Release 1.0.206

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)]`

.github/workflows/ci.yml

@@ -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:

crates-io.md

@@ -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

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.198"
+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 = "=1.0.198", path = "../serde_derive" }
+serde_derive = { version = "=1.0.206", path = "../serde_derive" }
 
 
 ### FEATURES #################################################################

serde/build.rs

@@ -13,6 +13,21 @@ fn main() {
         None => return,
     };
 
+    if minor >= 77 {
+        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)");
+        println!("cargo:rustc-check-cfg=cfg(no_serde_derive)");
+        println!("cargo:rustc-check-cfg=cfg(no_std_atomic)");
+        println!("cargo:rustc-check-cfg=cfg(no_std_atomic64)");
+        println!("cargo:rustc-check-cfg=cfg(no_systemtime_checked_add)");
+        println!("cargo:rustc-check-cfg=cfg(no_target_has_atomic)");
+    }
+
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
@@ -70,6 +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> {

serde/src/de/impls.rs

@@ -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

serde/src/de/mod.rs

@@ -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,
@@ -2312,13 +2319,17 @@ impl Display for WithDecimalPoint {
             }
         }
 
-        let mut writer = LookForDecimalPoint {
-            formatter,
-            has_decimal_point: false,
-        };
-        tri!(write!(writer, "{}", self.0));
-        if !writer.has_decimal_point {
-            tri!(formatter.write_str(".0"));
+        if self.0.is_finite() {
+            let mut writer = LookForDecimalPoint {
+                formatter,
+                has_decimal_point: false,
+            };
+            tri!(write!(writer, "{}", self.0));
+            if !writer.has_decimal_point {
+                tri!(formatter.write_str(".0"));
+            }
+        } else {
+            tri!(write!(formatter, "{}", self.0));
         }
         Ok(())
     }

serde/src/de/value.rs

@@ -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,

serde/src/lib.rs

@@ -95,16 +95,17 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.198")]
+#![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(
@@ -118,6 +119,7 @@
     // integer and float ser/de requires these sorts of casts
     clippy::cast_possible_truncation,
     clippy::cast_possible_wrap,
+    clippy::cast_precision_loss,
     clippy::cast_sign_loss,
     // things are often more readable this way
     clippy::cast_lossless,
@@ -329,7 +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")))]

serde/src/macros.rs

@@ -123,7 +123,7 @@ macro_rules! forward_to_deserialize_any {
 macro_rules! forward_to_deserialize_any_method {
     ($func:ident<$l:tt, $v:ident>($($arg:ident : $ty:ty),*)) => {
         #[inline]
-        fn $func<$v>(self, $($arg: $ty,)* visitor: $v) -> $crate::__private::Result<$v::Value, Self::Error>
+        fn $func<$v>(self, $($arg: $ty,)* visitor: $v) -> $crate::__private::Result<$v::Value, <Self as $crate::de::Deserializer<$l>>::Error>
         where
             $v: $crate::de::Visitor<$l>,
         {

serde/src/private/ser.rs

@@ -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> {

serde/src/ser/impls.rs

@@ -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

serde/src/ser/mod.rs

@@ -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.
     ///

serde_derive/Cargo.toml

@@ -1,11 +1,12 @@
 [package]
 name = "serde_derive"
-version = "1.0.198"
+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)]"
 documentation = "https://serde.rs/derive.html"
 edition = "2015"
+exclude = ["build.rs"]
 homepage = "https://serde.rs"
 keywords = ["serde", "serialization", "no_std", "derive"]
 license = "MIT OR Apache-2.0"

serde_derive/build.rs

@@ -0,0 +1,8 @@
+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)");
+}

serde_derive/src/de.rs

@@ -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

serde_derive/src/internals/ast.rs

@@ -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

serde_derive/src/internals/attr.rs

@@ -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
     }

serde_derive/src/internals/receiver.rs

@@ -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`

serde_derive/src/lib.rs

@@ -13,7 +13,8 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.198")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.206")]
+#![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 // Ignored clippy lints
 #![allow(
     // clippy false positive: https://github.com/rust-lang/rust-clippy/issues/7054

serde_derive_internals/Cargo.toml

@@ -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"

serde_derive_internals/build.rs

@@ -1,9 +1,17 @@
 use std::path::Path;
 
 fn main() {
+    // Warning: build.rs is not published to crates.io.
+
     println!("cargo:rerun-if-changed=build.rs");
     println!("cargo:rerun-if-changed=src/mod.rs");
 
+    println!("cargo:rustc-cfg=check_cfg");
+    println!("cargo:rustc-check-cfg=cfg(check_cfg)");
+    println!("cargo:rustc-check-cfg=cfg(exhaustive)");
+    println!("cargo:rustc-check-cfg=cfg(serde_build_from_git)");
+    println!("cargo:rustc-check-cfg=cfg(feature, values(\"deserialize_in_place\"))");
+
     // Sometimes on Windows the git checkout does not correctly wire up the
     // symlink from serde_derive_internals/src to serde_derive/src/internals.
     // When this happens we'll just build based on relative paths within the git

serde_derive_internals/lib.rs

@@ -1,4 +1,5 @@
-#![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(
     clippy::cognitive_complexity,

test_suite/Cargo.toml

@@ -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"] }

test_suite/no_std/src/main.rs

@@ -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),

test_suite/tests/compiletest.rs

@@ -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() {

test_suite/tests/regression/issue1904.rs

@@ -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),
+}

test_suite/tests/regression/issue2565.rs

@@ -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,
+        ]
+    );
+}

test_suite/tests/regression/issue2792.rs

@@ -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 {}

test_suite/tests/test_annotations.rs

@@ -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)]

test_suite/tests/test_borrow.rs

@@ -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>,
     }

test_suite/tests/test_de.rs

@@ -93,7 +93,7 @@ struct StructSkipDefault {
 
 #[derive(PartialEq, Debug, Deserialize)]
 #[serde(default)]
-struct StructSkipDefaultGeneric<T> {
+pub struct StructSkipDefaultGeneric<T> {
     #[serde(skip_deserializing)]
     t: T,
 }

test_suite/tests/test_de_error.rs

@@ -1438,6 +1438,14 @@ fn test_integer_from_float() {
     );
 }
 
+#[test]
+fn test_nan_no_decimal_point() {
+    assert_de_tokens_error::<isize>(
+        &[Token::F32(f32::NAN)],
+        "invalid type: floating point `NaN`, expected isize",
+    );
+}
+
 #[test]
 fn test_unit_struct_from_seq() {
     assert_de_tokens_error::<UnitStruct>(
@@ -1516,7 +1524,6 @@ fn test_systemtime_overflow_struct() {
     );
 }
 
-#[cfg(systemtime_checked_add)]
 #[test]
 fn test_systemtime_overflow() {
     assert_de_tokens_error::<SystemTime>(

test_suite/tests/test_gen.rs

@@ -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,
 

test_suite/tests/test_remote.rs

@@ -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,

test_suite/tests/test_self.rs

@@ -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>,

test_suite/tests/ui/on_unimplemented.rs

@@ -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("");
+}

test_suite/tests/ui/on_unimplemented.stderr

@@ -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`