error::invalid_type(Unexpected::UnitVariant, &"struct variant"))
         }
     }
+
+    /// 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;
+        fn split(self) -> (Self::First, Self::Second);
+    }
+
+    impl<A, B> Pair for (A, B) {
+        type First = A;
+        type Second = B;
+        fn split(self) -> (A, B) { self }
+    }
 }

serde/src/error.rs

@@ -1,30 +1,7 @@
 //! A stand-in for `std::error`
-use core::any::TypeId;
 use core::fmt::{Debug, Display};
 
-
 /// A stand-in for `std::error::Error`, which requires no allocation.
-#[cfg(feature = "unstable")]
-pub trait Error: Debug + Display + ::core::marker::Reflect {
-    /// A short description of the error.
-    ///
-    /// The description should not contain newlines or sentence-ending
-    /// punctuation, to facilitate embedding in larger user-facing
-    /// strings.
-    fn description(&self) -> &str;
-
-    /// The lower-level cause of this error, if any.
-    fn cause(&self) -> Option<&Error> { None }
-
-    /// Get the `TypeId` of `self`
-    #[doc(hidden)]
-    fn type_id(&self) -> TypeId where Self: 'static {
-        TypeId::of::<Self>()
-    }
-}
-
-/// A stand-in for `std::error::Error`, which requires no allocation.
-#[cfg(not(feature = "unstable"))]
 pub trait Error: Debug + Display {
     /// A short description of the error.
     ///
@@ -35,10 +12,4 @@ pub trait Error: Debug + Display {
 
     /// The lower-level cause of this error, if any.
     fn cause(&self) -> Option<&Error> { None }
-
-    /// Stubbed! Returns type_id of `()`
-    #[doc(hidden)]
-    fn type_id(&self) -> TypeId where Self: 'static {
-        TypeId::of::<()>()
-    }
 }

serde/src/lib.rs

@@ -11,7 +11,7 @@
 
 #![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))]
+#![cfg_attr(feature = "unstable", feature(reflect_marker, unicode, nonzero, plugin, step_trait, zero_one, inclusive_range))]
 #![cfg_attr(feature = "alloc", feature(alloc))]
 #![cfg_attr(feature = "collections", feature(collections, enumset))]
 #![cfg_attr(feature = "clippy", plugin(clippy))]
@@ -40,11 +40,6 @@ mod core {
 pub use ser::{Serialize, Serializer};
 pub use de::{Deserialize, Deserializer};
 
-#[cfg(not(feature = "std"))]
-macro_rules! format {
-    ($s:expr, $($rest:tt)*) => ($s)
-}
-
 #[macro_use]
 mod macros;
 

serde/src/macros.rs

@@ -92,6 +92,9 @@ macro_rules! forward_to_deserialize_helper {
     (bytes) => {
         forward_to_deserialize_method!{deserialize_bytes()}
     };
+    (byte_buf) => {
+        forward_to_deserialize_method!{deserialize_byte_buf()}
+    };
     (map) => {
         forward_to_deserialize_method!{deserialize_map()}
     };

serde/src/ser/impls.rs

@@ -324,15 +324,31 @@ impl<T> Serialize for VecDeque<T>
 
 #[cfg(feature = "unstable")]
 impl<A> Serialize for ops::Range<A>
-    where A: Serialize + Clone + iter::Step + num::One,
-          for<'a> &'a A: ops::Add<&'a A, Output = A>,
+    where ops::Range<A>: ExactSizeIterator + iter::Iterator<Item = A> + Clone,
+          A: Serialize,
 {
     #[inline]
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
         where S: Serializer,
     {
-        let len = iter::Step::steps_between(&self.start, &self.end, &A::one());
-        let mut seq = try!(serializer.serialize_seq(len));
+        let mut seq = try!(serializer.serialize_seq(Some(self.len())));
+        for e in self.clone() {
+            try!(seq.serialize_element(e));
+        }
+        seq.end()
+    }
+}
+
+#[cfg(feature = "unstable")]
+impl<A> Serialize for ops::RangeInclusive<A>
+    where ops::RangeInclusive<A>: ExactSizeIterator + iter::Iterator<Item = A> + Clone,
+          A: Serialize,
+{
+    #[inline]
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where S: Serializer,
+    {
+        let mut seq = try!(serializer.serialize_seq(Some(self.len())));
         for e in self.clone() {
             try!(seq.serialize_element(e));
         }
@@ -756,7 +772,7 @@ impl Serialize for path::Path {
     {
         match self.to_str() {
             Some(s) => s.serialize(serializer),
-            None => Err(Error::invalid_value("Path contains invalid UTF-8 characters")),
+            None => Err(Error::custom("Path contains invalid UTF-8 characters")),
         }
     }
 }

serde/src/ser/mod.rs

@@ -23,6 +23,8 @@ use core::marker::PhantomData;
 #[cfg(feature = "unstable")]
 use core::cell::RefCell;
 
+use core::fmt::Display;
+
 pub mod impls;
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -31,17 +33,7 @@ pub mod impls;
 /// `Serializer` error.
 pub trait Error: Sized + error::Error {
     /// Raised when there is a general error when serializing a type.
-    #[cfg(any(feature = "std", feature = "collections"))]
-    fn custom<T: Into<String>>(msg: T) -> Self;
-
-    /// Raised when there is a general error when serializing a type.
-    #[cfg(all(not(feature = "std"), not(feature = "collections")))]
-    fn custom<T: Into<&'static str>>(msg: T) -> Self;
-
-    /// Raised when a `Serialize` was passed an incorrect value.
-    fn invalid_value(msg: &str) -> Self {
-        Error::custom(format!("invalid value: {}", msg))
-    }
+    fn custom<T: Display>(msg: T) -> Self;
 }
 
 ///////////////////////////////////////////////////////////////////////////////

serde_codegen/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_codegen"
-version = "0.9.0-rc1"
+version = "0.9.0-rc2"
 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/de.rs

@@ -200,12 +200,18 @@ fn deserialize_unit_struct(
 ) -> Tokens {
     let type_name = item_attrs.name().deserialize_name();
 
+    let expecting = format!("unit struct {}", type_ident);
+
     quote!({
         struct __Visitor;
 
         impl _serde::de::Visitor for __Visitor {
             type Value = #type_ident;
 
+            fn expecting(&self, formatter: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                formatter.write_str(#expecting)
+            }
+
             #[inline]
             fn visit_unit<__E>(self) -> ::std::result::Result<#type_ident, __E>
                 where __E: _serde::de::Error,
@@ -242,6 +248,10 @@ fn deserialize_tuple(
         Some(variant_ident) => quote!(#type_ident::#variant_ident),
         None => quote!(#type_ident),
     };
+    let expecting = match variant_ident {
+        Some(variant_ident) => format!("tuple variant {}::{}", type_ident, variant_ident),
+        None => format!("tuple struct {}", type_ident),
+    };
 
     let nfields = fields.len();
 
@@ -287,6 +297,10 @@ fn deserialize_tuple(
         impl #impl_generics _serde::de::Visitor for #visitor_ty #where_clause {
             type Value = #ty;
 
+            fn expecting(&self, formatter: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                formatter.write_str(#expecting)
+            }
+
             #visit_newtype_struct
 
             #[inline]
@@ -310,6 +324,11 @@ fn deserialize_seq(
 ) -> Tokens {
     let vars = (0..fields.len()).map(field_i as fn(_) -> _);
 
+    let deserialized_count = fields.iter()
+        .filter(|field| !field.attrs.skip_deserializing())
+        .count();
+    let expecting = format!("tuple of {} elements", deserialized_count);
+
     let mut index_in_seq = 0usize;
     let let_values = vars.clone().zip(fields)
         .map(|(var, field)| {
@@ -338,7 +357,7 @@ fn deserialize_seq(
                     let #var = match #visit {
                         Some(value) => { value },
                         None => {
-                            return Err(_serde::de::Error::invalid_length(#index_in_seq));
+                            return Err(_serde::de::Error::invalid_length(#index_in_seq, &#expecting));
                         }
                     };
                 };
@@ -413,6 +432,10 @@ fn deserialize_struct(
         Some(variant_ident) => quote!(#type_ident::#variant_ident),
         None => quote!(#type_ident),
     };
+    let expecting = match variant_ident {
+        Some(variant_ident) => format!("struct variant {}::{}", type_ident, variant_ident),
+        None => format!("struct {}", type_ident),
+    };
 
     let visit_seq = deserialize_seq(
         type_ident,
@@ -457,6 +480,10 @@ fn deserialize_struct(
         impl #impl_generics _serde::de::Visitor for #visitor_ty #where_clause {
             type Value = #ty;
 
+            fn expecting(&self, formatter: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                formatter.write_str(#expecting)
+            }
+
             #[inline]
             fn visit_seq<__V>(self, #visitor_var: __V) -> ::std::result::Result<#ty, __V::Error>
                 where __V: _serde::de::SeqVisitor
@@ -489,24 +516,27 @@ fn deserialize_item_enum(
 
     let type_name = item_attrs.name().deserialize_name();
 
-    let variant_names_idents = variants.iter()
+    let expecting = format!("enum {}", type_ident);
+
+    let variant_names_idents: Vec<_> = variants.iter()
         .enumerate()
         .filter(|&(_, variant)| !variant.attrs.skip_deserializing())
         .map(|(i, variant)| (variant.attrs.name().deserialize_name(), field_i(i)))
         .collect();
 
+    let variants_stmt = {
+        let variant_names = variant_names_idents.iter().map(|&(ref name, _)| name);
+        quote! {
+            const VARIANTS: &'static [&'static str] = &[ #(#variant_names),* ];
+        }
+    };
+
     let variant_visitor = deserialize_field_visitor(
         variant_names_idents,
         item_attrs,
         true,
     );
 
-    let variant_names = variants.iter().map(|variant| variant.attrs.name().deserialize_name());
-
-    let variants_stmt = quote! {
-        const VARIANTS: &'static [&'static str] = &[ #(#variant_names),* ];
-    };
-
     // Match arms to extract a variant from a string
     let variant_arms = variants.iter()
         .enumerate()
@@ -555,6 +585,10 @@ fn deserialize_item_enum(
         impl #impl_generics _serde::de::Visitor for #visitor_ty #where_clause {
             type Value = #ty;
 
+            fn expecting(&self, formatter: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                formatter.write_str(#expecting)
+            }
+
             fn visit_enum<__V>(self, visitor: __V) -> ::std::result::Result<#ty, __V::Error>
                 where __V: _serde::de::EnumVisitor,
             {
@@ -659,11 +693,11 @@ fn deserialize_field_visitor(
 
     let fallthrough_arm = if is_variant {
         quote! {
-            Err(_serde::de::Error::unknown_variant(value))
+            Err(_serde::de::Error::unknown_variant(value, VARIANTS))
         }
     } else if item_attrs.deny_unknown_fields() {
         quote! {
-            Err(_serde::de::Error::unknown_field(value))
+            Err(_serde::de::Error::unknown_field(value, FIELDS))
         }
     } else {
         quote! {
@@ -688,6 +722,10 @@ fn deserialize_field_visitor(
                 impl _serde::de::Visitor for __FieldVisitor {
                     type Value = __Field;
 
+                    fn expecting(&self, formatter: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                        formatter.write_str("field name")
+                    }
+
                     fn visit_str<__E>(self, value: &str) -> ::std::result::Result<__Field, __E>
                         where __E: _serde::de::Error
                     {
@@ -713,12 +751,19 @@ fn deserialize_struct_visitor(
     fields: &[Field],
     item_attrs: &attr::Item,
 ) -> (Tokens, Tokens, Tokens) {
-    let field_names_idents = fields.iter()
+    let field_names_idents: Vec<_> = fields.iter()
         .enumerate()
         .filter(|&(_, field)| !field.attrs.skip_deserializing())
         .map(|(i, field)| (field.attrs.name().deserialize_name(), field_i(i)))
         .collect();
 
+    let fields_stmt = {
+        let field_names = field_names_idents.iter().map(|&(ref name, _)| name);
+        quote! {
+            const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
+        }
+    };
+
     let field_visitor = deserialize_field_visitor(
         field_names_idents,
         item_attrs,
@@ -733,11 +778,6 @@ fn deserialize_struct_visitor(
         item_attrs,
     );
 
-    let field_names = fields.iter().map(|field| field.attrs.name().deserialize_name());
-    let fields_stmt = quote! {
-        const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
-    };
-
     (field_visitor, fields_stmt, visit_map)
 }
 
@@ -928,7 +968,7 @@ fn expr_is_missing(attrs: &attr::Field) -> Tokens {
     match attrs.deserialize_with() {
         None => {
             quote! {
-                try!(visitor.missing_field(#name))
+                try!(_serde::de::private::missing_field(#name))
             }
         }
         Some(_) => {

serde_codegen/src/ser.rs

@@ -257,10 +257,10 @@ fn serialize_variant(
     let variant_name = variant.attrs.name().serialize_name();
 
     if variant.attrs.skip_serializing() {
-        let skipped_msg = format!("The enum variant {}::{} cannot be serialized",
+        let skipped_msg = format!("the enum variant {}::{} cannot be serialized",
                                 type_ident, variant_ident);
         let skipped_err = quote! {
-            Err(_serde::ser::Error::invalid_value(#skipped_msg))
+            Err(_serde::ser::Error::custom(#skipped_msg))
         };
         let fields_pat = match variant.style {
             Style::Unit => quote!(),

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "0.9.0-rc1"
+version = "0.9.0-rc2"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -15,7 +15,7 @@ name = "serde_derive"
 proc-macro = true
 
 [dependencies.serde_codegen]
-version = "=0.9.0-rc1"
+version = "=0.9.0-rc2"
 path = "../serde_codegen"
 default-features = false
 features = ["with-syn"]
@@ -23,5 +23,5 @@ features = ["with-syn"]
 [dev-dependencies]
 compiletest_rs = "^0.2.0"
 fnv = "1.0"
-serde = { version = "0.9.0-rc1", path = "../serde" }
-serde_test = { version = "0.9.0-rc1", path = "../serde_test" }
+serde = { version = "0.9.0-rc2", path = "../serde" }
+serde_test = { version = "0.9.0-rc2", path = "../serde_test" }

serde_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_test"
-version = "0.9.0-rc1"
+version = "0.9.0-rc2"
 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 = "0.9.0-rc1", path = "../serde" }
+serde = { version = "0.9.0-rc2", path = "../serde" }

serde_test/src/de.rs

@@ -3,6 +3,7 @@ use std::iter;
 use serde::de::{
     self,
     Deserialize,
+    DeserializeSeed,
     EnumVisitor,
     MapVisitor,
     SeqVisitor,
@@ -42,7 +43,7 @@ impl<I> Deserializer<I>
                     Err(Error::UnexpectedToken(token))
                 }
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -160,6 +161,10 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
         where __V: de::Visitor {
         self.deserialize(visitor)
     }
+    fn deserialize_byte_buf<__V>(self, visitor: __V) -> Result<__V::Value, Self::Error>
+        where __V: de::Visitor {
+        self.deserialize(visitor)
+    }
     fn deserialize_ignored_any<__V>(self, visitor: __V) -> Result<__V::Value, Self::Error>
         where __V: de::Visitor {
         self.deserialize(visitor)
@@ -250,10 +255,11 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
             Some(Token::Str(v)) => visitor.visit_str(v),
             Some(Token::String(v)) => visitor.visit_string(v),
             Some(Token::Bytes(v)) => visitor.visit_bytes(v),
+            Some(Token::ByteBuf(v)) => visitor.visit_byte_buf(v),
             Some(Token::Option(false)) => visitor.visit_none(),
             Some(Token::Option(true)) => visitor.visit_some(self),
             Some(Token::Unit) => visitor.visit_unit(),
-            Some(Token::UnitStruct(name)) => visitor.visit_unit_struct(name),
+            Some(Token::UnitStruct(_name)) => visitor.visit_unit(),
             Some(Token::SeqStart(len)) => {
                 self.visit_seq(len, visitor)
             }
@@ -267,7 +273,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 self.visit_map(Some(len), visitor)
             }
             Some(token) => Err(Error::UnexpectedToken(token)),
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -290,7 +296,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 visitor.visit_none()
             }
             Some(_) => visitor.visit_some(self),
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -320,7 +326,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 let token = self.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => { return Err(Error::EndOfStream); }
+            None => { return Err(Error::EndOfTokens); }
         }
     }
 
@@ -337,7 +343,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 }
             }
             Some(_) => self.deserialize(visitor),
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -356,7 +362,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 }
             }
             Some(_) => self.deserialize(visitor),
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -371,7 +377,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 self.visit_array(len, visitor)
             }
             Some(_) => self.deserialize(visitor),
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -406,7 +412,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 self.visit_tuple_struct(len, visitor)
             }
             Some(_) => self.deserialize(visitor),
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -450,7 +456,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 }
             }
             Some(_) => self.deserialize(visitor),
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -474,7 +480,7 @@ impl<'a, I> de::Deserializer for &'a mut Deserializer<I>
                 self.visit_map(Some(fields.len()), visitor)
             }
             Some(_) => self.deserialize(visitor),
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 }
@@ -491,21 +497,21 @@ impl<'a, I> SeqVisitor for DeserializerSeqVisitor<'a, I>
 {
     type Error = Error;
 
-    fn visit<T>(&mut self) -> Result<Option<T>, Error>
-        where T: Deserialize,
+    fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Error>
+        where T: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::SeqSep) => {
                 self.de.tokens.next();
                 self.len = self.len.map(|len| len - 1);
-                Deserialize::deserialize(&mut *self.de).map(Some)
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Some(&Token::SeqEnd) => Ok(None),
             Some(_) => {
                 let token = self.de.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -527,21 +533,21 @@ impl<'a, I> SeqVisitor for DeserializerArrayVisitor<'a, I>
 {
     type Error = Error;
 
-    fn visit<T>(&mut self) -> Result<Option<T>, Error>
-        where T: Deserialize,
+    fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Error>
+        where T: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::SeqSep) => {
                 self.de.tokens.next();
                 self.len -= 1;
-                Deserialize::deserialize(&mut *self.de).map(Some)
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Some(&Token::SeqEnd) => Ok(None),
             Some(_) => {
                 let token = self.de.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -562,21 +568,21 @@ impl<'a, I> SeqVisitor for DeserializerTupleVisitor<'a, I>
 {
     type Error = Error;
 
-    fn visit<T>(&mut self) -> Result<Option<T>, Error>
-        where T: Deserialize,
+    fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Error>
+        where T: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::TupleSep) => {
                 self.de.tokens.next();
                 self.len -= 1;
-                Deserialize::deserialize(&mut *self.de).map(Some)
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Some(&Token::TupleEnd) => Ok(None),
             Some(_) => {
                 let token = self.de.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -597,21 +603,21 @@ impl<'a, I> SeqVisitor for DeserializerTupleStructVisitor<'a, I>
 {
     type Error = Error;
 
-    fn visit<T>(&mut self) -> Result<Option<T>, Error>
-        where T: Deserialize,
+    fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Error>
+        where T: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::TupleStructSep) => {
                 self.de.tokens.next();
                 self.len -= 1;
-                Deserialize::deserialize(&mut *self.de).map(Some)
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Some(&Token::TupleStructEnd) => Ok(None),
             Some(_) => {
                 let token = self.de.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -632,21 +638,21 @@ impl<'a, I> SeqVisitor for DeserializerVariantSeqVisitor<'a, I>
 {
     type Error = Error;
 
-    fn visit<T>(&mut self) -> Result<Option<T>, Error>
-        where T: Deserialize,
+    fn visit_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Error>
+        where T: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::EnumSeqSep) => {
                 self.de.tokens.next();
                 self.len = self.len.map(|len| len - 1);
-                Deserialize::deserialize(&mut *self.de).map(Some)
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Some(&Token::EnumSeqEnd) => Ok(None),
             Some(_) => {
                 let token = self.de.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -668,28 +674,28 @@ impl<'a, I> MapVisitor for DeserializerMapVisitor<'a, I>
 {
     type Error = Error;
 
-    fn visit_key<K>(&mut self) -> Result<Option<K>, Error>
-        where K: Deserialize,
+    fn visit_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Error>
+        where K: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::MapSep) => {
                 self.de.tokens.next();
                 self.len = self.len.map(|len| if len > 0 { len - 1} else { 0 });
-                Deserialize::deserialize(&mut *self.de).map(Some)
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Some(&Token::MapEnd) => Ok(None),
             Some(_) => {
                 let token = self.de.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
-    fn visit_value<V>(&mut self) -> Result<V, Error>
-        where V: Deserialize,
+    fn visit_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Error>
+        where V: DeserializeSeed,
     {
-        Deserialize::deserialize(&mut *self.de)
+        seed.deserialize(&mut *self.de)
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
@@ -710,28 +716,28 @@ impl<'a, I> MapVisitor for DeserializerStructVisitor<'a, I>
 {
     type Error = Error;
 
-    fn visit_key<K>(&mut self) -> Result<Option<K>, Error>
-        where K: Deserialize,
+    fn visit_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Error>
+        where K: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::StructSep) => {
                 self.de.tokens.next();
                 self.len = self.len.saturating_sub(1);
-                Deserialize::deserialize(&mut *self.de).map(Some)
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Some(&Token::StructEnd) => Ok(None),
             Some(_) => {
                 let token = self.de.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
-    fn visit_value<V>(&mut self) -> Result<V, Error>
-        where V: Deserialize,
+    fn visit_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Error>
+        where V: DeserializeSeed,
     {
-        Deserialize::deserialize(&mut *self.de)
+        seed.deserialize(&mut *self.de)
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
@@ -751,8 +757,8 @@ impl<'a, I> EnumVisitor for DeserializerEnumVisitor<'a, I>
     type Error = Error;
     type Variant = Self;
 
-    fn visit_variant<V>(self) -> Result<(V, Self), Error>
-        where V: Deserialize,
+    fn visit_variant_seed<V>(self, seed: V) -> Result<(V::Value, Self), Error>
+        where V: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::EnumUnit(_, v))
@@ -760,14 +766,14 @@ impl<'a, I> EnumVisitor for DeserializerEnumVisitor<'a, I>
             | Some(&Token::EnumSeqStart(_, v, _))
             | Some(&Token::EnumMapStart(_, v, _)) => {
                 let de = v.into_deserializer();
-                let value = try!(Deserialize::deserialize(de));
+                let value = try!(seed.deserialize(de));
                 Ok((value, self))
             }
             Some(_) => {
-                let value = try!(Deserialize::deserialize(&mut *self.de));
+                let value = try!(seed.deserialize(&mut *self.de));
                 Ok((value, self))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 }
@@ -786,22 +792,22 @@ impl<'a, I> VariantVisitor for DeserializerEnumVisitor<'a, I>
             Some(_) => {
                 Deserialize::deserialize(self.de)
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
-    fn visit_newtype<T>(self) -> Result<T, Self::Error>
-        where T: Deserialize,
+    fn visit_newtype_seed<T>(self, seed: T) -> Result<T::Value, Self::Error>
+        where T: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::EnumNewType(_, _)) => {
                 self.de.tokens.next();
-                Deserialize::deserialize(self.de)
+                seed.deserialize(self.de)
             }
             Some(_) => {
-                Deserialize::deserialize(self.de)
+                seed.deserialize(self.de)
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -832,7 +838,7 @@ impl<'a, I> VariantVisitor for DeserializerEnumVisitor<'a, I>
             Some(_) => {
                 de::Deserializer::deserialize(self.de, visitor)
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
@@ -863,7 +869,7 @@ impl<'a, I> VariantVisitor for DeserializerEnumVisitor<'a, I>
             Some(_) => {
                 de::Deserializer::deserialize(self.de, visitor)
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 }
@@ -880,28 +886,28 @@ impl<'a, I> MapVisitor for DeserializerVariantMapVisitor<'a, I>
 {
     type Error = Error;
 
-    fn visit_key<K>(&mut self) -> Result<Option<K>, Error>
-        where K: Deserialize,
+    fn visit_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Error>
+        where K: DeserializeSeed,
     {
         match self.de.tokens.peek() {
             Some(&Token::EnumMapSep) => {
                 self.de.tokens.next();
                 self.len = self.len.map(|len| if len > 0 { len - 1} else { 0 });
-                Deserialize::deserialize(&mut *self.de).map(Some)
+                seed.deserialize(&mut *self.de).map(Some)
             }
             Some(&Token::EnumMapEnd) => Ok(None),
             Some(_) => {
                 let token = self.de.tokens.next().unwrap();
                 Err(Error::UnexpectedToken(token))
             }
-            None => Err(Error::EndOfStream),
+            None => Err(Error::EndOfTokens),
         }
     }
 
-    fn visit_value<V>(&mut self) -> Result<V, Error>
-        where V: Deserialize,
+    fn visit_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Error>
+        where V: DeserializeSeed,
     {
-        Deserialize::deserialize(&mut *self.de)
+        seed.deserialize(&mut *self.de)
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {

serde_test/src/error.rs

@@ -1,4 +1,5 @@
-use std::{error, fmt};
+use std::error;
+use std::fmt::{self, Display};
 
 use serde::{ser, de};
 
@@ -6,82 +7,42 @@ use token::Token;
 
 #[derive(Clone, PartialEq, Debug)]
 pub enum Error {
-    // Shared
-    Custom(String),
-    InvalidValue(String),
-
-    // De
-    EndOfStream,
-    InvalidType(de::Type),
-    InvalidLength(usize),
-    UnknownVariant(String),
-    UnknownField(String),
-    MissingField(&'static str),
-    DuplicateField(&'static str),
+    Message(String),
     InvalidName(&'static str),
     UnexpectedToken(Token<'static>),
+    EndOfTokens,
 }
 
 impl ser::Error for Error {
-    fn custom<T: Into<String>>(msg: T) -> Error {
-        Error::Custom(msg.into())
-    }
-
-    fn invalid_value(msg: &str) -> Error {
-        Error::InvalidValue(msg.to_owned())
+    fn custom<T: Display>(msg: T) -> Error {
+        Error::Message(msg.to_string())
     }
 }
 
 impl de::Error for Error {
-    fn custom<T: Into<String>>(msg: T) -> Error {
-        Error::Custom(msg.into())
-    }
-
-    fn end_of_stream() -> Error {
-        Error::EndOfStream
-    }
-
-    fn invalid_type(ty: de::Type) -> Error {
-        Error::InvalidType(ty)
-    }
-
-    fn invalid_value(msg: &str) -> Error {
-        Error::InvalidValue(msg.to_owned())
-    }
-
-    fn invalid_length(len: usize) -> Error {
-        Error::InvalidLength(len)
-    }
-
-    fn unknown_variant(variant: &str) -> Error {
-        Error::UnknownVariant(variant.to_owned())
-    }
-
-    fn unknown_field(field: &str) -> Error {
-        Error::UnknownField(field.to_owned())
-    }
-
-    fn missing_field(field: &'static str) -> Error {
-        Error::MissingField(field)
-    }
-
-    fn duplicate_field(field: &'static str) -> Error {
-        Error::DuplicateField(field)
+    fn custom<T: Display>(msg: T) -> Error {
+        Error::Message(msg.to_string())
     }
 }
 
 impl fmt::Display for Error {
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        formatter.write_str(format!("{:?}", self).as_ref())
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Error::Message(ref msg) => formatter.write_str(msg),
+            Error::InvalidName(name) => write!(formatter, "invalid name `{}`", name),
+            Error::UnexpectedToken(_) => formatter.write_str("unexpected token"),
+            Error::EndOfTokens => formatter.write_str("end of tokens"),
+        }
     }
 }
 
 impl error::Error for Error {
     fn description(&self) -> &str {
-        "Serde Error"
-    }
-
-    fn cause(&self) -> Option<&error::Error> {
-        None
+        match *self {
+            Error::Message(ref msg) => msg,
+            Error::InvalidName(_) => "invalid name",
+            Error::UnexpectedToken(_) => "unexpected token",
+            Error::EndOfTokens => "end of tokens",
+        }
     }
 }

serde_test/src/token.rs

@@ -17,6 +17,7 @@ pub enum Token<'a> {
     Str(&'a str),
     String(String),
     Bytes(&'a [u8]),
+    ByteBuf(Vec<u8>),
 
     Option(bool),
 

testing/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_testing"
-version = "0.9.0-rc1"
+version = "0.9.0-rc2"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "A generic serialization/deserialization framework"

testing/tests/test_annotations.rs

@@ -145,7 +145,7 @@ fn test_default_enum() {
     assert_de_tokens(
         &DefaultEnum::Struct { a1: 1, a2: 2, a3: 3, a4: 0, a5: 123 },
         &[
-            Token::EnumMapStart("DefaultEnum", "Struct", 5),
+            Token::EnumMapStart("DefaultEnum", "Struct", 3),
 
             Token::EnumMapSep,
             Token::Str("a1"),
@@ -174,7 +174,7 @@ fn test_default_enum() {
     assert_de_tokens(
         &DefaultEnum::Struct { a1: 1, a2: 0, a3: 123, a4: 0, a5: 123 },
         &[
-            Token::EnumMapStart("DefaultEnum", "Struct", 5),
+            Token::EnumMapStart("DefaultEnum", "Struct", 3),
 
             Token::EnumMapSep,
             Token::Str("a1"),
@@ -343,7 +343,7 @@ fn test_ignore_unknown() {
             Token::StructSep,
             Token::Str("whoops"),
         ],
-        Error::UnknownField("whoops".to_owned())
+        Error::Message("unknown field `whoops`, expected `a1`".to_owned())
     );
 }
 
@@ -905,7 +905,7 @@ fn test_missing_renamed_field_struct() {
 
             Token::StructEnd,
         ],
-        Error::MissingField("a3"),
+        Error::Message("missing field `a3`".to_owned()),
     );
 
     assert_de_tokens_error::<RenameStructSerializeDeserialize>(
@@ -918,7 +918,7 @@ fn test_missing_renamed_field_struct() {
 
             Token::StructEnd,
         ],
-        Error::MissingField("a5"),
+        Error::Message("missing field `a5`".to_owned()),
     );
 }
 
@@ -930,7 +930,7 @@ fn test_missing_renamed_field_enum() {
 
             Token::EnumMapEnd,
         ],
-        Error::MissingField("b"),
+        Error::Message("missing field `b`".to_owned()),
     );
 
     assert_de_tokens_error::<RenameEnumSerializeDeserialize<i8>>(
@@ -943,7 +943,7 @@ fn test_missing_renamed_field_enum() {
 
             Token::EnumMapEnd,
         ],
-        Error::MissingField("d"),
+        Error::Message("missing field `d`".to_owned()),
     );
 }
 
@@ -962,7 +962,7 @@ fn test_invalid_length_enum() {
                 Token::I32(1),
             Token::EnumSeqEnd,
         ],
-        Error::InvalidLength(1),
+        Error::Message("invalid length 1, expected tuple of 3 elements".to_owned()),
     );
     assert_de_tokens_error::<InvalidLengthEnum>(
         &[
@@ -971,6 +971,6 @@ fn test_invalid_length_enum() {
                 Token::I32(1),
             Token::EnumSeqEnd,
         ],
-        Error::InvalidLength(1),
+        Error::Message("invalid length 1, expected tuple of 2 elements".to_owned()),
     );
 }

testing/tests/test_bytes.rs

@@ -15,6 +15,7 @@ fn test_bytes() {
 fn test_byte_buf() {
     let empty = ByteBuf::new();
     assert_tokens(&empty, &[Token::Bytes(b"")]);
+    assert_de_tokens(&empty, &[Token::ByteBuf(Vec::new())]);
     assert_de_tokens(&empty, &[Token::Str("")]);
     assert_de_tokens(&empty, &[Token::String(String::new())]);
     assert_de_tokens(&empty, &[
@@ -28,6 +29,7 @@ fn test_byte_buf() {
 
     let buf = ByteBuf::from(vec![65, 66, 67]);
     assert_tokens(&buf, &[Token::Bytes(b"ABC")]);
+    assert_de_tokens(&buf, &[Token::ByteBuf(vec![65, 66, 67])]);
     assert_de_tokens(&buf, &[Token::Str("ABC")]);
     assert_de_tokens(&buf, &[Token::String("ABC".to_owned())]);
     assert_de_tokens(&buf, &[

testing/tests/test_de.rs

@@ -3,7 +3,7 @@ use std::net;
 use std::path::PathBuf;
 use std::time::Duration;
 
-use serde::de::{Deserialize, Type};
+use serde::Deserialize;
 
 extern crate fnv;
 use self::fnv::FnvHasher;
@@ -849,7 +849,7 @@ declare_error_tests! {
                 Token::StructSep,
                 Token::Str("d"),
         ],
-        Error::UnknownField("d".to_owned()),
+        Error::Message("unknown field `d`, expected `a`".to_owned()),
     }
     test_skipped_field_is_unknown<StructDenyUnknown> {
         &[
@@ -857,7 +857,7 @@ declare_error_tests! {
                 Token::StructSep,
                 Token::Str("b"),
         ],
-        Error::UnknownField("b".to_owned()),
+        Error::Message("unknown field `b`, expected `a`".to_owned()),
     }
     test_skip_all_deny_unknown<StructSkipAllDenyUnknown> {
         &[
@@ -865,25 +865,25 @@ declare_error_tests! {
                 Token::StructSep,
                 Token::Str("a"),
         ],
-        Error::UnknownField("a".to_owned()),
+        Error::Message("unknown field `a`, there are no fields".to_owned()),
     }
     test_unknown_variant<Enum> {
         &[
             Token::EnumUnit("Enum", "Foo"),
         ],
-        Error::UnknownVariant("Foo".to_owned()),
+        Error::Message("unknown variant `Foo`, expected one of `Unit`, `Simple`, `Seq`, `Map`".to_owned()),
     }
     test_enum_skipped_variant<Enum> {
         &[
             Token::EnumUnit("Enum", "Skipped"),
         ],
-        Error::UnknownVariant("Skipped".to_owned()),
+        Error::Message("unknown variant `Skipped`, expected one of `Unit`, `Simple`, `Seq`, `Map`".to_owned()),
     }
     test_enum_skip_all<EnumSkipAll> {
         &[
             Token::EnumUnit("EnumSkipAll", "Skipped"),
         ],
-        Error::UnknownVariant("Skipped".to_owned()),
+        Error::Message("unknown variant `Skipped`, there are no variants".to_owned()),
     }
     test_struct_seq_too_long<Struct> {
         &[
@@ -904,7 +904,7 @@ declare_error_tests! {
                 Token::MapSep,
                 Token::Str("a"),
         ],
-        Error::DuplicateField("a"),
+        Error::Message("duplicate field `a`".to_owned()),
     }
     test_duplicate_field_enum<Enum> {
         &[
@@ -916,7 +916,7 @@ declare_error_tests! {
                 Token::EnumMapSep,
                 Token::Str("a"),
         ],
-        Error::DuplicateField("a"),
+        Error::Message("duplicate field `a`".to_owned()),
     }
     test_enum_unit_usize<Enum> {
         &[
@@ -924,7 +924,7 @@ declare_error_tests! {
             Token::Usize(0),
             Token::Unit,
         ],
-        Error::InvalidType(Type::U64),
+        Error::Message("invalid type: integer `0`, expected field name".into()),
     }
     test_enum_unit_bytes<Enum> {
         &[
@@ -932,6 +932,6 @@ declare_error_tests! {
             Token::Bytes(b"Unit"),
             Token::Unit,
         ],
-        Error::InvalidType(Type::Bytes),
+        Error::Message("invalid type: byte array, expected field name".into()),
     }
 }

testing/tests/test_ser.rs

@@ -432,7 +432,7 @@ fn test_cannot_serialize_paths() {
     assert_ser_tokens_error(
         &Path::new(path),
         &[],
-        Error::InvalidValue("Path contains invalid UTF-8 characters".to_owned()));
+        Error::Message("Path contains invalid UTF-8 characters".to_owned()));
 
     let mut path_buf = PathBuf::new();
     path_buf.push(path);
@@ -440,7 +440,7 @@ fn test_cannot_serialize_paths() {
     assert_ser_tokens_error(
         &path_buf,
         &[],
-        Error::InvalidValue("Path contains invalid UTF-8 characters".to_owned()));
+        Error::Message("Path contains invalid UTF-8 characters".to_owned()));
 }
 
 #[test]
@@ -448,17 +448,17 @@ fn test_enum_skipped() {
     assert_ser_tokens_error(
         &Enum::SkippedUnit,
         &[],
-        Error::InvalidValue("The enum variant Enum::SkippedUnit cannot be serialized".to_owned()));
+        Error::Message("the enum variant Enum::SkippedUnit cannot be serialized".to_owned()));
     assert_ser_tokens_error(
         &Enum::SkippedOne(42),
         &[],
-        Error::InvalidValue("The enum variant Enum::SkippedOne cannot be serialized".to_owned()));
+        Error::Message("the enum variant Enum::SkippedOne cannot be serialized".to_owned()));
     assert_ser_tokens_error(
         &Enum::SkippedSeq(1, 2),
         &[],
-        Error::InvalidValue("The enum variant Enum::SkippedSeq cannot be serialized".to_owned()));
+        Error::Message("the enum variant Enum::SkippedSeq cannot be serialized".to_owned()));
     assert_ser_tokens_error(
         &Enum::SkippedMap { _a: 1, _b: 2 },
         &[],
-        Error::InvalidValue("The enum variant Enum::SkippedMap cannot be serialized".to_owned()));
+        Error::Message("the enum variant Enum::SkippedMap cannot be serialized".to_owned()));
 }