Release 1.0.191

Render `doc(cfg(...))` on feature gated APIs in docs.rs

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@nightly
       - run: cd test_suite && cargo test --features unstable
 
@@ -27,7 +27,7 @@ jobs:
     runs-on: windows-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@nightly
       - run: cd test_suite && cargo test --features unstable -- --skip ui --exact
 
@@ -40,7 +40,7 @@ jobs:
         rust: [stable, beta]
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
@@ -56,7 +56,7 @@ jobs:
         os: [ubuntu, windows]
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@nightly
       - run: cd serde && cargo build
       - run: cd serde && cargo build --no-default-features
@@ -80,7 +80,7 @@ jobs:
         rust: [1.31.0, 1.34.0]
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
@@ -93,7 +93,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@1.56.0
       - run: cd serde && cargo check --no-default-features
       - run: cd serde && cargo check
@@ -104,7 +104,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@1.36.0
       - run: cd serde && cargo build --no-default-features --features alloc
 
@@ -113,18 +113,32 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@nightly
       - run: cargo generate-lockfile -Z minimal-versions
       - run: cargo check --locked --workspace
 
+  doc:
+    name: Documentation
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    env:
+      RUSTDOCFLAGS: -Dwarnings
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+      - uses: dtolnay/install@cargo-docs-rs
+      - run: cargo docs-rs -p serde
+      - run: cargo docs-rs -p serde_derive
+      - run: cargo docs-rs -p serde_derive_internals
+
   clippy:
     name: Clippy
     runs-on: ubuntu-latest
     if: github.event_name != 'pull_request'
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@clippy
       - run: cd serde && cargo clippy --features rc,unstable -- -Dclippy::all -Dclippy::pedantic
       - run: cd serde_derive && cargo clippy -- -Dclippy::all -Dclippy::pedantic
@@ -137,7 +151,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@miri
       - run: cargo miri setup
       - run: cd serde && cargo miri test --features derive,rc,unstable
@@ -153,6 +167,6 @@ jobs:
     if: github.event_name != 'pull_request'
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/install@cargo-outdated
       - run: cargo outdated --workspace --exit-code 1

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.185" # remember to update html_root_url and serde_derive dependency
+version = "1.0.191"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 build = "build.rs"
 categories = ["encoding", "no-std", "no-std::no-alloc"]
@@ -15,7 +15,7 @@ repository = "https://github.com/serde-rs/serde"
 rust-version = "1.31"
 
 [dependencies]
-serde_derive = { version = "=1.0.185", optional = true, path = "../serde_derive" }
+serde_derive = { version = "1", optional = true, path = "../serde_derive" }
 
 [dev-dependencies]
 serde_derive = { version = "1", path = "../serde_derive" }
@@ -27,9 +27,17 @@ doc-scrape-examples = false
 features = ["derive", "rc"]
 
 [package.metadata.docs.rs]
-features = ["derive"]
+features = ["derive", "rc", "unstable"]
 targets = ["x86_64-unknown-linux-gnu"]
-rustdoc-args = ["--generate-link-to-definition"]
+rustdoc-args = ["--cfg", "doc_cfg", "--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
+# separately with serde's "derive" feature disabled. Every serde_derive release
+# 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 = "=1.0.191", path = "../serde_derive" }
 
 
 ### FEATURES #################################################################

serde/build.rs

@@ -27,11 +27,10 @@ fn main() {
         println!("cargo:rustc-cfg=no_relaxed_trait_bounds");
     }
 
-    // Disabled on Emscripten targets before Rust 1.40 since
-    // Emscripten did not support 128-bit integers until Rust 1.40
-    // (https://github.com/rust-lang/rust/pull/65251)
-    if emscripten && minor < 40 {
-        println!("cargo:rustc-cfg=no_integer128");
+    // f32::copysign and f64::copysign stabilized in Rust 1.35.
+    // https://blog.rust-lang.org/2019/05/23/Rust-1.35.0.html#copy-the-sign-of-a-floating-point-number-onto-another
+    if minor < 35 {
+        println!("cargo:rustc-cfg=no_float_copysign");
     }
 
     // Current minimum supported version of serde_derive crate is Rust 1.56.

serde/src/de/ignored_any.rs

@@ -129,12 +129,10 @@ impl<'de> Visitor<'de> for IgnoredAny {
         Ok(IgnoredAny)
     }
 
-    serde_if_integer128! {
-        #[inline]
-        fn visit_i128<E>(self, x: i128) -> Result<Self::Value, E> {
-            let _ = x;
-            Ok(IgnoredAny)
-        }
+    #[inline]
+    fn visit_i128<E>(self, x: i128) -> Result<Self::Value, E> {
+        let _ = x;
+        Ok(IgnoredAny)
     }
 
     #[inline]
@@ -143,12 +141,10 @@ impl<'de> Visitor<'de> for IgnoredAny {
         Ok(IgnoredAny)
     }
 
-    serde_if_integer128! {
-        #[inline]
-        fn visit_u128<E>(self, x: u128) -> Result<Self::Value, E> {
-            let _ = x;
-            Ok(IgnoredAny)
-        }
+    #[inline]
+    fn visit_u128<E>(self, x: u128) -> Result<Self::Value, E> {
+        let _ = x;
+        Ok(IgnoredAny)
     }
 
     #[inline]

serde/src/de/impls.rs

@@ -39,6 +39,7 @@ impl<'de> Deserialize<'de> for () {
 }
 
 #[cfg(feature = "unstable")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "unstable")))]
 impl<'de> Deserialize<'de> for ! {
     fn deserialize<D>(_deserializer: D) -> Result<Self, D::Error>
     where
@@ -180,6 +181,28 @@ macro_rules! num_as_self {
     };
 }
 
+macro_rules! num_as_copysign_self {
+    ($ty:ident : $visit:ident) => {
+        #[inline]
+        fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
+        where
+            E: Error,
+        {
+            #[cfg(any(no_float_copysign, not(feature = "std")))]
+            {
+                Ok(v as Self::Value)
+            }
+
+            #[cfg(all(not(no_float_copysign), feature = "std"))]
+            {
+                // Preserve sign of NaN. The `as` produces a nondeterministic sign.
+                let sign = if v.is_sign_positive() { 1.0 } else { -1.0 };
+                Ok((v as Self::Value).copysign(sign))
+            }
+        }
+    };
+}
+
 macro_rules! int_to_int {
     ($ty:ident : $visit:ident) => {
         #[inline]
@@ -351,7 +374,7 @@ impl_deserialize_num! {
 impl_deserialize_num! {
     f32, deserialize_f32
     num_self!(f32:visit_f32);
-    num_as_self!(f64:visit_f64);
+    num_as_copysign_self!(f64:visit_f64);
     num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
     num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
 }
@@ -359,69 +382,67 @@ impl_deserialize_num! {
 impl_deserialize_num! {
     f64, deserialize_f64
     num_self!(f64:visit_f64);
-    num_as_self!(f32:visit_f32);
+    num_as_copysign_self!(f32:visit_f32);
     num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
     num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
 }
 
-serde_if_integer128! {
-    macro_rules! num_128 {
-        ($ty:ident : $visit:ident) => {
-            fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
-            where
-                E: Error,
+macro_rules! num_128 {
+    ($ty:ident : $visit:ident) => {
+        fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
+        where
+            E: Error,
+        {
+            if v as i128 >= Self::Value::min_value() as i128
+                && v as u128 <= Self::Value::max_value() as u128
             {
-                if v as i128 >= Self::Value::min_value() as i128
-                    && v as u128 <= Self::Value::max_value() as u128
-                {
-                    Ok(v as Self::Value)
-                } else {
-                    Err(Error::invalid_value(
-                        Unexpected::Other(stringify!($ty)),
-                        &self,
-                    ))
-                }
+                Ok(v as Self::Value)
+            } else {
+                Err(Error::invalid_value(
+                    Unexpected::Other(stringify!($ty)),
+                    &self,
+                ))
             }
-        };
+        }
+    };
 
-        (nonzero $primitive:ident $ty:ident : $visit:ident) => {
-            fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
-            where
-                E: Error,
+    (nonzero $primitive:ident $ty:ident : $visit:ident) => {
+        fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
+        where
+            E: Error,
+        {
+            if v as i128 >= $primitive::min_value() as i128
+                && v as u128 <= $primitive::max_value() as u128
             {
-                if v as i128 >= $primitive::min_value() as i128
-                    && v as u128 <= $primitive::max_value() as u128
-                {
-                    if let Some(nonzero) = Self::Value::new(v as $primitive) {
-                        Ok(nonzero)
-                    } else {
-                        Err(Error::invalid_value(Unexpected::Unsigned(0), &self))
-                    }
+                if let Some(nonzero) = Self::Value::new(v as $primitive) {
+                    Ok(nonzero)
                 } else {
-                    Err(Error::invalid_value(
-                        Unexpected::Other(stringify!($ty)),
-                        &self,
-                    ))
+                    Err(Error::invalid_value(Unexpected::Unsigned(0), &self))
                 }
+            } else {
+                Err(Error::invalid_value(
+                    Unexpected::Other(stringify!($ty)),
+                    &self,
+                ))
             }
-        };
-    }
+        }
+    };
+}
 
-    impl_deserialize_num! {
-        i128, NonZeroI128 cfg(not(no_num_nonzero_signed)), deserialize_i128
-        num_self!(i128:visit_i128);
-        num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
-        num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
-        num_128!(u128:visit_u128);
-    }
+impl_deserialize_num! {
+    i128, NonZeroI128 cfg(not(no_num_nonzero_signed)), deserialize_i128
+    num_self!(i128:visit_i128);
+    num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+    num_128!(u128:visit_u128);
+}
 
-    impl_deserialize_num! {
-        u128, NonZeroU128, deserialize_u128
-        num_self!(u128:visit_u128);
-        num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
-        int_to_uint!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
-        num_128!(i128:visit_i128);
-    }
+impl_deserialize_num! {
+    u128, NonZeroU128, deserialize_u128
+    num_self!(u128:visit_u128);
+    num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+    int_to_uint!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    num_128!(i128:visit_i128);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -576,6 +597,7 @@ 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"))))]
 impl<'de> Deserialize<'de> for String {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -719,6 +741,7 @@ 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"))))]
 impl<'de> Deserialize<'de> for CString {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -730,10 +753,10 @@ impl<'de> Deserialize<'de> for CString {
 
 macro_rules! forwarded_impl {
     (
-        $(#[doc = $doc:tt])*
+        $(#[$attr:meta])*
         ($($id:ident),*), $ty:ty, $func:expr
     ) => {
-        $(#[doc = $doc])*
+        $(#[$attr])*
         impl<'de $(, $id : Deserialize<'de>,)*> Deserialize<'de> for $ty {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
@@ -745,10 +768,15 @@ macro_rules! forwarded_impl {
     }
 }
 
-#[cfg(any(feature = "std", all(not(no_core_cstr), feature = "alloc")))]
-forwarded_impl!((), Box<CStr>, CString::into_boxed_c_str);
+forwarded_impl! {
+    #[cfg(any(feature = "std", all(not(no_core_cstr), feature = "alloc")))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    (), Box<CStr>, CString::into_boxed_c_str
+}
 
-forwarded_impl!((T), Reverse<T>, Reverse);
+forwarded_impl! {
+    (T), Reverse<T>, Reverse
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -854,9 +882,9 @@ impl<'de, T: ?Sized> Deserialize<'de> for PhantomData<T> {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 macro_rules! seq_impl {
     (
+        $(#[$attr:meta])*
         $ty:ident <T $(: $tbound1:ident $(+ $tbound2:ident)*)* $(, $typaram:ident : $bound1:ident $(+ $bound2:ident)*)*>,
         $access:ident,
         $clear:expr,
@@ -864,6 +892,7 @@ macro_rules! seq_impl {
         $reserve:expr,
         $insert:expr
     ) => {
+        $(#[$attr])*
         impl<'de, T $(, $typaram)*> Deserialize<'de> for $ty<T $(, $typaram)*>
         where
             T: Deserialize<'de> $(+ $tbound1 $(+ $tbound2)*)*,
@@ -951,8 +980,9 @@ macro_rules! seq_impl {
 #[cfg(any(feature = "std", feature = "alloc"))]
 fn nop_reserve<T>(_seq: T, _n: usize) {}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 seq_impl!(
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
     BinaryHeap<T: Ord>,
     seq,
     BinaryHeap::clear,
@@ -961,8 +991,9 @@ seq_impl!(
     BinaryHeap::push
 );
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 seq_impl!(
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
     BTreeSet<T: Eq + Ord>,
     seq,
     BTreeSet::clear,
@@ -971,8 +1002,9 @@ seq_impl!(
     BTreeSet::insert
 );
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 seq_impl!(
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
     LinkedList<T>,
     seq,
     LinkedList::clear,
@@ -981,8 +1013,9 @@ seq_impl!(
     LinkedList::push_back
 );
 
-#[cfg(feature = "std")]
 seq_impl!(
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     HashSet<T: Eq + Hash, S: BuildHasher + Default>,
     seq,
     HashSet::clear,
@@ -991,8 +1024,9 @@ seq_impl!(
     HashSet::insert
 );
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 seq_impl!(
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
     VecDeque<T>,
     seq,
     VecDeque::clear,
@@ -1004,6 +1038,7 @@ seq_impl!(
 ////////////////////////////////////////////////////////////////////////////////
 
 #[cfg(any(feature = "std", feature = "alloc"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, T> Deserialize<'de> for Vec<T>
 where
     T: Deserialize<'de>,
@@ -1349,13 +1384,14 @@ tuple_impls! {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 macro_rules! map_impl {
     (
+        $(#[$attr:meta])*
         $ty:ident <K $(: $kbound1:ident $(+ $kbound2:ident)*)*, V $(, $typaram:ident : $bound1:ident $(+ $bound2:ident)*)*>,
         $access:ident,
-        $with_capacity:expr
+        $with_capacity:expr,
     ) => {
+        $(#[$attr])*
         impl<'de, K, V $(, $typaram)*> Deserialize<'de> for $ty<K, V $(, $typaram)*>
         where
             K: Deserialize<'de> $(+ $kbound1 $(+ $kbound2)*)*,
@@ -1404,21 +1440,30 @@ macro_rules! map_impl {
     }
 }
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-map_impl!(BTreeMap<K: Ord, V>, map, BTreeMap::new());
+map_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    BTreeMap<K: Ord, V>,
+    map,
+    BTreeMap::new(),
+}
 
-#[cfg(feature = "std")]
-map_impl!(
+map_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, 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())
-);
+    HashMap::with_capacity_and_hasher(size_hint::cautious::<(K, V)>(map.size_hint()), S::default()),
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(feature = "std")]
 macro_rules! parse_ip_impl {
-    ($expecting:tt $ty:ty; $size:tt) => {
+    (
+        $(#[$attr:meta])*
+        $ty:ty, $expecting:expr, $size:tt
+    ) => {
+        $(#[$attr])*
         impl<'de> Deserialize<'de> for $ty {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
@@ -1547,6 +1592,7 @@ macro_rules! deserialize_enum {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<'de> Deserialize<'de> for net::IpAddr {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -1565,15 +1611,25 @@ impl<'de> Deserialize<'de> for net::IpAddr {
     }
 }
 
-#[cfg(feature = "std")]
-parse_ip_impl!("IPv4 address" net::Ipv4Addr; 4);
+parse_ip_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    net::Ipv4Addr, "IPv4 address", 4
+}
 
-#[cfg(feature = "std")]
-parse_ip_impl!("IPv6 address" net::Ipv6Addr; 16);
+parse_ip_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    net::Ipv6Addr, "IPv6 address", 16
+}
 
-#[cfg(feature = "std")]
 macro_rules! parse_socket_impl {
-    ($expecting:tt $ty:ty, $new:expr) => {
+    (
+        $(#[$attr:meta])*
+        $ty:ty, $expecting:tt,
+        $new:expr,
+    ) => {
+        $(#[$attr])*
         impl<'de> Deserialize<'de> for $ty {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
@@ -1590,6 +1646,7 @@ macro_rules! parse_socket_impl {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<'de> Deserialize<'de> for net::SocketAddr {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -1608,11 +1665,19 @@ impl<'de> Deserialize<'de> for net::SocketAddr {
     }
 }
 
-#[cfg(feature = "std")]
-parse_socket_impl!("IPv4 socket address" net::SocketAddrV4, |(ip, port)| net::SocketAddrV4::new(ip, port));
+parse_socket_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    net::SocketAddrV4, "IPv4 socket address",
+    |(ip, port)| net::SocketAddrV4::new(ip, port),
+}
 
-#[cfg(feature = "std")]
-parse_socket_impl!("IPv6 socket address" net::SocketAddrV6, |(ip, port)| net::SocketAddrV6::new(ip, port, 0, 0));
+parse_socket_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    net::SocketAddrV6, "IPv6 socket address",
+    |(ip, port)| net::SocketAddrV6::new(ip, port, 0, 0),
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -1645,6 +1710,7 @@ impl<'a> Visitor<'a> for PathVisitor {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<'de: 'a, 'a> Deserialize<'de> for &'a Path {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -1699,6 +1765,7 @@ impl<'de> Visitor<'de> for PathBufVisitor {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<'de> Deserialize<'de> for PathBuf {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -1708,8 +1775,11 @@ impl<'de> Deserialize<'de> for PathBuf {
     }
 }
 
-#[cfg(feature = "std")]
-forwarded_impl!((), Box<Path>, PathBuf::into_boxed_path);
+forwarded_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    (), Box<Path>, PathBuf::into_boxed_path
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -1769,6 +1839,7 @@ 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)))))]
 impl<'de> Deserialize<'de> for OsString {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -1780,19 +1851,32 @@ impl<'de> Deserialize<'de> for OsString {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-forwarded_impl!((T), Box<T>, Box::new);
-
-#[cfg(any(feature = "std", feature = "alloc"))]
-forwarded_impl!((T), Box<[T]>, Vec::into_boxed_slice);
-
-#[cfg(any(feature = "std", feature = "alloc"))]
-forwarded_impl!((), Box<str>, String::into_boxed_str);
-
-#[cfg(all(feature = "std", any(unix, windows)))]
-forwarded_impl!((), Box<OsStr>, OsString::into_boxed_os_str);
+forwarded_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, 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"))))]
+    (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"))))]
+    (), 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)))))]
+    (), Box<OsStr>, OsString::into_boxed_os_str
+}
 
 #[cfg(any(feature = "std", feature = "alloc"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, 'a, T: ?Sized> Deserialize<'de> for Cow<'a, T>
 where
     T: ToOwned,
@@ -1814,6 +1898,10 @@ where
 ///
 /// [`"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"))))
+)]
 impl<'de, T: ?Sized> Deserialize<'de> for RcWeak<T>
 where
     T: Deserialize<'de>,
@@ -1832,6 +1920,10 @@ where
 ///
 /// [`"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"))))
+)]
 impl<'de, T: ?Sized> Deserialize<'de> for ArcWeak<T>
 where
     T: Deserialize<'de>,
@@ -1847,13 +1939,12 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 macro_rules! box_forwarded_impl {
     (
-        $(#[doc = $doc:tt])*
+        $(#[$attr:meta])*
         $t:ident
     ) => {
-        $(#[doc = $doc])*
+        $(#[$attr])*
         impl<'de, T: ?Sized> Deserialize<'de> for $t<T>
         where
             Box<T>: Deserialize<'de>,
@@ -1868,7 +1959,6 @@ macro_rules! box_forwarded_impl {
     };
 }
 
-#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1877,10 +1967,11 @@ box_forwarded_impl! {
     /// will end up with a strong count of 1.
     ///
     /// [`"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")))))]
     Rc
 }
 
-#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1889,6 +1980,8 @@ box_forwarded_impl! {
     /// will end up with a strong count of 1.
     ///
     /// [`"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")))))]
     Arc
 }
 
@@ -1906,13 +1999,21 @@ where
     }
 }
 
-forwarded_impl!((T), RefCell<T>, RefCell::new);
+forwarded_impl! {
+    (T), RefCell<T>, RefCell::new
+}
 
-#[cfg(feature = "std")]
-forwarded_impl!((T), Mutex<T>, Mutex::new);
+forwarded_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    (T), Mutex<T>, Mutex::new
+}
 
-#[cfg(feature = "std")]
-forwarded_impl!((T), RwLock<T>, RwLock::new);
+forwarded_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    (T), RwLock<T>, RwLock::new
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -2065,6 +2166,7 @@ impl<'de> Deserialize<'de> for Duration {
 ////////////////////////////////////////////////////////////////////////////////
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<'de> Deserialize<'de> for SystemTime {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -2900,6 +3002,7 @@ 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))))]
             impl<'de> Deserialize<'de> for $ty {
                 fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
                 where

serde/src/de/mod.rs

@@ -118,12 +118,10 @@ use crate::lib::*;
 
 pub mod value;
 
-#[cfg(not(no_integer128))]
 mod format;
 mod ignored_any;
 mod impls;
 pub(crate) mod size_hint;
-mod utf8;
 
 pub use self::ignored_any::IgnoredAny;
 
@@ -950,18 +948,15 @@ pub trait Deserializer<'de>: Sized {
     where
         V: Visitor<'de>;
 
-    serde_if_integer128! {
-        /// Hint that the `Deserialize` type is expecting an `i128` value.
-        ///
-        /// This method is available only on Rust compiler versions >=1.26. The
-        /// default behavior unconditionally returns an error.
-        fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value, Self::Error>
-        where
-            V: Visitor<'de>
-        {
-            let _ = visitor;
-            Err(Error::custom("i128 is not supported"))
-        }
+    /// Hint that the `Deserialize` type is expecting an `i128` value.
+    ///
+    /// The default behavior unconditionally returns an error.
+    fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        let _ = visitor;
+        Err(Error::custom("i128 is not supported"))
     }
 
     /// Hint that the `Deserialize` type is expecting a `u8` value.
@@ -984,18 +979,15 @@ pub trait Deserializer<'de>: Sized {
     where
         V: Visitor<'de>;
 
-    serde_if_integer128! {
-        /// Hint that the `Deserialize` type is expecting an `u128` value.
-        ///
-        /// This method is available only on Rust compiler versions >=1.26. The
-        /// default behavior unconditionally returns an error.
-        fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value, Self::Error>
-        where
-            V: Visitor<'de>
-        {
-            let _ = visitor;
-            Err(Error::custom("u128 is not supported"))
-        }
+    /// Hint that the `Deserialize` type is expecting an `u128` value.
+    ///
+    /// The default behavior unconditionally returns an error.
+    fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        let _ = visitor;
+        Err(Error::custom("u128 is not supported"))
     }
 
     /// Hint that the `Deserialize` type is expecting a `f32` value.
@@ -1367,20 +1359,20 @@ pub trait Visitor<'de>: Sized {
         Err(Error::invalid_type(Unexpected::Signed(v), &self))
     }
 
-    serde_if_integer128! {
-        /// The input contains a `i128`.
-        ///
-        /// This method is available only on Rust compiler versions >=1.26. The
-        /// default implementation fails with a type error.
-        fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E>
-        where
-            E: Error,
-        {
-            let mut buf = [0u8; 58];
-            let mut writer = format::Buf::new(&mut buf);
-            fmt::Write::write_fmt(&mut writer, format_args!("integer `{}` as i128", v)).unwrap();
-            Err(Error::invalid_type(Unexpected::Other(writer.as_str()), &self))
-        }
+    /// The input contains a `i128`.
+    ///
+    /// The default implementation fails with a type error.
+    fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E>
+    where
+        E: Error,
+    {
+        let mut buf = [0u8; 58];
+        let mut writer = format::Buf::new(&mut buf);
+        fmt::Write::write_fmt(&mut writer, format_args!("integer `{}` as i128", v)).unwrap();
+        Err(Error::invalid_type(
+            Unexpected::Other(writer.as_str()),
+            &self,
+        ))
     }
 
     /// The input contains a `u8`.
@@ -1429,20 +1421,20 @@ pub trait Visitor<'de>: Sized {
         Err(Error::invalid_type(Unexpected::Unsigned(v), &self))
     }
 
-    serde_if_integer128! {
-        /// The input contains a `u128`.
-        ///
-        /// This method is available only on Rust compiler versions >=1.26. The
-        /// default implementation fails with a type error.
-        fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E>
-        where
-            E: Error,
-        {
-            let mut buf = [0u8; 57];
-            let mut writer = format::Buf::new(&mut buf);
-            fmt::Write::write_fmt(&mut writer, format_args!("integer `{}` as u128", v)).unwrap();
-            Err(Error::invalid_type(Unexpected::Other(writer.as_str()), &self))
-        }
+    /// The input contains a `u128`.
+    ///
+    /// The default implementation fails with a type error.
+    fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E>
+    where
+        E: Error,
+    {
+        let mut buf = [0u8; 57];
+        let mut writer = format::Buf::new(&mut buf);
+        fmt::Write::write_fmt(&mut writer, format_args!("integer `{}` as u128", v)).unwrap();
+        Err(Error::invalid_type(
+            Unexpected::Other(writer.as_str()),
+            &self,
+        ))
     }
 
     /// The input contains an `f32`.
@@ -1478,7 +1470,7 @@ pub trait Visitor<'de>: Sized {
     where
         E: Error,
     {
-        self.visit_str(utf8::encode(v).as_str())
+        self.visit_str(v.encode_utf8(&mut [0u8; 4]))
     }
 
     /// The input contains a string. The lifetime of the string is ephemeral and
@@ -1533,6 +1525,7 @@ pub trait Visitor<'de>: Sized {
     /// `String`.
     #[inline]
     #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
     fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
     where
         E: Error,
@@ -1555,7 +1548,6 @@ pub trait Visitor<'de>: Sized {
     where
         E: Error,
     {
-        let _ = v;
         Err(Error::invalid_type(Unexpected::Bytes(v), &self))
     }
 
@@ -1592,6 +1584,7 @@ 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"))))]
     fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
     where
         E: Error,

serde/src/de/utf8.rs

@@ -1,46 +0,0 @@
-use crate::lib::*;
-
-const TAG_CONT: u8 = 0b1000_0000;
-const TAG_TWO_B: u8 = 0b1100_0000;
-const TAG_THREE_B: u8 = 0b1110_0000;
-const TAG_FOUR_B: u8 = 0b1111_0000;
-const MAX_ONE_B: u32 = 0x80;
-const MAX_TWO_B: u32 = 0x800;
-const MAX_THREE_B: u32 = 0x10000;
-
-#[inline]
-pub fn encode(c: char) -> Encode {
-    let code = c as u32;
-    let mut buf = [0; 4];
-    let pos = if code < MAX_ONE_B {
-        buf[3] = code as u8;
-        3
-    } else if code < MAX_TWO_B {
-        buf[2] = (code >> 6 & 0x1F) as u8 | TAG_TWO_B;
-        buf[3] = (code & 0x3F) as u8 | TAG_CONT;
-        2
-    } else if code < MAX_THREE_B {
-        buf[1] = (code >> 12 & 0x0F) as u8 | TAG_THREE_B;
-        buf[2] = (code >> 6 & 0x3F) as u8 | TAG_CONT;
-        buf[3] = (code & 0x3F) as u8 | TAG_CONT;
-        1
-    } else {
-        buf[0] = (code >> 18 & 0x07) as u8 | TAG_FOUR_B;
-        buf[1] = (code >> 12 & 0x3F) as u8 | TAG_CONT;
-        buf[2] = (code >> 6 & 0x3F) as u8 | TAG_CONT;
-        buf[3] = (code & 0x3F) as u8 | TAG_CONT;
-        0
-    };
-    Encode { buf, pos }
-}
-
-pub struct Encode {
-    buf: [u8; 4],
-    pos: usize,
-}
-
-impl Encode {
-    pub fn as_str(&self) -> &str {
-        str::from_utf8(&self.buf[self.pos..]).unwrap()
-    }
-}

serde/src/de/value.rs

@@ -112,6 +112,7 @@ impl Debug for Error {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl error::Error for Error {
     fn description(&self) -> &str {
         &self.err
@@ -184,12 +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")))]
 pub struct NeverDeserializer<E> {
     never: !,
     marker: PhantomData<E>,
 }
 
 #[cfg(feature = "unstable")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "unstable")))]
 impl<'de, E> IntoDeserializer<'de, E> for !
 where
     E: de::Error,
@@ -292,20 +295,17 @@ primitive_deserializer!(i8, "an `i8`.", I8Deserializer, visit_i8);
 primitive_deserializer!(i16, "an `i16`.", I16Deserializer, visit_i16);
 primitive_deserializer!(i32, "an `i32`.", I32Deserializer, visit_i32);
 primitive_deserializer!(i64, "an `i64`.", I64Deserializer, visit_i64);
+primitive_deserializer!(i128, "an `i128`.", I128Deserializer, visit_i128);
 primitive_deserializer!(isize, "an `isize`.", IsizeDeserializer, visit_i64 as i64);
 primitive_deserializer!(u8, "a `u8`.", U8Deserializer, visit_u8);
 primitive_deserializer!(u16, "a `u16`.", U16Deserializer, visit_u16);
 primitive_deserializer!(u64, "a `u64`.", U64Deserializer, visit_u64);
+primitive_deserializer!(u128, "a `u128`.", U128Deserializer, visit_u128);
 primitive_deserializer!(usize, "a `usize`.", UsizeDeserializer, visit_u64 as u64);
 primitive_deserializer!(f32, "an `f32`.", F32Deserializer, visit_f32);
 primitive_deserializer!(f64, "an `f64`.", F64Deserializer, visit_f64);
 primitive_deserializer!(char, "a `char`.", CharDeserializer, visit_char);
 
-serde_if_integer128! {
-    primitive_deserializer!(i128, "an `i128`.", I128Deserializer, visit_i128);
-    primitive_deserializer!(u128, "a `u128`.", U128Deserializer, visit_u128);
-}
-
 /// A deserializer holding a `u32`.
 pub struct U32Deserializer<E> {
     value: u32,
@@ -565,6 +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"))))]
 pub struct StringDeserializer<E> {
     value: String,
     marker: PhantomData<E>,
@@ -581,6 +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"))))]
 impl<'de, E> IntoDeserializer<'de, E> for String
 where
     E: de::Error,
@@ -668,6 +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"))))]
 pub struct CowStrDeserializer<'a, E> {
     value: Cow<'a, str>,
     marker: PhantomData<E>,
@@ -684,6 +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"))))]
 impl<'de, 'a, E> IntoDeserializer<'de, E> for Cow<'a, str>
 where
     E: de::Error,
@@ -1002,6 +1006,7 @@ where
 ////////////////////////////////////////////////////////////////////////////////
 
 #[cfg(any(feature = "std", feature = "alloc"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, T, E> IntoDeserializer<'de, E> for Vec<T>
 where
     T: IntoDeserializer<'de, E>,
@@ -1015,6 +1020,7 @@ where
 }
 
 #[cfg(any(feature = "std", feature = "alloc"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl<'de, T, E> IntoDeserializer<'de, E> for BTreeSet<T>
 where
     T: IntoDeserializer<'de, E> + Eq + Ord,
@@ -1028,6 +1034,7 @@ where
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<'de, T, S, E> IntoDeserializer<'de, E> for HashSet<T, S>
 where
     T: IntoDeserializer<'de, E> + Eq + Hash,
@@ -1414,6 +1421,7 @@ impl Expected for ExpectedInMap {
 ////////////////////////////////////////////////////////////////////////////////
 
 #[cfg(any(feature = "std", feature = "alloc"))]
+#[cfg_attr(doc_cfg, 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,
@@ -1428,6 +1436,7 @@ where
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, 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/integer128.rs

@@ -1,82 +1,9 @@
-/// Conditional compilation depending on whether Serde is built with support for
-/// 128-bit integers.
-///
-/// Data formats that wish to support Rust compiler versions older than 1.26
-/// (or targets that lack 128-bit integers) may place the i128 / u128 methods
-/// of their Serializer and Deserializer behind this macro.
-///
-/// Data formats that require a minimum Rust compiler version of at least 1.26,
-/// or do not target platforms that lack 128-bit integers, do not need to
-/// bother with this macro and may assume support for 128-bit integers.
-///
-/// ```edition2021
-/// # use serde::__private::doc::Error;
-/// #
-/// # struct MySerializer;
-/// #
-/// use serde::{serde_if_integer128, Serializer};
-///
-/// impl Serializer for MySerializer {
-///     type Ok = ();
-///     type Error = Error;
-///
-///     fn serialize_i64(self, v: i64) -> Result<Self::Ok, Self::Error> {
-///         /* ... */
-/// #         unimplemented!()
-///     }
-///
-///     /* ... */
-///
-///     serde_if_integer128! {
-///         fn serialize_i128(self, v: i128) -> Result<Self::Ok, Self::Error> {
-///             /* ... */
-/// #             unimplemented!()
-///         }
-///
-///         fn serialize_u128(self, v: u128) -> Result<Self::Ok, Self::Error> {
-///             /* ... */
-/// #             unimplemented!()
-///         }
-///     }
-/// #
-/// #     serde::__serialize_unimplemented! {
-/// #         bool i8 i16 i32 u8 u16 u32 u64 f32 f64 char str bytes none some
-/// #         unit unit_struct unit_variant newtype_struct newtype_variant seq
-/// #         tuple tuple_struct tuple_variant map struct struct_variant
-/// #     }
-/// }
-/// ```
-///
-/// When Serde is built with support for 128-bit integers, this macro expands
-/// transparently into just the input tokens.
-///
-/// ```edition2021
-/// macro_rules! serde_if_integer128 {
-///     ($($tt:tt)*) => {
-///         $($tt)*
-///     };
-/// }
-/// ```
-///
-/// When built without support for 128-bit integers, this macro expands to
-/// nothing.
-///
-/// ```edition2021
-/// macro_rules! serde_if_integer128 {
-///     ($($tt:tt)*) => {};
-/// }
-/// ```
-#[cfg(not(no_integer128))]
+// No longer used. Old versions of serde used this macro for supporting targets
+// that did not yet have 128-bit integer support.
 #[macro_export]
+#[doc(hidden)]
 macro_rules! serde_if_integer128 {
     ($($tt:tt)*) => {
         $($tt)*
     };
 }
-
-#[cfg(no_integer128)]
-#[macro_export]
-#[doc(hidden)]
-macro_rules! serde_if_integer128 {
-    ($($tt:tt)*) => {};
-}

serde/src/lib.rs

@@ -63,6 +63,7 @@
 //!   and from DynamoDB.
 //! - [Hjson], a syntax extension to JSON designed around human reading and
 //!   editing. *(deserialization only)*
+//! - [CSV], Comma-separated values is a tabular text file format.
 //!
 //! [JSON]: https://github.com/serde-rs/json
 //! [Postcard]: https://github.com/jamesmunns/postcard
@@ -89,13 +90,16 @@
 //! [DynamoDB Items]: https://docs.rs/serde_dynamo
 //! [rusoto_dynamodb]: https://docs.rs/rusoto_dynamodb
 //! [Hjson]: https://github.com/Canop/deser-hjson
+//! [CSV]: https://docs.rs/csv
 
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.185")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.191")]
 // 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))]
 // Unstable functionality only if the user asks for it. For tracking and
 // discussion of these features please refer to this issue:
 //
@@ -166,11 +170,14 @@ mod lib {
         pub use std::*;
     }
 
-    pub use self::core::{cmp, iter, mem, num, ptr, slice, str};
     pub use self::core::{f32, f64};
     pub use self::core::{i16, i32, i64, i8, isize};
+    pub use self::core::{iter, num, ptr, str};
     pub use self::core::{u16, u32, u64, u8, usize};
 
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    pub use self::core::{cmp, mem, slice};
+
     pub use self::core::cell::{Cell, RefCell};
     pub use self::core::clone::{self, Clone};
     pub use self::core::cmp::Reverse;
@@ -319,6 +326,7 @@ 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")))]
 pub use serde_derive::{Deserialize, Serialize};
 
 #[cfg(all(not(no_serde_derive), any(feature = "std", feature = "alloc")))]

serde/src/macros.rs

@@ -154,9 +154,7 @@ macro_rules! forward_to_deserialize_any_helper {
         forward_to_deserialize_any_method!{deserialize_i64<$l, $v>()}
     };
     (i128<$l:tt, $v:ident>) => {
-        serde_if_integer128! {
-            forward_to_deserialize_any_method!{deserialize_i128<$l, $v>()}
-        }
+        forward_to_deserialize_any_method!{deserialize_i128<$l, $v>()}
     };
     (u8<$l:tt, $v:ident>) => {
         forward_to_deserialize_any_method!{deserialize_u8<$l, $v>()}
@@ -171,9 +169,7 @@ macro_rules! forward_to_deserialize_any_helper {
         forward_to_deserialize_any_method!{deserialize_u64<$l, $v>()}
     };
     (u128<$l:tt, $v:ident>) => {
-        serde_if_integer128! {
-            forward_to_deserialize_any_method!{deserialize_u128<$l, $v>()}
-        }
+        forward_to_deserialize_any_method!{deserialize_u128<$l, $v>()}
     };
     (f32<$l:tt, $v:ident>) => {
         forward_to_deserialize_any_method!{deserialize_f32<$l, $v>()}

serde/src/ser/fmt.rs

@@ -52,10 +52,12 @@ impl<'a, 'b> Serializer for &'a mut fmt::Formatter<'b> {
         serialize_i16: i16,
         serialize_i32: i32,
         serialize_i64: i64,
+        serialize_i128: i128,
         serialize_u8: u8,
         serialize_u16: u16,
         serialize_u32: u32,
         serialize_u64: u64,
+        serialize_u128: u128,
         serialize_f32: f32,
         serialize_f64: f64,
         serialize_char: char,
@@ -63,13 +65,6 @@ impl<'a, 'b> Serializer for &'a mut fmt::Formatter<'b> {
         serialize_unit_struct: &'static str,
     }
 
-    serde_if_integer128! {
-        fmt_primitives! {
-            serialize_i128: i128,
-            serialize_u128: u128,
-        }
-    }
-
     fn serialize_unit_variant(
         self,
         _name: &'static str,

serde/src/ser/impls.rs

@@ -24,20 +24,17 @@ primitive_impl!(i8, serialize_i8);
 primitive_impl!(i16, serialize_i16);
 primitive_impl!(i32, serialize_i32);
 primitive_impl!(i64, serialize_i64);
+primitive_impl!(i128, serialize_i128);
 primitive_impl!(usize, serialize_u64 as u64);
 primitive_impl!(u8, serialize_u8);
 primitive_impl!(u16, serialize_u16);
 primitive_impl!(u32, serialize_u32);
 primitive_impl!(u64, serialize_u64);
+primitive_impl!(u128, serialize_u128);
 primitive_impl!(f32, serialize_f32);
 primitive_impl!(f64, serialize_f64);
 primitive_impl!(char, serialize_char);
 
-serde_if_integer128! {
-    primitive_impl!(i128, serialize_i128);
-    primitive_impl!(u128, serialize_u128);
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 
 impl Serialize for str {
@@ -51,6 +48,7 @@ impl Serialize for str {
 }
 
 #[cfg(any(feature = "std", feature = "alloc"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
 impl Serialize for String {
     #[inline]
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -73,6 +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")))]
 impl Serialize for CStr {
     #[inline]
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -84,6 +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"))))]
 impl Serialize for CString {
     #[inline]
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -182,9 +182,13 @@ where
     }
 }
 
-#[cfg(all(any(feature = "std", feature = "alloc"), not(no_relaxed_trait_bounds)))]
+#[cfg(not(no_relaxed_trait_bounds))]
 macro_rules! seq_impl {
-    ($ty:ident <T $(: $tbound1:ident $(+ $tbound2:ident)*)* $(, $typaram:ident : $bound:ident)*>) => {
+    (
+        $(#[$attr:meta])*
+        $ty:ident <T $(: $tbound1:ident $(+ $tbound2:ident)*)* $(, $typaram:ident : $bound:ident)*>
+    ) => {
+        $(#[$attr])*
         impl<T $(, $typaram)*> Serialize for $ty<T $(, $typaram)*>
         where
             T: Serialize,
@@ -200,9 +204,13 @@ macro_rules! seq_impl {
     }
 }
 
-#[cfg(all(any(feature = "std", feature = "alloc"), no_relaxed_trait_bounds))]
+#[cfg(no_relaxed_trait_bounds)]
 macro_rules! seq_impl {
-    ($ty:ident <T $(: $tbound1:ident $(+ $tbound2:ident)*)* $(, $typaram:ident : $bound:ident)*>) => {
+    (
+        $(#[$attr:meta])*
+        $ty:ident <T $(: $tbound1:ident $(+ $tbound2:ident)*)* $(, $typaram:ident : $bound:ident)*>
+    ) => {
+        $(#[$attr])*
         impl<T $(, $typaram)*> Serialize for $ty<T $(, $typaram)*>
         where
             T: Serialize $(+ $tbound1 $(+ $tbound2)*)*,
@@ -219,23 +227,41 @@ macro_rules! seq_impl {
     }
 }
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-seq_impl!(BinaryHeap<T: Ord>);
+seq_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    BinaryHeap<T: Ord>
+}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-seq_impl!(BTreeSet<T: Ord>);
+seq_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    BTreeSet<T: Ord>
+}
 
-#[cfg(feature = "std")]
-seq_impl!(HashSet<T: Eq + Hash, H: BuildHasher>);
+seq_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    HashSet<T: Eq + Hash, H: BuildHasher>
+}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-seq_impl!(LinkedList<T>);
+seq_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    LinkedList<T>
+}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-seq_impl!(Vec<T>);
+seq_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    Vec<T>
+}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-seq_impl!(VecDeque<T>);
+seq_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    VecDeque<T>
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -342,6 +368,7 @@ impl Serialize for () {
 }
 
 #[cfg(feature = "unstable")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "unstable")))]
 impl Serialize for ! {
     fn serialize<S>(&self, _serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -397,9 +424,13 @@ tuple_impls! {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(all(any(feature = "std", feature = "alloc"), not(no_relaxed_trait_bounds)))]
+#[cfg(not(no_relaxed_trait_bounds))]
 macro_rules! map_impl {
-    ($ty:ident <K $(: $kbound1:ident $(+ $kbound2:ident)*)*, V $(, $typaram:ident : $bound:ident)*>) => {
+    (
+        $(#[$attr:meta])*
+        $ty:ident <K $(: $kbound1:ident $(+ $kbound2:ident)*)*, V $(, $typaram:ident : $bound:ident)*>
+    ) => {
+        $(#[$attr])*
         impl<K, V $(, $typaram)*> Serialize for $ty<K, V $(, $typaram)*>
         where
             K: Serialize,
@@ -416,9 +447,13 @@ macro_rules! map_impl {
     }
 }
 
-#[cfg(all(any(feature = "std", feature = "alloc"), no_relaxed_trait_bounds))]
+#[cfg(no_relaxed_trait_bounds)]
 macro_rules! map_impl {
-    ($ty:ident <K $(: $kbound1:ident $(+ $kbound2:ident)*)*, V $(, $typaram:ident : $bound:ident)*>) => {
+    (
+        $(#[$attr:meta])*
+        $ty:ident <K $(: $kbound1:ident $(+ $kbound2:ident)*)*, V $(, $typaram:ident : $bound:ident)*>
+    ) => {
+        $(#[$attr])*
         impl<K, V $(, $typaram)*> Serialize for $ty<K, V $(, $typaram)*>
         where
             K: Serialize $(+ $kbound1 $(+ $kbound2)*)*,
@@ -436,20 +471,26 @@ macro_rules! map_impl {
     }
 }
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-map_impl!(BTreeMap<K: Ord, V>);
+map_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    BTreeMap<K: Ord, V>
+}
 
-#[cfg(feature = "std")]
-map_impl!(HashMap<K: Eq + Hash, V, H: BuildHasher>);
+map_impl! {
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    HashMap<K: Eq + Hash, V, H: BuildHasher>
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
 macro_rules! deref_impl {
     (
-        $(#[doc = $doc:tt])*
+        $(#[$attr:meta])*
         <$($desc:tt)+
     ) => {
-        $(#[doc = $doc])*
+        $(#[$attr])*
         impl <$($desc)+ {
             #[inline]
             fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -462,13 +503,20 @@ macro_rules! deref_impl {
     };
 }
 
-deref_impl!(<'a, T: ?Sized> Serialize for &'a T where T: Serialize);
-deref_impl!(<'a, T: ?Sized> Serialize for &'a mut T where T: Serialize);
+deref_impl! {
+    <'a, T: ?Sized> Serialize for &'a T where T: Serialize
+}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-deref_impl!(<T: ?Sized> Serialize for Box<T> where T: Serialize);
+deref_impl! {
+    <'a, T: ?Sized> Serialize for &'a mut T where T: Serialize
+}
+
+deref_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    <T: ?Sized> Serialize for Box<T> where T: Serialize
+}
 
-#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 deref_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -478,10 +526,11 @@ deref_impl! {
     /// repeated data.
     ///
     /// [`"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")))))]
     <T: ?Sized> Serialize for Rc<T> where T: Serialize
 }
 
-#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 deref_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -491,11 +540,16 @@ deref_impl! {
     /// repeated data.
     ///
     /// [`"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")))))]
     <T: ?Sized> Serialize for Arc<T> where T: Serialize
 }
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-deref_impl!(<'a, T: ?Sized> Serialize for Cow<'a, T> where T: Serialize + ToOwned);
+deref_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
+    <'a, T: ?Sized> Serialize for Cow<'a, T> where T: Serialize + ToOwned
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -503,6 +557,10 @@ deref_impl!(<'a, T: ?Sized> Serialize for Cow<'a, T> where T: Serialize + ToOwne
 ///
 /// [`"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"))))
+)]
 impl<T: ?Sized> Serialize for RcWeak<T>
 where
     T: Serialize,
@@ -519,6 +577,10 @@ where
 ///
 /// [`"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"))))
+)]
 impl<T: ?Sized> Serialize for ArcWeak<T>
 where
     T: Serialize,
@@ -553,6 +615,7 @@ nonzero_integers! {
     NonZeroU16,
     NonZeroU32,
     NonZeroU64,
+    NonZeroU128,
     NonZeroUsize,
 }
 
@@ -562,22 +625,10 @@ nonzero_integers! {
     NonZeroI16,
     NonZeroI32,
     NonZeroI64,
+    NonZeroI128,
     NonZeroIsize,
 }
 
-// Currently 128-bit integers do not work on Emscripten targets so we need an
-// additional `#[cfg]`
-serde_if_integer128! {
-    nonzero_integers! {
-        NonZeroU128,
-    }
-
-    #[cfg(not(no_num_nonzero_signed))]
-    nonzero_integers! {
-        NonZeroI128,
-    }
-}
-
 impl<T> Serialize for Cell<T>
 where
     T: Serialize + Copy,
@@ -606,6 +657,7 @@ where
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<T: ?Sized> Serialize for Mutex<T>
 where
     T: Serialize,
@@ -622,6 +674,7 @@ where
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<T: ?Sized> Serialize for RwLock<T>
 where
     T: Serialize,
@@ -675,6 +728,7 @@ impl Serialize for Duration {
 ////////////////////////////////////////////////////////////////////////////////
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for SystemTime {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -719,6 +773,7 @@ macro_rules! serialize_display_bounded_length {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for net::IpAddr {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -789,6 +844,7 @@ fn test_format_u8() {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for net::Ipv4Addr {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -813,6 +869,7 @@ impl Serialize for net::Ipv4Addr {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for net::Ipv6Addr {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -829,6 +886,7 @@ impl Serialize for net::Ipv6Addr {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for net::SocketAddr {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -853,6 +911,7 @@ impl Serialize for net::SocketAddr {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for net::SocketAddrV4 {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -869,6 +928,7 @@ impl Serialize for net::SocketAddrV4 {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for net::SocketAddrV6 {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -890,6 +950,7 @@ impl Serialize for net::SocketAddrV6 {
 ////////////////////////////////////////////////////////////////////////////////
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for Path {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -903,6 +964,7 @@ impl Serialize for Path {
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl Serialize for PathBuf {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -913,6 +975,7 @@ impl Serialize for PathBuf {
 }
 
 #[cfg(all(feature = "std", any(unix, windows)))]
+#[cfg_attr(doc_cfg, 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>
@@ -935,6 +998,7 @@ impl Serialize for OsStr {
 }
 
 #[cfg(all(feature = "std", any(unix, windows)))]
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "std", any(unix, windows)))))]
 impl Serialize for OsString {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -979,6 +1043,7 @@ 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))))]
             impl Serialize for $ty {
                 fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
                 where

serde/src/ser/mod.rs

@@ -488,30 +488,27 @@ pub trait Serializer: Sized {
     /// ```
     fn serialize_i64(self, v: i64) -> Result<Self::Ok, Self::Error>;
 
-    serde_if_integer128! {
-        /// Serialize an `i128` value.
-        ///
-        /// ```edition2021
-        /// # use serde::Serializer;
-        /// #
-        /// # serde::__private_serialize!();
-        /// #
-        /// impl Serialize for i128 {
-        ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-        ///     where
-        ///         S: Serializer,
-        ///     {
-        ///         serializer.serialize_i128(*self)
-        ///     }
-        /// }
-        /// ```
-        ///
-        /// This method is available only on Rust compiler versions >=1.26. The
-        /// default behavior unconditionally returns an error.
-        fn serialize_i128(self, v: i128) -> Result<Self::Ok, Self::Error> {
-            let _ = v;
-            Err(Error::custom("i128 is not supported"))
-        }
+    /// Serialize an `i128` value.
+    ///
+    /// ```edition2021
+    /// # use serde::Serializer;
+    /// #
+    /// # serde::__private_serialize!();
+    /// #
+    /// impl Serialize for i128 {
+    ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    ///     where
+    ///         S: Serializer,
+    ///     {
+    ///         serializer.serialize_i128(*self)
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// The default behavior unconditionally returns an error.
+    fn serialize_i128(self, v: i128) -> Result<Self::Ok, Self::Error> {
+        let _ = v;
+        Err(Error::custom("i128 is not supported"))
     }
 
     /// Serialize a `u8` value.
@@ -598,30 +595,27 @@ pub trait Serializer: Sized {
     /// ```
     fn serialize_u64(self, v: u64) -> Result<Self::Ok, Self::Error>;
 
-    serde_if_integer128! {
-        /// Serialize a `u128` value.
-        ///
-        /// ```edition2021
-        /// # use serde::Serializer;
-        /// #
-        /// # serde::__private_serialize!();
-        /// #
-        /// impl Serialize for u128 {
-        ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-        ///     where
-        ///         S: Serializer,
-        ///     {
-        ///         serializer.serialize_u128(*self)
-        ///     }
-        /// }
-        /// ```
-        ///
-        /// This method is available only on Rust compiler versions >=1.26. The
-        /// default behavior unconditionally returns an error.
-        fn serialize_u128(self, v: u128) -> Result<Self::Ok, Self::Error> {
-            let _ = v;
-            Err(Error::custom("u128 is not supported"))
-        }
+    /// Serialize a `u128` value.
+    ///
+    /// ```edition2021
+    /// # use serde::Serializer;
+    /// #
+    /// # serde::__private_serialize!();
+    /// #
+    /// impl Serialize for u128 {
+    ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    ///     where
+    ///         S: Serializer,
+    ///     {
+    ///         serializer.serialize_u128(*self)
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// The default behavior unconditionally returns an error.
+    fn serialize_u128(self, v: u128) -> Result<Self::Ok, Self::Error> {
+        let _ = v;
+        Err(Error::custom("u128 is not supported"))
     }
 
     /// Serialize an `f32` value.

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.185" # remember to update html_root_url
+version = "1.0.191"
 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)]"

serde_derive/src/de.rs

@@ -1737,7 +1737,6 @@ fn deserialize_untagged_enum_after(
                 quote!(__deserializer),
             ))
         });
-    let attempts = first_attempt.into_iter().chain(attempts);
     // TODO this message could be better by saving the errors from the failed
     // attempts. The heuristic used by TOML was to count the number of fields
     // processed before an error, and use the error that happened after the
@@ -1750,10 +1749,23 @@ fn deserialize_untagged_enum_after(
     );
     let fallthrough_msg = cattrs.expecting().unwrap_or(&fallthrough_msg);
 
+    // Ignore any error associated with non-untagged deserialization so that we
+    // can fall through to the untagged variants. This may be infallible so we
+    // need to provide the error type.
+    let first_attempt = first_attempt.map(|expr| {
+        quote! {
+            if let _serde::__private::Result::<_, __D::Error>::Ok(__ok) = (|| #expr)() {
+                return _serde::__private::Ok(__ok);
+            }
+        }
+    });
+
     quote_block! {
         let __content = <_serde::__private::de::Content as _serde::Deserialize>::deserialize(__deserializer)?;
         let __deserializer = _serde::__private::de::ContentRefDeserializer::<__D::Error>::new(&__content);
 
+        #first_attempt
+
         #(
             if let _serde::__private::Ok(__ok) = #attempts {
                 return _serde::__private::Ok(__ok);
@@ -1828,7 +1840,7 @@ fn deserialize_internally_tagged_variant(
             let this_value = &params.this_value;
             let type_name = params.type_name();
             let variant_name = variant.ident.to_string();
-            let default = variant.fields.get(0).map(|field| {
+            let default = variant.fields.first().map(|field| {
                 let default = Expr(expr_is_missing(field, cattrs));
                 quote!((#default))
             });
@@ -1873,7 +1885,7 @@ fn deserialize_untagged_variant(
             let this_value = &params.this_value;
             let type_name = params.type_name();
             let variant_name = variant.ident.to_string();
-            let default = variant.fields.get(0).map(|field| {
+            let default = variant.fields.first().map(|field| {
                 let default = Expr(expr_is_missing(field, cattrs));
                 quote!((#default))
             });

serde_derive/src/lib.rs

@@ -13,7 +13,7 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.185")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.191")]
 // Ignored clippy lints
 #![allow(
     // clippy false positive: https://github.com/rust-lang/rust-clippy/issues/7054

serde_derive/src/ser.rs

@@ -710,7 +710,7 @@ fn serialize_adjacently_tagged_variant(
     });
 
     let fields_ty = variant.fields.iter().map(|f| &f.ty);
-    let fields_ident: &Vec<_> = &match variant.style {
+    let fields_ident: &[_] = &match variant.style {
         Style::Unit => {
             if variant.attrs.serialize_with().is_some() {
                 vec![]

serde_derive_internals/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive_internals"
-version = "0.28.0" # remember to update html_root_url
+version = "0.29.0"
 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/lib.rs

@@ -1,4 +1,4 @@
-#![doc(html_root_url = "https://docs.rs/serde_derive_internals/0.28.0")]
+#![doc(html_root_url = "https://docs.rs/serde_derive_internals/0.29.0")]
 // Ignored clippy lints
 #![allow(
     clippy::cognitive_complexity,

test_suite/tests/test_annotations.rs

@@ -2380,6 +2380,68 @@ fn test_partially_untagged_enum_desugared() {
     );
 }
 
+#[test]
+fn test_partially_untagged_internally_tagged_enum() {
+    #[derive(Serialize, Deserialize, PartialEq, Debug)]
+    #[serde(tag = "t")]
+    enum Data {
+        A,
+        B,
+        #[serde(untagged)]
+        Var(u32),
+    }
+
+    let data = Data::A;
+
+    assert_de_tokens(
+        &data,
+        &[
+            Token::Map { len: None },
+            Token::Str("t"),
+            Token::Str("A"),
+            Token::MapEnd,
+        ],
+    );
+
+    let data = Data::Var(42);
+
+    assert_de_tokens(&data, &[Token::U32(42)]);
+
+    // TODO test error output
+}
+
+#[test]
+fn test_partially_untagged_adjacently_tagged_enum() {
+    #[derive(Serialize, Deserialize, PartialEq, Debug)]
+    #[serde(tag = "t", content = "c")]
+    enum Data {
+        A(u32),
+        B,
+        #[serde(untagged)]
+        Var(u32),
+    }
+
+    let data = Data::A(7);
+
+    assert_de_tokens(
+        &data,
+        &[
+            Token::Map { len: None },
+            Token::Str("t"),
+            Token::Str("A"),
+            Token::Str("c"),
+            Token::U32(7),
+            Token::MapEnd,
+        ],
+    );
+
+    let data = Data::Var(42);
+
+    assert_de_tokens(&data, &[Token::U32(42)]);
+
+    // TODO test error output
+}
+
 #[test]
 fn test_flatten_option() {
     #[derive(Serialize, Deserialize, PartialEq, Debug)]
@@ -2719,7 +2781,7 @@ fn test_expecting_message_externally_tagged_enum() {
     // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
     assert_de_tokens_error::<Enum>(
         &[Token::Enum { name: "Enum" }, Token::Unit],
-        r#"invalid type: unit value, expected variant identifier"#,
+        "invalid type: unit value, expected variant identifier",
     );
 }
 
@@ -2740,7 +2802,7 @@ fn test_expecting_message_internally_tagged_enum() {
     // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
     assert_de_tokens_error::<Enum>(
         &[Token::Map { len: None }, Token::Str("tag"), Token::Unit],
-        r#"invalid type: unit value, expected variant identifier"#,
+        "invalid type: unit value, expected variant identifier",
     );
 }
 
@@ -2766,7 +2828,7 @@ fn test_expecting_message_adjacently_tagged_enum() {
     // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
     assert_de_tokens_error::<Enum>(
         &[Token::Map { len: None }, Token::Str("tag"), Token::Unit],
-        r#"invalid type: unit value, expected variant of enum Enum"#,
+        "invalid type: unit value, expected variant of enum Enum",
     );
 }
 
@@ -2779,7 +2841,7 @@ fn test_expecting_message_untagged_tagged_enum() {
         Untagged,
     }
 
-    assert_de_tokens_error::<Enum>(&[Token::Str("Untagged")], r#"something strange..."#);
+    assert_de_tokens_error::<Enum>(&[Token::Str("Untagged")], "something strange...");
 }
 
 #[test]
@@ -2800,7 +2862,7 @@ fn test_expecting_message_identifier_enum() {
 
     assert_de_tokens_error::<FieldEnum>(
         &[Token::Unit],
-        r#"invalid type: unit value, expected something strange..."#,
+        "invalid type: unit value, expected something strange...",
     );
 
     assert_de_tokens_error::<FieldEnum>(
@@ -2809,12 +2871,12 @@ fn test_expecting_message_identifier_enum() {
             Token::Str("Unknown"),
             Token::None,
         ],
-        r#"invalid type: map, expected something strange..."#,
+        "invalid type: map, expected something strange...",
     );
 
     assert_de_tokens_error::<VariantEnum>(
         &[Token::Unit],
-        r#"invalid type: unit value, expected something strange..."#,
+        "invalid type: unit value, expected something strange...",
     );
 
     assert_de_tokens_error::<VariantEnum>(
@@ -2825,7 +2887,7 @@ fn test_expecting_message_identifier_enum() {
             Token::Str("Unknown"),
             Token::None,
         ],
-        r#"invalid type: map, expected something strange..."#,
+        "invalid type: map, expected something strange...",
     );
 }
 

test_suite/tests/test_de.rs

@@ -11,6 +11,7 @@
 #![cfg_attr(feature = "unstable", feature(never_type))]
 
 use fnv::FnvHasher;
+use serde::de::value::{F32Deserializer, F64Deserializer};
 use serde::de::{Deserialize, DeserializeOwned, Deserializer, IntoDeserializer};
 use serde_derive::Deserialize;
 use serde_test::{assert_de_tokens, Configure, Token};
@@ -832,6 +833,26 @@ fn test_f64() {
     test(1.11, &[Token::F64(1.11)]);
 }
 
+#[test]
+fn test_nan() {
+    let f32_deserializer = F32Deserializer::<serde::de::value::Error>::new;
+    let f64_deserializer = F64Deserializer::<serde::de::value::Error>::new;
+
+    let pos_f32_nan = f32_deserializer(f32::NAN.copysign(1.0));
+    let pos_f64_nan = f64_deserializer(f64::NAN.copysign(1.0));
+    assert!(f32::deserialize(pos_f32_nan).unwrap().is_sign_positive());
+    assert!(f32::deserialize(pos_f64_nan).unwrap().is_sign_positive());
+    assert!(f64::deserialize(pos_f32_nan).unwrap().is_sign_positive());
+    assert!(f64::deserialize(pos_f64_nan).unwrap().is_sign_positive());
+
+    let neg_f32_nan = f32_deserializer(f32::NAN.copysign(-1.0));
+    let neg_f64_nan = f64_deserializer(f64::NAN.copysign(-1.0));
+    assert!(f32::deserialize(neg_f32_nan).unwrap().is_sign_negative());
+    assert!(f32::deserialize(neg_f64_nan).unwrap().is_sign_negative());
+    assert!(f64::deserialize(neg_f32_nan).unwrap().is_sign_negative());
+    assert!(f64::deserialize(neg_f64_nan).unwrap().is_sign_negative());
+}
+
 #[test]
 fn test_char() {
     test('a', &[Token::Char('a')]);

test_suite/tests/test_gen.rs

@@ -843,7 +843,7 @@ pub fn is_zero(n: &u8) -> bool {
     *n == 0
 }
 
-fn vec_first_element<T, S>(vec: &Vec<T>, serializer: S) -> StdResult<S::Ok, S::Error>
+fn vec_first_element<T, S>(vec: &[T], serializer: S) -> StdResult<S::Ok, S::Error>
 where
     T: Serialize,
     S: Serializer,

test_suite/tests/ui/remote/unknown_field.stderr

@@ -2,10 +2,12 @@ error[E0609]: no field `b` on type `&remote::S`
   --> tests/ui/remote/unknown_field.rs:12:5
    |
 12 |     b: u8,
-   |     ^ help: a field with a similar name exists: `a`
+   |     ^ unknown field
 
 error[E0560]: struct `remote::S` has no field named `b`
   --> tests/ui/remote/unknown_field.rs:12:5
    |
 12 |     b: u8,
-   |     ^ help: a field with a similar name exists: `a`
+   |     ^ `remote::S` does not have this field
+   |
+   = note: all struct fields are already assigned