Release 1.0.183

Refactor code that generates `__Field` enums

.github/workflows/ci.yml

@@ -77,7 +77,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.19.0, 1.20.0, 1.21.0, 1.25.0, 1.26.0, 1.34.0]
+        rust: [1.31.0, 1.34.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v3
@@ -88,24 +88,6 @@ jobs:
       - run: cd serde && cargo build --no-default-features
       - run: cd serde && cargo build
 
-  more:
-    name: Rust ${{matrix.rust}}
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        rust: [1.27.0, 1.28.0]
-    timeout-minutes: 45
-    steps:
-      - uses: actions/checkout@v3
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: ${{matrix.rust}}
-        # Work around failing to parse manifest because editions are unstable.
-      - run: sed -i /test_suite/d Cargo.toml
-      - run: cd serde && cargo build --no-default-features
-      - run: cd serde && cargo build
-
   derive:
     name: Rust 1.56.0
     runs-on: ubuntu-latest
@@ -127,6 +109,29 @@ jobs:
       - uses: dtolnay/rust-toolchain@1.36.0
       - run: cd serde && cargo build --no-default-features --features alloc
 
+  precompiled:
+    name: Precompiled
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@nightly
+        with:
+          components: rust-src
+          targets: x86_64-unknown-linux-musl
+      - run: precompiled/build.sh
+      - name: replace serde_derive dependency with precompiled
+        run: |
+          # FIXME: consider using `cargo rm serde_derive` but it's currently broken
+          # https://github.com/rust-lang/cargo/issues/12419
+          sed -i '/serde_derive =/d' serde/Cargo.toml
+          sed -i '/derive = \["serde_derive"\]/d' serde/Cargo.toml
+          sed -i '/"serde_derive"/d' Cargo.toml
+          sed -i '/\[workspace\]/d' precompiled/serde_derive/Cargo.toml
+          cargo add --dev serde_derive --path precompiled/serde_derive --manifest-path test_suite/Cargo.toml
+          git diff
+      - run: cd test_suite && cargo test --features unstable -- --skip ui --exact
+
   macos:
     name: macOS
     runs-on: macos-latest

README.md

@@ -1,12 +1,12 @@
-# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.19+]][Rust 1.19] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.31+]][Rust 1.31] [![serde_derive: rustc 1.56+]][Rust 1.56]
 
 [Build Status]: https://img.shields.io/github/actions/workflow/status/serde-rs/serde/ci.yml?branch=master
 [actions]: https://github.com/serde-rs/serde/actions?query=branch%3Amaster
 [Latest Version]: https://img.shields.io/crates/v/serde.svg
 [crates.io]: https://crates.io/crates/serde
-[serde: rustc 1.19+]: https://img.shields.io/badge/serde-rustc_1.19+-lightgray.svg
+[serde: rustc 1.31+]: https://img.shields.io/badge/serde-rustc_1.31+-lightgray.svg
 [serde_derive: rustc 1.56+]: https://img.shields.io/badge/serde_derive-rustc_1.56+-lightgray.svg
-[Rust 1.19]: https://blog.rust-lang.org/2017/07/20/Rust-1.19.html
+[Rust 1.31]: https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html
 [Rust 1.56]: https://blog.rust-lang.org/2021/10/21/Rust-1.56.0.html
 
 **Serde is a framework for *ser*ializing and *de*serializing Rust data structures efficiently and generically.**

precompiled/bin/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.178"
+version = "1.0.183"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 publish = false
 
@@ -14,4 +14,4 @@ path = "main.rs"
 [dependencies]
 proc-macro2 = "1"
 quote = { version = "1", default-features = false }
-syn = { version = "2.0.25", default-features = false, features = ["clone-impls", "derive", "full", "parsing", "printing"] }
+syn = { version = "2.0.28", default-features = false, features = ["clone-impls", "derive", "full", "parsing", "printing"] }

precompiled/serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.178"
+version = "1.0.183"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 categories = ["no-std", "no-std::no-alloc"]
 description = "Implementation of #[derive(Serialize, Deserialize)]"
@@ -24,7 +24,7 @@ proc-macro = true
 [target.'cfg(not(all(target_arch = "x86_64", target_os = "linux", target_env = "gnu")))'.dependencies]
 proc-macro2 = "1"
 quote = "1"
-syn = "2.0.25"
+syn = "2.0.28"
 
 [dev-dependencies]
 serde = { version = "1", path = "../../serde" }

precompiled/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/1.0.178")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.183")]
 
 #[cfg(not(all(target_arch = "x86_64", target_os = "linux", target_env = "gnu")))]
 include!("lib_from_source.rs");

serde/Cargo.toml

@@ -1,20 +1,21 @@
 [package]
 name = "serde"
-version = "1.0.178" # remember to update html_root_url and serde_derive dependency
+version = "1.0.183" # remember to update html_root_url and serde_derive dependency
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 build = "build.rs"
 categories = ["encoding", "no-std", "no-std::no-alloc"]
 description = "A generic serialization/deserialization framework"
 documentation = "https://docs.rs/serde"
+edition = "2018"
 homepage = "https://serde.rs"
 keywords = ["serde", "serialization", "no_std"]
 license = "MIT OR Apache-2.0"
 readme = "crates-io.md"
 repository = "https://github.com/serde-rs/serde"
-rust-version = "1.19"
+rust-version = "1.31"
 
 [dependencies]
-serde_derive = { version = "=1.0.178", optional = true, path = "../serde_derive" }
+serde_derive = { version = "=1.0.183", optional = true, path = "../serde_derive" }
 
 [dev-dependencies]
 serde_derive = { version = "1", path = "../serde_derive" }

serde/build.rs

@@ -16,68 +16,6 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // std::collections::Bound was stabilized in Rust 1.17
-    // but it was moved to core::ops later in Rust 1.26:
-    // https://doc.rust-lang.org/core/ops/enum.Bound.html
-    if minor < 26 {
-        println!("cargo:rustc-cfg=no_ops_bound");
-        if minor < 17 {
-            println!("cargo:rustc-cfg=no_collections_bound");
-        }
-    }
-
-    // core::cmp::Reverse stabilized in Rust 1.19:
-    // https://doc.rust-lang.org/stable/core/cmp/struct.Reverse.html
-    if minor < 19 {
-        println!("cargo:rustc-cfg=no_core_reverse");
-    }
-
-    // CString::into_boxed_c_str and PathBuf::into_boxed_path stabilized in Rust 1.20:
-    // https://doc.rust-lang.org/std/ffi/struct.CString.html#method.into_boxed_c_str
-    // https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.into_boxed_path
-    if minor < 20 {
-        println!("cargo:rustc-cfg=no_de_boxed_c_str");
-        println!("cargo:rustc-cfg=no_de_boxed_path");
-    }
-
-    // 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=no_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=no_core_duration");
-    }
-
-    // 128-bit integers stabilized in Rust 1.26:
-    // https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
-    //
-    // Disabled on Emscripten targets before Rust 1.40 since
-    // Emscripten did not support 128-bit integers until Rust 1.40
-    // (https://github.com/rust-lang/rust/pull/65251)
-    if minor < 26 || emscripten && minor < 40 {
-        println!("cargo:rustc-cfg=no_integer128");
-    }
-
-    // Inclusive ranges methods stabilized in Rust 1.27:
-    // https://github.com/rust-lang/rust/pull/50758
-    // Also Iterator::try_for_each:
-    // https://blog.rust-lang.org/2018/06/21/Rust-1.27.html#library-stabilizations
-    if minor < 27 {
-        println!("cargo:rustc-cfg=no_range_inclusive");
-        println!("cargo:rustc-cfg=no_iterator_try_fold");
-    }
-
-    // Non-zero integers stabilized in Rust 1.28:
-    // https://blog.rust-lang.org/2018/08/02/Rust-1.28.html#library-stabilizations
-    if minor < 28 {
-        println!("cargo:rustc-cfg=no_num_nonzero");
-    }
-
     // TryFrom, Atomic types, non-zero signed integers, and SystemTime::checked_add
     // stabilized in Rust 1.34:
     // https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html#tryfrom-and-tryinto
@@ -89,6 +27,13 @@ fn main() {
         println!("cargo:rustc-cfg=no_relaxed_trait_bounds");
     }
 
+    // Disabled on Emscripten targets before Rust 1.40 since
+    // Emscripten did not support 128-bit integers until Rust 1.40
+    // (https://github.com/rust-lang/rust/pull/65251)
+    if emscripten && minor < 40 {
+        println!("cargo:rustc-cfg=no_integer128");
+    }
+
     // Current minimum supported version of serde_derive crate is Rust 1.56.
     if minor < 56 {
         println!("cargo:rustc-cfg=no_serde_derive");

serde/src/de/format.rs

@@ -1,5 +1,5 @@
-use lib::fmt::{self, Write};
+use crate::lib::fmt::{self, Write};
-use lib::str;
+use crate::lib::str;
 
 pub(super) struct Buf<'a> {
     bytes: &'a mut [u8],

serde/src/de/ignored_any.rs

@@ -1,6 +1,6 @@
-use lib::*;
+use crate::lib::*;
 
-use de::{
+use crate::de::{
     Deserialize, Deserializer, EnumAccess, Error, MapAccess, SeqAccess, VariantAccess, Visitor,
 };
 
@@ -197,7 +197,7 @@ impl<'de> Visitor<'de> for IgnoredAny {
     where
         A: SeqAccess<'de>,
     {
-        while let Some(IgnoredAny) = try!(seq.next_element()) {
+        while let Some(IgnoredAny) = tri!(seq.next_element()) {
             // Gobble
         }
         Ok(IgnoredAny)
@@ -208,7 +208,7 @@ impl<'de> Visitor<'de> for IgnoredAny {
     where
         A: MapAccess<'de>,
     {
-        while let Some((IgnoredAny, IgnoredAny)) = try!(map.next_entry()) {
+        while let Some((IgnoredAny, IgnoredAny)) = tri!(map.next_entry()) {
             // Gobble
         }
         Ok(IgnoredAny)
@@ -227,7 +227,7 @@ impl<'de> Visitor<'de> for IgnoredAny {
     where
         A: EnumAccess<'de>,
     {
-        try!(data.variant::<IgnoredAny>()).1.newtype_variant()
+        tri!(data.variant::<IgnoredAny>()).1.newtype_variant()
     }
 }
 

serde/src/de/impls.rs

@@ -1,16 +1,14 @@
-use lib::*;
+use crate::lib::*;
 
-use de::{
+use crate::de::{
-    Deserialize, Deserializer, EnumAccess, Error, SeqAccess, Unexpected, VariantAccess, Visitor,
+    Deserialize, Deserializer, EnumAccess, Error, MapAccess, SeqAccess, Unexpected, VariantAccess,
+    Visitor,
 };
 
-#[cfg(any(feature = "std", feature = "alloc", not(no_core_duration)))]
+use crate::seed::InPlaceSeed;
-use de::MapAccess;
-
-use seed::InPlaceSeed;
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-use __private::size_hint;
+use crate::de::size_hint;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -84,7 +82,7 @@ macro_rules! impl_deserialize_num {
     ($primitive:ident, $nonzero:ident $(cfg($($cfg:tt)*))*, $deserialize:ident $($method:ident!($($val:ident : $visit:ident)*);)*) => {
         impl_deserialize_num!($primitive, $deserialize $($method!($($val : $visit)*);)*);
 
-        #[cfg(all(not(no_num_nonzero), $($($cfg)*)*))]
+        $(#[cfg($($cfg)*)])*
         impl<'de> Deserialize<'de> for num::$nonzero {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
@@ -684,7 +682,7 @@ impl<'de> Visitor<'de> for CStringVisitor {
         let capacity = size_hint::cautious::<u8>(seq.size_hint());
         let mut values = Vec::<u8>::with_capacity(capacity);
 
-        while let Some(value) = try!(seq.next_element()) {
+        while let Some(value) = tri!(seq.next_element()) {
             values.push(value);
         }
 
@@ -747,13 +745,9 @@ macro_rules! forwarded_impl {
     }
 }
 
-#[cfg(all(
+#[cfg(any(feature = "std", all(not(no_core_cstr), feature = "alloc")))]
-    any(feature = "std", all(not(no_core_cstr), feature = "alloc")),
-    not(no_de_boxed_c_str)
-))]
 forwarded_impl!((), Box<CStr>, CString::into_boxed_c_str);
 
-#[cfg(not(no_core_reverse))]
 forwarded_impl!((T), Reverse<T>, Reverse);
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -901,7 +895,7 @@ macro_rules! seq_impl {
                     {
                         let mut values = $with_capacity;
 
-                        while let Some(value) = try!($access.next_element()) {
+                        while let Some(value) = tri!($access.next_element()) {
                             $insert(&mut values, value);
                         }
 
@@ -939,7 +933,7 @@ macro_rules! seq_impl {
                         $reserve(&mut self.0, size_hint::cautious::<T>($access.size_hint()));
 
                         // FIXME: try to overwrite old values here? (Vec, VecDeque, LinkedList)
-                        while let Some(value) = try!($access.next_element()) {
+                        while let Some(value) = tri!($access.next_element()) {
                             $insert(&mut self.0, value);
                         }
 
@@ -1039,7 +1033,7 @@ where
                 let capacity = size_hint::cautious::<T>(seq.size_hint());
                 let mut values = Vec::<T>::with_capacity(capacity);
 
-                while let Some(value) = try!(seq.next_element()) {
+                while let Some(value) = tri!(seq.next_element()) {
                     values.push(value);
                 }
 
@@ -1081,7 +1075,7 @@ where
                 for i in 0..self.0.len() {
                     let next = {
                         let next_place = InPlaceSeed(&mut self.0[i]);
-                        try!(seq.next_element_seed(next_place))
+                        tri!(seq.next_element_seed(next_place))
                     };
                     if next.is_none() {
                         self.0.truncate(i);
@@ -1089,7 +1083,7 @@ where
                     }
                 }
 
-                while let Some(value) = try!(seq.next_element()) {
+                while let Some(value) = tri!(seq.next_element()) {
                     self.0.push(value);
                 }
 
@@ -1161,7 +1155,7 @@ macro_rules! array_impls {
                     A: SeqAccess<'de>,
                 {
                     Ok([$(
-                        match try!(seq.next_element()) {
+                        match tri!(seq.next_element()) {
                             Some(val) => val,
                             None => return Err(Error::invalid_length($n, &self)),
                         }
@@ -1186,7 +1180,7 @@ macro_rules! array_impls {
                 {
                     let mut fail_idx = None;
                     for (idx, dest) in self.0[..].iter_mut().enumerate() {
-                        if try!(seq.next_element_seed(InPlaceSeed(dest))).is_none() {
+                        if tri!(seq.next_element_seed(InPlaceSeed(dest))).is_none() {
                             fail_idx = Some(idx);
                             break;
                         }
@@ -1284,7 +1278,7 @@ macro_rules! tuple_impls {
                             A: SeqAccess<'de>,
                         {
                             $(
-                                let $name = match try!(seq.next_element()) {
+                                let $name = match tri!(seq.next_element()) {
                                     Some(value) => value,
                                     None => return Err(Error::invalid_length($n, &self)),
                                 };
@@ -1318,7 +1312,7 @@ macro_rules! tuple_impls {
                             A: SeqAccess<'de>,
                         {
                             $(
-                                if try!(seq.next_element_seed(InPlaceSeed(&mut (self.0).$n))).is_none() {
+                                if tri!(seq.next_element_seed(InPlaceSeed(&mut (self.0).$n))).is_none() {
                                     return Err(Error::invalid_length($n, &self));
                                 }
                             )+
@@ -1395,7 +1389,7 @@ macro_rules! map_impl {
                     {
                         let mut values = $with_capacity;
 
-                        while let Some((key, value)) = try!($access.next_entry()) {
+                        while let Some((key, value)) = tri!($access.next_entry()) {
                             values.insert(key, value);
                         }
 
@@ -1541,7 +1535,7 @@ macro_rules! deserialize_enum {
             where
                 A: EnumAccess<'de>,
             {
-                match try!(data.variant()) {
+                match tri!(data.variant()) {
                     $(
                         ($name_kind :: $variant, v) => v.newtype_variant().map($name :: $variant),
                     )*
@@ -1561,7 +1555,7 @@ impl<'de> Deserialize<'de> for net::IpAddr {
         if deserializer.is_human_readable() {
             deserializer.deserialize_str(FromStrVisitor::new("IP address"))
         } else {
-            use lib::net::IpAddr;
+            use crate::lib::net::IpAddr;
             deserialize_enum! {
                 IpAddr IpAddrKind (V4; b"V4"; 0, V6; b"V6"; 1)
                 "`V4` or `V6`",
@@ -1604,7 +1598,7 @@ impl<'de> Deserialize<'de> for net::SocketAddr {
         if deserializer.is_human_readable() {
             deserializer.deserialize_str(FromStrVisitor::new("socket address"))
         } else {
-            use lib::net::SocketAddr;
+            use crate::lib::net::SocketAddr;
             deserialize_enum! {
                 SocketAddr SocketAddrKind (V4; b"V4"; 0, V6; b"V6"; 1)
                 "`V4` or `V6`",
@@ -1714,7 +1708,7 @@ impl<'de> Deserialize<'de> for PathBuf {
     }
 }
 
-#[cfg(all(feature = "std", not(no_de_boxed_path)))]
+#[cfg(feature = "std")]
 forwarded_impl!((), Box<Path>, PathBuf::into_boxed_path);
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -1748,7 +1742,7 @@ impl<'de> Visitor<'de> for OsStringVisitor {
     {
         use std::os::unix::ffi::OsStringExt;
 
-        match try!(data.variant()) {
+        match tri!(data.variant()) {
             (OsStringKind::Unix, v) => v.newtype_variant().map(OsString::from_vec),
             (OsStringKind::Windows, _) => Err(Error::custom(
                 "cannot deserialize Windows OS string on Unix",
@@ -1763,7 +1757,7 @@ impl<'de> Visitor<'de> for OsStringVisitor {
     {
         use std::os::windows::ffi::OsStringExt;
 
-        match try!(data.variant()) {
+        match tri!(data.variant()) {
             (OsStringKind::Windows, v) => v
                 .newtype_variant::<Vec<u16>>()
                 .map(|vec| OsString::from_wide(&vec)),
@@ -1795,29 +1789,8 @@ 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(no_de_rc_dst, feature = "rc", any(feature = "std", feature = "alloc")))]
+#[cfg(all(feature = "std", any(unix, windows)))]
-forwarded_impl! {
+forwarded_impl!((), Box<OsStr>, OsString::into_boxed_os_str);
-    /// This impl requires the [`"rc"`] Cargo feature of Serde.
-    ///
-    /// Deserializing a data structure containing `Arc` will not attempt to
-    /// deduplicate `Arc` references to the same data. Every deserialized `Arc`
-    /// will end up with a strong count of 1.
-    ///
-    /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
-    (T), Arc<T>, Arc::new
-}
-
-#[cfg(all(no_de_rc_dst, feature = "rc", any(feature = "std", feature = "alloc")))]
-forwarded_impl! {
-    /// This impl requires the [`"rc"`] Cargo feature of Serde.
-    ///
-    /// Deserializing a data structure containing `Rc` will not attempt to
-    /// deduplicate `Rc` references to the same data. Every deserialized `Rc`
-    /// will end up with a strong count of 1.
-    ///
-    /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
-    (T), Rc<T>, Rc::new
-}
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'de, 'a, T: ?Sized> Deserialize<'de> for Cow<'a, T>
@@ -1849,7 +1822,7 @@ where
     where
         D: Deserializer<'de>,
     {
-        try!(Option::<T>::deserialize(deserializer));
+        tri!(Option::<T>::deserialize(deserializer));
         Ok(RcWeak::new())
     }
 }
@@ -1867,18 +1840,14 @@ where
     where
         D: Deserializer<'de>,
     {
-        try!(Option::<T>::deserialize(deserializer));
+        tri!(Option::<T>::deserialize(deserializer));
         Ok(ArcWeak::new())
     }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(all(
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
-    not(no_de_rc_dst),
-    feature = "rc",
-    any(feature = "std", feature = "alloc")
-))]
 macro_rules! box_forwarded_impl {
     (
         $(#[doc = $doc:tt])*
@@ -1899,11 +1868,7 @@ macro_rules! box_forwarded_impl {
     };
 }
 
-#[cfg(all(
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
-    not(no_de_rc_dst),
-    feature = "rc",
-    any(feature = "std", feature = "alloc")
-))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1915,11 +1880,7 @@ box_forwarded_impl! {
     Rc
 }
 
-#[cfg(all(
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
-    not(no_de_rc_dst),
-    feature = "rc",
-    any(feature = "std", feature = "alloc")
-))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1963,7 +1924,6 @@ forwarded_impl!((T), RwLock<T>, RwLock::new);
 //         secs: u64,
 //         nanos: u32,
 //     }
-#[cfg(any(feature = "std", not(no_core_duration)))]
 impl<'de> Deserialize<'de> for Duration {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -2011,7 +1971,7 @@ impl<'de> Deserialize<'de> for Duration {
                             b"secs" => Ok(Field::Secs),
                             b"nanos" => Ok(Field::Nanos),
                             _ => {
-                                let value = ::__private::from_utf8_lossy(value);
+                                let value = crate::__private::from_utf8_lossy(value);
                                 Err(Error::unknown_field(&*value, FIELDS))
                             }
                         }
@@ -2046,19 +2006,19 @@ impl<'de> Deserialize<'de> for Duration {
             where
                 A: SeqAccess<'de>,
             {
-                let secs: u64 = match try!(seq.next_element()) {
+                let secs: u64 = match tri!(seq.next_element()) {
                     Some(value) => value,
                     None => {
                         return Err(Error::invalid_length(0, &self));
                     }
                 };
-                let nanos: u32 = match try!(seq.next_element()) {
+                let nanos: u32 = match tri!(seq.next_element()) {
                     Some(value) => value,
                     None => {
                         return Err(Error::invalid_length(1, &self));
                     }
                 };
-                try!(check_overflow(secs, nanos));
+                tri!(check_overflow(secs, nanos));
                 Ok(Duration::new(secs, nanos))
             }
 
@@ -2068,19 +2028,19 @@ impl<'de> Deserialize<'de> for Duration {
             {
                 let mut secs: Option<u64> = None;
                 let mut nanos: Option<u32> = None;
-                while let Some(key) = try!(map.next_key()) {
+                while let Some(key) = tri!(map.next_key()) {
                     match key {
                         Field::Secs => {
                             if secs.is_some() {
                                 return Err(<A::Error as Error>::duplicate_field("secs"));
                             }
-                            secs = Some(try!(map.next_value()));
+                            secs = Some(tri!(map.next_value()));
                         }
                         Field::Nanos => {
                             if nanos.is_some() {
                                 return Err(<A::Error as Error>::duplicate_field("nanos"));
                             }
-                            nanos = Some(try!(map.next_value()));
+                            nanos = Some(tri!(map.next_value()));
                         }
                     }
                 }
@@ -2092,7 +2052,7 @@ impl<'de> Deserialize<'de> for Duration {
                     Some(nanos) => nanos,
                     None => return Err(<A::Error as Error>::missing_field("nanos")),
                 };
-                try!(check_overflow(secs, nanos));
+                tri!(check_overflow(secs, nanos));
                 Ok(Duration::new(secs, nanos))
             }
         }
@@ -2184,19 +2144,19 @@ impl<'de> Deserialize<'de> for SystemTime {
             where
                 A: SeqAccess<'de>,
             {
-                let secs: u64 = match try!(seq.next_element()) {
+                let secs: u64 = match tri!(seq.next_element()) {
                     Some(value) => value,
                     None => {
                         return Err(Error::invalid_length(0, &self));
                     }
                 };
-                let nanos: u32 = match try!(seq.next_element()) {
+                let nanos: u32 = match tri!(seq.next_element()) {
                     Some(value) => value,
                     None => {
                         return Err(Error::invalid_length(1, &self));
                     }
                 };
-                try!(check_overflow(secs, nanos));
+                tri!(check_overflow(secs, nanos));
                 Ok(Duration::new(secs, nanos))
             }
 
@@ -2206,7 +2166,7 @@ impl<'de> Deserialize<'de> for SystemTime {
             {
                 let mut secs: Option<u64> = None;
                 let mut nanos: Option<u32> = None;
-                while let Some(key) = try!(map.next_key()) {
+                while let Some(key) = tri!(map.next_key()) {
                     match key {
                         Field::Secs => {
                             if secs.is_some() {
@@ -2214,7 +2174,7 @@ impl<'de> Deserialize<'de> for SystemTime {
                                     "secs_since_epoch",
                                 ));
                             }
-                            secs = Some(try!(map.next_value()));
+                            secs = Some(tri!(map.next_value()));
                         }
                         Field::Nanos => {
                             if nanos.is_some() {
@@ -2222,7 +2182,7 @@ impl<'de> Deserialize<'de> for SystemTime {
                                     "nanos_since_epoch",
                                 ));
                             }
-                            nanos = Some(try!(map.next_value()));
+                            nanos = Some(tri!(map.next_value()));
                         }
                     }
                 }
@@ -2234,13 +2194,13 @@ impl<'de> Deserialize<'de> for SystemTime {
                     Some(nanos) => nanos,
                     None => return Err(<A::Error as Error>::missing_field("nanos_since_epoch")),
                 };
-                try!(check_overflow(secs, nanos));
+                tri!(check_overflow(secs, nanos));
                 Ok(Duration::new(secs, nanos))
             }
         }
 
         const FIELDS: &[&str] = &["secs_since_epoch", "nanos_since_epoch"];
-        let duration = try!(deserializer.deserialize_struct("SystemTime", FIELDS, DurationVisitor));
+        let duration = tri!(deserializer.deserialize_struct("SystemTime", FIELDS, DurationVisitor));
         #[cfg(not(no_systemtime_checked_add))]
         let ret = UNIX_EPOCH
             .checked_add(duration)
@@ -2269,7 +2229,7 @@ where
     where
         D: Deserializer<'de>,
     {
-        let (start, end) = try!(deserializer.deserialize_struct(
+        let (start, end) = tri!(deserializer.deserialize_struct(
             "Range",
             range::FIELDS,
             range::RangeVisitor {
@@ -2281,7 +2241,6 @@ where
     }
 }
 
-#[cfg(not(no_range_inclusive))]
 impl<'de, Idx> Deserialize<'de> for RangeInclusive<Idx>
 where
     Idx: Deserialize<'de>,
@@ -2290,7 +2249,7 @@ where
     where
         D: Deserializer<'de>,
     {
-        let (start, end) = try!(deserializer.deserialize_struct(
+        let (start, end) = tri!(deserializer.deserialize_struct(
             "RangeInclusive",
             range::FIELDS,
             range::RangeVisitor {
@@ -2303,9 +2262,9 @@ where
 }
 
 mod range {
-    use lib::*;
+    use crate::lib::*;
 
-    use de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
+    use crate::de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
 
     pub const FIELDS: &[&str] = &["start", "end"];
 
@@ -2351,7 +2310,7 @@ mod range {
                         b"start" => Ok(Field::Start),
                         b"end" => Ok(Field::End),
                         _ => {
-                            let value = ::__private::from_utf8_lossy(value);
+                            let value = crate::__private::from_utf8_lossy(value);
                             Err(Error::unknown_field(&*value, FIELDS))
                         }
                     }
@@ -2381,13 +2340,13 @@ mod range {
         where
             A: SeqAccess<'de>,
         {
-            let start: Idx = match try!(seq.next_element()) {
+            let start: Idx = match tri!(seq.next_element()) {
                 Some(value) => value,
                 None => {
                     return Err(Error::invalid_length(0, &self));
                 }
             };
-            let end: Idx = match try!(seq.next_element()) {
+            let end: Idx = match tri!(seq.next_element()) {
                 Some(value) => value,
                 None => {
                     return Err(Error::invalid_length(1, &self));
@@ -2402,19 +2361,19 @@ mod range {
         {
             let mut start: Option<Idx> = None;
             let mut end: Option<Idx> = None;
-            while let Some(key) = try!(map.next_key()) {
+            while let Some(key) = tri!(map.next_key()) {
                 match key {
                     Field::Start => {
                         if start.is_some() {
                             return Err(<A::Error as Error>::duplicate_field("start"));
                         }
-                        start = Some(try!(map.next_value()));
+                        start = Some(tri!(map.next_value()));
                     }
                     Field::End => {
                         if end.is_some() {
                             return Err(<A::Error as Error>::duplicate_field("end"));
                         }
-                        end = Some(try!(map.next_value()));
+                        end = Some(tri!(map.next_value()));
                     }
                 }
             }
@@ -2448,7 +2407,7 @@ where
     where
         D: Deserializer<'de>,
     {
-        let start = try!(deserializer.deserialize_struct(
+        let start = tri!(deserializer.deserialize_struct(
             "RangeFrom",
             range_from::FIELDS,
             range_from::RangeFromVisitor {
@@ -2461,9 +2420,9 @@ where
 }
 
 mod range_from {
-    use lib::*;
+    use crate::lib::*;
 
-    use de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
+    use crate::de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
 
     pub const FIELDS: &[&str] = &["end"];
 
@@ -2506,7 +2465,7 @@ mod range_from {
                     match value {
                         b"end" => Ok(Field::End),
                         _ => {
-                            let value = ::__private::from_utf8_lossy(value);
+                            let value = crate::__private::from_utf8_lossy(value);
                             Err(Error::unknown_field(&*value, FIELDS))
                         }
                     }
@@ -2536,7 +2495,7 @@ mod range_from {
         where
             A: SeqAccess<'de>,
         {
-            let end: Idx = match try!(seq.next_element()) {
+            let end: Idx = match tri!(seq.next_element()) {
                 Some(value) => value,
                 None => {
                     return Err(Error::invalid_length(0, &self));
@@ -2550,13 +2509,13 @@ mod range_from {
             A: MapAccess<'de>,
         {
             let mut end: Option<Idx> = None;
-            while let Some(key) = try!(map.next_key()) {
+            while let Some(key) = tri!(map.next_key()) {
                 match key {
                     Field::End => {
                         if end.is_some() {
                             return Err(<A::Error as Error>::duplicate_field("end"));
                         }
-                        end = Some(try!(map.next_value()));
+                        end = Some(tri!(map.next_value()));
                     }
                 }
             }
@@ -2586,7 +2545,7 @@ where
     where
         D: Deserializer<'de>,
     {
-        let end = try!(deserializer.deserialize_struct(
+        let end = tri!(deserializer.deserialize_struct(
             "RangeTo",
             range_to::FIELDS,
             range_to::RangeToVisitor {
@@ -2599,9 +2558,9 @@ where
 }
 
 mod range_to {
-    use lib::*;
+    use crate::lib::*;
 
-    use de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
+    use crate::de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
 
     pub const FIELDS: &[&str] = &["start"];
 
@@ -2644,7 +2603,7 @@ mod range_to {
                     match value {
                         b"start" => Ok(Field::Start),
                         _ => {
-                            let value = ::__private::from_utf8_lossy(value);
+                            let value = crate::__private::from_utf8_lossy(value);
                             Err(Error::unknown_field(&*value, FIELDS))
                         }
                     }
@@ -2674,7 +2633,7 @@ mod range_to {
         where
             A: SeqAccess<'de>,
         {
-            let start: Idx = match try!(seq.next_element()) {
+            let start: Idx = match tri!(seq.next_element()) {
                 Some(value) => value,
                 None => {
                     return Err(Error::invalid_length(0, &self));
@@ -2688,13 +2647,13 @@ mod range_to {
             A: MapAccess<'de>,
         {
             let mut start: Option<Idx> = None;
-            while let Some(key) = try!(map.next_key()) {
+            while let Some(key) = tri!(map.next_key()) {
                 match key {
                     Field::Start => {
                         if start.is_some() {
                             return Err(<A::Error as Error>::duplicate_field("start"));
                         }
-                        start = Some(try!(map.next_value()));
+                        start = Some(tri!(map.next_value()));
                     }
                 }
             }
@@ -2709,7 +2668,6 @@ mod range_to {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(not(no_ops_bound), all(feature = "std", not(no_collections_bound))))]
 impl<'de, T> Deserialize<'de> for Bound<T>
 where
     T: Deserialize<'de>,
@@ -2801,7 +2759,7 @@ where
             where
                 A: EnumAccess<'de>,
             {
-                match try!(data.variant()) {
+                match tri!(data.variant()) {
                     (Field::Unbounded, v) => v.unit_variant().map(|()| Bound::Unbounded),
                     (Field::Included, v) => v.newtype_variant().map(Bound::Included),
                     (Field::Excluded, v) => v.newtype_variant().map(Bound::Excluded),
@@ -2910,7 +2868,7 @@ where
             where
                 A: EnumAccess<'de>,
             {
-                match try!(data.variant()) {
+                match tri!(data.variant()) {
                     (Field::Ok, v) => v.newtype_variant().map(Ok),
                     (Field::Err, v) => v.newtype_variant().map(Err),
                 }

serde/src/de/mod.rs

@@ -112,7 +112,7 @@
 //! [derive section of the manual]: https://serde.rs/derive.html
 //! [data formats]: https://serde.rs/#data-formats
 
-use lib::*;
+use crate::lib::*;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -122,19 +122,20 @@ pub mod value;
 mod format;
 mod ignored_any;
 mod impls;
+pub(crate) mod size_hint;
 mod utf8;
 
 pub use self::ignored_any::IgnoredAny;
 
+#[cfg(not(any(feature = "std", feature = "unstable")))]
+#[doc(no_inline)]
+pub use crate::std_error::Error as StdError;
 #[cfg(all(feature = "unstable", not(feature = "std")))]
 #[doc(no_inline)]
 pub use core::error::Error as StdError;
 #[cfg(feature = "std")]
 #[doc(no_inline)]
 pub use std::error::Error as StdError;
-#[cfg(not(any(feature = "std", feature = "unstable")))]
-#[doc(no_inline)]
-pub use std_error::Error as StdError;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -569,7 +570,7 @@ pub trait Deserialize<'de>: Sized {
         D: Deserializer<'de>,
     {
         // Default implementation just delegates to `deserialize` impl.
-        *place = try!(Deserialize::deserialize(deserializer));
+        *place = tri!(Deserialize::deserialize(deserializer));
         Ok(())
     }
 }
@@ -1229,11 +1230,11 @@ pub trait Deserializer<'de>: Sized {
     #[doc(hidden)]
     fn __deserialize_content<V>(
         self,
-        _: ::actually_private::T,
+        _: crate::actually_private::T,
         visitor: V,
-    ) -> Result<::private::de::Content<'de>, Self::Error>
+    ) -> Result<crate::__private::de::Content<'de>, Self::Error>
     where
-        V: Visitor<'de, Value = ::private::de::Content<'de>>,
+        V: Visitor<'de, Value = crate::__private::de::Content<'de>>,
     {
         self.deserialize_any(visitor)
     }
@@ -1834,9 +1835,9 @@ pub trait MapAccess<'de> {
         K: DeserializeSeed<'de>,
         V: DeserializeSeed<'de>,
     {
-        match try!(self.next_key_seed(kseed)) {
+        match tri!(self.next_key_seed(kseed)) {
             Some(key) => {
-                let value = try!(self.next_value_seed(vseed));
+                let value = tri!(self.next_value_seed(vseed));
                 Ok(Some((key, value)))
             }
             None => Ok(None),
@@ -2284,12 +2285,12 @@ impl Display for OneOf {
             1 => write!(formatter, "`{}`", self.names[0]),
             2 => write!(formatter, "`{}` or `{}`", self.names[0], self.names[1]),
             _ => {
-                try!(write!(formatter, "one of "));
+                tri!(write!(formatter, "one of "));
                 for (i, alt) in self.names.iter().enumerate() {
                     if i > 0 {
-                        try!(write!(formatter, ", "));
+                        tri!(write!(formatter, ", "));
                     }
-                    try!(write!(formatter, "`{}`", alt));
+                    tri!(write!(formatter, "`{}`", alt));
                 }
                 Ok(())
             }

serde/src/de/seed.rs

@@ -1,4 +1,4 @@
-use de::{Deserialize, DeserializeSeed, Deserializer};
+use crate::de::{Deserialize, DeserializeSeed, Deserializer};
 
 /// A DeserializeSeed helper for implementing deserialize_in_place Visitors.
 ///

serde/src/de/size_hint.rs

@@ -1,4 +1,4 @@
-use lib::*;
+use crate::lib::*;
 
 pub fn from_bounds<I>(iter: &I) -> Option<usize>
 where

serde/src/de/utf8.rs

@@ -1,4 +1,4 @@
-use lib::*;
+use crate::lib::*;
 
 const TAG_CONT: u8 = 0b1000_0000;
 const TAG_TWO_B: u8 = 0b1100_0000;

serde/src/de/value.rs

@@ -21,12 +21,11 @@
 //! }
 //! ```
 
-use lib::*;
+use crate::lib::*;
 
 use self::private::{First, Second};
-use __private::size_hint;
+use crate::de::{self, size_hint, Deserializer, Expected, IntoDeserializer, SeqAccess, Visitor};
-use de::{self, Deserializer, Expected, IntoDeserializer, SeqAccess, Visitor};
+use crate::ser;
-use ser;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -937,8 +936,8 @@ where
     where
         V: de::Visitor<'de>,
     {
-        let v = try!(visitor.visit_seq(&mut self));
+        let v = tri!(visitor.visit_seq(&mut self));
-        try!(self.end());
+        tri!(self.end());
         Ok(v)
     }
 
@@ -1162,8 +1161,8 @@ where
     where
         V: de::Visitor<'de>,
     {
-        let value = try!(visitor.visit_map(&mut self));
+        let value = tri!(visitor.visit_map(&mut self));
-        try!(self.end());
+        tri!(self.end());
         Ok(value)
     }
 
@@ -1171,8 +1170,8 @@ where
     where
         V: de::Visitor<'de>,
     {
-        let value = try!(visitor.visit_seq(&mut self));
+        let value = tri!(visitor.visit_seq(&mut self));
-        try!(self.end());
+        tri!(self.end());
         Ok(value)
     }
 
@@ -1236,8 +1235,8 @@ where
     {
         match self.next_pair() {
             Some((key, value)) => {
-                let key = try!(kseed.deserialize(key.into_deserializer()));
+                let key = tri!(kseed.deserialize(key.into_deserializer()));
-                let value = try!(vseed.deserialize(value.into_deserializer()));
+                let value = tri!(vseed.deserialize(value.into_deserializer()));
                 Ok(Some((key, value)))
             }
             None => Ok(None),
@@ -1341,7 +1340,7 @@ where
         V: de::Visitor<'de>,
     {
         let mut pair_visitor = PairVisitor(Some(self.0), Some(self.1), PhantomData);
-        let pair = try!(visitor.visit_seq(&mut pair_visitor));
+        let pair = tri!(visitor.visit_seq(&mut pair_visitor));
         if pair_visitor.1.is_none() {
             Ok(pair)
         } else {
@@ -1501,7 +1500,7 @@ where
     where
         T: de::DeserializeSeed<'de>,
     {
-        match try!(self.map.next_key_seed(seed)) {
+        match tri!(self.map.next_key_seed(seed)) {
             Some(key) => Ok((key, private::map_as_enum(self.map))),
             None => Err(de::Error::invalid_type(de::Unexpected::Map, &"enum")),
         }
@@ -1546,9 +1545,11 @@ where
 ////////////////////////////////////////////////////////////////////////////////
 
 mod private {
-    use lib::*;
+    use crate::lib::*;
 
-    use de::{self, DeserializeSeed, Deserializer, MapAccess, Unexpected, VariantAccess, Visitor};
+    use crate::de::{
+        self, DeserializeSeed, Deserializer, MapAccess, Unexpected, VariantAccess, Visitor,
+    };
 
     pub struct UnitOnly<E> {
         marker: PhantomData<E>,

serde/src/lib.rs

@@ -93,7 +93,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.178")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.183")]
 // 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
@@ -102,55 +102,51 @@
 //    https://github.com/serde-rs/serde/issues/812
 #![cfg_attr(feature = "unstable", feature(error_in_core, never_type))]
 #![allow(unknown_lints, bare_trait_objects, deprecated)]
-#![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
 // Ignored clippy and clippy_pedantic lints
-#![cfg_attr(
+#![allow(
-    feature = "cargo-clippy",
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
-    allow(
+    clippy::unnested_or_patterns,
-        // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/7768
-        unnested_or_patterns,
+    clippy::semicolon_if_nothing_returned,
-        // clippy bug: https://github.com/rust-lang/rust-clippy/issues/7768
+    // not available in our oldest supported compiler
-        semicolon_if_nothing_returned,
+    clippy::empty_enum,
-        // not available in our oldest supported compiler
+    clippy::type_repetition_in_bounds, // https://github.com/rust-lang/rust-clippy/issues/8772
-        empty_enum,
+    // integer and float ser/de requires these sorts of casts
-        type_repetition_in_bounds, // https://github.com/rust-lang/rust-clippy/issues/8772
+    clippy::cast_possible_truncation,
-        // integer and float ser/de requires these sorts of casts
+    clippy::cast_possible_wrap,
-        cast_possible_truncation,
+    clippy::cast_sign_loss,
-        cast_possible_wrap,
+    // things are often more readable this way
-        cast_sign_loss,
+    clippy::cast_lossless,
-        // things are often more readable this way
+    clippy::module_name_repetitions,
-        cast_lossless,
+    clippy::option_if_let_else,
-        module_name_repetitions,
+    clippy::single_match_else,
-        option_if_let_else,
+    clippy::type_complexity,
-        single_match_else,
+    clippy::use_self,
-        type_complexity,
+    clippy::zero_prefixed_literal,
-        use_self,
+    // correctly used
-        zero_prefixed_literal,
+    clippy::derive_partial_eq_without_eq,
-        // correctly used
+    clippy::enum_glob_use,
-        derive_partial_eq_without_eq,
+    clippy::explicit_auto_deref,
-        enum_glob_use,
+    clippy::let_underscore_untyped,
-        explicit_auto_deref,
+    clippy::map_err_ignore,
-        let_underscore_untyped,
+    clippy::new_without_default,
-        map_err_ignore,
+    clippy::result_unit_err,
-        new_without_default,
+    clippy::wildcard_imports,
-        result_unit_err,
+    // not practical
-        wildcard_imports,
+    clippy::needless_pass_by_value,
-        // not practical
+    clippy::similar_names,
-        needless_pass_by_value,
+    clippy::too_many_lines,
-        similar_names,
+    // preference
-        too_many_lines,
+    clippy::doc_markdown,
-        // preference
+    clippy::unseparated_literal_suffix,
-        doc_markdown,
+    // false positive
-        unseparated_literal_suffix,
+    clippy::needless_doctest_main,
-        // false positive
+    // noisy
-        needless_doctest_main,
+    clippy::missing_errors_doc,
-        // noisy
+    clippy::must_use_candidate,
-        missing_errors_doc,
-        must_use_candidate,
-    )
 )]
 // Restrictions
-#![cfg_attr(feature = "cargo-clippy", deny(question_mark_used))]
+#![deny(clippy::question_mark_used)]
 // Rustc lints.
 #![deny(missing_docs, unused_imports)]
 
@@ -177,14 +173,16 @@ mod lib {
 
     pub use self::core::cell::{Cell, RefCell};
     pub use self::core::clone::{self, Clone};
+    pub use self::core::cmp::Reverse;
     pub use self::core::convert::{self, From, Into};
     pub use self::core::default::{self, Default};
     pub use self::core::fmt::{self, Debug, Display};
     pub use self::core::marker::{self, PhantomData};
     pub use self::core::num::Wrapping;
-    pub use self::core::ops::{Range, RangeFrom, RangeTo};
+    pub use self::core::ops::{Bound, Range, RangeFrom, RangeInclusive, RangeTo};
     pub use self::core::option::{self, Option};
     pub use self::core::result::{self, Result};
+    pub use self::core::time::Duration;
 
     #[cfg(all(feature = "alloc", not(feature = "std")))]
     pub use alloc::borrow::{Cow, ToOwned};
@@ -222,7 +220,7 @@ mod lib {
     pub use std::collections::{BTreeMap, BTreeSet, BinaryHeap, LinkedList, VecDeque};
 
     #[cfg(all(not(no_core_cstr), not(feature = "std")))]
-    pub use core::ffi::CStr;
+    pub use self::core::ffi::CStr;
     #[cfg(feature = "std")]
     pub use std::ffi::CStr;
 
@@ -249,18 +247,6 @@ mod lib {
     #[cfg(feature = "std")]
     pub use std::time::{SystemTime, UNIX_EPOCH};
 
-    #[cfg(all(feature = "std", not(no_collections_bound), no_ops_bound))]
-    pub use std::collections::Bound;
-
-    #[cfg(not(no_core_reverse))]
-    pub use self::core::cmp::Reverse;
-
-    #[cfg(not(no_ops_bound))]
-    pub use self::core::ops::Bound;
-
-    #[cfg(not(no_range_inclusive))]
-    pub use self::core::ops::RangeInclusive;
-
     #[cfg(all(feature = "std", no_target_has_atomic, not(no_std_atomic)))]
     pub use std::sync::atomic::{
         AtomicBool, AtomicI16, AtomicI32, AtomicI8, AtomicIsize, AtomicU16, AtomicU32, AtomicU8,
@@ -281,16 +267,13 @@ mod lib {
     pub use std::sync::atomic::{AtomicI64, AtomicU64};
     #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "ptr"))]
     pub use std::sync::atomic::{AtomicIsize, AtomicUsize};
-
-    #[cfg(any(feature = "std", not(no_core_duration)))]
-    pub use self::core::time::Duration;
 }
 
 // None of this crate's error handling needs the `From::from` error conversion
 // performed implicitly by the `?` operator or the standard library's `try!`
 // macro. This simplified macro gives a 5.5% improvement in compile time
 // compared to standard `try!`, and 9% improvement compared to `?`.
-macro_rules! try {
+macro_rules! tri {
     ($expr:expr) => {
         match $expr {
             Ok(val) => val,
@@ -311,20 +294,15 @@ pub mod de;
 pub mod ser;
 
 #[doc(inline)]
-pub use de::{Deserialize, Deserializer};
+pub use crate::de::{Deserialize, Deserializer};
 #[doc(inline)]
-pub use ser::{Serialize, Serializer};
+pub use crate::ser::{Serialize, Serializer};
 
 // Used by generated code and doc tests. Not public API.
 #[doc(hidden)]
 #[path = "private/mod.rs"]
 pub mod __private;
 
-#[allow(unused_imports)]
-use self::__private as export;
-#[allow(unused_imports)]
-use self::__private as private;
-
 #[path = "de/seed.rs"]
 mod seed;
 

serde/src/private/de.rs

@@ -1,10 +1,13 @@
-use lib::*;
+use crate::lib::*;
 
-use de::value::{BorrowedBytesDeserializer, BytesDeserializer};
+use crate::de::value::{BorrowedBytesDeserializer, BytesDeserializer};
-use de::{Deserialize, Deserializer, Error, IntoDeserializer, Visitor};
+use crate::de::{
+    Deserialize, DeserializeSeed, Deserializer, EnumAccess, Error, IntoDeserializer, VariantAccess,
+    Visitor,
+};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-use de::{DeserializeSeed, MapAccess, Unexpected};
+use crate::de::{MapAccess, Unexpected};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 pub use self::content::{
@@ -13,7 +16,7 @@ pub use self::content::{
     TagOrContentField, TagOrContentFieldVisitor, TaggedContentVisitor, UntaggedUnitVisitor,
 };
 
-pub use seed::InPlaceSeed;
+pub use crate::seed::InPlaceSeed;
 
 /// If the missing field is of type `Option<T>` then treat is as `None`,
 /// otherwise it is an error.
@@ -203,13 +206,13 @@ mod content {
     // This issue is tracking making some of this stuff public:
     // https://github.com/serde-rs/serde/issues/741
 
-    use lib::*;
+    use crate::lib::*;
 
-    use __private::size_hint;
+    use crate::actually_private;
-    use actually_private;
+    use crate::de::value::{MapDeserializer, SeqDeserializer};
-    use de::{
+    use crate::de::{
-        self, Deserialize, DeserializeSeed, Deserializer, EnumAccess, Expected, IgnoredAny,
+        self, size_hint, Deserialize, DeserializeSeed, Deserializer, EnumAccess, Expected,
-        MapAccess, SeqAccess, Unexpected, Visitor,
+        IgnoredAny, MapAccess, SeqAccess, Unexpected, Visitor,
     };
 
     /// Used from generated code to buffer the contents of the Deserializer when
@@ -299,6 +302,17 @@ mod content {
         }
     }
 
+    impl<'de, E> de::IntoDeserializer<'de, E> for Content<'de>
+    where
+        E: de::Error,
+    {
+        type Deserializer = ContentDeserializer<'de, E>;
+
+        fn into_deserializer(self) -> Self::Deserializer {
+            ContentDeserializer::new(self)
+        }
+    }
+
     struct ContentVisitor<'de> {
         value: PhantomData<Content<'de>>,
     }
@@ -476,7 +490,7 @@ mod content {
         {
             let mut vec =
                 Vec::<Content>::with_capacity(size_hint::cautious::<Content>(visitor.size_hint()));
-            while let Some(e) = try!(visitor.next_element()) {
+            while let Some(e) = tri!(visitor.next_element()) {
                 vec.push(e);
             }
             Ok(Content::Seq(vec))
@@ -490,7 +504,7 @@ mod content {
                 Vec::<(Content, Content)>::with_capacity(
                     size_hint::cautious::<(Content, Content)>(visitor.size_hint()),
                 );
-            while let Some(kv) = try!(visitor.next_entry()) {
+            while let Some(kv) = tri!(visitor.next_entry()) {
                 vec.push(kv);
             }
             Ok(Content::Map(vec))
@@ -833,14 +847,14 @@ mod content {
         where
             S: SeqAccess<'de>,
         {
-            let tag = match try!(seq.next_element()) {
+            let tag = match tri!(seq.next_element()) {
                 Some(tag) => tag,
                 None => {
                     return Err(de::Error::missing_field(self.tag_name));
                 }
             };
             let rest = de::value::SeqAccessDeserializer::new(seq);
-            Ok((tag, try!(Content::deserialize(rest))))
+            Ok((tag, tri!(Content::deserialize(rest))))
         }
 
         fn visit_map<M>(self, mut map: M) -> Result<Self::Value, M::Error>
@@ -852,16 +866,16 @@ mod content {
                 Content,
                 Content,
             )>(map.size_hint()));
-            while let Some(k) = try!(map.next_key_seed(TagOrContentVisitor::new(self.tag_name))) {
+            while let Some(k) = tri!(map.next_key_seed(TagOrContentVisitor::new(self.tag_name))) {
                 match k {
                     TagOrContent::Tag => {
                         if tag.is_some() {
                             return Err(de::Error::duplicate_field(self.tag_name));
                         }
-                        tag = Some(try!(map.next_value()));
+                        tag = Some(tri!(map.next_value()));
                     }
                     TagOrContent::Content(k) => {
-                        let v = try!(map.next_value());
+                        let v = tri!(map.next_value());
                         vec.push((k, v));
                     }
                 }
@@ -1074,9 +1088,9 @@ mod content {
         E: de::Error,
     {
         let seq = content.into_iter().map(ContentDeserializer::new);
-        let mut seq_visitor = de::value::SeqDeserializer::new(seq);
+        let mut seq_visitor = SeqDeserializer::new(seq);
-        let value = try!(visitor.visit_seq(&mut seq_visitor));
+        let value = tri!(visitor.visit_seq(&mut seq_visitor));
-        try!(seq_visitor.end());
+        tri!(seq_visitor.end());
         Ok(value)
     }
 
@@ -1091,9 +1105,9 @@ mod content {
         let map = content
             .into_iter()
             .map(|(k, v)| (ContentDeserializer::new(k), ContentDeserializer::new(v)));
-        let mut map_visitor = de::value::MapDeserializer::new(map);
+        let mut map_visitor = MapDeserializer::new(map);
-        let value = try!(visitor.visit_map(&mut map_visitor));
+        let value = tri!(visitor.visit_map(&mut map_visitor));
-        try!(map_visitor.end());
+        tri!(map_visitor.end());
         Ok(value)
     }
 
@@ -1569,7 +1583,7 @@ mod content {
         {
             match self.value {
                 Some(Content::Seq(v)) => {
-                    de::Deserializer::deserialize_any(SeqDeserializer::new(v), visitor)
+                    de::Deserializer::deserialize_any(SeqDeserializer::new(v.into_iter()), visitor)
                 }
                 Some(other) => Err(de::Error::invalid_type(
                     other.unexpected(),
@@ -1592,10 +1606,10 @@ mod content {
         {
             match self.value {
                 Some(Content::Map(v)) => {
-                    de::Deserializer::deserialize_any(MapDeserializer::new(v), visitor)
+                    de::Deserializer::deserialize_any(MapDeserializer::new(v.into_iter()), visitor)
                 }
                 Some(Content::Seq(v)) => {
-                    de::Deserializer::deserialize_any(SeqDeserializer::new(v), visitor)
+                    de::Deserializer::deserialize_any(SeqDeserializer::new(v.into_iter()), visitor)
                 }
                 Some(other) => Err(de::Error::invalid_type(
                     other.unexpected(),
@@ -1609,156 +1623,6 @@ mod content {
         }
     }
 
-    struct SeqDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        iter: <Vec<Content<'de>> as IntoIterator>::IntoIter,
-        err: PhantomData<E>,
-    }
-
-    impl<'de, E> SeqDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        fn new(vec: Vec<Content<'de>>) -> Self {
-            SeqDeserializer {
-                iter: vec.into_iter(),
-                err: PhantomData,
-            }
-        }
-    }
-
-    impl<'de, E> de::Deserializer<'de> for SeqDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        type Error = E;
-
-        #[inline]
-        fn deserialize_any<V>(mut self, visitor: V) -> Result<V::Value, Self::Error>
-        where
-            V: de::Visitor<'de>,
-        {
-            let len = self.iter.len();
-            if len == 0 {
-                visitor.visit_unit()
-            } else {
-                let ret = try!(visitor.visit_seq(&mut self));
-                let remaining = self.iter.len();
-                if remaining == 0 {
-                    Ok(ret)
-                } else {
-                    Err(de::Error::invalid_length(len, &"fewer elements in array"))
-                }
-            }
-        }
-
-        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<'de, E> de::SeqAccess<'de> for SeqDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        type Error = E;
-
-        fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
-        where
-            T: de::DeserializeSeed<'de>,
-        {
-            match self.iter.next() {
-                Some(value) => seed.deserialize(ContentDeserializer::new(value)).map(Some),
-                None => Ok(None),
-            }
-        }
-
-        fn size_hint(&self) -> Option<usize> {
-            size_hint::from_bounds(&self.iter)
-        }
-    }
-
-    struct MapDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        iter: <Vec<(Content<'de>, Content<'de>)> as IntoIterator>::IntoIter,
-        value: Option<Content<'de>>,
-        err: PhantomData<E>,
-    }
-
-    impl<'de, E> MapDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        fn new(map: Vec<(Content<'de>, Content<'de>)>) -> Self {
-            MapDeserializer {
-                iter: map.into_iter(),
-                value: None,
-                err: PhantomData,
-            }
-        }
-    }
-
-    impl<'de, E> de::MapAccess<'de> for MapDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        type Error = E;
-
-        fn next_key_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
-        where
-            T: de::DeserializeSeed<'de>,
-        {
-            match self.iter.next() {
-                Some((key, value)) => {
-                    self.value = Some(value);
-                    seed.deserialize(ContentDeserializer::new(key)).map(Some)
-                }
-                None => Ok(None),
-            }
-        }
-
-        fn next_value_seed<T>(&mut self, seed: T) -> Result<T::Value, Self::Error>
-        where
-            T: de::DeserializeSeed<'de>,
-        {
-            match self.value.take() {
-                Some(value) => seed.deserialize(ContentDeserializer::new(value)),
-                None => Err(de::Error::custom("value is missing")),
-            }
-        }
-
-        fn size_hint(&self) -> Option<usize> {
-            size_hint::from_bounds(&self.iter)
-        }
-    }
-
-    impl<'de, E> de::Deserializer<'de> for MapDeserializer<'de, E>
-    where
-        E: de::Error,
-    {
-        type Error = E;
-
-        #[inline]
-        fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
-        where
-            V: de::Visitor<'de>,
-        {
-            visitor.visit_map(self)
-        }
-
-        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
-        }
-    }
-
     /// Not public API.
     pub struct ContentRefDeserializer<'a, 'de: 'a, E> {
         content: &'a Content<'de>,
@@ -1820,9 +1684,9 @@ mod content {
         E: de::Error,
     {
         let seq = content.iter().map(ContentRefDeserializer::new);
-        let mut seq_visitor = de::value::SeqDeserializer::new(seq);
+        let mut seq_visitor = SeqDeserializer::new(seq);
-        let value = try!(visitor.visit_seq(&mut seq_visitor));
+        let value = tri!(visitor.visit_seq(&mut seq_visitor));
-        try!(seq_visitor.end());
+        tri!(seq_visitor.end());
         Ok(value)
     }
 
@@ -1840,9 +1704,9 @@ mod content {
                 ContentRefDeserializer::new(v),
             )
         });
-        let mut map_visitor = de::value::MapDeserializer::new(map);
+        let mut map_visitor = MapDeserializer::new(map);
-        let value = try!(visitor.visit_map(&mut map_visitor));
+        let value = tri!(visitor.visit_map(&mut map_visitor));
-        try!(map_visitor.end());
+        tri!(map_visitor.end());
         Ok(value)
     }
 
@@ -2362,7 +2226,7 @@ mod content {
             if len == 0 {
                 visitor.visit_unit()
             } else {
-                let ret = try!(visitor.visit_seq(&mut self));
+                let ret = tri!(visitor.visit_seq(&mut self));
                 let remaining = self.iter.len();
                 if remaining == 0 {
                     Ok(ret)
@@ -2541,7 +2405,7 @@ mod content {
         where
             M: MapAccess<'de>,
         {
-            while try!(access.next_entry::<IgnoredAny, IgnoredAny>()).is_some() {}
+            while tri!(access.next_entry::<IgnoredAny, IgnoredAny>()).is_some() {}
             Ok(())
         }
     }
@@ -2974,3 +2838,55 @@ fn flat_map_take_entry<'de>(
         None
     }
 }
+
+pub struct AdjacentlyTaggedEnumVariantSeed<F> {
+    pub enum_name: &'static str,
+    pub variants: &'static [&'static str],
+    pub fields_enum: PhantomData<F>,
+}
+
+pub struct AdjacentlyTaggedEnumVariantVisitor<F> {
+    enum_name: &'static str,
+    fields_enum: PhantomData<F>,
+}
+
+impl<'de, F> Visitor<'de> for AdjacentlyTaggedEnumVariantVisitor<F>
+where
+    F: Deserialize<'de>,
+{
+    type Value = F;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        write!(formatter, "variant of enum {}", self.enum_name)
+    }
+
+    fn visit_enum<A>(self, data: A) -> Result<Self::Value, A::Error>
+    where
+        A: EnumAccess<'de>,
+    {
+        let (variant, variant_access) = tri!(data.variant());
+        tri!(variant_access.unit_variant());
+        Ok(variant)
+    }
+}
+
+impl<'de, F> DeserializeSeed<'de> for AdjacentlyTaggedEnumVariantSeed<F>
+where
+    F: Deserialize<'de>,
+{
+    type Value = F;
+
+    fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_enum(
+            self.enum_name,
+            self.variants,
+            AdjacentlyTaggedEnumVariantVisitor {
+                enum_name: self.enum_name,
+                fields_enum: PhantomData,
+            },
+        )
+    }
+}

serde/src/private/doc.rs

@@ -1,8 +1,8 @@
 // Used only by Serde doc tests. Not public API.
 
-use lib::*;
+use crate::lib::*;
 
-use ser;
+use crate::ser;
 
 #[doc(hidden)]
 #[derive(Debug)]

serde/src/private/mod.rs

@@ -3,30 +3,28 @@ pub mod de;
 #[cfg(not(no_serde_derive))]
 pub mod ser;
 
-pub mod size_hint;
-
 // FIXME: #[cfg(doctest)] once https://github.com/rust-lang/rust/issues/67295 is fixed.
 pub mod doc;
 
-pub use lib::clone::Clone;
+pub use crate::lib::clone::Clone;
-pub use lib::convert::{From, Into};
+pub use crate::lib::convert::{From, Into};
-pub use lib::default::Default;
+pub use crate::lib::default::Default;
-pub use lib::fmt::{self, Formatter};
+pub use crate::lib::fmt::{self, Formatter};
-pub use lib::marker::PhantomData;
+pub use crate::lib::marker::PhantomData;
-pub use lib::option::Option::{self, None, Some};
+pub use crate::lib::option::Option::{self, None, Some};
-pub use lib::ptr;
+pub use crate::lib::ptr;
-pub use lib::result::Result::{self, Err, Ok};
+pub use crate::lib::result::Result::{self, Err, Ok};
 
 pub use self::string::from_utf8_lossy;
 
 #[cfg(any(feature = "alloc", feature = "std"))]
-pub use lib::{ToString, Vec};
+pub use crate::lib::{ToString, Vec};
 
 #[cfg(not(no_core_try_from))]
-pub use lib::convert::TryFrom;
+pub use crate::lib::convert::TryFrom;
 
 mod string {
-    use lib::*;
+    use crate::lib::*;
 
     #[cfg(any(feature = "std", feature = "alloc"))]
     pub fn from_utf8_lossy(bytes: &[u8]) -> Cow<str> {

serde/src/private/ser.rs

@@ -1,6 +1,6 @@
-use lib::*;
+use crate::lib::*;
 
-use ser::{self, Impossible, Serialize, SerializeMap, SerializeStruct, Serializer};
+use crate::ser::{self, Impossible, Serialize, SerializeMap, SerializeStruct, Serializer};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 use self::content::{
@@ -182,14 +182,14 @@ where
     }
 
     fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {
-        let mut map = try!(self.delegate.serialize_map(Some(1)));
+        let mut map = tri!(self.delegate.serialize_map(Some(1)));
-        try!(map.serialize_entry(self.tag, self.variant_name));
+        tri!(map.serialize_entry(self.tag, self.variant_name));
         map.end()
     }
 
     fn serialize_unit_struct(self, _: &'static str) -> Result<Self::Ok, Self::Error> {
-        let mut map = try!(self.delegate.serialize_map(Some(1)));
+        let mut map = tri!(self.delegate.serialize_map(Some(1)));
-        try!(map.serialize_entry(self.tag, self.variant_name));
+        tri!(map.serialize_entry(self.tag, self.variant_name));
         map.end()
     }
 
@@ -199,9 +199,9 @@ where
         _: u32,
         inner_variant: &'static str,
     ) -> Result<Self::Ok, Self::Error> {
-        let mut map = try!(self.delegate.serialize_map(Some(2)));
+        let mut map = tri!(self.delegate.serialize_map(Some(2)));
-        try!(map.serialize_entry(self.tag, self.variant_name));
+        tri!(map.serialize_entry(self.tag, self.variant_name));
-        try!(map.serialize_entry(inner_variant, &()));
+        tri!(map.serialize_entry(inner_variant, &()));
         map.end()
     }
 
@@ -226,9 +226,9 @@ where
     where
         T: Serialize,
     {
-        let mut map = try!(self.delegate.serialize_map(Some(2)));
+        let mut map = tri!(self.delegate.serialize_map(Some(2)));
-        try!(map.serialize_entry(self.tag, self.variant_name));
+        tri!(map.serialize_entry(self.tag, self.variant_name));
-        try!(map.serialize_entry(inner_variant, inner_value));
+        tri!(map.serialize_entry(inner_variant, inner_value));
         map.end()
     }
 
@@ -269,9 +269,9 @@ where
         inner_variant: &'static str,
         len: usize,
     ) -> Result<Self::SerializeTupleVariant, Self::Error> {
-        let mut map = try!(self.delegate.serialize_map(Some(2)));
+        let mut map = tri!(self.delegate.serialize_map(Some(2)));
-        try!(map.serialize_entry(self.tag, self.variant_name));
+        tri!(map.serialize_entry(self.tag, self.variant_name));
-        try!(map.serialize_key(inner_variant));
+        tri!(map.serialize_key(inner_variant));
         Ok(SerializeTupleVariantAsMapValue::new(
             map,
             inner_variant,
@@ -280,8 +280,8 @@ where
     }
 
     fn serialize_map(self, len: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
-        let mut map = try!(self.delegate.serialize_map(len.map(|len| len + 1)));
+        let mut map = tri!(self.delegate.serialize_map(len.map(|len| len + 1)));
-        try!(map.serialize_entry(self.tag, self.variant_name));
+        tri!(map.serialize_entry(self.tag, self.variant_name));
         Ok(map)
     }
 
@@ -290,8 +290,8 @@ where
         name: &'static str,
         len: usize,
     ) -> Result<Self::SerializeStruct, Self::Error> {
-        let mut state = try!(self.delegate.serialize_struct(name, len + 1));
+        let mut state = tri!(self.delegate.serialize_struct(name, len + 1));
-        try!(state.serialize_field(self.tag, self.variant_name));
+        tri!(state.serialize_field(self.tag, self.variant_name));
         Ok(state)
     }
 
@@ -316,9 +316,9 @@ where
         inner_variant: &'static str,
         len: usize,
     ) -> Result<Self::SerializeStructVariant, Self::Error> {
-        let mut map = try!(self.delegate.serialize_map(Some(2)));
+        let mut map = tri!(self.delegate.serialize_map(Some(2)));
-        try!(map.serialize_entry(self.tag, self.variant_name));
+        tri!(map.serialize_entry(self.tag, self.variant_name));
-        try!(map.serialize_key(inner_variant));
+        tri!(map.serialize_key(inner_variant));
         Ok(SerializeStructVariantAsMapValue::new(
             map,
             inner_variant,
@@ -337,9 +337,9 @@ where
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 mod content {
-    use lib::*;
+    use crate::lib::*;
 
-    use ser::{self, Serialize, Serializer};
+    use crate::ser::{self, Serialize, Serializer};
 
     pub struct SerializeTupleVariantAsMapValue<M> {
         map: M,
@@ -368,13 +368,13 @@ mod content {
         where
             T: Serialize,
         {
-            let value = try!(value.serialize(ContentSerializer::<M::Error>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<M::Error>::new()));
             self.fields.push(value);
             Ok(())
         }
 
         fn end(mut self) -> Result<M::Ok, M::Error> {
-            try!(self
+            tri!(self
                 .map
                 .serialize_value(&Content::TupleStruct(self.name, self.fields)));
             self.map.end()
@@ -412,13 +412,13 @@ mod content {
         where
             T: Serialize,
         {
-            let value = try!(value.serialize(ContentSerializer::<M::Error>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<M::Error>::new()));
             self.fields.push((key, value));
             Ok(())
         }
 
         fn end(mut self) -> Result<M::Ok, M::Error> {
-            try!(self
+            tri!(self
                 .map
                 .serialize_value(&Content::Struct(self.name, self.fields)));
             self.map.end()
@@ -499,50 +499,50 @@ mod content {
                 }
                 Content::Seq(ref elements) => elements.serialize(serializer),
                 Content::Tuple(ref elements) => {
-                    use ser::SerializeTuple;
+                    use crate::ser::SerializeTuple;
-                    let mut tuple = try!(serializer.serialize_tuple(elements.len()));
+                    let mut tuple = tri!(serializer.serialize_tuple(elements.len()));
                     for e in elements {
-                        try!(tuple.serialize_element(e));
+                        tri!(tuple.serialize_element(e));
                     }
                     tuple.end()
                 }
                 Content::TupleStruct(n, ref fields) => {
-                    use ser::SerializeTupleStruct;
+                    use crate::ser::SerializeTupleStruct;
-                    let mut ts = try!(serializer.serialize_tuple_struct(n, fields.len()));
+                    let mut ts = tri!(serializer.serialize_tuple_struct(n, fields.len()));
                     for f in fields {
-                        try!(ts.serialize_field(f));
+                        tri!(ts.serialize_field(f));
                     }
                     ts.end()
                 }
                 Content::TupleVariant(n, i, v, ref fields) => {
-                    use ser::SerializeTupleVariant;
+                    use crate::ser::SerializeTupleVariant;
-                    let mut tv = try!(serializer.serialize_tuple_variant(n, i, v, fields.len()));
+                    let mut tv = tri!(serializer.serialize_tuple_variant(n, i, v, fields.len()));
                     for f in fields {
-                        try!(tv.serialize_field(f));
+                        tri!(tv.serialize_field(f));
                     }
                     tv.end()
                 }
                 Content::Map(ref entries) => {
-                    use ser::SerializeMap;
+                    use crate::ser::SerializeMap;
-                    let mut map = try!(serializer.serialize_map(Some(entries.len())));
+                    let mut map = tri!(serializer.serialize_map(Some(entries.len())));
                     for (k, v) in entries {
-                        try!(map.serialize_entry(k, v));
+                        tri!(map.serialize_entry(k, v));
                     }
                     map.end()
                 }
                 Content::Struct(n, ref fields) => {
-                    use ser::SerializeStruct;
+                    use crate::ser::SerializeStruct;
-                    let mut s = try!(serializer.serialize_struct(n, fields.len()));
+                    let mut s = tri!(serializer.serialize_struct(n, fields.len()));
                     for &(k, ref v) in fields {
-                        try!(s.serialize_field(k, v));
+                        tri!(s.serialize_field(k, v));
                     }
                     s.end()
                 }
                 Content::StructVariant(n, i, v, ref fields) => {
-                    use ser::SerializeStructVariant;
+                    use crate::ser::SerializeStructVariant;
-                    let mut sv = try!(serializer.serialize_struct_variant(n, i, v, fields.len()));
+                    let mut sv = tri!(serializer.serialize_struct_variant(n, i, v, fields.len()));
                     for &(k, ref v) in fields {
-                        try!(sv.serialize_field(k, v));
+                        tri!(sv.serialize_field(k, v));
                     }
                     sv.end()
                 }
@@ -639,7 +639,7 @@ mod content {
         where
             T: Serialize,
         {
-            Ok(Content::Some(Box::new(try!(value.serialize(self)))))
+            Ok(Content::Some(Box::new(tri!(value.serialize(self)))))
         }
 
         fn serialize_unit(self) -> Result<Content, E> {
@@ -669,7 +669,7 @@ mod content {
         {
             Ok(Content::NewtypeStruct(
                 name,
-                Box::new(try!(value.serialize(self))),
+                Box::new(tri!(value.serialize(self))),
             ))
         }
 
@@ -687,7 +687,7 @@ mod content {
                 name,
                 variant_index,
                 variant,
-                Box::new(try!(value.serialize(self))),
+                Box::new(tri!(value.serialize(self))),
             ))
         }
 
@@ -786,7 +786,7 @@ mod content {
         where
             T: Serialize,
         {
-            let value = try!(value.serialize(ContentSerializer::<E>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<E>::new()));
             self.elements.push(value);
             Ok(())
         }
@@ -812,7 +812,7 @@ mod content {
         where
             T: Serialize,
         {
-            let value = try!(value.serialize(ContentSerializer::<E>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<E>::new()));
             self.elements.push(value);
             Ok(())
         }
@@ -839,7 +839,7 @@ mod content {
         where
             T: Serialize,
         {
-            let value = try!(value.serialize(ContentSerializer::<E>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<E>::new()));
             self.fields.push(value);
             Ok(())
         }
@@ -868,7 +868,7 @@ mod content {
         where
             T: Serialize,
         {
-            let value = try!(value.serialize(ContentSerializer::<E>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<E>::new()));
             self.fields.push(value);
             Ok(())
         }
@@ -900,7 +900,7 @@ mod content {
         where
             T: Serialize,
         {
-            let key = try!(key.serialize(ContentSerializer::<E>::new()));
+            let key = tri!(key.serialize(ContentSerializer::<E>::new()));
             self.key = Some(key);
             Ok(())
         }
@@ -913,7 +913,7 @@ mod content {
                 .key
                 .take()
                 .expect("serialize_value called before serialize_key");
-            let value = try!(value.serialize(ContentSerializer::<E>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<E>::new()));
             self.entries.push((key, value));
             Ok(())
         }
@@ -927,8 +927,8 @@ mod content {
             K: Serialize,
             V: Serialize,
         {
-            let key = try!(key.serialize(ContentSerializer::<E>::new()));
+            let key = tri!(key.serialize(ContentSerializer::<E>::new()));
-            let value = try!(value.serialize(ContentSerializer::<E>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<E>::new()));
             self.entries.push((key, value));
             Ok(())
         }
@@ -951,7 +951,7 @@ mod content {
         where
             T: Serialize,
         {
-            let value = try!(value.serialize(ContentSerializer::<E>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<E>::new()));
             self.fields.push((key, value));
             Ok(())
         }
@@ -980,7 +980,7 @@ mod content {
         where
             T: Serialize,
         {
-            let value = try!(value.serialize(ContentSerializer::<E>::new()));
+            let value = tri!(value.serialize(ContentSerializer::<E>::new()));
             self.fields.push((key, value));
             Ok(())
         }
@@ -1025,7 +1025,7 @@ where
     type SerializeTupleStruct = Impossible<Self::Ok, M::Error>;
     type SerializeMap = FlatMapSerializeMap<'a, M>;
     type SerializeStruct = FlatMapSerializeStruct<'a, M>;
-    type SerializeTupleVariant = Impossible<Self::Ok, M::Error>;
+    type SerializeTupleVariant = FlatMapSerializeTupleVariantAsMapValue<'a, M>;
     type SerializeStructVariant = FlatMapSerializeStructVariantAsMapValue<'a, M>;
 
     fn serialize_bool(self, _: bool) -> Result<Self::Ok, Self::Error> {
@@ -1133,7 +1133,7 @@ where
     where
         T: Serialize,
     {
-        try!(self.0.serialize_key(variant));
+        tri!(self.0.serialize_key(variant));
         self.0.serialize_value(value)
     }
 
@@ -1157,10 +1157,11 @@ where
         self,
         _: &'static str,
         _: u32,
-        _: &'static str,
+        variant: &'static str,
         _: usize,
     ) -> Result<Self::SerializeTupleVariant, Self::Error> {
-        Err(Self::bad_type(Unsupported::Enum))
+        tri!(self.0.serialize_key(variant));
+        Ok(FlatMapSerializeTupleVariantAsMapValue::new(self.0))
     }
 
     fn serialize_map(self, _: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
@@ -1182,7 +1183,7 @@ where
         inner_variant: &'static str,
         _: usize,
     ) -> Result<Self::SerializeStructVariant, Self::Error> {
-        try!(self.0.serialize_key(inner_variant));
+        tri!(self.0.serialize_key(inner_variant));
         Ok(FlatMapSerializeStructVariantAsMapValue::new(
             self.0,
             inner_variant,
@@ -1259,6 +1260,52 @@ where
     }
 }
 
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+pub struct FlatMapSerializeTupleVariantAsMapValue<'a, M: 'a> {
+    map: &'a mut M,
+    fields: Vec<Content>,
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, M> FlatMapSerializeTupleVariantAsMapValue<'a, M>
+where
+    M: SerializeMap + 'a,
+{
+    fn new(map: &'a mut M) -> Self {
+        FlatMapSerializeTupleVariantAsMapValue {
+            map,
+            fields: Vec::new(),
+        }
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, M> ser::SerializeTupleVariant for FlatMapSerializeTupleVariantAsMapValue<'a, M>
+where
+    M: SerializeMap + 'a,
+{
+    type Ok = ();
+    type Error = M::Error;
+
+    fn serialize_field<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
+    where
+        T: Serialize,
+    {
+        let value = tri!(value.serialize(ContentSerializer::<M::Error>::new()));
+        self.fields.push(value);
+        Ok(())
+    }
+
+    fn end(self) -> Result<(), Self::Error> {
+        tri!(self.map.serialize_value(&Content::Seq(self.fields)));
+        Ok(())
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
 #[cfg(any(feature = "std", feature = "alloc"))]
 pub struct FlatMapSerializeStructVariantAsMapValue<'a, M: 'a> {
     map: &'a mut M,
@@ -1296,15 +1343,30 @@ where
     where
         T: Serialize,
     {
-        let value = try!(value.serialize(ContentSerializer::<M::Error>::new()));
+        let value = tri!(value.serialize(ContentSerializer::<M::Error>::new()));
         self.fields.push((key, value));
         Ok(())
     }
 
     fn end(self) -> Result<(), Self::Error> {
-        try!(self
+        tri!(self
             .map
             .serialize_value(&Content::Struct(self.name, self.fields)));
         Ok(())
     }
 }
+
+pub struct AdjacentlyTaggedEnumVariant {
+    pub enum_name: &'static str,
+    pub variant_index: u32,
+    pub variant_name: &'static str,
+}
+
+impl Serialize for AdjacentlyTaggedEnumVariant {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_unit_variant(self.enum_name, self.variant_index, self.variant_name)
+    }
+}

serde/src/ser/fmt.rs

@@ -1,5 +1,5 @@
-use lib::*;
+use crate::lib::*;
-use ser::{Error, Impossible, Serialize, Serializer};
+use crate::ser::{Error, Impossible, Serialize, Serializer};
 
 impl Error for fmt::Error {
     fn custom<T: Display>(_msg: T) -> Self {

serde/src/ser/impls.rs

@@ -1,6 +1,6 @@
-use lib::*;
+use crate::lib::*;
 
-use ser::{Error, Serialize, SerializeTuple, Serializer};
+use crate::ser::{Error, Serialize, SerializeTuple, Serializer};
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -133,7 +133,7 @@ impl<T> Serialize for [T; 0] {
     where
         S: Serializer,
     {
-        try!(serializer.serialize_tuple(0)).end()
+        tri!(serializer.serialize_tuple(0)).end()
     }
 }
 
@@ -149,9 +149,9 @@ macro_rules! array_impls {
                 where
                     S: Serializer,
                 {
-                    let mut seq = try!(serializer.serialize_tuple($len));
+                    let mut seq = tri!(serializer.serialize_tuple($len));
                     for e in self {
-                        try!(seq.serialize_element(e));
+                        tri!(seq.serialize_element(e));
                     }
                     seq.end()
                 }
@@ -248,9 +248,9 @@ where
         S: Serializer,
     {
         use super::SerializeStruct;
-        let mut state = try!(serializer.serialize_struct("Range", 2));
+        let mut state = tri!(serializer.serialize_struct("Range", 2));
-        try!(state.serialize_field("start", &self.start));
+        tri!(state.serialize_field("start", &self.start));
-        try!(state.serialize_field("end", &self.end));
+        tri!(state.serialize_field("end", &self.end));
         state.end()
     }
 }
@@ -266,15 +266,14 @@ where
         S: Serializer,
     {
         use super::SerializeStruct;
-        let mut state = try!(serializer.serialize_struct("RangeFrom", 1));
+        let mut state = tri!(serializer.serialize_struct("RangeFrom", 1));
-        try!(state.serialize_field("start", &self.start));
+        tri!(state.serialize_field("start", &self.start));
         state.end()
     }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(not(no_range_inclusive))]
 impl<Idx> Serialize for RangeInclusive<Idx>
 where
     Idx: Serialize,
@@ -284,9 +283,9 @@ where
         S: Serializer,
     {
         use super::SerializeStruct;
-        let mut state = try!(serializer.serialize_struct("RangeInclusive", 2));
+        let mut state = tri!(serializer.serialize_struct("RangeInclusive", 2));
-        try!(state.serialize_field("start", &self.start()));
+        tri!(state.serialize_field("start", &self.start()));
-        try!(state.serialize_field("end", &self.end()));
+        tri!(state.serialize_field("end", &self.end()));
         state.end()
     }
 }
@@ -302,15 +301,14 @@ where
         S: Serializer,
     {
         use super::SerializeStruct;
-        let mut state = try!(serializer.serialize_struct("RangeTo", 1));
+        let mut state = tri!(serializer.serialize_struct("RangeTo", 1));
-        try!(state.serialize_field("end", &self.end));
+        tri!(state.serialize_field("end", &self.end));
         state.end()
     }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(not(no_ops_bound), all(feature = "std", not(no_collections_bound))))]
 impl<T> Serialize for Bound<T>
 where
     T: Serialize,
@@ -367,9 +365,9 @@ macro_rules! tuple_impls {
                 where
                     S: Serializer,
                 {
-                    let mut tuple = try!(serializer.serialize_tuple($len));
+                    let mut tuple = tri!(serializer.serialize_tuple($len));
                     $(
-                        try!(tuple.serialize_element(&self.$n));
+                        tri!(tuple.serialize_element(&self.$n));
                     )+
                     tuple.end()
                 }
@@ -538,7 +536,6 @@ where
 macro_rules! nonzero_integers {
     ($($T:ident,)+) => {
         $(
-            #[cfg(not(no_num_nonzero))]
             impl Serialize for num::$T {
                 fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
                 where
@@ -662,16 +659,15 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(feature = "std", not(no_core_duration)))]
 impl Serialize for Duration {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
         S: Serializer,
     {
         use super::SerializeStruct;
-        let mut state = try!(serializer.serialize_struct("Duration", 2));
+        let mut state = tri!(serializer.serialize_struct("Duration", 2));
-        try!(state.serialize_field("secs", &self.as_secs()));
+        tri!(state.serialize_field("secs", &self.as_secs()));
-        try!(state.serialize_field("nanos", &self.subsec_nanos()));
+        tri!(state.serialize_field("nanos", &self.subsec_nanos()));
         state.end()
     }
 }
@@ -689,9 +685,9 @@ impl Serialize for SystemTime {
             Ok(duration_since_epoch) => duration_since_epoch,
             Err(_) => return Err(S::Error::custom("SystemTime must be later than UNIX_EPOCH")),
         };
-        let mut state = try!(serializer.serialize_struct("SystemTime", 2));
+        let mut state = tri!(serializer.serialize_struct("SystemTime", 2));
-        try!(state.serialize_field("secs_since_epoch", &duration_since_epoch.as_secs()));
+        tri!(state.serialize_field("secs_since_epoch", &duration_since_epoch.as_secs()));
-        try!(state.serialize_field("nanos_since_epoch", &duration_since_epoch.subsec_nanos()));
+        tri!(state.serialize_field("nanos_since_epoch", &duration_since_epoch.subsec_nanos()));
         state.end()
     }
 }
@@ -963,7 +959,6 @@ where
     }
 }
 
-#[cfg(not(no_core_reverse))]
 impl<T> Serialize for Reverse<T>
 where
     T: Serialize,

serde/src/ser/impossible.rs

@@ -1,8 +1,8 @@
 //! This module contains `Impossible` serializer and its implementations.
 
-use lib::*;
+use crate::lib::*;
 
-use ser::{
+use crate::ser::{
     self, Serialize, SerializeMap, SerializeSeq, SerializeStruct, SerializeStructVariant,
     SerializeTuple, SerializeTupleStruct, SerializeTupleVariant,
 };

serde/src/ser/mod.rs

@@ -107,7 +107,7 @@
 //! [derive section of the manual]: https://serde.rs/derive.html
 //! [data formats]: https://serde.rs/#data-formats
 
-use lib::*;
+use crate::lib::*;
 
 mod fmt;
 mod impls;
@@ -115,15 +115,15 @@ mod impossible;
 
 pub use self::impossible::Impossible;
 
+#[cfg(not(any(feature = "std", feature = "unstable")))]
+#[doc(no_inline)]
+pub use crate::std_error::Error as StdError;
 #[cfg(all(feature = "unstable", not(feature = "std")))]
 #[doc(no_inline)]
 pub use core::error::Error as StdError;
 #[cfg(feature = "std")]
 #[doc(no_inline)]
 pub use std::error::Error as StdError;
-#[cfg(not(any(feature = "std", feature = "unstable")))]
-#[doc(no_inline)]
-pub use std_error::Error as StdError;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -1279,22 +1279,9 @@ pub trait Serializer: Sized {
         I: IntoIterator,
         <I as IntoIterator>::Item: Serialize,
     {
-        let iter = iter.into_iter();
+        let mut iter = iter.into_iter();
-        let mut serializer = try!(self.serialize_seq(iterator_len_hint(&iter)));
+        let mut serializer = tri!(self.serialize_seq(iterator_len_hint(&iter)));
-
+        tri!(iter.try_for_each(|item| serializer.serialize_element(&item)));
-        #[cfg(not(no_iterator_try_fold))]
-        {
-            let mut iter = iter;
-            try!(iter.try_for_each(|item| serializer.serialize_element(&item)));
-        }
-
-        #[cfg(no_iterator_try_fold)]
-        {
-            for item in iter {
-                try!(serializer.serialize_element(&item));
-            }
-        }
-
         serializer.end()
     }
 
@@ -1330,22 +1317,9 @@ pub trait Serializer: Sized {
         V: Serialize,
         I: IntoIterator<Item = (K, V)>,
     {
-        let iter = iter.into_iter();
+        let mut iter = iter.into_iter();
-        let mut serializer = try!(self.serialize_map(iterator_len_hint(&iter)));
+        let mut serializer = tri!(self.serialize_map(iterator_len_hint(&iter)));
-
+        tri!(iter.try_for_each(|(key, value)| serializer.serialize_entry(&key, &value)));
-        #[cfg(not(no_iterator_try_fold))]
-        {
-            let mut iter = iter;
-            try!(iter.try_for_each(|(key, value)| serializer.serialize_entry(&key, &value)));
-        }
-
-        #[cfg(no_iterator_try_fold)]
-        {
-            for (key, value) in iter {
-                try!(serializer.serialize_entry(&key, &value));
-            }
-        }
-
         serializer.end()
     }
 
@@ -1839,7 +1813,7 @@ pub trait SerializeMap {
         K: Serialize,
         V: Serialize,
     {
-        try!(self.serialize_key(key));
+        tri!(self.serialize_key(key));
         self.serialize_value(value)
     }
 

serde/src/std_error.rs

@@ -1,4 +1,4 @@
-use lib::{Debug, Display};
+use crate::lib::{Debug, Display};
 
 /// Either a re-export of std::error::Error or a new identical trait, depending
 /// on whether Serde's "std" feature is enabled.

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.178" # remember to update html_root_url
+version = "1.0.183" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 categories = ["no-std", "no-std::no-alloc"]
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -23,7 +23,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = "2.0.25"
+syn = "2.0.28"
 
 [dev-dependencies]
 serde = { version = "1", path = "../serde" }

serde_derive/src/de.rs

@@ -324,10 +324,10 @@ fn deserialize_in_place_body(cont: &Container, params: &Parameters) -> Option<St
 
     let code = match &cont.data {
         Data::Struct(Style::Struct, fields) => {
-            deserialize_struct_in_place(None, params, fields, &cont.attrs, None)?
+            deserialize_struct_in_place(params, fields, &cont.attrs)?
         }
         Data::Struct(Style::Tuple, fields) | Data::Struct(Style::Newtype, fields) => {
-            deserialize_tuple_in_place(None, params, fields, &cont.attrs, None)
+            deserialize_tuple_in_place(params, fields, &cont.attrs)
         }
         Data::Enum(_) | Data::Struct(Style::Unit, _) => {
             return None;
@@ -582,11 +582,9 @@ fn deserialize_tuple(
 
 #[cfg(feature = "deserialize_in_place")]
 fn deserialize_tuple_in_place(
-    variant_ident: Option<syn::Ident>,
     params: &Parameters,
     fields: &[Field],
     cattrs: &attr::Container,
-    deserializer: Option<TokenStream>,
 ) -> Fragment {
     assert!(!cattrs.has_flatten());
 
@@ -600,17 +598,25 @@ fn deserialize_tuple_in_place(
         split_with_de_lifetime(params);
     let delife = params.borrowed.de_lifetime();
 
-    let is_enum = variant_ident.is_some();
+    let expecting = format!("tuple struct {}", params.type_name());
-    let expecting = match variant_ident {
-        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();
 
-    let visit_newtype_struct = if !is_enum && nfields == 1 {
+    let visit_newtype_struct = if nfields == 1 {
-        Some(deserialize_newtype_struct_in_place(params, &fields[0]))
+        // We do not generate deserialize_in_place if every field has a
+        // deserialize_with.
+        assert!(fields[0].attrs.deserialize_with().is_none());
+
+        Some(quote! {
+            #[inline]
+            fn visit_newtype_struct<__E>(self, __e: __E) -> _serde::__private::Result<Self::Value, __E::Error>
+            where
+                __E: _serde::Deserializer<#delife>,
+            {
+                _serde::Deserialize::deserialize_in_place(__e, &mut self.place.0)
+            }
+        })
     } else {
         None
     };
@@ -624,15 +630,10 @@ fn deserialize_tuple_in_place(
         }
     };
 
-    let dispatch = if let Some(deserializer) = deserializer {
+    let type_name = cattrs.name().deserialize_name();
-        quote!(_serde::Deserializer::deserialize_tuple(#deserializer, #field_count, #visitor_expr))
+    let dispatch = if nfields == 1 {
-    } else if is_enum {
-        quote!(_serde::de::VariantAccess::tuple_variant(__variant, #field_count, #visitor_expr))
-    } else if nfields == 1 {
-        let type_name = cattrs.name().deserialize_name();
         quote!(_serde::Deserializer::deserialize_newtype_struct(__deserializer, #type_name, #visitor_expr))
     } else {
-        let type_name = cattrs.name().deserialize_name();
         quote!(_serde::Deserializer::deserialize_tuple_struct(__deserializer, #type_name, #field_count, #visitor_expr))
     };
 
@@ -722,19 +723,11 @@ fn deserialize_seq(
                     })
                 }
             };
-            let value_if_none = match field.attrs.default() {
+            let value_if_none = expr_is_missing_seq(None, index_in_seq, field, cattrs, expecting);
-                attr::Default::Default => quote!(_serde::__private::Default::default()),
-                attr::Default::Path(path) => quote!(#path()),
-                attr::Default::None => quote!(
-                    return _serde::__private::Err(_serde::de::Error::invalid_length(#index_in_seq, &#expecting));
-                ),
-            };
             let assign = quote! {
                 let #var = match #visit {
                     _serde::__private::Some(__value) => __value,
-                    _serde::__private::None => {
+                    _serde::__private::None => #value_if_none,
-                        #value_if_none
-                    }
                 };
             };
             index_in_seq += 1;
@@ -810,24 +803,14 @@ fn deserialize_seq_in_place(
                 self.place.#member = #default;
             }
         } else {
-            let value_if_none = match field.attrs.default() {
+            let value_if_none = expr_is_missing_seq(Some(quote!(self.place.#member = )), index_in_seq, field, cattrs, expecting);
-                attr::Default::Default => quote!(
-                    self.place.#member = _serde::__private::Default::default();
-                ),
-                attr::Default::Path(path) => quote!(
-                    self.place.#member = #path();
-                ),
-                attr::Default::None => quote!(
-                    return _serde::__private::Err(_serde::de::Error::invalid_length(#index_in_seq, &#expecting));
-                ),
-            };
             let write = match field.attrs.deserialize_with() {
                 None => {
                     quote! {
                         if let _serde::__private::None = _serde::de::SeqAccess::next_element_seed(&mut __seq,
                             _serde::__private::de::InPlaceSeed(&mut self.place.#member))?
                         {
-                            #value_if_none
+                            #value_if_none;
                         }
                     }
                 }
@@ -840,7 +823,7 @@ fn deserialize_seq_in_place(
                                 self.place.#member = __wrap.value;
                             }
                             _serde::__private::None => {
-                                #value_if_none
+                                #value_if_none;
                             }
                         }
                     })
@@ -918,25 +901,6 @@ fn deserialize_newtype_struct(
     }
 }
 
-#[cfg(feature = "deserialize_in_place")]
-fn deserialize_newtype_struct_in_place(params: &Parameters, field: &Field) -> TokenStream {
-    // We do not generate deserialize_in_place if every field has a
-    // deserialize_with.
-    assert!(field.attrs.deserialize_with().is_none());
-
-    let delife = params.borrowed.de_lifetime();
-
-    quote! {
-        #[inline]
-        fn visit_newtype_struct<__E>(self, __e: __E) -> _serde::__private::Result<Self::Value, __E::Error>
-        where
-            __E: _serde::Deserializer<#delife>,
-        {
-            _serde::Deserialize::deserialize_in_place(__e, &mut self.place.0)
-        }
-    }
-}
-
 enum StructForm<'a> {
     Struct,
     /// Contains a variant name
@@ -1001,12 +965,7 @@ fn deserialize_struct(
             )
         })
         .collect();
-    let field_visitor = Stmts(deserialize_generated_identifier(
+    let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs);
-        &field_names_idents,
-        cattrs,
-        false,
-        None,
-    ));
 
     // untagged struct variants do not get a visit_seq method. The same applies to
     // structs that only have a map representation.
@@ -1058,7 +1017,7 @@ fn deserialize_struct(
     } else {
         let field_names = field_names_idents
             .iter()
-            .flat_map(|(_, _, aliases)| aliases);
+            .flat_map(|&(_, _, aliases)| aliases);
 
         Some(quote! {
             #[doc(hidden)]
@@ -1133,14 +1092,10 @@ fn deserialize_struct(
 
 #[cfg(feature = "deserialize_in_place")]
 fn deserialize_struct_in_place(
-    variant_ident: Option<syn::Ident>,
     params: &Parameters,
     fields: &[Field],
     cattrs: &attr::Container,
-    deserializer: Option<TokenStream>,
 ) -> Option<Fragment> {
-    let is_enum = variant_ident.is_some();
-
     // for now we do not support in_place deserialization for structs that
     // are represented as map.
     if cattrs.has_flatten() {
@@ -1152,58 +1107,35 @@ fn deserialize_struct_in_place(
         split_with_de_lifetime(params);
     let delife = params.borrowed.de_lifetime();
 
-    let expecting = match variant_ident {
+    let expecting = format!("struct {}", params.type_name());
-        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));
+    let field_names_idents: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .filter(|&(_, field)| !field.attrs.skip_deserializing())
+        .map(|(i, field)| {
+            (
+                field.attrs.name().deserialize_name(),
+                field_i(i),
+                field.attrs.aliases(),
+            )
+        })
+        .collect();
 
-    let (field_visitor, fields_stmt, visit_map) =
+    let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs);
-        deserialize_struct_as_struct_in_place_visitor(params, fields, cattrs);
 
-    let field_visitor = Stmts(field_visitor);
+    let mut_seq = if field_names_idents.is_empty() {
-    let fields_stmt = Stmts(fields_stmt);
-    let visit_map = Stmts(visit_map);
-
-    let visitor_expr = quote! {
-        __Visitor {
-            place: __place,
-            lifetime: _serde::__private::PhantomData,
-        }
-    };
-    let dispatch = if let Some(deserializer) = deserializer {
-        quote! {
-            _serde::Deserializer::deserialize_any(#deserializer, #visitor_expr)
-        }
-    } else if is_enum {
-        quote! {
-            _serde::de::VariantAccess::struct_variant(__variant, FIELDS, #visitor_expr)
-        }
-    } else {
-        let type_name = cattrs.name().deserialize_name();
-        quote! {
-            _serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, #visitor_expr)
-        }
-    };
-
-    let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
-    let visitor_var = if all_skipped {
         quote!(_)
     } else {
         quote!(mut __seq)
     };
-
+    let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
-    let visit_seq = quote! {
+    let visit_map = Stmts(deserialize_map_in_place(params, fields, cattrs));
-        #[inline]
+    let field_names = field_names_idents
-        fn visit_seq<__A>(self, #visitor_var: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+        .iter()
-        where
+        .flat_map(|&(_, _, aliases)| aliases);
-            __A: _serde::de::SeqAccess<#delife>,
+    let type_name = cattrs.name().deserialize_name();
-        {
-            #visit_seq
-        }
-    };
 
     let in_place_impl_generics = de_impl_generics.in_place();
     let in_place_ty_generics = de_ty_generics.in_place();
@@ -1225,7 +1157,13 @@ fn deserialize_struct_in_place(
                 _serde::__private::Formatter::write_str(__formatter, #expecting)
             }
 
-            #visit_seq
+            #[inline]
+            fn visit_seq<__A>(self, #mut_seq: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::SeqAccess<#delife>,
+            {
+                #visit_seq
+            }
 
             #[inline]
             fn visit_map<__A>(self, mut __map: __A) -> _serde::__private::Result<Self::Value, __A::Error>
@@ -1236,9 +1174,13 @@ fn deserialize_struct_in_place(
             }
         }
 
-        #fields_stmt
+        #[doc(hidden)]
+        const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
 
-        #dispatch
+        _serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, __Visitor {
+            place: __place,
+            lifetime: _serde::__private::PhantomData,
+        })
     })
 }
 
@@ -1295,7 +1237,12 @@ fn prepare_enum_variant_enum(
         })
         .collect();
 
-    let other_idx = deserialized_variants.position(|(_, variant)| variant.attrs.other());
+    let fallthrough = deserialized_variants
+        .position(|(_, variant)| variant.attrs.other())
+        .map(|other_idx| {
+            let ignore_variant = variant_names_idents[other_idx].1.clone();
+            quote!(_serde::__private::Ok(__Field::#ignore_variant))
+        });
 
     let variants_stmt = {
         let variant_names = variant_names_idents.iter().map(|(name, _, _)| name);
@@ -1309,7 +1256,8 @@ fn prepare_enum_variant_enum(
         &variant_names_idents,
         cattrs,
         true,
-        other_idx,
+        None,
+        fallthrough,
     ));
 
     (variants_stmt, variant_visitor)
@@ -1490,7 +1438,8 @@ fn deserialize_adjacently_tagged_enum(
         })
         .collect();
 
-    let expecting = format!("adjacently tagged enum {}", params.type_name());
+    let rust_name = params.type_name();
+    let expecting = format!("adjacently tagged enum {}", rust_name);
     let expecting = cattrs.expecting().unwrap_or(&expecting);
     let type_name = cattrs.name().deserialize_name();
     let deny_unknown_fields = cattrs.deny_unknown_fields();
@@ -1510,6 +1459,14 @@ fn deserialize_adjacently_tagged_enum(
         }
     };
 
+    let variant_seed = quote! {
+        _serde::__private::de::AdjacentlyTaggedEnumVariantSeed::<__Field> {
+            enum_name: #rust_name,
+            variants: VARIANTS,
+            fields_enum: _serde::__private::PhantomData
+        }
+    };
+
     let mut missing_content = quote! {
         _serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#content))
     };
@@ -1557,6 +1514,10 @@ fn deserialize_adjacently_tagged_enum(
         _serde::de::MapAccess::next_key_seed(&mut __map, #tag_or_content)?
     };
 
+    let variant_from_map = quote! {
+        _serde::de::MapAccess::next_value_seed(&mut __map, #variant_seed)?
+    };
+
     // When allowing unknown fields, we want to transparently step through keys
     // we don't care about until we find `tag`, `content`, or run out of keys.
     let next_relevant_key = if deny_unknown_fields {
@@ -1602,11 +1563,11 @@ fn deserialize_adjacently_tagged_enum(
 
     let finish_content_then_tag = if variant_arms.is_empty() {
         quote! {
-            match _serde::de::MapAccess::next_value::<__Field>(&mut __map)? {}
+            match #variant_from_map {}
         }
     } else {
         quote! {
-            let __ret = match _serde::de::MapAccess::next_value(&mut __map)? {
+            let __ret = match #variant_from_map {
                 // Deserialize the buffered content now that we know the variant.
                 #(#variant_arms)*
             }?;
@@ -1662,7 +1623,7 @@ fn deserialize_adjacently_tagged_enum(
                     // First key is the tag.
                     _serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
                         // Parse the tag.
-                        let __field = _serde::de::MapAccess::next_value(&mut __map)?;
+                        let __field = #variant_from_map;
                         // Visit the second key.
                         match #next_relevant_key {
                             // Second key is a duplicate of the tag.
@@ -2018,30 +1979,15 @@ fn deserialize_untagged_newtype_variant(
 }
 
 fn deserialize_generated_identifier(
-    fields: &[(String, Ident, Vec<String>)],
+    fields: &[(&str, Ident, &BTreeSet<String>)],
     cattrs: &attr::Container,
     is_variant: bool,
-    other_idx: Option<usize>,
+    ignore_variant: Option<TokenStream>,
+    fallthrough: Option<TokenStream>,
 ) -> Fragment {
     let this_value = quote!(__Field);
     let field_idents: &Vec<_> = &fields.iter().map(|(_, ident, _)| ident).collect();
 
-    let (ignore_variant, fallthrough) = if !is_variant && cattrs.has_flatten() {
-        let ignore_variant = quote!(__other(_serde::__private::de::Content<'de>),);
-        let fallthrough = quote!(_serde::__private::Ok(__Field::__other(__value)));
-        (Some(ignore_variant), Some(fallthrough))
-    } else if let Some(other_idx) = other_idx {
-        let ignore_variant = fields[other_idx].1.clone();
-        let fallthrough = quote!(_serde::__private::Ok(__Field::#ignore_variant));
-        (None, Some(fallthrough))
-    } else if is_variant || cattrs.deny_unknown_fields() {
-        (None, None)
-    } else {
-        let ignore_variant = quote!(__ignore,);
-        let fallthrough = quote!(_serde::__private::Ok(__Field::__ignore));
-        (Some(ignore_variant), Some(fallthrough))
-    };
-
     let visitor_impl = Stmts(deserialize_identifier(
         &this_value,
         fields,
@@ -2087,6 +2033,33 @@ fn deserialize_generated_identifier(
     }
 }
 
+/// Generates enum and its `Deserialize` implementation that represents each
+/// non-skipped field of the struct
+fn deserialize_field_identifier(
+    fields: &[(&str, Ident, &BTreeSet<String>)],
+    cattrs: &attr::Container,
+) -> Stmts {
+    let (ignore_variant, fallthrough) = if cattrs.has_flatten() {
+        let ignore_variant = quote!(__other(_serde::__private::de::Content<'de>),);
+        let fallthrough = quote!(_serde::__private::Ok(__Field::__other(__value)));
+        (Some(ignore_variant), Some(fallthrough))
+    } else if cattrs.deny_unknown_fields() {
+        (None, None)
+    } else {
+        let ignore_variant = quote!(__ignore,);
+        let fallthrough = quote!(_serde::__private::Ok(__Field::__ignore));
+        (Some(ignore_variant), Some(fallthrough))
+    };
+
+    Stmts(deserialize_generated_identifier(
+        fields,
+        cattrs,
+        false,
+        ignore_variant,
+        fallthrough,
+    ))
+}
+
 // Generates `Deserialize::deserialize` body for an enum with
 // `serde(field_identifier)` or `serde(variant_identifier)` attribute.
 fn deserialize_custom_identifier(
@@ -2148,7 +2121,7 @@ fn deserialize_custom_identifier(
         })
         .collect();
 
-    let names = names_idents.iter().map(|(name, _, _)| name);
+    let names = names_idents.iter().flat_map(|&(_, _, aliases)| aliases);
 
     let names_const = if fallthrough.is_some() {
         None
@@ -2204,32 +2177,24 @@ fn deserialize_custom_identifier(
 
 fn deserialize_identifier(
     this_value: &TokenStream,
-    fields: &[(String, Ident, Vec<String>)],
+    fields: &[(&str, Ident, &BTreeSet<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();
+    let str_mapping = fields.iter().map(|(_, ident, aliases)| {
-    for (_, ident, aliases) in fields {
+        // `aliases` also contains a main name
-        flat_fields.extend(aliases.iter().map(|alias| (alias, ident)));
+        quote!(#(#aliases)|* => _serde::__private::Ok(#this_value::#ident))
-    }
+    });
-
+    let bytes_mapping = fields.iter().map(|(_, ident, aliases)| {
-    let field_strs: &Vec<_> = &flat_fields.iter().map(|(name, _)| name).collect();
+        // `aliases` also contains a main name
-    let field_bytes: &Vec<_> = &flat_fields
+        let aliases = aliases
-        .iter()
+            .iter()
-        .map(|(name, _)| Literal::byte_string(name.as_bytes()))
+            .map(|alias| Literal::byte_string(alias.as_bytes()));
-        .collect();
+        quote!(#(#aliases)|* => _serde::__private::Ok(#this_value::#ident))
-
+    });
-    let constructors: &Vec<_> = &flat_fields
-        .iter()
-        .map(|(_, ident)| quote!(#this_value::#ident))
-        .collect();
-    let main_constructors: &Vec<_> = &fields
-        .iter()
-        .map(|(_, ident, _)| quote!(#this_value::#ident))
-        .collect();
 
     let expecting = expecting.unwrap_or(if is_variant {
         "variant identifier"
@@ -2237,8 +2202,6 @@ fn deserialize_identifier(
         "field identifier"
     });
 
-    let index_expecting = if is_variant { "variant" } else { "field" };
-
     let bytes_to_str = if fallthrough.is_some() || collect_other_fields {
         None
     } else {
@@ -2286,21 +2249,6 @@ fn deserialize_identifier(
         &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 visit_other = if collect_other_fields {
         quote! {
             fn visit_bool<__E>(self, __value: bool) -> _serde::__private::Result<Self::Value, __E>
@@ -2395,15 +2343,33 @@ fn deserialize_identifier(
             }
         }
     } else {
+        let u64_mapping = fields.iter().enumerate().map(|(i, (_, ident, _))| {
+            let i = i as u64;
+            quote!(#i => _serde::__private::Ok(#this_value::#ident))
+        });
+
+        let u64_fallthrough_arm_tokens;
+        let u64_fallthrough_arm = if let Some(fallthrough) = &fallthrough {
+            fallthrough
+        } else {
+            let index_expecting = if is_variant { "variant" } else { "field" };
+            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
+        };
+
         quote! {
             fn visit_u64<__E>(self, __value: u64) -> _serde::__private::Result<Self::Value, __E>
             where
                 __E: _serde::de::Error,
             {
                 match __value {
-                    #(
+                    #(#u64_mapping,)*
-                        #variant_indices => _serde::__private::Ok(#main_constructors),
-                    )*
                     _ => #u64_fallthrough_arm,
                 }
             }
@@ -2411,6 +2377,8 @@ fn deserialize_identifier(
     };
 
     let visit_borrowed = if fallthrough_borrowed.is_some() || collect_other_fields {
+        let str_mapping = str_mapping.clone();
+        let bytes_mapping = bytes_mapping.clone();
         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>
@@ -2418,9 +2386,7 @@ fn deserialize_identifier(
                 __E: _serde::de::Error,
             {
                 match __value {
-                    #(
+                    #(#str_mapping,)*
-                        #field_strs => _serde::__private::Ok(#constructors),
-                    )*
                     _ => {
                         #value_as_borrowed_str_content
                         #fallthrough_borrowed_arm
@@ -2433,9 +2399,7 @@ fn deserialize_identifier(
                 __E: _serde::de::Error,
             {
                 match __value {
-                    #(
+                    #(#bytes_mapping,)*
-                        #field_bytes => _serde::__private::Ok(#constructors),
-                    )*
                     _ => {
                         #bytes_to_str
                         #value_as_borrowed_bytes_content
@@ -2460,9 +2424,7 @@ fn deserialize_identifier(
             __E: _serde::de::Error,
         {
             match __value {
-                #(
+                #(#str_mapping,)*
-                    #field_strs => _serde::__private::Ok(#constructors),
-                )*
                 _ => {
                     #value_as_str_content
                     #fallthrough_arm
@@ -2475,9 +2437,7 @@ fn deserialize_identifier(
             __E: _serde::de::Error,
         {
             match __value {
-                #(
+                #(#bytes_mapping,)*
-                    #field_bytes => _serde::__private::Ok(#constructors),
-                )*
                 _ => {
                     #bytes_to_str
                     #value_as_bytes_content
@@ -2707,42 +2667,6 @@ fn deserialize_map(
     }
 }
 
-#[cfg(feature = "deserialize_in_place")]
-fn deserialize_struct_as_struct_in_place_visitor(
-    params: &Parameters,
-    fields: &[Field],
-    cattrs: &attr::Container,
-) -> (Fragment, Fragment, Fragment) {
-    assert!(!cattrs.has_flatten());
-
-    let field_names_idents: Vec<_> = fields
-        .iter()
-        .enumerate()
-        .filter(|&(_, field)| !field.attrs.skip_deserializing())
-        .map(|(i, field)| {
-            (
-                field.attrs.name().deserialize_name(),
-                field_i(i),
-                field.attrs.aliases(),
-            )
-        })
-        .collect();
-
-    let fields_stmt = {
-        let field_names = field_names_idents.iter().map(|(name, _, _)| name);
-        quote_block! {
-            #[doc(hidden)]
-            const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
-        }
-    };
-
-    let field_visitor = deserialize_generated_identifier(&field_names_idents, cattrs, false, None);
-
-    let visit_map = deserialize_map_in_place(params, fields, cattrs);
-
-    (field_visitor, fields_stmt, visit_map)
-}
-
 #[cfg(feature = "deserialize_in_place")]
 fn deserialize_map_in_place(
     params: &Parameters,
@@ -3046,6 +2970,35 @@ fn expr_is_missing(field: &Field, cattrs: &attr::Container) -> Fragment {
     }
 }
 
+fn expr_is_missing_seq(
+    assign_to: Option<TokenStream>,
+    index: usize,
+    field: &Field,
+    cattrs: &attr::Container,
+    expecting: &str,
+) -> TokenStream {
+    match field.attrs.default() {
+        attr::Default::Default => {
+            let span = field.original.span();
+            return quote_spanned!(span=> #assign_to _serde::__private::Default::default());
+        }
+        attr::Default::Path(path) => {
+            return quote_spanned!(path.span()=> #assign_to #path());
+        }
+        attr::Default::None => { /* below */ }
+    }
+
+    match *cattrs.default() {
+        attr::Default::Default | attr::Default::Path(_) => {
+            let member = &field.member;
+            quote!(#assign_to __default.#member)
+        }
+        attr::Default::None => quote!(
+            return _serde::__private::Err(_serde::de::Error::invalid_length(#index, &#expecting))
+        ),
+    }
+}
+
 fn effective_style(variant: &Variant) -> Style {
     match variant.style {
         Style::Newtype if variant.fields[0].attrs.skip_deserializing() => Style::Unit,

serde_derive/src/internals/attr.rs

@@ -134,7 +134,7 @@ pub struct Name {
     serialize_renamed: bool,
     deserialize: String,
     deserialize_renamed: bool,
-    deserialize_aliases: Vec<String>,
+    deserialize_aliases: BTreeSet<String>,
 }
 
 fn unraw(ident: &Ident) -> String {
@@ -148,16 +148,12 @@ impl Name {
         de_name: Attr<String>,
         de_aliases: Option<VecAttr<String>>,
     ) -> Name {
-        let deserialize_aliases = match de_aliases {
+        let mut alias_set = BTreeSet::new();
-            Some(de_aliases) => {
+        if let Some(de_aliases) = de_aliases {
-                let mut alias_list = BTreeSet::new();
+            for alias_name in de_aliases.get() {
-                for alias_name in de_aliases.get() {
+                alias_set.insert(alias_name);
-                    alias_list.insert(alias_name);
-                }
-                alias_list.into_iter().collect()
             }
-            None => Vec::new(),
+        }
-        };
 
         let ser_name = ser_name.get();
         let ser_renamed = ser_name.is_some();
@@ -168,27 +164,22 @@ impl Name {
             serialize_renamed: ser_renamed,
             deserialize: de_name.unwrap_or(source_name),
             deserialize_renamed: de_renamed,
-            deserialize_aliases,
+            deserialize_aliases: alias_set,
         }
     }
 
     /// Return the container name for the container when serializing.
-    pub fn serialize_name(&self) -> String {
+    pub fn serialize_name(&self) -> &str {
-        self.serialize.clone()
+        &self.serialize
     }
 
     /// Return the container name for the container when deserializing.
-    pub fn deserialize_name(&self) -> String {
+    pub fn deserialize_name(&self) -> &str {
-        self.deserialize.clone()
+        &self.deserialize
     }
 
-    fn deserialize_aliases(&self) -> Vec<String> {
+    fn deserialize_aliases(&self) -> &BTreeSet<String> {
-        let mut aliases = self.deserialize_aliases.clone();
+        &self.deserialize_aliases
-        let main_name = self.deserialize_name();
-        if !aliases.contains(&main_name) {
-            aliases.push(main_name);
-        }
-        aliases
     }
 }
 
@@ -405,20 +396,20 @@ impl Container {
                         if let Some(path) = parse_lit_into_expr_path(cx, DEFAULT, &meta)? {
                             match &item.data {
                                 syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
-                                    syn::Fields::Named(_) => {
+                                    syn::Fields::Named(_) | syn::Fields::Unnamed(_) => {
                                         default.set(&meta.path, Default::Path(path));
                                     }
-                                    syn::Fields::Unnamed(_) | syn::Fields::Unit => {
+                                    syn::Fields::Unit => {
-                                        let msg = "#[serde(default = \"...\")] can only be used on structs with named fields";
+                                        let msg = "#[serde(default = \"...\")] can only be used on structs that have fields";
                                         cx.syn_error(meta.error(msg));
                                     }
                                 },
                                 syn::Data::Enum(_) => {
-                                    let msg = "#[serde(default = \"...\")] can only be used on structs with named fields";
+                                    let msg = "#[serde(default = \"...\")] can only be used on structs";
                                     cx.syn_error(meta.error(msg));
                                 }
                                 syn::Data::Union(_) => {
-                                    let msg = "#[serde(default = \"...\")] can only be used on structs with named fields";
+                                    let msg = "#[serde(default = \"...\")] can only be used on structs";
                                     cx.syn_error(meta.error(msg));
                                 }
                             }
@@ -427,20 +418,20 @@ impl Container {
                         // #[serde(default)]
                         match &item.data {
                             syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
-                                syn::Fields::Named(_) => {
+                                syn::Fields::Named(_) | syn::Fields::Unnamed(_) => {
                                     default.set(meta.path, Default::Default);
                                 }
-                                syn::Fields::Unnamed(_) | syn::Fields::Unit => {
+                                syn::Fields::Unit => {
-                                    let msg = "#[serde(default)] can only be used on structs with named fields";
+                                    let msg = "#[serde(default)] can only be used on structs that have fields";
                                     cx.error_spanned_by(fields, msg);
                                 }
                             },
                             syn::Data::Enum(_) => {
-                                let msg = "#[serde(default)] can only be used on structs with named fields";
+                                let msg = "#[serde(default)] can only be used on structs";
                                 cx.syn_error(meta.error(msg));
                             }
                             syn::Data::Union(_) => {
-                                let msg = "#[serde(default)] can only be used on structs with named fields";
+                                let msg = "#[serde(default)] can only be used on structs";
                                 cx.syn_error(meta.error(msg));
                             }
                         }
@@ -977,7 +968,7 @@ impl Variant {
         &self.name
     }
 
-    pub fn aliases(&self) -> Vec<String> {
+    pub fn aliases(&self) -> &BTreeSet<String> {
         self.name.deserialize_aliases()
     }
 
@@ -988,6 +979,9 @@ impl Variant {
         if !self.name.deserialize_renamed {
             self.name.deserialize = rules.deserialize.apply_to_variant(&self.name.deserialize);
         }
+        self.name
+            .deserialize_aliases
+            .insert(self.name.deserialize.clone());
     }
 
     pub fn rename_all_rules(&self) -> RenameAllRules {
@@ -1316,7 +1310,7 @@ impl Field {
         &self.name
     }
 
-    pub fn aliases(&self) -> Vec<String> {
+    pub fn aliases(&self) -> &BTreeSet<String> {
         self.name.deserialize_aliases()
     }
 
@@ -1327,6 +1321,9 @@ impl Field {
         if !self.name.deserialize_renamed {
             self.name.deserialize = rules.deserialize.apply_to_field(&self.name.deserialize);
         }
+        self.name
+            .deserialize_aliases
+            .insert(self.name.deserialize.clone());
     }
 
     pub fn skip_serializing(&self) -> bool {

serde_derive/src/internals/check.rs

@@ -1,11 +1,12 @@
 use crate::internals::ast::{Container, Data, Field, Style};
-use crate::internals::attr::{Identifier, TagType};
+use crate::internals::attr::{Default, Identifier, TagType};
 use crate::internals::{ungroup, 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: &mut Container, derive: Derive) {
+    check_default_on_tuple(cx, cont);
     check_remote_generic(cx, cont);
     check_getter(cx, cont);
     check_flatten(cx, cont);
@@ -17,6 +18,39 @@ pub fn check(cx: &Ctxt, cont: &mut Container, derive: Derive) {
     check_from_and_try_from(cx, cont);
 }
 
+// If some field of a tuple struct is marked #[serde(default)] then all fields
+// after it must also be marked with that attribute, or the struct must have a
+// container-level serde(default) attribute. A field's default value is only
+// used for tuple fields if the sequence is exhausted at that point; that means
+// all subsequent fields will fail to deserialize if they don't have their own
+// default.
+fn check_default_on_tuple(cx: &Ctxt, cont: &Container) {
+    if let Default::None = cont.attrs.default() {
+        if let Data::Struct(Style::Tuple, fields) = &cont.data {
+            let mut first_default_index = None;
+            for (i, field) in fields.iter().enumerate() {
+                // Skipped fields automatically get the #[serde(default)]
+                // attribute. We are interested only on non-skipped fields here.
+                if field.attrs.skip_deserializing() {
+                    continue;
+                }
+                if let Default::None = field.attrs.default() {
+                    if let Some(first) = first_default_index {
+                        cx.error_spanned_by(
+                            field.ty,
+                            format!("field must have #[serde(default)] because previous field {} has #[serde(default)]", first),
+                        );
+                    }
+                    continue;
+                }
+                if first_default_index.is_none() {
+                    first_default_index = Some(i);
+                }
+            }
+        }
+    }
+}
+
 // Remote derive definition type must have either all of the generics of the
 // remote type:
 //

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/1.0.178")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.183")]
 // Ignored clippy lints
 #![allow(
     // clippy false positive: https://github.com/rust-lang/rust-clippy/issues/7054

serde_derive/src/ser.rs

@@ -478,7 +478,14 @@ fn serialize_variant(
                 serialize_internally_tagged_variant(params, variant, cattrs, tag)
             }
             (attr::TagType::Adjacent { tag, content }, false) => {
-                serialize_adjacently_tagged_variant(params, variant, cattrs, tag, content)
+                serialize_adjacently_tagged_variant(
+                    params,
+                    variant,
+                    cattrs,
+                    variant_index,
+                    tag,
+                    content,
+                )
             }
             (attr::TagType::None, _) | (_, true) => {
                 serialize_untagged_variant(params, variant, cattrs)
@@ -559,7 +566,7 @@ fn serialize_externally_tagged_variant(
             },
             params,
             &variant.fields,
-            &type_name,
+            type_name,
         ),
     }
 }
@@ -624,7 +631,7 @@ fn serialize_internally_tagged_variant(
             StructVariant::InternallyTagged { tag, variant_name },
             params,
             &variant.fields,
-            &type_name,
+            type_name,
         ),
         Style::Tuple => unreachable!("checked in serde_derive_internals"),
     }
@@ -634,12 +641,20 @@ fn serialize_adjacently_tagged_variant(
     params: &Parameters,
     variant: &Variant,
     cattrs: &attr::Container,
+    variant_index: u32,
     tag: &str,
     content: &str,
 ) -> Fragment {
     let this_type = &params.this_type;
     let type_name = cattrs.name().serialize_name();
     let variant_name = variant.attrs.name().serialize_name();
+    let serialize_variant = quote! {
+        &_serde::__private::ser::AdjacentlyTaggedEnumVariant {
+            enum_name: #type_name,
+            variant_index: #variant_index,
+            variant_name: #variant_name,
+        }
+    };
 
     let inner = Stmts(if let Some(path) = variant.attrs.serialize_with() {
         let ser = wrap_serialize_variant_with(params, path, variant);
@@ -653,7 +668,7 @@ fn serialize_adjacently_tagged_variant(
                     let mut __struct = _serde::Serializer::serialize_struct(
                         __serializer, #type_name, 1)?;
                     _serde::ser::SerializeStruct::serialize_field(
-                        &mut __struct, #tag, #variant_name)?;
+                        &mut __struct, #tag, #serialize_variant)?;
                     _serde::ser::SerializeStruct::end(__struct)
                 };
             }
@@ -670,7 +685,7 @@ fn serialize_adjacently_tagged_variant(
                     let mut __struct = _serde::Serializer::serialize_struct(
                         __serializer, #type_name, 2)?;
                     _serde::ser::SerializeStruct::serialize_field(
-                        &mut __struct, #tag, #variant_name)?;
+                        &mut __struct, #tag, #serialize_variant)?;
                     #func(
                         &mut __struct, #content, #field_expr)?;
                     _serde::ser::SerializeStruct::end(__struct)
@@ -683,7 +698,7 @@ fn serialize_adjacently_tagged_variant(
                 StructVariant::Untagged,
                 params,
                 &variant.fields,
-                &variant_name,
+                variant_name,
             ),
         }
     });
@@ -735,7 +750,7 @@ fn serialize_adjacently_tagged_variant(
         let mut __struct = _serde::Serializer::serialize_struct(
             __serializer, #type_name, 2)?;
         _serde::ser::SerializeStruct::serialize_field(
-            &mut __struct, #tag, #variant_name)?;
+            &mut __struct, #tag, #serialize_variant)?;
         _serde::ser::SerializeStruct::serialize_field(
             &mut __struct, #content, &__AdjacentlyTagged {
                 data: (#(#fields_ident,)*),
@@ -779,16 +794,16 @@ fn serialize_untagged_variant(
         Style::Tuple => serialize_tuple_variant(TupleVariant::Untagged, params, &variant.fields),
         Style::Struct => {
             let type_name = cattrs.name().serialize_name();
-            serialize_struct_variant(StructVariant::Untagged, params, &variant.fields, &type_name)
+            serialize_struct_variant(StructVariant::Untagged, params, &variant.fields, type_name)
         }
     }
 }
 
-enum TupleVariant {
+enum TupleVariant<'a> {
     ExternallyTagged {
-        type_name: String,
+        type_name: &'a str,
         variant_index: u32,
-        variant_name: String,
+        variant_name: &'a str,
     },
     Untagged,
 }
@@ -855,11 +870,11 @@ fn serialize_tuple_variant(
 enum StructVariant<'a> {
     ExternallyTagged {
         variant_index: u32,
-        variant_name: String,
+        variant_name: &'a str,
     },
     InternallyTagged {
         tag: &'a str,
-        variant_name: String,
+        variant_name: &'a str,
     },
     Untagged,
 }

serde_derive_internals/Cargo.toml

@@ -17,7 +17,7 @@ path = "lib.rs"
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "2.0.25", default-features = false, features = ["clone-impls", "derive", "parsing", "printing"] }
+syn = { version = "2.0.28", default-features = false, features = ["clone-impls", "derive", "parsing", "printing"] }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]

test_suite/no_std/src/main.rs

@@ -1,3 +1,4 @@
+#![allow(internal_features)]
 #![feature(lang_items, start)]
 #![no_std]
 

test_suite/tests/test_annotations.rs

@@ -114,42 +114,6 @@ struct CollectOther {
     extra: HashMap<String, u32>,
 }
 
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
-struct FlattenStructEnumWrapper {
-    #[serde(flatten)]
-    data: FlattenStructEnum,
-    #[serde(flatten)]
-    extra: HashMap<String, String>,
-}
-
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case")]
-enum FlattenStructEnum {
-    InsertInteger { index: u32, value: u32 },
-}
-
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
-struct FlattenStructTagContentEnumWrapper {
-    outer: u32,
-    #[serde(flatten)]
-    data: FlattenStructTagContentEnumNewtype,
-}
-
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
-struct FlattenStructTagContentEnumNewtype(pub FlattenStructTagContentEnum);
-
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case", tag = "type", content = "value")]
-enum FlattenStructTagContentEnum {
-    InsertInteger { index: u32, value: u32 },
-    NewtypeVariant(FlattenStructTagContentEnumNewtypeVariant),
-}
-
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
-struct FlattenStructTagContentEnumNewtypeVariant {
-    value: u32,
-}
-
 #[test]
 fn test_default_struct() {
     assert_de_tokens(
@@ -641,7 +605,7 @@ fn test_unknown_field_rename_struct() {
             Token::Str("a4"),
             Token::I32(3),
         ],
-        "unknown field `a4`, expected one of `a1`, `a3`, `a2`, `a5`, `a6`",
+        "unknown field `a4`, expected one of `a1`, `a2`, `a3`, `a5`, `a6`",
     );
 }
 
@@ -835,7 +799,7 @@ fn test_unknown_field_rename_enum() {
             Token::Str("d"),
             Token::I8(2),
         ],
-        "unknown field `d`, expected one of `a`, `c`, `b`, `e`, `f`",
+        "unknown field `d`, expected one of `a`, `b`, `c`, `e`, `f`",
     );
 }
 
@@ -1643,149 +1607,6 @@ fn test_collect_other() {
     );
 }
 
-#[test]
-fn test_flatten_struct_enum() {
-    let mut extra = HashMap::new();
-    extra.insert("extra_key".into(), "extra value".into());
-    let change_request = FlattenStructEnumWrapper {
-        data: FlattenStructEnum::InsertInteger {
-            index: 0,
-            value: 42,
-        },
-        extra,
-    };
-    assert_de_tokens(
-        &change_request,
-        &[
-            Token::Map { len: None },
-            Token::Str("insert_integer"),
-            Token::Map { len: None },
-            Token::Str("index"),
-            Token::U32(0),
-            Token::Str("value"),
-            Token::U32(42),
-            Token::MapEnd,
-            Token::Str("extra_key"),
-            Token::Str("extra value"),
-            Token::MapEnd,
-        ],
-    );
-    assert_ser_tokens(
-        &change_request,
-        &[
-            Token::Map { len: None },
-            Token::Str("insert_integer"),
-            Token::Struct {
-                len: 2,
-                name: "insert_integer",
-            },
-            Token::Str("index"),
-            Token::U32(0),
-            Token::Str("value"),
-            Token::U32(42),
-            Token::StructEnd,
-            Token::Str("extra_key"),
-            Token::Str("extra value"),
-            Token::MapEnd,
-        ],
-    );
-}
-
-#[test]
-fn test_flatten_struct_tag_content_enum() {
-    let change_request = FlattenStructTagContentEnumWrapper {
-        outer: 42,
-        data: FlattenStructTagContentEnumNewtype(FlattenStructTagContentEnum::InsertInteger {
-            index: 0,
-            value: 42,
-        }),
-    };
-    assert_de_tokens(
-        &change_request,
-        &[
-            Token::Map { len: None },
-            Token::Str("outer"),
-            Token::U32(42),
-            Token::Str("type"),
-            Token::Str("insert_integer"),
-            Token::Str("value"),
-            Token::Map { len: None },
-            Token::Str("index"),
-            Token::U32(0),
-            Token::Str("value"),
-            Token::U32(42),
-            Token::MapEnd,
-            Token::MapEnd,
-        ],
-    );
-    assert_ser_tokens(
-        &change_request,
-        &[
-            Token::Map { len: None },
-            Token::Str("outer"),
-            Token::U32(42),
-            Token::Str("type"),
-            Token::Str("insert_integer"),
-            Token::Str("value"),
-            Token::Struct {
-                len: 2,
-                name: "insert_integer",
-            },
-            Token::Str("index"),
-            Token::U32(0),
-            Token::Str("value"),
-            Token::U32(42),
-            Token::StructEnd,
-            Token::MapEnd,
-        ],
-    );
-}
-
-#[test]
-fn test_flatten_struct_tag_content_enum_newtype() {
-    let change_request = FlattenStructTagContentEnumWrapper {
-        outer: 42,
-        data: FlattenStructTagContentEnumNewtype(FlattenStructTagContentEnum::NewtypeVariant(
-            FlattenStructTagContentEnumNewtypeVariant { value: 23 },
-        )),
-    };
-    assert_de_tokens(
-        &change_request,
-        &[
-            Token::Map { len: None },
-            Token::Str("outer"),
-            Token::U32(42),
-            Token::Str("type"),
-            Token::Str("newtype_variant"),
-            Token::Str("value"),
-            Token::Map { len: None },
-            Token::Str("value"),
-            Token::U32(23),
-            Token::MapEnd,
-            Token::MapEnd,
-        ],
-    );
-    assert_ser_tokens(
-        &change_request,
-        &[
-            Token::Map { len: None },
-            Token::Str("outer"),
-            Token::U32(42),
-            Token::Str("type"),
-            Token::Str("newtype_variant"),
-            Token::Str("value"),
-            Token::Struct {
-                len: 1,
-                name: "FlattenStructTagContentEnumNewtypeVariant",
-            },
-            Token::Str("value"),
-            Token::U32(23),
-            Token::StructEnd,
-            Token::MapEnd,
-        ],
-    );
-}
-
 #[test]
 fn test_unknown_field_in_flatten() {
     #[derive(Debug, PartialEq, Serialize, Deserialize)]
@@ -2142,86 +1963,6 @@ fn test_lifetime_propagation_for_flatten() {
     );
 }
 
-#[test]
-fn test_flatten_enum_newtype() {
-    #[derive(Serialize, Deserialize, PartialEq, Debug)]
-    struct S {
-        #[serde(flatten)]
-        flat: E,
-    }
-
-    #[derive(Serialize, Deserialize, PartialEq, Debug)]
-    enum E {
-        Q(HashMap<String, String>),
-    }
-
-    let e = E::Q({
-        let mut map = HashMap::new();
-        map.insert("k".to_owned(), "v".to_owned());
-        map
-    });
-    let s = S { flat: e };
-
-    assert_tokens(
-        &s,
-        &[
-            Token::Map { len: None },
-            Token::Str("Q"),
-            Token::Map { len: Some(1) },
-            Token::Str("k"),
-            Token::Str("v"),
-            Token::MapEnd,
-            Token::MapEnd,
-        ],
-    );
-}
-
-#[test]
-fn test_flatten_internally_tagged() {
-    #[derive(Serialize, Deserialize, PartialEq, Debug)]
-    struct S {
-        #[serde(flatten)]
-        x: X,
-        #[serde(flatten)]
-        y: Y,
-    }
-
-    #[derive(Serialize, Deserialize, PartialEq, Debug)]
-    #[serde(tag = "typeX")]
-    enum X {
-        A { a: i32 },
-        B { b: i32 },
-    }
-
-    #[derive(Serialize, Deserialize, PartialEq, Debug)]
-    #[serde(tag = "typeY")]
-    enum Y {
-        C { c: i32 },
-        D { d: i32 },
-    }
-
-    let s = S {
-        x: X::B { b: 1 },
-        y: Y::D { d: 2 },
-    };
-
-    assert_tokens(
-        &s,
-        &[
-            Token::Map { len: None },
-            Token::Str("typeX"),
-            Token::Str("B"),
-            Token::Str("b"),
-            Token::I32(1),
-            Token::Str("typeY"),
-            Token::Str("D"),
-            Token::Str("d"),
-            Token::I32(2),
-            Token::MapEnd,
-        ],
-    );
-}
-
 #[test]
 fn test_externally_tagged_enum_containing_flatten() {
     #[derive(Serialize, Deserialize, PartialEq, Debug)]
@@ -2367,7 +2108,10 @@ fn test_adjacently_tagged_enum_bytes() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("A"),
+            Token::UnitVariant {
+                name: "Data",
+                variant: "A",
+            },
             Token::Str("c"),
             Token::Struct { name: "A", len: 1 },
             Token::Str("a"),
@@ -2385,7 +2129,10 @@ fn test_adjacently_tagged_enum_bytes() {
                 len: 2,
             },
             Token::Bytes(b"t"),
-            Token::Str("A"),
+            Token::UnitVariant {
+                name: "Data",
+                variant: "A",
+            },
             Token::Bytes(b"c"),
             Token::Struct { name: "A", len: 1 },
             Token::Str("a"),
@@ -2426,7 +2173,10 @@ fn test_adjacently_tagged_enum_containing_flatten() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("A"),
+            Token::UnitVariant {
+                name: "Data",
+                variant: "A",
+            },
             Token::Str("c"),
             Token::Map { len: None },
             Token::Str("a"),
@@ -2630,35 +2380,6 @@ fn test_partially_untagged_enum_desugared() {
     );
 }
 
-#[test]
-fn test_flatten_untagged_enum() {
-    #[derive(Serialize, Deserialize, PartialEq, Debug)]
-    struct Outer {
-        #[serde(flatten)]
-        inner: Inner,
-    }
-
-    #[derive(Serialize, Deserialize, PartialEq, Debug)]
-    #[serde(untagged)]
-    enum Inner {
-        Variant { a: i32 },
-    }
-
-    let data = Outer {
-        inner: Inner::Variant { a: 0 },
-    };
-
-    assert_tokens(
-        &data,
-        &[
-            Token::Map { len: None },
-            Token::Str("a"),
-            Token::I32(0),
-            Token::MapEnd,
-        ],
-    );
-}
-
 #[test]
 fn test_flatten_option() {
     #[derive(Serialize, Deserialize, PartialEq, Debug)]
@@ -2815,48 +2536,6 @@ fn test_internally_tagged_unit_enum_with_unknown_fields() {
     );
 }
 
-#[test]
-fn test_flattened_internally_tagged_unit_enum_with_unknown_fields() {
-    #[derive(Deserialize, PartialEq, Debug)]
-    struct S {
-        #[serde(flatten)]
-        x: X,
-        #[serde(flatten)]
-        y: Y,
-    }
-
-    #[derive(Deserialize, PartialEq, Debug)]
-    #[serde(tag = "typeX")]
-    enum X {
-        A,
-    }
-
-    #[derive(Deserialize, PartialEq, Debug)]
-    #[serde(tag = "typeY")]
-    enum Y {
-        B { c: u32 },
-    }
-
-    let s = S {
-        x: X::A,
-        y: Y::B { c: 0 },
-    };
-
-    assert_de_tokens(
-        &s,
-        &[
-            Token::Map { len: None },
-            Token::Str("typeX"),
-            Token::Str("A"),
-            Token::Str("typeY"),
-            Token::Str("B"),
-            Token::Str("c"),
-            Token::I32(0),
-            Token::MapEnd,
-        ],
-    );
-}
-
 #[test]
 fn test_flatten_any_after_flatten_struct() {
     #[derive(PartialEq, Debug)]
@@ -3087,7 +2766,7 @@ fn test_expecting_message_adjacently_tagged_enum() {
     // 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"#,
+        r#"invalid type: unit value, expected variant of enum Enum"#,
     );
 }
 
@@ -3149,3 +2828,345 @@ fn test_expecting_message_identifier_enum() {
         r#"invalid type: map, expected something strange..."#,
     );
 }
+
+mod flatten {
+    use super::*;
+
+    mod enum_ {
+        use super::*;
+
+        mod externally_tagged {
+            use super::*;
+            use std::iter::FromIterator;
+
+            #[derive(Debug, PartialEq, Serialize, Deserialize)]
+            struct Flatten {
+                #[serde(flatten)]
+                data: Enum,
+
+                #[serde(flatten)]
+                extra: HashMap<String, String>,
+            }
+
+            #[derive(Debug, PartialEq, Serialize, Deserialize)]
+            enum Enum {
+                Newtype(HashMap<String, String>),
+                Tuple(u32, u32),
+                Struct { index: u32, value: u32 },
+            }
+
+            #[test]
+            fn newtype() {
+                assert_tokens(
+                    &Flatten {
+                        data: Enum::Newtype(HashMap::from_iter([("key".into(), "value".into())])),
+                        extra: HashMap::from_iter([("extra_key".into(), "extra value".into())]),
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("Newtype"), // variant
+                        Token::Map { len: Some(1) },
+                        Token::Str("key"),
+                        Token::Str("value"),
+                        Token::MapEnd,
+                        Token::Str("extra_key"),
+                        Token::Str("extra value"),
+                        Token::MapEnd,
+                    ],
+                );
+            }
+
+            // Reaches crate::private::de::content::VariantDeserializer::tuple_variant
+            // Content::Seq case
+            // via FlatMapDeserializer::deserialize_enum
+            #[test]
+            fn tuple() {
+                assert_tokens(
+                    &Flatten {
+                        data: Enum::Tuple(0, 42),
+                        extra: HashMap::from_iter([("extra_key".into(), "extra value".into())]),
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("Tuple"), // variant
+                        Token::Seq { len: Some(2) },
+                        Token::U32(0),
+                        Token::U32(42),
+                        Token::SeqEnd,
+                        Token::Str("extra_key"),
+                        Token::Str("extra value"),
+                        Token::MapEnd,
+                    ],
+                );
+            }
+
+            // Reaches crate::private::de::content::VariantDeserializer::struct_variant
+            // Content::Seq case
+            // via FlatMapDeserializer::deserialize_enum
+            #[test]
+            fn struct_from_seq() {
+                assert_de_tokens(
+                    &Flatten {
+                        data: Enum::Struct {
+                            index: 0,
+                            value: 42,
+                        },
+                        extra: HashMap::from_iter([("extra_key".into(), "extra value".into())]),
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("Struct"), // variant
+                        Token::Seq { len: Some(2) },
+                        Token::U32(0),  // index
+                        Token::U32(42), // value
+                        Token::SeqEnd,
+                        Token::Str("extra_key"),
+                        Token::Str("extra value"),
+                        Token::MapEnd,
+                    ],
+                );
+            }
+
+            // Reaches crate::private::de::content::VariantDeserializer::struct_variant
+            // Content::Map case
+            // via FlatMapDeserializer::deserialize_enum
+            #[test]
+            fn struct_from_map() {
+                assert_tokens(
+                    &Flatten {
+                        data: Enum::Struct {
+                            index: 0,
+                            value: 42,
+                        },
+                        extra: HashMap::from_iter([("extra_key".into(), "extra value".into())]),
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("Struct"), // variant
+                        Token::Struct {
+                            len: 2,
+                            name: "Struct",
+                        },
+                        Token::Str("index"),
+                        Token::U32(0),
+                        Token::Str("value"),
+                        Token::U32(42),
+                        Token::StructEnd,
+                        Token::Str("extra_key"),
+                        Token::Str("extra value"),
+                        Token::MapEnd,
+                    ],
+                );
+            }
+        }
+
+        mod adjacently_tagged {
+            use super::*;
+
+            #[derive(Debug, PartialEq, Serialize, Deserialize)]
+            struct Flatten {
+                outer: u32,
+
+                #[serde(flatten)]
+                data: NewtypeWrapper,
+            }
+
+            #[derive(Debug, PartialEq, Serialize, Deserialize)]
+            struct NewtypeWrapper(pub Enum);
+
+            #[derive(Debug, PartialEq, Serialize, Deserialize)]
+            #[serde(tag = "tag", content = "content")]
+            enum Enum {
+                Newtype(NewtypeVariant),
+                Struct { index: u32, value: u32 },
+            }
+
+            #[derive(Debug, PartialEq, Serialize, Deserialize)]
+            struct NewtypeVariant {
+                value: u32,
+            }
+
+            #[test]
+            fn struct_() {
+                assert_tokens(
+                    &Flatten {
+                        outer: 42,
+                        data: NewtypeWrapper(Enum::Struct {
+                            index: 0,
+                            value: 42,
+                        }),
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("outer"),
+                        Token::U32(42),
+                        Token::Str("tag"),
+                        Token::UnitVariant {
+                            name: "Enum",
+                            variant: "Struct",
+                        },
+                        Token::Str("content"),
+                        Token::Struct {
+                            len: 2,
+                            name: "Struct",
+                        },
+                        Token::Str("index"),
+                        Token::U32(0),
+                        Token::Str("value"),
+                        Token::U32(42),
+                        Token::StructEnd,
+                        Token::MapEnd,
+                    ],
+                );
+            }
+
+            #[test]
+            fn newtype() {
+                assert_tokens(
+                    &Flatten {
+                        outer: 42,
+                        data: NewtypeWrapper(Enum::Newtype(NewtypeVariant { value: 23 })),
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("outer"),
+                        Token::U32(42),
+                        Token::Str("tag"),
+                        Token::UnitVariant {
+                            name: "Enum",
+                            variant: "Newtype",
+                        },
+                        Token::Str("content"),
+                        Token::Struct {
+                            len: 1,
+                            name: "NewtypeVariant",
+                        },
+                        Token::Str("value"),
+                        Token::U32(23),
+                        Token::StructEnd,
+                        Token::MapEnd,
+                    ],
+                );
+            }
+        }
+
+        mod internally_tagged {
+            use super::*;
+
+            #[test]
+            fn structs() {
+                #[derive(Debug, PartialEq, Serialize, Deserialize)]
+                struct Flatten {
+                    #[serde(flatten)]
+                    x: X,
+                    #[serde(flatten)]
+                    y: Y,
+                }
+
+                #[derive(Debug, PartialEq, Serialize, Deserialize)]
+                #[serde(tag = "typeX")]
+                enum X {
+                    A { a: i32 },
+                    B { b: i32 },
+                }
+
+                #[derive(Debug, PartialEq, Serialize, Deserialize)]
+                #[serde(tag = "typeY")]
+                enum Y {
+                    C { c: i32 },
+                    D { d: i32 },
+                }
+
+                assert_tokens(
+                    &Flatten {
+                        x: X::B { b: 1 },
+                        y: Y::D { d: 2 },
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("typeX"),
+                        Token::Str("B"),
+                        Token::Str("b"),
+                        Token::I32(1),
+                        Token::Str("typeY"),
+                        Token::Str("D"),
+                        Token::Str("d"),
+                        Token::I32(2),
+                        Token::MapEnd,
+                    ],
+                );
+            }
+
+            #[test]
+            fn unit_enum_with_unknown_fields() {
+                #[derive(Debug, PartialEq, Deserialize)]
+                struct Flatten {
+                    #[serde(flatten)]
+                    x: X,
+                    #[serde(flatten)]
+                    y: Y,
+                }
+
+                #[derive(Debug, PartialEq, Deserialize)]
+                #[serde(tag = "typeX")]
+                enum X {
+                    A,
+                }
+
+                #[derive(Debug, PartialEq, Deserialize)]
+                #[serde(tag = "typeY")]
+                enum Y {
+                    B { c: u32 },
+                }
+
+                assert_de_tokens(
+                    &Flatten {
+                        x: X::A,
+                        y: Y::B { c: 0 },
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("typeX"),
+                        Token::Str("A"),
+                        Token::Str("typeY"),
+                        Token::Str("B"),
+                        Token::Str("c"),
+                        Token::I32(0),
+                        Token::MapEnd,
+                    ],
+                );
+            }
+        }
+
+        mod untagged {
+            use super::*;
+
+            #[derive(Debug, PartialEq, Serialize, Deserialize)]
+            struct Flatten {
+                #[serde(flatten)]
+                data: Enum,
+            }
+
+            #[derive(Debug, PartialEq, Serialize, Deserialize)]
+            #[serde(untagged)]
+            enum Enum {
+                Struct { a: i32 },
+            }
+
+            #[test]
+            fn struct_() {
+                assert_tokens(
+                    &Flatten {
+                        data: Enum::Struct { a: 0 },
+                    },
+                    &[
+                        Token::Map { len: None },
+                        Token::Str("a"),
+                        Token::I32(0),
+                        Token::MapEnd,
+                    ],
+                );
+            }
+        }
+    }
+}

test_suite/tests/test_identifier.rs

@@ -3,86 +3,186 @@
 #![allow(clippy::derive_partial_eq_without_eq)]
 
 use serde_derive::Deserialize;
-use serde_test::{assert_de_tokens, Token};
+use serde_test::{assert_de_tokens, assert_de_tokens_error, Token};
+
+mod variant_identifier {
+    use super::*;
 
-#[test]
-fn test_variant_identifier() {
     #[derive(Deserialize, Debug, PartialEq)]
     #[serde(variant_identifier)]
     enum V {
         Aaa,
+        #[serde(alias = "Ccc", alias = "Ddd")]
         Bbb,
     }
 
-    assert_de_tokens(&V::Aaa, &[Token::U8(0)]);
+    #[test]
-    assert_de_tokens(&V::Aaa, &[Token::U16(0)]);
+    fn variant1() {
-    assert_de_tokens(&V::Aaa, &[Token::U32(0)]);
+        assert_de_tokens(&V::Aaa, &[Token::U8(0)]);
-    assert_de_tokens(&V::Aaa, &[Token::U64(0)]);
+        assert_de_tokens(&V::Aaa, &[Token::U16(0)]);
-    assert_de_tokens(&V::Aaa, &[Token::Str("Aaa")]);
+        assert_de_tokens(&V::Aaa, &[Token::U32(0)]);
-    assert_de_tokens(&V::Aaa, &[Token::Bytes(b"Aaa")]);
+        assert_de_tokens(&V::Aaa, &[Token::U64(0)]);
+        assert_de_tokens(&V::Aaa, &[Token::Str("Aaa")]);
+        assert_de_tokens(&V::Aaa, &[Token::Bytes(b"Aaa")]);
+    }
+
+    #[test]
+    fn aliases() {
+        assert_de_tokens(&V::Bbb, &[Token::U8(1)]);
+        assert_de_tokens(&V::Bbb, &[Token::U16(1)]);
+        assert_de_tokens(&V::Bbb, &[Token::U32(1)]);
+        assert_de_tokens(&V::Bbb, &[Token::U64(1)]);
+
+        assert_de_tokens(&V::Bbb, &[Token::Str("Bbb")]);
+        assert_de_tokens(&V::Bbb, &[Token::Bytes(b"Bbb")]);
+
+        assert_de_tokens(&V::Bbb, &[Token::Str("Ccc")]);
+        assert_de_tokens(&V::Bbb, &[Token::Bytes(b"Ccc")]);
+
+        assert_de_tokens(&V::Bbb, &[Token::Str("Ddd")]);
+        assert_de_tokens(&V::Bbb, &[Token::Bytes(b"Ddd")]);
+    }
+
+    #[test]
+    fn unknown() {
+        assert_de_tokens_error::<V>(
+            &[Token::U8(42)],
+            "invalid value: integer `42`, expected variant index 0 <= i < 2",
+        );
+        assert_de_tokens_error::<V>(
+            &[Token::U16(42)],
+            "invalid value: integer `42`, expected variant index 0 <= i < 2",
+        );
+        assert_de_tokens_error::<V>(
+            &[Token::U32(42)],
+            "invalid value: integer `42`, expected variant index 0 <= i < 2",
+        );
+        assert_de_tokens_error::<V>(
+            &[Token::U64(42)],
+            "invalid value: integer `42`, expected variant index 0 <= i < 2",
+        );
+        assert_de_tokens_error::<V>(
+            &[Token::Str("Unknown")],
+            "unknown variant `Unknown`, expected one of `Aaa`, `Bbb`, `Ccc`, `Ddd`",
+        );
+        assert_de_tokens_error::<V>(
+            &[Token::Bytes(b"Unknown")],
+            "unknown variant `Unknown`, expected one of `Aaa`, `Bbb`, `Ccc`, `Ddd`",
+        );
+    }
 }
 
-#[test]
+mod field_identifier {
-fn test_field_identifier() {
+    use super::*;
+
     #[derive(Deserialize, Debug, PartialEq)]
     #[serde(field_identifier, rename_all = "snake_case")]
     enum F {
         Aaa,
+        #[serde(alias = "ccc", alias = "ddd")]
         Bbb,
     }
 
-    assert_de_tokens(&F::Aaa, &[Token::U8(0)]);
+    #[test]
-    assert_de_tokens(&F::Aaa, &[Token::U16(0)]);
+    fn field1() {
-    assert_de_tokens(&F::Aaa, &[Token::U32(0)]);
+        assert_de_tokens(&F::Aaa, &[Token::U8(0)]);
-    assert_de_tokens(&F::Aaa, &[Token::U64(0)]);
+        assert_de_tokens(&F::Aaa, &[Token::U16(0)]);
-    assert_de_tokens(&F::Aaa, &[Token::Str("aaa")]);
+        assert_de_tokens(&F::Aaa, &[Token::U32(0)]);
-    assert_de_tokens(&F::Aaa, &[Token::Bytes(b"aaa")]);
+        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")]);
-#[test]
-fn test_unit_fallthrough() {
-    #[derive(Deserialize, Debug, PartialEq)]
-    #[serde(field_identifier, rename_all = "snake_case")]
-    enum F {
-        Aaa,
-        Bbb,
-        #[serde(other)]
-        Other,
     }
 
-    assert_de_tokens(&F::Other, &[Token::U8(42)]);
+    #[test]
-    assert_de_tokens(&F::Other, &[Token::U16(42)]);
+    fn aliases() {
-    assert_de_tokens(&F::Other, &[Token::U32(42)]);
+        assert_de_tokens(&F::Bbb, &[Token::U8(1)]);
-    assert_de_tokens(&F::Other, &[Token::U64(42)]);
+        assert_de_tokens(&F::Bbb, &[Token::U16(1)]);
-    assert_de_tokens(&F::Other, &[Token::Str("x")]);
+        assert_de_tokens(&F::Bbb, &[Token::U32(1)]);
-}
+        assert_de_tokens(&F::Bbb, &[Token::U64(1)]);
 
-#[test]
+        assert_de_tokens(&F::Bbb, &[Token::Str("bbb")]);
-fn test_newtype_fallthrough() {
+        assert_de_tokens(&F::Bbb, &[Token::Bytes(b"bbb")]);
-    #[derive(Deserialize, Debug, PartialEq)]
+
-    #[serde(field_identifier, rename_all = "snake_case")]
+        assert_de_tokens(&F::Bbb, &[Token::Str("ccc")]);
-    enum F {
+        assert_de_tokens(&F::Bbb, &[Token::Bytes(b"ccc")]);
-        Aaa,
+
-        Bbb,
+        assert_de_tokens(&F::Bbb, &[Token::Str("ddd")]);
-        Other(String),
+        assert_de_tokens(&F::Bbb, &[Token::Bytes(b"ddd")]);
     }
 
-    assert_de_tokens(&F::Other("x".to_owned()), &[Token::Str("x")]);
+    #[test]
-}
+    fn unknown() {
-
+        assert_de_tokens_error::<F>(
-#[test]
+            &[Token::U8(42)],
-fn test_newtype_fallthrough_generic() {
+            "invalid value: integer `42`, expected field index 0 <= i < 2",
-    #[derive(Deserialize, Debug, PartialEq)]
+        );
-    #[serde(field_identifier, rename_all = "snake_case")]
+        assert_de_tokens_error::<F>(
-    enum F<T> {
+            &[Token::U16(42)],
-        Aaa,
+            "invalid value: integer `42`, expected field index 0 <= i < 2",
-        Bbb,
+        );
-        Other(T),
+        assert_de_tokens_error::<F>(
+            &[Token::U32(42)],
+            "invalid value: integer `42`, expected field index 0 <= i < 2",
+        );
+        assert_de_tokens_error::<F>(
+            &[Token::U64(42)],
+            "invalid value: integer `42`, expected field index 0 <= i < 2",
+        );
+        assert_de_tokens_error::<F>(
+            &[Token::Str("unknown")],
+            "unknown field `unknown`, expected one of `aaa`, `bbb`, `ccc`, `ddd`",
+        );
+        assert_de_tokens_error::<F>(
+            &[Token::Bytes(b"unknown")],
+            "unknown field `unknown`, expected one of `aaa`, `bbb`, `ccc`, `ddd`",
+        );
     }
 
-    assert_de_tokens(&F::Other(42u8), &[Token::U8(42)]);
+    #[test]
-    assert_de_tokens(&F::Other(42u16), &[Token::U16(42)]);
+    fn unit_fallthrough() {
-    assert_de_tokens(&F::Other(42u32), &[Token::U32(42)]);
+        #[derive(Deserialize, Debug, PartialEq)]
-    assert_de_tokens(&F::Other(42u64), &[Token::U64(42)]);
+        #[serde(field_identifier, rename_all = "snake_case")]
-    assert_de_tokens(&F::Other("x".to_owned()), &[Token::Str("x")]);
+        enum F {
+            Aaa,
+            Bbb,
+            #[serde(other)]
+            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")]);
+    }
+
+    #[test]
+    fn newtype_fallthrough() {
+        #[derive(Deserialize, Debug, PartialEq)]
+        #[serde(field_identifier, rename_all = "snake_case")]
+        enum F {
+            Aaa,
+            Bbb,
+            Other(String),
+        }
+
+        assert_de_tokens(&F::Other("x".to_owned()), &[Token::Str("x")]);
+    }
+
+    #[test]
+    fn newtype_fallthrough_generic() {
+        #[derive(Deserialize, Debug, PartialEq)]
+        #[serde(field_identifier, rename_all = "snake_case")]
+        enum F<T> {
+            Aaa,
+            Bbb,
+            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/test_macros.rs

@@ -472,7 +472,10 @@ fn test_adjacently_tagged_newtype_struct() {
             },
             Token::U32(5),
             Token::Str("t"),
-            Token::Str("Newtype"),
+            Token::UnitVariant {
+                name: "E",
+                variant: "Newtype",
+            },
             Token::StructEnd,
         ],
     );
@@ -1066,7 +1069,10 @@ fn test_adjacently_tagged_enum() {
                 len: 1,
             },
             Token::Str("t"),
-            Token::Str("Unit"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Unit",
+            },
             Token::StructEnd,
         ],
     );
@@ -1080,7 +1086,10 @@ fn test_adjacently_tagged_enum() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("Unit"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Unit",
+            },
             Token::StructEnd,
         ],
     );
@@ -1094,7 +1103,10 @@ fn test_adjacently_tagged_enum() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("Unit"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Unit",
+            },
             Token::Str("c"),
             Token::Unit,
             Token::StructEnd,
@@ -1112,7 +1124,10 @@ fn test_adjacently_tagged_enum() {
             Token::Str("c"),
             Token::Unit,
             Token::Str("t"),
-            Token::Str("Unit"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Unit",
+            },
             Token::StructEnd,
         ],
     );
@@ -1128,7 +1143,10 @@ fn test_adjacently_tagged_enum() {
             Token::Str("f"),
             Token::Unit,
             Token::Str("t"),
-            Token::Str("Unit"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Unit",
+            },
             Token::Str("g"),
             Token::Unit,
             Token::Str("c"),
@@ -1148,7 +1166,10 @@ fn test_adjacently_tagged_enum() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("Newtype"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Newtype",
+            },
             Token::Str("c"),
             Token::U8(1),
             Token::StructEnd,
@@ -1166,7 +1187,10 @@ fn test_adjacently_tagged_enum() {
             Token::Str("c"),
             Token::U8(1),
             Token::Str("t"),
-            Token::Str("Newtype"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Newtype",
+            },
             Token::StructEnd,
         ],
     );
@@ -1180,7 +1204,10 @@ fn test_adjacently_tagged_enum() {
                 len: 1,
             },
             Token::Str("t"),
-            Token::Str("Newtype"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Newtype",
+            },
             Token::StructEnd,
         ],
     );
@@ -1194,7 +1221,10 @@ fn test_adjacently_tagged_enum() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("Tuple"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Tuple",
+            },
             Token::Str("c"),
             Token::Tuple { len: 2 },
             Token::U8(1),
@@ -1218,7 +1248,10 @@ fn test_adjacently_tagged_enum() {
             Token::U8(1),
             Token::TupleEnd,
             Token::Str("t"),
-            Token::Str("Tuple"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Tuple",
+            },
             Token::StructEnd,
         ],
     );
@@ -1232,7 +1265,10 @@ fn test_adjacently_tagged_enum() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("Struct"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Struct",
+            },
             Token::Str("c"),
             Token::Struct {
                 name: "Struct",
@@ -1262,7 +1298,10 @@ fn test_adjacently_tagged_enum() {
             Token::U8(1),
             Token::StructEnd,
             Token::Str("t"),
-            Token::Str("Struct"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Struct",
+            },
             Token::StructEnd,
         ],
     );
@@ -1278,7 +1317,10 @@ fn test_adjacently_tagged_enum() {
             Token::U64(1), // content field
             Token::U8(1),
             Token::U64(0), // tag field
-            Token::Str("Newtype"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Newtype",
+            },
             Token::StructEnd,
         ],
     );
@@ -1294,7 +1336,10 @@ fn test_adjacently_tagged_enum() {
             Token::Bytes(b"c"),
             Token::U8(1),
             Token::Bytes(b"t"),
-            Token::Str("Newtype"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Newtype",
+            },
             Token::StructEnd,
         ],
     );
@@ -1316,7 +1361,10 @@ fn test_adjacently_tagged_enum_deny_unknown_fields() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("Unit"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Unit",
+            },
             Token::Str("c"),
             Token::Unit,
             Token::StructEnd,
@@ -1330,7 +1378,10 @@ fn test_adjacently_tagged_enum_deny_unknown_fields() {
                 len: 2,
             },
             Token::Str("t"),
-            Token::Str("Unit"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Unit",
+            },
             Token::Str("c"),
             Token::Unit,
             Token::Str("h"),
@@ -1369,7 +1420,10 @@ fn test_adjacently_tagged_enum_deny_unknown_fields() {
                 len: 2,
             },
             Token::U64(0), // tag field
-            Token::Str("Unit"),
+            Token::UnitVariant {
+                name: "AdjacentlyTagged",
+                variant: "Unit",
+            },
             Token::U64(3),
         ],
         r#"invalid value: integer `3`, expected "t" or "c""#,
@@ -1429,6 +1483,9 @@ fn test_enum_in_internally_tagged_enum() {
         ],
     );
 
+    // Reaches crate::private::de::content::VariantDeserializer::tuple_variant
+    // Content::Seq case
+    // via ContentDeserializer::deserialize_enum
     assert_tokens(
         &Outer::Inner(Inner::Tuple(1, 1)),
         &[
@@ -1447,6 +1504,9 @@ fn test_enum_in_internally_tagged_enum() {
         ],
     );
 
+    // Reaches crate::private::de::content::VariantDeserializer::struct_variant
+    // Content::Map case
+    // via ContentDeserializer::deserialize_enum
     assert_tokens(
         &Outer::Inner(Inner::Struct { f: 1 }),
         &[
@@ -1464,6 +1524,23 @@ fn test_enum_in_internally_tagged_enum() {
             Token::MapEnd,
         ],
     );
+
+    // Reaches crate::private::de::content::VariantDeserializer::struct_variant
+    // Content::Seq case
+    // via ContentDeserializer::deserialize_enum
+    assert_de_tokens(
+        &Outer::Inner(Inner::Struct { f: 1 }),
+        &[
+            Token::Map { len: Some(2) },
+            Token::Str("type"),
+            Token::Str("Inner"),
+            Token::Str("Struct"),
+            Token::Seq { len: Some(1) },
+            Token::U8(1), // f
+            Token::SeqEnd,
+            Token::MapEnd,
+        ],
+    );
 }
 
 #[test]
@@ -1542,7 +1619,10 @@ fn test_internally_tagged_struct_with_flattened_field() {
             Token::Str("tag_struct"),
             Token::Str("Struct"),
             Token::Str("tag_enum"),
-            Token::Str("A"),
+            Token::UnitVariant {
+                name: "Enum",
+                variant: "A",
+            },
             Token::Str("content"),
             Token::U64(0),
             Token::MapEnd,

test_suite/tests/ui/default-attribute/enum.stderr

@@ -1,4 +1,4 @@
-error: #[serde(default)] can only be used on structs with named fields
+error: #[serde(default)] can only be used on structs
  --> tests/ui/default-attribute/enum.rs:4:9
   |
 4 | #[serde(default)]

test_suite/tests/ui/default-attribute/enum_path.stderr

@@ -1,4 +1,4 @@
-error: #[serde(default = "...")] can only be used on structs with named fields
+error: #[serde(default = "...")] can only be used on structs
  --> tests/ui/default-attribute/enum_path.rs:4:9
   |
 4 | #[serde(default = "default_e")]

test_suite/tests/ui/default-attribute/nameless_struct_fields.rs

@@ -1,7 +0,0 @@
-use serde_derive::Deserialize;
-
-#[derive(Deserialize)]
-#[serde(default)]
-struct T(u8, u8);
-
-fn main() {}

test_suite/tests/ui/default-attribute/nameless_struct_fields.stderr

@@ -1,5 +0,0 @@
-error: #[serde(default)] can only be used on structs with named fields
- --> tests/ui/default-attribute/nameless_struct_fields.rs:5:9
-  |
-5 | struct T(u8, u8);
-  |         ^^^^^^^^

test_suite/tests/ui/default-attribute/nameless_struct_fields_path.rs

@@ -1,7 +0,0 @@
-use serde_derive::Deserialize;
-
-#[derive(Deserialize)]
-#[serde(default = "default_t")]
-struct T(u8, u8);
-
-fn main() {}

test_suite/tests/ui/default-attribute/nameless_struct_fields_path.stderr

@@ -1,5 +0,0 @@
-error: #[serde(default = "...")] can only be used on structs with named fields
- --> tests/ui/default-attribute/nameless_struct_fields_path.rs:4:9
-  |
-4 | #[serde(default = "default_t")]
-  |         ^^^^^^^^^^^^^^^^^^^^^

test_suite/tests/ui/default-attribute/tuple_struct.rs

@@ -0,0 +1,47 @@
+use serde_derive::Deserialize;
+
+// No errors expected.
+#[derive(Deserialize)]
+struct T0(u8, u8);
+
+// No errors expected:
+// - If both fields are provided, both get value from data.
+// - If only one field is provided, the second gets default value.
+#[derive(Deserialize)]
+struct T1(u8, #[serde(default)] u8);
+
+// ERROR: The first field can get default value only if sequence is empty, but
+// that mean that all other fields cannot be deserialized without errors.
+#[derive(Deserialize)]
+struct T2(#[serde(default)] u8, u8, u8);
+
+// No errors expected:
+// - If both fields are provided, both get value from data.
+// - If only one field is provided, the second gets default value.
+// - If no fields are provided, both get default value.
+#[derive(Deserialize)]
+struct T3(#[serde(default)] u8, #[serde(default)] u8);
+
+////////////////////////////////////////////////////////////////////////////////
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize, Default)]
+#[serde(default)]
+struct T4(u8, u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize, Default)]
+#[serde(default)]
+struct T5(#[serde(default)] u8, u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize, Default)]
+#[serde(default)]
+struct T6(u8, #[serde(default)] u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize, Default)]
+#[serde(default)]
+struct T7(#[serde(default)] u8, #[serde(default)] u8);
+
+fn main() {}

test_suite/tests/ui/default-attribute/tuple_struct.stderr

@@ -0,0 +1,11 @@
+error: field must have #[serde(default)] because previous field 0 has #[serde(default)]
+  --> tests/ui/default-attribute/tuple_struct.rs:16:33
+   |
+16 | struct T2(#[serde(default)] u8, u8, u8);
+   |                                 ^^
+
+error: field must have #[serde(default)] because previous field 0 has #[serde(default)]
+  --> tests/ui/default-attribute/tuple_struct.rs:16:37
+   |
+16 | struct T2(#[serde(default)] u8, u8, u8);
+   |                                     ^^

test_suite/tests/ui/default-attribute/tuple_struct_path.rs

@@ -0,0 +1,76 @@
+use serde_derive::Deserialize;
+
+fn d<T>() -> T {
+    unimplemented!()
+}
+
+// No errors expected:
+// - If both fields are provided, both get value from data.
+// - If only one field is provided, the second gets default value.
+#[derive(Deserialize)]
+struct T1(u8, #[serde(default = "d")] u8);
+
+// ERROR: The first field can get default value only if sequence is empty, but
+// that mean that all other fields cannot be deserialized without errors.
+#[derive(Deserialize)]
+struct T2(#[serde(default = "d")] u8, u8, u8);
+
+// No errors expected:
+// - If both fields are provided, both get value from data.
+// - If only one field is provided, the second gets default value.
+// - If no fields are provided, both get default value.
+#[derive(Deserialize)]
+struct T3(#[serde(default = "d")] u8, #[serde(default = "d")] u8);
+
+////////////////////////////////////////////////////////////////////////////////
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize, Default)]
+#[serde(default)]
+struct T1D(#[serde(default = "d")] u8, u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize, Default)]
+#[serde(default)]
+struct T2D(u8, #[serde(default = "d")] u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize, Default)]
+#[serde(default)]
+struct T3D(#[serde(default = "d")] u8, #[serde(default = "d")] u8);
+
+////////////////////////////////////////////////////////////////////////////////
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize)]
+#[serde(default = "d")]
+struct T1Path(#[serde(default)] u8, u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize)]
+#[serde(default = "d")]
+struct T2Path(u8, #[serde(default)] u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize)]
+#[serde(default = "d")]
+struct T3Path(#[serde(default)] u8, #[serde(default)] u8);
+
+////////////////////////////////////////////////////////////////////////////////
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize)]
+#[serde(default = "d")]
+struct T1PathD(#[serde(default = "d")] u8, u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize)]
+#[serde(default = "d")]
+struct T2PathD(u8, #[serde(default = "d")] u8);
+
+// No errors expected -- missing fields get default values.
+#[derive(Deserialize)]
+#[serde(default = "d")]
+struct T3PathD(#[serde(default = "d")] u8, #[serde(default = "d")] u8);
+
+fn main() {}

test_suite/tests/ui/default-attribute/tuple_struct_path.stderr

@@ -0,0 +1,11 @@
+error: field must have #[serde(default)] because previous field 0 has #[serde(default)]
+  --> tests/ui/default-attribute/tuple_struct_path.rs:16:39
+   |
+16 | struct T2(#[serde(default = "d")] u8, u8, u8);
+   |                                       ^^
+
+error: field must have #[serde(default)] because previous field 0 has #[serde(default)]
+  --> tests/ui/default-attribute/tuple_struct_path.rs:16:43
+   |
+16 | struct T2(#[serde(default = "d")] u8, u8, u8);
+   |                                           ^^