Release 1.0.122

I think there is no ambiguity in from_str as a method name so "choose a
less ambiguous method name" is unnecessary, and it can't be a FromStr
impl in this case because FromStr's error type cannot borrow from the
input string slice.

    warning: method `from_str` can be confused for the standard trait method `std::str::FromStr::from_str`
      --> serde_derive_internals/src/case.rs:50:5
       |
    50 | /     pub fn from_str(rename_all_str: &str) -> Result<Self, ParseError> {
    51 | |         for (name, rule) in RENAME_RULES {
    52 | |             if rename_all_str == *name {
    53 | |                 return Ok(*rule);
    ...  |
    58 | |         })
    59 | |     }
       | |_____^
       |
       = note: `#[warn(clippy::should_implement_trait)]` on by default
       = help: consider implementing the trait `std::str::FromStr` or choosing a less ambiguous method name
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#should_implement_trait

.github/workflows/ci.yml

@@ -158,6 +158,7 @@ jobs:
         # https://github.com/rust-lang/rust-clippy/issues/5356
       - run: cd serde && cargo clippy --features rc,unstable -- -D clippy::all -A clippy::redundant_field_names
       - run: cd serde_derive && cargo clippy -- -D clippy::all
+      - run: cd serde_derive_internals && cargo clippy -- -D clippy::all
       - run: cd serde_test && cargo clippy -- -D clippy::all -A clippy::redundant_field_names
       - run: cd test_suite && cargo clippy --tests --features unstable -- -D clippy::all -A clippy::redundant_field_names
       - run: cd test_suite/no_std && cargo clippy -- -D clippy::all -A clippy::redundant_field_names

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.119" # remember to update html_root_url and serde_derive dependency
+version = "1.0.122" # remember to update html_root_url and serde_derive dependency
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -14,7 +14,7 @@ include = ["build.rs", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APAC
 build = "build.rs"
 
 [dependencies]
-serde_derive = { version = "=1.0.119", optional = true, path = "../serde_derive" }
+serde_derive = { version = "=1.0.122", optional = true, path = "../serde_derive" }
 
 [dev-dependencies]
 serde_derive = { version = "1.0", path = "../serde_derive" }

serde/src/de/ignored_any.rs

@@ -130,12 +130,28 @@ impl<'de> Visitor<'de> for IgnoredAny {
         Ok(IgnoredAny)
     }
 
+    serde_if_integer128! {
+        #[inline]
+        fn visit_i128<E>(self, x: i128) -> Result<Self::Value, E> {
+            let _ = x;
+            Ok(IgnoredAny)
+        }
+    }
+
     #[inline]
     fn visit_u64<E>(self, x: u64) -> Result<Self::Value, E> {
         let _ = x;
         Ok(IgnoredAny)
     }
 
+    serde_if_integer128! {
+        #[inline]
+        fn visit_u128<E>(self, x: u128) -> Result<Self::Value, E> {
+            let _ = x;
+            Ok(IgnoredAny)
+        }
+    }
+
     #[inline]
     fn visit_f64<E>(self, x: f64) -> Result<Self::Value, E> {
         let _ = x;

serde/src/de/impls.rs

@@ -1260,24 +1260,7 @@ macro_rules! parse_ip_impl {
                 D: Deserializer<'de>,
             {
                 if deserializer.is_human_readable() {
-                    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)
+                    deserializer.deserialize_str(FromStrVisitor::new($expecting))
                 } else {
                     <[u8; $size]>::deserialize(deserializer).map(<$ty>::from)
                 }
@@ -1405,24 +1388,7 @@ impl<'de> Deserialize<'de> for net::IpAddr {
         D: Deserializer<'de>,
     {
         if deserializer.is_human_readable() {
-            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)
+            deserializer.deserialize_str(FromStrVisitor::new("IP address"))
         } else {
             use lib::net::IpAddr;
             deserialize_enum! {
@@ -1449,24 +1415,7 @@ macro_rules! parse_socket_impl {
                 D: Deserializer<'de>,
             {
                 if deserializer.is_human_readable() {
-                    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)
+                    deserializer.deserialize_str(FromStrVisitor::new($expecting))
                 } else {
                     <(_, u16)>::deserialize(deserializer).map(|(ip, port)| $new(ip, port))
                 }
@@ -1482,24 +1431,7 @@ impl<'de> Deserialize<'de> for net::SocketAddr {
         D: Deserializer<'de>,
     {
         if deserializer.is_human_readable() {
-            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)
+            deserializer.deserialize_str(FromStrVisitor::new("socket address"))
         } else {
             use lib::net::SocketAddr;
             deserialize_enum! {
@@ -1917,6 +1849,17 @@ impl<'de> Deserialize<'de> for Duration {
             }
         }
 
+        fn check_overflow<E>(secs: u64, nanos: u32) -> Result<(), E>
+        where
+            E: Error,
+        {
+            static NANOS_PER_SEC: u32 = 1_000_000_000;
+            match secs.checked_add((nanos / NANOS_PER_SEC) as u64) {
+                Some(_) => Ok(()),
+                None => Err(E::custom("overflow deserializing Duration")),
+            }
+        }
+
         struct DurationVisitor;
 
         impl<'de> Visitor<'de> for DurationVisitor {
@@ -1942,6 +1885,7 @@ impl<'de> Deserialize<'de> for Duration {
                         return Err(Error::invalid_length(1, &self));
                     }
                 };
+                try!(check_overflow(secs, nanos));
                 Ok(Duration::new(secs, nanos))
             }
 
@@ -1975,6 +1919,7 @@ impl<'de> Deserialize<'de> for Duration {
                     Some(nanos) => nanos,
                     None => return Err(<A::Error as Error>::missing_field("nanos")),
                 };
+                try!(check_overflow(secs, nanos));
                 Ok(Duration::new(secs, nanos))
             }
         }
@@ -2603,3 +2548,39 @@ atomic_impl! {
 atomic_impl! {
     AtomicI64 AtomicU64
 }
+
+#[cfg(feature = "std")]
+struct FromStrVisitor<T> {
+    expecting: &'static str,
+    ty: PhantomData<T>,
+}
+
+#[cfg(feature = "std")]
+impl<T> FromStrVisitor<T> {
+    fn new(expecting: &'static str) -> Self {
+        FromStrVisitor {
+            expecting: expecting,
+            ty: PhantomData,
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl<'de, T> Visitor<'de> for FromStrVisitor<T>
+where
+    T: str::FromStr,
+    T::Err: fmt::Display,
+{
+    type Value = T;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str(self.expecting)
+    }
+
+    fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
+    where
+        E: Error,
+    {
+        s.parse().map_err(Error::custom)
+    }
+}

serde/src/de/mod.rs

@@ -393,7 +393,7 @@ pub enum Unexpected<'a> {
 }
 
 impl<'a> fmt::Display for Unexpected<'a> {
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         use self::Unexpected::*;
         match *self {
             Bool(b) => write!(formatter, "boolean `{}`", b),

serde/src/de/value.rs

@@ -25,7 +25,7 @@ use lib::*;
 
 use self::private::{First, Second};
 use __private::de::size_hint;
-use de::{self, Expected, IntoDeserializer, SeqAccess};
+use de::{self, Deserializer, Expected, IntoDeserializer, SeqAccess, Visitor};
 use ser;
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -48,7 +48,7 @@ macro_rules! impl_copy_clone {
 
 /// A minimal representation of all possible errors that can occur using the
 /// `IntoDeserializer` trait.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, PartialEq)]
 pub struct Error {
     err: ErrorImpl,
 }
@@ -93,16 +93,25 @@ impl ser::Error for Error {
 
 impl Display for Error {
     #[cfg(any(feature = "std", feature = "alloc"))]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter.write_str(&self.err)
     }
 
     #[cfg(not(any(feature = "std", feature = "alloc")))]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter.write_str("Serde deserialization error")
     }
 }
 
+impl Debug for Error {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = formatter.debug_tuple("Error");
+        #[cfg(any(feature = "std", feature = "alloc"))]
+        debug.field(&self.err);
+        debug.finish()
+    }
+}
+
 #[cfg(feature = "std")]
 impl error::Error for Error {
     fn description(&self) -> &str {
@@ -126,7 +135,6 @@ where
 }
 
 /// A deserializer holding a `()`.
-#[derive(Debug)]
 pub struct UnitDeserializer<E> {
     marker: PhantomData<E>,
 }
@@ -160,6 +168,12 @@ where
     }
 }
 
+impl<E> Debug for UnitDeserializer<E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.debug_struct("UnitDeserializer").finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer that cannot be instantiated.
@@ -208,7 +222,6 @@ macro_rules! primitive_deserializer {
     ($ty:ty, $doc:tt, $name:ident, $method:ident $($cast:tt)*) => {
         #[doc = "A deserializer holding"]
         #[doc = $doc]
-        #[derive(Debug)]
         pub struct $name<E> {
             value: $ty,
             marker: PhantomData<E>
@@ -249,6 +262,15 @@ macro_rules! primitive_deserializer {
                 visitor.$method(self.value $($cast)*)
             }
         }
+
+        impl<E> Debug for $name<E> {
+            fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter
+                    .debug_struct(stringify!($name))
+                    .field("value", &self.value)
+                    .finish()
+            }
+        }
     }
 }
 
@@ -272,7 +294,6 @@ serde_if_integer128! {
 }
 
 /// A deserializer holding a `u32`.
-#[derive(Debug)]
 pub struct U32Deserializer<E> {
     value: u32,
     marker: PhantomData<E>,
@@ -343,10 +364,18 @@ where
     }
 }
 
+impl<E> Debug for U32Deserializer<E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("U32Deserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `&str`.
-#[derive(Debug)]
 pub struct StrDeserializer<'a, E> {
     value: &'a str,
     marker: PhantomData<E>,
@@ -417,11 +446,19 @@ where
     }
 }
 
+impl<'a, E> Debug for StrDeserializer<'a, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("StrDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `&str` with a lifetime tied to another
 /// deserializer.
-#[derive(Debug)]
 pub struct BorrowedStrDeserializer<'de, E> {
     value: &'de str,
     marker: PhantomData<E>,
@@ -488,11 +525,19 @@ where
     }
 }
 
+impl<'de, E> Debug for BorrowedStrDeserializer<'de, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("BorrowedStrDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `String`.
 #[cfg(any(feature = "std", feature = "alloc"))]
-#[derive(Debug)]
 pub struct StringDeserializer<E> {
     value: String,
     marker: PhantomData<E>,
@@ -574,11 +619,20 @@ where
     }
 }
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<E> Debug for StringDeserializer<E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("StringDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `Cow<str>`.
 #[cfg(any(feature = "std", feature = "alloc"))]
-#[derive(Debug)]
 pub struct CowStrDeserializer<'a, E> {
     value: Cow<'a, str>,
     marker: PhantomData<E>,
@@ -663,29 +717,48 @@ where
     }
 }
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, E> Debug for CowStrDeserializer<'a, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("CowStrDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
-/// A deserializer holding a `&[u8]` with a lifetime tied to another
-/// deserializer.
-#[derive(Debug)]
-pub struct BorrowedBytesDeserializer<'de, E> {
-    value: &'de [u8],
+/// A deserializer holding a `&[u8]`. Always calls [`Visitor::visit_bytes`].
+pub struct BytesDeserializer<'a, E> {
+    value: &'a [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> {
-        BorrowedBytesDeserializer {
+impl<'a, E> BytesDeserializer<'a, E> {
+    /// Create a new deserializer from the given bytes.
+    pub fn new(value: &'a [u8]) -> Self {
+        BytesDeserializer {
             value: value,
             marker: PhantomData,
         }
     }
 }
 
-impl<'de, E> de::Deserializer<'de> for BorrowedBytesDeserializer<'de, E>
+impl_copy_clone!(BytesDeserializer<'a>);
+
+impl<'de, 'a, E> IntoDeserializer<'de, E> for &'a [u8]
+where
+    E: de::Error,
+{
+    type Deserializer = BytesDeserializer<'a, E>;
+
+    fn into_deserializer(self) -> BytesDeserializer<'a, E> {
+        BytesDeserializer::new(self)
+    }
+}
+
+impl<'de, 'a, E> Deserializer<'de> for BytesDeserializer<'a, E>
 where
     E: de::Error,
 {
@@ -693,7 +766,55 @@ where
 
     fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
     where
-        V: de::Visitor<'de>,
+        V: Visitor<'de>,
+    {
+        visitor.visit_bytes(self.value)
+    }
+
+    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
+    }
+}
+
+impl<'a, E> Debug for BytesDeserializer<'a, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("BytesDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
+/// A deserializer holding a `&[u8]` with a lifetime tied to another
+/// deserializer. Always calls [`Visitor::visit_borrowed_bytes`].
+pub struct BorrowedBytesDeserializer<'de, E> {
+    value: &'de [u8],
+    marker: PhantomData<E>,
+}
+
+impl<'de, E> BorrowedBytesDeserializer<'de, E> {
+    /// Create a new borrowed deserializer from the given borrowed bytes.
+    pub fn new(value: &'de [u8]) -> Self {
+        BorrowedBytesDeserializer {
+            value: value,
+            marker: PhantomData,
+        }
+    }
+}
+
+impl_copy_clone!(BorrowedBytesDeserializer<'de>);
+
+impl<'de, E> Deserializer<'de> for BorrowedBytesDeserializer<'de, E>
+where
+    E: de::Error,
+{
+    type Error = E;
+
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
     {
         visitor.visit_borrowed_bytes(self.value)
     }
@@ -701,14 +822,23 @@ where
     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 identifier ignored_any enum
+        tuple_struct map struct enum identifier ignored_any
+    }
+}
+
+impl<'de, E> Debug for BorrowedBytesDeserializer<'de, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("BorrowedBytesDeserializer")
+            .field("value", &self.value)
+            .finish()
     }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer that iterates over a sequence.
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub struct SeqDeserializer<I, E> {
     iter: iter::Fuse<I>,
     count: usize,
@@ -813,6 +943,19 @@ impl Expected for ExpectedInSeq {
     }
 }
 
+impl<I, E> Debug for SeqDeserializer<I, E>
+where
+    I: Debug,
+{
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("SeqDeserializer")
+            .field("iter", &self.iter)
+            .field("count", &self.count)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 #[cfg(any(feature = "std", feature = "alloc"))]
@@ -1108,7 +1251,6 @@ where
     }
 }
 
-// Cannot #[derive(Debug)] because of the bound `Second<I::Item>: Debug`.
 impl<'de, I, E> Debug for MapDeserializer<'de, I, E>
 where
     I: Iterator + Debug,
@@ -1121,8 +1263,6 @@ where
             .field("iter", &self.iter)
             .field("value", &self.value)
             .field("count", &self.count)
-            .field("lifetime", &self.lifetime)
-            .field("error", &self.error)
             .finish()
     }
 }
@@ -1331,7 +1471,6 @@ mod private {
 
     use de::{self, DeserializeSeed, Deserializer, MapAccess, Unexpected, VariantAccess, Visitor};
 
-    #[derive(Clone, Debug)]
     pub struct UnitOnly<E> {
         marker: PhantomData<E>,
     }
@@ -1390,7 +1529,6 @@ mod private {
         }
     }
 
-    #[derive(Clone, Debug)]
     pub struct MapAsEnum<A> {
         map: A,
     }

serde/src/integer128.rs

@@ -10,7 +10,7 @@
 /// bother with this macro and may assume support for 128-bit integers.
 ///
 /// ```edition2018
-/// # use serde::__private::ser::Error;
+/// # use serde::__private::doc::Error;
 /// #
 /// # struct MySerializer;
 /// #

serde/src/lib.rs

@@ -84,7 +84,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.119")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.122")]
 // 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

serde/src/private/de.rs

@@ -1,5 +1,6 @@
 use lib::*;
 
+use de::value::{BorrowedBytesDeserializer, BytesDeserializer};
 use de::{Deserialize, DeserializeSeed, Deserializer, Error, IntoDeserializer, Visitor};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
@@ -824,15 +825,17 @@ mod content {
     /// Not public API.
     pub struct TaggedContentVisitor<'de, T> {
         tag_name: &'static str,
+        expecting: &'static str,
         value: PhantomData<TaggedContent<'de, T>>,
     }
 
     impl<'de, T> TaggedContentVisitor<'de, T> {
         /// Visitor for the content of an internally tagged enum with the given
         /// tag name.
-        pub fn new(name: &'static str) -> Self {
+        pub fn new(name: &'static str, expecting: &'static str) -> Self {
             TaggedContentVisitor {
                 tag_name: name,
+                expecting: expecting,
                 value: PhantomData,
             }
         }
@@ -861,7 +864,7 @@ mod content {
         type Value = TaggedContent<'de, T>;
 
         fn expecting(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-            fmt.write_str("internally tagged enum")
+            fmt.write_str(self.expecting)
         }
 
         fn visit_seq<S>(self, mut seq: S) -> Result<Self::Value, S::Error>
@@ -2542,11 +2545,13 @@ pub trait IdentifierDeserializer<'de, E: Error> {
     fn from(self) -> Self::Deserializer;
 }
 
-impl<'de, E> IdentifierDeserializer<'de, E> for u32
+pub struct Borrowed<'de, T: 'de + ?Sized>(pub &'de T);
+
+impl<'de, E> IdentifierDeserializer<'de, E> for u64
 where
     E: Error,
 {
-    type Deserializer = <u32 as IntoDeserializer<'de, E>>::Deserializer;
+    type Deserializer = <u64 as IntoDeserializer<'de, E>>::Deserializer;
 
     fn from(self) -> Self::Deserializer {
         self.into_deserializer()
@@ -2558,20 +2563,6 @@ pub struct StrDeserializer<'a, E> {
     marker: PhantomData<E>,
 }
 
-impl<'a, E> IdentifierDeserializer<'a, E> for &'a str
-where
-    E: Error,
-{
-    type Deserializer = StrDeserializer<'a, E>;
-
-    fn from(self) -> Self::Deserializer {
-        StrDeserializer {
-            value: self,
-            marker: PhantomData,
-        }
-    }
-}
-
 impl<'de, 'a, E> Deserializer<'de> for StrDeserializer<'a, E>
 where
     E: Error,
@@ -2592,26 +2583,12 @@ where
     }
 }
 
-pub struct BytesDeserializer<'a, E> {
-    value: &'a [u8],
+pub struct BorrowedStrDeserializer<'de, E> {
+    value: &'de str,
     marker: PhantomData<E>,
 }
 
-impl<'a, E> IdentifierDeserializer<'a, E> for &'a [u8]
-where
-    E: Error,
-{
-    type Deserializer = BytesDeserializer<'a, E>;
-
-    fn from(self) -> Self::Deserializer {
-        BytesDeserializer {
-            value: self,
-            marker: PhantomData,
-        }
-    }
-}
-
-impl<'de, 'a, E> Deserializer<'de> for BytesDeserializer<'a, E>
+impl<'de, E> Deserializer<'de> for BorrowedStrDeserializer<'de, E>
 where
     E: Error,
 {
@@ -2621,7 +2598,7 @@ where
     where
         V: Visitor<'de>,
     {
-        visitor.visit_bytes(self.value)
+        visitor.visit_borrowed_str(self.value)
     }
 
     forward_to_deserialize_any! {
@@ -2631,6 +2608,56 @@ where
     }
 }
 
+impl<'a, E> IdentifierDeserializer<'a, E> for &'a str
+where
+    E: Error,
+{
+    type Deserializer = StrDeserializer<'a, E>;
+
+    fn from(self) -> Self::Deserializer {
+        StrDeserializer {
+            value: self,
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'de, E> IdentifierDeserializer<'de, E> for Borrowed<'de, str>
+where
+    E: Error,
+{
+    type Deserializer = BorrowedStrDeserializer<'de, E>;
+
+    fn from(self) -> Self::Deserializer {
+        BorrowedStrDeserializer {
+            value: self.0,
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'a, E> IdentifierDeserializer<'a, E> for &'a [u8]
+where
+    E: Error,
+{
+    type Deserializer = BytesDeserializer<'a, E>;
+
+    fn from(self) -> Self::Deserializer {
+        BytesDeserializer::new(self)
+    }
+}
+
+impl<'de, E> IdentifierDeserializer<'de, E> for Borrowed<'de, [u8]>
+where
+    E: Error,
+{
+    type Deserializer = BorrowedBytesDeserializer<'de, E>;
+
+    fn from(self) -> Self::Deserializer {
+        BorrowedBytesDeserializer::new(self.0)
+    }
+}
+
 /// A DeserializeSeed helper for implementing deserialize_in_place Visitors.
 ///
 /// Wraps a mutable reference and calls deserialize_in_place on it.

serde/src/private/doc.rs

@@ -1,3 +1,35 @@
+// Used only by Serde doc tests. Not public API.
+
+use lib::*;
+
+use ser;
+
+#[doc(hidden)]
+#[derive(Debug)]
+pub struct Error;
+
+impl ser::Error for Error {
+    fn custom<T>(_: T) -> Self
+    where
+        T: Display,
+    {
+        unimplemented!()
+    }
+}
+
+#[cfg(feature = "std")]
+impl error::Error for Error {
+    fn description(&self) -> &str {
+        unimplemented!()
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
+        unimplemented!()
+    }
+}
+
 #[doc(hidden)]
 #[macro_export]
 macro_rules! __private_serialize {
@@ -10,19 +42,6 @@ macro_rules! __private_serialize {
     };
 }
 
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __private_deserialize {
-    () => {
-        trait Deserialize<'de>: Sized {
-            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-            where
-                D: $crate::Deserializer<'de>;
-        }
-    };
-}
-
-/// Used only by Serde doc tests. Not public API.
 #[doc(hidden)]
 #[macro_export(local_inner_macros)]
 macro_rules! __serialize_unimplemented {

serde/src/private/mod.rs

@@ -1,8 +1,9 @@
-mod macros;
-
 pub mod de;
 pub mod ser;
 
+// FIXME: #[cfg(doctest)] once https://github.com/rust-lang/rust/issues/67295 is fixed.
+pub mod doc;
+
 pub use lib::clone::Clone;
 pub use lib::convert::{From, Into};
 pub use lib::default::Default;

serde/src/private/ser.rs

@@ -335,33 +335,6 @@ where
     }
 }
 
-/// Used only by Serde doc tests. Not public API.
-#[doc(hidden)]
-#[derive(Debug)]
-pub struct Error;
-
-impl ser::Error for Error {
-    fn custom<T>(_: T) -> Self
-    where
-        T: Display,
-    {
-        unimplemented!()
-    }
-}
-
-#[cfg(feature = "std")]
-impl error::Error for Error {
-    fn description(&self) -> &str {
-        unimplemented!()
-    }
-}
-
-impl Display for Error {
-    fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
-        unimplemented!()
-    }
-}
-
 #[cfg(any(feature = "std", feature = "alloc"))]
 mod content {
     use lib::*;
@@ -452,7 +425,6 @@ mod content {
         }
     }
 
-    #[derive(Debug)]
     pub enum Content {
         Bool(bool),
 

serde/src/ser/impossible.rs

@@ -17,7 +17,7 @@ use ser::{
 ///
 /// ```edition2018
 /// # use serde::ser::{Serializer, Impossible};
-/// # use serde::__private::ser::Error;
+/// # use serde::__private::doc::Error;
 /// #
 /// # struct MySerializer;
 /// #

serde/src/ser/mod.rs

@@ -711,7 +711,7 @@ pub trait Serializer: Sized {
     ///
     /// ```edition2018
     /// # use serde::ser::{Serializer, SerializeSeq};
-    /// # use serde::__private::ser::Error;
+    /// # use serde::__private::doc::Error;
     /// #
     /// # struct MySerializer;
     /// #

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.119" # remember to update html_root_url
+version = "1.0.122" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -22,7 +22,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0.58", features = ["visit"] }
+syn = "1.0.60"
 
 [dev-dependencies]
 serde = { version = "1.0", path = "../serde" }

serde_derive/src/bound.rs

@@ -2,7 +2,6 @@ use std::collections::HashSet;
 
 use syn;
 use syn::punctuated::{Pair, Punctuated};
-use syn::visit::{self, Visit};
 
 use internals::ast::{Container, Data};
 use internals::{attr, ungroup};
@@ -112,7 +111,8 @@ pub fn with_bound(
         // parameters.
         associated_type_usage: Vec<&'ast syn::TypePath>,
     }
-    impl<'ast> Visit<'ast> for FindTyParams<'ast> {
+
+    impl<'ast> FindTyParams<'ast> {
         fn visit_field(&mut self, field: &'ast syn::Field) {
             if let syn::Type::Path(ty) = ungroup(&field.ty) {
                 if let Some(Pair::Punctuated(t, _)) = ty.path.segments.pairs().next() {
@@ -138,7 +138,98 @@ pub fn with_bound(
                     self.relevant_type_params.insert(id.clone());
                 }
             }
-            visit::visit_path(self, path);
+            for segment in &path.segments {
+                self.visit_path_segment(segment);
+            }
+        }
+
+        // Everything below is simply traversing the syntax tree.
+
+        fn visit_type(&mut self, ty: &'ast syn::Type) {
+            match ty {
+                syn::Type::Array(ty) => self.visit_type(&ty.elem),
+                syn::Type::BareFn(ty) => {
+                    for arg in &ty.inputs {
+                        self.visit_type(&arg.ty);
+                    }
+                    self.visit_return_type(&ty.output);
+                }
+                syn::Type::Group(ty) => self.visit_type(&ty.elem),
+                syn::Type::ImplTrait(ty) => {
+                    for bound in &ty.bounds {
+                        self.visit_type_param_bound(bound);
+                    }
+                }
+                syn::Type::Macro(ty) => self.visit_macro(&ty.mac),
+                syn::Type::Paren(ty) => self.visit_type(&ty.elem),
+                syn::Type::Path(ty) => {
+                    if let Some(qself) = &ty.qself {
+                        self.visit_type(&qself.ty);
+                    }
+                    self.visit_path(&ty.path);
+                }
+                syn::Type::Ptr(ty) => self.visit_type(&ty.elem),
+                syn::Type::Reference(ty) => self.visit_type(&ty.elem),
+                syn::Type::Slice(ty) => self.visit_type(&ty.elem),
+                syn::Type::TraitObject(ty) => {
+                    for bound in &ty.bounds {
+                        self.visit_type_param_bound(bound);
+                    }
+                }
+                syn::Type::Tuple(ty) => {
+                    for elem in &ty.elems {
+                        self.visit_type(elem);
+                    }
+                }
+
+                syn::Type::Infer(_) | syn::Type::Never(_) | syn::Type::Verbatim(_) => {}
+
+                #[cfg(test)]
+                syn::Type::__TestExhaustive(_) => unimplemented!(),
+                #[cfg(not(test))]
+                _ => {}
+            }
+        }
+
+        fn visit_path_segment(&mut self, segment: &'ast syn::PathSegment) {
+            self.visit_path_arguments(&segment.arguments);
+        }
+
+        fn visit_path_arguments(&mut self, arguments: &'ast syn::PathArguments) {
+            match arguments {
+                syn::PathArguments::None => {}
+                syn::PathArguments::AngleBracketed(arguments) => {
+                    for arg in &arguments.args {
+                        match arg {
+                            syn::GenericArgument::Type(arg) => self.visit_type(arg),
+                            syn::GenericArgument::Binding(arg) => self.visit_type(&arg.ty),
+                            syn::GenericArgument::Lifetime(_)
+                            | syn::GenericArgument::Constraint(_)
+                            | syn::GenericArgument::Const(_) => {}
+                        }
+                    }
+                }
+                syn::PathArguments::Parenthesized(arguments) => {
+                    for argument in &arguments.inputs {
+                        self.visit_type(argument);
+                    }
+                    self.visit_return_type(&arguments.output);
+                }
+            }
+        }
+
+        fn visit_return_type(&mut self, return_type: &'ast syn::ReturnType) {
+            match return_type {
+                syn::ReturnType::Default => {}
+                syn::ReturnType::Type(_, output) => self.visit_type(output),
+            }
+        }
+
+        fn visit_type_param_bound(&mut self, bound: &'ast syn::TypeParamBound) {
+            match bound {
+                syn::TypeParamBound::Trait(bound) => self.visit_path(&bound.path),
+                syn::TypeParamBound::Lifetime(_) => {}
+            }
         }
 
         // Type parameter should not be considered used by a macro path.

serde_derive/src/de.rs

@@ -402,6 +402,7 @@ fn deserialize_unit_struct(params: &Parameters, cattrs: &attr::Container) -> Fra
     let type_name = cattrs.name().deserialize_name();
 
     let expecting = format!("unit struct {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     quote_block! {
         struct __Visitor;
@@ -459,6 +460,7 @@ fn deserialize_tuple(
         Some(variant_ident) => format!("tuple variant {}::{}", params.type_name(), variant_ident),
         None => format!("tuple struct {}", params.type_name()),
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let nfields = fields.len();
 
@@ -545,6 +547,7 @@ fn deserialize_tuple_in_place(
         Some(variant_ident) => format!("tuple variant {}::{}", params.type_name(), variant_ident),
         None => format!("tuple struct {}", params.type_name()),
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let nfields = fields.len();
 
@@ -633,6 +636,7 @@ fn deserialize_seq(
     } else {
         format!("{} with {} elements", expecting, deserialized_count)
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let mut index_in_seq = 0_usize;
     let let_values = vars.clone().zip(fields).map(|(var, field)| {
@@ -735,6 +739,7 @@ fn deserialize_seq_in_place(
     } else {
         format!("{} with {} elements", expecting, deserialized_count)
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let mut index_in_seq = 0usize;
     let write_values = fields.iter().map(|field| {
@@ -910,6 +915,7 @@ fn deserialize_struct(
         Some(variant_ident) => format!("struct variant {}::{}", params.type_name(), variant_ident),
         None => format!("struct {}", params.type_name()),
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let visit_seq = Stmts(deserialize_seq(
         &type_path, params, fields, true, cattrs, &expecting,
@@ -1051,6 +1057,7 @@ fn deserialize_struct_in_place(
         Some(variant_ident) => format!("struct variant {}::{}", params.type_name(), variant_ident),
         None => format!("struct {}", params.type_name()),
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, &expecting));
 
@@ -1203,6 +1210,7 @@ fn deserialize_externally_tagged_enum(
 
     let type_name = cattrs.name().deserialize_name();
     let expecting = format!("enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
 
@@ -1312,6 +1320,9 @@ fn deserialize_internally_tagged_enum(
             }
         });
 
+    let expecting = format!("internally tagged enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
     quote_block! {
         #variant_visitor
 
@@ -1319,7 +1330,7 @@ fn deserialize_internally_tagged_enum(
 
         let __tagged = try!(_serde::Deserializer::deserialize_any(
             __deserializer,
-            _serde::__private::de::TaggedContentVisitor::<__Field>::new(#tag)));
+            _serde::__private::de::TaggedContentVisitor::<__Field>::new(#tag, #expecting)));
 
         match __tagged.tag {
             #(#variant_arms)*
@@ -1362,6 +1373,7 @@ fn deserialize_adjacently_tagged_enum(
         .collect();
 
     let expecting = format!("adjacently tagged enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
     let type_name = cattrs.name().deserialize_name();
     let deny_unknown_fields = cattrs.deny_unknown_fields();
 
@@ -1653,6 +1665,7 @@ fn deserialize_untagged_enum(
         "data did not match any variant of untagged enum {}",
         params.type_name()
     );
+    let fallthrough_msg = cattrs.expecting().unwrap_or(&fallthrough_msg);
 
     quote_block! {
         let __content = try!(<_serde::__private::de::Content as _serde::Deserialize>::deserialize(__deserializer));
@@ -1909,7 +1922,9 @@ fn deserialize_generated_identifier(
         fields,
         is_variant,
         fallthrough,
+        None,
         !is_variant && cattrs.has_flatten(),
+        None,
     ));
 
     let lifetime = if !is_variant && cattrs.has_flatten() {
@@ -1945,6 +1960,8 @@ fn deserialize_generated_identifier(
     }
 }
 
+// Generates `Deserialize::deserialize` body for an enum with
+// `serde(field_identifier)` or `serde(variant_identifier)` attribute.
 fn deserialize_custom_identifier(
     params: &Parameters,
     variants: &[Variant],
@@ -1959,26 +1976,38 @@ fn deserialize_custom_identifier(
     let this = &params.this;
     let this = quote!(#this);
 
-    let (ordinary, fallthrough) = if let Some(last) = variants.last() {
+    let (ordinary, fallthrough, fallthrough_borrowed) = if let Some(last) = variants.last() {
         let last_ident = &last.ident;
         if last.attrs.other() {
+            // Process `serde(other)` attribute. It would always be found on the
+            // last variant (checked in `check_identifier`), so all preceding
+            // are ordinary variants.
             let ordinary = &variants[..variants.len() - 1];
             let fallthrough = quote!(_serde::__private::Ok(#this::#last_ident));
-            (ordinary, Some(fallthrough))
+            (ordinary, Some(fallthrough), None)
         } else if let Style::Newtype = last.style {
             let ordinary = &variants[..variants.len() - 1];
-            let deserializer = quote!(_serde::__private::de::IdentifierDeserializer::from(__value));
-            let fallthrough = quote! {
-                _serde::__private::Result::map(
-                    _serde::Deserialize::deserialize(#deserializer),
-                    #this::#last_ident)
+            let fallthrough = |value| {
+                quote! {
+                    _serde::__private::Result::map(
+                        _serde::Deserialize::deserialize(
+                            _serde::__private::de::IdentifierDeserializer::from(#value)
+                        ),
+                        #this::#last_ident)
+                }
             };
-            (ordinary, Some(fallthrough))
+            (
+                ordinary,
+                Some(fallthrough(quote!(__value))),
+                Some(fallthrough(quote!(_serde::__private::de::Borrowed(
+                    __value
+                )))),
+            )
         } else {
-            (variants, None)
+            (variants, None, None)
         }
     } else {
-        (variants, None)
+        (variants, None, None)
     };
 
     let names_idents: Vec<_> = ordinary
@@ -2016,7 +2045,9 @@ fn deserialize_custom_identifier(
         &names_idents,
         is_variant,
         fallthrough,
+        fallthrough_borrowed,
         false,
+        cattrs.expecting(),
     ));
 
     quote_block! {
@@ -2046,21 +2077,20 @@ fn deserialize_identifier(
     fields: &[(String, Ident, Vec<String>)],
     is_variant: bool,
     fallthrough: Option<TokenStream>,
+    fallthrough_borrowed: Option<TokenStream>,
     collect_other_fields: bool,
+    expecting: Option<&str>,
 ) -> Fragment {
     let mut flat_fields = Vec::new();
     for (_, ident, aliases) in fields {
         flat_fields.extend(aliases.iter().map(|alias| (alias, ident)))
     }
 
-    let field_strs = flat_fields.iter().map(|(name, _)| name);
-    let field_borrowed_strs = flat_fields.iter().map(|(name, _)| name);
-    let field_bytes = flat_fields
+    let field_strs: &Vec<_> = &flat_fields.iter().map(|(name, _)| name).collect();
+    let field_bytes: &Vec<_> = &flat_fields
         .iter()
-        .map(|(name, _)| Literal::byte_string(name.as_bytes()));
-    let field_borrowed_bytes = flat_fields
-        .iter()
-        .map(|(name, _)| Literal::byte_string(name.as_bytes()));
+        .map(|(name, _)| Literal::byte_string(name.as_bytes()))
+        .collect();
 
     let constructors: &Vec<_> = &flat_fields
         .iter()
@@ -2071,11 +2101,11 @@ fn deserialize_identifier(
         .map(|(_, ident, _)| quote!(#this::#ident))
         .collect();
 
-    let expecting = if is_variant {
+    let expecting = expecting.unwrap_or(if is_variant {
         "variant identifier"
     } else {
         "field identifier"
-    };
+    });
 
     let index_expecting = if is_variant { "variant" } else { "field" };
 
@@ -2111,20 +2141,36 @@ fn deserialize_identifier(
         (None, None, None, None)
     };
 
-    let fallthrough_arm = if let Some(fallthrough) = fallthrough {
+    let fallthrough_arm_tokens;
+    let fallthrough_arm = if let Some(fallthrough) = &fallthrough {
         fallthrough
     } else if is_variant {
-        quote! {
+        fallthrough_arm_tokens = quote! {
             _serde::__private::Err(_serde::de::Error::unknown_variant(__value, VARIANTS))
-        }
+        };
+        &fallthrough_arm_tokens
     } else {
-        quote! {
+        fallthrough_arm_tokens = quote! {
             _serde::__private::Err(_serde::de::Error::unknown_field(__value, FIELDS))
-        }
+        };
+        &fallthrough_arm_tokens
+    };
+
+    let u64_fallthrough_arm_tokens;
+    let u64_fallthrough_arm = if let Some(fallthrough) = &fallthrough {
+        fallthrough
+    } else {
+        let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
+        u64_fallthrough_arm_tokens = quote! {
+            _serde::__private::Err(_serde::de::Error::invalid_value(
+                _serde::de::Unexpected::Unsigned(__value),
+                &#fallthrough_msg,
+            ))
+        };
+        &u64_fallthrough_arm_tokens
     };
 
     let variant_indices = 0_u64..;
-    let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
     let visit_other = if collect_other_fields {
         quote! {
             fn visit_bool<__E>(self, __value: bool) -> _serde::__private::Result<Self::Value, __E>
@@ -2217,37 +2263,6 @@ fn deserialize_identifier(
             {
                 _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::Unit))
             }
-
-            fn visit_borrowed_str<__E>(self, __value: &'de str) -> _serde::__private::Result<Self::Value, __E>
-            where
-                __E: _serde::de::Error,
-            {
-                match __value {
-                    #(
-                        #field_borrowed_strs => _serde::__private::Ok(#constructors),
-                    )*
-                    _ => {
-                        #value_as_borrowed_str_content
-                        #fallthrough_arm
-                    }
-                }
-            }
-
-            fn visit_borrowed_bytes<__E>(self, __value: &'de [u8]) -> _serde::__private::Result<Self::Value, __E>
-            where
-                __E: _serde::de::Error,
-            {
-                match __value {
-                    #(
-                        #field_borrowed_bytes => _serde::__private::Ok(#constructors),
-                    )*
-                    _ => {
-                        #bytes_to_str
-                        #value_as_borrowed_bytes_content
-                        #fallthrough_arm
-                    }
-                }
-            }
         }
     } else {
         quote! {
@@ -2259,15 +2274,50 @@ fn deserialize_identifier(
                     #(
                         #variant_indices => _serde::__private::Ok(#main_constructors),
                     )*
-                    _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                        _serde::de::Unexpected::Unsigned(__value),
-                        &#fallthrough_msg,
-                    ))
+                    _ => #u64_fallthrough_arm,
                 }
             }
         }
     };
 
+    let visit_borrowed = if fallthrough_borrowed.is_some() || collect_other_fields {
+        let fallthrough_borrowed_arm = fallthrough_borrowed.as_ref().unwrap_or(&fallthrough_arm);
+        Some(quote! {
+            fn visit_borrowed_str<__E>(self, __value: &'de str) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                match __value {
+                    #(
+                        #field_strs => _serde::__private::Ok(#constructors),
+                    )*
+                    _ => {
+                        #value_as_borrowed_str_content
+                        #fallthrough_borrowed_arm
+                    }
+                }
+            }
+
+            fn visit_borrowed_bytes<__E>(self, __value: &'de [u8]) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                match __value {
+                    #(
+                        #field_bytes => _serde::__private::Ok(#constructors),
+                    )*
+                    _ => {
+                        #bytes_to_str
+                        #value_as_borrowed_bytes_content
+                        #fallthrough_borrowed_arm
+                    }
+                }
+            }
+        })
+    } else {
+        None
+    };
+
     quote_block! {
         fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
             _serde::__private::Formatter::write_str(__formatter, #expecting)
@@ -2305,6 +2355,8 @@ fn deserialize_identifier(
                 }
             }
         }
+
+        #visit_borrowed
     }
 }
 

serde_derive/src/internals/attr.rs

@@ -4,7 +4,6 @@ use proc_macro2::{Group, Span, TokenStream, TokenTree};
 use quote::ToTokens;
 use std::borrow::Cow;
 use std::collections::BTreeSet;
-use std::str::FromStr;
 use syn;
 use syn::parse::{self, Parse, ParseStream};
 use syn::punctuated::Punctuated;
@@ -223,6 +222,8 @@ pub struct Container {
     has_flatten: bool,
     serde_path: Option<syn::Path>,
     is_packed: bool,
+    /// Error message generated when type can't be deserialized
+    expecting: Option<String>,
 }
 
 /// Styles of representing an enum.
@@ -305,6 +306,7 @@ impl Container {
         let mut field_identifier = BoolAttr::none(cx, FIELD_IDENTIFIER);
         let mut variant_identifier = BoolAttr::none(cx, VARIANT_IDENTIFIER);
         let mut serde_path = Attr::none(cx, CRATE);
+        let mut expecting = Attr::none(cx, EXPECTING);
 
         for meta_item in item
             .attrs
@@ -337,13 +339,7 @@ impl Container {
                                 rename_all_ser_rule.set(&m.path, rename_rule);
                                 rename_all_de_rule.set(&m.path, rename_rule);
                             }
-                            Err(()) => cx.error_spanned_by(
-                                s,
-                                format!(
-                                    "unknown rename rule for #[serde(rename_all = {:?})]",
-                                    s.value(),
-                                ),
-                            ),
+                            Err(err) => cx.error_spanned_by(s, err),
                         }
                     }
                 }
@@ -354,25 +350,13 @@ impl Container {
                         if let Some(ser) = ser {
                             match RenameRule::from_str(&ser.value()) {
                                 Ok(rename_rule) => rename_all_ser_rule.set(&m.path, rename_rule),
-                                Err(()) => cx.error_spanned_by(
-                                    ser,
-                                    format!(
-                                        "unknown rename rule for #[serde(rename_all = {:?})]",
-                                        ser.value(),
-                                    ),
-                                ),
+                                Err(err) => cx.error_spanned_by(ser, err),
                             }
                         }
                         if let Some(de) = de {
                             match RenameRule::from_str(&de.value()) {
                                 Ok(rename_rule) => rename_all_de_rule.set(&m.path, rename_rule),
-                                Err(()) => cx.error_spanned_by(
-                                    de,
-                                    format!(
-                                        "unknown rename rule for #[serde(rename_all = {:?})]",
-                                        de.value(),
-                                    ),
-                                ),
+                                Err(err) => cx.error_spanned_by(de, err),
                             }
                         }
                     }
@@ -575,6 +559,13 @@ impl Container {
                     }
                 }
 
+                // Parse `#[serde(expecting = "a message")]`
+                Meta(NameValue(m)) if m.path == EXPECTING => {
+                    if let Ok(s) = get_lit_str(cx, EXPECTING, &m.lit) {
+                        expecting.set(&m.path, s.value());
+                    }
+                }
+
                 Meta(meta_item) => {
                     let path = meta_item
                         .path()
@@ -627,6 +618,7 @@ impl Container {
             has_flatten: false,
             serde_path: serde_path.get(),
             is_packed,
+            expecting: expecting.get(),
         }
     }
 
@@ -702,6 +694,12 @@ impl Container {
         self.custom_serde_path()
             .map_or_else(|| Cow::Owned(parse_quote!(_serde)), Cow::Borrowed)
     }
+
+    /// Error message generated when type can't be deserialized.
+    /// If `None`, default message will be used
+    pub fn expecting(&self) -> Option<&str> {
+        self.expecting.as_ref().map(String::as_ref)
+    }
 }
 
 fn decide_tag(
@@ -914,13 +912,7 @@ impl Variant {
                                 rename_all_ser_rule.set(&m.path, rename_rule);
                                 rename_all_de_rule.set(&m.path, rename_rule);
                             }
-                            Err(()) => cx.error_spanned_by(
-                                s,
-                                format!(
-                                    "unknown rename rule for #[serde(rename_all = {:?})]",
-                                    s.value()
-                                ),
-                            ),
+                            Err(err) => cx.error_spanned_by(s, err),
                         }
                     }
                 }
@@ -931,25 +923,13 @@ impl Variant {
                         if let Some(ser) = ser {
                             match RenameRule::from_str(&ser.value()) {
                                 Ok(rename_rule) => rename_all_ser_rule.set(&m.path, rename_rule),
-                                Err(()) => cx.error_spanned_by(
-                                    ser,
-                                    format!(
-                                        "unknown rename rule for #[serde(rename_all = {:?})]",
-                                        ser.value(),
-                                    ),
-                                ),
+                                Err(err) => cx.error_spanned_by(ser, err),
                             }
                         }
                         if let Some(de) = de {
                             match RenameRule::from_str(&de.value()) {
                                 Ok(rename_rule) => rename_all_de_rule.set(&m.path, rename_rule),
-                                Err(()) => cx.error_spanned_by(
-                                    de,
-                                    format!(
-                                        "unknown rename rule for #[serde(rename_all = {:?})]",
-                                        de.value(),
-                                    ),
-                                ),
+                                Err(err) => cx.error_spanned_by(de, err),
                             }
                         }
                     }

serde_derive/src/internals/case.rs

@@ -5,7 +5,7 @@
 #[allow(deprecated, unused_imports)]
 use std::ascii::AsciiExt;
 
-use std::str::FromStr;
+use std::fmt::{self, Debug, Display};
 
 use self::RenameRule::*;
 
@@ -17,7 +17,7 @@ pub enum RenameRule {
     /// Rename direct children to "lowercase" style.
     LowerCase,
     /// Rename direct children to "UPPERCASE" style.
-    UPPERCASE,
+    UpperCase,
     /// Rename direct children to "PascalCase" style, as typically used for
     /// enum variants.
     PascalCase,
@@ -35,13 +35,35 @@ pub enum RenameRule {
     ScreamingKebabCase,
 }
 
+static RENAME_RULES: &[(&str, RenameRule)] = &[
+    ("lowercase", LowerCase),
+    ("UPPERCASE", UpperCase),
+    ("PascalCase", PascalCase),
+    ("camelCase", CamelCase),
+    ("snake_case", SnakeCase),
+    ("SCREAMING_SNAKE_CASE", ScreamingSnakeCase),
+    ("kebab-case", KebabCase),
+    ("SCREAMING-KEBAB-CASE", ScreamingKebabCase),
+];
+
 impl RenameRule {
+    pub fn from_str(rename_all_str: &str) -> Result<Self, ParseError> {
+        for (name, rule) in RENAME_RULES {
+            if rename_all_str == *name {
+                return Ok(*rule);
+            }
+        }
+        Err(ParseError {
+            unknown: rename_all_str,
+        })
+    }
+
     /// Apply a renaming rule to an enum variant, returning the version expected in the source.
     pub fn apply_to_variant(&self, variant: &str) -> String {
         match *self {
             None | PascalCase => variant.to_owned(),
             LowerCase => variant.to_ascii_lowercase(),
-            UPPERCASE => variant.to_ascii_uppercase(),
+            UpperCase => variant.to_ascii_uppercase(),
             CamelCase => variant[..1].to_ascii_lowercase() + &variant[1..],
             SnakeCase => {
                 let mut snake = String::new();
@@ -65,7 +87,7 @@ impl RenameRule {
     pub fn apply_to_field(&self, field: &str) -> String {
         match *self {
             None | LowerCase | SnakeCase => field.to_owned(),
-            UPPERCASE => field.to_ascii_uppercase(),
+            UpperCase => field.to_ascii_uppercase(),
             PascalCase => {
                 let mut pascal = String::new();
                 let mut capitalize = true;
@@ -92,21 +114,22 @@ impl RenameRule {
     }
 }
 
-impl FromStr for RenameRule {
-    type Err = ();
+pub struct ParseError<'a> {
+    unknown: &'a str,
+}
 
-    fn from_str(rename_all_str: &str) -> Result<Self, Self::Err> {
-        match rename_all_str {
-            "lowercase" => Ok(LowerCase),
-            "UPPERCASE" => Ok(UPPERCASE),
-            "PascalCase" => Ok(PascalCase),
-            "camelCase" => Ok(CamelCase),
-            "snake_case" => Ok(SnakeCase),
-            "SCREAMING_SNAKE_CASE" => Ok(ScreamingSnakeCase),
-            "kebab-case" => Ok(KebabCase),
-            "SCREAMING-KEBAB-CASE" => Ok(ScreamingKebabCase),
-            _ => Err(()),
+impl<'a> Display for ParseError<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("unknown rename rule `rename_all = ")?;
+        Debug::fmt(self.unknown, f)?;
+        f.write_str("`, expected one of ")?;
+        for (i, (name, _rule)) in RENAME_RULES.iter().enumerate() {
+            if i > 0 {
+                f.write_str(", ")?;
+            }
+            Debug::fmt(name, f)?;
         }
+        Ok(())
     }
 }
 
@@ -131,7 +154,7 @@ fn rename_variants() {
     ] {
         assert_eq!(None.apply_to_variant(original), original);
         assert_eq!(LowerCase.apply_to_variant(original), lower);
-        assert_eq!(UPPERCASE.apply_to_variant(original), upper);
+        assert_eq!(UpperCase.apply_to_variant(original), upper);
         assert_eq!(PascalCase.apply_to_variant(original), original);
         assert_eq!(CamelCase.apply_to_variant(original), camel);
         assert_eq!(SnakeCase.apply_to_variant(original), snake);
@@ -163,7 +186,7 @@ fn rename_fields() {
         ("z42", "Z42", "Z42", "z42", "Z42", "z42", "Z42"),
     ] {
         assert_eq!(None.apply_to_field(original), original);
-        assert_eq!(UPPERCASE.apply_to_field(original), upper);
+        assert_eq!(UpperCase.apply_to_field(original), upper);
         assert_eq!(PascalCase.apply_to_field(original), pascal);
         assert_eq!(CamelCase.apply_to_field(original), camel);
         assert_eq!(SnakeCase.apply_to_field(original), original);

serde_derive/src/internals/symbol.rs

@@ -35,6 +35,7 @@ pub const TRY_FROM: Symbol = Symbol("try_from");
 pub const UNTAGGED: Symbol = Symbol("untagged");
 pub const VARIANT_IDENTIFIER: Symbol = Symbol("variant_identifier");
 pub const WITH: Symbol = Symbol("with");
+pub const EXPECTING: Symbol = Symbol("expecting");
 
 impl PartialEq<Symbol> for Ident {
     fn eq(&self, word: &Symbol) -> bool {

serde_derive/src/lib.rs

@@ -13,7 +13,7 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.119")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.122")]
 #![allow(unknown_lints, bare_trait_objects)]
 #![deny(clippy::all, clippy::pedantic)]
 // Ignored clippy lints
@@ -48,6 +48,7 @@
     clippy::struct_excessive_bools,
     clippy::too_many_lines,
     clippy::unseparated_literal_suffix,
+    clippy::unused_self,
     clippy::use_self,
     clippy::wildcard_imports
 )]

serde_derive_internals/Cargo.toml

@@ -16,7 +16,7 @@ path = "lib.rs"
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0.33", default-features = false, features = ["derive", "parsing", "printing", "clone-impls"] }
+syn = { version = "1.0.60", default-features = false, features = ["derive", "parsing", "printing", "clone-impls"] }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]

serde_derive_internals/lib.rs

@@ -1,17 +1,28 @@
 #![doc(html_root_url = "https://docs.rs/serde_derive_internals/0.25.0")]
 #![allow(unknown_lints, bare_trait_objects)]
-#![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
-#![cfg_attr(
-    feature = "cargo-clippy",
-    allow(
-        cognitive_complexity,
-        redundant_field_names,
-        result_unit_err,
-        trivially_copy_pass_by_ref,
-        wildcard_in_or_patterns,
-        // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
-        unnested_or_patterns,
-    )
+#![deny(clippy::all, clippy::pedantic)]
+// Ignored clippy lints
+#![allow(
+    clippy::cognitive_complexity,
+    clippy::redundant_field_names,
+    clippy::result_unit_err,
+    clippy::should_implement_trait,
+    clippy::trivially_copy_pass_by_ref,
+    clippy::wildcard_in_or_patterns,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
+    clippy::unnested_or_patterns,
+)]
+// Ignored clippy_pedantic lints
+#![allow(
+    clippy::doc_markdown,
+    clippy::enum_glob_use,
+    clippy::items_after_statements,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::must_use_candidate,
+    clippy::struct_excessive_bools,
+    clippy::too_many_lines,
+    clippy::wildcard_imports
 )]
 
 #[macro_use]

serde_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_test"
-version = "1.0.119" # remember to update html_root_url
+version = "1.0.122" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Token De/Serializer for testing De/Serialize implementations"

serde_test/build.rs

@@ -0,0 +1,30 @@
+use std::env;
+use std::process::Command;
+use std::str;
+
+// 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,
+    };
+
+    // #[track_caller] stabilized in Rust 1.46:
+    // https://blog.rust-lang.org/2020/08/27/Rust-1.46.0.html#track_caller
+    if minor >= 46 {
+        println!("cargo:rustc-cfg=track_caller");
+    }
+}
+
+fn rustc_minor_version() -> Option<u32> {
+    let rustc = env::var_os("RUSTC")?;
+    let output = Command::new(rustc).arg("--version").output().ok()?;
+    let version = str::from_utf8(&output.stdout).ok()?;
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return None;
+    }
+    pieces.next()?.parse().ok()
+}

serde_test/src/assert.rs

@@ -28,6 +28,7 @@ use std::fmt::Debug;
 ///     Token::StructEnd,
 /// ]);
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_tokens<'de, T>(value: &T, tokens: &'de [Token])
 where
     T: Serialize + Deserialize<'de> + PartialEq + Debug,
@@ -58,6 +59,7 @@ where
 ///     Token::StructEnd,
 /// ]);
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_ser_tokens<T>(value: &T, tokens: &[Token])
 where
     T: Serialize,
@@ -110,6 +112,7 @@ where
 ///     assert_ser_tokens_error(&example, expected, error);
 /// }
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_ser_tokens_error<T>(value: &T, tokens: &[Token], error: &str)
 where
     T: Serialize,
@@ -147,6 +150,7 @@ where
 ///     Token::StructEnd,
 /// ]);
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_de_tokens<'de, T>(value: &T, tokens: &'de [Token])
 where
     T: Deserialize<'de> + PartialEq + Debug,
@@ -199,6 +203,7 @@ where
 ///     "unknown field `x`, expected `a` or `b`",
 /// );
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_de_tokens_error<'de, T>(tokens: &'de [Token], error: &str)
 where
     T: Deserialize<'de>,

serde_test/src/configure.rs

@@ -777,6 +777,17 @@ macro_rules! impl_deserializer {
             {
                 self.0.next_value_seed($wrapper(seed))
             }
+            fn next_entry_seed<K, V>(
+                &mut self,
+                kseed: K,
+                vseed: V,
+            ) -> Result<Option<(K::Value, V::Value)>, D::Error>
+            where
+                K: DeserializeSeed<'de>,
+                V: DeserializeSeed<'de>,
+            {
+                self.0.next_entry_seed($wrapper(kseed), $wrapper(vseed))
+            }
             fn size_hint(&self) -> Option<usize> {
                 self.0.size_hint()
             }

serde_test/src/de.rs

@@ -168,14 +168,42 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
                         self.next_token();
                         visitor.visit_str(variant)
                     }
+                    (Token::BorrowedStr(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_borrowed_str(variant)
+                    }
+                    (Token::String(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_string(variant.to_string())
+                    }
                     (Token::Bytes(variant), Token::Unit) => {
                         self.next_token();
                         visitor.visit_bytes(variant)
                     }
+                    (Token::BorrowedBytes(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_borrowed_bytes(variant)
+                    }
+                    (Token::ByteBuf(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_byte_buf(variant.to_vec())
+                    }
+                    (Token::U8(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u8(variant)
+                    }
+                    (Token::U16(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u16(variant)
+                    }
                     (Token::U32(variant), Token::Unit) => {
                         self.next_token();
                         visitor.visit_u32(variant)
                     }
+                    (Token::U64(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u64(variant)
+                    }
                     (variant, Token::Unit) => unexpected!(variant),
                     (variant, _) => {
                         visitor.visit_map(EnumMapVisitor::new(self, variant, EnumFormat::Any))
@@ -250,9 +278,7 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
             {
                 visitor.visit_enum(DeserializerEnumVisitor { de: self })
             }
-            _ => {
-                unexpected!(self.next_token());
-            }
+            _ => self.deserialize_any(visitor),
         }
     }
 

serde_test/src/lib.rs

@@ -144,7 +144,7 @@
 //! # }
 //! ```
 
-#![doc(html_root_url = "https://docs.rs/serde_test/1.0.119")]
+#![doc(html_root_url = "https://docs.rs/serde_test/1.0.122")]
 #![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Ignored clippy lints
@@ -158,6 +158,7 @@
         module_name_repetitions,
         must_use_candidate,
         redundant_field_names,
+        too_many_lines,
         use_debug,
         use_self
     )

serde_test/src/ser.rs

@@ -32,18 +32,18 @@ impl<'a> Serializer<'a> {
 }
 
 macro_rules! assert_next_token {
-    ($ser:expr, $expected:ident) => {
-        assert_next_token!($ser, stringify!($expected), Token::$expected, true);
+    ($ser:expr, $actual:ident) => {
+        assert_next_token!($ser, stringify!($actual), Token::$actual, true);
     };
-    ($ser:expr, $expected:ident($v:expr)) => {
+    ($ser:expr, $actual:ident($v:expr)) => {
         assert_next_token!(
             $ser,
-            format_args!(concat!(stringify!($expected), "({:?})"), $v),
-            Token::$expected(v),
+            format_args!(concat!(stringify!($actual), "({:?})"), $v),
+            Token::$actual(v),
             v == $v
         );
     };
-    ($ser:expr, $expected:ident { $($k:ident),* }) => {
+    ($ser:expr, $actual:ident { $($k:ident),* }) => {
         let compare = ($($k,)*);
         let field_format = || {
             use std::fmt::Write;
@@ -55,21 +55,21 @@ macro_rules! assert_next_token {
         };
         assert_next_token!(
             $ser,
-            format_args!(concat!(stringify!($expected), " {{ {}}}"), field_format()),
-            Token::$expected { $($k),* },
+            format_args!(concat!(stringify!($actual), " {{ {}}}"), field_format()),
+            Token::$actual { $($k),* },
             ($($k,)*) == compare
         );
     };
-    ($ser:expr, $expected:expr, $pat:pat, $guard:expr) => {
+    ($ser:expr, $actual:expr, $pat:pat, $guard:expr) => {
         match $ser.next_token() {
             Some($pat) if $guard => {}
-            Some(other) => {
+            Some(expected) => {
                 panic!("expected Token::{} but serialized as {}",
-                       $expected, other);
+                       expected, $actual);
             }
             None => {
-                panic!("expected Token::{} after end of serialized tokens",
-                       $expected);
+                panic!("expected end of tokens, but {} was serialized",
+                       $actual);
             }
         }
     };

test_suite/tests/expand/de_enum.expanded.rs

@@ -573,12 +573,7 @@ const _: () = {
                                         1u64 => _serde::__private::Ok(__Field::__field1),
                                         2u64 => _serde::__private::Ok(__Field::__field2),
                                         3u64 => _serde::__private::Ok(__Field::__field3),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 4",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
@@ -1081,12 +1076,7 @@ const _: () = {
                                         1u64 => _serde::__private::Ok(__Field::__field1),
                                         2u64 => _serde::__private::Ok(__Field::__field2),
                                         3u64 => _serde::__private::Ok(__Field::__field3),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 4",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(

test_suite/tests/expand/default_ty_param.expanded.rs

@@ -77,10 +77,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::__private::Ok(__Field::__field0),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(
@@ -260,10 +257,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::__private::Ok(__Field::__field0),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(

test_suite/tests/expand/generic_enum.expanded.rs

@@ -357,12 +357,7 @@ const _: () = {
                                     match __value {
                                         0u64 => _serde::__private::Ok(__Field::__field0),
                                         1u64 => _serde::__private::Ok(__Field::__field1),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 2",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(

test_suite/tests/expand/generic_struct.expanded.rs

@@ -73,10 +73,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::__private::Ok(__Field::__field0),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(
@@ -256,10 +253,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::__private::Ok(__Field::__field0),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(

test_suite/tests/expand/lifetimes.expanded.rs

@@ -244,12 +244,7 @@ const _: () = {
                                 {
                                     match __value {
                                         0u64 => _serde::__private::Ok(__Field::__field0),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 1",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
@@ -433,12 +428,7 @@ const _: () = {
                                 {
                                     match __value {
                                         0u64 => _serde::__private::Ok(__Field::__field0),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 1",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(

test_suite/tests/expand/named_map.expanded.rs

@@ -100,10 +100,7 @@ const _: () = {
                         0u64 => _serde::__private::Ok(__Field::__field0),
                         1u64 => _serde::__private::Ok(__Field::__field1),
                         2u64 => _serde::__private::Ok(__Field::__field2),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 3",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(
@@ -387,10 +384,7 @@ const _: () = {
                         0u64 => _serde::__private::Ok(__Field::__field0),
                         1u64 => _serde::__private::Ok(__Field::__field1),
                         2u64 => _serde::__private::Ok(__Field::__field2),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 3",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(

test_suite/tests/test_annotations.rs

@@ -2637,3 +2637,171 @@ fn test_flatten_any_after_flatten_struct() {
         ],
     );
 }
+
+#[test]
+fn test_expecting_message() {
+    #[derive(Deserialize, PartialEq, Debug)]
+    #[serde(expecting = "something strange...")]
+    struct Unit;
+
+    #[derive(Deserialize)]
+    #[serde(expecting = "something strange...")]
+    struct Newtype(bool);
+
+    #[derive(Deserialize)]
+    #[serde(expecting = "something strange...")]
+    struct Tuple(u32, bool);
+
+    #[derive(Deserialize)]
+    #[serde(expecting = "something strange...")]
+    struct Struct {
+        question: String,
+        answer: u32,
+    }
+
+    assert_de_tokens_error::<Unit>(
+        &[Token::Str("Unit")],
+        r#"invalid type: string "Unit", expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<Newtype>(
+        &[Token::Str("Newtype")],
+        r#"invalid type: string "Newtype", expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<Tuple>(
+        &[Token::Str("Tuple")],
+        r#"invalid type: string "Tuple", expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<Struct>(
+        &[Token::Str("Struct")],
+        r#"invalid type: string "Struct", expected something strange..."#,
+    );
+}
+
+#[test]
+fn test_expecting_message_externally_tagged_enum() {
+    #[derive(Deserialize)]
+    #[serde(expecting = "something strange...")]
+    enum Enum {
+        ExternallyTagged,
+    }
+
+    assert_de_tokens_error::<Enum>(
+        &[Token::Str("ExternallyTagged")],
+        r#"invalid type: string "ExternallyTagged", expected something strange..."#,
+    );
+
+    // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
+    assert_de_tokens_error::<Enum>(
+        &[Token::Enum { name: "Enum" }, Token::Unit],
+        r#"invalid type: unit value, expected variant identifier"#,
+    );
+}
+
+#[test]
+fn test_expecting_message_internally_tagged_enum() {
+    #[derive(Deserialize)]
+    #[serde(tag = "tag")]
+    #[serde(expecting = "something strange...")]
+    enum Enum {
+        InternallyTagged,
+    }
+
+    assert_de_tokens_error::<Enum>(
+        &[Token::Str("InternallyTagged")],
+        r#"invalid type: string "InternallyTagged", expected something strange..."#,
+    );
+
+    // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
+    assert_de_tokens_error::<Enum>(
+        &[Token::Map { len: None }, Token::Str("tag"), Token::Unit],
+        r#"invalid type: unit value, expected variant identifier"#,
+    );
+}
+
+#[test]
+fn test_expecting_message_adjacently_tagged_enum() {
+    #[derive(Deserialize)]
+    #[serde(tag = "tag", content = "content")]
+    #[serde(expecting = "something strange...")]
+    enum Enum {
+        AdjacentlyTagged,
+    }
+
+    assert_de_tokens_error::<Enum>(
+        &[Token::Str("AdjacentlyTagged")],
+        r#"invalid type: string "AdjacentlyTagged", expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<Enum>(
+        &[Token::Map { len: None }, Token::Unit],
+        r#"invalid type: unit value, expected "tag", "content", or other ignored fields"#,
+    );
+
+    // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
+    assert_de_tokens_error::<Enum>(
+        &[Token::Map { len: None }, Token::Str("tag"), Token::Unit],
+        r#"invalid type: unit value, expected variant identifier"#,
+    );
+}
+
+#[test]
+fn test_expecting_message_untagged_tagged_enum() {
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    #[serde(expecting = "something strange...")]
+    enum Enum {
+        Untagged,
+    }
+
+    assert_de_tokens_error::<Enum>(&[Token::Str("Untagged")], r#"something strange..."#);
+}
+
+#[test]
+fn test_expecting_message_identifier_enum() {
+    #[derive(Deserialize)]
+    #[serde(field_identifier)]
+    #[serde(expecting = "something strange...")]
+    enum FieldEnum {
+        Field,
+    }
+
+    #[derive(Deserialize)]
+    #[serde(variant_identifier)]
+    #[serde(expecting = "something strange...")]
+    enum VariantEnum {
+        Variant,
+    }
+
+    assert_de_tokens_error::<FieldEnum>(
+        &[Token::Unit],
+        r#"invalid type: unit value, expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<FieldEnum>(
+        &[
+            Token::Enum { name: "FieldEnum" },
+            Token::Str("Unknown"),
+            Token::None,
+        ],
+        r#"invalid type: map, expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<VariantEnum>(
+        &[Token::Unit],
+        r#"invalid type: unit value, expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<VariantEnum>(
+        &[
+            Token::Enum {
+                name: "VariantEnum",
+            },
+            Token::Str("Unknown"),
+            Token::None,
+        ],
+        r#"invalid type: map, expected something strange..."#,
+    );
+}

test_suite/tests/test_borrow.rs

@@ -90,6 +90,30 @@ fn test_struct() {
     );
 }
 
+#[test]
+fn test_field_identifier() {
+    #[derive(Deserialize, Debug, PartialEq)]
+    #[serde(field_identifier)]
+    enum FieldStr<'a> {
+        #[serde(borrow)]
+        Str(&'a str),
+    }
+
+    assert_de_tokens(&FieldStr::Str("value"), &[Token::BorrowedStr("value")]);
+
+    #[derive(Deserialize, Debug, PartialEq)]
+    #[serde(field_identifier)]
+    enum FieldBytes<'a> {
+        #[serde(borrow)]
+        Bytes(&'a [u8]),
+    }
+
+    assert_de_tokens(
+        &FieldBytes::Bytes(b"value"),
+        &[Token::BorrowedBytes(b"value")],
+    );
+}
+
 #[test]
 fn test_cow() {
     #[derive(Deserialize)]

test_suite/tests/test_de.rs

@@ -622,6 +622,24 @@ declare_tests! {
                 Token::I32(2),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U8(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U16(0),
+                Token::I32(1),
+
+                Token::U16(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Map { len: Some(3) },
                 Token::U32(0),
@@ -631,6 +649,34 @@ declare_tests! {
                 Token::I32(2),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U64(0),
+                Token::I32(1),
+
+                Token::U64(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        // Mixed key types
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U64(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::Str("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Struct { name: "Struct", len: 2 },
                 Token::Str("a"),
@@ -647,6 +693,46 @@ declare_tests! {
             Token::SeqEnd,
         ],
     }
+    test_struct_borrowed_keys {
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::BorrowedStr("a"),
+                Token::I32(1),
+
+                Token::BorrowedStr("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Struct { name: "Struct", len: 2 },
+                Token::BorrowedStr("a"),
+                Token::I32(1),
+
+                Token::BorrowedStr("b"),
+                Token::I32(2),
+            Token::StructEnd,
+        ],
+    }
+    test_struct_owned_keys {
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::String("a"),
+                Token::I32(1),
+
+                Token::String("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Struct { name: "Struct", len: 2 },
+                Token::String("a"),
+                Token::I32(1),
+
+                Token::String("b"),
+                Token::I32(2),
+            Token::StructEnd,
+        ],
+    }
     test_struct_with_skip {
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Map { len: Some(3) },
@@ -663,6 +749,21 @@ declare_tests! {
                 Token::I32(4),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U16(1),
+                Token::I32(2),
+
+                Token::U32(2),
+                Token::I32(3),
+
+                Token::U64(3),
+                Token::I32(4),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Struct { name: "Struct", len: 2 },
                 Token::Str("a"),
@@ -780,6 +881,26 @@ declare_tests! {
             Token::Str("Unit"),
             Token::Unit,
         ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U8(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U16(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U32(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U64(0),
+            Token::Unit,
+        ],
     }
     test_enum_other {
         EnumOther::Other => &[
@@ -787,6 +908,26 @@ declare_tests! {
             Token::Str("Foo"),
             Token::Unit,
         ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U8(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U16(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U32(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U64(42),
+            Token::Unit,
+        ],
     }
     test_box {
         Box::new(0i32) => &[Token::I32(0)],
@@ -1452,4 +1593,25 @@ declare_error_tests! {
         ],
         "invalid value: integer `65536`, expected u16",
     }
+    test_duration_overflow_seq<Duration> {
+        &[
+            Token::Seq { len: Some(2) },
+                Token::U64(u64::max_value()),
+                Token::U32(1_000_000_000),
+            Token::SeqEnd,
+        ],
+        "overflow deserializing Duration",
+    }
+    test_duration_overflow_struct<Duration> {
+        &[
+            Token::Struct { name: "Duration", len: 2 },
+                Token::Str("secs"),
+                Token::U64(u64::max_value()),
+
+                Token::Str("nanos"),
+                Token::U32(1_000_000_000),
+            Token::StructEnd,
+        ],
+        "overflow deserializing Duration",
+    }
 }

test_suite/tests/test_identifier.rs

@@ -1,3 +1,4 @@
+//! Tests for `#[serde(field_identifier)]` and `#[serde(variant_identifier)]`
 use serde::Deserialize;
 use serde_test::{assert_de_tokens, Token};
 
@@ -27,6 +28,10 @@ fn test_field_identifier() {
         Bbb,
     }
 
+    assert_de_tokens(&F::Aaa, &[Token::U8(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U16(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U32(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U64(0)]);
     assert_de_tokens(&F::Aaa, &[Token::Str("aaa")]);
     assert_de_tokens(&F::Aaa, &[Token::Bytes(b"aaa")]);
 }
@@ -42,6 +47,10 @@ fn test_unit_fallthrough() {
         Other,
     }
 
+    assert_de_tokens(&F::Other, &[Token::U8(42)]);
+    assert_de_tokens(&F::Other, &[Token::U16(42)]);
+    assert_de_tokens(&F::Other, &[Token::U32(42)]);
+    assert_de_tokens(&F::Other, &[Token::U64(42)]);
     assert_de_tokens(&F::Other, &[Token::Str("x")]);
 }
 
@@ -68,5 +77,9 @@ fn test_newtype_fallthrough_generic() {
         Other(T),
     }
 
+    assert_de_tokens(&F::Other(42u8), &[Token::U8(42)]);
+    assert_de_tokens(&F::Other(42u16), &[Token::U16(42)]);
+    assert_de_tokens(&F::Other(42u32), &[Token::U32(42)]);
+    assert_de_tokens(&F::Other(42u64), &[Token::U64(42)]);
     assert_de_tokens(&F::Other("x".to_owned()), &[Token::Str("x")]);
 }

test_suite/tests/ui/rename/container_unknown_rename_rule.stderr

@@ -1,4 +1,4 @@
-error: unknown rename rule for #[serde(rename_all = "abc")]
+error: unknown rename rule `rename_all = "abc"`, expected one of "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE", "kebab-case", "SCREAMING-KEBAB-CASE"
  --> $DIR/container_unknown_rename_rule.rs:4:22
   |
 4 | #[serde(rename_all = "abc")]

test_suite/tests/ui/rename/variant_unknown_rename_rule.stderr

@@ -1,4 +1,4 @@
-error: unknown rename rule for #[serde(rename_all = "abc")]
+error: unknown rename rule `rename_all = "abc"`, expected one of "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE", "kebab-case", "SCREAMING-KEBAB-CASE"
  --> $DIR/variant_unknown_rename_rule.rs:5:26
   |
 5 |     #[serde(rename_all = "abc")]