Release 1.0.109

* Deserialize adjacently tagged newtype variants with optional content as None instead of erroring when content field is missing

* refactor to remove duplicate code and remove panic

.github/workflows/ci.yml

@@ -0,0 +1,155 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+  schedule: [cron: "40 1 * * *"]
+
+jobs:
+  test:
+    name: Test suite
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: cd test_suite && cargo test --features unstable
+
+  windows:
+    name: Test suite (windows)
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: cd test_suite && cargo test --features unstable -- --skip ui --exact
+
+  stable:
+    name: Rust stable
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cd serde && cargo build --features rc
+      - run: cd serde && cargo build --no-default-features
+      - run: cd serde_test && cargo build
+      - run: cd serde_test && cargo test --features serde/derive,serde/rc
+
+  beta:
+    name: Rust beta
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@beta
+      - run: cd serde && cargo build --features rc
+      - run: cd test_suite && cargo test
+
+  nightly:
+    name: Rust nightly ${{matrix.os == 'windows' && '(windows)' || ''}}
+    runs-on: ${{matrix.os}}-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu, windows]
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: cd serde && cargo build
+      - run: cd serde && cargo build --no-default-features
+      - run: cd serde && cargo build --no-default-features --features alloc
+      - run: cd serde && cargo build --no-default-features --features rc,alloc
+      - run: cd serde && cargo test --features derive,rc,unstable
+      - run: cd test_suite/no_std && cargo build
+        if: matrix.os != 'windows'
+
+  msrv:
+    name: Rust 1.13.0
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@1.13.0
+      - name: Get timestamp for cache
+        id: date
+        run: echo ::set-output name=yearmo::$(date +%Y%m)
+      - uses: actions/cache@v1
+        with:
+          path: ~/.cargo/registry/index
+          key: cargo-registry-index-${{steps.date.outputs.yearmo}}
+      - run: cd serde && cargo build --features rc
+      - run: cd serde && cargo build --no-default-features
+      - run: cd serde_test && cargo build
+
+  build:
+    name: Rust ${{matrix.rust}}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        rust: [1.19.0, 1.20.0, 1.21.0, 1.25.0, 1.26.0, 1.34.0]
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{matrix.rust}}
+      - 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]
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{matrix.rust}}
+        # Work around failing to parse manifest because editions are unstable.
+      - run: sed -i /test_suite/d Cargo.toml
+      - run: cd serde && cargo build --no-default-features
+      - run: cd serde && cargo build
+
+  alloc:
+    name: Rust 1.36.0
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@1.36.0
+      - run: cd serde && cargo build --no-default-features --features alloc
+
+  emscripten:
+    name: Emscripten
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@nightly
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 9
+      - name: Install cargo-web
+        run: |
+          CARGO_WEB_RELEASE=$(curl -L -s -H Accept:application/json https://github.com/koute/cargo-web/releases/latest)
+          CARGO_WEB_VERSION=$(echo "${CARGO_WEB_RELEASE}" | jq -r .tag_name)
+          CARGO_WEB_URL="https://github.com/koute/cargo-web/releases/download/${CARGO_WEB_VERSION}/cargo-web-x86_64-unknown-linux-gnu.gz"
+          mkdir -p ~/.cargo/bin
+          curl -L "${CARGO_WEB_URL}" | gzip -d > ~/.cargo/bin/cargo-web
+          chmod +x ~/.cargo/bin/cargo-web
+      - run: cd test_suite && cargo web test --target=asmjs-unknown-emscripten --nodejs
+        continue-on-error: true
+      - run: cd test_suite && cargo web test --target=wasm32-unknown-emscripten --nodejs
+        continue-on-error: true
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    if: github.event_name != 'pull_request'
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@clippy
+        # The need for -Aredundant_field_names here is a Clippy bug.
+        # https://github.com/rust-lang/rust-clippy/issues/5356
+      - run: cd serde && cargo clippy --features rc,unstable -- -D clippy::all -A clippy::redundant_field_names
+      - run: cd serde_derive && cargo clippy -- -D clippy::all
+      - run: cd serde_test && cargo clippy -- -D clippy::all -A clippy::redundant_field_names
+      - run: cd test_suite && cargo clippy --tests --features unstable -- -D clippy::all -A clippy::redundant_field_names
+      - run: cd test_suite/no_std && cargo clippy -- -D clippy::all -A clippy::redundant_field_names

.travis.yml

@@ -1,107 +0,0 @@
-language: rust
-
-matrix:
-  include:
-    - rust: stable
-      script:
-        - cd "${TRAVIS_BUILD_DIR}/serde"
-        - cargo build --features rc
-        - cargo build --no-default-features
-        - cd "${TRAVIS_BUILD_DIR}/serde_test"
-        - cargo build
-        - cargo test --features serde/derive,serde/rc
-
-    - rust: beta
-      script:
-        - cd "${TRAVIS_BUILD_DIR}/serde"
-        - cargo build --features rc
-        - cd "${TRAVIS_BUILD_DIR}/test_suite"
-        - cargo test
-
-    - rust: nightly
-      script:
-        - cd "${TRAVIS_BUILD_DIR}/serde"
-        - cargo build
-        - cargo build --no-default-features
-        - cargo build --no-default-features --features alloc
-        - cargo build --no-default-features --features rc,alloc
-        - cargo test --features derive,rc,unstable
-        - cd "${TRAVIS_BUILD_DIR}/test_suite"
-        - cargo test --features unstable
-        - cd "${TRAVIS_BUILD_DIR}/test_suite/no_std"
-        - cargo build
-
-    - rust: 1.13.0
-      script:
-        - cd "${TRAVIS_BUILD_DIR}/serde"
-        - cargo build --features rc
-        - cargo build --no-default-features
-        - cd "${TRAVIS_BUILD_DIR}/serde_test"
-        - cargo build
-
-    - rust: 1.19.0
-    - rust: 1.20.0
-    - rust: 1.21.0
-    - rust: 1.25.0
-    - rust: 1.26.0
-
-    # Work around failing to parse manifest because editions are unstable.
-    - rust: 1.27.0
-      before_script: sed -i /test_suite/d Cargo.toml
-    - rust: 1.28.0
-      before_script: sed -i /test_suite/d Cargo.toml
-
-    - rust: 1.31.0
-      script:
-        - cd "${TRAVIS_BUILD_DIR}/serde_derive"
-        - cargo build
-
-    - rust: 1.34.0
-
-    - rust: 1.36.0
-      script:
-        - cd "${TRAVIS_BUILD_DIR}/serde"
-        - cargo build --no-default-features --features alloc
-
-    - rust: nightly
-      name: Clippy
-      script:
-        - rustup component add clippy || travis_terminate 0
-        - cargo clippy -- -D clippy::all
-        - cd "${TRAVIS_BUILD_DIR}/serde"
-        - cargo clippy --features rc,unstable -- -D clippy::all
-        - cd "${TRAVIS_BUILD_DIR}/serde_derive"
-        - cargo clippy -- -D clippy::all
-        - cd "${TRAVIS_BUILD_DIR}/serde_test"
-        - cargo clippy -- -D clippy::all
-        - cd "${TRAVIS_BUILD_DIR}/test_suite"
-        - cargo clippy --tests --features unstable -- -D clippy::all
-        - cd "${TRAVIS_BUILD_DIR}/test_suite/no_std"
-        - cargo clippy -- -D clippy::all
-
-    - rust: nightly
-      name: Emscripten
-      script:
-        - CARGO_WEB_RELEASE=$(curl -L -s -H Accept:application/json https://github.com/koute/cargo-web/releases/latest)
-        - CARGO_WEB_VERSION=$(echo "${CARGO_WEB_RELEASE}" | jq -r .tag_name)
-        - CARGO_WEB_URL="https://github.com/koute/cargo-web/releases/download/${CARGO_WEB_VERSION}/cargo-web-x86_64-unknown-linux-gnu.gz"
-
-        - nvm install 9
-        - mkdir -p ~/.cargo/bin
-        - curl -L "${CARGO_WEB_URL}" | gzip -d > ~/.cargo/bin/cargo-web
-        - chmod +x ~/.cargo/bin/cargo-web
-
-        - cd "${TRAVIS_BUILD_DIR}/test_suite"
-        - cargo web test --target=asmjs-unknown-emscripten --nodejs
-        - cargo web test --target=wasm32-unknown-emscripten --nodejs
-
-  allow_failures:
-    - rust: nightly
-      name: Clippy
-    - rust: nightly
-      name: Emscripten
-
-script:
-  - cd "${TRAVIS_BUILD_DIR}/serde"
-  - cargo build --no-default-features
-  - cargo build

README.md

@@ -1,7 +1,7 @@
-# Serde   [![Build Status]][travis] [![Latest Version]][crates.io] [![serde: rustc 1.13+]][Rust 1.13] [![serde_derive: rustc 1.31+]][Rust 1.31]
+# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.13+]][Rust 1.13] [![serde_derive: rustc 1.31+]][Rust 1.31]
 
-[Build Status]: https://api.travis-ci.org/serde-rs/serde.svg?branch=master
-[travis]: https://travis-ci.org/serde-rs/serde
+[Build Status]: https://img.shields.io/github/workflow/status/serde-rs/serde/CI/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 1.13+]: https://img.shields.io/badge/serde-rustc_1.13+-lightgray.svg

appveyor.yml

@@ -1,39 +0,0 @@
-environment:
-  matrix:
-    - APPVEYOR_RUST_CHANNEL: stable
-    - APPVEYOR_RUST_CHANNEL: nightly
-
-install:
-  # Install rust, x86_64-pc-windows-msvc host
-  - curl -sSf -o rustup-init.exe https://win.rustup.rs/
-  - rustup-init.exe -y --default-host x86_64-pc-windows-msvc --default-toolchain %APPVEYOR_RUST_CHANNEL%
-  - set PATH=C:\msys64\usr\bin;%PATH%;C:\Users\appveyor\.cargo\bin
-  - rustc -vV
-  - cargo -vV
-
-build: false
-
-for:
-  - matrix:
-      only:
-        - APPVEYOR_RUST_CHANNEL: stable
-    test_script:
-      - cd %APPVEYOR_BUILD_FOLDER%\serde
-      - cargo build --features rc
-      - cargo build --no-default-features
-      - cd %APPVEYOR_BUILD_FOLDER%\serde_test
-      - cargo build
-      - cargo test --features serde/derive,serde/rc
-
-  - matrix:
-      only:
-        - APPVEYOR_RUST_CHANNEL: nightly
-    test_script:
-      - cd %APPVEYOR_BUILD_FOLDER%\serde
-      - cargo build
-      - cargo build --no-default-features
-      - cargo build --no-default-features --features alloc
-      - cargo build --no-default-features --features rc,alloc
-      - cargo test --features derive,rc,unstable
-      - cd %APPVEYOR_BUILD_FOLDER%\test_suite
-      - cargo test --features unstable

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.103" # remember to update html_root_url and serde_derive dependency
+version = "1.0.109" # remember to update html_root_url and serde_derive dependency
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -13,12 +13,8 @@ readme = "crates-io.md"
 include = ["Cargo.toml", "build.rs", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
 build = "build.rs"
 
-[badges]
-travis-ci = { repository = "serde-rs/serde" }
-appveyor = { repository = "serde-rs/serde" }
-
 [dependencies]
-serde_derive = { version = "=1.0.103", optional = true, path = "../serde_derive" }
+serde_derive = { version = "=1.0.109", optional = true, path = "../serde_derive" }
 
 [dev-dependencies]
 serde_derive = { version = "1.0", path = "../serde_derive" }
@@ -26,6 +22,9 @@ serde_derive = { version = "1.0", path = "../serde_derive" }
 [package.metadata.playground]
 features = ["derive", "rc"]
 
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
 
 ### FEATURES #################################################################
 

serde/src/de/impls.rs

@@ -90,10 +90,13 @@ macro_rules! visit_integer_method {
         {
             match FromPrimitive::$from_method(v) {
                 Some(v) => Ok(v),
-                None => Err(Error::invalid_value(Unexpected::$group(v as $group_ty), &self)),
+                None => Err(Error::invalid_value(
+                    Unexpected::$group(v as $group_ty),
+                    &self,
+                )),
             }
         }
-    }
+    };
 }
 
 macro_rules! visit_float_method {
@@ -105,7 +108,7 @@ macro_rules! visit_float_method {
         {
             Ok(v as Self::Value)
         }
-    }
+    };
 }
 
 macro_rules! impl_deserialize_num {

serde/src/lib.rs

@@ -75,14 +75,14 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.103")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.109")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Unstable functionality only if the user asks for it. For tracking and
 // discussion of these features please refer to this issue:
 //
 //    https://github.com/serde-rs/serde/issues/812
-#![cfg_attr(feature = "unstable", feature(specialization))]
+#![cfg_attr(feature = "unstable", feature(specialization, never_type))]
 #![allow(unknown_lints, bare_trait_objects, deprecated)]
 #![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
@@ -106,19 +106,25 @@
         type_complexity,
         use_self,
         zero_prefixed_literal,
+        // correctly used
+        enum_glob_use,
+        wildcard_imports,
         // not practical
         needless_pass_by_value,
         similar_names,
         too_many_lines,
         // preference
         doc_markdown,
+        unseparated_literal_suffix,
         // false positive
         needless_doctest_main,
         // noisy
+        missing_errors_doc,
         must_use_candidate,
     )
 )]
 // Rustc lints.
+#![forbid(unsafe_code)]
 #![deny(missing_docs, unused_imports)]
 
 ////////////////////////////////////////////////////////////////////////////////

serde/src/private/de.rs

@@ -53,9 +53,10 @@ where
 }
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-pub fn borrow_cow_str<'de: 'a, 'a, D>(deserializer: D) -> Result<Cow<'a, str>, D::Error>
+pub fn borrow_cow_str<'de: 'a, 'a, D, R>(deserializer: D) -> Result<R, D::Error>
 where
     D: Deserializer<'de>,
+    R: From<Cow<'a, str>>,
 {
     struct CowStrVisitor;
 
@@ -121,13 +122,14 @@ where
         }
     }
 
-    deserializer.deserialize_str(CowStrVisitor)
+    deserializer.deserialize_str(CowStrVisitor).map(From::from)
 }
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-pub fn borrow_cow_bytes<'de: 'a, 'a, D>(deserializer: D) -> Result<Cow<'a, [u8]>, D::Error>
+pub fn borrow_cow_bytes<'de: 'a, 'a, D, R>(deserializer: D) -> Result<R, D::Error>
 where
     D: Deserializer<'de>,
+    R: From<Cow<'a, [u8]>>,
 {
     struct CowBytesVisitor;
 
@@ -181,7 +183,9 @@ where
         }
     }
 
-    deserializer.deserialize_bytes(CowBytesVisitor)
+    deserializer
+        .deserialize_bytes(CowBytesVisitor)
+        .map(From::from)
 }
 
 pub mod size_hint {
@@ -2470,7 +2474,7 @@ mod content {
         where
             M: MapAccess<'de>,
         {
-            while let Some(_) = try!(access.next_entry::<IgnoredAny, IgnoredAny>()) {}
+            while try!(access.next_entry::<IgnoredAny, IgnoredAny>()).is_some() {}
             Ok(())
         }
     }

serde/src/ser/fmt.rs

@@ -0,0 +1,174 @@
+use lib::*;
+use ser::{Error, Impossible, Serialize, Serializer};
+
+impl Error for fmt::Error {
+    fn custom<T: Display>(_msg: T) -> Self {
+        fmt::Error
+    }
+}
+
+macro_rules! fmt_primitives {
+    ($($f:ident: $t:ty,)*) => {
+        $(
+            fn $f(self, v: $t) -> fmt::Result {
+                Display::fmt(&v, self)
+            }
+        )*
+    };
+}
+
+/// ```edition2018
+/// use serde::Serialize;
+/// use std::fmt::{self, Display};
+///
+/// #[derive(Serialize)]
+/// #[serde(rename_all = "kebab-case")]
+/// pub enum MessageType {
+///     StartRequest,
+///     EndRequest,
+/// }
+///
+/// impl Display for MessageType {
+///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+///         self.serialize(f)
+///     }
+/// }
+/// ```
+impl<'a, 'b> Serializer for &'a mut fmt::Formatter<'b> {
+    type Ok = ();
+    type Error = fmt::Error;
+    type SerializeSeq = Impossible<(), fmt::Error>;
+    type SerializeTuple = Impossible<(), fmt::Error>;
+    type SerializeTupleStruct = Impossible<(), fmt::Error>;
+    type SerializeTupleVariant = Impossible<(), fmt::Error>;
+    type SerializeMap = Impossible<(), fmt::Error>;
+    type SerializeStruct = Impossible<(), fmt::Error>;
+    type SerializeStructVariant = Impossible<(), fmt::Error>;
+
+    fmt_primitives! {
+        serialize_bool: bool,
+        serialize_i8: i8,
+        serialize_i16: i16,
+        serialize_i32: i32,
+        serialize_i64: i64,
+        serialize_u8: u8,
+        serialize_u16: u16,
+        serialize_u32: u32,
+        serialize_u64: u64,
+        serialize_f32: f32,
+        serialize_f64: f64,
+        serialize_char: char,
+        serialize_str: &str,
+        serialize_unit_struct: &'static str,
+    }
+
+    serde_if_integer128! {
+        fmt_primitives! {
+            serialize_i128: i128,
+            serialize_u128: u128,
+        }
+    }
+
+    fn serialize_unit_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        variant: &'static str,
+    ) -> fmt::Result {
+        Display::fmt(variant, self)
+    }
+
+    fn serialize_newtype_struct<T: ?Sized>(self, _name: &'static str, value: &T) -> fmt::Result
+    where
+        T: Serialize,
+    {
+        Serialize::serialize(value, self)
+    }
+
+    fn serialize_bytes(self, _v: &[u8]) -> fmt::Result {
+        Err(fmt::Error)
+    }
+
+    fn serialize_none(self) -> fmt::Result {
+        Err(fmt::Error)
+    }
+
+    fn serialize_some<T: ?Sized>(self, _value: &T) -> fmt::Result
+    where
+        T: Serialize,
+    {
+        Err(fmt::Error)
+    }
+
+    fn serialize_unit(self) -> fmt::Result {
+        Err(fmt::Error)
+    }
+
+    fn serialize_newtype_variant<T: ?Sized>(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _value: &T,
+    ) -> fmt::Result
+    where
+        T: Serialize,
+    {
+        Err(fmt::Error)
+    }
+
+    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq, fmt::Error> {
+        Err(fmt::Error)
+    }
+
+    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple, fmt::Error> {
+        Err(fmt::Error)
+    }
+
+    fn serialize_tuple_struct(
+        self,
+        _name: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeTupleStruct, fmt::Error> {
+        Err(fmt::Error)
+    }
+
+    fn serialize_tuple_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeTupleVariant, fmt::Error> {
+        Err(fmt::Error)
+    }
+
+    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap, fmt::Error> {
+        Err(fmt::Error)
+    }
+
+    fn serialize_struct(
+        self,
+        _name: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeStruct, fmt::Error> {
+        Err(fmt::Error)
+    }
+
+    fn serialize_struct_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize,
+    ) -> Result<Self::SerializeStructVariant, fmt::Error> {
+        Err(fmt::Error)
+    }
+
+    fn collect_str<T: ?Sized>(self, value: &T) -> fmt::Result
+    where
+        T: Display,
+    {
+        Display::fmt(value, self)
+    }
+}

serde/src/ser/impls.rs

@@ -616,7 +616,7 @@ impl Serialize for SystemTime {
         use super::SerializeStruct;
         let duration_since_epoch = self
             .duration_since(UNIX_EPOCH)
-            .expect("SystemTime must be later than UNIX_EPOCH");
+            .map_err(|_| S::Error::custom("SystemTime must be later than UNIX_EPOCH"))?;
         let mut state = try!(serializer.serialize_struct("SystemTime", 2));
         try!(state.serialize_field("secs_since_epoch", &duration_since_epoch.as_secs()));
         try!(state.serialize_field("nanos_since_epoch", &duration_since_epoch.subsec_nanos()));
@@ -633,8 +633,7 @@ impl Serialize for SystemTime {
 #[cfg(feature = "std")]
 macro_rules! serialize_display_bounded_length {
     ($value:expr, $max:expr, $serializer:expr) => {{
-        #[allow(deprecated)]
-        let mut buffer: [u8; $max] = unsafe { mem::uninitialized() };
+        let mut buffer = [0u8; $max];
         let remaining_len = {
             let mut remaining = &mut buffer[..];
             write!(remaining, "{}", $value).unwrap();
@@ -646,7 +645,7 @@ macro_rules! serialize_display_bounded_length {
         // write! only provides fmt::Formatter to Display implementations, which
         // has methods write_str and write_char but no method to write arbitrary
         // bytes. Therefore `written` must be valid UTF-8.
-        let written_str = unsafe { str::from_utf8_unchecked(written) };
+        let written_str = str::from_utf8(written).expect("must be valid UTF-8");
         $serializer.serialize_str(written_str)
     }};
 }

serde/src/ser/mod.rs

@@ -109,6 +109,7 @@
 
 use lib::*;
 
+mod fmt;
 mod impls;
 mod impossible;
 
@@ -1359,10 +1360,7 @@ pub trait Serializer: Sized {
     where
         T: Display,
     {
-        use lib::fmt::Write;
-        let mut string = String::new();
-        write!(string, "{}", value).unwrap();
-        self.serialize_str(&string)
+        self.serialize_str(&value.to_string())
     }
 
     /// Serialize a string produced by an implementation of `Display`.

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.103" # remember to update html_root_url
+version = "1.0.109" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -11,10 +11,6 @@ keywords = ["serde", "serialization", "no_std"]
 readme = "crates-io.md"
 include = ["Cargo.toml", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
 
-[badges]
-travis-ci = { repository = "serde-rs/serde" }
-appveyor = { repository = "serde-rs/serde" }
-
 [features]
 default = []
 deserialize_in_place = []
@@ -30,3 +26,6 @@ syn = { version = "1.0", features = ["visit"] }
 
 [dev-dependencies]
 serde = { version = "1.0", path = "../serde" }
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

serde_derive/src/bound.rs

@@ -156,7 +156,7 @@ pub fn with_bound(
         .collect();
 
     let mut visitor = FindTyParams {
-        all_type_params: all_type_params,
+        all_type_params,
         relevant_type_params: HashSet::new(),
         associated_type_usage: Vec::new(),
     };
@@ -271,7 +271,7 @@ pub fn with_lifetime_bound(generics: &syn::Generics, lifetime: &str) -> syn::Gen
         .collect();
 
     syn::Generics {
-        params: params,
+        params,
         ..generics.clone()
     }
 }

serde_derive/src/de.rs

@@ -134,11 +134,11 @@ impl Parameters {
         let has_getter = cont.data.has_getter();
 
         Parameters {
-            local: local,
-            this: this,
-            generics: generics,
-            borrowed: borrowed,
-            has_getter: has_getter,
+            local,
+            this,
+            generics,
+            borrowed,
+            has_getter,
         }
     }
 
@@ -310,12 +310,7 @@ fn deserialize_in_place_body(cont: &Container, params: &Parameters) -> Option<St
 
     let code = match &cont.data {
         Data::Struct(Style::Struct, fields) => {
-            if let Some(code) = deserialize_struct_in_place(None, params, fields, &cont.attrs, None)
-            {
-                code
-            } else {
-                return None;
-            }
+            deserialize_struct_in_place(None, params, fields, &cont.attrs, None)?
         }
         Data::Struct(Style::Tuple, fields) | Data::Struct(Style::Newtype, fields) => {
             deserialize_tuple_in_place(None, params, fields, &cont.attrs, None)
@@ -1158,10 +1153,13 @@ fn prepare_enum_variant_enum(
     variants: &[Variant],
     cattrs: &attr::Container,
 ) -> (TokenStream, Stmts) {
-    let variant_names_idents: Vec<_> = variants
+    let mut deserialized_variants = variants
         .iter()
         .enumerate()
-        .filter(|&(_, variant)| !variant.attrs.skip_deserializing())
+        .filter(|&(_, variant)| !variant.attrs.skip_deserializing());
+
+    let variant_names_idents: Vec<_> = deserialized_variants
+        .clone()
         .map(|(i, variant)| {
             (
                 variant.attrs.name().deserialize_name(),
@@ -1171,7 +1169,7 @@ fn prepare_enum_variant_enum(
         })
         .collect();
 
-    let other_idx = variants.iter().position(|variant| variant.attrs.other());
+    let other_idx = deserialized_variants.position(|(_, variant)| variant.attrs.other());
 
     let variants_stmt = {
         let variant_names = variant_names_idents.iter().map(|(name, _, _)| name);
@@ -1379,39 +1377,44 @@ fn deserialize_adjacently_tagged_enum(
         }
     };
 
-    fn is_unit(variant: &Variant) -> bool {
-        match variant.style {
-            Style::Unit => true,
-            Style::Struct | Style::Tuple | Style::Newtype => false,
-        }
-    }
-
     let mut missing_content = quote! {
         _serde::export::Err(<__A::Error as _serde::de::Error>::missing_field(#content))
     };
-    if variants.iter().any(is_unit) {
-        let fallthrough = if variants.iter().all(is_unit) {
-            None
-        } else {
-            Some(quote! {
-                _ => #missing_content
-            })
-        };
-        let arms = variants
-            .iter()
-            .enumerate()
-            .filter(|&(_, variant)| !variant.attrs.skip_deserializing() && is_unit(variant))
-            .map(|(i, variant)| {
-                let variant_index = field_i(i);
-                let variant_ident = &variant.ident;
-                quote! {
-                    __Field::#variant_index => _serde::export::Ok(#this::#variant_ident),
+    let mut missing_content_fallthrough = quote!();
+    let mut missing_content_arms = variants
+        .iter()
+        .enumerate()
+        .filter(|&(_, variant)| !variant.attrs.skip_deserializing())
+        .filter_map(|(i, variant)| {
+            let variant_index = field_i(i);
+            let variant_ident = &variant.ident;
+
+            let arm = match variant.style {
+                Style::Unit => quote! {
+                    _serde::export::Ok(#this::#variant_ident)
+                },
+                Style::Newtype if variant.attrs.deserialize_with().is_none() => {
+                    let span = variant.original.span();
+                    let func = quote_spanned!(span=> _serde::private::de::missing_field);
+                    quote! {
+                        #func(#content).map(#this::#variant_ident)
+                    }
                 }
-            });
+                _ => {
+                    missing_content_fallthrough = quote!(_ => #missing_content);
+                    return None;
+                }
+            };
+            Some(quote! {
+                __Field::#variant_index => #arm,
+            })
+        })
+        .peekable();
+    if missing_content_arms.peek().is_some() {
         missing_content = quote! {
             match __field {
-                #(#arms)*
-                #fallthrough
+                #(#missing_content_arms)*
+                #missing_content_fallthrough
             }
         };
     }

serde_derive/src/dummy.rs

@@ -21,14 +21,13 @@ pub fn wrap_in_const(
             use #path as _serde;
         },
         None => quote! {
-            #[allow(unknown_lints)]
-            #[cfg_attr(feature = "cargo-clippy", allow(useless_attribute))]
-            #[allow(rust_2018_idioms)]
+            #[allow(rust_2018_idioms, clippy::useless_attribute)]
             extern crate serde as _serde;
         },
     };
 
     quote! {
+        #[doc(hidden)]
         #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
         const #dummy_const: () = {
             #use_serde

serde_derive/src/internals/ast.rs

@@ -110,8 +110,8 @@ impl<'a> Container<'a> {
 
         let mut item = Container {
             ident: item.ident.clone(),
-            attrs: attrs,
-            data: data,
+            attrs,
+            data,
             generics: &item.generics,
             original: item,
         };
@@ -148,9 +148,9 @@ fn enum_from_ast<'a>(
                 struct_from_ast(cx, &variant.fields, Some(&attrs), container_default);
             Variant {
                 ident: variant.ident.clone(),
-                attrs: attrs,
-                style: style,
-                fields: fields,
+                attrs,
+                style,
+                fields,
                 original: variant,
             }
         })

serde_derive/src/internals/attr.rs

@@ -32,8 +32,8 @@ struct Attr<'c, T> {
 impl<'c, T> Attr<'c, T> {
     fn none(cx: &'c Ctxt, name: Symbol) -> Self {
         Attr {
-            cx: cx,
-            name: name,
+            cx,
+            name,
             tokens: TokenStream::new(),
             value: None,
         }
@@ -101,8 +101,8 @@ struct VecAttr<'c, T> {
 impl<'c, T> VecAttr<'c, T> {
     fn none(cx: &'c Ctxt, name: Symbol) -> Self {
         VecAttr {
-            cx: cx,
-            name: name,
+            cx,
+            name,
             first_dup_tokens: TokenStream::new(),
             values: Vec::new(),
         }
@@ -176,7 +176,7 @@ impl Name {
             serialize_renamed: ser_renamed,
             deserialize: de_name.unwrap_or(source_name),
             deserialize_renamed: de_renamed,
-            deserialize_aliases: deserialize_aliases,
+            deserialize_aliases,
         }
     }
 
@@ -716,7 +716,7 @@ fn decide_tag(
                     }
                 }
             }
-            TagType::Internal { tag: tag }
+            TagType::Internal { tag }
         }
         (Some((untagged_tokens, _)), Some((tag_tokens, _)), None) => {
             cx.error_spanned_by(
@@ -747,10 +747,7 @@ fn decide_tag(
             );
             TagType::External
         }
-        (None, Some((_, tag)), Some((_, content))) => TagType::Adjacent {
-            tag: tag,
-            content: content,
-        },
+        (None, Some((_, tag)), Some((_, content))) => TagType::Adjacent { tag, content },
         (Some((untagged_tokens, _)), Some((tag_tokens, _)), Some((content_tokens, _))) => {
             cx.error_spanned_by(
                 untagged_tokens,
@@ -1383,7 +1380,7 @@ impl Field {
                 let expr = syn::ExprPath {
                     attrs: Vec::new(),
                     qself: None,
-                    path: path,
+                    path,
                 };
                 deserialize_with.set_if_none(expr);
             } else if is_cow(&field.ty, is_slice_u8) {
@@ -1400,7 +1397,7 @@ impl Field {
                 let expr = syn::ExprPath {
                     attrs: Vec::new(),
                     qself: None,
-                    path: path,
+                    path,
                 };
                 deserialize_with.set_if_none(expr);
             }
@@ -1420,7 +1417,7 @@ impl Field {
             deserialize_with: deserialize_with.get(),
             ser_bound: ser_bound.get(),
             de_bound: de_bound.get(),
-            borrowed_lifetimes: borrowed_lifetimes,
+            borrowed_lifetimes,
             getter: getter.get(),
             flatten: flatten.get(),
             transparent: false,

serde_derive/src/lib.rs

@@ -13,43 +13,38 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.103")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.109")]
 #![allow(unknown_lints, bare_trait_objects)]
-#![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
-#![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
+#![deny(clippy::all, clippy::pedantic)]
 // Ignored clippy lints
-#![cfg_attr(
-    feature = "cargo-clippy",
-    allow(
-        cognitive_complexity,
-        enum_variant_names,
-        needless_pass_by_value,
-        redundant_field_names,
-        too_many_arguments,
-        trivially_copy_pass_by_ref,
-        used_underscore_binding,
-    )
+#![allow(
+    clippy::cognitive_complexity,
+    clippy::enum_variant_names,
+    clippy::needless_pass_by_value,
+    clippy::too_many_arguments,
+    clippy::trivially_copy_pass_by_ref,
+    clippy::used_underscore_binding,
+    clippy::wildcard_in_or_patterns
 )]
 // Ignored clippy_pedantic lints
-#![cfg_attr(
-    feature = "cargo-clippy",
-    allow(
-        cast_possible_truncation,
-        checked_conversions,
-        doc_markdown,
-        enum_glob_use,
-        filter_map,
-        indexing_slicing,
-        items_after_statements,
-        match_same_arms,
-        module_name_repetitions,
-        must_use_candidate,
-        similar_names,
-        single_match_else,
-        too_many_lines,
-        unseparated_literal_suffix,
-        use_self,
-    )
+#![allow(
+    clippy::cast_possible_truncation,
+    clippy::checked_conversions,
+    clippy::doc_markdown,
+    clippy::enum_glob_use,
+    clippy::filter_map,
+    clippy::indexing_slicing,
+    clippy::items_after_statements,
+    clippy::match_same_arms,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::single_match_else,
+    clippy::struct_excessive_bools,
+    clippy::too_many_lines,
+    clippy::unseparated_literal_suffix,
+    clippy::use_self,
+    clippy::wildcard_imports
 )]
 // The `quote!` macro requires deep recursion.
 #![recursion_limit = "512"]

serde_derive/src/ser.rs

@@ -106,10 +106,10 @@ impl Parameters {
         let generics = build_generics(cont);
 
         Parameters {
-            self_var: self_var,
-            this: this,
-            generics: generics,
-            is_remote: is_remote,
+            self_var,
+            this,
+            generics,
+            is_remote,
         }
     }
 
@@ -538,17 +538,17 @@ fn serialize_externally_tagged_variant(
         }
         Style::Tuple => serialize_tuple_variant(
             TupleVariant::ExternallyTagged {
-                type_name: type_name,
-                variant_index: variant_index,
-                variant_name: variant_name,
+                type_name,
+                variant_index,
+                variant_name,
             },
             params,
             &variant.fields,
         ),
         Style::Struct => serialize_struct_variant(
             StructVariant::ExternallyTagged {
-                variant_index: variant_index,
-                variant_name: variant_name,
+                variant_index,
+                variant_name,
             },
             params,
             &variant.fields,
@@ -614,10 +614,7 @@ fn serialize_internally_tagged_variant(
             }
         }
         Style::Struct => serialize_struct_variant(
-            StructVariant::InternallyTagged {
-                tag: tag,
-                variant_name: variant_name,
-            },
+            StructVariant::InternallyTagged { tag, variant_name },
             params,
             &variant.fields,
             &type_name,
@@ -870,9 +867,9 @@ fn serialize_struct_variant<'a>(
     }
 
     let struct_trait = match context {
-        StructVariant::ExternallyTagged { .. } => (StructTrait::SerializeStructVariant),
+        StructVariant::ExternallyTagged { .. } => StructTrait::SerializeStructVariant,
         StructVariant::InternallyTagged { .. } | StructVariant::Untagged => {
-            (StructTrait::SerializeStruct)
+            StructTrait::SerializeStruct
         }
     };
 
@@ -1273,9 +1270,15 @@ enum StructTrait {
 impl StructTrait {
     fn serialize_field(&self, span: Span) -> TokenStream {
         match *self {
-            StructTrait::SerializeMap => quote_spanned!(span=> _serde::ser::SerializeMap::serialize_entry),
-            StructTrait::SerializeStruct => quote_spanned!(span=> _serde::ser::SerializeStruct::serialize_field),
-            StructTrait::SerializeStructVariant => quote_spanned!(span=> _serde::ser::SerializeStructVariant::serialize_field),
+            StructTrait::SerializeMap => {
+                quote_spanned!(span=> _serde::ser::SerializeMap::serialize_entry)
+            }
+            StructTrait::SerializeStruct => {
+                quote_spanned!(span=> _serde::ser::SerializeStruct::serialize_field)
+            }
+            StructTrait::SerializeStructVariant => {
+                quote_spanned!(span=> _serde::ser::SerializeStructVariant::serialize_field)
+            }
         }
     }
 
@@ -1301,9 +1304,15 @@ enum TupleTrait {
 impl TupleTrait {
     fn serialize_element(&self, span: Span) -> TokenStream {
         match *self {
-            TupleTrait::SerializeTuple => quote_spanned!(span=> _serde::ser::SerializeTuple::serialize_element),
-            TupleTrait::SerializeTupleStruct => quote_spanned!(span=> _serde::ser::SerializeTupleStruct::serialize_field),
-            TupleTrait::SerializeTupleVariant => quote_spanned!(span=> _serde::ser::SerializeTupleVariant::serialize_field),
+            TupleTrait::SerializeTuple => {
+                quote_spanned!(span=> _serde::ser::SerializeTuple::serialize_element)
+            }
+            TupleTrait::SerializeTupleStruct => {
+                quote_spanned!(span=> _serde::ser::SerializeTupleStruct::serialize_field)
+            }
+            TupleTrait::SerializeTupleVariant => {
+                quote_spanned!(span=> _serde::ser::SerializeTupleVariant::serialize_field)
+            }
         }
     }
 }

serde_derive_internals/Cargo.toml

@@ -18,6 +18,5 @@ proc-macro2 = "1.0"
 quote = "1.0"
 syn = { version = "1.0", default-features = false, features = ["derive", "parsing", "printing", "clone-impls"] }
 
-[badges]
-travis-ci = { repository = "serde-rs/serde" }
-appveyor = { repository = "serde-rs/serde" }
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

serde_derive_internals/lib.rs

@@ -6,7 +6,8 @@
     allow(
         cognitive_complexity,
         redundant_field_names,
-        trivially_copy_pass_by_ref
+        trivially_copy_pass_by_ref,
+        wildcard_in_or_patterns
     )
 )]
 

serde_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_test"
-version = "1.0.103" # remember to update html_root_url
+version = "1.0.109" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Token De/Serializer for testing De/Serialize implementations"
@@ -18,6 +18,5 @@ serde = { version = "1.0.60", path = "../serde" }
 serde = { version = "1.0", path = "../serde" }
 serde_derive = { version = "1.0", path = "../serde_derive" }
 
-[badges]
-travis-ci = { repository = "serde-rs/serde" }
-appveyor = { repository = "serde-rs/serde" }
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

serde_test/src/lib.rs

@@ -144,7 +144,7 @@
 //! # }
 //! ```
 
-#![doc(html_root_url = "https://docs.rs/serde_test/1.0.103")]
+#![doc(html_root_url = "https://docs.rs/serde_test/1.0.109")]
 #![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Ignored clippy lints

test_suite/Cargo.toml

@@ -4,16 +4,22 @@ version = "0.0.0"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 edition = "2018"
 publish = false
+build = "build.rs"
 
 [features]
+expandtest = []
 unstable = ["serde/unstable"]
 
 [dependencies]
 serde = { path = "../serde" }
 
+[build-dependencies]
+toolchain_find = "0.1"
+
 [dev-dependencies]
 fnv = "1.0"
-rustversion = "0.1"
+macrotest = "=1.0.0"
+rustversion = "1.0"
 serde = { path = "../serde", features = ["rc", "derive"] }
 serde_derive = { path = "../serde_derive", features = ["deserialize_in_place"] }
 serde_test = { path = "../serde_test" }

test_suite/build.rs

@@ -0,0 +1,29 @@
+use std::process::{Command, ExitStatus, Stdio};
+
+fn has_cargo_expand() -> bool {
+    let cargo_expand = if cfg!(windows) {
+        "cargo-expand.exe"
+    } else {
+        "cargo-expand"
+    };
+
+    Command::new(cargo_expand)
+        .arg("--version")
+        .stdin(Stdio::null())
+        .stdout(Stdio::null())
+        .stderr(Stdio::null())
+        .status()
+        .as_ref()
+        .map(ExitStatus::success)
+        .unwrap_or(false)
+}
+
+fn has_rustfmt() -> bool {
+    toolchain_find::find_installed_component("rustfmt").is_some()
+}
+
+fn main() {
+    if cfg!(feature = "expandtest") && has_cargo_expand() && has_rustfmt() {
+        println!("cargo:rustc-cfg=expandtest");
+    }
+}

test_suite/tests/compiletest.rs

@@ -1,4 +1,4 @@
-#[cfg(not(target_os = "emscripten"))]
+#[cfg_attr(target_os = "emscripten", ignore)]
 #[rustversion::attr(not(nightly), ignore)]
 #[test]
 fn ui() {

test_suite/tests/expand/de_enum.rs

@@ -0,0 +1,13 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+enum DeEnum<B, C, D> {
+    Unit,
+    Seq(i8, B, C, D),
+    Map { a: i8, b: B, c: C, d: D },
+
+    // Make sure we can support more than one variant.
+    _Unit2,
+    _Seq2(i8, B, C, D),
+    _Map2 { a: i8, b: B, c: C, d: D },
+}

test_suite/tests/expand/default_ty_param.expanded.rs

@@ -0,0 +1,401 @@
+use serde::{Deserialize, Serialize};
+trait AssociatedType {
+    type X;
+}
+impl AssociatedType for i32 {
+    type X = i32;
+}
+struct DefaultTyParam<T: AssociatedType<X = i32> = i32> {
+    phantom: PhantomData<T>,
+}
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_DefaultTyParam: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<T: AssociatedType<X = i32>> _serde::Serialize for DefaultTyParam<T> {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            let mut __serde_state = match _serde::Serializer::serialize_struct(
+                __serializer,
+                "DefaultTyParam",
+                false as usize + 1,
+            ) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            match _serde::ser::SerializeStruct::serialize_field(
+                &mut __serde_state,
+                "phantom",
+                &self.phantom,
+            ) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            _serde::ser::SerializeStruct::end(__serde_state)
+        }
+    }
+};
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_DefaultTyParam: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de, T: AssociatedType<X = i32>> _serde::Deserialize<'de> for DefaultTyParam<T> {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {
+                __field0,
+                __ignore,
+            }
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "field identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        0u64 => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"field index 0 <= i < 1",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        "phantom" => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        b"phantom" => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de, T: AssociatedType<X = i32>> {
+                marker: _serde::export::PhantomData<DefaultTyParam<T>>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, T: AssociatedType<X = i32>> _serde::de::Visitor<'de> for __Visitor<'de, T> {
+                type Value = DefaultTyParam<T>;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "struct DefaultTyParam")
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    let __field0 = match match _serde::de::SeqAccess::next_element::<PhantomData<T>>(
+                        &mut __seq,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                0usize,
+                                &"struct DefaultTyParam with 1 element",
+                            ));
+                        }
+                    };
+                    _serde::export::Ok(DefaultTyParam { phantom: __field0 })
+                }
+                #[inline]
+                fn visit_map<__A>(
+                    self,
+                    mut __map: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::MapAccess<'de>,
+                {
+                    let mut __field0: _serde::export::Option<PhantomData<T>> = _serde::export::None;
+                    while let _serde::export::Some(__key) =
+                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map) {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        }
+                    {
+                        match __key {
+                            __Field::__field0 => {
+                                if _serde::export::Option::is_some(&__field0) {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field(
+                                            "phantom",
+                                        ),
+                                    );
+                                }
+                                __field0 = _serde::export::Some(
+                                    match _serde::de::MapAccess::next_value::<PhantomData<T>>(
+                                        &mut __map,
+                                    ) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    },
+                                );
+                            }
+                            _ => {
+                                let _ = match _serde::de::MapAccess::next_value::<
+                                    _serde::de::IgnoredAny,
+                                >(&mut __map)
+                                {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                            }
+                        }
+                    }
+                    let __field0 = match __field0 {
+                        _serde::export::Some(__field0) => __field0,
+                        _serde::export::None => match _serde::private::de::missing_field("phantom")
+                        {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        },
+                    };
+                    _serde::export::Ok(DefaultTyParam { phantom: __field0 })
+                }
+            }
+            const FIELDS: &'static [&'static str] = &["phantom"];
+            _serde::Deserializer::deserialize_struct(
+                __deserializer,
+                "DefaultTyParam",
+                FIELDS,
+                __Visitor {
+                    marker: _serde::export::PhantomData::<DefaultTyParam<T>>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+        fn deserialize_in_place<__D>(
+            __deserializer: __D,
+            __place: &mut Self,
+        ) -> _serde::export::Result<(), __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {
+                __field0,
+                __ignore,
+            }
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "field identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        0u64 => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"field index 0 <= i < 1",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        "phantom" => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        b"phantom" => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de, 'place, T: AssociatedType<X = i32> + 'place> {
+                place: &'place mut DefaultTyParam<T>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, 'place, T: AssociatedType<X = i32> + 'place> _serde::de::Visitor<'de>
+                for __Visitor<'de, 'place, T>
+            {
+                type Value = ();
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "struct DefaultTyParam")
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.phantom),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            0usize,
+                            &"struct DefaultTyParam with 1 element",
+                        ));
+                    }
+                    _serde::export::Ok(())
+                }
+                #[inline]
+                fn visit_map<__A>(
+                    self,
+                    mut __map: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::MapAccess<'de>,
+                {
+                    let mut __field0: bool = false;
+                    while let _serde::export::Some(__key) =
+                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map) {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        }
+                    {
+                        match __key {
+                            __Field::__field0 => {
+                                if __field0 {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field(
+                                            "phantom",
+                                        ),
+                                    );
+                                }
+                                match _serde::de::MapAccess::next_value_seed(
+                                    &mut __map,
+                                    _serde::private::de::InPlaceSeed(&mut self.place.phantom),
+                                ) {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                                __field0 = true;
+                            }
+                            _ => {
+                                let _ = match _serde::de::MapAccess::next_value::<
+                                    _serde::de::IgnoredAny,
+                                >(&mut __map)
+                                {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                            }
+                        }
+                    }
+                    if !__field0 {
+                        self.place.phantom = match _serde::private::de::missing_field("phantom") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        };
+                    };
+                    _serde::export::Ok(())
+                }
+            }
+            const FIELDS: &'static [&'static str] = &["phantom"];
+            _serde::Deserializer::deserialize_struct(
+                __deserializer,
+                "DefaultTyParam",
+                FIELDS,
+                __Visitor {
+                    place: __place,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};

test_suite/tests/expand/default_ty_param.rs

@@ -0,0 +1,14 @@
+use serde::{Deserialize, Serialize};
+
+trait AssociatedType {
+    type X;
+}
+
+impl AssociatedType for i32 {
+    type X = i32;
+}
+
+#[derive(Serialize, Deserialize)]
+struct DefaultTyParam<T: AssociatedType<X = i32> = i32> {
+    phantom: PhantomData<T>,
+}

test_suite/tests/expand/generic_enum.expanded.rs

@@ -0,0 +1,582 @@
+use serde::{Deserialize, Serialize};
+pub enum GenericEnum<T, U> {
+    Unit,
+    NewType(T),
+    Seq(T, U),
+    Map { x: T, y: U },
+}
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_GenericEnum: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<T, U> _serde::Serialize for GenericEnum<T, U>
+    where
+        T: _serde::Serialize,
+        U: _serde::Serialize,
+    {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            match *self {
+                GenericEnum::Unit => _serde::Serializer::serialize_unit_variant(
+                    __serializer,
+                    "GenericEnum",
+                    0u32,
+                    "Unit",
+                ),
+                GenericEnum::NewType(ref __field0) => {
+                    _serde::Serializer::serialize_newtype_variant(
+                        __serializer,
+                        "GenericEnum",
+                        1u32,
+                        "NewType",
+                        __field0,
+                    )
+                }
+                GenericEnum::Seq(ref __field0, ref __field1) => {
+                    let mut __serde_state = match _serde::Serializer::serialize_tuple_variant(
+                        __serializer,
+                        "GenericEnum",
+                        2u32,
+                        "Seq",
+                        0 + 1 + 1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field0,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::ser::SerializeTupleVariant::end(__serde_state)
+                }
+                GenericEnum::Map { ref x, ref y } => {
+                    let mut __serde_state = match _serde::Serializer::serialize_struct_variant(
+                        __serializer,
+                        "GenericEnum",
+                        3u32,
+                        "Map",
+                        0 + 1 + 1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "x",
+                        x,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "y",
+                        y,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::ser::SerializeStructVariant::end(__serde_state)
+                }
+            }
+        }
+    }
+};
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_GenericEnum: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de, T, U> _serde::Deserialize<'de> for GenericEnum<T, U>
+    where
+        T: _serde::Deserialize<'de>,
+        U: _serde::Deserialize<'de>,
+    {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {
+                __field0,
+                __field1,
+                __field2,
+                __field3,
+            }
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "variant identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        0u64 => _serde::export::Ok(__Field::__field0),
+                        1u64 => _serde::export::Ok(__Field::__field1),
+                        2u64 => _serde::export::Ok(__Field::__field2),
+                        3u64 => _serde::export::Ok(__Field::__field3),
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"variant index 0 <= i < 4",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        "Unit" => _serde::export::Ok(__Field::__field0),
+                        "NewType" => _serde::export::Ok(__Field::__field1),
+                        "Seq" => _serde::export::Ok(__Field::__field2),
+                        "Map" => _serde::export::Ok(__Field::__field3),
+                        _ => _serde::export::Err(_serde::de::Error::unknown_variant(
+                            __value, VARIANTS,
+                        )),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        b"Unit" => _serde::export::Ok(__Field::__field0),
+                        b"NewType" => _serde::export::Ok(__Field::__field1),
+                        b"Seq" => _serde::export::Ok(__Field::__field2),
+                        b"Map" => _serde::export::Ok(__Field::__field3),
+                        _ => {
+                            let __value = &_serde::export::from_utf8_lossy(__value);
+                            _serde::export::Err(_serde::de::Error::unknown_variant(
+                                __value, VARIANTS,
+                            ))
+                        }
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de, T, U>
+            where
+                T: _serde::Deserialize<'de>,
+                U: _serde::Deserialize<'de>,
+            {
+                marker: _serde::export::PhantomData<GenericEnum<T, U>>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, T, U> _serde::de::Visitor<'de> for __Visitor<'de, T, U>
+            where
+                T: _serde::Deserialize<'de>,
+                U: _serde::Deserialize<'de>,
+            {
+                type Value = GenericEnum<T, U>;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "enum GenericEnum")
+                }
+                fn visit_enum<__A>(
+                    self,
+                    __data: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::EnumAccess<'de>,
+                {
+                    match match _serde::de::EnumAccess::variant(__data) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        (__Field::__field0, __variant) => {
+                            match _serde::de::VariantAccess::unit_variant(__variant) {
+                                _serde::export::Ok(__val) => __val,
+                                _serde::export::Err(__err) => {
+                                    return _serde::export::Err(__err);
+                                }
+                            };
+                            _serde::export::Ok(GenericEnum::Unit)
+                        }
+                        (__Field::__field1, __variant) => _serde::export::Result::map(
+                            _serde::de::VariantAccess::newtype_variant::<T>(__variant),
+                            GenericEnum::NewType,
+                        ),
+                        (__Field::__field2, __variant) => {
+                            struct __Visitor<'de, T, U>
+                            where
+                                T: _serde::Deserialize<'de>,
+                                U: _serde::Deserialize<'de>,
+                            {
+                                marker: _serde::export::PhantomData<GenericEnum<T, U>>,
+                                lifetime: _serde::export::PhantomData<&'de ()>,
+                            }
+                            impl<'de, T, U> _serde::de::Visitor<'de> for __Visitor<'de, T, U>
+                            where
+                                T: _serde::Deserialize<'de>,
+                                U: _serde::Deserialize<'de>,
+                            {
+                                type Value = GenericEnum<T, U>;
+                                fn expecting(
+                                    &self,
+                                    __formatter: &mut _serde::export::Formatter,
+                                ) -> _serde::export::fmt::Result {
+                                    _serde::export::Formatter::write_str(
+                                        __formatter,
+                                        "tuple variant GenericEnum::Seq",
+                                    )
+                                }
+                                #[inline]
+                                fn visit_seq<__A>(
+                                    self,
+                                    mut __seq: __A,
+                                ) -> _serde::export::Result<Self::Value, __A::Error>
+                                where
+                                    __A: _serde::de::SeqAccess<'de>,
+                                {
+                                    let __field0 = match match _serde::de::SeqAccess::next_element::<
+                                        T,
+                                    >(
+                                        &mut __seq
+                                    ) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    } {
+                                        _serde::export::Some(__value) => __value,
+                                        _serde::export::None => {
+                                            return _serde :: export :: Err ( _serde :: de :: Error :: invalid_length ( 0usize , & "tuple variant GenericEnum::Seq with 2 elements" ) ) ;
+                                        }
+                                    };
+                                    let __field1 = match match _serde::de::SeqAccess::next_element::<
+                                        U,
+                                    >(
+                                        &mut __seq
+                                    ) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    } {
+                                        _serde::export::Some(__value) => __value,
+                                        _serde::export::None => {
+                                            return _serde :: export :: Err ( _serde :: de :: Error :: invalid_length ( 1usize , & "tuple variant GenericEnum::Seq with 2 elements" ) ) ;
+                                        }
+                                    };
+                                    _serde::export::Ok(GenericEnum::Seq(__field0, __field1))
+                                }
+                            }
+                            _serde::de::VariantAccess::tuple_variant(
+                                __variant,
+                                2usize,
+                                __Visitor {
+                                    marker: _serde::export::PhantomData::<GenericEnum<T, U>>,
+                                    lifetime: _serde::export::PhantomData,
+                                },
+                            )
+                        }
+                        (__Field::__field3, __variant) => {
+                            #[allow(non_camel_case_types)]
+                            enum __Field {
+                                __field0,
+                                __field1,
+                                __ignore,
+                            }
+                            struct __FieldVisitor;
+                            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                                type Value = __Field;
+                                fn expecting(
+                                    &self,
+                                    __formatter: &mut _serde::export::Formatter,
+                                ) -> _serde::export::fmt::Result {
+                                    _serde::export::Formatter::write_str(
+                                        __formatter,
+                                        "field identifier",
+                                    )
+                                }
+                                fn visit_u64<__E>(
+                                    self,
+                                    __value: u64,
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        0u64 => _serde::export::Ok(__Field::__field0),
+                                        1u64 => _serde::export::Ok(__Field::__field1),
+                                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                                            _serde::de::Unexpected::Unsigned(__value),
+                                            &"field index 0 <= i < 2",
+                                        )),
+                                    }
+                                }
+                                fn visit_str<__E>(
+                                    self,
+                                    __value: &str,
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        "x" => _serde::export::Ok(__Field::__field0),
+                                        "y" => _serde::export::Ok(__Field::__field1),
+                                        _ => _serde::export::Ok(__Field::__ignore),
+                                    }
+                                }
+                                fn visit_bytes<__E>(
+                                    self,
+                                    __value: &[u8],
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        b"x" => _serde::export::Ok(__Field::__field0),
+                                        b"y" => _serde::export::Ok(__Field::__field1),
+                                        _ => _serde::export::Ok(__Field::__ignore),
+                                    }
+                                }
+                            }
+                            impl<'de> _serde::Deserialize<'de> for __Field {
+                                #[inline]
+                                fn deserialize<__D>(
+                                    __deserializer: __D,
+                                ) -> _serde::export::Result<Self, __D::Error>
+                                where
+                                    __D: _serde::Deserializer<'de>,
+                                {
+                                    _serde::Deserializer::deserialize_identifier(
+                                        __deserializer,
+                                        __FieldVisitor,
+                                    )
+                                }
+                            }
+                            struct __Visitor<'de, T, U>
+                            where
+                                T: _serde::Deserialize<'de>,
+                                U: _serde::Deserialize<'de>,
+                            {
+                                marker: _serde::export::PhantomData<GenericEnum<T, U>>,
+                                lifetime: _serde::export::PhantomData<&'de ()>,
+                            }
+                            impl<'de, T, U> _serde::de::Visitor<'de> for __Visitor<'de, T, U>
+                            where
+                                T: _serde::Deserialize<'de>,
+                                U: _serde::Deserialize<'de>,
+                            {
+                                type Value = GenericEnum<T, U>;
+                                fn expecting(
+                                    &self,
+                                    __formatter: &mut _serde::export::Formatter,
+                                ) -> _serde::export::fmt::Result {
+                                    _serde::export::Formatter::write_str(
+                                        __formatter,
+                                        "struct variant GenericEnum::Map",
+                                    )
+                                }
+                                #[inline]
+                                fn visit_seq<__A>(
+                                    self,
+                                    mut __seq: __A,
+                                ) -> _serde::export::Result<Self::Value, __A::Error>
+                                where
+                                    __A: _serde::de::SeqAccess<'de>,
+                                {
+                                    let __field0 = match match _serde::de::SeqAccess::next_element::<
+                                        T,
+                                    >(
+                                        &mut __seq
+                                    ) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    } {
+                                        _serde::export::Some(__value) => __value,
+                                        _serde::export::None => {
+                                            return _serde :: export :: Err ( _serde :: de :: Error :: invalid_length ( 0usize , & "struct variant GenericEnum::Map with 2 elements" ) ) ;
+                                        }
+                                    };
+                                    let __field1 = match match _serde::de::SeqAccess::next_element::<
+                                        U,
+                                    >(
+                                        &mut __seq
+                                    ) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    } {
+                                        _serde::export::Some(__value) => __value,
+                                        _serde::export::None => {
+                                            return _serde :: export :: Err ( _serde :: de :: Error :: invalid_length ( 1usize , & "struct variant GenericEnum::Map with 2 elements" ) ) ;
+                                        }
+                                    };
+                                    _serde::export::Ok(GenericEnum::Map {
+                                        x: __field0,
+                                        y: __field1,
+                                    })
+                                }
+                                #[inline]
+                                fn visit_map<__A>(
+                                    self,
+                                    mut __map: __A,
+                                ) -> _serde::export::Result<Self::Value, __A::Error>
+                                where
+                                    __A: _serde::de::MapAccess<'de>,
+                                {
+                                    let mut __field0: _serde::export::Option<T> =
+                                        _serde::export::None;
+                                    let mut __field1: _serde::export::Option<U> =
+                                        _serde::export::None;
+                                    while let _serde::export::Some(__key) =
+                                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map)
+                                        {
+                                            _serde::export::Ok(__val) => __val,
+                                            _serde::export::Err(__err) => {
+                                                return _serde::export::Err(__err);
+                                            }
+                                        }
+                                    {
+                                        match __key {
+                                            __Field::__field0 => {
+                                                if _serde::export::Option::is_some(&__field0) {
+                                                    return _serde :: export :: Err ( < __A :: Error as _serde :: de :: Error > :: duplicate_field ( "x" ) ) ;
+                                                }
+                                                __field0 = _serde::export::Some(
+                                                    match _serde::de::MapAccess::next_value::<T>(
+                                                        &mut __map,
+                                                    ) {
+                                                        _serde::export::Ok(__val) => __val,
+                                                        _serde::export::Err(__err) => {
+                                                            return _serde::export::Err(__err);
+                                                        }
+                                                    },
+                                                );
+                                            }
+                                            __Field::__field1 => {
+                                                if _serde::export::Option::is_some(&__field1) {
+                                                    return _serde :: export :: Err ( < __A :: Error as _serde :: de :: Error > :: duplicate_field ( "y" ) ) ;
+                                                }
+                                                __field1 = _serde::export::Some(
+                                                    match _serde::de::MapAccess::next_value::<U>(
+                                                        &mut __map,
+                                                    ) {
+                                                        _serde::export::Ok(__val) => __val,
+                                                        _serde::export::Err(__err) => {
+                                                            return _serde::export::Err(__err);
+                                                        }
+                                                    },
+                                                );
+                                            }
+                                            _ => {
+                                                let _ = match _serde::de::MapAccess::next_value::<
+                                                    _serde::de::IgnoredAny,
+                                                >(
+                                                    &mut __map
+                                                ) {
+                                                    _serde::export::Ok(__val) => __val,
+                                                    _serde::export::Err(__err) => {
+                                                        return _serde::export::Err(__err);
+                                                    }
+                                                };
+                                            }
+                                        }
+                                    }
+                                    let __field0 = match __field0 {
+                                        _serde::export::Some(__field0) => __field0,
+                                        _serde::export::None => {
+                                            match _serde::private::de::missing_field("x") {
+                                                _serde::export::Ok(__val) => __val,
+                                                _serde::export::Err(__err) => {
+                                                    return _serde::export::Err(__err);
+                                                }
+                                            }
+                                        }
+                                    };
+                                    let __field1 = match __field1 {
+                                        _serde::export::Some(__field1) => __field1,
+                                        _serde::export::None => {
+                                            match _serde::private::de::missing_field("y") {
+                                                _serde::export::Ok(__val) => __val,
+                                                _serde::export::Err(__err) => {
+                                                    return _serde::export::Err(__err);
+                                                }
+                                            }
+                                        }
+                                    };
+                                    _serde::export::Ok(GenericEnum::Map {
+                                        x: __field0,
+                                        y: __field1,
+                                    })
+                                }
+                            }
+                            const FIELDS: &'static [&'static str] = &["x", "y"];
+                            _serde::de::VariantAccess::struct_variant(
+                                __variant,
+                                FIELDS,
+                                __Visitor {
+                                    marker: _serde::export::PhantomData::<GenericEnum<T, U>>,
+                                    lifetime: _serde::export::PhantomData,
+                                },
+                            )
+                        }
+                    }
+                }
+            }
+            const VARIANTS: &'static [&'static str] = &["Unit", "NewType", "Seq", "Map"];
+            _serde::Deserializer::deserialize_enum(
+                __deserializer,
+                "GenericEnum",
+                VARIANTS,
+                __Visitor {
+                    marker: _serde::export::PhantomData::<GenericEnum<T, U>>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};

test_suite/tests/expand/generic_enum.rs

@@ -0,0 +1,9 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+pub enum GenericEnum<T, U> {
+    Unit,
+    NewType(T),
+    Seq(T, U),
+    Map { x: T, y: U },
+}

test_suite/tests/expand/generic_struct.expanded.rs

@@ -0,0 +1,582 @@
+use serde::{Deserialize, Serialize};
+pub struct GenericStruct<T> {
+    x: T,
+}
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_GenericStruct: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<T> _serde::Serialize for GenericStruct<T>
+    where
+        T: _serde::Serialize,
+    {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            let mut __serde_state = match _serde::Serializer::serialize_struct(
+                __serializer,
+                "GenericStruct",
+                false as usize + 1,
+            ) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            match _serde::ser::SerializeStruct::serialize_field(&mut __serde_state, "x", &self.x) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            _serde::ser::SerializeStruct::end(__serde_state)
+        }
+    }
+};
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_GenericStruct: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de, T> _serde::Deserialize<'de> for GenericStruct<T>
+    where
+        T: _serde::Deserialize<'de>,
+    {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {
+                __field0,
+                __ignore,
+            }
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "field identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        0u64 => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"field index 0 <= i < 1",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        "x" => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        b"x" => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de, T>
+            where
+                T: _serde::Deserialize<'de>,
+            {
+                marker: _serde::export::PhantomData<GenericStruct<T>>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, T> _serde::de::Visitor<'de> for __Visitor<'de, T>
+            where
+                T: _serde::Deserialize<'de>,
+            {
+                type Value = GenericStruct<T>;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "struct GenericStruct")
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    let __field0 = match match _serde::de::SeqAccess::next_element::<T>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                0usize,
+                                &"struct GenericStruct with 1 element",
+                            ));
+                        }
+                    };
+                    _serde::export::Ok(GenericStruct { x: __field0 })
+                }
+                #[inline]
+                fn visit_map<__A>(
+                    self,
+                    mut __map: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::MapAccess<'de>,
+                {
+                    let mut __field0: _serde::export::Option<T> = _serde::export::None;
+                    while let _serde::export::Some(__key) =
+                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map) {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        }
+                    {
+                        match __key {
+                            __Field::__field0 => {
+                                if _serde::export::Option::is_some(&__field0) {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field("x"),
+                                    );
+                                }
+                                __field0 = _serde::export::Some(
+                                    match _serde::de::MapAccess::next_value::<T>(&mut __map) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    },
+                                );
+                            }
+                            _ => {
+                                let _ = match _serde::de::MapAccess::next_value::<
+                                    _serde::de::IgnoredAny,
+                                >(&mut __map)
+                                {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                            }
+                        }
+                    }
+                    let __field0 = match __field0 {
+                        _serde::export::Some(__field0) => __field0,
+                        _serde::export::None => match _serde::private::de::missing_field("x") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        },
+                    };
+                    _serde::export::Ok(GenericStruct { x: __field0 })
+                }
+            }
+            const FIELDS: &'static [&'static str] = &["x"];
+            _serde::Deserializer::deserialize_struct(
+                __deserializer,
+                "GenericStruct",
+                FIELDS,
+                __Visitor {
+                    marker: _serde::export::PhantomData::<GenericStruct<T>>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+        fn deserialize_in_place<__D>(
+            __deserializer: __D,
+            __place: &mut Self,
+        ) -> _serde::export::Result<(), __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {
+                __field0,
+                __ignore,
+            }
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "field identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        0u64 => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"field index 0 <= i < 1",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        "x" => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        b"x" => _serde::export::Ok(__Field::__field0),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de, 'place, T: 'place>
+            where
+                T: _serde::Deserialize<'de>,
+            {
+                place: &'place mut GenericStruct<T>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, 'place, T: 'place> _serde::de::Visitor<'de> for __Visitor<'de, 'place, T>
+            where
+                T: _serde::Deserialize<'de>,
+            {
+                type Value = ();
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "struct GenericStruct")
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.x),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            0usize,
+                            &"struct GenericStruct with 1 element",
+                        ));
+                    }
+                    _serde::export::Ok(())
+                }
+                #[inline]
+                fn visit_map<__A>(
+                    self,
+                    mut __map: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::MapAccess<'de>,
+                {
+                    let mut __field0: bool = false;
+                    while let _serde::export::Some(__key) =
+                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map) {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        }
+                    {
+                        match __key {
+                            __Field::__field0 => {
+                                if __field0 {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field("x"),
+                                    );
+                                }
+                                match _serde::de::MapAccess::next_value_seed(
+                                    &mut __map,
+                                    _serde::private::de::InPlaceSeed(&mut self.place.x),
+                                ) {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                                __field0 = true;
+                            }
+                            _ => {
+                                let _ = match _serde::de::MapAccess::next_value::<
+                                    _serde::de::IgnoredAny,
+                                >(&mut __map)
+                                {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                            }
+                        }
+                    }
+                    if !__field0 {
+                        self.place.x = match _serde::private::de::missing_field("x") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        };
+                    };
+                    _serde::export::Ok(())
+                }
+            }
+            const FIELDS: &'static [&'static str] = &["x"];
+            _serde::Deserializer::deserialize_struct(
+                __deserializer,
+                "GenericStruct",
+                FIELDS,
+                __Visitor {
+                    place: __place,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};
+pub struct GenericNewTypeStruct<T>(T);
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_GenericNewTypeStruct: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<T> _serde::Serialize for GenericNewTypeStruct<T>
+    where
+        T: _serde::Serialize,
+    {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            _serde::Serializer::serialize_newtype_struct(
+                __serializer,
+                "GenericNewTypeStruct",
+                &self.0,
+            )
+        }
+    }
+};
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_GenericNewTypeStruct: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de, T> _serde::Deserialize<'de> for GenericNewTypeStruct<T>
+    where
+        T: _serde::Deserialize<'de>,
+    {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            struct __Visitor<'de, T>
+            where
+                T: _serde::Deserialize<'de>,
+            {
+                marker: _serde::export::PhantomData<GenericNewTypeStruct<T>>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, T> _serde::de::Visitor<'de> for __Visitor<'de, T>
+            where
+                T: _serde::Deserialize<'de>,
+            {
+                type Value = GenericNewTypeStruct<T>;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(
+                        __formatter,
+                        "tuple struct GenericNewTypeStruct",
+                    )
+                }
+                #[inline]
+                fn visit_newtype_struct<__E>(
+                    self,
+                    __e: __E,
+                ) -> _serde::export::Result<Self::Value, __E::Error>
+                where
+                    __E: _serde::Deserializer<'de>,
+                {
+                    let __field0: T = match <T as _serde::Deserialize>::deserialize(__e) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::export::Ok(GenericNewTypeStruct(__field0))
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    let __field0 = match match _serde::de::SeqAccess::next_element::<T>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                0usize,
+                                &"tuple struct GenericNewTypeStruct with 1 element",
+                            ));
+                        }
+                    };
+                    _serde::export::Ok(GenericNewTypeStruct(__field0))
+                }
+            }
+            _serde::Deserializer::deserialize_newtype_struct(
+                __deserializer,
+                "GenericNewTypeStruct",
+                __Visitor {
+                    marker: _serde::export::PhantomData::<GenericNewTypeStruct<T>>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+        fn deserialize_in_place<__D>(
+            __deserializer: __D,
+            __place: &mut Self,
+        ) -> _serde::export::Result<(), __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            struct __Visitor<'de, 'place, T: 'place>
+            where
+                T: _serde::Deserialize<'de>,
+            {
+                place: &'place mut GenericNewTypeStruct<T>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, 'place, T: 'place> _serde::de::Visitor<'de> for __Visitor<'de, 'place, T>
+            where
+                T: _serde::Deserialize<'de>,
+            {
+                type Value = ();
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(
+                        __formatter,
+                        "tuple struct GenericNewTypeStruct",
+                    )
+                }
+                #[inline]
+                fn visit_newtype_struct<__E>(
+                    self,
+                    __e: __E,
+                ) -> _serde::export::Result<Self::Value, __E::Error>
+                where
+                    __E: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserialize::deserialize_in_place(__e, &mut self.place.0)
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.0),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            0usize,
+                            &"tuple struct GenericNewTypeStruct with 1 element",
+                        ));
+                    }
+                    _serde::export::Ok(())
+                }
+            }
+            _serde::Deserializer::deserialize_newtype_struct(
+                __deserializer,
+                "GenericNewTypeStruct",
+                __Visitor {
+                    place: __place,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};

test_suite/tests/expand/generic_struct.rs

@@ -0,0 +1,9 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+pub struct GenericStruct<T> {
+    x: T,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct GenericNewTypeStruct<T>(T);

test_suite/tests/expand/generic_tuple_struct.expanded.rs

@@ -0,0 +1,172 @@
+use serde::{Deserialize, Serialize};
+pub struct GenericTupleStruct<T, U>(T, U);
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_GenericTupleStruct: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de, T, U> _serde::Deserialize<'de> for GenericTupleStruct<T, U>
+    where
+        T: _serde::Deserialize<'de>,
+        U: _serde::Deserialize<'de>,
+    {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            struct __Visitor<'de, T, U>
+            where
+                T: _serde::Deserialize<'de>,
+                U: _serde::Deserialize<'de>,
+            {
+                marker: _serde::export::PhantomData<GenericTupleStruct<T, U>>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, T, U> _serde::de::Visitor<'de> for __Visitor<'de, T, U>
+            where
+                T: _serde::Deserialize<'de>,
+                U: _serde::Deserialize<'de>,
+            {
+                type Value = GenericTupleStruct<T, U>;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(
+                        __formatter,
+                        "tuple struct GenericTupleStruct",
+                    )
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    let __field0 = match match _serde::de::SeqAccess::next_element::<T>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                0usize,
+                                &"tuple struct GenericTupleStruct with 2 elements",
+                            ));
+                        }
+                    };
+                    let __field1 = match match _serde::de::SeqAccess::next_element::<U>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                1usize,
+                                &"tuple struct GenericTupleStruct with 2 elements",
+                            ));
+                        }
+                    };
+                    _serde::export::Ok(GenericTupleStruct(__field0, __field1))
+                }
+            }
+            _serde::Deserializer::deserialize_tuple_struct(
+                __deserializer,
+                "GenericTupleStruct",
+                2usize,
+                __Visitor {
+                    marker: _serde::export::PhantomData::<GenericTupleStruct<T, U>>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+        fn deserialize_in_place<__D>(
+            __deserializer: __D,
+            __place: &mut Self,
+        ) -> _serde::export::Result<(), __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            struct __Visitor<'de, 'place, T: 'place, U: 'place>
+            where
+                T: _serde::Deserialize<'de>,
+                U: _serde::Deserialize<'de>,
+            {
+                place: &'place mut GenericTupleStruct<T, U>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, 'place, T: 'place, U: 'place> _serde::de::Visitor<'de> for __Visitor<'de, 'place, T, U>
+            where
+                T: _serde::Deserialize<'de>,
+                U: _serde::Deserialize<'de>,
+            {
+                type Value = ();
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(
+                        __formatter,
+                        "tuple struct GenericTupleStruct",
+                    )
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.0),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            0usize,
+                            &"tuple struct GenericTupleStruct with 2 elements",
+                        ));
+                    }
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.1),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            1usize,
+                            &"tuple struct GenericTupleStruct with 2 elements",
+                        ));
+                    }
+                    _serde::export::Ok(())
+                }
+            }
+            _serde::Deserializer::deserialize_tuple_struct(
+                __deserializer,
+                "GenericTupleStruct",
+                2usize,
+                __Visitor {
+                    place: __place,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};

test_suite/tests/expand/generic_tuple_struct.rs

@@ -0,0 +1,4 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Deserialize)]
+pub struct GenericTupleStruct<T, U>(T, U);

test_suite/tests/expand/lifetimes.expanded.rs

@@ -0,0 +1,601 @@
+use serde::{Deserialize, Serialize};
+enum Lifetimes<'a> {
+    LifetimeSeq(&'a i32),
+    NoLifetimeSeq(i32),
+    LifetimeMap { a: &'a i32 },
+    NoLifetimeMap { a: i32 },
+}
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_Lifetimes: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'a> _serde::Serialize for Lifetimes<'a> {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            match *self {
+                Lifetimes::LifetimeSeq(ref __field0) => {
+                    _serde::Serializer::serialize_newtype_variant(
+                        __serializer,
+                        "Lifetimes",
+                        0u32,
+                        "LifetimeSeq",
+                        __field0,
+                    )
+                }
+                Lifetimes::NoLifetimeSeq(ref __field0) => {
+                    _serde::Serializer::serialize_newtype_variant(
+                        __serializer,
+                        "Lifetimes",
+                        1u32,
+                        "NoLifetimeSeq",
+                        __field0,
+                    )
+                }
+                Lifetimes::LifetimeMap { ref a } => {
+                    let mut __serde_state = match _serde::Serializer::serialize_struct_variant(
+                        __serializer,
+                        "Lifetimes",
+                        2u32,
+                        "LifetimeMap",
+                        0 + 1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "a",
+                        a,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::ser::SerializeStructVariant::end(__serde_state)
+                }
+                Lifetimes::NoLifetimeMap { ref a } => {
+                    let mut __serde_state = match _serde::Serializer::serialize_struct_variant(
+                        __serializer,
+                        "Lifetimes",
+                        3u32,
+                        "NoLifetimeMap",
+                        0 + 1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "a",
+                        a,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::ser::SerializeStructVariant::end(__serde_state)
+                }
+            }
+        }
+    }
+};
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_Lifetimes: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de, 'a> _serde::Deserialize<'de> for Lifetimes<'a> {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {
+                __field0,
+                __field1,
+                __field2,
+                __field3,
+            }
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "variant identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        0u64 => _serde::export::Ok(__Field::__field0),
+                        1u64 => _serde::export::Ok(__Field::__field1),
+                        2u64 => _serde::export::Ok(__Field::__field2),
+                        3u64 => _serde::export::Ok(__Field::__field3),
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"variant index 0 <= i < 4",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        "LifetimeSeq" => _serde::export::Ok(__Field::__field0),
+                        "NoLifetimeSeq" => _serde::export::Ok(__Field::__field1),
+                        "LifetimeMap" => _serde::export::Ok(__Field::__field2),
+                        "NoLifetimeMap" => _serde::export::Ok(__Field::__field3),
+                        _ => _serde::export::Err(_serde::de::Error::unknown_variant(
+                            __value, VARIANTS,
+                        )),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        b"LifetimeSeq" => _serde::export::Ok(__Field::__field0),
+                        b"NoLifetimeSeq" => _serde::export::Ok(__Field::__field1),
+                        b"LifetimeMap" => _serde::export::Ok(__Field::__field2),
+                        b"NoLifetimeMap" => _serde::export::Ok(__Field::__field3),
+                        _ => {
+                            let __value = &_serde::export::from_utf8_lossy(__value);
+                            _serde::export::Err(_serde::de::Error::unknown_variant(
+                                __value, VARIANTS,
+                            ))
+                        }
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de, 'a> {
+                marker: _serde::export::PhantomData<Lifetimes<'a>>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, 'a> _serde::de::Visitor<'de> for __Visitor<'de, 'a> {
+                type Value = Lifetimes<'a>;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "enum Lifetimes")
+                }
+                fn visit_enum<__A>(
+                    self,
+                    __data: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::EnumAccess<'de>,
+                {
+                    match match _serde::de::EnumAccess::variant(__data) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        (__Field::__field0, __variant) => _serde::export::Result::map(
+                            _serde::de::VariantAccess::newtype_variant::<&'a i32>(__variant),
+                            Lifetimes::LifetimeSeq,
+                        ),
+                        (__Field::__field1, __variant) => _serde::export::Result::map(
+                            _serde::de::VariantAccess::newtype_variant::<i32>(__variant),
+                            Lifetimes::NoLifetimeSeq,
+                        ),
+                        (__Field::__field2, __variant) => {
+                            #[allow(non_camel_case_types)]
+                            enum __Field {
+                                __field0,
+                                __ignore,
+                            }
+                            struct __FieldVisitor;
+                            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                                type Value = __Field;
+                                fn expecting(
+                                    &self,
+                                    __formatter: &mut _serde::export::Formatter,
+                                ) -> _serde::export::fmt::Result {
+                                    _serde::export::Formatter::write_str(
+                                        __formatter,
+                                        "field identifier",
+                                    )
+                                }
+                                fn visit_u64<__E>(
+                                    self,
+                                    __value: u64,
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        0u64 => _serde::export::Ok(__Field::__field0),
+                                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                                            _serde::de::Unexpected::Unsigned(__value),
+                                            &"field index 0 <= i < 1",
+                                        )),
+                                    }
+                                }
+                                fn visit_str<__E>(
+                                    self,
+                                    __value: &str,
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        "a" => _serde::export::Ok(__Field::__field0),
+                                        _ => _serde::export::Ok(__Field::__ignore),
+                                    }
+                                }
+                                fn visit_bytes<__E>(
+                                    self,
+                                    __value: &[u8],
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        b"a" => _serde::export::Ok(__Field::__field0),
+                                        _ => _serde::export::Ok(__Field::__ignore),
+                                    }
+                                }
+                            }
+                            impl<'de> _serde::Deserialize<'de> for __Field {
+                                #[inline]
+                                fn deserialize<__D>(
+                                    __deserializer: __D,
+                                ) -> _serde::export::Result<Self, __D::Error>
+                                where
+                                    __D: _serde::Deserializer<'de>,
+                                {
+                                    _serde::Deserializer::deserialize_identifier(
+                                        __deserializer,
+                                        __FieldVisitor,
+                                    )
+                                }
+                            }
+                            struct __Visitor<'de, 'a> {
+                                marker: _serde::export::PhantomData<Lifetimes<'a>>,
+                                lifetime: _serde::export::PhantomData<&'de ()>,
+                            }
+                            impl<'de, 'a> _serde::de::Visitor<'de> for __Visitor<'de, 'a> {
+                                type Value = Lifetimes<'a>;
+                                fn expecting(
+                                    &self,
+                                    __formatter: &mut _serde::export::Formatter,
+                                ) -> _serde::export::fmt::Result {
+                                    _serde::export::Formatter::write_str(
+                                        __formatter,
+                                        "struct variant Lifetimes::LifetimeMap",
+                                    )
+                                }
+                                #[inline]
+                                fn visit_seq<__A>(
+                                    self,
+                                    mut __seq: __A,
+                                ) -> _serde::export::Result<Self::Value, __A::Error>
+                                where
+                                    __A: _serde::de::SeqAccess<'de>,
+                                {
+                                    let __field0 = match match _serde::de::SeqAccess::next_element::<
+                                        &'a i32,
+                                    >(
+                                        &mut __seq
+                                    ) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    } {
+                                        _serde::export::Some(__value) => __value,
+                                        _serde::export::None => {
+                                            return _serde :: export :: Err ( _serde :: de :: Error :: invalid_length ( 0usize , & "struct variant Lifetimes::LifetimeMap with 1 element" ) ) ;
+                                        }
+                                    };
+                                    _serde::export::Ok(Lifetimes::LifetimeMap { a: __field0 })
+                                }
+                                #[inline]
+                                fn visit_map<__A>(
+                                    self,
+                                    mut __map: __A,
+                                ) -> _serde::export::Result<Self::Value, __A::Error>
+                                where
+                                    __A: _serde::de::MapAccess<'de>,
+                                {
+                                    let mut __field0: _serde::export::Option<&'a i32> =
+                                        _serde::export::None;
+                                    while let _serde::export::Some(__key) =
+                                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map)
+                                        {
+                                            _serde::export::Ok(__val) => __val,
+                                            _serde::export::Err(__err) => {
+                                                return _serde::export::Err(__err);
+                                            }
+                                        }
+                                    {
+                                        match __key {
+                                            __Field::__field0 => {
+                                                if _serde::export::Option::is_some(&__field0) {
+                                                    return _serde :: export :: Err ( < __A :: Error as _serde :: de :: Error > :: duplicate_field ( "a" ) ) ;
+                                                }
+                                                __field0 = _serde::export::Some(
+                                                    match _serde::de::MapAccess::next_value::<&'a i32>(
+                                                        &mut __map,
+                                                    ) {
+                                                        _serde::export::Ok(__val) => __val,
+                                                        _serde::export::Err(__err) => {
+                                                            return _serde::export::Err(__err);
+                                                        }
+                                                    },
+                                                );
+                                            }
+                                            _ => {
+                                                let _ = match _serde::de::MapAccess::next_value::<
+                                                    _serde::de::IgnoredAny,
+                                                >(
+                                                    &mut __map
+                                                ) {
+                                                    _serde::export::Ok(__val) => __val,
+                                                    _serde::export::Err(__err) => {
+                                                        return _serde::export::Err(__err);
+                                                    }
+                                                };
+                                            }
+                                        }
+                                    }
+                                    let __field0 = match __field0 {
+                                        _serde::export::Some(__field0) => __field0,
+                                        _serde::export::None => {
+                                            match _serde::private::de::missing_field("a") {
+                                                _serde::export::Ok(__val) => __val,
+                                                _serde::export::Err(__err) => {
+                                                    return _serde::export::Err(__err);
+                                                }
+                                            }
+                                        }
+                                    };
+                                    _serde::export::Ok(Lifetimes::LifetimeMap { a: __field0 })
+                                }
+                            }
+                            const FIELDS: &'static [&'static str] = &["a"];
+                            _serde::de::VariantAccess::struct_variant(
+                                __variant,
+                                FIELDS,
+                                __Visitor {
+                                    marker: _serde::export::PhantomData::<Lifetimes<'a>>,
+                                    lifetime: _serde::export::PhantomData,
+                                },
+                            )
+                        }
+                        (__Field::__field3, __variant) => {
+                            #[allow(non_camel_case_types)]
+                            enum __Field {
+                                __field0,
+                                __ignore,
+                            }
+                            struct __FieldVisitor;
+                            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                                type Value = __Field;
+                                fn expecting(
+                                    &self,
+                                    __formatter: &mut _serde::export::Formatter,
+                                ) -> _serde::export::fmt::Result {
+                                    _serde::export::Formatter::write_str(
+                                        __formatter,
+                                        "field identifier",
+                                    )
+                                }
+                                fn visit_u64<__E>(
+                                    self,
+                                    __value: u64,
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        0u64 => _serde::export::Ok(__Field::__field0),
+                                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                                            _serde::de::Unexpected::Unsigned(__value),
+                                            &"field index 0 <= i < 1",
+                                        )),
+                                    }
+                                }
+                                fn visit_str<__E>(
+                                    self,
+                                    __value: &str,
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        "a" => _serde::export::Ok(__Field::__field0),
+                                        _ => _serde::export::Ok(__Field::__ignore),
+                                    }
+                                }
+                                fn visit_bytes<__E>(
+                                    self,
+                                    __value: &[u8],
+                                ) -> _serde::export::Result<Self::Value, __E>
+                                where
+                                    __E: _serde::de::Error,
+                                {
+                                    match __value {
+                                        b"a" => _serde::export::Ok(__Field::__field0),
+                                        _ => _serde::export::Ok(__Field::__ignore),
+                                    }
+                                }
+                            }
+                            impl<'de> _serde::Deserialize<'de> for __Field {
+                                #[inline]
+                                fn deserialize<__D>(
+                                    __deserializer: __D,
+                                ) -> _serde::export::Result<Self, __D::Error>
+                                where
+                                    __D: _serde::Deserializer<'de>,
+                                {
+                                    _serde::Deserializer::deserialize_identifier(
+                                        __deserializer,
+                                        __FieldVisitor,
+                                    )
+                                }
+                            }
+                            struct __Visitor<'de, 'a> {
+                                marker: _serde::export::PhantomData<Lifetimes<'a>>,
+                                lifetime: _serde::export::PhantomData<&'de ()>,
+                            }
+                            impl<'de, 'a> _serde::de::Visitor<'de> for __Visitor<'de, 'a> {
+                                type Value = Lifetimes<'a>;
+                                fn expecting(
+                                    &self,
+                                    __formatter: &mut _serde::export::Formatter,
+                                ) -> _serde::export::fmt::Result {
+                                    _serde::export::Formatter::write_str(
+                                        __formatter,
+                                        "struct variant Lifetimes::NoLifetimeMap",
+                                    )
+                                }
+                                #[inline]
+                                fn visit_seq<__A>(
+                                    self,
+                                    mut __seq: __A,
+                                ) -> _serde::export::Result<Self::Value, __A::Error>
+                                where
+                                    __A: _serde::de::SeqAccess<'de>,
+                                {
+                                    let __field0 = match match _serde::de::SeqAccess::next_element::<
+                                        i32,
+                                    >(
+                                        &mut __seq
+                                    ) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    } {
+                                        _serde::export::Some(__value) => __value,
+                                        _serde::export::None => {
+                                            return _serde :: export :: Err ( _serde :: de :: Error :: invalid_length ( 0usize , & "struct variant Lifetimes::NoLifetimeMap with 1 element" ) ) ;
+                                        }
+                                    };
+                                    _serde::export::Ok(Lifetimes::NoLifetimeMap { a: __field0 })
+                                }
+                                #[inline]
+                                fn visit_map<__A>(
+                                    self,
+                                    mut __map: __A,
+                                ) -> _serde::export::Result<Self::Value, __A::Error>
+                                where
+                                    __A: _serde::de::MapAccess<'de>,
+                                {
+                                    let mut __field0: _serde::export::Option<i32> =
+                                        _serde::export::None;
+                                    while let _serde::export::Some(__key) =
+                                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map)
+                                        {
+                                            _serde::export::Ok(__val) => __val,
+                                            _serde::export::Err(__err) => {
+                                                return _serde::export::Err(__err);
+                                            }
+                                        }
+                                    {
+                                        match __key {
+                                            __Field::__field0 => {
+                                                if _serde::export::Option::is_some(&__field0) {
+                                                    return _serde :: export :: Err ( < __A :: Error as _serde :: de :: Error > :: duplicate_field ( "a" ) ) ;
+                                                }
+                                                __field0 = _serde::export::Some(
+                                                    match _serde::de::MapAccess::next_value::<i32>(
+                                                        &mut __map,
+                                                    ) {
+                                                        _serde::export::Ok(__val) => __val,
+                                                        _serde::export::Err(__err) => {
+                                                            return _serde::export::Err(__err);
+                                                        }
+                                                    },
+                                                );
+                                            }
+                                            _ => {
+                                                let _ = match _serde::de::MapAccess::next_value::<
+                                                    _serde::de::IgnoredAny,
+                                                >(
+                                                    &mut __map
+                                                ) {
+                                                    _serde::export::Ok(__val) => __val,
+                                                    _serde::export::Err(__err) => {
+                                                        return _serde::export::Err(__err);
+                                                    }
+                                                };
+                                            }
+                                        }
+                                    }
+                                    let __field0 = match __field0 {
+                                        _serde::export::Some(__field0) => __field0,
+                                        _serde::export::None => {
+                                            match _serde::private::de::missing_field("a") {
+                                                _serde::export::Ok(__val) => __val,
+                                                _serde::export::Err(__err) => {
+                                                    return _serde::export::Err(__err);
+                                                }
+                                            }
+                                        }
+                                    };
+                                    _serde::export::Ok(Lifetimes::NoLifetimeMap { a: __field0 })
+                                }
+                            }
+                            const FIELDS: &'static [&'static str] = &["a"];
+                            _serde::de::VariantAccess::struct_variant(
+                                __variant,
+                                FIELDS,
+                                __Visitor {
+                                    marker: _serde::export::PhantomData::<Lifetimes<'a>>,
+                                    lifetime: _serde::export::PhantomData,
+                                },
+                            )
+                        }
+                    }
+                }
+            }
+            const VARIANTS: &'static [&'static str] = &[
+                "LifetimeSeq",
+                "NoLifetimeSeq",
+                "LifetimeMap",
+                "NoLifetimeMap",
+            ];
+            _serde::Deserializer::deserialize_enum(
+                __deserializer,
+                "Lifetimes",
+                VARIANTS,
+                __Visitor {
+                    marker: _serde::export::PhantomData::<Lifetimes<'a>>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};

test_suite/tests/expand/lifetimes.rs

@@ -0,0 +1,9 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+enum Lifetimes<'a> {
+    LifetimeSeq(&'a i32),
+    NoLifetimeSeq(i32),
+    LifetimeMap { a: &'a i32 },
+    NoLifetimeMap { a: i32 },
+}

test_suite/tests/expand/named_map.expanded.rs

@@ -0,0 +1,615 @@
+use serde::{Deserialize, Serialize};
+struct SerNamedMap<'a, 'b, A: 'a, B: 'b, C> {
+    a: &'a A,
+    b: &'b mut B,
+    c: C,
+}
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_SerNamedMap: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'a, 'b, A: 'a, B: 'b, C> _serde::Serialize for SerNamedMap<'a, 'b, A, B, C>
+    where
+        A: _serde::Serialize,
+        B: _serde::Serialize,
+        C: _serde::Serialize,
+    {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            let mut __serde_state = match _serde::Serializer::serialize_struct(
+                __serializer,
+                "SerNamedMap",
+                false as usize + 1 + 1 + 1,
+            ) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            match _serde::ser::SerializeStruct::serialize_field(&mut __serde_state, "a", &self.a) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            match _serde::ser::SerializeStruct::serialize_field(&mut __serde_state, "b", &self.b) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            match _serde::ser::SerializeStruct::serialize_field(&mut __serde_state, "c", &self.c) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            _serde::ser::SerializeStruct::end(__serde_state)
+        }
+    }
+};
+struct DeNamedMap<A, B, C> {
+    a: A,
+    b: B,
+    c: C,
+}
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_DeNamedMap: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de, A, B, C> _serde::Deserialize<'de> for DeNamedMap<A, B, C>
+    where
+        A: _serde::Deserialize<'de>,
+        B: _serde::Deserialize<'de>,
+        C: _serde::Deserialize<'de>,
+    {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {
+                __field0,
+                __field1,
+                __field2,
+                __ignore,
+            }
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "field identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        0u64 => _serde::export::Ok(__Field::__field0),
+                        1u64 => _serde::export::Ok(__Field::__field1),
+                        2u64 => _serde::export::Ok(__Field::__field2),
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"field index 0 <= i < 3",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        "a" => _serde::export::Ok(__Field::__field0),
+                        "b" => _serde::export::Ok(__Field::__field1),
+                        "c" => _serde::export::Ok(__Field::__field2),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        b"a" => _serde::export::Ok(__Field::__field0),
+                        b"b" => _serde::export::Ok(__Field::__field1),
+                        b"c" => _serde::export::Ok(__Field::__field2),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de, A, B, C>
+            where
+                A: _serde::Deserialize<'de>,
+                B: _serde::Deserialize<'de>,
+                C: _serde::Deserialize<'de>,
+            {
+                marker: _serde::export::PhantomData<DeNamedMap<A, B, C>>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, A, B, C> _serde::de::Visitor<'de> for __Visitor<'de, A, B, C>
+            where
+                A: _serde::Deserialize<'de>,
+                B: _serde::Deserialize<'de>,
+                C: _serde::Deserialize<'de>,
+            {
+                type Value = DeNamedMap<A, B, C>;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "struct DeNamedMap")
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    let __field0 = match match _serde::de::SeqAccess::next_element::<A>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                0usize,
+                                &"struct DeNamedMap with 3 elements",
+                            ));
+                        }
+                    };
+                    let __field1 = match match _serde::de::SeqAccess::next_element::<B>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                1usize,
+                                &"struct DeNamedMap with 3 elements",
+                            ));
+                        }
+                    };
+                    let __field2 = match match _serde::de::SeqAccess::next_element::<C>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                2usize,
+                                &"struct DeNamedMap with 3 elements",
+                            ));
+                        }
+                    };
+                    _serde::export::Ok(DeNamedMap {
+                        a: __field0,
+                        b: __field1,
+                        c: __field2,
+                    })
+                }
+                #[inline]
+                fn visit_map<__A>(
+                    self,
+                    mut __map: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::MapAccess<'de>,
+                {
+                    let mut __field0: _serde::export::Option<A> = _serde::export::None;
+                    let mut __field1: _serde::export::Option<B> = _serde::export::None;
+                    let mut __field2: _serde::export::Option<C> = _serde::export::None;
+                    while let _serde::export::Some(__key) =
+                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map) {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        }
+                    {
+                        match __key {
+                            __Field::__field0 => {
+                                if _serde::export::Option::is_some(&__field0) {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field("a"),
+                                    );
+                                }
+                                __field0 = _serde::export::Some(
+                                    match _serde::de::MapAccess::next_value::<A>(&mut __map) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    },
+                                );
+                            }
+                            __Field::__field1 => {
+                                if _serde::export::Option::is_some(&__field1) {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field("b"),
+                                    );
+                                }
+                                __field1 = _serde::export::Some(
+                                    match _serde::de::MapAccess::next_value::<B>(&mut __map) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    },
+                                );
+                            }
+                            __Field::__field2 => {
+                                if _serde::export::Option::is_some(&__field2) {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field("c"),
+                                    );
+                                }
+                                __field2 = _serde::export::Some(
+                                    match _serde::de::MapAccess::next_value::<C>(&mut __map) {
+                                        _serde::export::Ok(__val) => __val,
+                                        _serde::export::Err(__err) => {
+                                            return _serde::export::Err(__err);
+                                        }
+                                    },
+                                );
+                            }
+                            _ => {
+                                let _ = match _serde::de::MapAccess::next_value::<
+                                    _serde::de::IgnoredAny,
+                                >(&mut __map)
+                                {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                            }
+                        }
+                    }
+                    let __field0 = match __field0 {
+                        _serde::export::Some(__field0) => __field0,
+                        _serde::export::None => match _serde::private::de::missing_field("a") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        },
+                    };
+                    let __field1 = match __field1 {
+                        _serde::export::Some(__field1) => __field1,
+                        _serde::export::None => match _serde::private::de::missing_field("b") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        },
+                    };
+                    let __field2 = match __field2 {
+                        _serde::export::Some(__field2) => __field2,
+                        _serde::export::None => match _serde::private::de::missing_field("c") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        },
+                    };
+                    _serde::export::Ok(DeNamedMap {
+                        a: __field0,
+                        b: __field1,
+                        c: __field2,
+                    })
+                }
+            }
+            const FIELDS: &'static [&'static str] = &["a", "b", "c"];
+            _serde::Deserializer::deserialize_struct(
+                __deserializer,
+                "DeNamedMap",
+                FIELDS,
+                __Visitor {
+                    marker: _serde::export::PhantomData::<DeNamedMap<A, B, C>>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+        fn deserialize_in_place<__D>(
+            __deserializer: __D,
+            __place: &mut Self,
+        ) -> _serde::export::Result<(), __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {
+                __field0,
+                __field1,
+                __field2,
+                __ignore,
+            }
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "field identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        0u64 => _serde::export::Ok(__Field::__field0),
+                        1u64 => _serde::export::Ok(__Field::__field1),
+                        2u64 => _serde::export::Ok(__Field::__field2),
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"field index 0 <= i < 3",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        "a" => _serde::export::Ok(__Field::__field0),
+                        "b" => _serde::export::Ok(__Field::__field1),
+                        "c" => _serde::export::Ok(__Field::__field2),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        b"a" => _serde::export::Ok(__Field::__field0),
+                        b"b" => _serde::export::Ok(__Field::__field1),
+                        b"c" => _serde::export::Ok(__Field::__field2),
+                        _ => _serde::export::Ok(__Field::__ignore),
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de, 'place, A: 'place, B: 'place, C: 'place>
+            where
+                A: _serde::Deserialize<'de>,
+                B: _serde::Deserialize<'de>,
+                C: _serde::Deserialize<'de>,
+            {
+                place: &'place mut DeNamedMap<A, B, C>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, 'place, A: 'place, B: 'place, C: 'place> _serde::de::Visitor<'de>
+                for __Visitor<'de, 'place, A, B, C>
+            where
+                A: _serde::Deserialize<'de>,
+                B: _serde::Deserialize<'de>,
+                C: _serde::Deserialize<'de>,
+            {
+                type Value = ();
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "struct DeNamedMap")
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.a),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            0usize,
+                            &"struct DeNamedMap with 3 elements",
+                        ));
+                    }
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.b),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            1usize,
+                            &"struct DeNamedMap with 3 elements",
+                        ));
+                    }
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.c),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            2usize,
+                            &"struct DeNamedMap with 3 elements",
+                        ));
+                    }
+                    _serde::export::Ok(())
+                }
+                #[inline]
+                fn visit_map<__A>(
+                    self,
+                    mut __map: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::MapAccess<'de>,
+                {
+                    let mut __field0: bool = false;
+                    let mut __field1: bool = false;
+                    let mut __field2: bool = false;
+                    while let _serde::export::Some(__key) =
+                        match _serde::de::MapAccess::next_key::<__Field>(&mut __map) {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        }
+                    {
+                        match __key {
+                            __Field::__field0 => {
+                                if __field0 {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field("a"),
+                                    );
+                                }
+                                match _serde::de::MapAccess::next_value_seed(
+                                    &mut __map,
+                                    _serde::private::de::InPlaceSeed(&mut self.place.a),
+                                ) {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                                __field0 = true;
+                            }
+                            __Field::__field1 => {
+                                if __field1 {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field("b"),
+                                    );
+                                }
+                                match _serde::de::MapAccess::next_value_seed(
+                                    &mut __map,
+                                    _serde::private::de::InPlaceSeed(&mut self.place.b),
+                                ) {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                                __field1 = true;
+                            }
+                            __Field::__field2 => {
+                                if __field2 {
+                                    return _serde::export::Err(
+                                        <__A::Error as _serde::de::Error>::duplicate_field("c"),
+                                    );
+                                }
+                                match _serde::de::MapAccess::next_value_seed(
+                                    &mut __map,
+                                    _serde::private::de::InPlaceSeed(&mut self.place.c),
+                                ) {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                                __field2 = true;
+                            }
+                            _ => {
+                                let _ = match _serde::de::MapAccess::next_value::<
+                                    _serde::de::IgnoredAny,
+                                >(&mut __map)
+                                {
+                                    _serde::export::Ok(__val) => __val,
+                                    _serde::export::Err(__err) => {
+                                        return _serde::export::Err(__err);
+                                    }
+                                };
+                            }
+                        }
+                    }
+                    if !__field0 {
+                        self.place.a = match _serde::private::de::missing_field("a") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        };
+                    };
+                    if !__field1 {
+                        self.place.b = match _serde::private::de::missing_field("b") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        };
+                    };
+                    if !__field2 {
+                        self.place.c = match _serde::private::de::missing_field("c") {
+                            _serde::export::Ok(__val) => __val,
+                            _serde::export::Err(__err) => {
+                                return _serde::export::Err(__err);
+                            }
+                        };
+                    };
+                    _serde::export::Ok(())
+                }
+            }
+            const FIELDS: &'static [&'static str] = &["a", "b", "c"];
+            _serde::Deserializer::deserialize_struct(
+                __deserializer,
+                "DeNamedMap",
+                FIELDS,
+                __Visitor {
+                    place: __place,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};

test_suite/tests/expand/named_map.rs

@@ -0,0 +1,15 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize)]
+struct SerNamedMap<'a, 'b, A: 'a, B: 'b, C> {
+    a: &'a A,
+    b: &'b mut B,
+    c: C,
+}
+
+#[derive(Deserialize)]
+struct DeNamedMap<A, B, C> {
+    a: A,
+    b: B,
+    c: C,
+}

test_suite/tests/expand/named_tuple.expanded.rs

@@ -0,0 +1,250 @@
+use serde::{Deserialize, Serialize};
+struct SerNamedTuple<'a, 'b, A: 'a, B: 'b, C>(&'a A, &'b mut B, C);
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_SerNamedTuple: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'a, 'b, A: 'a, B: 'b, C> _serde::Serialize for SerNamedTuple<'a, 'b, A, B, C>
+    where
+        A: _serde::Serialize,
+        B: _serde::Serialize,
+        C: _serde::Serialize,
+    {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            let mut __serde_state = match _serde::Serializer::serialize_tuple_struct(
+                __serializer,
+                "SerNamedTuple",
+                0 + 1 + 1 + 1,
+            ) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            match _serde::ser::SerializeTupleStruct::serialize_field(&mut __serde_state, &self.0) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            match _serde::ser::SerializeTupleStruct::serialize_field(&mut __serde_state, &self.1) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            match _serde::ser::SerializeTupleStruct::serialize_field(&mut __serde_state, &self.2) {
+                _serde::export::Ok(__val) => __val,
+                _serde::export::Err(__err) => {
+                    return _serde::export::Err(__err);
+                }
+            };
+            _serde::ser::SerializeTupleStruct::end(__serde_state)
+        }
+    }
+};
+struct DeNamedTuple<A, B, C>(A, B, C);
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_DeNamedTuple: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de, A, B, C> _serde::Deserialize<'de> for DeNamedTuple<A, B, C>
+    where
+        A: _serde::Deserialize<'de>,
+        B: _serde::Deserialize<'de>,
+        C: _serde::Deserialize<'de>,
+    {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            struct __Visitor<'de, A, B, C>
+            where
+                A: _serde::Deserialize<'de>,
+                B: _serde::Deserialize<'de>,
+                C: _serde::Deserialize<'de>,
+            {
+                marker: _serde::export::PhantomData<DeNamedTuple<A, B, C>>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, A, B, C> _serde::de::Visitor<'de> for __Visitor<'de, A, B, C>
+            where
+                A: _serde::Deserialize<'de>,
+                B: _serde::Deserialize<'de>,
+                C: _serde::Deserialize<'de>,
+            {
+                type Value = DeNamedTuple<A, B, C>;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "tuple struct DeNamedTuple")
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    let __field0 = match match _serde::de::SeqAccess::next_element::<A>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                0usize,
+                                &"tuple struct DeNamedTuple with 3 elements",
+                            ));
+                        }
+                    };
+                    let __field1 = match match _serde::de::SeqAccess::next_element::<B>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                1usize,
+                                &"tuple struct DeNamedTuple with 3 elements",
+                            ));
+                        }
+                    };
+                    let __field2 = match match _serde::de::SeqAccess::next_element::<C>(&mut __seq)
+                    {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        _serde::export::Some(__value) => __value,
+                        _serde::export::None => {
+                            return _serde::export::Err(_serde::de::Error::invalid_length(
+                                2usize,
+                                &"tuple struct DeNamedTuple with 3 elements",
+                            ));
+                        }
+                    };
+                    _serde::export::Ok(DeNamedTuple(__field0, __field1, __field2))
+                }
+            }
+            _serde::Deserializer::deserialize_tuple_struct(
+                __deserializer,
+                "DeNamedTuple",
+                3usize,
+                __Visitor {
+                    marker: _serde::export::PhantomData::<DeNamedTuple<A, B, C>>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+        fn deserialize_in_place<__D>(
+            __deserializer: __D,
+            __place: &mut Self,
+        ) -> _serde::export::Result<(), __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            struct __Visitor<'de, 'place, A: 'place, B: 'place, C: 'place>
+            where
+                A: _serde::Deserialize<'de>,
+                B: _serde::Deserialize<'de>,
+                C: _serde::Deserialize<'de>,
+            {
+                place: &'place mut DeNamedTuple<A, B, C>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de, 'place, A: 'place, B: 'place, C: 'place> _serde::de::Visitor<'de>
+                for __Visitor<'de, 'place, A, B, C>
+            where
+                A: _serde::Deserialize<'de>,
+                B: _serde::Deserialize<'de>,
+                C: _serde::Deserialize<'de>,
+            {
+                type Value = ();
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "tuple struct DeNamedTuple")
+                }
+                #[inline]
+                fn visit_seq<__A>(
+                    self,
+                    mut __seq: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::SeqAccess<'de>,
+                {
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.0),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            0usize,
+                            &"tuple struct DeNamedTuple with 3 elements",
+                        ));
+                    }
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.1),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            1usize,
+                            &"tuple struct DeNamedTuple with 3 elements",
+                        ));
+                    }
+                    if let _serde::export::None = match _serde::de::SeqAccess::next_element_seed(
+                        &mut __seq,
+                        _serde::private::de::InPlaceSeed(&mut self.place.2),
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    } {
+                        return _serde::export::Err(_serde::de::Error::invalid_length(
+                            2usize,
+                            &"tuple struct DeNamedTuple with 3 elements",
+                        ));
+                    }
+                    _serde::export::Ok(())
+                }
+            }
+            _serde::Deserializer::deserialize_tuple_struct(
+                __deserializer,
+                "DeNamedTuple",
+                3usize,
+                __Visitor {
+                    place: __place,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};

test_suite/tests/expand/named_tuple.rs

@@ -0,0 +1,7 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize)]
+struct SerNamedTuple<'a, 'b, A: 'a, B: 'b, C>(&'a A, &'b mut B, C);
+
+#[derive(Deserialize)]
+struct DeNamedTuple<A, B, C>(A, B, C);

test_suite/tests/expand/named_unit.expanded.rs

@@ -0,0 +1,49 @@
+use serde::{Deserialize, Serialize};
+struct NamedUnit;
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_NamedUnit: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl _serde::Serialize for NamedUnit {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            _serde::Serializer::serialize_unit_struct(__serializer, "NamedUnit")
+        }
+    }
+};
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_NamedUnit: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de> _serde::Deserialize<'de> for NamedUnit {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            struct __Visitor;
+            impl<'de> _serde::de::Visitor<'de> for __Visitor {
+                type Value = NamedUnit;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "unit struct NamedUnit")
+                }
+                #[inline]
+                fn visit_unit<__E>(self) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    _serde::export::Ok(NamedUnit)
+                }
+            }
+            _serde::Deserializer::deserialize_unit_struct(__deserializer, "NamedUnit", __Visitor)
+        }
+    }
+};

test_suite/tests/expand/named_unit.rs

@@ -0,0 +1,4 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+struct NamedUnit;

test_suite/tests/expand/ser_enum.expanded.rs

@@ -0,0 +1,268 @@
+use serde::Serialize;
+enum SerEnum<'a, B: 'a, C: 'a, D>
+where
+    D: 'a,
+{
+    Unit,
+    Seq(i8, B, &'a C, &'a mut D),
+    Map { a: i8, b: B, c: &'a C, d: &'a mut D },
+    _Unit2,
+    _Seq2(i8, B, &'a C, &'a mut D),
+    _Map2 { a: i8, b: B, c: &'a C, d: &'a mut D },
+}
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_SerEnum: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'a, B: 'a, C: 'a, D> _serde::Serialize for SerEnum<'a, B, C, D>
+    where
+        D: 'a,
+        B: _serde::Serialize,
+        C: _serde::Serialize,
+        D: _serde::Serialize,
+    {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            match *self {
+                SerEnum::Unit => _serde::Serializer::serialize_unit_variant(
+                    __serializer,
+                    "SerEnum",
+                    0u32,
+                    "Unit",
+                ),
+                SerEnum::Seq(ref __field0, ref __field1, ref __field2, ref __field3) => {
+                    let mut __serde_state = match _serde::Serializer::serialize_tuple_variant(
+                        __serializer,
+                        "SerEnum",
+                        1u32,
+                        "Seq",
+                        0 + 1 + 1 + 1 + 1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field0,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field2,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field3,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::ser::SerializeTupleVariant::end(__serde_state)
+                }
+                SerEnum::Map {
+                    ref a,
+                    ref b,
+                    ref c,
+                    ref d,
+                } => {
+                    let mut __serde_state = match _serde::Serializer::serialize_struct_variant(
+                        __serializer,
+                        "SerEnum",
+                        2u32,
+                        "Map",
+                        0 + 1 + 1 + 1 + 1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "a",
+                        a,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "b",
+                        b,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "c",
+                        c,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "d",
+                        d,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::ser::SerializeStructVariant::end(__serde_state)
+                }
+                SerEnum::_Unit2 => _serde::Serializer::serialize_unit_variant(
+                    __serializer,
+                    "SerEnum",
+                    3u32,
+                    "_Unit2",
+                ),
+                SerEnum::_Seq2(ref __field0, ref __field1, ref __field2, ref __field3) => {
+                    let mut __serde_state = match _serde::Serializer::serialize_tuple_variant(
+                        __serializer,
+                        "SerEnum",
+                        4u32,
+                        "_Seq2",
+                        0 + 1 + 1 + 1 + 1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field0,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field2,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeTupleVariant::serialize_field(
+                        &mut __serde_state,
+                        __field3,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::ser::SerializeTupleVariant::end(__serde_state)
+                }
+                SerEnum::_Map2 {
+                    ref a,
+                    ref b,
+                    ref c,
+                    ref d,
+                } => {
+                    let mut __serde_state = match _serde::Serializer::serialize_struct_variant(
+                        __serializer,
+                        "SerEnum",
+                        5u32,
+                        "_Map2",
+                        0 + 1 + 1 + 1 + 1,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "a",
+                        a,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "b",
+                        b,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "c",
+                        c,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    match _serde::ser::SerializeStructVariant::serialize_field(
+                        &mut __serde_state,
+                        "d",
+                        d,
+                    ) {
+                        _serde::export::Ok(__val) => __val,
+                        _serde::export::Err(__err) => {
+                            return _serde::export::Err(__err);
+                        }
+                    };
+                    _serde::ser::SerializeStructVariant::end(__serde_state)
+                }
+            }
+        }
+    }
+};

test_suite/tests/expand/ser_enum.rs

@@ -0,0 +1,16 @@
+use serde::Serialize;
+
+#[derive(Serialize)]
+enum SerEnum<'a, B: 'a, C: 'a, D>
+where
+    D: 'a,
+{
+    Unit,
+    Seq(i8, B, &'a C, &'a mut D),
+    Map { a: i8, b: B, c: &'a C, d: &'a mut D },
+
+    // Make sure we can support more than one variant.
+    _Unit2,
+    _Seq2(i8, B, &'a C, &'a mut D),
+    _Map2 { a: i8, b: B, c: &'a C, d: &'a mut D },
+}

test_suite/tests/expand/void.expanded.rs

@@ -0,0 +1,124 @@
+use serde::{Deserialize, Serialize};
+enum Void {}
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_SERIALIZE_FOR_Void: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl _serde::Serialize for Void {
+        fn serialize<__S>(&self, __serializer: __S) -> _serde::export::Result<__S::Ok, __S::Error>
+        where
+            __S: _serde::Serializer,
+        {
+            match *self {}
+        }
+    }
+};
+#[doc(hidden)]
+#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+const _IMPL_DESERIALIZE_FOR_Void: () = {
+    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    extern crate serde as _serde;
+    #[automatically_derived]
+    impl<'de> _serde::Deserialize<'de> for Void {
+        fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+        where
+            __D: _serde::Deserializer<'de>,
+        {
+            #[allow(non_camel_case_types)]
+            enum __Field {}
+            struct __FieldVisitor;
+            impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+                type Value = __Field;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "variant identifier")
+                }
+                fn visit_u64<__E>(self, __value: u64) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        _ => _serde::export::Err(_serde::de::Error::invalid_value(
+                            _serde::de::Unexpected::Unsigned(__value),
+                            &"variant index 0 <= i < 0",
+                        )),
+                    }
+                }
+                fn visit_str<__E>(self, __value: &str) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        _ => _serde::export::Err(_serde::de::Error::unknown_variant(
+                            __value, VARIANTS,
+                        )),
+                    }
+                }
+                fn visit_bytes<__E>(
+                    self,
+                    __value: &[u8],
+                ) -> _serde::export::Result<Self::Value, __E>
+                where
+                    __E: _serde::de::Error,
+                {
+                    match __value {
+                        _ => {
+                            let __value = &_serde::export::from_utf8_lossy(__value);
+                            _serde::export::Err(_serde::de::Error::unknown_variant(
+                                __value, VARIANTS,
+                            ))
+                        }
+                    }
+                }
+            }
+            impl<'de> _serde::Deserialize<'de> for __Field {
+                #[inline]
+                fn deserialize<__D>(__deserializer: __D) -> _serde::export::Result<Self, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+                }
+            }
+            struct __Visitor<'de> {
+                marker: _serde::export::PhantomData<Void>,
+                lifetime: _serde::export::PhantomData<&'de ()>,
+            }
+            impl<'de> _serde::de::Visitor<'de> for __Visitor<'de> {
+                type Value = Void;
+                fn expecting(
+                    &self,
+                    __formatter: &mut _serde::export::Formatter,
+                ) -> _serde::export::fmt::Result {
+                    _serde::export::Formatter::write_str(__formatter, "enum Void")
+                }
+                fn visit_enum<__A>(
+                    self,
+                    __data: __A,
+                ) -> _serde::export::Result<Self::Value, __A::Error>
+                where
+                    __A: _serde::de::EnumAccess<'de>,
+                {
+                    _serde::export::Result::map(
+                        _serde::de::EnumAccess::variant::<__Field>(__data),
+                        |(__impossible, _)| match __impossible {},
+                    )
+                }
+            }
+            const VARIANTS: &'static [&'static str] = &[];
+            _serde::Deserializer::deserialize_enum(
+                __deserializer,
+                "Void",
+                VARIANTS,
+                __Visitor {
+                    marker: _serde::export::PhantomData::<Void>,
+                    lifetime: _serde::export::PhantomData,
+                },
+            )
+        }
+    }
+};

test_suite/tests/expand/void.rs

@@ -0,0 +1,4 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+enum Void {}

test_suite/tests/expandtest.rs

@@ -0,0 +1,7 @@
+#[cfg_attr(target_os = "emscripten", ignore)]
+#[cfg_attr(not(expandtest), ignore)]
+#[rustversion::attr(not(nightly), ignore)]
+#[test]
+fn expandtest() {
+    macrotest::expand("tests/expand/*.rs");
+}

test_suite/tests/test_de.rs

@@ -1,4 +1,5 @@
 #![allow(clippy::decimal_literal_representation, clippy::unreadable_literal)]
+#![cfg_attr(feature = "unstable", feature(never_type))]
 
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::default::Default;

test_suite/tests/test_gen.rs

@@ -265,7 +265,7 @@ fn test_gen() {
     #[cfg(feature = "unstable")]
     #[derive(Serialize, Deserialize)]
     struct NonAsciiIdents {
-        σ:  f64,
+        σ: f64,
     }
 
     #[derive(Serialize, Deserialize)]
@@ -691,6 +691,16 @@ fn test_gen() {
         #[serde(flatten, skip_deserializing)]
         flat: T,
     }
+
+    // https://github.com/serde-rs/serde/issues/1804
+    #[derive(Serialize, Deserialize)]
+    enum Message {
+        #[serde(skip)]
+        #[allow(dead_code)]
+        String(String),
+        #[serde(other)]
+        Unknown,
+    }
 }
 
 //////////////////////////////////////////////////////////////////////////

test_suite/tests/test_macros.rs

@@ -1145,6 +1145,20 @@ fn test_adjacently_tagged_enum() {
         ],
     );
 
+    // optional newtype with no content field
+    assert_de_tokens(
+        &AdjacentlyTagged::Newtype::<Option<u8>>(None),
+        &[
+            Token::Struct {
+                name: "AdjacentlyTagged",
+                len: 1,
+            },
+            Token::Str("t"),
+            Token::Str("Newtype"),
+            Token::StructEnd,
+        ],
+    );
+
     // tuple with tag first
     assert_tokens(
         &AdjacentlyTagged::Tuple::<u8>(1, 1),

test_suite/tests/test_ser.rs

@@ -1,4 +1,5 @@
 #![allow(clippy::unreadable_literal)]
+#![cfg_attr(feature = "unstable", feature(never_type))]
 
 use std::cell::RefCell;
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};

test_suite/tests/ui/remote/missing_field.stderr

@@ -3,5 +3,3 @@ error[E0063]: missing field `b` in initializer of `remote::S`
    |
 11 | #[serde(remote = "remote::S")]
    |                  ^^^^^^^^^^^ missing `b`
-
-For more information about this error, try `rustc --explain E0063`.

test_suite/tests/ui/remote/unknown_field.stderr

@@ -9,6 +9,3 @@ error[E0560]: struct `remote::S` has no field named `b`
    |
 12 |     b: u8,
    |     ^ help: a field with a similar name exists: `a`
-
-Some errors have detailed explanations: E0560, E0609.
-For more information about an error, try `rustc --explain E0560`.

test_suite/tests/ui/remote/wrong_de.stderr

@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 7 | #[derive(Deserialize)]
   |          ^^^^^^^^^^^
   |          |
-  |          expected u16, found u8
+  |          expected `u16`, found `u8`
   |          help: you can convert an `u8` to `u16`: `Deserialize.into()`
-
-For more information about this error, try `rustc --explain E0308`.
+  |
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

test_suite/tests/ui/remote/wrong_getter.stderr

@@ -2,7 +2,8 @@ error[E0308]: mismatched types
   --> $DIR/wrong_getter.rs:15:10
    |
 15 | #[derive(Serialize)]
-   |          ^^^^^^^^^ expected u8, found u16
+   |          ^^^^^^^^^ expected `u8`, found `u16`
    |
-   = note: expected type `&u8`
-              found type `&u16`
+   = note: expected reference `&u8`
+              found reference `&u16`
+   = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

test_suite/tests/ui/remote/wrong_ser.stderr

@@ -2,9 +2,8 @@ error[E0308]: mismatched types
  --> $DIR/wrong_ser.rs:9:10
   |
 9 | #[derive(Serialize)]
-  |          ^^^^^^^^^ expected u8, found u16
+  |          ^^^^^^^^^ expected `u8`, found `u16`
   |
-  = note: expected type `&u8`
-             found type `&u16`
-
-For more information about this error, try `rustc --explain E0308`.
+  = note: expected reference `&u8`
+             found reference `&u16`
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

test_suite/tests/ui/struct-representation/internally-tagged-unit.stderr

@@ -3,3 +3,5 @@ error: #[serde(tag = "...")] can only be used on enums and structs with named fi
   |
 3 | #[derive(Serialize)]
   |          ^^^^^^^^^
+  |
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)