Release 1.0.66

CI builders for all versions mentioned in the build script

.github/ISSUE_TEMPLATE/1-problem.md

@@ -0,0 +1,7 @@
+---
+name: Problem
+about: Something does not seem right
+
+---
+
+

.github/ISSUE_TEMPLATE/2-suggestion.md

@@ -0,0 +1,7 @@
+---
+name: Suggestion
+about: Share how Serde could support your use case better
+
+---
+
+

.github/ISSUE_TEMPLATE/3-documentation.md

@@ -0,0 +1,7 @@
+---
+name: Documentation
+about: Certainly there is room for improvement
+
+---
+
+

.github/ISSUE_TEMPLATE/4-discussion.md

@@ -0,0 +1,7 @@
+---
+name: Help or discussion
+about: This is the right place
+
+---
+
+

.github/ISSUE_TEMPLATE/5-other.md

@@ -0,0 +1,7 @@
+---
+name: Anything else!
+about: Whatever is on your mind
+
+---
+
+

.travis.yml

@@ -4,11 +4,15 @@ cache: cargo
 
 # run builds for all the trains (and more)
 rust:
-  - 1.13.0
-  - 1.15.0
   - stable
   - beta
   - nightly
+  - 1.13.0
+  - 1.15.0
+  - 1.20.0
+  - 1.21.0
+  - 1.25.0
+  - 1.26.0
 
 matrix:
   include:

README.md

@@ -25,7 +25,7 @@ You may be looking for:
 <details>
 <summary>
 Click to show Cargo.toml.
-<a href="http://play.integer32.com/?gist=9003c5b88c1f4989941925d7190c6eec" target="_blank">Run this code in the playground.</a>
+<a href="https://play.rust-lang.org/?gist=9003c5b88c1f4989941925d7190c6eec" target="_blank">Run this code in the playground.</a>
 </summary>
 
 ```toml

crates-io.md

@@ -0,0 +1,55 @@
+<!-- Serde readme rendered on crates.io -->
+
+**Serde is a framework for *ser*ializing and *de*serializing Rust data structures efficiently and generically.**
+
+---
+
+You may be looking for:
+
+- [An overview of Serde](https://serde.rs/)
+- [Data formats supported by Serde](https://serde.rs/#data-formats)
+- [Setting up `#[derive(Serialize, Deserialize)]`](https://serde.rs/codegen.html)
+- [Examples](https://serde.rs/examples.html)
+- [API documentation](https://docs.serde.rs/serde/)
+- [Release notes](https://github.com/serde-rs/serde/releases)
+
+## Serde in action
+
+```rust
+#[macro_use]
+extern crate serde_derive;
+
+extern crate serde;
+extern crate serde_json;
+
+#[derive(Serialize, Deserialize, Debug)]
+struct Point {
+    x: i32,
+    y: i32,
+}
+
+fn main() {
+    let point = Point { x: 1, y: 2 };
+
+    // Convert the Point to a JSON string.
+    let serialized = serde_json::to_string(&point).unwrap();
+
+    // Prints serialized = {"x":1,"y":2}
+    println!("serialized = {}", serialized);
+
+    // Convert the JSON string back to a Point.
+    let deserialized: Point = serde_json::from_str(&serialized).unwrap();
+
+    // Prints deserialized = Point { x: 1, y: 2 }
+    println!("deserialized = {:?}", deserialized);
+}
+```
+
+## Getting help
+
+Serde developers live in the #serde channel on
+[`irc.mozilla.org`](https://wiki.mozilla.org/IRC). The #rust channel is also a
+good resource with generally faster response time but less specific knowledge
+about Serde. If IRC is not your thing or you don't get a good response, we are
+happy to respond to [GitHub issues](https://github.com/serde-rs/serde/issues/new)
+as well.

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.45" # remember to update html_root_url
+version = "1.0.66" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -9,8 +9,9 @@ repository = "https://github.com/serde-rs/serde"
 documentation = "https://docs.serde.rs/serde/"
 keywords = ["serde", "serialization", "no_std"]
 categories = ["encoding"]
-readme = "README.md"
-include = ["Cargo.toml", "src/**/*.rs", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+readme = "crates-io.md"
+include = ["Cargo.toml", "build.rs", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+build = "build.rs"
 
 [badges]
 travis-ci = { repository = "serde-rs/serde" }
@@ -28,14 +29,30 @@ serde_derive = { version = "1.0", path = "../serde_derive" }
 [features]
 default = ["std"]
 
-# Re-export the derive(Serialize, Deserialize) macros. This is specifically
-# intended for library crates that provide optional Serde impls behind a Cargo
-# cfg of their own. All other crates should depend on serde_derive directly.
+# Re-export the derive(Serialize, Deserialize) macros. This is intended for
+# library crates that provide optional Serde impls behind a Cargo cfg of their
+# own.
+#
+# Mainly this is a workaround for limitations associated with
+# rust-lang/cargo#1286 in which a library crate cannot use one "serde" cfg in
+# Cargo to enable dependencies on both serde and serde_derive crates.
+#
+# The recommended way to provide optional Serde support that requires derive is
+# as follows. In particular, please do not name your library's Serde feature
+# anything other than "serde".
+#
+#     [dependencies]
+#     serde = { version = "1.0", optional = true, features = ["derive"] }
+#
+# Within the library, these optional Serde derives would be written like this.
+#
+#     #[cfg(feature = "serde")]
+#     #[macro_use]
+#     extern crate serde;
+#
+#     #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#     struct ...
 #
-# Please refer to the long comment above the line `pub use serde_derive::*` in
-# src/lib.rs before enabling this feature. If you think you need this feature
-# and your use case does not precisely match the one described in the comment,
-# please open an issue to let us know about your use case.
 derive = ["serde_derive"]
 
 # Provide impls for common standard library types like Vec<T> and HashMap<K, V>.
@@ -61,8 +78,3 @@ alloc = ["unstable"]
 # does not preserve identity and may result in multiple copies of the same data.
 # Be sure that this is what you want before enabling this feature.
 rc = []
-
-# Get serde_derive picked up by the Integer 32 playground. Not public API.
-#
-#    http://play.integer32.com/
-playground = ["serde_derive"]

serde/build.rs

@@ -0,0 +1,78 @@
+use std::env;
+use std::process::Command;
+use std::str::{self, FromStr};
+
+// The rustc-cfg strings below are *not* public API. Please let us know by
+// opening a GitHub issue if your build environment requires some way to enable
+// these cfgs other than by executing our build script.
+fn main() {
+    let minor = match rustc_minor_version() {
+        Some(minor) => minor,
+        None => return,
+    };
+
+    // CString::into_boxed_c_str stabilized in Rust 1.20:
+    // https://doc.rust-lang.org/std/ffi/struct.CString.html#method.into_boxed_c_str
+    if minor >= 20 {
+        println!("cargo:rustc-cfg=de_boxed_c_str");
+    }
+
+    // From<Box<T>> for Rc<T> / Arc<T> stabilized in Rust 1.21:
+    // https://doc.rust-lang.org/std/rc/struct.Rc.html#impl-From<Box<T>>
+    // https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-From<Box<T>>
+    if minor >= 21 {
+        println!("cargo:rustc-cfg=de_rc_dst");
+    }
+
+    // Duration available in core since Rust 1.25:
+    // https://blog.rust-lang.org/2018/03/29/Rust-1.25.html#library-stabilizations
+    if minor >= 25 {
+        println!("cargo:rustc-cfg=core_duration");
+    }
+
+    // 128-bit integers stabilized in Rust 1.26:
+    // https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
+    if minor >= 26 {
+        println!("cargo:rustc-cfg=integer128");
+    }
+
+    // Non-zero integers stabilized in Rust 1.28:
+    // https://github.com/rust-lang/rust/pull/50808
+    if minor >= 28 {
+        println!("cargo:rustc-cfg=num_nonzero");
+    }
+}
+
+fn rustc_minor_version() -> Option<u32> {
+    let rustc = match env::var_os("RUSTC") {
+        Some(rustc) => rustc,
+        None => return None,
+    };
+
+    let output = match Command::new(rustc).arg("--version").output() {
+        Ok(output) => output,
+        Err(_) => return None,
+    };
+
+    let version = match str::from_utf8(&output.stdout) {
+        Ok(version) => version,
+        Err(_) => return None,
+    };
+
+    // Temporary workaround to support the old 1.26-dev compiler on docs.rs.
+    if version.contains("0eb87c9bf") {
+        return Some(25);
+    }
+
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return None;
+    }
+
+    let next = match pieces.next() {
+        Some(next) => next,
+        None => return None,
+    };
+
+    u32::from_str(next).ok()
+}

serde/crates-io.md

@@ -0,0 +1 @@
+../crates-io.md

serde/src/de/from_primitive.rs

@@ -39,12 +39,10 @@ macro_rules! uint_to {
 }
 
 pub trait FromPrimitive: Sized {
-    fn from_isize(n: isize) -> Option<Self>;
     fn from_i8(n: i8) -> Option<Self>;
     fn from_i16(n: i16) -> Option<Self>;
     fn from_i32(n: i32) -> Option<Self>;
     fn from_i64(n: i64) -> Option<Self>;
-    fn from_usize(n: usize) -> Option<Self>;
     fn from_u8(n: u8) -> Option<Self>;
     fn from_u16(n: u16) -> Option<Self>;
     fn from_u32(n: u32) -> Option<Self>;
@@ -54,10 +52,6 @@ pub trait FromPrimitive: Sized {
 macro_rules! impl_from_primitive_for_int {
     ($t:ident) => {
         impl FromPrimitive for $t {
-            #[inline]
-            fn from_isize(n: isize) -> Option<Self> {
-                int_to_int!($t, n)
-            }
             #[inline]
             fn from_i8(n: i8) -> Option<Self> {
                 int_to_int!($t, n)
@@ -75,10 +69,6 @@ macro_rules! impl_from_primitive_for_int {
                 int_to_int!($t, n)
             }
             #[inline]
-            fn from_usize(n: usize) -> Option<Self> {
-                uint_to!($t, n)
-            }
-            #[inline]
             fn from_u8(n: u8) -> Option<Self> {
                 uint_to!($t, n)
             }
@@ -101,10 +91,6 @@ macro_rules! impl_from_primitive_for_int {
 macro_rules! impl_from_primitive_for_uint {
     ($t:ident) => {
         impl FromPrimitive for $t {
-            #[inline]
-            fn from_isize(n: isize) -> Option<Self> {
-                int_to_uint!($t, n)
-            }
             #[inline]
             fn from_i8(n: i8) -> Option<Self> {
                 int_to_uint!($t, n)
@@ -122,10 +108,6 @@ macro_rules! impl_from_primitive_for_uint {
                 int_to_uint!($t, n)
             }
             #[inline]
-            fn from_usize(n: usize) -> Option<Self> {
-                uint_to!($t, n)
-            }
-            #[inline]
             fn from_u8(n: u8) -> Option<Self> {
                 uint_to!($t, n)
             }
@@ -148,10 +130,6 @@ macro_rules! impl_from_primitive_for_uint {
 macro_rules! impl_from_primitive_for_float {
     ($t:ident) => {
         impl FromPrimitive for $t {
-            #[inline]
-            fn from_isize(n: isize) -> Option<Self> {
-                Some(n as Self)
-            }
             #[inline]
             fn from_i8(n: i8) -> Option<Self> {
                 Some(n as Self)
@@ -169,10 +147,6 @@ macro_rules! impl_from_primitive_for_float {
                 Some(n as Self)
             }
             #[inline]
-            fn from_usize(n: usize) -> Option<Self> {
-                Some(n as Self)
-            }
-            #[inline]
             fn from_u8(n: u8) -> Option<Self> {
                 Some(n as Self)
             }
@@ -204,3 +178,91 @@ impl_from_primitive_for_uint!(u32);
 impl_from_primitive_for_uint!(u64);
 impl_from_primitive_for_float!(f32);
 impl_from_primitive_for_float!(f64);
+
+serde_if_integer128! {
+    impl FromPrimitive for i128 {
+        #[inline]
+        fn from_i8(n: i8) -> Option<Self> {
+            Some(n as i128)
+        }
+        #[inline]
+        fn from_i16(n: i16) -> Option<Self> {
+            Some(n as i128)
+        }
+        #[inline]
+        fn from_i32(n: i32) -> Option<Self> {
+            Some(n as i128)
+        }
+        #[inline]
+        fn from_i64(n: i64) -> Option<Self> {
+            Some(n as i128)
+        }
+        #[inline]
+        fn from_u8(n: u8) -> Option<Self> {
+            Some(n as i128)
+        }
+        #[inline]
+        fn from_u16(n: u16) -> Option<Self> {
+            Some(n as i128)
+        }
+        #[inline]
+        fn from_u32(n: u32) -> Option<Self> {
+            Some(n as i128)
+        }
+        #[inline]
+        fn from_u64(n: u64) -> Option<Self> {
+            Some(n as i128)
+        }
+    }
+
+    impl FromPrimitive for u128 {
+        #[inline]
+        fn from_i8(n: i8) -> Option<Self> {
+            if n >= 0 {
+                Some(n as u128)
+            } else {
+                None
+            }
+        }
+        #[inline]
+        fn from_i16(n: i16) -> Option<Self> {
+            if n >= 0 {
+                Some(n as u128)
+            } else {
+                None
+            }
+        }
+        #[inline]
+        fn from_i32(n: i32) -> Option<Self> {
+            if n >= 0 {
+                Some(n as u128)
+            } else {
+                None
+            }
+        }
+        #[inline]
+        fn from_i64(n: i64) -> Option<Self> {
+            if n >= 0 {
+                Some(n as u128)
+            } else {
+                None
+            }
+        }
+        #[inline]
+        fn from_u8(n: u8) -> Option<Self> {
+            Some(n as u128)
+        }
+        #[inline]
+        fn from_u16(n: u16) -> Option<Self> {
+            Some(n as u128)
+        }
+        #[inline]
+        fn from_u32(n: u32) -> Option<Self> {
+            Some(n as u128)
+        }
+        #[inline]
+        fn from_u64(n: u64) -> Option<Self> {
+            Some(n as u128)
+        }
+    }
+}

serde/src/de/ignored_any.rs

@@ -45,7 +45,8 @@ use de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
 /// }
 ///
 /// impl<'de, T> Visitor<'de> for NthElement<T>
-///     where T: Deserialize<'de>
+/// where
+///     T: Deserialize<'de>,
 /// {
 ///     type Value = T;
 ///
@@ -54,7 +55,8 @@ use de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
 ///     }
 ///
 ///     fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
-///         where A: SeqAccess<'de>
+///     where
+///         A: SeqAccess<'de>,
 ///     {
 ///         // Skip over the first `n` elements.
 ///         for i in 0..self.n {
@@ -82,19 +84,22 @@ use de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
 /// }
 ///
 /// impl<'de, T> DeserializeSeed<'de> for NthElement<T>
-///     where T: Deserialize<'de>
+/// where
+///     T: Deserialize<'de>,
 /// {
 ///     type Value = T;
 ///
 ///     fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
-///         where D: Deserializer<'de>
+///     where
+///         D: Deserializer<'de>,
 ///     {
 ///         deserializer.deserialize_seq(self)
 ///     }
 /// }
 ///
 /// # fn example<'de, D>(deserializer: D) -> Result<(), D::Error>
-/// #     where D: Deserializer<'de>
+/// # where
+/// #     D: Deserializer<'de>,
 /// # {
 /// // Deserialize only the sequence element at index 3 from this deserializer.
 /// // The element at index 3 is required to be a string. Elements before and

serde/src/de/impls.rs

@@ -8,10 +8,11 @@
 
 use lib::*;
 
-use de::{Deserialize, Deserializer, EnumAccess, Error, SeqAccess, Unexpected, VariantAccess,
-         Visitor};
+use de::{
+    Deserialize, Deserializer, EnumAccess, Error, SeqAccess, Unexpected, VariantAccess, Visitor,
+};
 
-#[cfg(any(feature = "std", feature = "alloc"))]
+#[cfg(any(core_duration, feature = "std", feature = "alloc"))]
 use de::MapAccess;
 
 use de::from_primitive::FromPrimitive;
@@ -31,7 +32,7 @@ impl<'de> Visitor<'de> for UnitVisitor {
         formatter.write_str("unit")
     }
 
-    fn visit_unit<E>(self) -> Result<(), E>
+    fn visit_unit<E>(self) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -40,7 +41,7 @@ impl<'de> Visitor<'de> for UnitVisitor {
 }
 
 impl<'de> Deserialize<'de> for () {
-    fn deserialize<D>(deserializer: D) -> Result<(), D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -48,6 +49,16 @@ impl<'de> Deserialize<'de> for () {
     }
 }
 
+#[cfg(feature = "unstable")]
+impl<'de> Deserialize<'de> for ! {
+    fn deserialize<D>(_deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        Err(Error::custom("cannot deserialize `!`"))
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 struct BoolVisitor;
@@ -59,7 +70,7 @@ impl<'de> Visitor<'de> for BoolVisitor {
         formatter.write_str("a boolean")
     }
 
-    fn visit_bool<E>(self, v: bool) -> Result<bool, E>
+    fn visit_bool<E>(self, v: bool) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -68,7 +79,7 @@ impl<'de> Visitor<'de> for BoolVisitor {
 }
 
 impl<'de> Deserialize<'de> for bool {
-    fn deserialize<D>(deserializer: D) -> Result<bool, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -109,7 +120,7 @@ macro_rules! impl_deserialize_num {
     ($ty:ident, $method:ident, $($visit:ident),*) => {
         impl<'de> Deserialize<'de> for $ty {
             #[inline]
-            fn deserialize<D>(deserializer: D) -> Result<$ty, D::Error>
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
                 D: Deserializer<'de>,
             {
@@ -165,6 +176,92 @@ impl_deserialize_num!(usize, deserialize_u64, integer);
 impl_deserialize_num!(f32, deserialize_f32, integer, float);
 impl_deserialize_num!(f64, deserialize_f64, integer, float);
 
+serde_if_integer128! {
+    impl<'de> Deserialize<'de> for i128 {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct PrimitiveVisitor;
+
+            impl<'de> Visitor<'de> for PrimitiveVisitor {
+                type Value = i128;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                    formatter.write_str("i128")
+                }
+
+                impl_deserialize_num!(integer i128);
+
+                #[inline]
+                fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    Ok(v)
+                }
+
+                #[inline]
+                fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    if v <= i128::max_value() as u128 {
+                        Ok(v as i128)
+                    } else {
+                        Err(Error::invalid_value(Unexpected::Other("u128"), &self))
+                    }
+                }
+            }
+
+            deserializer.deserialize_i128(PrimitiveVisitor)
+        }
+    }
+
+    impl<'de> Deserialize<'de> for u128 {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct PrimitiveVisitor;
+
+            impl<'de> Visitor<'de> for PrimitiveVisitor {
+                type Value = u128;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                    formatter.write_str("u128")
+                }
+
+                impl_deserialize_num!(integer u128);
+
+                #[inline]
+                fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    if v >= 0 {
+                        Ok(v as u128)
+                    } else {
+                        Err(Error::invalid_value(Unexpected::Other("i128"), &self))
+                    }
+                }
+
+                #[inline]
+                fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    Ok(v)
+                }
+            }
+
+            deserializer.deserialize_u128(PrimitiveVisitor)
+        }
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 struct CharVisitor;
@@ -177,7 +274,7 @@ impl<'de> Visitor<'de> for CharVisitor {
     }
 
     #[inline]
-    fn visit_char<E>(self, v: char) -> Result<char, E>
+    fn visit_char<E>(self, v: char) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -185,7 +282,7 @@ impl<'de> Visitor<'de> for CharVisitor {
     }
 
     #[inline]
-    fn visit_str<E>(self, v: &str) -> Result<char, E>
+    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -199,7 +296,7 @@ impl<'de> Visitor<'de> for CharVisitor {
 
 impl<'de> Deserialize<'de> for char {
     #[inline]
-    fn deserialize<D>(deserializer: D) -> Result<char, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -222,21 +319,21 @@ impl<'de> Visitor<'de> for StringVisitor {
         formatter.write_str("a string")
     }
 
-    fn visit_str<E>(self, v: &str) -> Result<String, E>
+    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
     where
         E: Error,
     {
         Ok(v.to_owned())
     }
 
-    fn visit_string<E>(self, v: String) -> Result<String, E>
+    fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
     where
         E: Error,
     {
         Ok(v)
     }
 
-    fn visit_bytes<E>(self, v: &[u8]) -> Result<String, E>
+    fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -246,7 +343,7 @@ impl<'de> Visitor<'de> for StringVisitor {
         }
     }
 
-    fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<String, E>
+    fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -268,7 +365,7 @@ impl<'a, 'de> Visitor<'de> for StringInPlaceVisitor<'a> {
         formatter.write_str("a string")
     }
 
-    fn visit_str<E>(self, v: &str) -> Result<(), E>
+    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -277,7 +374,7 @@ impl<'a, 'de> Visitor<'de> for StringInPlaceVisitor<'a> {
         Ok(())
     }
 
-    fn visit_string<E>(self, v: String) -> Result<(), E>
+    fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -285,7 +382,7 @@ impl<'a, 'de> Visitor<'de> for StringInPlaceVisitor<'a> {
         Ok(())
     }
 
-    fn visit_bytes<E>(self, v: &[u8]) -> Result<(), E>
+    fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -299,7 +396,7 @@ impl<'a, 'de> Visitor<'de> for StringInPlaceVisitor<'a> {
         }
     }
 
-    fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<(), E>
+    fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -318,7 +415,7 @@ impl<'a, 'de> Visitor<'de> for StringInPlaceVisitor<'a> {
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'de> Deserialize<'de> for String {
-    fn deserialize<D>(deserializer: D) -> Result<String, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -416,7 +513,7 @@ impl<'de> Visitor<'de> for CStringVisitor {
         formatter.write_str("byte array")
     }
 
-    fn visit_seq<A>(self, mut seq: A) -> Result<CString, A::Error>
+    fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
     where
         A: SeqAccess<'de>,
     {
@@ -430,28 +527,28 @@ impl<'de> Visitor<'de> for CStringVisitor {
         CString::new(values).map_err(Error::custom)
     }
 
-    fn visit_bytes<E>(self, v: &[u8]) -> Result<CString, E>
+    fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
     where
         E: Error,
     {
         CString::new(v).map_err(Error::custom)
     }
 
-    fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<CString, E>
+    fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
     where
         E: Error,
     {
         CString::new(v).map_err(Error::custom)
     }
 
-    fn visit_str<E>(self, v: &str) -> Result<CString, E>
+    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
     where
         E: Error,
     {
         CString::new(v).map_err(Error::custom)
     }
 
-    fn visit_string<E>(self, v: String) -> Result<CString, E>
+    fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -461,7 +558,7 @@ impl<'de> Visitor<'de> for CStringVisitor {
 
 #[cfg(feature = "std")]
 impl<'de> Deserialize<'de> for CString {
-    fn deserialize<D>(deserializer: D) -> Result<CString, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -486,7 +583,7 @@ macro_rules! forwarded_impl {
     }
 }
 
-#[cfg(all(feature = "std", feature = "unstable"))]
+#[cfg(all(feature = "std", de_boxed_c_str))]
 forwarded_impl!((), Box<CStr>, CString::into_boxed_c_str);
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -506,7 +603,7 @@ where
     }
 
     #[inline]
-    fn visit_unit<E>(self) -> Result<Option<T>, E>
+    fn visit_unit<E>(self) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -514,7 +611,7 @@ where
     }
 
     #[inline]
-    fn visit_none<E>(self) -> Result<Option<T>, E>
+    fn visit_none<E>(self) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -522,19 +619,27 @@ where
     }
 
     #[inline]
-    fn visit_some<D>(self, deserializer: D) -> Result<Option<T>, D::Error>
+    fn visit_some<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
     where
         D: Deserializer<'de>,
     {
         T::deserialize(deserializer).map(Some)
     }
+
+    #[doc(hidden)]
+    fn __private_visit_untagged_option<D>(self, deserializer: D) -> Result<Self::Value, ()>
+    where
+        D: Deserializer<'de>,
+    {
+        Ok(T::deserialize(deserializer).ok())
+    }
 }
 
 impl<'de, T> Deserialize<'de> for Option<T>
 where
     T: Deserialize<'de>,
 {
-    fn deserialize<D>(deserializer: D) -> Result<Option<T>, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -564,7 +669,7 @@ impl<'de, T: ?Sized> Visitor<'de> for PhantomDataVisitor<T> {
     }
 
     #[inline]
-    fn visit_unit<E>(self) -> Result<PhantomData<T>, E>
+    fn visit_unit<E>(self) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -573,7 +678,7 @@ impl<'de, T: ?Sized> Visitor<'de> for PhantomDataVisitor<T> {
 }
 
 impl<'de, T: ?Sized> Deserialize<'de> for PhantomData<T> {
-    fn deserialize<D>(deserializer: D) -> Result<PhantomData<T>, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -658,7 +763,7 @@ macro_rules! seq_impl {
                     }
 
                     #[inline]
-                    fn visit_seq<A>(mut self, mut $access: A) -> Result<(), A::Error>
+                    fn visit_seq<A>(mut self, mut $access: A) -> Result<Self::Value, A::Error>
                     where
                         A: SeqAccess<'de>,
                     {
@@ -770,7 +875,7 @@ impl<'de, T> Visitor<'de> for ArrayVisitor<[T; 0]> {
     }
 
     #[inline]
-    fn visit_seq<A>(self, _: A) -> Result<[T; 0], A::Error>
+    fn visit_seq<A>(self, _: A) -> Result<Self::Value, A::Error>
     where
         A: SeqAccess<'de>,
     {
@@ -780,7 +885,7 @@ impl<'de, T> Visitor<'de> for ArrayVisitor<[T; 0]> {
 
 // Does not require T: Deserialize<'de>.
 impl<'de, T> Deserialize<'de> for [T; 0] {
-    fn deserialize<D>(deserializer: D) -> Result<[T; 0], D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -802,7 +907,7 @@ macro_rules! array_impls {
                 }
 
                 #[inline]
-                fn visit_seq<A>(self, mut seq: A) -> Result<[T; $len], A::Error>
+                fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
                 where
                     A: SeqAccess<'de>,
                 {
@@ -828,7 +933,7 @@ macro_rules! array_impls {
                 }
 
                 #[inline]
-                fn visit_seq<A>(self, mut seq: A) -> Result<(), A::Error>
+                fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
                 where
                     A: SeqAccess<'de>,
                 {
@@ -850,7 +955,7 @@ macro_rules! array_impls {
             where
                 T: Deserialize<'de>,
             {
-                fn deserialize<D>(deserializer: D) -> Result<[T; $len], D::Error>
+                fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
                 where
                     D: Deserializer<'de>,
                 {
@@ -910,7 +1015,7 @@ macro_rules! tuple_impls {
         $(
             impl<'de, $($name: Deserialize<'de>),+> Deserialize<'de> for ($($name,)+) {
                 #[inline]
-                fn deserialize<D>(deserializer: D) -> Result<($($name,)+), D::Error>
+                fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
                 where
                     D: Deserializer<'de>,
                 {
@@ -927,7 +1032,7 @@ macro_rules! tuple_impls {
 
                         #[inline]
                         #[allow(non_snake_case)]
-                        fn visit_seq<A>(self, mut seq: A) -> Result<($($name,)+), A::Error>
+                        fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
                         where
                             A: SeqAccess<'de>,
                         {
@@ -961,7 +1066,7 @@ macro_rules! tuple_impls {
 
                         #[inline]
                         #[allow(non_snake_case)]
-                        fn visit_seq<A>(self, mut seq:                                                                      A) -> Result<(), A::Error>
+                        fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
                         where
                             A: SeqAccess<'de>,
                         {
@@ -1077,15 +1182,31 @@ map_impl!(
 
 #[cfg(feature = "std")]
 macro_rules! parse_ip_impl {
-    ($ty:ty; $size:expr) => {
+    ($expecting:tt $ty:ty; $size:tt) => {
         impl<'de> Deserialize<'de> for $ty {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
                 D: Deserializer<'de>,
             {
                 if deserializer.is_human_readable() {
-                    let s = try!(String::deserialize(deserializer));
-                    s.parse().map_err(Error::custom)
+                    struct IpAddrVisitor;
+
+                    impl<'de> Visitor<'de> for IpAddrVisitor {
+                        type Value = $ty;
+
+                        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                            formatter.write_str($expecting)
+                        }
+
+                        fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+                        where
+                            E: Error,
+                        {
+                            s.parse().map_err(Error::custom)
+                        }
+                    }
+
+                    deserializer.deserialize_str(IpAddrVisitor)
                 } else {
                     <[u8; $size]>::deserialize(deserializer).map(<$ty>::from)
                 }
@@ -1213,8 +1334,24 @@ impl<'de> Deserialize<'de> for net::IpAddr {
         D: Deserializer<'de>,
     {
         if deserializer.is_human_readable() {
-            let s = try!(String::deserialize(deserializer));
-            s.parse().map_err(Error::custom)
+            struct IpAddrVisitor;
+
+            impl<'de> Visitor<'de> for IpAddrVisitor {
+                type Value = net::IpAddr;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                    formatter.write_str("IP address")
+                }
+
+                fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    s.parse().map_err(Error::custom)
+                }
+            }
+
+            deserializer.deserialize_str(IpAddrVisitor)
         } else {
             use lib::net::IpAddr;
             deserialize_enum!{
@@ -1227,22 +1364,38 @@ impl<'de> Deserialize<'de> for net::IpAddr {
 }
 
 #[cfg(feature = "std")]
-parse_ip_impl!(net::Ipv4Addr; 4);
+parse_ip_impl!("IPv4 address" net::Ipv4Addr; 4);
 
 #[cfg(feature = "std")]
-parse_ip_impl!(net::Ipv6Addr; 16);
+parse_ip_impl!("IPv6 address" net::Ipv6Addr; 16);
 
 #[cfg(feature = "std")]
 macro_rules! parse_socket_impl {
-    ($ty:ty, $new:expr) => {
+    ($expecting:tt $ty:ty, $new:expr) => {
         impl<'de> Deserialize<'de> for $ty {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
                 D: Deserializer<'de>,
             {
                 if deserializer.is_human_readable() {
-                    let s = try!(String::deserialize(deserializer));
-                    s.parse().map_err(Error::custom)
+                    struct SocketAddrVisitor;
+
+                    impl<'de> Visitor<'de> for SocketAddrVisitor {
+                        type Value = $ty;
+
+                        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                            formatter.write_str($expecting)
+                        }
+
+                        fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+                        where
+                            E: Error,
+                        {
+                            s.parse().map_err(Error::custom)
+                        }
+                    }
+
+                    deserializer.deserialize_str(SocketAddrVisitor)
                 } else {
                     <(_, u16)>::deserialize(deserializer).map(|(ip, port)| $new(ip, port))
                 }
@@ -1258,8 +1411,24 @@ impl<'de> Deserialize<'de> for net::SocketAddr {
         D: Deserializer<'de>,
     {
         if deserializer.is_human_readable() {
-            let s = try!(String::deserialize(deserializer));
-            s.parse().map_err(Error::custom)
+            struct SocketAddrVisitor;
+
+            impl<'de> Visitor<'de> for SocketAddrVisitor {
+                type Value = net::SocketAddr;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                    formatter.write_str("socket address")
+                }
+
+                fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+                where
+                    E: Error,
+                {
+                    s.parse().map_err(Error::custom)
+                }
+            }
+
+            deserializer.deserialize_str(SocketAddrVisitor)
         } else {
             use lib::net::SocketAddr;
             deserialize_enum!{
@@ -1272,10 +1441,10 @@ impl<'de> Deserialize<'de> for net::SocketAddr {
 }
 
 #[cfg(feature = "std")]
-parse_socket_impl!(net::SocketAddrV4, net::SocketAddrV4::new);
+parse_socket_impl!("IPv4 socket address" net::SocketAddrV4, net::SocketAddrV4::new);
 
 #[cfg(feature = "std")]
-parse_socket_impl!(net::SocketAddrV6, |ip, port| net::SocketAddrV6::new(
+parse_socket_impl!("IPv6 socket address" net::SocketAddrV6, |ip, port| net::SocketAddrV6::new(
     ip, port, 0, 0
 ));
 
@@ -1330,14 +1499,14 @@ impl<'de> Visitor<'de> for PathBufVisitor {
         formatter.write_str("path string")
     }
 
-    fn visit_str<E>(self, v: &str) -> Result<PathBuf, E>
+    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
     where
         E: Error,
     {
         Ok(From::from(v))
     }
 
-    fn visit_string<E>(self, v: String) -> Result<PathBuf, E>
+    fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
     where
         E: Error,
     {
@@ -1347,7 +1516,7 @@ impl<'de> Visitor<'de> for PathBufVisitor {
 
 #[cfg(feature = "std")]
 impl<'de> Deserialize<'de> for PathBuf {
-    fn deserialize<D>(deserializer: D) -> Result<PathBuf, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -1380,7 +1549,7 @@ impl<'de> Visitor<'de> for OsStringVisitor {
     }
 
     #[cfg(unix)]
-    fn visit_enum<A>(self, data: A) -> Result<OsString, A::Error>
+    fn visit_enum<A>(self, data: A) -> Result<Self::Value, A::Error>
     where
         A: EnumAccess<'de>,
     {
@@ -1395,14 +1564,15 @@ impl<'de> Visitor<'de> for OsStringVisitor {
     }
 
     #[cfg(windows)]
-    fn visit_enum<A>(self, data: A) -> Result<OsString, A::Error>
+    fn visit_enum<A>(self, data: A) -> Result<Self::Value, A::Error>
     where
         A: EnumAccess<'de>,
     {
         use std::os::windows::ffi::OsStringExt;
 
         match try!(data.variant()) {
-            (OsStringKind::Windows, v) => v.newtype_variant::<Vec<u16>>()
+            (OsStringKind::Windows, v) => v
+                .newtype_variant::<Vec<u16>>()
                 .map(|vec| OsString::from_wide(&vec)),
             (OsStringKind::Unix, _) => Err(Error::custom(
                 "cannot deserialize Unix OS string on Windows",
@@ -1413,7 +1583,7 @@ impl<'de> Visitor<'de> for OsStringVisitor {
 
 #[cfg(all(feature = "std", any(unix, windows)))]
 impl<'de> Deserialize<'de> for OsString {
-    fn deserialize<D>(deserializer: D) -> Result<OsString, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -1432,7 +1602,7 @@ forwarded_impl!((T), Box<[T]>, Vec::into_boxed_slice);
 #[cfg(any(feature = "std", feature = "alloc"))]
 forwarded_impl!((), Box<str>, String::into_boxed_str);
 
-#[cfg(all(not(feature = "unstable"), feature = "rc", any(feature = "std", feature = "alloc")))]
+#[cfg(all(not(de_rc_dst), feature = "rc", any(feature = "std", feature = "alloc")))]
 forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1444,7 +1614,7 @@ forwarded_impl! {
     (T), Arc<T>, Arc::new
 }
 
-#[cfg(all(not(feature = "unstable"), feature = "rc", any(feature = "std", feature = "alloc")))]
+#[cfg(all(not(de_rc_dst), feature = "rc", any(feature = "std", feature = "alloc")))]
 forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1463,7 +1633,7 @@ where
     T::Owned: Deserialize<'de>,
 {
     #[inline]
-    fn deserialize<D>(deserializer: D) -> Result<Cow<'a, T>, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -1473,7 +1643,45 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(all(feature = "unstable", feature = "rc", any(feature = "std", feature = "alloc")))]
+/// This impl requires the [`"rc"`] Cargo feature of Serde. The resulting
+/// `Weak<T>` has a reference count of 0 and cannot be upgraded.
+///
+/// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
+impl<'de, T: ?Sized> Deserialize<'de> for RcWeak<T>
+where
+    T: Deserialize<'de>,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        try!(Option::<T>::deserialize(deserializer));
+        Ok(RcWeak::new())
+    }
+}
+
+/// This impl requires the [`"rc"`] Cargo feature of Serde. The resulting
+/// `Weak<T>` has a reference count of 0 and cannot be upgraded.
+///
+/// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
+impl<'de, T: ?Sized> Deserialize<'de> for ArcWeak<T>
+where
+    T: Deserialize<'de>,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        try!(Option::<T>::deserialize(deserializer));
+        Ok(ArcWeak::new())
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+#[cfg(all(de_rc_dst, feature = "rc", any(feature = "std", feature = "alloc")))]
 macro_rules! box_forwarded_impl {
     (
         $(#[doc = $doc:tt])*
@@ -1494,7 +1702,7 @@ macro_rules! box_forwarded_impl {
     };
 }
 
-#[cfg(all(feature = "unstable", feature = "rc", any(feature = "std", feature = "alloc")))]
+#[cfg(all(de_rc_dst, feature = "rc", any(feature = "std", feature = "alloc")))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1506,7 +1714,7 @@ box_forwarded_impl! {
     Rc
 }
 
-#[cfg(all(feature = "unstable", feature = "rc", any(feature = "std", feature = "alloc")))]
+#[cfg(all(de_rc_dst, feature = "rc", any(feature = "std", feature = "alloc")))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1524,7 +1732,7 @@ impl<'de, T> Deserialize<'de> for Cell<T>
 where
     T: Deserialize<'de> + Copy,
 {
-    fn deserialize<D>(deserializer: D) -> Result<Cell<T>, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -1550,7 +1758,7 @@ forwarded_impl!((T), RwLock<T>, RwLock::new);
 //         secs: u64,
 //         nanos: u32,
 //     }
-#[cfg(feature = "std")]
+#[cfg(any(core_duration, feature = "std"))]
 impl<'de> Deserialize<'de> for Duration {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -1566,7 +1774,7 @@ impl<'de> Deserialize<'de> for Duration {
         };
 
         impl<'de> Deserialize<'de> for Field {
-            fn deserialize<D>(deserializer: D) -> Result<Field, D::Error>
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
                 D: Deserializer<'de>,
             {
@@ -1579,7 +1787,7 @@ impl<'de> Deserialize<'de> for Duration {
                         formatter.write_str("`secs` or `nanos`")
                     }
 
-                    fn visit_str<E>(self, value: &str) -> Result<Field, E>
+                    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -1590,7 +1798,7 @@ impl<'de> Deserialize<'de> for Duration {
                         }
                     }
 
-                    fn visit_bytes<E>(self, value: &[u8]) -> Result<Field, E>
+                    fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -1598,7 +1806,7 @@ impl<'de> Deserialize<'de> for Duration {
                             b"secs" => Ok(Field::Secs),
                             b"nanos" => Ok(Field::Nanos),
                             _ => {
-                                let value = String::from_utf8_lossy(value);
+                                let value = ::export::from_utf8_lossy(value);
                                 Err(Error::unknown_field(&value, FIELDS))
                             }
                         }
@@ -1618,7 +1826,7 @@ impl<'de> Deserialize<'de> for Duration {
                 formatter.write_str("struct Duration")
             }
 
-            fn visit_seq<A>(self, mut seq: A) -> Result<Duration, A::Error>
+            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
             where
                 A: SeqAccess<'de>,
             {
@@ -1637,7 +1845,7 @@ impl<'de> Deserialize<'de> for Duration {
                 Ok(Duration::new(secs, nanos))
             }
 
-            fn visit_map<A>(self, mut map: A) -> Result<Duration, A::Error>
+            fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
             where
                 A: MapAccess<'de>,
             {
@@ -1691,7 +1899,7 @@ impl<'de> Deserialize<'de> for SystemTime {
         };
 
         impl<'de> Deserialize<'de> for Field {
-            fn deserialize<D>(deserializer: D) -> Result<Field, D::Error>
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
                 D: Deserializer<'de>,
             {
@@ -1704,7 +1912,7 @@ impl<'de> Deserialize<'de> for SystemTime {
                         formatter.write_str("`secs_since_epoch` or `nanos_since_epoch`")
                     }
 
-                    fn visit_str<E>(self, value: &str) -> Result<Field, E>
+                    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -1715,7 +1923,7 @@ impl<'de> Deserialize<'de> for SystemTime {
                         }
                     }
 
-                    fn visit_bytes<E>(self, value: &[u8]) -> Result<Field, E>
+                    fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -1743,7 +1951,7 @@ impl<'de> Deserialize<'de> for SystemTime {
                 formatter.write_str("struct SystemTime")
             }
 
-            fn visit_seq<A>(self, mut seq: A) -> Result<Duration, A::Error>
+            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
             where
                 A: SeqAccess<'de>,
             {
@@ -1762,7 +1970,7 @@ impl<'de> Deserialize<'de> for SystemTime {
                 Ok(Duration::new(secs, nanos))
             }
 
-            fn visit_map<A>(self, mut map: A) -> Result<Duration, A::Error>
+            fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
             where
                 A: MapAccess<'de>,
             {
@@ -1835,7 +2043,7 @@ where
         };
 
         impl<'de> Deserialize<'de> for Field {
-            fn deserialize<D>(deserializer: D) -> Result<Field, D::Error>
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
                 D: Deserializer<'de>,
             {
@@ -1848,7 +2056,7 @@ where
                         formatter.write_str("`start` or `end`")
                     }
 
-                    fn visit_str<E>(self, value: &str) -> Result<Field, E>
+                    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -1859,7 +2067,7 @@ where
                         }
                     }
 
-                    fn visit_bytes<E>(self, value: &[u8]) -> Result<Field, E>
+                    fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -1892,7 +2100,7 @@ where
                 formatter.write_str("struct Range")
             }
 
-            fn visit_seq<A>(self, mut seq: A) -> Result<ops::Range<Idx>, A::Error>
+            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
             where
                 A: SeqAccess<'de>,
             {
@@ -1911,7 +2119,7 @@ where
                 Ok(start..end)
             }
 
-            fn visit_map<A>(self, mut map: A) -> Result<ops::Range<Idx>, A::Error>
+            fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
             where
                 A: MapAccess<'de>,
             {
@@ -1958,35 +2166,17 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(feature = "unstable")]
-#[allow(deprecated)]
-impl<'de, T> Deserialize<'de> for NonZero<T>
-where
-    T: Deserialize<'de> + Zeroable,
-{
-    fn deserialize<D>(deserializer: D) -> Result<NonZero<T>, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        let value = try!(Deserialize::deserialize(deserializer));
-        match NonZero::new(value) {
-            Some(nonzero) => Ok(nonzero),
-            None => Err(Error::custom("expected a non-zero value")),
-        }
-    }
-}
-
 macro_rules! nonzero_integers {
-    ( $( $T: ty, )+ ) => {
+    ( $( $T: ident, )+ ) => {
         $(
-            #[cfg(feature = "unstable")]
-            impl<'de> Deserialize<'de> for $T {
-                fn deserialize<D>(deserializer: D) -> Result<$T, D::Error>
+            #[cfg(num_nonzero)]
+            impl<'de> Deserialize<'de> for num::$T {
+                fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
                 where
                     D: Deserializer<'de>,
                 {
                     let value = try!(Deserialize::deserialize(deserializer));
-                    match <$T>::new(value) {
+                    match <num::$T>::new(value) {
                         Some(nonzero) => Ok(nonzero),
                         None => Err(Error::custom("expected a non-zero value")),
                     }
@@ -2013,7 +2203,7 @@ where
     T: Deserialize<'de>,
     E: Deserialize<'de>,
 {
-    fn deserialize<D>(deserializer: D) -> Result<Result<T, E>, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
@@ -2028,7 +2218,7 @@ where
 
         impl<'de> Deserialize<'de> for Field {
             #[inline]
-            fn deserialize<D>(deserializer: D) -> Result<Field, D::Error>
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
                 D: Deserializer<'de>,
             {
@@ -2041,7 +2231,7 @@ where
                         formatter.write_str("`Ok` or `Err`")
                     }
 
-                    fn visit_u32<E>(self, value: u32) -> Result<Field, E>
+                    fn visit_u32<E>(self, value: u32) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -2055,7 +2245,7 @@ where
                         }
                     }
 
-                    fn visit_str<E>(self, value: &str) -> Result<Field, E>
+                    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -2066,7 +2256,7 @@ where
                         }
                     }
 
-                    fn visit_bytes<E>(self, value: &[u8]) -> Result<Field, E>
+                    fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
                     where
                         E: Error,
                     {
@@ -2100,7 +2290,7 @@ where
                 formatter.write_str("enum Result")
             }
 
-            fn visit_enum<A>(self, data: A) -> Result<Result<T, E>, A::Error>
+            fn visit_enum<A>(self, data: A) -> Result<Self::Value, A::Error>
             where
                 A: EnumAccess<'de>,
             {
@@ -2124,7 +2314,7 @@ impl<'de, T> Deserialize<'de> for Wrapping<T>
 where
     T: Deserialize<'de>,
 {
-    fn deserialize<D>(deserializer: D) -> Result<Wrapping<T>, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {

serde/src/de/mod.rs

@@ -52,12 +52,12 @@
 //!
 //!  - **Primitive types**:
 //!    - bool
-//!    - i8, i16, i32, i64, isize
-//!    - u8, u16, u32, u64, usize
+//!    - i8, i16, i32, i64, i128, isize
+//!    - u8, u16, u32, u64, u128, usize
 //!    - f32, f64
 //!    - char
 //!  - **Compound types**:
-//!    - [T; 0] through [T; 32]
+//!    - \[T; 0\] through \[T; 32\]
 //!    - tuples up to size 16
 //!  - **Common standard library types**:
 //!    - String
@@ -66,7 +66,7 @@
 //!    - PhantomData\<T\>
 //!  - **Wrapper types**:
 //!    - Box\<T\>
-//!    - Box\<[T]\>
+//!    - Box\<\[T\]\>
 //!    - Box\<str\>
 //!    - Rc\<T\>
 //!    - Arc\<T\>
@@ -84,10 +84,9 @@
 //!    - LinkedList\<T\>
 //!    - VecDeque\<T\>
 //!    - Vec\<T\>
-//!    - EnumSet\<T\> (unstable)
 //!  - **Zero-copy types**:
 //!    - &str
-//!    - &[u8]
+//!    - &\[u8\]
 //!  - **FFI types**:
 //!    - CString
 //!    - Box\<CStr\>
@@ -98,8 +97,8 @@
 //!    - Path
 //!    - PathBuf
 //!    - Range\<T\>
-//!    - NonZero\<T\> (unstable, deprecated)
-//!    - num::NonZero* (unstable)
+//!    - num::NonZero*
+//!    - `!` *(unstable)*
 //!  - **Net types**:
 //!    - IpAddr
 //!    - Ipv4Addr
@@ -150,6 +149,13 @@ macro_rules! declare_error_trait {
         ///
         /// Most deserializers should only need to provide the `Error::custom` method
         /// and inherit the default behavior for the other methods.
+        ///
+        /// # Example implementation
+        ///
+        /// The [example data format] presented on the website shows an error
+        /// type appropriate for a basic JSON data format.
+        ///
+        /// [example data format]: https://serde.rs/data-format.html
         pub trait Error: Sized $(+ $($supertrait)::+)* {
             /// Raised when there is general error when deserializing a type.
             ///
@@ -172,7 +178,8 @@ macro_rules! declare_error_trait {
             ///
             /// impl<'de> Deserialize<'de> for IpAddr {
             ///     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-            ///         where D: Deserializer<'de>
+            ///     where
+            ///         D: Deserializer<'de>,
             ///     {
             ///         let s = try!(String::deserialize(deserializer));
             ///         s.parse().map_err(de::Error::custom)
@@ -306,7 +313,8 @@ declare_error_trait!(Error: Sized + Debug + Display);
 /// #     }
 /// #
 /// fn visit_bool<E>(self, v: bool) -> Result<Self::Value, E>
-///     where E: de::Error
+/// where
+///     E: de::Error,
 /// {
 ///     Err(de::Error::invalid_type(Unexpected::Bool(v), &self))
 /// }
@@ -430,7 +438,8 @@ impl<'a> fmt::Display for Unexpected<'a> {
 /// #     }
 /// #
 /// fn visit_bool<E>(self, v: bool) -> Result<Self::Value, E>
-///     where E: de::Error
+/// where
+///     E: de::Error,
 /// {
 ///     Err(de::Error::invalid_type(Unexpected::Bool(v), &self))
 /// }
@@ -443,7 +452,8 @@ impl<'a> fmt::Display for Unexpected<'a> {
 /// # use serde::de::{self, Unexpected};
 /// #
 /// # fn example<E>() -> Result<(), E>
-/// #     where E: de::Error
+/// # where
+/// #     E: de::Error,
 /// # {
 /// #     let v = true;
 /// return Err(de::Error::invalid_type(Unexpected::Bool(v), &"a negative integer"));
@@ -502,6 +512,14 @@ impl<'a> Display for Expected + 'a {
 /// [de]: https://docs.serde.rs/serde/de/index.html
 /// [codegen]: https://serde.rs/codegen.html
 /// [impl-deserialize]: https://serde.rs/impl-deserialize.html
+///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the lifetime of data that may be
+/// borrowed by `Self` when deserialized. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
 pub trait Deserialize<'de>: Sized {
     /// Deserialize this value from the given Serde deserializer.
     ///
@@ -557,13 +575,23 @@ pub trait Deserialize<'de>: Sized {
 /// #
 /// # trait Ignore {
 /// fn from_str<'a, T>(s: &'a str) -> Result<T>
-///     where T: Deserialize<'a>;
+/// where
+///     T: Deserialize<'a>;
 ///
 /// fn from_reader<R, T>(rdr: R) -> Result<T>
-///     where R: Read,
-///           T: DeserializeOwned;
+/// where
+///     R: Read,
+///     T: DeserializeOwned;
 /// # }
 /// ```
+///
+/// # Lifetime
+///
+/// The relationship between `Deserialize` and `DeserializeOwned` in trait
+/// bounds is explained in more detail on the page [Understanding deserializer
+/// lifetimes].
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
 pub trait DeserializeOwned: for<'de> Deserialize<'de> {}
 impl<T> DeserializeOwned for T
 where
@@ -614,6 +642,14 @@ where
 /// seed can be appeased by passing `std::marker::PhantomData` as a seed in the
 /// case of stateless deserialization.
 ///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the lifetime of data that may be
+/// borrowed by `Self::Value` when deserialized. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+///
 /// # Example
 ///
 /// Suppose we have JSON that looks like `[[1, 2], [3, 4, 5], [6]]` and we need
@@ -637,7 +673,8 @@ where
 /// struct ExtendVec<'a, T: 'a>(&'a mut Vec<T>);
 ///
 /// impl<'de, 'a, T> DeserializeSeed<'de> for ExtendVec<'a, T>
-///     where T: Deserialize<'de>
+/// where
+///     T: Deserialize<'de>,
 /// {
 ///     // The return type of the `deserialize` method. This implementation
 ///     // appends onto an existing vector but does not create any new data
@@ -645,14 +682,16 @@ where
 ///     type Value = ();
 ///
 ///     fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
-///         where D: Deserializer<'de>
+///     where
+///         D: Deserializer<'de>,
 ///     {
 ///         // Visitor implementation that will walk an inner array of the JSON
 ///         // input.
 ///         struct ExtendVecVisitor<'a, T: 'a>(&'a mut Vec<T>);
 ///
 ///         impl<'de, 'a, T> Visitor<'de> for ExtendVecVisitor<'a, T>
-///             where T: Deserialize<'de>
+///         where
+///             T: Deserialize<'de>,
 ///         {
 ///             type Value = ();
 ///
@@ -661,7 +700,8 @@ where
 ///             }
 ///
 ///             fn visit_seq<A>(self, mut seq: A) -> Result<(), A::Error>
-///                 where A: SeqAccess<'de>
+///             where
+///                 A: SeqAccess<'de>,
 ///             {
 ///                 // Visit each element in the inner array and push it onto
 ///                 // the existing vector.
@@ -680,7 +720,8 @@ where
 /// struct FlattenedVecVisitor<T>(PhantomData<T>);
 ///
 /// impl<'de, T> Visitor<'de> for FlattenedVecVisitor<T>
-///     where T: Deserialize<'de>
+/// where
+///     T: Deserialize<'de>,
 /// {
 ///     // This Visitor constructs a single Vec<T> to hold the flattened
 ///     // contents of the inner arrays.
@@ -691,7 +732,8 @@ where
 ///     }
 ///
 ///     fn visit_seq<A>(self, mut seq: A) -> Result<Vec<T>, A::Error>
-///         where A: SeqAccess<'de>
+///     where
+///         A: SeqAccess<'de>,
 ///     {
 ///         // Create a single Vec to hold the flattened contents.
 ///         let mut vec = Vec::new();
@@ -707,7 +749,8 @@ where
 /// }
 ///
 /// # fn example<'de, D>(deserializer: D) -> Result<(), D::Error>
-/// #     where D: Deserializer<'de>
+/// # where
+/// #     D: Deserializer<'de>,
 /// # {
 /// let visitor = FlattenedVecVisitor(PhantomData);
 /// let flattened: Vec<u64> = deserializer.deserialize_seq(visitor)?;
@@ -745,10 +788,10 @@ where
 /// A **data format** that can deserialize any data structure supported by
 /// Serde.
 ///
-/// The role of this trait is to define the deserialization half of the Serde
-/// data model, which is a way to categorize every Rust data type into one of 27
-/// possible types. Each method of the `Serializer` trait corresponds to one of
-/// the types of the data model.
+/// The role of this trait is to define the deserialization half of the [Serde
+/// data model], which is a way to categorize every Rust data type into one of
+/// 29 possible types. Each method of the `Serializer` trait corresponds to one
+/// of the types of the data model.
 ///
 /// Implementations of `Deserialize` map themselves into this data model by
 /// passing to the `Deserializer` a `Visitor` implementation that can receive
@@ -756,17 +799,17 @@ where
 ///
 /// The types that make up the Serde data model are:
 ///
-///  - **12 primitive types**
+///  - **14 primitive types**
 ///    - bool
-///    - i8, i16, i32, i64
-///    - u8, u16, u32, u64
+///    - i8, i16, i32, i64, i128
+///    - u8, u16, u32, u64, u128
 ///    - f32, f64
 ///    - char
 ///  - **string**
 ///    - UTF-8 bytes with a length and no null terminator.
 ///    - When serializing, all strings are handled equally. When deserializing,
 ///      there are three flavors of strings: transient, owned, and borrowed.
-///  - **byte array** - [u8]
+///  - **byte array** - \[u8\]
 ///    - Similar to strings, during deserialization byte arrays can be transient,
 ///      owned, or borrowed.
 ///  - **option**
@@ -830,6 +873,23 @@ where
 /// what type is in the input. Know that relying on `Deserializer::deserialize_any`
 /// means your data type will be able to deserialize from self-describing
 /// formats only, ruling out Bincode and many others.
+///
+/// [Serde data model]: https://serde.rs/data-model.html
+///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the lifetime of data that may be
+/// borrowed from the input when deserializing. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website contains example code for
+/// a basic JSON `Deserializer`.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait Deserializer<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -873,6 +933,20 @@ pub trait Deserializer<'de>: Sized {
     where
         V: Visitor<'de>;
 
+    serde_if_integer128! {
+        /// Hint that the `Deserialize` type is expecting an `i128` value.
+        ///
+        /// This method is available only on Rust compiler versions >=1.26. The
+        /// default behavior unconditionally returns an error.
+        fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where
+            V: Visitor<'de>
+        {
+            let _ = visitor;
+            Err(Error::custom("i128 is not supported"))
+        }
+    }
+
     /// Hint that the `Deserialize` type is expecting a `u8` value.
     fn deserialize_u8<V>(self, visitor: V) -> Result<V::Value, Self::Error>
     where
@@ -893,6 +967,20 @@ pub trait Deserializer<'de>: Sized {
     where
         V: Visitor<'de>;
 
+    serde_if_integer128! {
+        /// Hint that the `Deserialize` type is expecting an `u128` value.
+        ///
+        /// This method is available only on Rust compiler versions >=1.26. The
+        /// default behavior unconditionally returns an error.
+        fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where
+            V: Visitor<'de>
+        {
+            let _ = visitor;
+            Err(Error::custom("u128 is not supported"))
+        }
+    }
+
     /// Hint that the `Deserialize` type is expecting a `f32` value.
     fn deserialize_f32<V>(self, visitor: V) -> Result<V::Value, Self::Error>
     where
@@ -1092,7 +1180,8 @@ pub trait Deserializer<'de>: Sized {
     ///
     /// impl<'de> Deserialize<'de> for Timestamp {
     ///     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    ///         where D: Deserializer<'de>
+    ///     where
+    ///         D: Deserializer<'de>,
     ///     {
     ///         if deserializer.is_human_readable() {
     ///             // Deserialize from a human-readable string like "2015-05-15T17:01:00Z".
@@ -1124,6 +1213,16 @@ pub trait Deserializer<'de>: Sized {
 
 /// This trait represents a visitor that walks through a deserializer.
 ///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the requirement for lifetime of data
+/// that may be borrowed by `Self::Value`. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+///
+/// # Example
+///
 /// ```rust
 /// # use std::fmt;
 /// #
@@ -1143,7 +1242,8 @@ pub trait Deserializer<'de>: Sized {
 ///     }
 ///
 ///     fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
-///         where E: de::Error
+///     where
+///         E: de::Error,
 ///     {
 ///         if s.len() >= self.min {
 ///             Ok(s.to_owned())
@@ -1237,6 +1337,20 @@ pub trait Visitor<'de>: Sized {
         Err(Error::invalid_type(Unexpected::Signed(v), &self))
     }
 
+    serde_if_integer128! {
+        /// The input contains a `i128`.
+        ///
+        /// This method is available only on Rust compiler versions >=1.26. The
+        /// default implementation fails with a type error.
+        fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E>
+        where
+            E: Error,
+        {
+            let _ = v;
+            Err(Error::invalid_type(Unexpected::Other("i128"), &self))
+        }
+    }
+
     /// The input contains a `u8`.
     ///
     /// The default implementation forwards to [`visit_u64`].
@@ -1283,6 +1397,20 @@ pub trait Visitor<'de>: Sized {
         Err(Error::invalid_type(Unexpected::Unsigned(v), &self))
     }
 
+    serde_if_integer128! {
+        /// The input contains a `u128`.
+        ///
+        /// This method is available only on Rust compiler versions >=1.26. The
+        /// default implementation fails with a type error.
+        fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E>
+        where
+            E: Error,
+        {
+            let _ = v;
+            Err(Error::invalid_type(Unexpected::Other("u128"), &self))
+        }
+    }
+
     /// The input contains an `f32`.
     ///
     /// The default implementation forwards to [`visit_f64`].
@@ -1514,6 +1642,15 @@ pub trait Visitor<'de>: Sized {
         let _ = data;
         Err(Error::invalid_type(Unexpected::Enum, &self))
     }
+
+    // Used when deserializing a flattened Option field. Not public API.
+    #[doc(hidden)]
+    fn __private_visit_untagged_option<D>(self, _: D) -> Result<Self::Value, ()>
+    where
+        D: Deserializer<'de>,
+    {
+        Err(())
+    }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -1522,6 +1659,21 @@ pub trait Visitor<'de>: Sized {
 ///
 /// This is a trait that a `Deserializer` passes to a `Visitor` implementation,
 /// which deserializes each item in a sequence.
+///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the lifetime of data that may be
+/// borrowed by deserialized sequence elements. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `SeqAccess` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait SeqAccess<'de> {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1589,6 +1741,21 @@ where
 /// Provides a `Visitor` access to each entry of a map in the input.
 ///
 /// This is a trait that a `Deserializer` passes to a `Visitor` implementation.
+///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the lifetime of data that may be
+/// borrowed by deserialized map entries. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `MapAccess` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait MapAccess<'de> {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1766,6 +1933,21 @@ where
 ///
 /// `EnumAccess` is created by the `Deserializer` and passed to the
 /// `Visitor` in order to identify which variant of an enum to deserialize.
+///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the lifetime of data that may be
+/// borrowed by the deserialized enum variant. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `EnumAccess` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait EnumAccess<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1798,6 +1980,21 @@ pub trait EnumAccess<'de>: Sized {
 /// `VariantAccess` is a visitor that is created by the `Deserializer` and
 /// passed to the `Deserialize` to deserialize the content of a particular enum
 /// variant.
+///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the lifetime of data that may be
+/// borrowed by the deserialized enum variant. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `VariantAccess` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait VariantAccess<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization. Must match the error type of our `EnumAccess`.
@@ -1823,15 +2020,18 @@ pub trait VariantAccess<'de>: Sized {
     /// }
     /// #
     /// #     fn newtype_variant_seed<T>(self, _: T) -> Result<T::Value, Self::Error>
-    /// #         where T: DeserializeSeed<'de>
+    /// #     where
+    /// #         T: DeserializeSeed<'de>,
     /// #     { unimplemented!() }
     /// #
     /// #     fn tuple_variant<V>(self, _: usize, _: V) -> Result<V::Value, Self::Error>
-    /// #         where V: Visitor<'de>
+    /// #     where
+    /// #         V: Visitor<'de>,
     /// #     { unimplemented!() }
     /// #
     /// #     fn struct_variant<V>(self, _: &[&str], _: V) -> Result<V::Value, Self::Error>
-    /// #         where V: Visitor<'de>
+    /// #     where
+    /// #         V: Visitor<'de>,
     /// #     { unimplemented!() }
     /// # }
     /// ```
@@ -1858,7 +2058,8 @@ pub trait VariantAccess<'de>: Sized {
     /// #     }
     /// #
     /// fn newtype_variant_seed<T>(self, _seed: T) -> Result<T::Value, Self::Error>
-    ///     where T: DeserializeSeed<'de>
+    /// where
+    ///     T: DeserializeSeed<'de>,
     /// {
     ///     // What the data actually contained; suppose it is a unit variant.
     ///     let unexp = Unexpected::UnitVariant;
@@ -1866,11 +2067,13 @@ pub trait VariantAccess<'de>: Sized {
     /// }
     /// #
     /// #     fn tuple_variant<V>(self, _: usize, _: V) -> Result<V::Value, Self::Error>
-    /// #         where V: Visitor<'de>
+    /// #     where
+    /// #         V: Visitor<'de>,
     /// #     { unimplemented!() }
     /// #
     /// #     fn struct_variant<V>(self, _: &[&str], _: V) -> Result<V::Value, Self::Error>
-    /// #         where V: Visitor<'de>
+    /// #     where
+    /// #         V: Visitor<'de>,
     /// #     { unimplemented!() }
     /// # }
     /// ```
@@ -1911,13 +2114,17 @@ pub trait VariantAccess<'de>: Sized {
     /// #     }
     /// #
     /// #     fn newtype_variant_seed<T>(self, _: T) -> Result<T::Value, Self::Error>
-    /// #         where T: DeserializeSeed<'de>
+    /// #     where
+    /// #         T: DeserializeSeed<'de>,
     /// #     { unimplemented!() }
     /// #
-    /// fn tuple_variant<V>(self,
-    ///                         _len: usize,
-    ///                         _visitor: V) -> Result<V::Value, Self::Error>
-    ///     where V: Visitor<'de>
+    /// fn tuple_variant<V>(
+    ///     self,
+    ///     _len: usize,
+    ///     _visitor: V,
+    /// ) -> Result<V::Value, Self::Error>
+    /// where
+    ///     V: Visitor<'de>,
     /// {
     ///     // What the data actually contained; suppose it is a unit variant.
     ///     let unexp = Unexpected::UnitVariant;
@@ -1925,7 +2132,8 @@ pub trait VariantAccess<'de>: Sized {
     /// }
     /// #
     /// #     fn struct_variant<V>(self, _: &[&str], _: V) -> Result<V::Value, Self::Error>
-    /// #         where V: Visitor<'de>
+    /// #     where
+    /// #         V: Visitor<'de>,
     /// #     { unimplemented!() }
     /// # }
     /// ```
@@ -1953,17 +2161,22 @@ pub trait VariantAccess<'de>: Sized {
     /// #     }
     /// #
     /// #     fn newtype_variant_seed<T>(self, _: T) -> Result<T::Value, Self::Error>
-    /// #         where T: DeserializeSeed<'de>
+    /// #     where
+    /// #         T: DeserializeSeed<'de>,
     /// #     { unimplemented!() }
     /// #
     /// #     fn tuple_variant<V>(self, _: usize, _: V) -> Result<V::Value, Self::Error>
-    /// #         where V: Visitor<'de>
+    /// #     where
+    /// #         V: Visitor<'de>,
     /// #     { unimplemented!() }
     /// #
-    /// fn struct_variant<V>(self,
-    ///                          _fields: &'static [&'static str],
-    ///                          _visitor: V) -> Result<V::Value, Self::Error>
-    ///     where V: Visitor<'de>
+    /// fn struct_variant<V>(
+    ///     self,
+    ///     _fields: &'static [&'static str],
+    ///     _visitor: V,
+    /// ) -> Result<V::Value, Self::Error>
+    /// where
+    ///     V: Visitor<'de>,
     /// {
     ///     // What the data actually contained; suppose it is a unit variant.
     ///     let unexp = Unexpected::UnitVariant;
@@ -1985,6 +2198,16 @@ pub trait VariantAccess<'de>: Sized {
 /// Converts an existing value into a `Deserializer` from which other values can
 /// be deserialized.
 ///
+/// # Lifetime
+///
+/// The `'de` lifetime of this trait is the lifetime of data that may be
+/// borrowed from the resulting `Deserializer`. See the page [Understanding
+/// deserializer lifetimes] for a more detailed explanation of these lifetimes.
+///
+/// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+///
+/// # Example
+///
 /// ```rust
 /// #[macro_use]
 /// extern crate serde_derive;

serde/src/de/value.rs

@@ -44,6 +44,22 @@ use ser;
 
 ////////////////////////////////////////////////////////////////////////////////
 
+// For structs that contain a PhantomData. We do not want the trait
+// bound `E: Clone` inferred by derive(Clone).
+macro_rules! impl_copy_clone {
+    ($ty:ident $(<$lifetime:tt>)*) => {
+        impl<$($lifetime,)* E> Copy for $ty<$($lifetime,)* E> {}
+
+        impl<$($lifetime,)* E> Clone for $ty<$($lifetime,)* E> {
+            fn clone(&self) -> Self {
+                *self
+            }
+        }
+    };
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 /// A minimal representation of all possible errors that can occur using the
 /// `IntoDeserializer` trait.
 #[derive(Clone, Debug, PartialEq)]
@@ -124,11 +140,13 @@ where
 }
 
 /// A deserializer holding a `()`.
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct UnitDeserializer<E> {
     marker: PhantomData<E>,
 }
 
+impl_copy_clone!(UnitDeserializer);
+
 impl<'de, E> de::Deserializer<'de> for UnitDeserializer<E>
 where
     E: de::Error,
@@ -136,9 +154,9 @@ where
     type Error = E;
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf unit unit_struct newtype_struct seq tuple tuple_struct map
-        struct enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf unit unit_struct newtype_struct seq tuple tuple_struct
+        map struct enum identifier ignored_any
     }
 
     fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -158,16 +176,60 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
+/// A deserializer that cannot be instantiated.
+#[cfg(feature = "unstable")]
+pub struct NeverDeserializer<E> {
+    never: !,
+    marker: PhantomData<E>,
+}
+
+#[cfg(feature = "unstable")]
+impl<'de, E> IntoDeserializer<'de, E> for !
+where
+    E: de::Error,
+{
+    type Deserializer = NeverDeserializer<E>;
+
+    fn into_deserializer(self) -> Self::Deserializer {
+        self
+    }
+}
+
+#[cfg(feature = "unstable")]
+impl<'de, E> de::Deserializer<'de> for NeverDeserializer<E>
+where
+    E: de::Error,
+{
+    type Error = E;
+
+    fn deserialize_any<V>(self, _visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: de::Visitor<'de>,
+    {
+        self.never
+    }
+
+    forward_to_deserialize_any! {
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct enum identifier ignored_any
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 macro_rules! primitive_deserializer {
     ($ty:ty, $doc:tt, $name:ident, $method:ident $($cast:tt)*) => {
         #[doc = "A deserializer holding"]
         #[doc = $doc]
-        #[derive(Clone, Debug)]
+        #[derive(Debug)]
         pub struct $name<E> {
             value: $ty,
             marker: PhantomData<E>
         }
 
+        impl_copy_clone!($name);
+
         impl<'de, E> IntoDeserializer<'de, E> for $ty
         where
             E: de::Error,
@@ -189,9 +251,9 @@ macro_rules! primitive_deserializer {
             type Error = E;
 
             forward_to_deserialize_any! {
-                bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-                byte_buf option unit unit_struct newtype_struct seq tuple
-                tuple_struct map struct enum identifier ignored_any
+                bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str
+                string bytes byte_buf option unit unit_struct newtype_struct seq
+                tuple tuple_struct map struct enum identifier ignored_any
             }
 
             fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -218,13 +280,20 @@ primitive_deserializer!(f32, "an `f32`.", F32Deserializer, visit_f32);
 primitive_deserializer!(f64, "an `f64`.", F64Deserializer, visit_f64);
 primitive_deserializer!(char, "a `char`.", CharDeserializer, visit_char);
 
+serde_if_integer128! {
+    primitive_deserializer!(i128, "an `i128`.", I128Deserializer, visit_i128);
+    primitive_deserializer!(u128, "a `u128`.", U128Deserializer, visit_u128);
+}
+
 /// A deserializer holding a `u32`.
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct U32Deserializer<E> {
     value: u32,
     marker: PhantomData<E>,
 }
 
+impl_copy_clone!(U32Deserializer);
+
 impl<'de, E> IntoDeserializer<'de, E> for u32
 where
     E: de::Error,
@@ -246,9 +315,9 @@ where
     type Error = E;
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct identifier ignored_any
     }
 
     fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -291,12 +360,14 @@ where
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `&str`.
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct StrDeserializer<'a, E> {
     value: &'a str,
     marker: PhantomData<E>,
 }
 
+impl_copy_clone!(StrDeserializer<'de>);
+
 impl<'de, 'a, E> IntoDeserializer<'de, E> for &'a str
 where
     E: de::Error,
@@ -339,9 +410,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct identifier ignored_any
     }
 }
 
@@ -364,12 +435,14 @@ where
 
 /// A deserializer holding a `&str` with a lifetime tied to another
 /// deserializer.
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct BorrowedStrDeserializer<'de, E> {
     value: &'de str,
     marker: PhantomData<E>,
 }
 
+impl_copy_clone!(BorrowedStrDeserializer<'de>);
+
 impl<'de, E> BorrowedStrDeserializer<'de, E> {
     /// Create a new borrowed deserializer from the given string.
     pub fn new(value: &'de str) -> BorrowedStrDeserializer<'de, E> {
@@ -408,9 +481,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct identifier ignored_any
     }
 }
 
@@ -433,12 +506,22 @@ where
 
 /// A deserializer holding a `String`.
 #[cfg(any(feature = "std", feature = "alloc"))]
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct StringDeserializer<E> {
     value: String,
     marker: PhantomData<E>,
 }
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<E> Clone for StringDeserializer<E> {
+    fn clone(&self) -> Self {
+        StringDeserializer {
+            value: self.value.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'de, E> IntoDeserializer<'de, E> for String
 where
@@ -483,9 +566,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct identifier ignored_any
     }
 }
 
@@ -509,12 +592,22 @@ where
 
 /// A deserializer holding a `Cow<str>`.
 #[cfg(any(feature = "std", feature = "alloc"))]
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct CowStrDeserializer<'a, E> {
     value: Cow<'a, str>,
     marker: PhantomData<E>,
 }
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, E> Clone for CowStrDeserializer<'a, E> {
+    fn clone(&self) -> Self {
+        CowStrDeserializer {
+            value: self.value.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'de, 'a, E> IntoDeserializer<'de, E> for Cow<'a, str>
 where
@@ -562,9 +655,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct identifier ignored_any
     }
 }
 
@@ -588,12 +681,14 @@ where
 
 /// A deserializer holding a `&[u8]` with a lifetime tied to another
 /// deserializer.
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct BorrowedBytesDeserializer<'de, E> {
     value: &'de [u8],
     marker: PhantomData<E>,
 }
 
+impl_copy_clone!(BorrowedBytesDeserializer<'de>);
+
 impl<'de, E> BorrowedBytesDeserializer<'de, E> {
     /// Create a new borrowed deserializer from the given byte slice.
     pub fn new(value: &'de [u8]) -> BorrowedBytesDeserializer<'de, E> {
@@ -618,9 +713,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct identifier ignored_any enum
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct identifier ignored_any enum
     }
 }
 
@@ -688,9 +783,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct enum identifier ignored_any
     }
 }
 
@@ -803,9 +898,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct enum identifier ignored_any
     }
 }
 
@@ -917,9 +1012,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct tuple_struct map struct
-        enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct tuple_struct map
+        struct enum identifier ignored_any
     }
 }
 
@@ -1059,9 +1154,9 @@ where
     type Error = E;
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct tuple_struct map struct
-        enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct tuple_struct map
+        struct enum identifier ignored_any
     }
 
     fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -1207,9 +1302,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct enum identifier ignored_any
     }
 }
 

serde/src/integer128.rs

@@ -0,0 +1,86 @@
+/// Conditional compilation depending on whether Serde is built with support for
+/// 128-bit integers.
+///
+/// Data formats that wish to support Rust compiler versions older than 1.26 may
+/// place the i128 / u128 methods of their Serializer and Deserializer behind
+/// this macro.
+///
+/// Data formats that require a minimum Rust compiler version of at least 1.26
+/// do not need to bother with this macro and may assume support for 128-bit
+/// integers.
+///
+/// ```rust
+/// #[macro_use]
+/// extern crate serde;
+///
+/// use serde::Serializer;
+/// # use serde::private::ser::Error;
+/// #
+/// # struct MySerializer;
+///
+/// impl Serializer for MySerializer {
+///     type Ok = ();
+///     type Error = Error;
+///
+///     fn serialize_i64(self, v: i64) -> Result<Self::Ok, Self::Error> {
+///         /* ... */
+/// #         unimplemented!()
+///     }
+///
+///     /* ... */
+///
+///     serde_if_integer128! {
+///         fn serialize_i128(self, v: i128) -> Result<Self::Ok, Self::Error> {
+///             /* ... */
+/// #             unimplemented!()
+///         }
+///
+///         fn serialize_u128(self, v: u128) -> Result<Self::Ok, Self::Error> {
+///             /* ... */
+/// #             unimplemented!()
+///         }
+///     }
+/// #
+/// #     __serialize_unimplemented! {
+/// #         bool i8 i16 i32 u8 u16 u32 u64 f32 f64 char str bytes none some
+/// #         unit unit_struct unit_variant newtype_struct newtype_variant seq
+/// #         tuple tuple_struct tuple_variant map struct struct_variant
+/// #     }
+/// }
+/// #
+/// # fn main() {}
+/// ```
+///
+/// When Serde is built with support for 128-bit integers, this macro expands
+/// transparently into just the input tokens.
+///
+/// ```rust
+/// macro_rules! serde_if_integer128 {
+///     ($($tt:tt)*) => {
+///         $($tt)*
+///     };
+/// }
+/// ```
+///
+/// When built without support for 128-bit integers, this macro expands to
+/// nothing.
+///
+/// ```rust
+/// macro_rules! serde_if_integer128 {
+///     ($($tt:tt)*) => {};
+/// }
+/// ```
+#[cfg(integer128)]
+#[macro_export]
+macro_rules! serde_if_integer128 {
+    ($($tt:tt)*) => {
+        $($tt)*
+    };
+}
+
+#[cfg(not(integer128))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! serde_if_integer128 {
+    ($($tt:tt)*) => {};
+}

serde/src/lib.rs

@@ -52,6 +52,8 @@
 //! - [Pickle], a format common in the Python world.
 //! - [Hjson], a variant of JSON designed to be readable and writable by humans.
 //! - [BSON], the data storage and network transfer format used by MongoDB.
+//! - [Avro], a binary format used within Apache Hadoop, with support for schema
+//!   definition.
 //! - [URL], the x-www-form-urlencoded format.
 //! - [XML], the flexible machine-friendly W3C standard.
 //!   *(deserialization only)*
@@ -69,6 +71,7 @@
 //! [Pickle]: https://github.com/birkenfeld/serde-pickle
 //! [Hjson]: https://github.com/laktak/hjson-rust
 //! [BSON]: https://github.com/zonyitoo/bson-rs
+//! [Avro]: https://github.com/flavray/avro-rs
 //! [URL]: https://github.com/nox/serde_urlencoded
 //! [XML]: https://github.com/RReverser/serde-xml-rs
 //! [Envy]: https://github.com/softprops/envy
@@ -79,14 +82,14 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.45")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.66")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Unstable functionality only if the user asks for it. For tracking and
 // discussion of these features please refer to this issue:
 //
 //    https://github.com/serde-rs/serde/issues/812
-#![cfg_attr(feature = "unstable", feature(nonzero, specialization))]
+#![cfg_attr(feature = "unstable", feature(specialization, never_type))]
 #![cfg_attr(feature = "alloc", feature(alloc))]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Whitelisted clippy lints
@@ -130,9 +133,6 @@
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
-#[cfg(all(feature = "unstable", feature = "std"))]
-extern crate core;
-
 /// A facade around all the types we need from the `std`, `core`, and `alloc`
 /// crates. This avoids elaborate import wrangling having to happen in every
 /// module.
@@ -144,7 +144,7 @@ mod lib {
         pub use std::*;
     }
 
-    pub use self::core::{cmp, iter, mem, ops, slice, str};
+    pub use self::core::{cmp, iter, mem, num, ops, slice, str};
     pub use self::core::{f32, f64};
     pub use self::core::{i16, i32, i64, i8, isize};
     pub use self::core::{u16, u32, u64, u8, usize};
@@ -179,14 +179,14 @@ mod lib {
     pub use std::boxed::Box;
 
     #[cfg(all(feature = "rc", feature = "alloc", not(feature = "std")))]
-    pub use alloc::rc::Rc;
+    pub use alloc::rc::{Rc, Weak as RcWeak};
     #[cfg(all(feature = "rc", feature = "std"))]
-    pub use std::rc::Rc;
+    pub use std::rc::{Rc, Weak as RcWeak};
 
     #[cfg(all(feature = "rc", feature = "alloc", not(feature = "std")))]
-    pub use alloc::arc::Arc;
+    pub use alloc::arc::{Arc, Weak as ArcWeak};
     #[cfg(all(feature = "rc", feature = "std"))]
-    pub use std::sync::Arc;
+    pub use std::sync::{Arc, Weak as ArcWeak};
 
     #[cfg(all(feature = "alloc", not(feature = "std")))]
     pub use alloc::{BTreeMap, BTreeSet, BinaryHeap, LinkedList, VecDeque};
@@ -211,14 +211,10 @@ mod lib {
     #[cfg(feature = "std")]
     pub use std::sync::{Mutex, RwLock};
     #[cfg(feature = "std")]
-    pub use std::time::{Duration, SystemTime, UNIX_EPOCH};
+    pub use std::time::{SystemTime, UNIX_EPOCH};
 
-    #[cfg(feature = "unstable")]
-    #[allow(deprecated)]
-    pub use core::nonzero::{NonZero, Zeroable};
-
-    #[cfg(feature = "unstable")]
-    pub use core::num::{NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize};
+    #[cfg(any(core_duration, feature = "std"))]
+    pub use self::core::time::Duration;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -226,6 +222,9 @@ mod lib {
 #[macro_use]
 mod macros;
 
+#[macro_use]
+mod integer128;
+
 pub mod de;
 pub mod ser;
 

serde/src/macros.rs

@@ -31,21 +31,23 @@
 /// #     type Error = value::Error;
 /// #
 /// #     fn deserialize_any<V>(self, _: V) -> Result<V::Value, Self::Error>
-/// #         where V: Visitor<'de>
+/// #     where
+/// #         V: Visitor<'de>,
 /// #     {
 /// #         unimplemented!()
 /// #     }
 /// #
 /// #[inline]
 /// fn deserialize_bool<V>(self, visitor: V) -> Result<V::Value, Self::Error>
-///     where V: Visitor<'de>
+/// where
+///     V: Visitor<'de>,
 /// {
 ///     self.deserialize_any(visitor)
 /// }
 /// #
 /// #     forward_to_deserialize_any! {
-/// #         i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-/// #         byte_buf option unit unit_struct newtype_struct seq tuple
+/// #         i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+/// #         bytes byte_buf option unit unit_struct newtype_struct seq tuple
 /// #         tuple_struct map struct enum identifier ignored_any
 /// #     }
 /// # }
@@ -69,7 +71,8 @@
 /// #   type Error = value::Error;
 /// #
 ///     fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
-///         where V: Visitor<'de>
+///     where
+///         V: Visitor<'de>,
 ///     {
 ///         /* ... */
 /// #       let _ = visitor;
@@ -77,8 +80,8 @@
 ///     }
 ///
 ///     forward_to_deserialize_any! {
-///         bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-///         byte_buf option unit unit_struct newtype_struct seq tuple
+///         bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+///         bytes byte_buf option unit unit_struct newtype_struct seq tuple
 ///         tuple_struct map struct enum identifier ignored_any
 ///     }
 /// }
@@ -105,16 +108,17 @@
 /// #     type Error = value::Error;
 /// #
 /// #     fn deserialize_any<W>(self, visitor: W) -> Result<W::Value, Self::Error>
-/// #         where W: Visitor<'q>
+/// #     where
+/// #         W: Visitor<'q>,
 /// #     {
 /// #         unimplemented!()
 /// #     }
 /// #
 /// forward_to_deserialize_any! {
 ///     <W: Visitor<'q>>
-///     bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-///     byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-///     map struct enum identifier ignored_any
+///     bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+///     bytes byte_buf option unit unit_struct newtype_struct seq tuple
+///     tuple_struct map struct enum identifier ignored_any
 /// }
 /// # }
 /// #
@@ -170,6 +174,11 @@ macro_rules! forward_to_deserialize_any_helper {
     (i64<$l:tt, $v:ident>) => {
         forward_to_deserialize_any_method!{deserialize_i64<$l, $v>()}
     };
+    (i128<$l:tt, $v:ident>) => {
+        serde_if_integer128! {
+            forward_to_deserialize_any_method!{deserialize_i128<$l, $v>()}
+        }
+    };
     (u8<$l:tt, $v:ident>) => {
         forward_to_deserialize_any_method!{deserialize_u8<$l, $v>()}
     };
@@ -182,6 +191,11 @@ macro_rules! forward_to_deserialize_any_helper {
     (u64<$l:tt, $v:ident>) => {
         forward_to_deserialize_any_method!{deserialize_u64<$l, $v>()}
     };
+    (u128<$l:tt, $v:ident>) => {
+        serde_if_integer128! {
+            forward_to_deserialize_any_method!{deserialize_u128<$l, $v>()}
+        }
+    };
     (f32<$l:tt, $v:ident>) => {
         forward_to_deserialize_any_method!{deserialize_f32<$l, $v>()}
     };

serde/src/private/de.rs

@@ -14,10 +14,11 @@ use de::{Deserialize, DeserializeSeed, Deserializer, Error, IntoDeserializer, Vi
 use de::{MapAccess, Unexpected};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-pub use self::content::{Content, ContentDeserializer, ContentRefDeserializer, EnumDeserializer,
-                        InternallyTaggedUnitVisitor, TagContentOtherField,
-                        TagContentOtherFieldVisitor, TagOrContentField, TagOrContentFieldVisitor,
-                        TaggedContentVisitor, UntaggedUnitVisitor};
+pub use self::content::{
+    Content, ContentDeserializer, ContentRefDeserializer, EnumDeserializer,
+    InternallyTaggedUnitVisitor, TagContentOtherField, TagContentOtherFieldVisitor,
+    TagOrContentField, TagOrContentFieldVisitor, TaggedContentVisitor, UntaggedUnitVisitor,
+};
 
 /// If the missing field is of type `Option<T>` then treat is as `None`,
 /// otherwise it is an error.
@@ -49,9 +50,9 @@ where
         }
 
         forward_to_deserialize_any! {
-            bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-            byte_buf unit unit_struct newtype_struct seq tuple tuple_struct map
-            struct enum identifier ignored_any
+            bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+            bytes byte_buf unit unit_struct newtype_struct seq tuple
+            tuple_struct map struct enum identifier ignored_any
         }
     }
 
@@ -229,8 +230,10 @@ mod content {
     use lib::*;
 
     use super::size_hint;
-    use de::{self, Deserialize, DeserializeSeed, Deserializer, EnumAccess, Expected, MapAccess,
-             SeqAccess, Unexpected, Visitor};
+    use de::{
+        self, Deserialize, DeserializeSeed, Deserializer, EnumAccess, Expected, MapAccess,
+        SeqAccess, Unexpected, Visitor,
+    };
 
     /// Used from generated code to buffer the contents of the Deserializer when
     /// deserializing untagged enums and internally tagged enums.
@@ -273,6 +276,8 @@ mod content {
             match *self {
                 Content::Str(x) => Some(x),
                 Content::String(ref x) => Some(x),
+                Content::Bytes(x) => str::from_utf8(x).ok(),
+                Content::ByteBuf(ref x) => str::from_utf8(x).ok(),
                 _ => None,
             }
         }
@@ -1420,6 +1425,8 @@ mod content {
             match self.content {
                 Content::String(v) => visitor.visit_string(v),
                 Content::Str(v) => visitor.visit_borrowed_str(v),
+                Content::ByteBuf(v) => visitor.visit_byte_buf(v),
+                Content::Bytes(v) => visitor.visit_borrowed_bytes(v),
                 _ => Err(self.invalid_type(&visitor)),
             }
         }
@@ -1611,8 +1618,8 @@ mod content {
         }
 
         forward_to_deserialize_any! {
-            bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-            byte_buf option unit unit_struct newtype_struct seq tuple
+            bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+            bytes byte_buf option unit unit_struct newtype_struct seq tuple
             tuple_struct map struct enum identifier ignored_any
         }
     }
@@ -1709,8 +1716,8 @@ mod content {
         }
 
         forward_to_deserialize_any! {
-            bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-            byte_buf option unit unit_struct newtype_struct seq tuple
+            bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+            bytes byte_buf option unit unit_struct newtype_struct seq tuple
             tuple_struct map struct enum identifier ignored_any
         }
     }
@@ -2120,6 +2127,8 @@ mod content {
             match *self.content {
                 Content::String(ref v) => visitor.visit_str(v),
                 Content::Str(v) => visitor.visit_borrowed_str(v),
+                Content::ByteBuf(ref v) => visitor.visit_bytes(v),
+                Content::Bytes(v) => visitor.visit_borrowed_bytes(v),
                 _ => Err(self.invalid_type(&visitor)),
             }
         }
@@ -2297,8 +2306,8 @@ mod content {
         }
 
         forward_to_deserialize_any! {
-            bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-            byte_buf option unit unit_struct newtype_struct seq tuple
+            bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+            bytes byte_buf option unit unit_struct newtype_struct seq tuple
             tuple_struct map struct enum identifier ignored_any
         }
     }
@@ -2314,7 +2323,8 @@ mod content {
             T: de::DeserializeSeed<'de>,
         {
             match self.iter.next() {
-                Some(value) => seed.deserialize(ContentRefDeserializer::new(value))
+                Some(value) => seed
+                    .deserialize(ContentRefDeserializer::new(value))
                     .map(Some),
                 None => Ok(None),
             }
@@ -2396,8 +2406,8 @@ mod content {
         }
 
         forward_to_deserialize_any! {
-            bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-            byte_buf option unit unit_struct newtype_struct seq tuple
+            bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+            bytes byte_buf option unit unit_struct newtype_struct seq tuple
             tuple_struct map struct enum identifier ignored_any
         }
     }
@@ -2568,9 +2578,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct enum identifier ignored_any
     }
 }
 
@@ -2607,9 +2617,9 @@ where
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct enum identifier ignored_any
     }
 }
 
@@ -2637,6 +2647,30 @@ pub struct FlatMapDeserializer<'a, 'de: 'a, E>(
     pub PhantomData<E>,
 );
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, 'de, E> FlatMapDeserializer<'a, 'de, E>
+where
+    E: Error,
+{
+    fn deserialize_other<V>() -> Result<V, E> {
+        Err(Error::custom("can only flatten structs and maps"))
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+macro_rules! forward_to_deserialize_other {
+    ($($func:ident ( $($arg:ty),* ))*) => {
+        $(
+            fn $func<V>(self, $(_: $arg,)* _visitor: V) -> Result<V::Value, Self::Error>
+            where
+                V: Visitor<'de>,
+            {
+                Self::deserialize_other()
+            }
+        )*
+    }
+}
+
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'a, 'de, E> Deserializer<'de> for FlatMapDeserializer<'a, 'de, E>
 where
@@ -2644,11 +2678,15 @@ where
 {
     type Error = E;
 
-    fn deserialize_any<V>(self, _: V) -> Result<V::Value, Self::Error>
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
     where
         V: Visitor<'de>,
     {
-        Err(Error::custom("can only flatten structs and maps"))
+        visitor.visit_map(FlatInternallyTaggedAccess {
+            iter: self.0.iter_mut(),
+            pending: None,
+            _marker: PhantomData,
+        })
     }
 
     fn deserialize_enum<V>(
@@ -2685,7 +2723,7 @@ where
     where
         V: Visitor<'de>,
     {
-        visitor.visit_map(FlatMapAccess::new(self.0.iter_mut(), None))
+        visitor.visit_map(FlatMapAccess::new(self.0.iter()))
     }
 
     fn deserialize_struct<V>(
@@ -2697,7 +2735,7 @@ where
     where
         V: Visitor<'de>,
     {
-        visitor.visit_map(FlatMapAccess::new(self.0.iter_mut(), Some(fields)))
+        visitor.visit_map(FlatStructAccess::new(self.0.iter_mut(), fields))
     }
 
     fn deserialize_newtype_struct<V>(self, _name: &str, visitor: V) -> Result<V::Value, Self::Error>
@@ -2707,31 +2745,58 @@ where
         visitor.visit_newtype_struct(self)
     }
 
-    forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct seq tuple tuple_struct identifier
-        ignored_any
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        match visitor.__private_visit_untagged_option(self) {
+            Ok(value) => Ok(value),
+            Err(()) => Self::deserialize_other(),
+        }
+    }
+
+    forward_to_deserialize_other! {
+        deserialize_bool()
+        deserialize_i8()
+        deserialize_i16()
+        deserialize_i32()
+        deserialize_i64()
+        deserialize_u8()
+        deserialize_u16()
+        deserialize_u32()
+        deserialize_u64()
+        deserialize_f32()
+        deserialize_f64()
+        deserialize_char()
+        deserialize_str()
+        deserialize_string()
+        deserialize_bytes()
+        deserialize_byte_buf()
+        deserialize_unit()
+        deserialize_unit_struct(&'static str)
+        deserialize_seq()
+        deserialize_tuple(usize)
+        deserialize_tuple_struct(&'static str, usize)
+        deserialize_identifier()
+        deserialize_ignored_any()
     }
 }
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 pub struct FlatMapAccess<'a, 'de: 'a, E> {
-    iter: slice::IterMut<'a, Option<(Content<'de>, Content<'de>)>>,
-    pending_content: Option<Content<'de>>,
-    fields: Option<&'static [&'static str]>,
+    iter: slice::Iter<'a, Option<(Content<'de>, Content<'de>)>>,
+    pending_content: Option<&'a Content<'de>>,
     _marker: PhantomData<E>,
 }
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'a, 'de, E> FlatMapAccess<'a, 'de, E> {
     fn new(
-        iter: slice::IterMut<'a, Option<(Content<'de>, Content<'de>)>>,
-        fields: Option<&'static [&'static str]>,
+        iter: slice::Iter<'a, Option<(Content<'de>, Content<'de>)>>,
     ) -> FlatMapAccess<'a, 'de, E> {
         FlatMapAccess {
             iter: iter,
             pending_content: None,
-            fields: fields,
             _marker: PhantomData,
         }
     }
@@ -2744,6 +2809,61 @@ where
 {
     type Error = E;
 
+    fn next_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+    where
+        T: DeserializeSeed<'de>,
+    {
+        while let Some(item) = self.iter.next() {
+            // Items in the vector are nulled out when used by a struct.
+            if let Some((ref key, ref content)) = *item {
+                self.pending_content = Some(content);
+                return seed.deserialize(ContentRefDeserializer::new(key)).map(Some);
+            }
+        }
+        Ok(None)
+    }
+
+    fn next_value_seed<T>(&mut self, seed: T) -> Result<T::Value, Self::Error>
+    where
+        T: DeserializeSeed<'de>,
+    {
+        match self.pending_content.take() {
+            Some(value) => seed.deserialize(ContentRefDeserializer::new(value)),
+            None => Err(Error::custom("value is missing")),
+        }
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+pub struct FlatStructAccess<'a, 'de: 'a, E> {
+    iter: slice::IterMut<'a, Option<(Content<'de>, Content<'de>)>>,
+    pending_content: Option<Content<'de>>,
+    fields: &'static [&'static str],
+    _marker: PhantomData<E>,
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, 'de, E> FlatStructAccess<'a, 'de, E> {
+    fn new(
+        iter: slice::IterMut<'a, Option<(Content<'de>, Content<'de>)>>,
+        fields: &'static [&'static str],
+    ) -> FlatStructAccess<'a, 'de, E> {
+        FlatStructAccess {
+            iter: iter,
+            pending_content: None,
+            fields: fields,
+            _marker: PhantomData,
+        }
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, 'de, E> MapAccess<'de> for FlatStructAccess<'a, 'de, E>
+where
+    E: Error,
+{
+    type Error = E;
+
     fn next_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
     where
         T: DeserializeSeed<'de>,
@@ -2754,14 +2874,7 @@ where
             // about.  In case we do not know which fields we want, we take them all.
             let use_item = match *item {
                 None => false,
-                Some((ref c, _)) => {
-                    c.as_str()
-                        .map_or(self.fields.is_none(), |key| match self.fields {
-                            None => true,
-                            Some(fields) if fields.contains(&key) => true,
-                            _ => false,
-                        })
-                }
+                Some((ref c, _)) => c.as_str().map_or(false, |key| self.fields.contains(&key)),
             };
 
             if use_item {
@@ -2783,3 +2896,46 @@ where
         }
     }
 }
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+pub struct FlatInternallyTaggedAccess<'a, 'de: 'a, E> {
+    iter: slice::IterMut<'a, Option<(Content<'de>, Content<'de>)>>,
+    pending: Option<&'a Content<'de>>,
+    _marker: PhantomData<E>,
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, 'de, E> MapAccess<'de> for FlatInternallyTaggedAccess<'a, 'de, E>
+where
+    E: Error,
+{
+    type Error = E;
+
+    fn next_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+    where
+        T: DeserializeSeed<'de>,
+    {
+        match self.iter.next() {
+            Some(item) => {
+                // Do not take(), instead borrow this entry. The internally tagged
+                // enum does its own buffering so we can't tell whether this entry
+                // is going to be consumed. Borrowing here leaves the entry
+                // available for later flattened fields.
+                let (ref key, ref content) = *item.as_ref().unwrap();
+                self.pending = Some(content);
+                seed.deserialize(ContentRefDeserializer::new(key)).map(Some)
+            }
+            None => Ok(None),
+        }
+    }
+
+    fn next_value_seed<T>(&mut self, seed: T) -> Result<T::Value, Self::Error>
+    where
+        T: DeserializeSeed<'de>,
+    {
+        match self.pending.take() {
+            Some(value) => seed.deserialize(ContentRefDeserializer::new(value)),
+            None => panic!("value is missing"),
+        }
+    }
+}

serde/src/private/ser.rs

@@ -11,8 +11,9 @@ use lib::*;
 use ser::{self, Impossible, Serialize, SerializeMap, SerializeStruct, Serializer};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-use self::content::{Content, ContentSerializer, SerializeStructVariantAsMapValue,
-                    SerializeTupleVariantAsMapValue};
+use self::content::{
+    Content, ContentSerializer, SerializeStructVariantAsMapValue, SerializeTupleVariantAsMapValue,
+};
 
 /// Used to check that serde(getter) attributes return the expected type.
 /// Not public API.
@@ -946,7 +947,8 @@ mod content {
         where
             T: Serialize,
         {
-            let key = self.key
+            let key = self
+                .key
                 .take()
                 .expect("serialize_value called before serialize_key");
             let value = try!(value.serialize(ContentSerializer::<E>::new()));
@@ -1121,14 +1123,14 @@ where
     }
 
     fn serialize_none(self) -> Result<Self::Ok, Self::Error> {
-        Err(self.bad_type(Unsupported::Optional))
+        Ok(())
     }
 
-    fn serialize_some<T: ?Sized>(self, _: &T) -> Result<Self::Ok, Self::Error>
+    fn serialize_some<T: ?Sized>(self, value: &T) -> Result<Self::Ok, Self::Error>
     where
         T: Serialize,
     {
-        Err(self.bad_type(Unsupported::Optional))
+        value.serialize(self)
     }
 
     fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {

serde/src/ser/impls.rs

@@ -8,10 +8,7 @@
 
 use lib::*;
 
-use ser::{Serialize, SerializeTuple, Serializer};
-
-#[cfg(feature = "std")]
-use ser::Error;
+use ser::{Error, Serialize, SerializeTuple, Serializer};
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -44,6 +41,11 @@ primitive_impl!(f32, serialize_f32);
 primitive_impl!(f64, serialize_f64);
 primitive_impl!(char, serialize_char);
 
+serde_if_integer128! {
+    primitive_impl!(i128, serialize_i128);
+    primitive_impl!(u128, serialize_u128);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 impl Serialize for str {
@@ -245,6 +247,16 @@ impl Serialize for () {
     }
 }
 
+#[cfg(feature = "unstable")]
+impl Serialize for ! {
+    fn serialize<S>(&self, _serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        *self
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 macro_rules! tuple_impls {
@@ -374,25 +386,45 @@ deref_impl!(<'a, T: ?Sized> Serialize for Cow<'a, T> where T: Serialize + ToOwne
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(feature = "unstable")]
-#[allow(deprecated)]
-impl<T> Serialize for NonZero<T>
+/// This impl requires the [`"rc"`] Cargo feature of Serde.
+///
+/// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
+impl<T: ?Sized> Serialize for RcWeak<T>
 where
-    T: Serialize + Zeroable + Clone,
+    T: Serialize,
 {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: Serializer,
     {
-        self.clone().get().serialize(serializer)
+        self.upgrade().serialize(serializer)
     }
 }
 
+/// This impl requires the [`"rc"`] Cargo feature of Serde.
+///
+/// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
+impl<T: ?Sized> Serialize for ArcWeak<T>
+where
+    T: Serialize,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        self.upgrade().serialize(serializer)
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 macro_rules! nonzero_integers {
     ( $( $T: ident, )+ ) => {
         $(
-            #[cfg(feature = "unstable")]
-            impl Serialize for $T {
+            #[cfg(num_nonzero)]
+            impl Serialize for num::$T {
                 fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
                 where
                     S: Serializer,
@@ -434,7 +466,10 @@ where
     where
         S: Serializer,
     {
-        self.borrow().serialize(serializer)
+        match self.try_borrow() {
+            Ok(value) => value.serialize(serializer),
+            Err(_) => Err(S::Error::custom("already mutably borrowed")),
+        }
     }
 }
 
@@ -492,7 +527,7 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(feature = "std")]
+#[cfg(any(core_duration, feature = "std"))]
 impl Serialize for Duration {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -515,7 +550,8 @@ impl Serialize for SystemTime {
         S: Serializer,
     {
         use super::SerializeStruct;
-        let duration_since_epoch = self.duration_since(UNIX_EPOCH)
+        let duration_since_epoch = self
+            .duration_since(UNIX_EPOCH)
             .expect("SystemTime must be later than UNIX_EPOCH");
         let mut state = try!(serializer.serialize_struct("SystemTime", 2));
         try!(state.serialize_field("secs_since_epoch", &duration_since_epoch.as_secs()));

serde/src/ser/impossible.rs

@@ -10,8 +10,10 @@
 
 use lib::*;
 
-use ser::{self, Serialize, SerializeMap, SerializeSeq, SerializeStruct, SerializeStructVariant,
-          SerializeTuple, SerializeTupleStruct, SerializeTupleVariant};
+use ser::{
+    self, Serialize, SerializeMap, SerializeSeq, SerializeStruct, SerializeStructVariant,
+    SerializeTuple, SerializeTupleStruct, SerializeTupleVariant,
+};
 
 /// Helper type for implementing a `Serializer` that does not support
 /// serializing one of the compound types.

serde/src/ser/mod.rs

@@ -48,15 +48,15 @@
 //!
 //!  - **Primitive types**:
 //!    - bool
-//!    - i8, i16, i32, i64, isize
-//!    - u8, u16, u32, u64, usize
+//!    - i8, i16, i32, i64, i128, isize
+//!    - u8, u16, u32, u64, u128, usize
 //!    - f32, f64
 //!    - char
 //!    - str
 //!    - &T and &mut T
 //!  - **Compound types**:
-//!    - [T]
-//!    - [T; 0] through [T; 32]
+//!    - \[T\]
+//!    - \[T; 0\] through \[T; 32\]
 //!    - tuples up to size 16
 //!  - **Common standard library types**:
 //!    - String
@@ -81,7 +81,6 @@
 //!    - LinkedList\<T\>
 //!    - VecDeque\<T\>
 //!    - Vec\<T\>
-//!    - EnumSet\<T\> (unstable)
 //!  - **FFI types**:
 //!    - CStr
 //!    - CString
@@ -93,8 +92,8 @@
 //!    - Path
 //!    - PathBuf
 //!    - Range\<T\>
-//!    - NonZero\<T\> (unstable, deprecated)
-//!    - num::NonZero* (unstable)
+//!    - num::NonZero*
+//!    - `!` *(unstable)*
 //!  - **Net types**:
 //!    - IpAddr
 //!    - Ipv4Addr
@@ -129,6 +128,13 @@ macro_rules! declare_error_trait {
         /// Trait used by `Serialize` implementations to generically construct
         /// errors belonging to the `Serializer` against which they are
         /// currently running.
+        ///
+        /// # Example implementation
+        ///
+        /// The [example data format] presented on the website shows an error
+        /// type appropriate for a basic JSON data format.
+        ///
+        /// [example data format]: https://serde.rs/data-format.html
         pub trait Error: Sized $(+ $($supertrait)::+)* {
             /// Used when a [`Serialize`] implementation encounters any error
             /// while serializing a type.
@@ -152,7 +158,8 @@ macro_rules! declare_error_trait {
             ///
             /// impl Serialize for Path {
             ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-            ///         where S: Serializer
+            ///     where
+            ///         S: Serializer,
             ///     {
             ///         match self.to_str() {
             ///             Some(s) => serializer.serialize_str(s),
@@ -223,7 +230,8 @@ pub trait Serialize {
     /// // This is what #[derive(Serialize)] would generate.
     /// impl Serialize for Person {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         let mut s = serializer.serialize_struct("Person", 3)?;
     ///         s.serialize_field("name", &self.name)?;
@@ -244,27 +252,27 @@ pub trait Serialize {
 
 /// A **data format** that can serialize any data structure supported by Serde.
 ///
-/// The role of this trait is to define the serialization half of the Serde data
-/// model, which is a way to categorize every Rust data structure into one of 27
-/// possible types. Each method of the `Serializer` trait corresponds to one of
-/// the types of the data model.
+/// The role of this trait is to define the serialization half of the [Serde
+/// data model], which is a way to categorize every Rust data structure into one
+/// of 29 possible types. Each method of the `Serializer` trait corresponds to
+/// one of the types of the data model.
 ///
 /// Implementations of `Serialize` map themselves into this data model by
 /// invoking exactly one of the `Serializer` methods.
 ///
 /// The types that make up the Serde data model are:
 ///
-///  - **12 primitive types**
+///  - **14 primitive types**
 ///    - bool
-///    - i8, i16, i32, i64
-///    - u8, u16, u32, u64
+///    - i8, i16, i32, i64, i128
+///    - u8, u16, u32, u64, u128
 ///    - f32, f64
 ///    - char
 ///  - **string**
 ///    - UTF-8 bytes with a length and no null terminator.
 ///    - When serializing, all strings are handled equally. When deserializing,
 ///      there are three flavors of strings: transient, owned, and borrowed.
-///  - **byte array** - [u8]
+///  - **byte array** - \[u8\]
 ///    - Similar to strings, during deserialization byte arrays can be transient,
 ///      owned, or borrowed.
 ///  - **option**
@@ -309,6 +317,15 @@ pub trait Serialize {
 /// is the `serde_json::value::Serializer` (distinct from the main `serde_json`
 /// serializer) that produces a `serde_json::Value` data structure in memory as
 /// output.
+///
+/// [Serde data model]: https://serde.rs/data-model.html
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website contains example code for
+/// a basic JSON `Serializer`.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait Serializer: Sized {
     /// The output type produced by this `Serializer` during successful
     /// serialization. Most serializers that produce text or binary output
@@ -377,7 +394,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for bool {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_bool(*self)
     ///     }
@@ -403,7 +421,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for i8 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_i8(*self)
     ///     }
@@ -429,7 +448,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for i16 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_i16(*self)
     ///     }
@@ -455,7 +475,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for i32 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_i32(*self)
     ///     }
@@ -477,7 +498,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for i64 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_i64(*self)
     ///     }
@@ -487,6 +509,37 @@ pub trait Serializer: Sized {
     /// ```
     fn serialize_i64(self, v: i64) -> Result<Self::Ok, Self::Error>;
 
+    serde_if_integer128! {
+        /// Serialize an `i128` value.
+        ///
+        /// ```rust
+        /// # #[macro_use]
+        /// # extern crate serde;
+        /// #
+        /// # use serde::Serializer;
+        /// #
+        /// # __private_serialize!();
+        /// #
+        /// impl Serialize for i128 {
+        ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        ///     where
+        ///         S: Serializer,
+        ///     {
+        ///         serializer.serialize_i128(*self)
+        ///     }
+        /// }
+        /// #
+        /// # fn main() {}
+        /// ```
+        ///
+        /// This method is available only on Rust compiler versions >=1.26. The
+        /// default behavior unconditionally returns an error.
+        fn serialize_i128(self, v: i128) -> Result<Self::Ok, Self::Error> {
+            let _ = v;
+            Err(Error::custom("i128 is not supported"))
+        }
+    }
+
     /// Serialize a `u8` value.
     ///
     /// If the format does not differentiate between `u8` and `u64`, a
@@ -503,7 +556,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for u8 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_u8(*self)
     ///     }
@@ -529,7 +583,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for u16 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_u16(*self)
     ///     }
@@ -555,7 +610,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for u32 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_u32(*self)
     ///     }
@@ -577,7 +633,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for u64 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_u64(*self)
     ///     }
@@ -587,6 +644,37 @@ pub trait Serializer: Sized {
     /// ```
     fn serialize_u64(self, v: u64) -> Result<Self::Ok, Self::Error>;
 
+    serde_if_integer128! {
+        /// Serialize a `u128` value.
+        ///
+        /// ```rust
+        /// # #[macro_use]
+        /// # extern crate serde;
+        /// #
+        /// # use serde::Serializer;
+        /// #
+        /// # __private_serialize!();
+        /// #
+        /// impl Serialize for u128 {
+        ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        ///     where
+        ///         S: Serializer,
+        ///     {
+        ///         serializer.serialize_u128(*self)
+        ///     }
+        /// }
+        /// #
+        /// # fn main() {}
+        /// ```
+        ///
+        /// This method is available only on Rust compiler versions >=1.26. The
+        /// default behavior unconditionally returns an error.
+        fn serialize_u128(self, v: u128) -> Result<Self::Ok, Self::Error> {
+            let _ = v;
+            Err(Error::custom("u128 is not supported"))
+        }
+    }
+
     /// Serialize an `f32` value.
     ///
     /// If the format does not differentiate between `f32` and `f64`, a
@@ -603,7 +691,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for f32 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_f32(*self)
     ///     }
@@ -625,7 +714,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for f64 {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_f64(*self)
     ///     }
@@ -650,7 +740,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for char {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_char(*self)
     ///     }
@@ -672,7 +763,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for str {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_str(self)
     ///     }
@@ -737,10 +829,12 @@ pub trait Serializer: Sized {
     /// # use Option::{Some, None};
     /// #
     /// impl<T> Serialize for Option<T>
-    ///     where T: Serialize
+    /// where
+    ///     T: Serialize,
     /// {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         match *self {
     ///             Some(ref value) => serializer.serialize_some(value),
@@ -770,10 +864,12 @@ pub trait Serializer: Sized {
     /// # use Option::{Some, None};
     /// #
     /// impl<T> Serialize for Option<T>
-    ///     where T: Serialize
+    /// where
+    ///     T: Serialize,
     /// {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         match *self {
     ///             Some(ref value) => serializer.serialize_some(value),
@@ -802,7 +898,8 @@ pub trait Serializer: Sized {
     /// #
     /// impl Serialize for () {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_unit()
     ///     }
@@ -823,7 +920,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for Nothing {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_unit_struct("Nothing")
     ///     }
@@ -847,7 +945,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for E {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         match *self {
     ///             E::A => serializer.serialize_unit_variant("E", 0, "A"),
@@ -876,7 +975,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for Millimeters {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.serialize_newtype_struct("Millimeters", &self.0)
     ///     }
@@ -906,7 +1006,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for E {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         match *self {
     ///             E::M(ref s) => serializer.serialize_newtype_variant("E", 0, "M", s),
@@ -956,10 +1057,12 @@ pub trait Serializer: Sized {
     /// use serde::ser::{Serialize, Serializer, SerializeSeq};
     ///
     /// impl<T> Serialize for Vec<T>
-    ///     where T: Serialize
+    /// where
+    ///     T: Serialize,
     /// {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         let mut seq = serializer.serialize_seq(Some(self.len()))?;
     ///         for element in self {
@@ -988,12 +1091,14 @@ pub trait Serializer: Sized {
     /// # struct Tuple3<A, B, C>(A, B, C);
     /// #
     /// # impl<A, B, C> Serialize for Tuple3<A, B, C>
-    ///     where A: Serialize,
-    ///           B: Serialize,
-    ///           C: Serialize
+    /// where
+    ///     A: Serialize,
+    ///     B: Serialize,
+    ///     C: Serialize,
     /// {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         let mut tup = serializer.serialize_tuple(3)?;
     ///         tup.serialize_element(&self.0)?;
@@ -1012,7 +1117,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for Vram {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         let mut seq = serializer.serialize_tuple(VRAM_SIZE)?;
     ///         for element in &self.0[..] {
@@ -1038,7 +1144,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for Rgb {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         let mut ts = serializer.serialize_tuple_struct("Rgb", 3)?;
     ///         ts.serialize_field(&self.0)?;
@@ -1072,7 +1179,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for E {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         match *self {
     ///             E::T(ref a, ref b) => {
@@ -1130,11 +1238,13 @@ pub trait Serializer: Sized {
     /// use serde::ser::{Serialize, Serializer, SerializeMap};
     ///
     /// impl<K, V> Serialize for HashMap<K, V>
-    ///     where K: Serialize,
-    ///           V: Serialize
+    /// where
+    ///     K: Serialize,
+    ///     V: Serialize,
     /// {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         let mut map = serializer.serialize_map(Some(self.len()))?;
     ///         for (k, v) in self {
@@ -1164,7 +1274,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for Rgb {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         let mut rgb = serializer.serialize_struct("Rgb", 3)?;
     ///         rgb.serialize_field("r", &self.r)?;
@@ -1197,7 +1308,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for E {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         match *self {
     ///             E::S { ref r, ref g, ref b } => {
@@ -1234,7 +1346,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for SecretlyOneHigher {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.collect_seq(self.data.iter().map(|x| x + 1))
     ///     }
@@ -1272,7 +1385,8 @@ pub trait Serializer: Sized {
     /// // Serializes as a map in which the values are all unit.
     /// impl Serialize for MapToUnit {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.collect_map(self.keys.iter().map(|k| (k, ())))
     ///     }
@@ -1312,7 +1426,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for DateTime {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.collect_str(&format_args!("{:?}{:?}",
     ///                                              self.naive_local(),
@@ -1352,7 +1467,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for DateTime {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         serializer.collect_str(&format_args!("{:?}{:?}",
     ///                                              self.naive_local(),
@@ -1393,7 +1509,8 @@ pub trait Serializer: Sized {
     ///
     /// impl Serialize for Timestamp {
     ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    ///         where S: Serializer
+    ///     where
+    ///         S: Serializer,
     ///     {
     ///         if serializer.is_human_readable() {
     ///             // Serialize to a human-readable string "2015-05-15T17:01:00Z".
@@ -1420,6 +1537,8 @@ pub trait Serializer: Sized {
 
 /// Returned from `Serializer::serialize_seq`.
 ///
+/// # Example use
+///
 /// ```rust
 /// # use std::marker::PhantomData;
 /// #
@@ -1442,10 +1561,12 @@ pub trait Serializer: Sized {
 /// use serde::ser::{Serialize, Serializer, SerializeSeq};
 ///
 /// impl<T> Serialize for Vec<T>
-///     where T: Serialize
+/// where
+///     T: Serialize,
 /// {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer
+///     where
+///         S: Serializer,
 ///     {
 ///         let mut seq = serializer.serialize_seq(Some(self.len()))?;
 ///         for element in self {
@@ -1455,6 +1576,13 @@ pub trait Serializer: Sized {
 ///     }
 /// }
 /// ```
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `SerializeSeq` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait SerializeSeq {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1473,6 +1601,8 @@ pub trait SerializeSeq {
 
 /// Returned from `Serializer::serialize_tuple`.
 ///
+/// # Example use
+///
 /// ```rust
 /// use serde::ser::{Serialize, Serializer, SerializeTuple};
 ///
@@ -1485,12 +1615,14 @@ pub trait SerializeSeq {
 /// # struct Tuple3<A, B, C>(A, B, C);
 /// #
 /// # impl<A, B, C> Serialize for Tuple3<A, B, C>
-///     where A: Serialize,
-///           B: Serialize,
-///           C: Serialize
+/// where
+///     A: Serialize,
+///     B: Serialize,
+///     C: Serialize,
 /// {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer
+///     where
+///         S: Serializer,
 ///     {
 ///         let mut tup = serializer.serialize_tuple(3)?;
 ///         tup.serialize_element(&self.0)?;
@@ -1529,10 +1661,12 @@ pub trait SerializeSeq {
 /// # }
 /// #
 /// # impl<T> Serialize for Array<T>
-///     where T: Serialize
+/// where
+///     T: Serialize,
 /// {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer
+///     where
+///         S: Serializer,
 ///     {
 ///         let mut seq = serializer.serialize_tuple(16)?;
 ///         for element in self {
@@ -1542,6 +1676,13 @@ pub trait SerializeSeq {
 ///     }
 /// }
 /// ```
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `SerializeTuple` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait SerializeTuple {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1560,6 +1701,8 @@ pub trait SerializeTuple {
 
 /// Returned from `Serializer::serialize_tuple_struct`.
 ///
+/// # Example use
+///
 /// ```rust
 /// use serde::ser::{Serialize, Serializer, SerializeTupleStruct};
 ///
@@ -1567,7 +1710,8 @@ pub trait SerializeTuple {
 ///
 /// impl Serialize for Rgb {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer
+///     where
+///         S: Serializer,
 ///     {
 ///         let mut ts = serializer.serialize_tuple_struct("Rgb", 3)?;
 ///         ts.serialize_field(&self.0)?;
@@ -1577,6 +1721,13 @@ pub trait SerializeTuple {
 ///     }
 /// }
 /// ```
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `SerializeTupleStruct` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait SerializeTupleStruct {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1595,6 +1746,8 @@ pub trait SerializeTupleStruct {
 
 /// Returned from `Serializer::serialize_tuple_variant`.
 ///
+/// # Example use
+///
 /// ```rust
 /// use serde::ser::{Serialize, Serializer, SerializeTupleVariant};
 ///
@@ -1605,7 +1758,8 @@ pub trait SerializeTupleStruct {
 ///
 /// impl Serialize for E {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer
+///     where
+///         S: Serializer,
 ///     {
 ///         match *self {
 ///             E::T(ref a, ref b) => {
@@ -1625,6 +1779,13 @@ pub trait SerializeTupleStruct {
 ///     }
 /// }
 /// ```
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `SerializeTupleVariant` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait SerializeTupleVariant {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1643,6 +1804,8 @@ pub trait SerializeTupleVariant {
 
 /// Returned from `Serializer::serialize_map`.
 ///
+/// # Example use
+///
 /// ```rust
 /// # use std::marker::PhantomData;
 /// #
@@ -1666,11 +1829,13 @@ pub trait SerializeTupleVariant {
 /// use serde::ser::{Serialize, Serializer, SerializeMap};
 ///
 /// impl<K, V> Serialize for HashMap<K, V>
-///     where K: Serialize,
-///           V: Serialize
+/// where
+///     K: Serialize,
+///     V: Serialize,
 /// {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer
+///     where
+///         S: Serializer,
 ///     {
 ///         let mut map = serializer.serialize_map(Some(self.len()))?;
 ///         for (k, v) in self {
@@ -1680,6 +1845,13 @@ pub trait SerializeTupleVariant {
 ///     }
 /// }
 /// ```
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `SerializeMap` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait SerializeMap {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1743,6 +1915,8 @@ pub trait SerializeMap {
 
 /// Returned from `Serializer::serialize_struct`.
 ///
+/// # Example use
+///
 /// ```rust
 /// use serde::ser::{Serialize, Serializer, SerializeStruct};
 ///
@@ -1754,7 +1928,8 @@ pub trait SerializeMap {
 ///
 /// impl Serialize for Rgb {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer
+///     where
+///         S: Serializer,
 ///     {
 ///         let mut rgb = serializer.serialize_struct("Rgb", 3)?;
 ///         rgb.serialize_field("r", &self.r)?;
@@ -1764,6 +1939,13 @@ pub trait SerializeMap {
 ///     }
 /// }
 /// ```
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `SerializeStruct` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait SerializeStruct {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1793,6 +1975,8 @@ pub trait SerializeStruct {
 
 /// Returned from `Serializer::serialize_struct_variant`.
 ///
+/// # Example use
+///
 /// ```rust
 /// use serde::ser::{Serialize, Serializer, SerializeStructVariant};
 ///
@@ -1802,7 +1986,8 @@ pub trait SerializeStruct {
 ///
 /// impl Serialize for E {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer
+///     where
+///         S: Serializer,
 ///     {
 ///         match *self {
 ///             E::S { ref r, ref g, ref b } => {
@@ -1816,6 +2001,13 @@ pub trait SerializeStruct {
 ///     }
 /// }
 /// ```
+///
+/// # Example implementation
+///
+/// The [example data format] presented on the website demonstrates an
+/// implementation of `SerializeStructVariant` for a basic JSON data format.
+///
+/// [example data format]: https://serde.rs/data-format.html
 pub trait SerializeStructVariant {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.45" # remember to update html_root_url
+version = "1.0.66" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -8,8 +8,8 @@ homepage = "https://serde.rs"
 repository = "https://github.com/serde-rs/serde"
 documentation = "https://serde.rs/codegen.html"
 keywords = ["serde", "serialization", "no_std"]
-readme = "README.md"
-include = ["Cargo.toml", "src/**/*.rs", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+readme = "crates-io.md"
+include = ["Cargo.toml", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
 
 [badges]
 travis-ci = { repository = "serde-rs/serde" }
@@ -23,10 +23,9 @@ name = "serde_derive"
 proc-macro = true
 
 [dependencies]
-proc-macro2 = "0.3"
-quote = "0.5.2"
-serde_derive_internals = { version = "=0.23.1", default-features = false, path = "../serde_derive_internals" }
-syn = { version = "0.13", features = ["visit"] }
+proc-macro2 = "0.4"
+quote = "0.6"
+syn = { version = "0.14", features = ["visit"] }
 
 [dev-dependencies]
 serde = { version = "1.0", path = "../serde" }

serde_derive/crates-io.md

@@ -0,0 +1 @@
+../crates-io.md

serde_derive/src/bound.rs

@@ -55,7 +55,8 @@ pub fn with_where_predicates_from_fields(
     generics: &syn::Generics,
     from_field: fn(&attr::Field) -> Option<&[syn::WherePredicate]>,
 ) -> syn::Generics {
-    let predicates = cont.data
+    let predicates = cont
+        .data
         .all_fields()
         .flat_map(|field| from_field(&field.attrs))
         .flat_map(|predicates| predicates.to_vec());
@@ -65,6 +66,28 @@ pub fn with_where_predicates_from_fields(
     generics
 }
 
+pub fn with_where_predicates_from_variants(
+    cont: &Container,
+    generics: &syn::Generics,
+    from_variant: fn(&attr::Variant) -> Option<&[syn::WherePredicate]>,
+) -> syn::Generics {
+    let variants = match cont.data {
+        Data::Enum(ref variants) => variants,
+        Data::Struct(_, _) => {
+            return generics.clone();
+        }
+    };
+
+    let predicates = variants
+        .iter()
+        .flat_map(|variant| from_variant(&variant.attrs))
+        .flat_map(|predicates| predicates.to_vec());
+
+    let mut generics = generics.clone();
+    generics.make_where_clause().predicates.extend(predicates);
+    generics
+}
+
 // Puts the given bound on any generic type parameters that are used in fields
 // for which filter returns true.
 //
@@ -117,9 +140,9 @@ pub fn with_bound(
                 }
             }
             if path.leading_colon.is_none() && path.segments.len() == 1 {
-                let id = path.segments[0].ident;
-                if self.all_type_params.contains(&id) {
-                    self.relevant_type_params.insert(id);
+                let id = &path.segments[0].ident;
+                if self.all_type_params.contains(id) {
+                    self.relevant_type_params.insert(id.clone());
                 }
             }
             visit::visit_path(self, path);
@@ -134,7 +157,10 @@ pub fn with_bound(
         fn visit_macro(&mut self, _mac: &'ast syn::Macro) {}
     }
 
-    let all_type_params = generics.type_params().map(|param| param.ident).collect();
+    let all_type_params = generics
+        .type_params()
+        .map(|param| param.ident.clone())
+        .collect();
 
     let mut visitor = FindTyParams {
         all_type_params: all_type_params,
@@ -162,7 +188,7 @@ pub fn with_bound(
     let associated_type_usage = visitor.associated_type_usage;
     let new_predicates = generics
         .type_params()
-        .map(|param| param.ident)
+        .map(|param| param.ident.clone())
         .filter(|id| relevant_type_params.contains(id))
         .map(|id| syn::TypePath {
             qself: None,
@@ -224,7 +250,7 @@ pub fn with_lifetime_bound(generics: &syn::Generics, lifetime: &str) -> syn::Gen
     let bound = syn::Lifetime::new(lifetime, Span::call_site());
     let def = syn::LifetimeDef {
         attrs: Vec::new(),
-        lifetime: bound,
+        lifetime: bound.clone(),
         colon_token: None,
         bounds: Punctuated::new(),
     };
@@ -234,10 +260,12 @@ pub fn with_lifetime_bound(generics: &syn::Generics, lifetime: &str) -> syn::Gen
         .chain(generics.params.iter().cloned().map(|mut param| {
             match param {
                 syn::GenericParam::Lifetime(ref mut param) => {
-                    param.bounds.push(bound);
+                    param.bounds.push(bound.clone());
                 }
                 syn::GenericParam::Type(ref mut param) => {
-                    param.bounds.push(syn::TypeParamBound::Lifetime(bound));
+                    param
+                        .bounds
+                        .push(syn::TypeParamBound::Lifetime(bound.clone()));
                 }
                 syn::GenericParam::Const(_) => {}
             }
@@ -257,23 +285,24 @@ fn type_of_item(cont: &Container) -> syn::Type {
         path: syn::Path {
             leading_colon: None,
             segments: vec![syn::PathSegment {
-                ident: cont.ident,
+                ident: cont.ident.clone(),
                 arguments: syn::PathArguments::AngleBracketed(
                     syn::AngleBracketedGenericArguments {
                         colon2_token: None,
                         lt_token: Default::default(),
-                        args: cont.generics
+                        args: cont
+                            .generics
                             .params
                             .iter()
                             .map(|param| match *param {
                                 syn::GenericParam::Type(ref param) => {
                                     syn::GenericArgument::Type(syn::Type::Path(syn::TypePath {
                                         qself: None,
-                                        path: param.ident.into(),
+                                        path: param.ident.clone().into(),
                                     }))
                                 }
                                 syn::GenericParam::Lifetime(ref param) => {
-                                    syn::GenericArgument::Lifetime(param.lifetime)
+                                    syn::GenericArgument::Lifetime(param.lifetime.clone())
                                 }
                                 syn::GenericParam::Const(_) => {
                                     panic!("Serde does not support const generics yet");

serde_derive/src/fragment.rs

@@ -6,15 +6,16 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use quote::{ToTokens, Tokens};
+use proc_macro2::TokenStream;
+use quote::ToTokens;
 use syn::token;
 
 pub enum Fragment {
     /// Tokens that can be used as an expression.
-    Expr(Tokens),
+    Expr(TokenStream),
     /// Tokens that can be used inside a block. The surrounding curly braces are
     /// not part of these tokens.
-    Block(Tokens),
+    Block(TokenStream),
 }
 
 macro_rules! quote_expr {
@@ -33,7 +34,7 @@ macro_rules! quote_block {
 /// Block fragments in curly braces.
 pub struct Expr(pub Fragment);
 impl ToTokens for Expr {
-    fn to_tokens(&self, out: &mut Tokens) {
+    fn to_tokens(&self, out: &mut TokenStream) {
         match self.0 {
             Fragment::Expr(ref expr) => expr.to_tokens(out),
             Fragment::Block(ref block) => {
@@ -46,7 +47,7 @@ impl ToTokens for Expr {
 /// Interpolate a fragment as the statements of a block.
 pub struct Stmts(pub Fragment);
 impl ToTokens for Stmts {
-    fn to_tokens(&self, out: &mut Tokens) {
+    fn to_tokens(&self, out: &mut TokenStream) {
         match self.0 {
             Fragment::Expr(ref expr) => expr.to_tokens(out),
             Fragment::Block(ref block) => block.to_tokens(out),
@@ -58,7 +59,7 @@ impl ToTokens for Stmts {
 /// involves putting a comma after expressions and curly braces around blocks.
 pub struct Match(pub Fragment);
 impl ToTokens for Match {
-    fn to_tokens(&self, out: &mut Tokens) {
+    fn to_tokens(&self, out: &mut TokenStream) {
         match self.0 {
             Fragment::Expr(ref expr) => {
                 expr.to_tokens(out);
@@ -71,8 +72,8 @@ impl ToTokens for Match {
     }
 }
 
-impl AsRef<Tokens> for Fragment {
-    fn as_ref(&self) -> &Tokens {
+impl AsRef<TokenStream> for Fragment {
+    fn as_ref(&self) -> &TokenStream {
         match *self {
             Fragment::Expr(ref expr) => expr,
             Fragment::Block(ref block) => block,

serde_derive/src/internals/ast.rs

@@ -6,11 +6,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use attr;
-use check;
+use internals::attr;
+use internals::check;
+use internals::{Ctxt, Derive};
 use syn;
 use syn::punctuated::Punctuated;
-use Ctxt;
 
 pub struct Container<'a> {
     pub ident: syn::Ident,
@@ -32,7 +32,7 @@ pub struct Variant<'a> {
 }
 
 pub struct Field<'a> {
-    pub ident: Option<syn::Ident>,
+    pub member: syn::Member,
     pub attrs: attr::Field,
     pub ty: &'a syn::Type,
     pub original: &'a syn::Field,
@@ -47,7 +47,7 @@ pub enum Style {
 }
 
 impl<'a> Container<'a> {
-    pub fn from_ast(cx: &Ctxt, item: &'a syn::DeriveInput) -> Container<'a> {
+    pub fn from_ast(cx: &Ctxt, item: &'a syn::DeriveInput, derive: Derive) -> Container<'a> {
         let mut attrs = attr::Container::from_ast(cx, item);
 
         let mut data = match item.data {
@@ -86,13 +86,13 @@ impl<'a> Container<'a> {
             attrs.mark_has_flatten();
         }
 
-        let item = Container {
-            ident: item.ident,
+        let mut item = Container {
+            ident: item.ident.clone(),
             attrs: attrs,
             data: data,
             generics: &item.generics,
         };
-        check::check(cx, &item);
+        check::check(cx, &mut item, derive);
         item
     }
 }
@@ -124,7 +124,7 @@ fn enum_from_ast<'a>(
             let (style, fields) =
                 struct_from_ast(cx, &variant.fields, Some(&attrs), container_default);
             Variant {
-                ident: variant.ident,
+                ident: variant.ident.clone(),
                 attrs: attrs,
                 style: style,
                 fields: fields,
@@ -166,7 +166,10 @@ fn fields_from_ast<'a>(
         .iter()
         .enumerate()
         .map(|(i, field)| Field {
-            ident: field.ident,
+            member: match field.ident {
+                Some(ref ident) => syn::Member::Named(ident.clone()),
+                None => syn::Member::Unnamed(i.into()),
+            },
             attrs: attr::Field::from_ast(cx, i, field, attrs, container_default),
             ty: &field.ty,
             original: field,

serde_derive/src/internals/attr.rs

@@ -6,6 +6,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use internals::Ctxt;
 use proc_macro2::{Group, Span, TokenStream, TokenTree};
 use std::collections::BTreeSet;
 use std::str::FromStr;
@@ -15,7 +16,6 @@ use syn::synom::{ParseError, Synom};
 use syn::Ident;
 use syn::Meta::{List, NameValue, Word};
 use syn::NestedMeta::{Literal, Meta};
-use Ctxt;
 
 // This module handles parsing of `#[serde(...)]` attributes. The entrypoints
 // are `attr::Container::from_ast`, `attr::Variant::from_ast`, and
@@ -25,7 +25,7 @@ use Ctxt;
 // user will see errors simultaneously for all bad attributes in the crate
 // rather than just the first.
 
-pub use case::RenameRule;
+pub use internals::case::RenameRule;
 
 #[derive(Copy, Clone)]
 struct Attr<'c, T> {
@@ -105,6 +105,7 @@ impl Name {
 /// Represents container (e.g. struct) attribute information
 pub struct Container {
     name: Name,
+    transparent: bool,
     deny_unknown_fields: bool,
     default: Default,
     rename_all: RenameRule,
@@ -167,6 +168,7 @@ pub enum Identifier {
 }
 
 impl Identifier {
+    #[cfg(feature = "deserialize_in_place")]
     pub fn is_some(self) -> bool {
         match self {
             Identifier::No => false,
@@ -180,6 +182,7 @@ impl Container {
     pub fn from_ast(cx: &Ctxt, item: &syn::DeriveInput) -> Self {
         let mut ser_name = Attr::none(cx, "rename");
         let mut de_name = Attr::none(cx, "rename");
+        let mut transparent = BoolAttr::none(cx, "transparent");
         let mut deny_unknown_fields = BoolAttr::none(cx, "deny_unknown_fields");
         let mut default = Attr::none(cx, "default");
         let mut rename_all = Attr::none(cx, "rename_all");
@@ -199,7 +202,7 @@ impl Container {
                 match meta_item {
                     // Parse `#[serde(rename = "foo")]`
                     Meta(NameValue(ref m)) if m.ident == "rename" => {
-                        if let Ok(s) = get_lit_str(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit) {
+                        if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             ser_name.set(s.value());
                             de_name.set(s.value());
                         }
@@ -215,7 +218,7 @@ impl Container {
 
                     // Parse `#[serde(rename_all = "foo")]`
                     Meta(NameValue(ref m)) if m.ident == "rename_all" => {
-                        if let Ok(s) = get_lit_str(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit) {
+                        if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             match RenameRule::from_str(&s.value()) {
                                 Ok(rename_rule) => rename_all.set(rename_rule),
                                 Err(()) => cx.error(format!(
@@ -227,13 +230,18 @@ impl Container {
                         }
                     }
 
+                    // Parse `#[serde(transparent)]`
+                    Meta(Word(ref word)) if word == "transparent" => {
+                        transparent.set_true();
+                    }
+
                     // Parse `#[serde(deny_unknown_fields)]`
-                    Meta(Word(word)) if word == "deny_unknown_fields" => {
+                    Meta(Word(ref word)) if word == "deny_unknown_fields" => {
                         deny_unknown_fields.set_true();
                     }
 
                     // Parse `#[serde(default)]`
-                    Meta(Word(word)) if word == "default" => match item.data {
+                    Meta(Word(ref word)) if word == "default" => match item.data {
                         syn::Data::Struct(syn::DataStruct {
                             fields: syn::Fields::Named(_),
                             ..
@@ -248,7 +256,7 @@ impl Container {
 
                     // Parse `#[serde(default = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "default" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             match item.data {
                                 syn::Data::Struct(syn::DataStruct {
                                     fields: syn::Fields::Named(_),
@@ -267,7 +275,7 @@ impl Container {
                     // Parse `#[serde(bound = "D: Serialize")]`
                     Meta(NameValue(ref m)) if m.ident == "bound" => {
                         if let Ok(where_predicates) =
-                            parse_lit_into_where(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit)
+                            parse_lit_into_where(cx, &m.ident, &m.ident, &m.lit)
                         {
                             ser_bound.set(where_predicates.clone());
                             de_bound.set(where_predicates);
@@ -283,7 +291,7 @@ impl Container {
                     }
 
                     // Parse `#[serde(untagged)]`
-                    Meta(Word(word)) if word == "untagged" => match item.data {
+                    Meta(Word(ref word)) if word == "untagged" => match item.data {
                         syn::Data::Enum(_) => {
                             untagged.set_true();
                         }
@@ -294,7 +302,7 @@ impl Container {
 
                     // Parse `#[serde(tag = "type")]`
                     Meta(NameValue(ref m)) if m.ident == "tag" => {
-                        if let Ok(s) = get_lit_str(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit) {
+                        if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             match item.data {
                                 syn::Data::Enum(_) => {
                                     internal_tag.set(s.value());
@@ -308,7 +316,7 @@ impl Container {
 
                     // Parse `#[serde(content = "c")]`
                     Meta(NameValue(ref m)) if m.ident == "content" => {
-                        if let Ok(s) = get_lit_str(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit) {
+                        if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             match item.data {
                                 syn::Data::Enum(_) => {
                                     content.set(s.value());
@@ -323,23 +331,23 @@ impl Container {
 
                     // Parse `#[serde(from = "Type")]
                     Meta(NameValue(ref m)) if m.ident == "from" => {
-                        if let Ok(from_ty) = parse_lit_into_ty(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(from_ty) = parse_lit_into_ty(cx, &m.ident, &m.lit) {
                             type_from.set_opt(Some(from_ty));
                         }
                     }
 
                     // Parse `#[serde(into = "Type")]
                     Meta(NameValue(ref m)) if m.ident == "into" => {
-                        if let Ok(into_ty) = parse_lit_into_ty(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(into_ty) = parse_lit_into_ty(cx, &m.ident, &m.lit) {
                             type_into.set_opt(Some(into_ty));
                         }
                     }
 
                     // Parse `#[serde(remote = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "remote" => {
-                        if let Ok(path) = parse_lit_into_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_path(cx, &m.ident, &m.lit) {
                             if is_primitive_path(&path, "Self") {
-                                remote.set(item.ident.into());
+                                remote.set(item.ident.clone().into());
                             } else {
                                 remote.set(path);
                             }
@@ -347,12 +355,12 @@ impl Container {
                     }
 
                     // Parse `#[serde(field_identifier)]`
-                    Meta(Word(word)) if word == "field_identifier" => {
+                    Meta(Word(ref word)) if word == "field_identifier" => {
                         field_identifier.set_true();
                     }
 
                     // Parse `#[serde(variant_identifier)]`
-                    Meta(Word(word)) if word == "variant_identifier" => {
+                    Meta(Word(ref word)) if word == "variant_identifier" => {
                         variant_identifier.set_true();
                     }
 
@@ -375,6 +383,7 @@ impl Container {
                 serialize: ser_name.get().unwrap_or_else(|| item.ident.to_string()),
                 deserialize: de_name.get().unwrap_or_else(|| item.ident.to_string()),
             },
+            transparent: transparent.get(),
             deny_unknown_fields: deny_unknown_fields.get(),
             default: default.get().unwrap_or(Default::None),
             rename_all: rename_all.get().unwrap_or(RenameRule::None),
@@ -397,6 +406,10 @@ impl Container {
         &self.rename_all
     }
 
+    pub fn transparent(&self) -> bool {
+        self.transparent
+    }
+
     pub fn deny_unknown_fields(&self) -> bool {
         self.deny_unknown_fields
     }
@@ -526,6 +539,8 @@ pub struct Variant {
     ser_renamed: bool,
     de_renamed: bool,
     rename_all: RenameRule,
+    ser_bound: Option<Vec<syn::WherePredicate>>,
+    de_bound: Option<Vec<syn::WherePredicate>>,
     skip_deserializing: bool,
     skip_serializing: bool,
     other: bool,
@@ -541,6 +556,8 @@ impl Variant {
         let mut skip_deserializing = BoolAttr::none(cx, "skip_deserializing");
         let mut skip_serializing = BoolAttr::none(cx, "skip_serializing");
         let mut rename_all = Attr::none(cx, "rename_all");
+        let mut ser_bound = Attr::none(cx, "bound");
+        let mut de_bound = Attr::none(cx, "bound");
         let mut other = BoolAttr::none(cx, "other");
         let mut serialize_with = Attr::none(cx, "serialize_with");
         let mut deserialize_with = Attr::none(cx, "deserialize_with");
@@ -551,7 +568,7 @@ impl Variant {
                 match meta_item {
                     // Parse `#[serde(rename = "foo")]`
                     Meta(NameValue(ref m)) if m.ident == "rename" => {
-                        if let Ok(s) = get_lit_str(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit) {
+                        if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             ser_name.set(s.value());
                             de_name.set(s.value());
                         }
@@ -567,7 +584,7 @@ impl Variant {
 
                     // Parse `#[serde(rename_all = "foo")]`
                     Meta(NameValue(ref m)) if m.ident == "rename_all" => {
-                        if let Ok(s) = get_lit_str(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit) {
+                        if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             match RenameRule::from_str(&s.value()) {
                                 Ok(rename_rule) => rename_all.set(rename_rule),
                                 Err(()) => cx.error(format!(
@@ -579,24 +596,48 @@ impl Variant {
                         }
                     }
 
+                    // Parse `#[serde(skip)]`
+                    Meta(Word(ref word)) if word == "skip" => {
+                        skip_serializing.set_true();
+                        skip_deserializing.set_true();
+                    }
+
                     // Parse `#[serde(skip_deserializing)]`
-                    Meta(Word(word)) if word == "skip_deserializing" => {
+                    Meta(Word(ref word)) if word == "skip_deserializing" => {
                         skip_deserializing.set_true();
                     }
 
                     // Parse `#[serde(skip_serializing)]`
-                    Meta(Word(word)) if word == "skip_serializing" => {
+                    Meta(Word(ref word)) if word == "skip_serializing" => {
                         skip_serializing.set_true();
                     }
 
                     // Parse `#[serde(other)]`
-                    Meta(Word(word)) if word == "other" => {
+                    Meta(Word(ref word)) if word == "other" => {
                         other.set_true();
                     }
 
+                    // Parse `#[serde(bound = "D: Serialize")]`
+                    Meta(NameValue(ref m)) if m.ident == "bound" => {
+                        if let Ok(where_predicates) =
+                            parse_lit_into_where(cx, &m.ident, &m.ident, &m.lit)
+                        {
+                            ser_bound.set(where_predicates.clone());
+                            de_bound.set(where_predicates);
+                        }
+                    }
+
+                    // Parse `#[serde(bound(serialize = "D: Serialize", deserialize = "D: Deserialize"))]`
+                    Meta(List(ref m)) if m.ident == "bound" => {
+                        if let Ok((ser, de)) = get_where_predicates(cx, &m.nested) {
+                            ser_bound.set_opt(ser);
+                            de_bound.set_opt(de);
+                        }
+                    }
+
                     // Parse `#[serde(with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "with" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             let mut ser_path = path.clone();
                             ser_path
                                 .path
@@ -614,14 +655,14 @@ impl Variant {
 
                     // Parse `#[serde(serialize_with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "serialize_with" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             serialize_with.set(path);
                         }
                     }
 
                     // Parse `#[serde(deserialize_with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "deserialize_with" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             deserialize_with.set(path);
                         }
                     }
@@ -662,6 +703,8 @@ impl Variant {
             ser_renamed: ser_renamed,
             de_renamed: de_renamed,
             rename_all: rename_all.get().unwrap_or(RenameRule::None),
+            ser_bound: ser_bound.get(),
+            de_bound: de_bound.get(),
             skip_deserializing: skip_deserializing.get(),
             skip_serializing: skip_serializing.get(),
             other: other.get(),
@@ -688,6 +731,14 @@ impl Variant {
         &self.rename_all
     }
 
+    pub fn ser_bound(&self) -> Option<&[syn::WherePredicate]> {
+        self.ser_bound.as_ref().map(|vec| &vec[..])
+    }
+
+    pub fn de_bound(&self) -> Option<&[syn::WherePredicate]> {
+        self.de_bound.as_ref().map(|vec| &vec[..])
+    }
+
     pub fn skip_deserializing(&self) -> bool {
         self.skip_deserializing
     }
@@ -725,6 +776,7 @@ pub struct Field {
     borrowed_lifetimes: BTreeSet<syn::Lifetime>,
     getter: Option<syn::ExprPath>,
     flatten: bool,
+    transparent: bool,
 }
 
 /// Represents the default to use for a field when deserializing.
@@ -737,6 +789,15 @@ pub enum Default {
     Path(syn::ExprPath),
 }
 
+impl Default {
+    pub fn is_none(&self) -> bool {
+        match *self {
+            Default::None => true,
+            Default::Default | Default::Path(_) => false,
+        }
+    }
+}
+
 impl Field {
     /// Extract out the `#[serde(...)]` attributes from a struct field.
     pub fn from_ast(
@@ -766,9 +827,7 @@ impl Field {
         };
 
         let variant_borrow = attrs
-            .map(|variant| &variant.borrow)
-            .unwrap_or(&None)
-            .as_ref()
+            .and_then(|variant| variant.borrow.as_ref())
             .map(|borrow| vec![Meta(borrow.clone())]);
 
         for meta_items in field
@@ -781,7 +840,7 @@ impl Field {
                 match meta_item {
                     // Parse `#[serde(rename = "foo")]`
                     Meta(NameValue(ref m)) if m.ident == "rename" => {
-                        if let Ok(s) = get_lit_str(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit) {
+                        if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             ser_name.set(s.value());
                             de_name.set(s.value());
                         }
@@ -796,57 +855,57 @@ impl Field {
                     }
 
                     // Parse `#[serde(default)]`
-                    Meta(Word(word)) if word == "default" => {
+                    Meta(Word(ref word)) if word == "default" => {
                         default.set(Default::Default);
                     }
 
                     // Parse `#[serde(default = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "default" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             default.set(Default::Path(path));
                         }
                     }
 
                     // Parse `#[serde(skip_serializing)]`
-                    Meta(Word(word)) if word == "skip_serializing" => {
+                    Meta(Word(ref word)) if word == "skip_serializing" => {
                         skip_serializing.set_true();
                     }
 
                     // Parse `#[serde(skip_deserializing)]`
-                    Meta(Word(word)) if word == "skip_deserializing" => {
+                    Meta(Word(ref word)) if word == "skip_deserializing" => {
                         skip_deserializing.set_true();
                     }
 
                     // Parse `#[serde(skip)]`
-                    Meta(Word(word)) if word == "skip" => {
+                    Meta(Word(ref word)) if word == "skip" => {
                         skip_serializing.set_true();
                         skip_deserializing.set_true();
                     }
 
                     // Parse `#[serde(skip_serializing_if = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "skip_serializing_if" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             skip_serializing_if.set(path);
                         }
                     }
 
                     // Parse `#[serde(serialize_with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "serialize_with" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             serialize_with.set(path);
                         }
                     }
 
                     // Parse `#[serde(deserialize_with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "deserialize_with" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             deserialize_with.set(path);
                         }
                     }
 
                     // Parse `#[serde(with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "with" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             let mut ser_path = path.clone();
                             ser_path
                                 .path
@@ -865,7 +924,7 @@ impl Field {
                     // Parse `#[serde(bound = "D: Serialize")]`
                     Meta(NameValue(ref m)) if m.ident == "bound" => {
                         if let Ok(where_predicates) =
-                            parse_lit_into_where(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit)
+                            parse_lit_into_where(cx, &m.ident, &m.ident, &m.lit)
                         {
                             ser_bound.set(where_predicates.clone());
                             de_bound.set(where_predicates);
@@ -881,7 +940,7 @@ impl Field {
                     }
 
                     // Parse `#[serde(borrow)]`
-                    Meta(Word(word)) if word == "borrow" => {
+                    Meta(Word(ref word)) if word == "borrow" => {
                         if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, &field.ty) {
                             borrowed_lifetimes.set(borrowable);
                         }
@@ -889,9 +948,7 @@ impl Field {
 
                     // Parse `#[serde(borrow = "'a + 'b")]`
                     Meta(NameValue(ref m)) if m.ident == "borrow" => {
-                        if let Ok(lifetimes) =
-                            parse_lit_into_lifetimes(cx, m.ident.as_ref(), &m.lit)
-                        {
+                        if let Ok(lifetimes) = parse_lit_into_lifetimes(cx, &m.ident, &m.lit) {
                             if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, &field.ty) {
                                 for lifetime in &lifetimes {
                                     if !borrowable.contains(lifetime) {
@@ -908,13 +965,13 @@ impl Field {
 
                     // Parse `#[serde(getter = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "getter" => {
-                        if let Ok(path) = parse_lit_into_expr_path(cx, m.ident.as_ref(), &m.lit) {
+                        if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             getter.set(path);
                         }
                     }
 
                     // Parse `#[serde(flatten)]`
-                    Meta(Word(word)) if word == "flatten" => {
+                    Meta(Word(ref word)) if word == "flatten" => {
                         flatten.set_true();
                     }
 
@@ -991,7 +1048,7 @@ impl Field {
                 };
                 deserialize_with.set_if_none(expr);
             }
-        } else if is_rptr(&field.ty, is_str) || is_rptr(&field.ty, is_slice_u8) {
+        } else if is_implicitly_borrowed(&field.ty) {
             // Types &str and &[u8] are always implicitly borrowed. No need for
             // a #[serde(borrow)].
             collect_lifetimes(&field.ty, &mut borrowed_lifetimes);
@@ -1019,6 +1076,7 @@ impl Field {
             borrowed_lifetimes: borrowed_lifetimes,
             getter: getter.get(),
             flatten: flatten.get(),
+            transparent: false,
         }
     }
 
@@ -1078,6 +1136,14 @@ impl Field {
     pub fn flatten(&self) -> bool {
         self.flatten
     }
+
+    pub fn transparent(&self) -> bool {
+        self.transparent
+    }
+
+    pub fn mark_transparent(&mut self) {
+        self.transparent = true;
+    }
 }
 
 type SerAndDe<T> = (Option<T>, Option<T>);
@@ -1090,21 +1156,22 @@ fn get_ser_and_de<'a, T, F>(
 ) -> Result<SerAndDe<T>, ()>
 where
     T: 'a,
-    F: Fn(&Ctxt, &str, &str, &'a syn::Lit) -> Result<T, ()>,
+    F: Fn(&Ctxt, &Ident, &Ident, &'a syn::Lit) -> Result<T, ()>,
 {
     let mut ser_meta = Attr::none(cx, attr_name);
     let mut de_meta = Attr::none(cx, attr_name);
+    let attr_name = Ident::new(attr_name, Span::call_site());
 
     for meta in metas {
         match *meta {
             Meta(NameValue(ref meta)) if meta.ident == "serialize" => {
-                if let Ok(v) = f(cx, attr_name, meta.ident.as_ref(), &meta.lit) {
+                if let Ok(v) = f(cx, &attr_name, &meta.ident, &meta.lit) {
                     ser_meta.set(v);
                 }
             }
 
             Meta(NameValue(ref meta)) if meta.ident == "deserialize" => {
-                if let Ok(v) = f(cx, attr_name, meta.ident.as_ref(), &meta.lit) {
+                if let Ok(v) = f(cx, &attr_name, &meta.ident, &meta.lit) {
                     de_meta.set(v);
                 }
             }
@@ -1153,8 +1220,8 @@ pub fn get_serde_meta_items(attr: &syn::Attribute) -> Option<Vec<syn::NestedMeta
 
 fn get_lit_str<'a>(
     cx: &Ctxt,
-    attr_name: &str,
-    meta_item_name: &str,
+    attr_name: &Ident,
+    meta_item_name: &Ident,
     lit: &'a syn::Lit,
 ) -> Result<&'a syn::LitStr, ()> {
     if let syn::Lit::Str(ref lit) = *lit {
@@ -1168,7 +1235,7 @@ fn get_lit_str<'a>(
     }
 }
 
-fn parse_lit_into_path(cx: &Ctxt, attr_name: &str, lit: &syn::Lit) -> Result<syn::Path, ()> {
+fn parse_lit_into_path(cx: &Ctxt, attr_name: &Ident, lit: &syn::Lit) -> Result<syn::Path, ()> {
     let string = try!(get_lit_str(cx, attr_name, attr_name, lit));
     parse_lit_str(string)
         .map_err(|_| cx.error(format!("failed to parse path: {:?}", string.value())))
@@ -1176,7 +1243,7 @@ fn parse_lit_into_path(cx: &Ctxt, attr_name: &str, lit: &syn::Lit) -> Result<syn
 
 fn parse_lit_into_expr_path(
     cx: &Ctxt,
-    attr_name: &str,
+    attr_name: &Ident,
     lit: &syn::Lit,
 ) -> Result<syn::ExprPath, ()> {
     let string = try!(get_lit_str(cx, attr_name, attr_name, lit));
@@ -1186,8 +1253,8 @@ fn parse_lit_into_expr_path(
 
 fn parse_lit_into_where(
     cx: &Ctxt,
-    attr_name: &str,
-    meta_item_name: &str,
+    attr_name: &Ident,
+    meta_item_name: &Ident,
     lit: &syn::Lit,
 ) -> Result<Vec<syn::WherePredicate>, ()> {
     let string = try!(get_lit_str(cx, attr_name, meta_item_name, lit));
@@ -1202,7 +1269,7 @@ fn parse_lit_into_where(
         .map_err(|err| cx.error(err))
 }
 
-fn parse_lit_into_ty(cx: &Ctxt, attr_name: &str, lit: &syn::Lit) -> Result<syn::Type, ()> {
+fn parse_lit_into_ty(cx: &Ctxt, attr_name: &Ident, lit: &syn::Lit) -> Result<syn::Type, ()> {
     let string = try!(get_lit_str(cx, attr_name, attr_name, lit));
 
     parse_lit_str(string).map_err(|_| {
@@ -1218,7 +1285,7 @@ fn parse_lit_into_ty(cx: &Ctxt, attr_name: &str, lit: &syn::Lit) -> Result<syn::
 // lifetimes separated by `+`.
 fn parse_lit_into_lifetimes(
     cx: &Ctxt,
-    attr_name: &str,
+    attr_name: &Ident,
     lit: &syn::Lit,
 ) -> Result<BTreeSet<syn::Lifetime>, ()> {
     let string = try!(get_lit_str(cx, attr_name, attr_name, lit));
@@ -1239,7 +1306,7 @@ fn parse_lit_into_lifetimes(
     if let Ok(BorrowedLifetimes(lifetimes)) = parse_lit_str(string) {
         let mut set = BTreeSet::new();
         for lifetime in lifetimes {
-            if !set.insert(lifetime) {
+            if !set.insert(lifetime.clone()) {
                 cx.error(format!("duplicate borrowed lifetime `{}`", lifetime));
             }
         }
@@ -1253,6 +1320,14 @@ fn parse_lit_into_lifetimes(
     Err(())
 }
 
+fn is_implicitly_borrowed(ty: &syn::Type) -> bool {
+    is_implicitly_borrowed_reference(ty) || is_option(ty, is_implicitly_borrowed_reference)
+}
+
+fn is_implicitly_borrowed_reference(ty: &syn::Type) -> bool {
+    is_reference(ty, is_str) || is_reference(ty, is_slice_u8)
+}
+
 // Whether the type looks like it might be `std::borrow::Cow<T>` where elem="T".
 // This can have false negatives and false positives.
 //
@@ -1300,6 +1375,31 @@ fn is_cow(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
     }
 }
 
+fn is_option(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
+    let path = match *ty {
+        syn::Type::Path(ref ty) => &ty.path,
+        _ => {
+            return false;
+        }
+    };
+    let seg = match path.segments.last() {
+        Some(seg) => seg.into_value(),
+        None => {
+            return false;
+        }
+    };
+    let args = match seg.arguments {
+        syn::PathArguments::AngleBracketed(ref bracketed) => &bracketed.args,
+        _ => {
+            return false;
+        }
+    };
+    seg.ident == "Option" && args.len() == 1 && match args[0] {
+        syn::GenericArgument::Type(ref arg) => elem(arg),
+        _ => false,
+    }
+}
+
 // Whether the type looks like it might be `&T` where elem="T". This can have
 // false negatives and false positives.
 //
@@ -1320,7 +1420,7 @@ fn is_cow(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
 //     struct S<'a> {
 //         r: &'a str,
 //     }
-fn is_rptr(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
+fn is_reference(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
     match *ty {
         syn::Type::Reference(ref ty) => ty.mutability.is_none() && elem(&ty.elem),
         _ => false,
@@ -1346,7 +1446,9 @@ fn is_primitive_type(ty: &syn::Type, primitive: &str) -> bool {
 }
 
 fn is_primitive_path(path: &syn::Path, primitive: &str) -> bool {
-    path.leading_colon.is_none() && path.segments.len() == 1 && path.segments[0].ident == primitive
+    path.leading_colon.is_none()
+        && path.segments.len() == 1
+        && path.segments[0].ident == primitive
         && path.segments[0].arguments.is_empty()
 }
 

serde_derive/src/internals/check.rs

@@ -6,19 +6,21 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use ast::{Container, Data, Style};
-use attr::{EnumTag, Identifier};
-use Ctxt;
+use internals::ast::{Container, Data, Field, Style};
+use internals::attr::{EnumTag, Identifier};
+use internals::{Ctxt, Derive};
+use syn::{Member, Type};
 
 /// Cross-cutting checks that require looking at more than a single attrs
 /// object. Simpler checks should happen when parsing and building the attrs.
-pub fn check(cx: &Ctxt, cont: &Container) {
+pub fn check(cx: &Ctxt, cont: &mut Container, derive: Derive) {
     check_getter(cx, cont);
     check_flatten(cx, cont);
     check_identifier(cx, cont);
     check_variant_skip_attrs(cx, cont);
     check_internal_tag_field_name_conflict(cx, cont);
     check_adjacent_tag_conflict(cx, cont);
+    check_transparent(cx, cont, derive);
 }
 
 /// Getters are only allowed inside structs (not enums) with the `remote`
@@ -44,43 +46,49 @@ fn check_getter(cx: &Ctxt, cont: &Container) {
 /// Flattening has some restrictions we can test.
 fn check_flatten(cx: &Ctxt, cont: &Container) {
     match cont.data {
-        Data::Enum(_) => {
-            if cont.attrs.has_flatten() {
-                cx.error("#[serde(flatten)] cannot be used within enums");
-            }
-        }
-        Data::Struct(style, _) => {
-            for field in cont.data.all_fields() {
-                if !field.attrs.flatten() {
-                    continue;
-                }
-                match style {
-                    Style::Tuple => {
-                        cx.error("#[serde(flatten)] cannot be used on tuple structs");
-                    }
-                    Style::Newtype => {
-                        cx.error("#[serde(flatten)] cannot be used on newtype structs");
-                    }
-                    _ => {}
-                }
-                if field.attrs.skip_serializing() {
-                    cx.error(
-                        "#[serde(flatten] can not be combined with \
-                         #[serde(skip_serializing)]",
-                    );
-                } else if field.attrs.skip_serializing_if().is_some() {
-                    cx.error(
-                        "#[serde(flatten] can not be combined with \
-                         #[serde(skip_serializing_if = \"...\")]",
-                    );
-                } else if field.attrs.skip_deserializing() {
-                    cx.error(
-                        "#[serde(flatten] can not be combined with \
-                         #[serde(skip_deserializing)]",
-                    );
+        Data::Enum(ref variants) => {
+            for variant in variants {
+                for field in &variant.fields {
+                    check_flatten_field(cx, variant.style, field);
                 }
             }
         }
+        Data::Struct(style, ref fields) => {
+            for field in fields {
+                check_flatten_field(cx, style, field);
+            }
+        }
+    }
+}
+
+fn check_flatten_field(cx: &Ctxt, style: Style, field: &Field) {
+    if !field.attrs.flatten() {
+        return;
+    }
+    match style {
+        Style::Tuple => {
+            cx.error("#[serde(flatten)] cannot be used on tuple structs");
+        }
+        Style::Newtype => {
+            cx.error("#[serde(flatten)] cannot be used on newtype structs");
+        }
+        _ => {}
+    }
+    if field.attrs.skip_serializing() {
+        cx.error(
+            "#[serde(flatten] can not be combined with \
+             #[serde(skip_serializing)]",
+        );
+    } else if field.attrs.skip_serializing_if().is_some() {
+        cx.error(
+            "#[serde(flatten] can not be combined with \
+             #[serde(skip_serializing_if = \"...\")]",
+        );
+    } else if field.attrs.skip_deserializing() {
+        cx.error(
+            "#[serde(flatten] can not be combined with \
+             #[serde(skip_deserializing)]",
+        );
     }
 }
 
@@ -165,17 +173,14 @@ fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) {
                 ));
             }
 
-            for (i, field) in variant.fields.iter().enumerate() {
-                let ident = field
-                    .ident
-                    .as_ref()
-                    .map_or_else(|| format!("{}", i), |ident| format!("`{}`", ident));
+            for field in &variant.fields {
+                let member = member_message(&field.member);
 
                 if field.attrs.skip_serializing() {
                     cx.error(format!(
                         "variant `{}` cannot have both #[serde(serialize_with)] and \
                          a field {} marked with #[serde(skip_serializing)]",
-                        variant.ident, ident
+                        variant.ident, member
                     ));
                 }
 
@@ -183,7 +188,7 @@ fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) {
                     cx.error(format!(
                         "variant `{}` cannot have both #[serde(serialize_with)] and \
                          a field {} marked with #[serde(skip_serializing_if)]",
-                        variant.ident, ident
+                        variant.ident, member
                     ));
                 }
             }
@@ -198,17 +203,14 @@ fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) {
                 ));
             }
 
-            for (i, field) in variant.fields.iter().enumerate() {
+            for field in &variant.fields {
                 if field.attrs.skip_deserializing() {
-                    let ident = field
-                        .ident
-                        .as_ref()
-                        .map_or_else(|| format!("{}", i), |ident| format!("`{}`", ident));
+                    let member = member_message(&field.member);
 
                     cx.error(format!(
                         "variant `{}` cannot have both #[serde(deserialize_with)] \
                          and a field {} marked with #[serde(skip_deserializing)]",
-                        variant.ident, ident
+                        variant.ident, member
                     ));
                 }
             }
@@ -276,3 +278,78 @@ fn check_adjacent_tag_conflict(cx: &Ctxt, cont: &Container) {
         cx.error(message);
     }
 }
+
+/// Enums and unit structs cannot be transparent.
+fn check_transparent(cx: &Ctxt, cont: &mut Container, derive: Derive) {
+    if !cont.attrs.transparent() {
+        return;
+    }
+
+    if cont.attrs.type_from().is_some() {
+        cx.error("#[serde(transparent)] is not allowed with #[serde(from = \"...\")]");
+    }
+
+    if cont.attrs.type_into().is_some() {
+        cx.error("#[serde(transparent)] is not allowed with #[serde(into = \"...\")]");
+    }
+
+    let fields = match cont.data {
+        Data::Enum(_) => {
+            cx.error("#[serde(transparent)] is not allowed on an enum");
+            return;
+        }
+        Data::Struct(Style::Unit, _) => {
+            cx.error("#[serde(transparent)] is not allowed on a unit struct");
+            return;
+        }
+        Data::Struct(_, ref mut fields) => fields,
+    };
+
+    let mut transparent_field = None;
+
+    for field in fields {
+        if allow_transparent(field, derive) {
+            if transparent_field.is_some() {
+                cx.error(
+                    "#[serde(transparent)] requires struct to have at most one transparent field",
+                );
+                return;
+            }
+            transparent_field = Some(field);
+        }
+    }
+
+    match transparent_field {
+        Some(transparent_field) => transparent_field.attrs.mark_transparent(),
+        None => match derive {
+            Derive::Serialize => {
+                cx.error("#[serde(transparent)] requires at least one field that is not skipped");
+            }
+            Derive::Deserialize => {
+                cx.error("#[serde(transparent)] requires at least one field that is neither skipped nor has a default");
+            }
+        },
+    }
+}
+
+fn member_message(member: &Member) -> String {
+    match *member {
+        Member::Named(ref ident) => format!("`{}`", ident),
+        Member::Unnamed(ref i) => i.index.to_string(),
+    }
+}
+
+fn allow_transparent(field: &Field, derive: Derive) -> bool {
+    if let Type::Path(ref ty) = *field.ty {
+        if let Some(seg) = ty.path.segments.last() {
+            if seg.into_value().ident == "PhantomData" {
+                return false;
+            }
+        }
+    }
+
+    match derive {
+        Derive::Serialize => !field.attrs.skip_serializing(),
+        Derive::Deserialize => !field.attrs.skip_deserializing() && field.attrs.default().is_none(),
+    }
+}

serde_derive/src/internals/mod.rs

@@ -0,0 +1,22 @@
+// Copyright 2017 Serde Developers
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub mod ast;
+pub mod attr;
+
+mod ctxt;
+pub use self::ctxt::Ctxt;
+
+mod case;
+mod check;
+
+#[derive(Copy, Clone)]
+pub enum Derive {
+    Serialize,
+    Deserialize,
+}

serde_derive/src/lib.rs

@@ -22,10 +22,23 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.45")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.66")]
+#![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
+// Whitelisted clippy lints
 #![cfg_attr(
     feature = "cargo-clippy",
-    allow(enum_variant_names, redundant_field_names, too_many_arguments, used_underscore_binding)
+    allow(
+        enum_variant_names, redundant_field_names, too_many_arguments, used_underscore_binding,
+        cyclomatic_complexity, needless_pass_by_value
+    )
+)]
+// Whitelisted clippy_pedantic lints
+#![cfg_attr(
+    feature = "cargo-clippy",
+    allow(
+        items_after_statements, doc_markdown, stutter, similar_names, use_self, single_match_else,
+        enum_glob_use, match_same_arms, filter_map, cast_possible_truncation
+    )
 )]
 // The `quote!` macro requires deep recursion.
 #![recursion_limit = "512"]
@@ -35,11 +48,11 @@ extern crate quote;
 #[macro_use]
 extern crate syn;
 
-extern crate serde_derive_internals as internals;
-
 extern crate proc_macro;
 extern crate proc_macro2;
 
+mod internals;
+
 use proc_macro::TokenStream;
 use syn::DeriveInput;
 
@@ -56,17 +69,21 @@ mod try;
 #[proc_macro_derive(Serialize, attributes(serde))]
 pub fn derive_serialize(input: TokenStream) -> TokenStream {
     let input: DeriveInput = syn::parse(input).unwrap();
-    match ser::expand_derive_serialize(&input) {
-        Ok(expanded) => expanded.into(),
-        Err(msg) => panic!(msg),
-    }
+    ser::expand_derive_serialize(&input)
+        .unwrap_or_else(compile_error)
+        .into()
 }
 
 #[proc_macro_derive(Deserialize, attributes(serde))]
 pub fn derive_deserialize(input: TokenStream) -> TokenStream {
     let input: DeriveInput = syn::parse(input).unwrap();
-    match de::expand_derive_deserialize(&input) {
-        Ok(expanded) => expanded.into(),
-        Err(msg) => panic!(msg),
+    de::expand_derive_deserialize(&input)
+        .unwrap_or_else(compile_error)
+        .into()
+}
+
+fn compile_error(message: String) -> proc_macro2::TokenStream {
+    quote! {
+        compile_error!(#message);
     }
 }

serde_derive/src/pretend.rs

@@ -1,5 +1,4 @@
-use proc_macro2::Span;
-use quote::Tokens;
+use proc_macro2::{Span, TokenStream};
 use syn::Ident;
 
 use internals::ast::{Container, Data, Field, Style};
@@ -21,7 +20,7 @@ use internals::ast::{Container, Data, Field, Style};
 //     8 | enum EnumDef { V }
 //       |                ^
 //
-pub fn pretend_used(cont: &Container) -> Tokens {
+pub fn pretend_used(cont: &Container) -> TokenStream {
     let pretend_fields = pretend_fields_used(cont);
     let pretend_variants = pretend_variants_used(cont);
 
@@ -49,23 +48,22 @@ pub fn pretend_used(cont: &Container) -> Tokens {
 // The `ref` is important in case the user has written a Drop impl on their
 // type. Rust does not allow destructuring a struct or enum that has a Drop
 // impl.
-fn pretend_fields_used(cont: &Container) -> Tokens {
-    let type_ident = cont.ident;
+fn pretend_fields_used(cont: &Container) -> TokenStream {
+    let type_ident = &cont.ident;
     let (_, ty_generics, _) = cont.generics.split_for_impl();
 
     let patterns = match cont.data {
-        Data::Enum(ref variants) => {
-            variants.iter()
-                .filter_map(|variant| match variant.style {
-                    Style::Struct => {
-                        let variant_ident = variant.ident;
-                        let pat = struct_pattern(&variant.fields);
-                        Some(quote!(#type_ident::#variant_ident #pat))
-                    }
-                    _ => None,
-                })
-                .collect::<Vec<_>>()
-        }
+        Data::Enum(ref variants) => variants
+            .iter()
+            .filter_map(|variant| match variant.style {
+                Style::Struct => {
+                    let variant_ident = &variant.ident;
+                    let pat = struct_pattern(&variant.fields);
+                    Some(quote!(#type_ident::#variant_ident #pat))
+                }
+                _ => None,
+            })
+            .collect::<Vec<_>>(),
         Data::Struct(Style::Struct, ref fields) => {
             let pat = struct_pattern(fields);
             vec![quote!(#type_ident #pat)]
@@ -94,7 +92,7 @@ fn pretend_fields_used(cont: &Container) -> Tokens {
 //         _ => {}
 //     }
 //
-fn pretend_variants_used(cont: &Container) -> Tokens {
+fn pretend_variants_used(cont: &Container) -> TokenStream {
     let variants = match cont.data {
         Data::Enum(ref variants) => variants,
         Data::Struct(_, _) => {
@@ -102,44 +100,41 @@ fn pretend_variants_used(cont: &Container) -> Tokens {
         }
     };
 
-    let type_ident = cont.ident;
+    let type_ident = &cont.ident;
     let (_, ty_generics, _) = cont.generics.split_for_impl();
     let turbofish = ty_generics.as_turbofish();
 
-    let cases = variants.iter()
-        .map(|variant| {
-            let variant_ident = variant.ident;
-            let ref placeholders = (0..variant.fields.len())
-                .map(|i| Ident::new(&format!("__v{}", i), Span::call_site()))
-                .collect::<Vec<_>>();
+    let cases = variants.iter().map(|variant| {
+        let variant_ident = &variant.ident;
+        let placeholders = &(0..variant.fields.len())
+            .map(|i| Ident::new(&format!("__v{}", i), Span::call_site()))
+            .collect::<Vec<_>>();
 
-            let pat = match variant.style {
-                Style::Struct => {
-                    let names = variant.fields.iter().map(|field| field.ident);
-                    quote!({ #(#names: #placeholders),* })
-                }
-                Style::Tuple | Style::Newtype => {
-                    quote!(( #(#placeholders),* ))
-                }
-                Style::Unit => quote!(),
-            };
-
-            quote! {
-                match _serde::export::None {
-                    _serde::export::Some((#(#placeholders,)*)) => {
-                        let _ = #type_ident::#variant_ident #turbofish #pat;
-                    }
-                    _ => {}
-                }
+        let pat = match variant.style {
+            Style::Struct => {
+                let members = variant.fields.iter().map(|field| &field.member);
+                quote!({ #(#members: #placeholders),* })
             }
-        });
+            Style::Tuple | Style::Newtype => quote!(( #(#placeholders),* )),
+            Style::Unit => quote!(),
+        };
+
+        quote! {
+            match _serde::export::None {
+                _serde::export::Some((#(#placeholders,)*)) => {
+                    let _ = #type_ident::#variant_ident #turbofish #pat;
+                }
+                _ => {}
+            }
+        }
+    });
 
     quote!(#(#cases)*)
 }
 
-fn struct_pattern(fields: &[Field]) -> Tokens {
-    let names = fields.iter().map(|field| field.ident);
-    let placeholders = (0..fields.len())
-        .map(|i| Ident::new(&format!("__v{}", i), Span::call_site()));
-    quote!({ #(#names: ref #placeholders),* })
+fn struct_pattern(fields: &[Field]) -> TokenStream {
+    let members = fields.iter().map(|field| &field.member);
+    let placeholders =
+        (0..fields.len()).map(|i| Ident::new(&format!("__v{}", i), Span::call_site()));
+    quote!({ #(#members: ref #placeholders),* })
 }

serde_derive/src/ser.rs

@@ -6,23 +6,20 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use proc_macro2::Span;
-use quote::Tokens;
+use proc_macro2::{Span, TokenStream};
 use syn::spanned::Spanned;
 use syn::{self, Ident, Index, Member};
 
 use bound;
 use fragment::{Fragment, Match, Stmts};
 use internals::ast::{Container, Data, Field, Style, Variant};
-use internals::{attr, Ctxt};
+use internals::{attr, Ctxt, Derive};
 use pretend;
 use try;
 
-use std::u32;
-
-pub fn expand_derive_serialize(input: &syn::DeriveInput) -> Result<Tokens, String> {
+pub fn expand_derive_serialize(input: &syn::DeriveInput) -> Result<TokenStream, String> {
     let ctxt = Ctxt::new();
-    let cont = Container::from_ast(&ctxt, input);
+    let cont = Container::from_ast(&ctxt, input, Derive::Serialize);
     precondition(&ctxt, &cont);
     try!(ctxt.check());
 
@@ -38,7 +35,8 @@ pub fn expand_derive_serialize(input: &syn::DeriveInput) -> Result<Tokens, Strin
         quote! {
             impl #impl_generics #ident #ty_generics #where_clause {
                 #vis fn serialize<__S>(__self: &#remote #ty_generics, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
-                    where __S: _serde::Serializer
+                where
+                    __S: _serde::Serializer,
                 {
                     #used
                     #body
@@ -50,7 +48,8 @@ pub fn expand_derive_serialize(input: &syn::DeriveInput) -> Result<Tokens, Strin
             #[automatically_derived]
             impl #impl_generics _serde::Serialize for #ident #ty_generics #where_clause {
                 fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
-                    where __S: _serde::Serializer
+                where
+                    __S: _serde::Serializer,
                 {
                     #body
                 }
@@ -110,7 +109,7 @@ impl Parameters {
 
         let this = match cont.attrs.remote() {
             Some(remote) => remote.clone(),
-            None => cont.ident.into(),
+            None => cont.ident.clone().into(),
         };
 
         let generics = build_generics(cont);
@@ -125,8 +124,8 @@ impl Parameters {
 
     /// Type name to use in error messages and `&'static str` arguments to
     /// various Serializer methods.
-    fn type_name(&self) -> &str {
-        self.this.segments.last().unwrap().value().ident.as_ref()
+    fn type_name(&self) -> String {
+        self.this.segments.last().unwrap().value().ident.to_string()
     }
 }
 
@@ -138,6 +137,9 @@ fn build_generics(cont: &Container) -> syn::Generics {
     let generics =
         bound::with_where_predicates_from_fields(cont, &generics, attr::Field::ser_bound);
 
+    let generics =
+        bound::with_where_predicates_from_variants(cont, &generics, attr::Variant::ser_bound);
+
     match cont.attrs.ser_bound() {
         Some(predicates) => bound::with_where_predicates(&generics, predicates),
         None => bound::with_bound(
@@ -150,31 +152,31 @@ fn build_generics(cont: &Container) -> syn::Generics {
 }
 
 // Fields with a `skip_serializing` or `serialize_with` attribute, or which
-// belong to a variant with a `serialize_with` attribute, are not serialized by
-// us so we do not generate a bound. Fields with a `bound` attribute specify
-// their own bound so we do not generate one. All other fields may need a `T:
-// Serialize` bound where T is the type of the field.
+// belong to a variant with a 'skip_serializing` or `serialize_with` attribute,
+// are not serialized by us so we do not generate a bound. Fields with a `bound`
+// attribute specify their own bound so we do not generate one. All other fields
+// may need a `T: Serialize` bound where T is the type of the field.
 fn needs_serialize_bound(field: &attr::Field, variant: Option<&attr::Variant>) -> bool {
     !field.skip_serializing() && field.serialize_with().is_none() && field.ser_bound().is_none()
-        && variant.map_or(true, |variant| variant.serialize_with().is_none())
+        && variant.map_or(true, |variant| {
+            !variant.skip_serializing()
+                && variant.serialize_with().is_none()
+                && variant.ser_bound().is_none()
+        })
 }
 
 fn serialize_body(cont: &Container, params: &Parameters) -> Fragment {
-    if let Some(type_into) = cont.attrs.type_into() {
+    if cont.attrs.transparent() {
+        serialize_transparent(cont, params)
+    } else if let Some(type_into) = cont.attrs.type_into() {
         serialize_into(params, type_into)
     } else {
         match cont.data {
             Data::Enum(ref variants) => serialize_enum(params, variants, &cont.attrs),
             Data::Struct(Style::Struct, ref fields) => {
-                if fields.iter().any(|field| field.ident.is_none()) {
-                    panic!("struct has unnamed fields");
-                }
                 serialize_struct(params, fields, &cont.attrs)
             }
             Data::Struct(Style::Tuple, ref fields) => {
-                if fields.iter().any(|field| field.ident.is_some()) {
-                    panic!("tuple struct has named fields");
-                }
                 serialize_tuple_struct(params, fields, &cont.attrs)
             }
             Data::Struct(Style::Newtype, ref fields) => {
@@ -185,6 +187,26 @@ fn serialize_body(cont: &Container, params: &Parameters) -> Fragment {
     }
 }
 
+fn serialize_transparent(cont: &Container, params: &Parameters) -> Fragment {
+    let fields = match cont.data {
+        Data::Struct(_, ref fields) => fields,
+        Data::Enum(_) => unreachable!(),
+    };
+
+    let self_var = &params.self_var;
+    let transparent_field = fields.iter().find(|f| f.attrs.transparent()).unwrap();
+    let member = &transparent_field.member;
+
+    let path = match transparent_field.attrs.serialize_with() {
+        Some(path) => quote!(#path),
+        None => quote!(_serde::Serialize::serialize),
+    };
+
+    quote_block! {
+        #path(&#self_var.#member, __serializer)
+    }
+}
+
 fn serialize_into(params: &Parameters, type_into: &syn::Type) -> Fragment {
     let self_var = &params.self_var;
     quote_block! {
@@ -237,8 +259,28 @@ fn serialize_tuple_struct(
         serialize_tuple_struct_visitor(fields, params, false, &TupleTrait::SerializeTupleStruct);
 
     let type_name = cattrs.name().serialize_name();
-    let len = serialize_stmts.len();
-    let let_mut = mut_if(len > 0);
+
+    let mut serialized_fields = fields
+        .iter()
+        .enumerate()
+        .filter(|&(_, ref field)| !field.attrs.skip_serializing())
+        .peekable();
+
+    let let_mut = mut_if(serialized_fields.peek().is_some());
+
+    let len = serialized_fields
+        .map(|(i, field)| match field.attrs.skip_serializing_if() {
+            None => quote!(1),
+            Some(path) => {
+                let index = syn::Index {
+                    index: i as u32,
+                    span: Span::call_site(),
+                };
+                let field_expr = get_member(params, field, &Member::Unnamed(index));
+                quote!(if #path(#field_expr) { 0 } else { 1 })
+            }
+        })
+        .fold(quote!(0), |sum, expr| quote!(#sum + #expr));
 
     quote_block! {
         let #let_mut __serde_state = try!(_serde::Serializer::serialize_tuple_struct(__serializer, #type_name, #len));
@@ -248,7 +290,7 @@ fn serialize_tuple_struct(
 }
 
 fn serialize_struct(params: &Parameters, fields: &[Field], cattrs: &attr::Container) -> Fragment {
-    assert!(fields.len() as u64 <= u64::from(u32::MAX));
+    assert!(fields.len() as u64 <= u64::from(u32::max_value()));
 
     if cattrs.has_flatten() {
         serialize_struct_as_map(params, fields, cattrs)
@@ -278,8 +320,7 @@ fn serialize_struct_as_struct(
         .map(|field| match field.attrs.skip_serializing_if() {
             None => quote!(1),
             Some(path) => {
-                let ident = field.ident.expect("struct has unnamed fields");
-                let field_expr = get_member(params, field, &Member::Named(ident));
+                let field_expr = get_member(params, field, &field.member);
                 quote!(if #path(#field_expr) { 0 } else { 1 })
             }
         })
@@ -314,8 +355,7 @@ fn serialize_struct_as_map(
             .map(|field| match field.attrs.skip_serializing_if() {
                 None => quote!(1),
                 Some(path) => {
-                    let ident = field.ident.expect("struct has unnamed fields");
-                    let field_expr = get_member(params, field, &Member::Named(ident));
+                    let field_expr = get_member(params, field, &field.member);
                     quote!(if #path(#field_expr) { 0 } else { 1 })
                 }
             })
@@ -331,7 +371,7 @@ fn serialize_struct_as_map(
 }
 
 fn serialize_enum(params: &Parameters, variants: &[Variant], cattrs: &attr::Container) -> Fragment {
-    assert!(variants.len() as u64 <= u64::from(u32::MAX));
+    assert!(variants.len() as u64 <= u64::from(u32::max_value()));
 
     let self_var = &params.self_var;
 
@@ -355,9 +395,9 @@ fn serialize_variant(
     variant: &Variant,
     variant_index: u32,
     cattrs: &attr::Container,
-) -> Tokens {
+) -> TokenStream {
     let this = &params.this;
-    let variant_ident = variant.ident;
+    let variant_ident = &variant.ident;
 
     if variant.attrs.skip_serializing() {
         let skipped_msg = format!(
@@ -397,12 +437,9 @@ fn serialize_variant(
                 }
             }
             Style::Struct => {
-                let fields = variant
-                    .fields
-                    .iter()
-                    .map(|f| f.ident.expect("struct variant has unnamed fields"));
+                let members = variant.fields.iter().map(|f| &f.member);
                 quote! {
-                    #this::#variant_ident { #(ref #fields),* }
+                    #this::#variant_ident { #(ref #members),* }
                 }
             }
         };
@@ -508,7 +545,7 @@ fn serialize_internally_tagged_variant(
     let variant_name = variant.attrs.name().serialize_name();
 
     let enum_ident_str = params.type_name();
-    let variant_ident_str = variant.ident.as_ref();
+    let variant_ident_str = variant.ident.to_string();
 
     if let Some(path) = variant.attrs.serialize_with() {
         let ser = wrap_serialize_variant_with(params, path, variant);
@@ -630,20 +667,16 @@ fn serialize_adjacently_tagged_variant(
                 unreachable!()
             }
         }
-        Style::Newtype => vec![Ident::new("__field0", Span::call_site())],
+        Style::Newtype => vec![Member::Named(Ident::new("__field0", Span::call_site()))],
         Style::Tuple => (0..variant.fields.len())
-            .map(|i| Ident::new(&format!("__field{}", i), Span::call_site()))
-            .collect(),
-        Style::Struct => variant
-            .fields
-            .iter()
-            .map(|f| f.ident.expect("struct variant has unnamed fields"))
+            .map(|i| Member::Named(Ident::new(&format!("__field{}", i), Span::call_site())))
             .collect(),
+        Style::Struct => variant.fields.iter().map(|f| f.member.clone()).collect(),
     };
 
     let (_, ty_generics, where_clause) = params.generics.split_for_impl();
 
-    let wrapper_generics = if let Style::Unit = variant.style {
+    let wrapper_generics = if fields_ident.is_empty() {
         params.generics.clone()
     } else {
         bound::with_lifetime_bound(&params.generics, "'__a")
@@ -658,7 +691,8 @@ fn serialize_adjacently_tagged_variant(
 
         impl #wrapper_impl_generics _serde::Serialize for __AdjacentlyTagged #wrapper_ty_generics #where_clause {
             fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
-                where __S: _serde::Serializer
+            where
+                __S: _serde::Serializer,
             {
                 let (#(#fields_ident,)*) = self.data;
                 #inner
@@ -736,8 +770,23 @@ fn serialize_tuple_variant(
 
     let serialize_stmts = serialize_tuple_struct_visitor(fields, params, true, &tuple_trait);
 
-    let len = serialize_stmts.len();
-    let let_mut = mut_if(len > 0);
+    let mut serialized_fields = fields
+        .iter()
+        .enumerate()
+        .filter(|&(_, ref field)| !field.attrs.skip_serializing())
+        .peekable();
+
+    let let_mut = mut_if(serialized_fields.peek().is_some());
+
+    let len = serialized_fields
+        .map(|(i, field)| match field.attrs.skip_serializing_if() {
+            None => quote!(1),
+            Some(path) => {
+                let field_expr = Ident::new(&format!("__field{}", i), Span::call_site());
+                quote!(if #path(#field_expr) { 0 } else { 1 })
+            }
+        })
+        .fold(quote!(0), |sum, expr| quote!(#sum + #expr));
 
     match context {
         TupleVariant::ExternallyTagged {
@@ -786,6 +835,10 @@ fn serialize_struct_variant<'a>(
     fields: &[Field],
     name: &str,
 ) -> Fragment {
+    if fields.iter().any(|field| field.attrs.flatten()) {
+        return serialize_struct_variant_with_flatten(context, params, fields, name);
+    }
+
     let struct_trait = match context {
         StructVariant::ExternallyTagged { .. } => (StructTrait::SerializeStructVariant),
         StructVariant::InternallyTagged { .. } | StructVariant::Untagged => {
@@ -804,10 +857,10 @@ fn serialize_struct_variant<'a>(
 
     let len = serialized_fields
         .map(|field| {
-            let ident = field.ident.expect("struct has unnamed fields");
+            let member = &field.member;
 
             match field.attrs.skip_serializing_if() {
-                Some(path) => quote!(if #path(#ident) { 0 } else { 1 }),
+                Some(path) => quote!(if #path(#member) { 0 } else { 1 }),
                 None => quote!(1),
             }
         })
@@ -860,15 +913,102 @@ fn serialize_struct_variant<'a>(
     }
 }
 
+fn serialize_struct_variant_with_flatten<'a>(
+    context: StructVariant<'a>,
+    params: &Parameters,
+    fields: &[Field],
+    name: &str,
+) -> Fragment {
+    let struct_trait = StructTrait::SerializeMap;
+    let serialize_fields = serialize_struct_visitor(fields, params, true, &struct_trait);
+
+    let mut serialized_fields = fields
+        .iter()
+        .filter(|&field| !field.attrs.skip_serializing())
+        .peekable();
+
+    let let_mut = mut_if(serialized_fields.peek().is_some());
+
+    match context {
+        StructVariant::ExternallyTagged {
+            variant_index,
+            variant_name,
+        } => {
+            let this = &params.this;
+            let fields_ty = fields.iter().map(|f| &f.ty);
+            let members = &fields.iter().map(|f| &f.member).collect::<Vec<_>>();
+
+            let (_, ty_generics, where_clause) = params.generics.split_for_impl();
+            let wrapper_generics = bound::with_lifetime_bound(&params.generics, "'__a");
+            let (wrapper_impl_generics, wrapper_ty_generics, _) = wrapper_generics.split_for_impl();
+
+            quote_block! {
+                struct __EnumFlatten #wrapper_generics #where_clause {
+                    data: (#(&'__a #fields_ty,)*),
+                    phantom: _serde::export::PhantomData<#this #ty_generics>,
+                }
+
+                impl #wrapper_impl_generics _serde::Serialize for __EnumFlatten #wrapper_ty_generics #where_clause {
+                    fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+                    where
+                        __S: _serde::Serializer,
+                    {
+                        let (#(#members,)*) = self.data;
+                        let #let_mut __serde_state = try!(_serde::Serializer::serialize_map(
+                            __serializer,
+                            _serde::export::None));
+                        #(#serialize_fields)*
+                        _serde::ser::SerializeMap::end(__serde_state)
+                    }
+                }
+
+                _serde::Serializer::serialize_newtype_variant(
+                    __serializer,
+                    #name,
+                    #variant_index,
+                    #variant_name,
+                    &__EnumFlatten {
+                        data: (#(#members,)*),
+                        phantom: _serde::export::PhantomData::<#this #ty_generics>,
+                    })
+            }
+        }
+        StructVariant::InternallyTagged { tag, variant_name } => {
+            quote_block! {
+                let #let_mut __serde_state = try!(_serde::Serializer::serialize_map(
+                    __serializer,
+                    _serde::export::None));
+                try!(_serde::ser::SerializeMap::serialize_entry(
+                    &mut __serde_state,
+                    #tag,
+                    #variant_name,
+                ));
+                #(#serialize_fields)*
+                _serde::ser::SerializeMap::end(__serde_state)
+            }
+        }
+        StructVariant::Untagged => {
+            quote_block! {
+                let #let_mut __serde_state = try!(_serde::Serializer::serialize_map(
+                    __serializer,
+                    _serde::export::None));
+                #(#serialize_fields)*
+                _serde::ser::SerializeMap::end(__serde_state)
+            }
+        }
+    }
+}
+
 fn serialize_tuple_struct_visitor(
     fields: &[Field],
     params: &Parameters,
     is_enum: bool,
     tuple_trait: &TupleTrait,
-) -> Vec<Tokens> {
+) -> Vec<TokenStream> {
     fields
         .iter()
         .enumerate()
+        .filter(|&(_, ref field)| !field.attrs.skip_serializing())
         .map(|(i, field)| {
             let mut field_expr = if is_enum {
                 let id = Ident::new(&format!("__field{}", i), Span::call_site());
@@ -912,17 +1052,17 @@ fn serialize_struct_visitor(
     params: &Parameters,
     is_enum: bool,
     struct_trait: &StructTrait,
-) -> Vec<Tokens> {
+) -> Vec<TokenStream> {
     fields
         .iter()
         .filter(|&field| !field.attrs.skip_serializing())
         .map(|field| {
-            let field_ident = field.ident.expect("struct has unnamed field");
+            let member = &field.member;
 
             let mut field_expr = if is_enum {
-                quote!(#field_ident)
+                quote!(#member)
             } else {
-                get_member(params, field, &Member::Named(field_ident))
+                get_member(params, field, &member)
             };
 
             let key_expr = field.attrs.name().serialize_name();
@@ -976,8 +1116,8 @@ fn wrap_serialize_field_with(
     params: &Parameters,
     field_ty: &syn::Type,
     serialize_with: &syn::ExprPath,
-    field_expr: &Tokens,
-) -> Tokens {
+    field_expr: &TokenStream,
+) -> TokenStream {
     wrap_serialize_with(params, serialize_with, &[field_ty], &[quote!(#field_expr)])
 }
 
@@ -985,16 +1125,18 @@ fn wrap_serialize_variant_with(
     params: &Parameters,
     serialize_with: &syn::ExprPath,
     variant: &Variant,
-) -> Tokens {
+) -> TokenStream {
     let field_tys: Vec<_> = variant.fields.iter().map(|field| field.ty).collect();
     let field_exprs: Vec<_> = variant
         .fields
         .iter()
-        .enumerate()
-        .map(|(i, field)| {
-            let id = field
-                .ident
-                .unwrap_or_else(|| Ident::new(&format!("__field{}", i), Span::call_site()));
+        .map(|field| {
+            let id = match field.member {
+                Member::Named(ref ident) => ident.clone(),
+                Member::Unnamed(ref member) => {
+                    Ident::new(&format!("__field{}", member.index), Span::call_site())
+                }
+            };
             quote!(#id)
         })
         .collect();
@@ -1010,8 +1152,8 @@ fn wrap_serialize_with(
     params: &Parameters,
     serialize_with: &syn::ExprPath,
     field_tys: &[&syn::Type],
-    field_exprs: &[Tokens],
-) -> Tokens {
+    field_exprs: &[TokenStream],
+) -> TokenStream {
     let this = &params.this;
     let (_, ty_generics, where_clause) = params.generics.split_for_impl();
 
@@ -1037,7 +1179,8 @@ fn wrap_serialize_with(
 
         impl #wrapper_impl_generics _serde::Serialize for __SerializeWith #wrapper_ty_generics #where_clause {
             fn serialize<__S>(&self, __s: __S) -> _serde::export::Result<__S::Ok, __S::Error>
-                where __S: _serde::Serializer
+            where
+                __S: _serde::Serializer,
             {
                 #serialize_with(#(self.values.#field_access, )* __s)
             }
@@ -1056,7 +1199,7 @@ fn wrap_serialize_with(
 //     _serde::ser::SerializeStruct::end(__serde_state)
 //
 // where we want to omit the `mut` to avoid a warning.
-fn mut_if(is_mut: bool) -> Option<Tokens> {
+fn mut_if(is_mut: bool) -> Option<TokenStream> {
     if is_mut {
         Some(quote!(mut))
     } else {
@@ -1064,7 +1207,7 @@ fn mut_if(is_mut: bool) -> Option<Tokens> {
     }
 }
 
-fn get_member(params: &Parameters, field: &Field, member: &Member) -> Tokens {
+fn get_member(params: &Parameters, field: &Field, member: &Member) -> TokenStream {
     let self_var = &params.self_var;
     match (params.is_remote, field.attrs.getter()) {
         (false, None) => quote!(&#self_var.#member),
@@ -1090,7 +1233,7 @@ enum StructTrait {
 }
 
 impl StructTrait {
-    fn serialize_field(&self, span: Span) -> Tokens {
+    fn serialize_field(&self, span: Span) -> TokenStream {
         match *self {
             StructTrait::SerializeMap => {
                 quote_spanned!(span=> _serde::ser::SerializeMap::serialize_entry)
@@ -1104,7 +1247,7 @@ impl StructTrait {
         }
     }
 
-    fn skip_field(&self, span: Span) -> Option<Tokens> {
+    fn skip_field(&self, span: Span) -> Option<TokenStream> {
         match *self {
             StructTrait::SerializeMap => None,
             StructTrait::SerializeStruct => {
@@ -1124,7 +1267,7 @@ enum TupleTrait {
 }
 
 impl TupleTrait {
-    fn serialize_element(&self, span: Span) -> Tokens {
+    fn serialize_element(&self, span: Span) -> TokenStream {
         match *self {
             TupleTrait::SerializeTuple => {
                 quote_spanned!(span=> _serde::ser::SerializeTuple::serialize_element)

serde_derive/src/try.rs

@@ -1,13 +1,12 @@
-use proc_macro2::{Op, Spacing};
-use quote::Tokens;
+use proc_macro2::{Punct, Spacing, TokenStream};
 
 // None of our generated code requires the `From::from` error conversion
 // performed by the standard library's `try!` macro. With this simplified macro
 // we see a significant improvement in type checking and borrow checking time of
 // the generated code and a slight improvement in binary size.
-pub fn replacement() -> Tokens {
+pub fn replacement() -> TokenStream {
     // Cannot pass `$expr` to `quote!` prior to Rust 1.17.0 so interpolate it.
-    let dollar = Op::new('$', Spacing::Alone);
+    let dollar = Punct::new('$', Spacing::Alone);
 
     quote! {
         #[allow(unused_macros)]

serde_derive_internals/Cargo.toml

@@ -8,12 +8,15 @@ homepage = "https://serde.rs"
 repository = "https://github.com/serde-rs/serde"
 documentation = "https://docs.serde.rs/serde_derive_internals/"
 keywords = ["serde", "serialization"]
-readme = "README.md"
-include = ["Cargo.toml", "src/**/*.rs", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+readme = "crates-io.md"
+include = ["Cargo.toml", "lib.rs", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+
+[lib]
+path = "lib.rs"
 
 [dependencies]
-proc-macro2 = "0.3"
-syn = { version = "0.13", default-features = false, features = ["derive", "parsing", "clone-impls"] }
+proc-macro2 = "0.4"
+syn = { version = "0.14", default-features = false, features = ["derive", "parsing", "clone-impls"] }
 
 [badges]
 travis-ci = { repository = "serde-rs/serde" }

serde_derive_internals/crates-io.md

@@ -0,0 +1 @@
+../crates-io.md

serde_derive_internals/lib.rs

@@ -17,11 +17,7 @@ extern crate syn;
 
 extern crate proc_macro2;
 
-pub mod ast;
-pub mod attr;
+#[path = "src/mod.rs"]
+mod internals;
 
-mod ctxt;
-pub use ctxt::Ctxt;
-
-mod case;
-mod check;
+pub use internals::*;

serde_derive_internals/src

@@ -0,0 +1 @@
+../serde_derive/src/internals/

serde_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_test"
-version = "1.0.45" # remember to update html_root_url
+version = "1.0.66" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Token De/Serializer for testing De/Serialize implementations"
@@ -8,14 +8,14 @@ homepage = "https://serde.rs"
 repository = "https://github.com/serde-rs/serde"
 documentation = "https://docs.serde.rs/serde_test/"
 keywords = ["serde", "serialization"]
-readme = "README.md"
-include = ["Cargo.toml", "src/**/*.rs", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+readme = "crates-io.md"
+include = ["Cargo.toml", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
 
 [dependencies]
-serde = { version = "1.0.16", path = "../serde" }
+serde = { version = "1.0.60", path = "../serde" }
 
 [dev-dependencies]
-serde = { version = "1.0.16", path = "../serde", features = ["rc"] }
+serde = { version = "1.0", path = "../serde", features = ["rc"] }
 serde_derive = { version = "1.0", path = "../serde_derive" }
 
 [badges]

serde_test/crates-io.md

@@ -0,0 +1 @@
+../crates-io.md

serde_test/src/configure.rs

@@ -1,7 +1,9 @@
 use std::fmt;
 
-use serde::ser::{SerializeMap, SerializeSeq, SerializeStruct, SerializeStructVariant,
-                 SerializeTuple, SerializeTupleStruct, SerializeTupleVariant};
+use serde::ser::{
+    SerializeMap, SerializeSeq, SerializeStruct, SerializeStructVariant, SerializeTuple,
+    SerializeTupleStruct, SerializeTupleVariant,
+};
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
@@ -24,7 +26,8 @@ pub struct Compact<T: ?Sized>(T);
 ///
 /// impl Serialize for Example {
 ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-///         where S: Serializer,
+///     where
+///         S: Serializer,
 ///     {
 ///         if serializer.is_human_readable() {
 ///             format!("{}.{}", self.0, self.1).serialize(serializer)
@@ -36,7 +39,8 @@ pub struct Compact<T: ?Sized>(T);
 ///
 /// impl<'de> Deserialize<'de> for Example {
 ///     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-///         where D: Deserializer<'de>,
+///     where
+///         D: Deserializer<'de>,
 ///     {
 ///         use serde::de::Error;
 ///         if deserializer.is_human_readable() {
@@ -476,7 +480,10 @@ use serde::de::{DeserializeSeed, EnumAccess, Error, MapAccess, SeqAccess, Varian
 macro_rules! forward_deserialize_methods {
     ( $wrapper : ident ( $( $name: ident ),* ) ) => {
         $(
-            fn $name<V>(self, visitor: V) -> Result<V::Value, D::Error> where V: Visitor<'de> {
+            fn $name<V>(self, visitor: V) -> Result<V::Value, D::Error>
+            where
+                V: Visitor<'de>,
+            {
                 (self.0).$name($wrapper(visitor))
             }
         )*

serde_test/src/de.rs

@@ -7,8 +7,10 @@
 // except according to those terms.
 
 use serde::de::value::{MapAccessDeserializer, SeqAccessDeserializer};
-use serde::de::{self, Deserialize, DeserializeSeed, EnumAccess, IntoDeserializer, MapAccess,
-                SeqAccess, VariantAccess, Visitor};
+use serde::de::{
+    self, Deserialize, DeserializeSeed, EnumAccess, IntoDeserializer, MapAccess, SeqAccess,
+    VariantAccess, Visitor,
+};
 
 use error::Error;
 use token::Token;
@@ -127,8 +129,8 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
     type Error = Error;
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf unit seq map identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf unit seq map identifier ignored_any
     }
 
     fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error>
@@ -597,7 +599,8 @@ impl<'de, 'a> MapAccess<'de> for EnumMapVisitor<'a, 'de> {
     {
         match self.variant.take() {
             Some(Token::Str(variant)) => seed.deserialize(variant.into_deserializer()).map(Some),
-            Some(Token::Bytes(variant)) => seed.deserialize(BytesDeserializer { value: variant })
+            Some(Token::Bytes(variant)) => seed
+                .deserialize(BytesDeserializer { value: variant })
                 .map(Some),
             Some(Token::U32(variant)) => seed.deserialize(variant.into_deserializer()).map(Some),
             Some(other) => unexpected!(other),
@@ -654,8 +657,8 @@ impl<'de> de::Deserializer<'de> for BytesDeserializer {
     }
 
     forward_to_deserialize_any! {
-        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
-        byte_buf option unit unit_struct newtype_struct seq tuple tuple_struct
-        map struct enum identifier ignored_any
+        bool i8 i16 i32 i64 i128 u8 u16 u32 u64 u128 f32 f64 char str string
+        bytes byte_buf option unit unit_struct newtype_struct seq tuple
+        tuple_struct map struct enum identifier ignored_any
     }
 }

serde_test/src/lib.rs

@@ -68,11 +68,13 @@
 //! # }
 //! #
 //! # impl<K, V> Serialize for LinkedHashMap<K, V>
-//! #     where K: Serialize,
-//! #           V: Serialize
+//! # where
+//! #     K: Serialize,
+//! #     V: Serialize,
 //! # {
 //! #     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-//! #         where S: Serializer
+//! #     where
+//! #         S: Serializer,
 //! #     {
 //! #         let mut map = serializer.serialize_map(Some(self.0.len()))?;
 //! #         for &(ref k, ref v) in &self.0 {
@@ -85,8 +87,9 @@
 //! # struct LinkedHashMapVisitor<K, V>(PhantomData<(K, V)>);
 //! #
 //! # impl<'de, K, V> Visitor<'de> for LinkedHashMapVisitor<K, V>
-//! #     where K: Deserialize<'de>,
-//! #           V: Deserialize<'de>
+//! # where
+//! #     K: Deserialize<'de>,
+//! #     V: Deserialize<'de>,
 //! # {
 //! #     type Value = LinkedHashMap<K, V>;
 //! #
@@ -95,7 +98,8 @@
 //! #     }
 //! #
 //! #     fn visit_map<M>(self, mut access: M) -> Result<Self::Value, M::Error>
-//! #         where M: MapAccess<'de>
+//! #     where
+//! #         M: MapAccess<'de>,
 //! #     {
 //! #         let mut map = LinkedHashMap::new();
 //! #         while let Some((key, value)) = access.next_entry()? {
@@ -106,11 +110,13 @@
 //! # }
 //! #
 //! # impl<'de, K, V> Deserialize<'de> for LinkedHashMap<K, V>
-//! #     where K: Deserialize<'de>,
-//! #           V: Deserialize<'de>
+//! # where
+//! #     K: Deserialize<'de>,
+//! #     V: Deserialize<'de>,
 //! # {
 //! #     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-//! #         where D: Deserializer<'de>
+//! #     where
+//! #         D: Deserializer<'de>,
 //! #     {
 //! #         deserializer.deserialize_map(LinkedHashMapVisitor(PhantomData))
 //! #     }
@@ -155,7 +161,7 @@
 //! # }
 //! ```
 
-#![doc(html_root_url = "https://docs.rs/serde_test/1.0.45")]
+#![doc(html_root_url = "https://docs.rs/serde_test/1.0.66")]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Whitelisted clippy lints
 #![cfg_attr(feature = "cargo-clippy", allow(float_cmp))]
@@ -179,8 +185,10 @@ mod assert;
 mod configure;
 mod token;
 
-pub use assert::{assert_de_tokens, assert_de_tokens_error, assert_ser_tokens,
-                 assert_ser_tokens_error, assert_tokens};
+pub use assert::{
+    assert_de_tokens, assert_de_tokens_error, assert_ser_tokens, assert_ser_tokens_error,
+    assert_tokens,
+};
 pub use token::Token;
 
 pub use configure::{Compact, Configure, Readable};

test_suite/Cargo.toml

@@ -9,7 +9,7 @@ unstable = ["serde/unstable", "compiletest_rs"]
 
 [dev-dependencies]
 fnv = "1.0"
-proc-macro2 = "0.3"
+proc-macro2 = "0.4"
 rustc-serialize = "0.3.16"
 serde = { path = "../serde", features = ["rc"] }
 serde_derive = { path = "../serde_derive", features = ["deserialize_in_place"] }

test_suite/tests/compile-fail/borrow/bad_lifetimes.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 struct Test<'a> {
-    #[serde(borrow = "zzz")] //~^^ HELP: failed to parse borrowed lifetimes: "zzz"
+    #[serde(borrow = "zzz")]
+    //~^^^ ERROR: failed to parse borrowed lifetimes: "zzz"
     s: &'a str,
 }
 

test_suite/tests/compile-fail/borrow/duplicate_lifetime.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 struct Test<'a> {
-    #[serde(borrow = "'a + 'a")] //~^^ HELP: duplicate borrowed lifetime `'a`
+    #[serde(borrow = "'a + 'a")]
+    //~^^^ ERROR: duplicate borrowed lifetime `'a`
     s: &'a str,
 }
 

test_suite/tests/compile-fail/borrow/duplicate_variant.rs

@@ -12,10 +12,11 @@ extern crate serde_derive;
 #[derive(Deserialize)]
 struct Str<'a>(&'a str);
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 enum Test<'a> {
-    #[serde(borrow)] //~^^ HELP: duplicate serde attribute `borrow`
-    S(#[serde(borrow)] Str<'a>)
+    #[serde(borrow)]
+    //~^^^ ERROR: duplicate serde attribute `borrow`
+    S(#[serde(borrow)] Str<'a>),
 }
 
 fn main() {}

test_suite/tests/compile-fail/borrow/empty_lifetimes.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 struct Test<'a> {
-    #[serde(borrow = "")] //~^^ HELP: at least one lifetime must be borrowed
+    #[serde(borrow = "")]
+    //~^^^ ERROR: at least one lifetime must be borrowed
     s: &'a str,
 }
 

test_suite/tests/compile-fail/borrow/no_lifetimes.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 struct Test {
-    #[serde(borrow)] //~^^ HELP: field `s` has no lifetimes to borrow
+    #[serde(borrow)]
+    //~^^^ ERROR: field `s` has no lifetimes to borrow
     s: String,
 }
 

test_suite/tests/compile-fail/borrow/struct_variant.rs

@@ -12,10 +12,11 @@ extern crate serde_derive;
 #[derive(Deserialize)]
 struct Str<'a>(&'a str);
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 enum Test<'a> {
-    #[serde(borrow)] //~^^ HELP: #[serde(borrow)] may only be used on newtype variants
-    S { s: Str<'a> }
+    #[serde(borrow)]
+    //~^^^ ERROR: #[serde(borrow)] may only be used on newtype variants
+    S { s: Str<'a> },
 }
 
 fn main() {}

test_suite/tests/compile-fail/borrow/wrong_lifetime.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 struct Test<'a> {
-    #[serde(borrow = "'b")] //~^^ HELP: field `s` does not have lifetime 'b
+    #[serde(borrow = "'b")]
+    //~^^^ ERROR: field `s` does not have lifetime 'b
     s: &'a str,
 }
 

test_suite/tests/compile-fail/conflict/adjacent-tag.rs

@@ -9,9 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 #[serde(tag = "conflict", content = "conflict")]
-//~^^ HELP: enum tags `conflict` for type and content conflict with each other
+//~^^ ERROR: enum tags `conflict` for type and content conflict with each other
 enum E {
     A,
     B,

test_suite/tests/compile-fail/conflict/flatten-newtype-struct.rs

@@ -9,8 +9,8 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-//~^ HELP: #[serde(flatten)] cannot be used on newtype structs
+#[derive(Serialize)]
 struct Foo(#[serde(flatten)] HashMap<String, String>);
+//~^^ ERROR: #[serde(flatten)] cannot be used on newtype structs
 
 fn main() {}

test_suite/tests/compile-fail/conflict/flatten-skip-deserializing.rs

@@ -9,16 +9,16 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
-//~^ HELP: #[serde(flatten] can not be combined with #[serde(skip_deserializing)]
+#[derive(Deserialize)]
 struct Foo {
     #[serde(flatten, skip_deserializing)]
+    //~^^^ ERROR: #[serde(flatten] can not be combined with #[serde(skip_deserializing)]
     other: Other,
 }
 
 #[derive(Deserialize)]
 struct Other {
-    x: u32
+    x: u32,
 }
 
 fn main() {}

test_suite/tests/compile-fail/conflict/flatten-skip-serializing-if.rs

@@ -9,16 +9,16 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-//~^ HELP: #[serde(flatten] can not be combined with #[serde(skip_serializing_if = "...")]
+#[derive(Serialize)]
 struct Foo {
-    #[serde(flatten, skip_serializing_if="Option::is_none")]
+    #[serde(flatten, skip_serializing_if = "Option::is_none")]
+    //~^^^ ERROR: #[serde(flatten] can not be combined with #[serde(skip_serializing_if = "...")]
     other: Option<Other>,
 }
 
 #[derive(Serialize)]
 struct Other {
-    x: u32
+    x: u32,
 }
 
 fn main() {}

test_suite/tests/compile-fail/conflict/flatten-skip-serializing.rs

@@ -9,16 +9,16 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-//~^ HELP: #[serde(flatten] can not be combined with #[serde(skip_serializing)]
+#[derive(Serialize)]
 struct Foo {
     #[serde(flatten, skip_serializing)]
+    //~^^^ ERROR: #[serde(flatten] can not be combined with #[serde(skip_serializing)]
     other: Other,
 }
 
 #[derive(Serialize)]
 struct Other {
-    x: u32
+    x: u32,
 }
 
 fn main() {}

test_suite/tests/compile-fail/conflict/flatten-tuple-struct.rs

@@ -9,8 +9,8 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-//~^ HELP: #[serde(flatten)] cannot be used on tuple structs
+#[derive(Serialize)]
 struct Foo(u32, #[serde(flatten)] HashMap<String, String>);
+//~^^ ERROR: #[serde(flatten)] cannot be used on tuple structs
 
 fn main() {}

test_suite/tests/compile-fail/conflict/internal-tag.rs

@@ -9,9 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 #[serde(tag = "conflict")]
-//~^^ HELP: variant field name `conflict` conflicts with internal tag
+//~^^ ERROR: variant field name `conflict` conflicts with internal tag
 enum E {
     A {
         #[serde(rename = "conflict")]

test_suite/tests/compile-fail/default-attribute/enum.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
-#[serde(default)] //~^ HELP: #[serde(default)] can only be used on structs
+#[derive(Deserialize)]
+#[serde(default)]
+//~^^ ERROR: #[serde(default)] can only be used on structs
 enum E {
     S { f: u8 },
 }

test_suite/tests/compile-fail/default-attribute/nameless_struct_fields.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
-#[serde(default)] //~^ HELP: #[serde(default)] can only be used on structs
+#[derive(Deserialize)]
+#[serde(default)]
+//~^^ ERROR: #[serde(default)] can only be used on structs
 struct T(u8, u8);
 
-fn main() { }
+fn main() {}

test_suite/tests/compile-fail/duplicate-attribute/rename-and-ser.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 struct S {
-    #[serde(rename="x", serialize="y")] //~^^ HELP: unknown serde field attribute `serialize`
+    #[serde(rename = "x", serialize = "y")]
+    //~^^^ ERROR: unknown serde field attribute `serialize`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/rename-rename-de.rs

@@ -9,10 +9,11 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 struct S {
-    #[serde(rename="x")]
-    #[serde(rename(deserialize="y"))] //~^^^ HELP: duplicate serde attribute `rename`
+    #[serde(rename = "x")]
+    #[serde(rename(deserialize = "y"))]
+    //~^^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-rename-ser.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 struct S {
-    #[serde(rename(serialize="x"), rename(serialize="y"))] //~^^ HELP: duplicate serde attribute `rename`
+    #[serde(rename(serialize = "x"), rename(serialize = "y"))]
+    //~^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-rename.rs

@@ -9,10 +9,11 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 struct S {
-    #[serde(rename(serialize="x"))]
-    #[serde(rename="y")] //~^^^ HELP: duplicate serde attribute `rename`
+    #[serde(rename(serialize = "x"))]
+    #[serde(rename = "y")]
+    //~^^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-ser.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 struct S {
-    #[serde(rename(serialize="x", serialize="y"))] //~^^ HELP: duplicate serde attribute `rename`
+    #[serde(rename(serialize = "x", serialize = "y"))]
+    //~^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/two-rename-ser.rs

@@ -9,10 +9,11 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 struct S {
-    #[serde(rename(serialize="x"))]
-    #[serde(rename(serialize="y"))] //~^^^ HELP: duplicate serde attribute `rename`
+    #[serde(rename(serialize = "x"))]
+    #[serde(rename(serialize = "y"))]
+    //~^^^^ ERROR: duplicate serde attribute `rename`
     x: (),
 }
 

test_suite/tests/compile-fail/duplicate-attribute/with-and-serialize-with.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 struct S {
-    #[serde(with = "w", serialize_with = "s")] //~^^ HELP: duplicate serde attribute `serialize_with`
+    #[serde(with = "w", serialize_with = "s")]
+    //~^^^ ERROR: duplicate serde attribute `serialize_with`
     x: (),
 }
 

test_suite/tests/compile-fail/enum-representation/internal-tuple-variant.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-#[serde(tag = "type")] //~^ HELP: #[serde(tag = "...")] cannot be used with tuple variants
+#[derive(Serialize)]
+#[serde(tag = "type")]
+//~^^ ERROR: #[serde(tag = "...")] cannot be used with tuple variants
 enum E {
     Tuple(u8, u8),
 }

test_suite/tests/compile-fail/enum-representation/internally-tagged-struct.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-#[serde(tag = "type")] //~^ HELP: #[serde(tag = "...")] can only be used on enums
+#[derive(Serialize)]
+#[serde(tag = "type")]
+//~^^ ERROR: #[serde(tag = "...")] can only be used on enums
 struct S;
 
 fn main() {}

test_suite/tests/compile-fail/enum-representation/untagged-and-internal.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 #[serde(untagged)]
-#[serde(tag = "type")] //~^^ HELP: enum cannot be both untagged and internally tagged
+#[serde(tag = "type")]
+//~^^^ ERROR: enum cannot be both untagged and internally tagged
 enum E {
     A(u8),
     B(String),

test_suite/tests/compile-fail/enum-representation/untagged-struct.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-#[serde(untagged)] //~^ HELP: #[serde(untagged)] can only be used on enums
+#[derive(Serialize)]
+#[serde(untagged)]
+//~^^ ERROR: #[serde(untagged)] can only be used on enums
 struct S;
 
 fn main() {}

test_suite/tests/compile-fail/identifier/both.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
-#[serde(field_identifier, variant_identifier)] //~^ HELP: `field_identifier` and `variant_identifier` cannot both be set
+#[derive(Deserialize)]
+#[serde(field_identifier, variant_identifier)]
+//~^^ ERROR: `field_identifier` and `variant_identifier` cannot both be set
 enum F {
     A,
     B,

test_suite/tests/compile-fail/identifier/field_struct.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 #[serde(field_identifier)]
-struct S; //~^^ HELP: `field_identifier` can only be used on an enum
+//~^^ ERROR: `field_identifier` can only be used on an enum
+struct S;
 
 fn main() {}

test_suite/tests/compile-fail/identifier/field_tuple.rs

@@ -9,11 +9,12 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 #[serde(field_identifier)]
 enum F {
     A,
-    B(u8, u8), //~^^^^ HELP: field_identifier may only contain unit variants
+    B(u8, u8),
+    //~^^^^^ ERROR: field_identifier may only contain unit variants
 }
 
 fn main() {}

test_suite/tests/compile-fail/identifier/newtype_not_last.rs

@@ -9,11 +9,12 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 #[serde(field_identifier)]
 enum F {
     A,
-    Other(String), //~^^^^ HELP: `Other` must be the last variant
+    Other(String),
+    //~^^^^^ ERROR: `Other` must be the last variant
     B,
 }
 

test_suite/tests/compile-fail/identifier/not_identifier.rs

@@ -9,10 +9,11 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 enum F {
     A,
-    #[serde(other)] //~^^^ HELP: #[serde(other)] may only be used inside a field_identifier
+    #[serde(other)]
+    //~^^^^ ERROR: #[serde(other)] may only be used inside a field_identifier
     B,
 }
 

test_suite/tests/compile-fail/identifier/not_unit.rs

@@ -9,11 +9,12 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 #[serde(field_identifier)]
 enum F {
     A,
-    #[serde(other)] //~^^^^ HELP: #[serde(other)] must be on a unit variant
+    #[serde(other)]
+    //~^^^^^ ERROR: #[serde(other)] must be on a unit variant
     Other(u8, u8),
 }
 

test_suite/tests/compile-fail/identifier/other_not_last.rs

@@ -9,11 +9,12 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 #[serde(field_identifier)]
 enum F {
     A,
-    #[serde(other)] //~^^^^ HELP: #[serde(other)] must be the last variant
+    #[serde(other)]
+    //~^^^^^ ERROR: #[serde(other)] must be the last variant
     Other,
     B,
 }

test_suite/tests/compile-fail/identifier/serialize.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-#[serde(field_identifier)] //~^ HELP: field identifiers cannot be serialized
+#[derive(Serialize)]
+#[serde(field_identifier)]
+//~^^ ERROR: field identifiers cannot be serialized
 enum F {
     A,
     B,

test_suite/tests/compile-fail/identifier/variant_struct.rs

@@ -9,8 +9,9 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 #[serde(variant_identifier)]
-struct S; //~^^ HELP: `variant_identifier` can only be used on an enum
+//~^^ ERROR: `variant_identifier` can only be used on an enum
+struct S;
 
 fn main() {}

test_suite/tests/compile-fail/identifier/variant_tuple.rs

@@ -9,11 +9,12 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Deserialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Deserialize)]
 #[serde(variant_identifier)]
 enum F {
     A,
-    B(u8, u8), //~^^^^ HELP: variant_identifier may only contain unit variants
+    B(u8, u8),
+    //~^^^^^ ERROR: variant_identifier may only contain unit variants
 }
 
 fn main() {}

test_suite/tests/compile-fail/precondition/deserialize_de_lifetime.rs

@@ -0,0 +1,16 @@
+// Copyright 2018 Serde Developers
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Deserialize)]
+struct S<'de> {
+    //~^^ ERROR: cannot deserialize when there is a lifetime parameter called 'de
+    s: &'de str,
+}

test_suite/tests/compile-fail/precondition/deserialize_dst.rs

@@ -0,0 +1,17 @@
+// Copyright 2018 Serde Developers
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Deserialize)]
+struct S {
+    string: String,
+    slice: [u8],
+    //~^^^^ ERROR: cannot deserialize a dynamically sized struct
+}

test_suite/tests/compile-fail/remote/bad_getter.rs

@@ -15,10 +15,11 @@ mod remote {
     }
 }
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 #[serde(remote = "remote::S")]
 struct S {
-    #[serde(getter = "~~~")] //~^^^ HELP: failed to parse path: "~~~"
+    #[serde(getter = "~~~")]
+    //~^^^^ ERROR: failed to parse path: "~~~"
     a: u8,
 }
 

test_suite/tests/compile-fail/remote/bad_remote.rs

@@ -15,8 +15,9 @@ mod remote {
     }
 }
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-#[serde(remote = "~~~")] //~^ HELP: failed to parse path: "~~~"
+#[derive(Serialize)]
+#[serde(remote = "~~~")]
+//~^^ ERROR: failed to parse path: "~~~"
 struct S {
     a: u8,
 }

test_suite/tests/compile-fail/remote/enum_getter.rs

@@ -11,17 +11,18 @@ extern crate serde_derive;
 
 mod remote {
     pub enum E {
-        A { a: u8 }
+        A { a: u8 },
     }
 }
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 #[serde(remote = "remote::E")]
 pub enum E {
     A {
-        #[serde(getter = "get_a")] //~^^^^ HELP: #[serde(getter = "...")] is not allowed in an enum
+        #[serde(getter = "get_a")]
+        //~^^^^^ ERROR: #[serde(getter = "...")] is not allowed in an enum
         a: u8,
-    }
+    },
 }
 
 fn main() {}

test_suite/tests/compile-fail/remote/missing_field.rs

@@ -19,7 +19,8 @@ mod remote {
 #[derive(Serialize, Deserialize)]
 #[serde(remote = "remote::S")]
 struct S {
-    a: u8, //~^^^ ERROR: missing field `b` in initializer of `remote::S`
+    a: u8,
+    //~^^^^ ERROR: missing field `b` in initializer of `remote::S`
 }
 
 fn main() {}

test_suite/tests/compile-fail/remote/nonremote_getter.rs

@@ -9,9 +9,10 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
+#[derive(Serialize)]
 struct S {
-    #[serde(getter = "S::get")] //~^^ HELP: #[serde(getter = "...")] can only be used in structs that have #[serde(remote = "...")]
+    #[serde(getter = "S::get")]
+    //~^^^ ERROR: #[serde(getter = "...")] can only be used in structs that have #[serde(remote = "...")]
     a: u8,
 }
 

test_suite/tests/compile-fail/remote/unknown_field.rs

@@ -19,7 +19,8 @@ mod remote {
 #[serde(remote = "remote::S")]
 struct S {
     //~^^^ ERROR: struct `remote::S` has no field named `b`
-    b: u8, //~^^^^ ERROR: no field `b` on type `&remote::S`
+    b: u8,
+    //~^^^^^ ERROR: no field `b` on type `&remote::S`
 }
 
 fn main() {}

test_suite/tests/compile-fail/remote/wrong_de.rs

@@ -13,8 +13,10 @@ mod remote {
     pub struct S(pub u16);
 }
 
-#[derive(Deserialize)] //~ ERROR: mismatched types
+#[derive(Deserialize)]
 #[serde(remote = "remote::S")]
-struct S(u8); //~^^ expected u16, found u8
+struct S(u8);
+//~^^^ ERROR: mismatched types
+//~^^^^ expected u16, found u8
 
 fn main() {}

test_suite/tests/compile-fail/remote/wrong_getter.rs

@@ -21,11 +21,13 @@ mod remote {
     }
 }
 
-#[derive(Serialize)] //~ ERROR: mismatched types
+#[derive(Serialize)]
 #[serde(remote = "remote::S")]
 struct S {
     #[serde(getter = "remote::S::get")]
-    a: u8, //~^^^^ expected u8, found u16
+    //~^^^^ ERROR: mismatched types
+    a: u8,
+    //~^^^^^^ expected u8, found u16
 }
 
 fn main() {}

test_suite/tests/compile-fail/remote/wrong_ser.rs

@@ -15,10 +15,12 @@ mod remote {
     }
 }
 
-#[derive(Serialize)] //~ ERROR: mismatched types
+#[derive(Serialize)]
 #[serde(remote = "remote::S")]
 struct S {
-    a: u8, //~^^^ expected u8, found u16
+    a: u8,
+    //~^^^^ ERROR: mismatched types
+    //~^^^^^ expected u8, found u16
 }
 
 fn main() {}

test_suite/tests/compile-fail/transparent/at_most_one.rs

@@ -9,13 +9,12 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
-//~^ HELP: #[serde(flatten)] cannot be used within enums
-enum Foo {
-    A {
-        #[serde(flatten)]
-        fields: HashMap<String, String>,
-    }
+#[derive(Serialize)]
+#[serde(transparent)]
+//~^^ ERROR: #[serde(transparent)] requires struct to have at most one transparent field
+struct S {
+    a: u8,
+    b: u8,
 }
 
 fn main() {}

test_suite/tests/compile-fail/transparent/de_at_least_one.rs

@@ -0,0 +1,22 @@
+// Copyright 2018 Serde Developers
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Deserialize)]
+#[serde(transparent)]
+//~^^ ERROR: #[serde(transparent)] requires at least one field that is neither skipped nor has a default
+struct S {
+    #[serde(skip)]
+    a: u8,
+    #[serde(default)]
+    b: u8,
+}
+
+fn main() {}

test_suite/tests/compile-fail/transparent/ser_at_least_one.rs

@@ -0,0 +1,20 @@
+// Copyright 2018 Serde Developers
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Serialize)]
+#[serde(transparent)]
+//~^^ ERROR: #[serde(transparent)] requires at least one field that is not skipped
+struct S {
+    #[serde(skip)]
+    a: u8,
+}
+
+fn main() {}