Release 1.0.206

Resolve doc_markdown pedantic lint on regression test function
warning: you should put bare URLs between `<`/`>` or make a proper Markdown link --> test_suite/tests/test_annotations.rs:2383:25 | 2383 | /// Regression test for https://github.com/serde-rs/serde/issues/1904 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `<https://github.com/serde-rs/serde/issues/1904>` | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#doc_markdown = note: `-W clippy::doc-markdown` implied by `-W clippy::pedantic` = help: to override `-W clippy::pedantic` add `#[allow(clippy::doc_markdown)]`
2026-04-23 03:38:00 +00:00 · 2024-08-11 00:08:37 -07:00 · 2024-08-11 00:08:16 -07:00 · 2024-08-11 00:05:56 -07:00 · 2024-08-11 00:05:31 -07:00 · 2024-08-10 23:59:23 -07:00
34 changed files with 693 additions and 280 deletions
@@ -84,6 +84,7 @@ jobs:
      - uses: dtolnay/rust-toolchain@master
        with:
          toolchain: ${{matrix.rust}}
+      - run: sed -i '/"test_suite"/d' Cargo.toml
      - run: cd serde && cargo build --features rc
      - run: cd serde && cargo build --no-default-features
      - run: cd serde && cargo build
@@ -95,6 +96,7 @@ jobs:
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@1.56.0
+      - run: sed -i '/"test_suite"/d' Cargo.toml
      - run: cd serde && cargo check --no-default-features
      - run: cd serde && cargo check
      - run: cd serde_derive && cargo check
@@ -106,6 +108,7 @@ jobs:
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@1.36.0
+      - run: sed -i '/"test_suite"/d' Cargo.toml
      - run: cd serde && cargo build --no-default-features --features alloc

  minimal:
@@ -46,8 +46,8 @@ fn main() {
 Serde is one of the most widely used Rust libraries so any place that Rustaceans
 congregate will be able to help you out. For chat, consider trying the
 [#rust-questions] or [#rust-beginners] channels of the unofficial community
-Discord (invite: <https://discord.gg/rust-lang-community>, the [#rust-usage] or
-[#beginners] channels of the official Rust Project Discord (invite:
+Discord (invite: <https://discord.gg/rust-lang-community>), the [#rust-usage]
+or [#beginners] channels of the official Rust Project Discord (invite:
 <https://discord.gg/rust-lang>), or the [#general][zulip] stream in Zulip. For
 asynchronous, consider the [\[rust\] tag on StackOverflow][stackoverflow], the
 [/r/rust] subreddit which has a pinned weekly easy questions post, or the Rust
@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.201"
+version = "1.0.206"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 build = "build.rs"
 categories = ["encoding", "no-std", "no-std::no-alloc"]
@@ -29,7 +29,7 @@ features = ["derive", "rc"]
 [package.metadata.docs.rs]
 features = ["derive", "rc", "unstable"]
 targets = ["x86_64-unknown-linux-gnu"]
-rustdoc-args = ["--cfg", "doc_cfg", "--generate-link-to-definition"]
+rustdoc-args = ["--generate-link-to-definition"]

 # This cfg cannot be enabled, but it still forces Cargo to keep serde_derive's
 # version in lockstep with serde's, even if someone depends on the two crates
@@ -37,7 +37,7 @@ rustdoc-args = ["--cfg", "doc_cfg", "--generate-link-to-definition"]
 # is compatible with exactly one serde release because the generated code
 # involves nonpublic APIs which are not bound by semver.
 [target.'cfg(any())'.dependencies]
-serde_derive = { version = "=1.0.201", path = "../serde_derive" }
+serde_derive = { version = "=1.0.206", path = "../serde_derive" }


 ### FEATURES #################################################################
@@ -14,10 +14,10 @@ fn main() {
    };

    if minor >= 77 {
-        println!("cargo:rustc-check-cfg=cfg(doc_cfg)");
        println!("cargo:rustc-check-cfg=cfg(no_core_cstr)");
        println!("cargo:rustc-check-cfg=cfg(no_core_num_saturating)");
        println!("cargo:rustc-check-cfg=cfg(no_core_try_from)");
+        println!("cargo:rustc-check-cfg=cfg(no_diagnostic_namespace)");
        println!("cargo:rustc-check-cfg=cfg(no_float_copysign)");
        println!("cargo:rustc-check-cfg=cfg(no_num_nonzero_signed)");
        println!("cargo:rustc-check-cfg=cfg(no_relaxed_trait_bounds)");
@@ -85,6 +85,12 @@ fn main() {
    if minor < 74 {
        println!("cargo:rustc-cfg=no_core_num_saturating");
    }
+
+    // Support for the `#[diagnostic]` tool attribute namespace
+    // https://blog.rust-lang.org/2024/05/02/Rust-1.78.0.html#diagnostic-attributes
+    if minor < 78 {
+        println!("cargo:rustc-cfg=no_diagnostic_namespace");
+    }
 }

 fn rustc_minor_version() -> Option<u32> {
@@ -39,7 +39,7 @@ impl<'de> Deserialize<'de> for () {
 }

 #[cfg(feature = "unstable")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "unstable")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "unstable")))]
 impl<'de> Deserialize<'de> for ! {
    fn deserialize<D>(_deserializer: D) -> Result<Self, D::Error>
    where
@@ -695,7 +695,7 @@ impl<'a, 'de> Visitor<'de> for StringInPlaceVisitor<'a> {
 }

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de> Deserialize<'de> for String {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
@@ -839,7 +839,7 @@ impl<'de> Visitor<'de> for CStringVisitor {
 }

 #[cfg(any(feature = "std", all(not(no_core_cstr), feature = "alloc")))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de> Deserialize<'de> for CString {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
@@ -868,7 +868,7 @@ macro_rules! forwarded_impl {

 forwarded_impl! {
    #[cfg(any(feature = "std", all(not(no_core_cstr), feature = "alloc")))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    (), Box<CStr>, CString::into_boxed_c_str
 }

@@ -1086,7 +1086,7 @@ fn nop_reserve<T>(_seq: T, _n: usize) {}

 seq_impl!(
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    BinaryHeap<T: Ord>,
    seq,
    BinaryHeap::clear,
@@ -1097,7 +1097,7 @@ seq_impl!(

 seq_impl!(
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    BTreeSet<T: Eq + Ord>,
    seq,
    BTreeSet::clear,
@@ -1108,7 +1108,7 @@ seq_impl!(

 seq_impl!(
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    LinkedList<T>,
    seq,
    LinkedList::clear,
@@ -1119,7 +1119,7 @@ seq_impl!(

 seq_impl!(
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    HashSet<T: Eq + Hash, S: BuildHasher + Default>,
    seq,
    HashSet::clear,
@@ -1130,7 +1130,7 @@ seq_impl!(

 seq_impl!(
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    VecDeque<T>,
    seq,
    VecDeque::clear,
@@ -1142,7 +1142,7 @@ seq_impl!(
 ////////////////////////////////////////////////////////////////////////////////

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, T> Deserialize<'de> for Vec<T>
 where
    T: Deserialize<'de>,
@@ -1393,82 +1393,103 @@ array_impls! {
 macro_rules! tuple_impls {
    ($($len:tt => ($($n:tt $name:ident)+))+) => {
        $(
-            impl<'de, $($name: Deserialize<'de>),+> Deserialize<'de> for ($($name,)+) {
-                #[inline]
-                fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-                where
-                    D: Deserializer<'de>,
-                {
-                    struct TupleVisitor<$($name,)+> {
-                        marker: PhantomData<($($name,)+)>,
-                    }
-
-                    impl<'de, $($name: Deserialize<'de>),+> Visitor<'de> for TupleVisitor<$($name,)+> {
-                        type Value = ($($name,)+);
-
-                        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                            formatter.write_str(concat!("a tuple of size ", $len))
-                        }
-
-                        #[inline]
-                        #[allow(non_snake_case)]
-                        fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
-                        where
-                            A: SeqAccess<'de>,
-                        {
-                            $(
-                                let $name = match tri!(seq.next_element()) {
-                                    Some(value) => value,
-                                    None => return Err(Error::invalid_length($n, &self)),
-                                };
-                            )+
-
-                            Ok(($($name,)+))
-                        }
-                    }
-
-                    deserializer.deserialize_tuple($len, TupleVisitor { marker: PhantomData })
-                }
-
-                #[inline]
-                fn deserialize_in_place<D>(deserializer: D, place: &mut Self) -> Result<(), D::Error>
-                where
-                    D: Deserializer<'de>,
-                {
-                    struct TupleInPlaceVisitor<'a, $($name: 'a,)+>(&'a mut ($($name,)+));
-
-                    impl<'a, 'de, $($name: Deserialize<'de>),+> Visitor<'de> for TupleInPlaceVisitor<'a, $($name,)+> {
-                        type Value = ();
-
-                        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                            formatter.write_str(concat!("a tuple of size ", $len))
-                        }
-
-                        #[inline]
-                        #[allow(non_snake_case)]
-                        fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
-                        where
-                            A: SeqAccess<'de>,
-                        {
-                            $(
-                                if tri!(seq.next_element_seed(InPlaceSeed(&mut (self.0).$n))).is_none() {
-                                    return Err(Error::invalid_length($n, &self));
-                                }
-                            )+
-
-                            Ok(())
-                        }
-                    }
-
-                    deserializer.deserialize_tuple($len, TupleInPlaceVisitor(place))
-                }
+            #[cfg_attr(docsrs, doc(hidden))]
+            impl<'de, $($name),+> Deserialize<'de> for ($($name,)+)
+            where
+                $($name: Deserialize<'de>,)+
+            {
+                tuple_impl_body!($len => ($($n $name)+));
            }
        )+
-    }
+    };
+}
+
+macro_rules! tuple_impl_body {
+    ($len:tt => ($($n:tt $name:ident)+)) => {
+        #[inline]
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct TupleVisitor<$($name,)+> {
+                marker: PhantomData<($($name,)+)>,
+            }
+
+            impl<'de, $($name: Deserialize<'de>),+> Visitor<'de> for TupleVisitor<$($name,)+> {
+                type Value = ($($name,)+);
+
+                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                    formatter.write_str(concat!("a tuple of size ", $len))
+                }
+
+                #[inline]
+                #[allow(non_snake_case)]
+                fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+                where
+                    A: SeqAccess<'de>,
+                {
+                    $(
+                        let $name = match tri!(seq.next_element()) {
+                            Some(value) => value,
+                            None => return Err(Error::invalid_length($n, &self)),
+                        };
+                    )+
+
+                    Ok(($($name,)+))
+                }
+            }
+
+            deserializer.deserialize_tuple($len, TupleVisitor { marker: PhantomData })
+        }
+
+        #[inline]
+        fn deserialize_in_place<D>(deserializer: D, place: &mut Self) -> Result<(), D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct TupleInPlaceVisitor<'a, $($name: 'a,)+>(&'a mut ($($name,)+));
+
+            impl<'a, 'de, $($name: Deserialize<'de>),+> Visitor<'de> for TupleInPlaceVisitor<'a, $($name,)+> {
+                type Value = ();
+
+                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                    formatter.write_str(concat!("a tuple of size ", $len))
+                }
+
+                #[inline]
+                #[allow(non_snake_case)]
+                fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+                where
+                    A: SeqAccess<'de>,
+                {
+                    $(
+                        if tri!(seq.next_element_seed(InPlaceSeed(&mut (self.0).$n))).is_none() {
+                            return Err(Error::invalid_length($n, &self));
+                        }
+                    )+
+
+                    Ok(())
+                }
+            }
+
+            deserializer.deserialize_tuple($len, TupleInPlaceVisitor(place))
+        }
+    };
+}
+
+#[cfg_attr(docsrs, doc(fake_variadic))]
+#[cfg_attr(
+    docsrs,
+    doc = "This trait is implemented for tuples up to 16 items long."
+)]
+impl<'de, T> Deserialize<'de> for (T,)
+where
+    T: Deserialize<'de>,
+{
+    tuple_impl_body!(1 => (0 T));
 }

 tuple_impls! {
-    1  => (0 T0)
    2  => (0 T0 1 T1)
    3  => (0 T0 1 T1 2 T2)
    4  => (0 T0 1 T1 2 T2 3 T3)
@@ -1546,7 +1567,7 @@ macro_rules! map_impl {

 map_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    BTreeMap<K: Ord, V>,
    map,
    BTreeMap::new(),
@@ -1554,7 +1575,7 @@ map_impl! {

 map_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    HashMap<K: Eq + Hash, V, S: BuildHasher + Default>,
    map,
    HashMap::with_capacity_and_hasher(size_hint::cautious::<(K, V)>(map.size_hint()), S::default()),
@@ -1696,7 +1717,7 @@ macro_rules! deserialize_enum {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'de> Deserialize<'de> for net::IpAddr {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
@@ -1717,13 +1738,13 @@ impl<'de> Deserialize<'de> for net::IpAddr {

 parse_ip_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    net::Ipv4Addr, "IPv4 address", 4
 }

 parse_ip_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    net::Ipv6Addr, "IPv6 address", 16
 }

@@ -1750,7 +1771,7 @@ macro_rules! parse_socket_impl {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'de> Deserialize<'de> for net::SocketAddr {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
@@ -1771,14 +1792,14 @@ impl<'de> Deserialize<'de> for net::SocketAddr {

 parse_socket_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    net::SocketAddrV4, "IPv4 socket address",
    |(ip, port)| net::SocketAddrV4::new(ip, port),
 }

 parse_socket_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    net::SocketAddrV6, "IPv6 socket address",
    |(ip, port)| net::SocketAddrV6::new(ip, port, 0, 0),
 }
@@ -1814,7 +1835,7 @@ impl<'a> Visitor<'a> for PathVisitor {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'de: 'a, 'a> Deserialize<'de> for &'a Path {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
@@ -1869,7 +1890,7 @@ impl<'de> Visitor<'de> for PathBufVisitor {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'de> Deserialize<'de> for PathBuf {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
@@ -1881,7 +1902,7 @@ impl<'de> Deserialize<'de> for PathBuf {

 forwarded_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    (), Box<Path>, PathBuf::into_boxed_path
 }

@@ -1943,7 +1964,7 @@ impl<'de> Visitor<'de> for OsStringVisitor {
 }

 #[cfg(all(feature = "std", any(unix, windows)))]
-#[cfg_attr(doc_cfg, doc(cfg(all(feature = "std", any(unix, windows)))))]
+#[cfg_attr(docsrs, doc(cfg(all(feature = "std", any(unix, windows)))))]
 impl<'de> Deserialize<'de> for OsString {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
@@ -1957,30 +1978,30 @@ impl<'de> Deserialize<'de> for OsString {

 forwarded_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    (T), Box<T>, Box::new
 }

 forwarded_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    (T), Box<[T]>, Vec::into_boxed_slice
 }

 forwarded_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    (), Box<str>, String::into_boxed_str
 }

 forwarded_impl! {
    #[cfg(all(feature = "std", any(unix, windows)))]
-    #[cfg_attr(doc_cfg, doc(cfg(all(feature = "std", any(unix, windows)))))]
+    #[cfg_attr(docsrs, doc(cfg(all(feature = "std", any(unix, windows)))))]
    (), Box<OsStr>, OsString::into_boxed_os_str
 }

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, 'a, T> Deserialize<'de> for Cow<'a, T>
 where
    T: ?Sized + ToOwned,
@@ -2003,7 +2024,7 @@ where
 /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
 #[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 #[cfg_attr(
-    doc_cfg,
+    docsrs,
    doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc"))))
 )]
 impl<'de, T> Deserialize<'de> for RcWeak<T>
@@ -2025,7 +2046,7 @@ where
 /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
 #[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 #[cfg_attr(
-    doc_cfg,
+    docsrs,
    doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc"))))
 )]
 impl<'de, T> Deserialize<'de> for ArcWeak<T>
@@ -2073,7 +2094,7 @@ box_forwarded_impl! {
    ///
    /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
    #[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
-    #[cfg_attr(doc_cfg, doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))))]
+    #[cfg_attr(docsrs, doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))))]
    Rc
 }

@@ -2086,7 +2107,7 @@ box_forwarded_impl! {
    ///
    /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
    #[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
-    #[cfg_attr(doc_cfg, doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))))]
+    #[cfg_attr(docsrs, doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))))]
    Arc
 }

@@ -2110,13 +2131,13 @@ forwarded_impl! {

 forwarded_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    (T), Mutex<T>, Mutex::new
 }

 forwarded_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    (T), RwLock<T>, RwLock::new
 }

@@ -2271,7 +2292,7 @@ impl<'de> Deserialize<'de> for Duration {
 ////////////////////////////////////////////////////////////////////////////////

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'de> Deserialize<'de> for SystemTime {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
@@ -3107,7 +3128,7 @@ macro_rules! atomic_impl {
    ($($ty:ident $size:expr)*) => {
        $(
            #[cfg(any(no_target_has_atomic, target_has_atomic = $size))]
-            #[cfg_attr(doc_cfg, doc(cfg(all(feature = "std", target_has_atomic = $size))))]
+            #[cfg_attr(docsrs, doc(cfg(all(feature = "std", target_has_atomic = $size))))]
            impl<'de> Deserialize<'de> for $ty {
                fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
                where
@@ -532,6 +532,13 @@ impl<'a> Display for Expected + 'a {
 /// deserializer lifetimes] for a more detailed explanation of these lifetimes.
 ///
 /// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        note = "for local types consider adding `#[derive(serde::Deserialize)]` to your `{Self}` type",
+        note = "for types from other crates check whether the crate offers a `serde` feature flag",
+    )
+)]
 pub trait Deserialize<'de>: Sized {
    /// Deserialize this value from the given Serde deserializer.
    ///
@@ -1525,7 +1532,7 @@ pub trait Visitor<'de>: Sized {
    /// `String`.
    #[inline]
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
    where
        E: Error,
@@ -1584,7 +1591,7 @@ pub trait Visitor<'de>: Sized {
    /// The default implementation forwards to `visit_bytes` and then drops the
    /// `Vec<u8>`.
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
    where
        E: Error,
@@ -112,7 +112,7 @@ impl Debug for Error {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl error::Error for Error {
    fn description(&self) -> &str {
        &self.err
@@ -185,14 +185,14 @@ impl<E> Debug for UnitDeserializer<E> {

 /// A deserializer that cannot be instantiated.
 #[cfg(feature = "unstable")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "unstable")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "unstable")))]
 pub struct NeverDeserializer<E> {
    never: !,
    marker: PhantomData<E>,
 }

 #[cfg(feature = "unstable")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "unstable")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "unstable")))]
 impl<'de, E> IntoDeserializer<'de, E> for !
 where
    E: de::Error,
@@ -565,7 +565,7 @@ impl<'de, E> Debug for BorrowedStrDeserializer<'de, E> {

 /// A deserializer holding a `String`.
 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 pub struct StringDeserializer<E> {
    value: String,
    marker: PhantomData<E>,
@@ -582,7 +582,7 @@ impl<E> Clone for StringDeserializer<E> {
 }

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, E> IntoDeserializer<'de, E> for String
 where
    E: de::Error,
@@ -670,7 +670,7 @@ impl<E> Debug for StringDeserializer<E> {

 /// A deserializer holding a `Cow<str>`.
 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 pub struct CowStrDeserializer<'a, E> {
    value: Cow<'a, str>,
    marker: PhantomData<E>,
@@ -687,7 +687,7 @@ impl<'a, E> Clone for CowStrDeserializer<'a, E> {
 }

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, 'a, E> IntoDeserializer<'de, E> for Cow<'a, str>
 where
    E: de::Error,
@@ -1006,7 +1006,7 @@ where
 ////////////////////////////////////////////////////////////////////////////////

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, T, E> IntoDeserializer<'de, E> for Vec<T>
 where
    T: IntoDeserializer<'de, E>,
@@ -1020,7 +1020,7 @@ where
 }

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, T, E> IntoDeserializer<'de, E> for BTreeSet<T>
 where
    T: IntoDeserializer<'de, E> + Eq + Ord,
@@ -1034,7 +1034,7 @@ where
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'de, T, S, E> IntoDeserializer<'de, E> for HashSet<T, S>
 where
    T: IntoDeserializer<'de, E> + Eq + Hash,
@@ -1421,7 +1421,7 @@ impl Expected for ExpectedInMap {
 ////////////////////////////////////////////////////////////////////////////////

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, K, V, E> IntoDeserializer<'de, E> for BTreeMap<K, V>
 where
    K: IntoDeserializer<'de, E> + Eq + Ord,
@@ -1436,7 +1436,7 @@ where
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'de, K, V, S, E> IntoDeserializer<'de, E> for HashMap<K, V, S>
 where
    K: IntoDeserializer<'de, E> + Eq + Hash,
@@ -95,16 +95,17 @@
 ////////////////////////////////////////////////////////////////////////////////

 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.201")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.206")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Show which crate feature enables conditionally compiled APIs in documentation.
-#![cfg_attr(doc_cfg, feature(doc_cfg))]
+#![cfg_attr(docsrs, feature(doc_cfg, rustdoc_internals))]
+#![cfg_attr(docsrs, allow(internal_features))]
 // 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(error_in_core, never_type))]
+#![cfg_attr(feature = "unstable", feature(never_type))]
 #![allow(unknown_lints, bare_trait_objects, deprecated)]
 // Ignored clippy and clippy_pedantic lints
 #![allow(
@@ -330,7 +331,7 @@ extern crate serde_derive;

 /// Derive macro available if serde is built with `features = ["derive"]`.
 #[cfg(feature = "serde_derive")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "derive")))]
 pub use serde_derive::{Deserialize, Serialize};

 #[cfg(all(not(no_serde_derive), any(feature = "std", feature = "alloc")))]
@@ -1125,8 +1125,7 @@ where
    where
        T: ?Sized + Serialize,
    {
-        tri!(self.0.serialize_key(variant));
-        self.0.serialize_value(value)
+        self.0.serialize_entry(variant, value)
    }

    fn serialize_seq(self, _: Option<usize>) -> Result<Self::SerializeSeq, Self::Error> {
@@ -48,7 +48,7 @@ impl Serialize for str {
 }

 #[cfg(any(feature = "std", feature = "alloc"))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl Serialize for String {
    #[inline]
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -71,7 +71,7 @@ impl<'a> Serialize for fmt::Arguments<'a> {
 ////////////////////////////////////////////////////////////////////////////////

 #[cfg(any(feature = "std", not(no_core_cstr)))]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for CStr {
    #[inline]
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -83,7 +83,7 @@ impl Serialize for CStr {
 }

 #[cfg(any(feature = "std", all(not(no_core_cstr), feature = "alloc")))]
-#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl Serialize for CString {
    #[inline]
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -232,37 +232,37 @@ macro_rules! seq_impl {

 seq_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    BinaryHeap<T: Ord>
 }

 seq_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    BTreeSet<T: Ord>
 }

 seq_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    HashSet<T: Eq + Hash, H: BuildHasher>
 }

 seq_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    LinkedList<T>
 }

 seq_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    Vec<T>
 }

 seq_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    VecDeque<T>
 }

@@ -371,7 +371,7 @@ impl Serialize for () {
 }

 #[cfg(feature = "unstable")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "unstable")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "unstable")))]
 impl Serialize for ! {
    fn serialize<S>(&self, _serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -386,28 +386,46 @@ impl Serialize for ! {
 macro_rules! tuple_impls {
    ($($len:expr => ($($n:tt $name:ident)+))+) => {
        $(
+            #[cfg_attr(docsrs, doc(hidden))]
            impl<$($name),+> Serialize for ($($name,)+)
            where
                $($name: Serialize,)+
            {
-                #[inline]
-                fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-                where
-                    S: Serializer,
-                {
-                    let mut tuple = tri!(serializer.serialize_tuple($len));
-                    $(
-                        tri!(tuple.serialize_element(&self.$n));
-                    )+
-                    tuple.end()
-                }
+                tuple_impl_body!($len => ($($n)+));
            }
        )+
-    }
+    };
+}
+
+macro_rules! tuple_impl_body {
+    ($len:expr => ($($n:tt)+)) => {
+        #[inline]
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            let mut tuple = tri!(serializer.serialize_tuple($len));
+            $(
+                tri!(tuple.serialize_element(&self.$n));
+            )+
+            tuple.end()
+        }
+    };
+}
+
+#[cfg_attr(docsrs, doc(fake_variadic))]
+#[cfg_attr(
+    docsrs,
+    doc = "This trait is implemented for tuples up to 16 items long."
+)]
+impl<T> Serialize for (T,)
+where
+    T: Serialize,
+{
+    tuple_impl_body!(1 => (0));
 }

 tuple_impls! {
-    1 => (0 T0)
    2 => (0 T0 1 T1)
    3 => (0 T0 1 T1 2 T2)
    4 => (0 T0 1 T1 2 T2 3 T3)
@@ -476,13 +494,13 @@ macro_rules! map_impl {

 map_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    BTreeMap<K: Ord, V>
 }

 map_impl! {
    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
    HashMap<K: Eq + Hash, V, H: BuildHasher>
 }

@@ -516,7 +534,7 @@ deref_impl! {

 deref_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    <T> Serialize for Box<T> where T: ?Sized + Serialize
 }

@@ -530,7 +548,7 @@ deref_impl! {
    ///
    /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
    #[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
-    #[cfg_attr(doc_cfg, doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))))]
+    #[cfg_attr(docsrs, doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))))]
    <T> Serialize for Rc<T> where T: ?Sized + Serialize
 }

@@ -544,13 +562,13 @@ deref_impl! {
    ///
    /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
    #[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
-    #[cfg_attr(doc_cfg, doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))))]
+    #[cfg_attr(docsrs, doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))))]
    <T> Serialize for Arc<T> where T: ?Sized + Serialize
 }

 deref_impl! {
    #[cfg(any(feature = "std", feature = "alloc"))]
-    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
    <'a, T> Serialize for Cow<'a, T> where T: ?Sized + Serialize + ToOwned
 }

@@ -561,7 +579,7 @@ deref_impl! {
 /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
 #[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 #[cfg_attr(
-    doc_cfg,
+    docsrs,
    doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc"))))
 )]
 impl<T> Serialize for RcWeak<T>
@@ -581,7 +599,7 @@ where
 /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
 #[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 #[cfg_attr(
-    doc_cfg,
+    docsrs,
    doc(cfg(all(feature = "rc", any(feature = "std", feature = "alloc"))))
 )]
 impl<T> Serialize for ArcWeak<T>
@@ -660,7 +678,7 @@ where
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<T> Serialize for Mutex<T>
 where
    T: ?Sized + Serialize,
@@ -677,7 +695,7 @@ where
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<T> Serialize for RwLock<T>
 where
    T: ?Sized + Serialize,
@@ -731,7 +749,7 @@ impl Serialize for Duration {
 ////////////////////////////////////////////////////////////////////////////////

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for SystemTime {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -776,7 +794,7 @@ macro_rules! serialize_display_bounded_length {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for net::IpAddr {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -847,7 +865,7 @@ fn test_format_u8() {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for net::Ipv4Addr {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -872,7 +890,7 @@ impl Serialize for net::Ipv4Addr {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for net::Ipv6Addr {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -889,7 +907,7 @@ impl Serialize for net::Ipv6Addr {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for net::SocketAddr {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -914,7 +932,7 @@ impl Serialize for net::SocketAddr {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for net::SocketAddrV4 {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -931,7 +949,7 @@ impl Serialize for net::SocketAddrV4 {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for net::SocketAddrV6 {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -953,7 +971,7 @@ impl Serialize for net::SocketAddrV6 {
 ////////////////////////////////////////////////////////////////////////////////

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for Path {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -967,7 +985,7 @@ impl Serialize for Path {
 }

 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl Serialize for PathBuf {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -978,7 +996,7 @@ impl Serialize for PathBuf {
 }

 #[cfg(all(feature = "std", any(unix, windows)))]
-#[cfg_attr(doc_cfg, doc(cfg(all(feature = "std", any(unix, windows)))))]
+#[cfg_attr(docsrs, doc(cfg(all(feature = "std", any(unix, windows)))))]
 impl Serialize for OsStr {
    #[cfg(unix)]
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -1001,7 +1019,7 @@ impl Serialize for OsStr {
 }

 #[cfg(all(feature = "std", any(unix, windows)))]
-#[cfg_attr(doc_cfg, doc(cfg(all(feature = "std", any(unix, windows)))))]
+#[cfg_attr(docsrs, doc(cfg(all(feature = "std", any(unix, windows)))))]
 impl Serialize for OsString {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
@@ -1060,7 +1078,7 @@ macro_rules! atomic_impl {
    ($($ty:ident $size:expr)*) => {
        $(
            #[cfg(any(no_target_has_atomic, target_has_atomic = $size))]
-            #[cfg_attr(doc_cfg, doc(cfg(all(feature = "std", target_has_atomic = $size))))]
+            #[cfg_attr(docsrs, doc(cfg(all(feature = "std", target_has_atomic = $size))))]
            impl Serialize for $ty {
                fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
                where
@@ -215,6 +215,13 @@ declare_error_trait!(Error: Sized + Debug + Display);
 /// [`linked-hash-map`]: https://crates.io/crates/linked-hash-map
 /// [`serde_derive`]: https://crates.io/crates/serde_derive
 /// [derive section of the manual]: https://serde.rs/derive.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        note = "for local types consider adding `#[derive(serde::Serialize)]` to your `{Self}` type",
+        note = "for types from other crates check whether the crate offers a `serde` feature flag",
+    )
+)]
 pub trait Serialize {
    /// Serialize this value into the given Serde serializer.
    ///
@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.201"
+version = "1.0.206"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 categories = ["no-std", "no-std::no-alloc"]
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -1,6 +1,7 @@
 fn main() {
    // Warning: build.rs is not published to crates.io.

+    println!("cargo:rerun-if-changed=build.rs");
    println!("cargo:rustc-cfg=check_cfg");
    println!("cargo:rustc-check-cfg=cfg(check_cfg)");
    println!("cargo:rustc-check-cfg=cfg(exhaustive)");
@@ -281,11 +281,21 @@ fn deserialize_body(cont: &Container, params: &Parameters) -> Fragment {
    } else if let attr::Identifier::No = cont.attrs.identifier() {
        match &cont.data {
            Data::Enum(variants) => deserialize_enum(params, variants, &cont.attrs),
-            Data::Struct(Style::Struct, fields) => {
-                deserialize_struct(params, fields, &cont.attrs, StructForm::Struct)
-            }
+            Data::Struct(Style::Struct, fields) => deserialize_struct(
+                params,
+                fields,
+                &cont.attrs,
+                cont.attrs.has_flatten(),
+                StructForm::Struct,
+            ),
            Data::Struct(Style::Tuple, fields) | Data::Struct(Style::Newtype, fields) => {
-                deserialize_tuple(params, fields, &cont.attrs, TupleForm::Tuple)
+                deserialize_tuple(
+                    params,
+                    fields,
+                    &cont.attrs,
+                    cont.attrs.has_flatten(),
+                    TupleForm::Tuple,
+                )
            }
            Data::Struct(Style::Unit, _) => deserialize_unit_struct(params, &cont.attrs),
        }
@@ -459,9 +469,13 @@ fn deserialize_tuple(
    params: &Parameters,
    fields: &[Field],
    cattrs: &attr::Container,
+    has_flatten: bool,
    form: TupleForm,
 ) -> Fragment {
-    assert!(!cattrs.has_flatten());
+    assert!(
+        !has_flatten,
+        "tuples and tuple variants cannot have flatten fields"
+    );

    let field_count = fields
        .iter()
@@ -579,7 +593,10 @@ fn deserialize_tuple_in_place(
    fields: &[Field],
    cattrs: &attr::Container,
 ) -> Fragment {
-    assert!(!cattrs.has_flatten());
+    assert!(
+        !cattrs.has_flatten(),
+        "tuples and tuple variants cannot have flatten fields"
+    );

    let field_count = fields
        .iter()
@@ -910,6 +927,7 @@ fn deserialize_struct(
    params: &Parameters,
    fields: &[Field],
    cattrs: &attr::Container,
+    has_flatten: bool,
    form: StructForm,
 ) -> Fragment {
    let this_type = &params.this_type;
@@ -958,13 +976,13 @@ fn deserialize_struct(
            )
        })
        .collect();
-    let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs);
+    let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs, has_flatten);

    // untagged struct variants do not get a visit_seq method. The same applies to
    // structs that only have a map representation.
    let visit_seq = match form {
        StructForm::Untagged(..) => None,
-        _ if cattrs.has_flatten() => None,
+        _ if has_flatten => None,
        _ => {
            let mut_seq = if field_names_idents.is_empty() {
                quote!(_)
@@ -987,10 +1005,16 @@ fn deserialize_struct(
            })
        }
    };
-    let visit_map = Stmts(deserialize_map(&type_path, params, fields, cattrs));
+    let visit_map = Stmts(deserialize_map(
+        &type_path,
+        params,
+        fields,
+        cattrs,
+        has_flatten,
+    ));

    let visitor_seed = match form {
-        StructForm::ExternallyTagged(..) if cattrs.has_flatten() => Some(quote! {
+        StructForm::ExternallyTagged(..) if has_flatten => Some(quote! {
            impl #de_impl_generics _serde::de::DeserializeSeed<#delife> for __Visitor #de_ty_generics #where_clause {
                type Value = #this_type #ty_generics;

@@ -1005,7 +1029,7 @@ fn deserialize_struct(
        _ => None,
    };

-    let fields_stmt = if cattrs.has_flatten() {
+    let fields_stmt = if has_flatten {
        None
    } else {
        let field_names = field_names_idents
@@ -1025,7 +1049,7 @@ fn deserialize_struct(
        }
    };
    let dispatch = match form {
-        StructForm::Struct if cattrs.has_flatten() => quote! {
+        StructForm::Struct if has_flatten => quote! {
            _serde::Deserializer::deserialize_map(__deserializer, #visitor_expr)
        },
        StructForm::Struct => {
@@ -1034,7 +1058,7 @@ fn deserialize_struct(
                _serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, #visitor_expr)
            }
        }
-        StructForm::ExternallyTagged(_) if cattrs.has_flatten() => quote! {
+        StructForm::ExternallyTagged(_) if has_flatten => quote! {
            _serde::de::VariantAccess::newtype_variant_seed(__variant, #visitor_expr)
        },
        StructForm::ExternallyTagged(_) => quote! {
@@ -1116,7 +1140,7 @@ fn deserialize_struct_in_place(
        })
        .collect();

-    let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs);
+    let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs, false);

    let mut_seq = if field_names_idents.is_empty() {
        quote!(_)
@@ -1210,10 +1234,7 @@ fn deserialize_homogeneous_enum(
    }
 }

-fn prepare_enum_variant_enum(
-    variants: &[Variant],
-    cattrs: &attr::Container,
-) -> (TokenStream, Stmts) {
+fn prepare_enum_variant_enum(variants: &[Variant]) -> (TokenStream, Stmts) {
    let mut deserialized_variants = variants
        .iter()
        .enumerate()
@@ -1247,7 +1268,7 @@ fn prepare_enum_variant_enum(

    let variant_visitor = Stmts(deserialize_generated_identifier(
        &variant_names_idents,
-        cattrs,
+        false, // variant identifiers do not depend on the presence of flatten fields
        true,
        None,
        fallthrough,
@@ -1270,7 +1291,7 @@ fn deserialize_externally_tagged_enum(
    let expecting = format!("enum {}", params.type_name());
    let expecting = cattrs.expecting().unwrap_or(&expecting);

-    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
+    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants);

    // Match arms to extract a variant from a string
    let variant_arms = variants
@@ -1355,7 +1376,7 @@ fn deserialize_internally_tagged_enum(
    cattrs: &attr::Container,
    tag: &str,
 ) -> Fragment {
-    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
+    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants);

    // Match arms to extract a variant from a string
    let variant_arms = variants
@@ -1409,7 +1430,7 @@ fn deserialize_adjacently_tagged_enum(
        split_with_de_lifetime(params);
    let delife = params.borrowed.de_lifetime();

-    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
+    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants);

    let variant_arms: &Vec<_> = &variants
        .iter()
@@ -1810,12 +1831,14 @@ fn deserialize_externally_tagged_variant(
            params,
            &variant.fields,
            cattrs,
+            variant.attrs.has_flatten(),
            TupleForm::ExternallyTagged(variant_ident),
        ),
        Style::Struct => deserialize_struct(
            params,
            &variant.fields,
            cattrs,
+            variant.attrs.has_flatten(),
            StructForm::ExternallyTagged(variant_ident),
        ),
    }
@@ -1859,6 +1882,7 @@ fn deserialize_internally_tagged_variant(
            params,
            &variant.fields,
            cattrs,
+            variant.attrs.has_flatten(),
            StructForm::InternallyTagged(variant_ident, deserializer),
        ),
        Style::Tuple => unreachable!("checked in serde_derive_internals"),
@@ -1909,12 +1933,14 @@ fn deserialize_untagged_variant(
            params,
            &variant.fields,
            cattrs,
+            variant.attrs.has_flatten(),
            TupleForm::Untagged(variant_ident, deserializer),
        ),
        Style::Struct => deserialize_struct(
            params,
            &variant.fields,
            cattrs,
+            variant.attrs.has_flatten(),
            StructForm::Untagged(variant_ident, deserializer),
        ),
    }
@@ -1985,7 +2011,7 @@ fn deserialize_untagged_newtype_variant(

 fn deserialize_generated_identifier(
    fields: &[(&str, Ident, &BTreeSet<String>)],
-    cattrs: &attr::Container,
+    has_flatten: bool,
    is_variant: bool,
    ignore_variant: Option<TokenStream>,
    fallthrough: Option<TokenStream>,
@@ -1999,11 +2025,11 @@ fn deserialize_generated_identifier(
        is_variant,
        fallthrough,
        None,
-        !is_variant && cattrs.has_flatten(),
+        !is_variant && has_flatten,
        None,
    ));

-    let lifetime = if !is_variant && cattrs.has_flatten() {
+    let lifetime = if !is_variant && has_flatten {
        Some(quote!(<'de>))
    } else {
        None
@@ -2043,8 +2069,9 @@ fn deserialize_generated_identifier(
 fn deserialize_field_identifier(
    fields: &[(&str, Ident, &BTreeSet<String>)],
    cattrs: &attr::Container,
+    has_flatten: bool,
 ) -> Stmts {
-    let (ignore_variant, fallthrough) = if cattrs.has_flatten() {
+    let (ignore_variant, fallthrough) = if has_flatten {
        let ignore_variant = quote!(__other(_serde::__private::de::Content<'de>),);
        let fallthrough = quote!(_serde::__private::Ok(__Field::__other(__value)));
        (Some(ignore_variant), Some(fallthrough))
@@ -2058,7 +2085,7 @@ fn deserialize_field_identifier(

    Stmts(deserialize_generated_identifier(
        fields,
-        cattrs,
+        has_flatten,
        false,
        ignore_variant,
        fallthrough,
@@ -2460,6 +2487,7 @@ fn deserialize_map(
    params: &Parameters,
    fields: &[Field],
    cattrs: &attr::Container,
+    has_flatten: bool,
 ) -> Fragment {
    // Create the field names for the fields.
    let fields_names: Vec<_> = fields
@@ -2480,7 +2508,7 @@ fn deserialize_map(
        });

    // Collect contents for flatten fields into a buffer
-    let let_collect = if cattrs.has_flatten() {
+    let let_collect = if has_flatten {
        Some(quote! {
            let mut __collect = _serde::__private::Vec::<_serde::__private::Option<(
                _serde::__private::de::Content,
@@ -2532,7 +2560,7 @@ fn deserialize_map(
        });

    // Visit ignored values to consume them
-    let ignored_arm = if cattrs.has_flatten() {
+    let ignored_arm = if has_flatten {
        Some(quote! {
            __Field::__other(__name) => {
                __collect.push(_serde::__private::Some((
@@ -2602,7 +2630,7 @@ fn deserialize_map(
            }
        });

-    let collected_deny_unknown_fields = if cattrs.has_flatten() && cattrs.deny_unknown_fields() {
+    let collected_deny_unknown_fields = if has_flatten && cattrs.deny_unknown_fields() {
        Some(quote! {
            if let _serde::__private::Some(_serde::__private::Some((__key, _))) =
                __collect.into_iter().filter(_serde::__private::Option::is_some).next()
@@ -2678,7 +2706,10 @@ fn deserialize_map_in_place(
    fields: &[Field],
    cattrs: &attr::Container,
 ) -> Fragment {
-    assert!(!cattrs.has_flatten());
+    assert!(
+        !cattrs.has_flatten(),
+        "inplace deserialization of maps does not support flatten fields"
+    );

    // Create the field names for the fields.
    let fields_names: Vec<_> = fields
@@ -85,6 +85,7 @@ impl<'a> Container<'a> {
                    for field in &mut variant.fields {
                        if field.attrs.flatten() {
                            has_flatten = true;
+                            variant.attrs.mark_has_flatten();
                        }
                        field.attrs.rename_by_rules(
                            variant
@@ -185,8 +185,8 @@ impl Name {

 #[derive(Copy, Clone)]
 pub struct RenameAllRules {
-    serialize: RenameRule,
-    deserialize: RenameRule,
+    pub serialize: RenameRule,
+    pub deserialize: RenameRule,
 }

 impl RenameAllRules {
@@ -216,6 +216,22 @@ pub struct Container {
    type_into: Option<syn::Type>,
    remote: Option<syn::Path>,
    identifier: Identifier,
+    /// True if container is a struct and has a field with `#[serde(flatten)]`,
+    /// or is an enum with a struct variant which has a field with
+    /// `#[serde(flatten)]`.
+    ///
+    /// ```ignore
+    /// struct Container {
+    ///     #[serde(flatten)]
+    ///     some_field: (),
+    /// }
+    /// enum Container {
+    ///     Variant {
+    ///         #[serde(flatten)]
+    ///         some_field: (),
+    ///     },
+    /// }
+    /// ```
    has_flatten: bool,
    serde_path: Option<syn::Path>,
    is_packed: bool,
@@ -794,6 +810,18 @@ pub struct Variant {
    rename_all_rules: RenameAllRules,
    ser_bound: Option<Vec<syn::WherePredicate>>,
    de_bound: Option<Vec<syn::WherePredicate>>,
+    /// True if variant is a struct variant which contains a field with
+    /// `#[serde(flatten)]`.
+    ///
+    /// ```ignore
+    /// enum Enum {
+    ///     Variant {
+    ///         #[serde(flatten)]
+    ///         some_field: (),
+    ///     },
+    /// }
+    /// ```
+    has_flatten: bool,
    skip_deserializing: bool,
    skip_serializing: bool,
    other: bool,
@@ -963,6 +991,7 @@ impl Variant {
            },
            ser_bound: ser_bound.get(),
            de_bound: de_bound.get(),
+            has_flatten: false,
            skip_deserializing: skip_deserializing.get(),
            skip_serializing: skip_serializing.get(),
            other: other.get(),
@@ -1005,6 +1034,14 @@ impl Variant {
        self.de_bound.as_ref().map(|vec| &vec[..])
    }

+    pub fn has_flatten(&self) -> bool {
+        self.has_flatten
+    }
+
+    pub fn mark_has_flatten(&mut self) {
+        self.has_flatten = true;
+    }
+
    pub fn skip_deserializing(&self) -> bool {
        self.skip_deserializing
    }
@@ -84,7 +84,7 @@ impl ReplaceReceiver<'_> {
            self.visit_type_mut_impl(ty);
            return;
        };
-        *ty = self.self_ty(span).into();
+        *ty = Type::Path(self.self_ty(span));
    }

    // `Self::Assoc` -> `<Receiver>::Assoc`
@@ -13,7 +13,7 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html

-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.201")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.206")]
 #![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 // Ignored clippy lints
 #![allow(
@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive_internals"
-version = "0.29.0"
+version = "0.29.1"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 description = "AST representation used by Serde derive macros. Unstable."
 documentation = "https://docs.rs/serde_derive_internals"
@@ -1,4 +1,4 @@
-#![doc(html_root_url = "https://docs.rs/serde_derive_internals/0.29.0")]
+#![doc(html_root_url = "https://docs.rs/serde_derive_internals/0.29.1")]
 #![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 // Ignored clippy lints
 #![allow(
@@ -18,4 +18,4 @@ rustversion = "1.0"
 serde = { path = "../serde", features = ["rc"] }
 serde_derive = { path = "../serde_derive", features = ["deserialize_in_place"] }
 serde_test = "1.0.176"
-trybuild = { version = "1.0.66", features = ["diff"] }
+trybuild = { version = "1.0.97", features = ["diff"] }
@@ -23,21 +23,21 @@ fn panic(_info: &core::panic::PanicInfo) -> ! {
 use serde_derive::{Deserialize, Serialize};

 #[derive(Serialize, Deserialize)]
-struct Unit;
+pub struct Unit;

 #[derive(Serialize, Deserialize)]
-struct Newtype(u8);
+pub struct Newtype(u8);

 #[derive(Serialize, Deserialize)]
-struct Tuple(u8, u8);
+pub struct Tuple(u8, u8);

 #[derive(Serialize, Deserialize)]
-struct Struct {
+pub struct Struct {
    f: u8,
 }

 #[derive(Serialize, Deserialize)]
-enum Enum {
+pub enum Enum {
    Unit,
    Newtype(u8),
    Tuple(u8, u8),
@@ -1,6 +1,6 @@
-#[cfg_attr(target_os = "emscripten", ignore)]
-#[rustversion::attr(not(nightly), ignore)]
-#[cfg_attr(miri, ignore)]
+#[cfg_attr(target_os = "emscripten", ignore = "disabled on Emscripten")]
+#[rustversion::attr(not(nightly), ignore = "requires nightly")]
+#[cfg_attr(miri, ignore = "incompatible with miri")]
 #[allow(unused_attributes)]
 #[test]
 fn ui() {
@@ -0,0 +1,66 @@
+#![allow(dead_code)] // we do not read enum fields
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+pub struct Nested;
+
+#[derive(Deserialize)]
+pub enum ExternallyTagged1 {
+    Tuple(f64, String),
+    Flatten {
+        #[serde(flatten)]
+        nested: Nested,
+    },
+}
+
+#[derive(Deserialize)]
+pub enum ExternallyTagged2 {
+    Flatten {
+        #[serde(flatten)]
+        nested: Nested,
+    },
+    Tuple(f64, String),
+}
+
+// Internally tagged enums cannot contain tuple variants so not tested here
+
+#[derive(Deserialize)]
+#[serde(tag = "tag", content = "content")]
+pub enum AdjacentlyTagged1 {
+    Tuple(f64, String),
+    Flatten {
+        #[serde(flatten)]
+        nested: Nested,
+    },
+}
+
+#[derive(Deserialize)]
+#[serde(tag = "tag", content = "content")]
+pub enum AdjacentlyTagged2 {
+    Flatten {
+        #[serde(flatten)]
+        nested: Nested,
+    },
+    Tuple(f64, String),
+}
+
+#[derive(Deserialize)]
+#[serde(untagged)]
+pub enum Untagged1 {
+    Tuple(f64, String),
+    Flatten {
+        #[serde(flatten)]
+        nested: Nested,
+    },
+}
+
+#[derive(Deserialize)]
+#[serde(untagged)]
+pub enum Untagged2 {
+    Flatten {
+        #[serde(flatten)]
+        nested: Nested,
+    },
+    Tuple(f64, String),
+}
@@ -0,0 +1,41 @@
+use serde_derive::{Serialize, Deserialize};
+use serde_test::{assert_tokens, Token};
+
+#[derive(Serialize, Deserialize, Debug, PartialEq)]
+enum Enum {
+    Simple {
+        a: i32,
+    },
+    Flatten {
+        #[serde(flatten)]
+        flatten: (),
+        a: i32,
+    },
+}
+
+#[test]
+fn simple_variant() {
+    assert_tokens(
+        &Enum::Simple { a: 42 },
+        &[
+            Token::StructVariant { name: "Enum", variant: "Simple", len: 1 },
+            Token::Str("a"),
+            Token::I32(42),
+            Token::StructVariantEnd,
+        ]
+    );
+}
+
+#[test]
+fn flatten_variant() {
+    assert_tokens(
+        &Enum::Flatten { flatten: (), a: 42 },
+        &[
+            Token::NewtypeVariant { name: "Enum", variant: "Flatten" },
+            Token::Map { len: None },
+            Token::Str("a"),
+            Token::I32(42),
+            Token::MapEnd,
+        ]
+    );
+}
@@ -0,0 +1,18 @@
+#![allow(dead_code)] // we do not read enum fields
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+pub enum A {
+    B {
+        c: String,
+    },
+    D {
+        #[serde(flatten)]
+        e: E,
+    },
+}
+
+#[derive(Deserialize)]
+pub struct E {}
@@ -2380,6 +2380,56 @@ fn test_partially_untagged_enum_desugared() {
    );
 }

+// Regression test for https://github.com/serde-rs/serde/issues/1904
+#[test]
+fn test_enum_tuple_and_struct_with_flatten() {
+    #[derive(Serialize, Deserialize, PartialEq, Debug)]
+    enum Outer {
+        Tuple(f64, i32),
+        Flatten {
+            #[serde(flatten)]
+            nested: Nested,
+        },
+    }
+
+    #[derive(Serialize, Deserialize, PartialEq, Debug)]
+    struct Nested {
+        a: i32,
+        b: i32,
+    }
+
+    assert_tokens(
+        &Outer::Tuple(1.2, 3),
+        &[
+            Token::TupleVariant {
+                name: "Outer",
+                variant: "Tuple",
+                len: 2,
+            },
+            Token::F64(1.2),
+            Token::I32(3),
+            Token::TupleVariantEnd,
+        ],
+    );
+    assert_tokens(
+        &Outer::Flatten {
+            nested: Nested { a: 1, b: 2 },
+        },
+        &[
+            Token::NewtypeVariant {
+                name: "Outer",
+                variant: "Flatten",
+            },
+            Token::Map { len: None },
+            Token::Str("a"),
+            Token::I32(1),
+            Token::Str("b"),
+            Token::I32(2),
+            Token::MapEnd,
+        ],
+    );
+}
+
 #[test]
 fn test_partially_untagged_internally_tagged_enum() {
    #[derive(Serialize, Deserialize, PartialEq, Debug)]
@@ -162,7 +162,7 @@ fn test_cow() {
 #[test]
 fn test_lifetimes() {
    #[derive(Deserialize)]
-    struct Cows<'a, 'b> {
+    pub struct Cows<'a, 'b> {
        _copied: Cow<'a, str>,

        #[serde(borrow)]
@@ -178,7 +178,7 @@ fn test_lifetimes() {
    }

    #[derive(Deserialize)]
-    struct Wrap<'a, 'b> {
+    pub struct Wrap<'a, 'b> {
        #[serde(borrow = "'b")]
        _cows: Cows<'a, 'b>,
    }
@@ -93,7 +93,7 @@ struct StructSkipDefault {

 #[derive(PartialEq, Debug, Deserialize)]
 #[serde(default)]
-struct StructSkipDefaultGeneric<T> {
+pub struct StructSkipDefaultGeneric<T> {
    #[serde(skip_deserializing)]
    t: T,
 }
@@ -4,6 +4,7 @@

 #![deny(warnings)]
 #![allow(
+    confusable_idents,
    unknown_lints,
    mixed_script_confusables,
    clippy::derive_partial_eq_without_eq,
@@ -19,6 +20,7 @@
    clippy::trivially_copy_pass_by_ref,
    clippy::type_repetition_in_bounds
 )]
+#![deny(clippy::collection_is_never_read)]

 use serde::de::{Deserialize, DeserializeOwned, Deserializer};
 use serde::ser::{Serialize, Serializer};
@@ -287,60 +289,60 @@ fn test_gen() {
    assert::<EmptyEnumVariant>();

    #[derive(Serialize, Deserialize)]
-    struct NonAsciiIdents {
+    pub struct NonAsciiIdents {
        σ: f64,
    }

    #[derive(Serialize, Deserialize)]
-    struct EmptyBraced {}
+    pub struct EmptyBraced {}

    #[derive(Serialize, Deserialize)]
    #[serde(deny_unknown_fields)]
-    struct EmptyBracedDenyUnknown {}
+    pub struct EmptyBracedDenyUnknown {}

    #[derive(Serialize, Deserialize)]
-    struct BracedSkipAll {
+    pub struct BracedSkipAll {
        #[serde(skip_deserializing)]
        f: u8,
    }

    #[derive(Serialize, Deserialize)]
    #[serde(deny_unknown_fields)]
-    struct BracedSkipAllDenyUnknown {
+    pub struct BracedSkipAllDenyUnknown {
        #[serde(skip_deserializing)]
        f: u8,
    }

    #[derive(Serialize, Deserialize)]
-    struct EmptyTuple();
+    pub struct EmptyTuple();

    #[derive(Serialize, Deserialize)]
    #[serde(deny_unknown_fields)]
-    struct EmptyTupleDenyUnknown();
+    pub struct EmptyTupleDenyUnknown();

    #[derive(Serialize, Deserialize)]
-    struct TupleSkipAll(#[serde(skip_deserializing)] u8);
+    pub struct TupleSkipAll(#[serde(skip_deserializing)] u8);

    #[derive(Serialize, Deserialize)]
    #[serde(deny_unknown_fields)]
-    struct TupleSkipAllDenyUnknown(#[serde(skip_deserializing)] u8);
+    pub struct TupleSkipAllDenyUnknown(#[serde(skip_deserializing)] u8);

    #[derive(Serialize, Deserialize)]
-    enum EmptyEnum {}
+    pub enum EmptyEnum {}

    #[derive(Serialize, Deserialize)]
    #[serde(deny_unknown_fields)]
-    enum EmptyEnumDenyUnknown {}
+    pub enum EmptyEnumDenyUnknown {}

    #[derive(Serialize, Deserialize)]
-    enum EnumSkipAll {
+    pub enum EnumSkipAll {
        #[serde(skip_deserializing)]
        #[allow(dead_code)]
        Variant,
    }

    #[derive(Serialize, Deserialize)]
-    enum EmptyVariants {
+    pub enum EmptyVariants {
        Braced {},
        Tuple(),
        BracedSkip {
@@ -352,7 +354,7 @@ fn test_gen() {

    #[derive(Serialize, Deserialize)]
    #[serde(deny_unknown_fields)]
-    enum EmptyVariantsDenyUnknown {
+    pub enum EmptyVariantsDenyUnknown {
        Braced {},
        Tuple(),
        BracedSkip {
@@ -364,21 +366,21 @@ fn test_gen() {

    #[derive(Serialize, Deserialize)]
    #[serde(deny_unknown_fields)]
-    struct UnitDenyUnknown;
+    pub struct UnitDenyUnknown;

    #[derive(Serialize, Deserialize)]
-    struct EmptyArray {
+    pub struct EmptyArray {
        empty: [X; 0],
    }

-    enum Or<A, B> {
+    pub enum Or<A, B> {
        A(A),
        B(B),
    }

    #[derive(Serialize, Deserialize)]
    #[serde(untagged, remote = "Or")]
-    enum OrDef<A, B> {
+    pub enum OrDef<A, B> {
        A(A),
        B(B),
    }
@@ -390,7 +392,7 @@ fn test_gen() {
    struct StrDef<'a>(&'a str);

    #[derive(Serialize, Deserialize)]
-    struct Remote<'a> {
+    pub struct Remote<'a> {
        #[serde(with = "OrDef")]
        or: Or<u8, bool>,
        #[serde(borrow, with = "StrDef")]
@@ -398,7 +400,7 @@ fn test_gen() {
    }

    #[derive(Serialize, Deserialize)]
-    enum BorrowVariant<'a> {
+    pub enum BorrowVariant<'a> {
        #[serde(borrow, with = "StrDef")]
        S(Str<'a>),
    }
@@ -415,14 +417,14 @@ fn test_gen() {

    // This would not work if SDef::serialize / deserialize are private.
    #[derive(Serialize, Deserialize)]
-    struct RemoteVisibility {
+    pub struct RemoteVisibility {
        #[serde(with = "vis::SDef")]
        s: vis::S,
    }

    #[derive(Serialize, Deserialize)]
    #[serde(remote = "Self")]
-    struct RemoteSelf;
+    pub struct RemoteSelf;

    #[derive(Serialize, Deserialize)]
    enum ExternallyTaggedVariantWith {
@@ -547,25 +549,25 @@ fn test_gen() {

    #[derive(Serialize, Deserialize)]
    #[serde(deny_unknown_fields)]
-    struct FlattenDenyUnknown<T> {
+    pub struct FlattenDenyUnknown<T> {
        #[serde(flatten)]
        t: T,
    }

    #[derive(Serialize, Deserialize)]
-    struct StaticStrStruct<'a> {
+    pub struct StaticStrStruct<'a> {
        a: &'a str,
        b: &'static str,
    }

    #[derive(Serialize, Deserialize)]
-    struct StaticStrTupleStruct<'a>(&'a str, &'static str);
+    pub struct StaticStrTupleStruct<'a>(&'a str, &'static str);

    #[derive(Serialize, Deserialize)]
-    struct StaticStrNewtypeStruct(&'static str);
+    pub struct StaticStrNewtypeStruct(&'static str);

    #[derive(Serialize, Deserialize)]
-    enum StaticStrEnum<'a> {
+    pub enum StaticStrEnum<'a> {
        Struct { a: &'a str, b: &'static str },
        Tuple(&'a str, &'static str),
        Newtype(&'static str),
@@ -639,6 +641,7 @@ fn test_gen() {
            use serde_derive::{Deserialize, Serialize};

            #[derive(Serialize, Deserialize)]
+            #[allow(dead_code)]
            struct Restricted {
                pub(super) a: usize,
                pub(in super::inner) b: usize,
@@ -648,7 +651,7 @@ fn test_gen() {

    #[derive(Deserialize)]
    #[serde(tag = "t", content = "c")]
-    enum AdjacentlyTaggedVoid {}
+    pub enum AdjacentlyTaggedVoid {}

    #[derive(Serialize, Deserialize)]
    enum SkippedVariant<T> {
@@ -661,14 +664,13 @@ fn test_gen() {
    assert::<SkippedVariant<X>>();

    #[derive(Deserialize)]
-    struct ImplicitlyBorrowedOption<'a> {
-        #[allow(dead_code)]
+    pub struct ImplicitlyBorrowedOption<'a> {
        option: std::option::Option<&'a str>,
    }

    #[derive(Serialize, Deserialize)]
    #[serde(untagged)]
-    enum UntaggedNewtypeVariantWith {
+    pub enum UntaggedNewtypeVariantWith {
        Newtype(
            #[serde(serialize_with = "ser_x")]
            #[serde(deserialize_with = "de_x")]
@@ -678,7 +680,7 @@ fn test_gen() {

    #[derive(Serialize, Deserialize)]
    #[serde(transparent)]
-    struct TransparentWith {
+    pub struct TransparentWith {
        #[serde(serialize_with = "ser_x")]
        #[serde(deserialize_with = "de_x")]
        x: X,
@@ -700,35 +702,49 @@ fn test_gen() {
    }

    #[derive(Deserialize)]
-    struct RelObject<'a> {
-        #[allow(dead_code)]
+    pub struct RelObject<'a> {
        ty: &'a str,
-        #[allow(dead_code)]
        id: String,
    }

    #[derive(Serialize, Deserialize)]
-    struct FlattenSkipSerializing<T> {
+    pub struct FlattenSkipSerializing<T> {
        #[serde(flatten, skip_serializing)]
        #[allow(dead_code)]
        flat: T,
    }

    #[derive(Serialize, Deserialize)]
-    struct FlattenSkipSerializingIf<T> {
+    pub struct FlattenSkipSerializingIf<T> {
        #[serde(flatten, skip_serializing_if = "StdOption::is_none")]
        flat: StdOption<T>,
    }

+    #[allow(clippy::collection_is_never_read)] // FIXME
+    const _: () = {
+        #[derive(Serialize, Deserialize)]
+        pub struct FlattenSkipDeserializing<T> {
+            #[serde(flatten, skip_deserializing)]
+            flat: T,
+        }
+    };
+
    #[derive(Serialize, Deserialize)]
-    struct FlattenSkipDeserializing<T> {
-        #[serde(flatten, skip_deserializing)]
-        flat: T,
+    #[serde(untagged)]
+    pub enum Inner<T> {
+        Builder {
+            s: T,
+            #[serde(flatten)]
+            o: T,
+        },
+        Default {
+            s: T,
+        },
    }

    // https://github.com/serde-rs/serde/issues/1804
    #[derive(Serialize, Deserialize)]
-    enum Message {
+    pub enum Message {
        #[serde(skip)]
        #[allow(dead_code)]
        String(String),
@@ -747,8 +763,7 @@ fn test_gen() {
    macro_rules! deriving {
        ($field:ty) => {
            #[derive(Deserialize)]
-            struct MacroRules<'a> {
-                #[allow(dead_code)]
+            pub struct MacroRules<'a> {
                field: $field,
            }
        };
@@ -763,22 +778,20 @@ fn test_gen() {
    }

    #[derive(Deserialize)]
-    struct BorrowLifetimeInsideMacro<'a> {
+    pub struct BorrowLifetimeInsideMacro<'a> {
        #[serde(borrow = "'a")]
-        #[allow(dead_code)]
-        f: mac!(Cow<'a, str>),
+        pub f: mac!(Cow<'a, str>),
    }

    #[derive(Serialize)]
-    #[allow(dead_code)]
-    struct Struct {
+    pub struct Struct {
        #[serde(serialize_with = "vec_first_element")]
-        vec: Vec<Self>,
+        pub vec: Vec<Self>,
    }

    #[derive(Deserialize)]
    #[serde(bound(deserialize = "[&'de str; N]: Copy"))]
-    struct GenericUnitStruct<const N: usize>;
+    pub struct GenericUnitStruct<const N: usize>;
 }

 //////////////////////////////////////////////////////////////////////////
@@ -865,7 +878,7 @@ where

 #[derive(Debug, PartialEq, Deserialize)]
 #[serde(tag = "tag")]
-enum InternallyTagged {
+pub enum InternallyTagged {
    #[serde(deserialize_with = "deserialize_generic")]
    Unit,

@@ -7,14 +7,17 @@ mod remote {

    pub struct PrimitivePriv(u8);

+    #[allow(dead_code)]
    pub struct PrimitivePub(pub u8);

    pub struct NewtypePriv(Unit);

+    #[allow(dead_code)]
    pub struct NewtypePub(pub Unit);

    pub struct TuplePriv(u8, Unit);

+    #[allow(dead_code)]
    pub struct TuplePub(pub u8, pub Unit);

    pub struct StructPriv {
@@ -22,6 +25,7 @@ mod remote {
        b: Unit,
    }

+    #[allow(dead_code)]
    pub struct StructPub {
        pub a: u8,
        pub b: Unit,
@@ -86,12 +90,14 @@ mod remote {
        }
    }

+    #[allow(dead_code)]
    pub enum EnumGeneric<T> {
        Variant(T),
    }
 }

 #[derive(Serialize, Deserialize)]
+#[allow(dead_code)]
 struct Test {
    #[serde(with = "UnitDef")]
    unit: remote::Unit,
@@ -132,6 +138,7 @@ struct Test {

 #[derive(Serialize, Deserialize)]
 #[serde(remote = "remote::Unit")]
+#[allow(dead_code)]
 struct UnitDef;

 #[derive(Serialize, Deserialize)]
@@ -140,6 +147,7 @@ struct PrimitivePrivDef(#[serde(getter = "remote::PrimitivePriv::get")] u8);

 #[derive(Serialize, Deserialize)]
 #[serde(remote = "remote::PrimitivePub")]
+#[allow(dead_code)]
 struct PrimitivePubDef(u8);

 #[derive(Serialize, Deserialize)]
@@ -148,6 +156,7 @@ struct NewtypePrivDef(#[serde(getter = "remote::NewtypePriv::get", with = "UnitD

 #[derive(Serialize, Deserialize)]
 #[serde(remote = "remote::NewtypePub")]
+#[allow(dead_code)]
 struct NewtypePubDef(#[serde(with = "UnitDef")] remote::Unit);

 #[derive(Serialize, Deserialize)]
@@ -159,6 +168,7 @@ struct TuplePrivDef(

 #[derive(Serialize, Deserialize)]
 #[serde(remote = "remote::TuplePub")]
+#[allow(dead_code)]
 struct TuplePubDef(u8, #[serde(with = "UnitDef")] remote::Unit);

 #[derive(Serialize, Deserialize)]
@@ -174,6 +184,7 @@ struct StructPrivDef {

 #[derive(Serialize, Deserialize)]
 #[serde(remote = "remote::StructPub")]
+#[allow(dead_code)]
 struct StructPubDef {
    a: u8,

@@ -190,17 +201,20 @@ struct StructGenericWithGetterDef<T> {

 #[derive(Serialize, Deserialize)]
 #[serde(remote = "remote::StructGeneric<u8>")]
+#[allow(dead_code)]
 struct StructConcrete {
    value: u8,
 }

 #[derive(Serialize, Deserialize)]
 #[serde(remote = "remote::EnumGeneric<u8>")]
+#[allow(dead_code)]
 enum EnumConcrete {
    Variant(u8),
 }

 #[derive(Debug)]
+#[allow(dead_code)]
 enum ErrorKind {
    NotFound,
    PermissionDenied,
@@ -211,6 +225,7 @@ enum ErrorKind {
 #[derive(Serialize, Deserialize)]
 #[serde(remote = "ErrorKind")]
 #[non_exhaustive]
+#[allow(dead_code)]
 enum ErrorKindDef {
    NotFound,
    PermissionDenied,
@@ -41,7 +41,7 @@ fn test_self() {
    }

    #[derive(Deserialize, Serialize)]
-    struct Tuple(
+    pub struct Tuple(
        Box<Self>,
        Box<<Self as Trait>::Assoc>,
        [(); Self::ASSOC],
@@ -60,7 +60,7 @@ fn test_self() {
    }

    #[derive(Deserialize, Serialize)]
-    enum Enum {
+    pub enum Enum {
        Struct {
            _f1: Box<Self>,
            _f2: Box<<Self as Trait>::Assoc>,
@@ -0,0 +1,23 @@
+use serde::de::Deserialize;
+use serde::ser::Serialize;
+
+fn to_string<T>(_: &T) -> String
+where
+    T: Serialize,
+{
+    unimplemented!()
+}
+
+fn from_str<'de, T>(_: &'de str) -> T
+where
+    T: Deserialize<'de>,
+{
+    unimplemented!()
+}
+
+struct MyStruct;
+
+fn main() {
+    to_string(&MyStruct);
+    let _: MyStruct = from_str("");
+}
@@ -0,0 +1,55 @@
+error[E0277]: the trait bound `MyStruct: Serialize` is not satisfied
+  --> tests/ui/on_unimplemented.rs:21:15
+   |
+21 |     to_string(&MyStruct);
+   |     --------- ^^^^^^^^^ the trait `Serialize` is not implemented for `MyStruct`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = note: for local types consider adding `#[derive(serde::Serialize)]` to your `MyStruct` type
+   = note: for types from other crates check whether the crate offers a `serde` feature flag
+   = help: the following other types implement trait `Serialize`:
+             &'a T
+             &'a mut T
+             ()
+             (T,)
+             (T0, T1)
+             (T0, T1, T2)
+             (T0, T1, T2, T3)
+             (T0, T1, T2, T3, T4)
+           and $N others
+note: required by a bound in `to_string`
+  --> tests/ui/on_unimplemented.rs:6:8
+   |
+4  | fn to_string<T>(_: &T) -> String
+   |    --------- required by a bound in this function
+5  | where
+6  |     T: Serialize,
+   |        ^^^^^^^^^ required by this bound in `to_string`
+
+error[E0277]: the trait bound `MyStruct: Deserialize<'_>` is not satisfied
+  --> tests/ui/on_unimplemented.rs:22:23
+   |
+22 |     let _: MyStruct = from_str("");
+   |                       ^^^^^^^^^^^^ the trait `Deserialize<'_>` is not implemented for `MyStruct`
+   |
+   = note: for local types consider adding `#[derive(serde::Deserialize)]` to your `MyStruct` type
+   = note: for types from other crates check whether the crate offers a `serde` feature flag
+   = help: the following other types implement trait `Deserialize<'de>`:
+             &'a Path
+             &'a [u8]
+             &'a str
+             ()
+             (T,)
+             (T0, T1)
+             (T0, T1, T2)
+             (T0, T1, T2, T3)
+           and $N others
+note: required by a bound in `from_str`
+  --> tests/ui/on_unimplemented.rs:13:8
+   |
+11 | fn from_str<'de, T>(_: &'de str) -> T
+   |    -------- required by a bound in this function
+12 | where
+13 |     T: Deserialize<'de>,
+   |        ^^^^^^^^^^^^^^^^ required by this bound in `from_str`