From 0726b2c4799fb31705aa8c488209dd865a8fe851 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Mon, 6 Nov 2023 08:06:23 -0800
Subject: [PATCH 1/8] Enable feature(doc_cfg) during docs.rs documentation
 build

---
 serde/Cargo.toml | 2 +-
 serde/src/lib.rs | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index b1a6d3e9b..bb7b60b17 100644
--- a/serde/Cargo.toml
+++ b/serde/Cargo.toml
@@ -29,7 +29,7 @@ features = ["derive", "rc"]
 [package.metadata.docs.rs]
 features = ["derive"]
 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
diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index 8c6a4affc..214fd5bdb 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -98,6 +98,8 @@
 #![doc(html_root_url = "https://docs.rs/serde/1.0.190")]
 // 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:
 //

From ce8fef7e0b917cc5150b3c753fd444c2a5f2acc6 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Mon, 6 Nov 2023 08:06:40 -0800
Subject: [PATCH 2/8] Show that derives are specific to feature="derive" in
 documentation

---
 serde/src/lib.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index 214fd5bdb..8408bbb2e 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -326,6 +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")))]

From 215c2b71ef387e193860b57ee2868f3a2367afaa Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Mon, 6 Nov 2023 08:30:21 -0800
Subject: [PATCH 3/8] Relocate cfg attrs into forwarded_impl macro

This will allow adding #[doc(cfg(feature = "..."))] attributes to the
impl in an upcoming commit.
---
 serde/src/de/impls.rs | 69 +++++++++++++++++++++++++++----------------
 1 file changed, 44 insertions(+), 25 deletions(-)

diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index b7e4c549d..514443260 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -750,10 +750,10 @@ 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
@@ -765,10 +765,14 @@ 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")))]
+    (), Box<CStr>, CString::into_boxed_c_str
+}
 
-forwarded_impl!((T), Reverse<T>, Reverse);
+forwarded_impl! {
+    (T), Reverse<T>, Reverse
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -1728,8 +1732,10 @@ impl<'de> Deserialize<'de> for PathBuf {
     }
 }
 
-#[cfg(feature = "std")]
-forwarded_impl!((), Box<Path>, PathBuf::into_boxed_path);
+forwarded_impl! {
+    #[cfg(feature = "std")]
+    (), Box<Path>, PathBuf::into_boxed_path
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -1800,17 +1806,25 @@ impl<'de> Deserialize<'de> for OsString {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-forwarded_impl!((T), Box<T>, Box::new);
+forwarded_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    (T), Box<T>, Box::new
+}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-forwarded_impl!((T), Box<[T]>, Vec::into_boxed_slice);
+forwarded_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    (T), Box<[T]>, Vec::into_boxed_slice
+}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-forwarded_impl!((), Box<str>, String::into_boxed_str);
+forwarded_impl! {
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    (), 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(all(feature = "std", any(unix, windows)))]
+    (), Box<OsStr>, OsString::into_boxed_os_str
+}
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'de, 'a, T: ?Sized> Deserialize<'de> for Cow<'a, T>
@@ -1867,13 +1881,12 @@ 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>,
@@ -1888,7 +1901,6 @@ 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.
     ///
@@ -1897,10 +1909,10 @@ 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")))]
     Rc
 }
 
-#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1909,6 +1921,7 @@ 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")))]
     Arc
 }
 
@@ -1926,13 +1939,19 @@ 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")]
+    (T), Mutex<T>, Mutex::new
+}
 
-#[cfg(feature = "std")]
-forwarded_impl!((T), RwLock<T>, RwLock::new);
+forwarded_impl! {
+    #[cfg(feature = "std")]
+    (T), RwLock<T>, RwLock::new
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 

From 3f339de36ae3e72fa4b2d683c12d3c37ec19537d Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Mon, 6 Nov 2023 08:39:31 -0800
Subject: [PATCH 4/8] Relocate cfg attrs into seq_impl and map_impl

---
 serde/src/de/impls.rs  | 34 ++++++++++--------
 serde/src/ser/impls.rs | 80 +++++++++++++++++++++++++++++-------------
 2 files changed, 76 insertions(+), 38 deletions(-)

diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 514443260..ebdcfd58d 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -878,9 +878,9 @@ 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,
@@ -888,6 +888,7 @@ 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)*)*,
@@ -975,8 +976,8 @@ 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"))]
     BinaryHeap<T: Ord>,
     seq,
     BinaryHeap::clear,
@@ -985,8 +986,8 @@ seq_impl!(
     BinaryHeap::push
 );
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 seq_impl!(
+    #[cfg(any(feature = "std", feature = "alloc"))]
     BTreeSet<T: Eq + Ord>,
     seq,
     BTreeSet::clear,
@@ -995,8 +996,8 @@ seq_impl!(
     BTreeSet::insert
 );
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 seq_impl!(
+    #[cfg(any(feature = "std", feature = "alloc"))]
     LinkedList<T>,
     seq,
     LinkedList::clear,
@@ -1005,8 +1006,8 @@ seq_impl!(
     LinkedList::push_back
 );
 
-#[cfg(feature = "std")]
 seq_impl!(
+    #[cfg(feature = "std")]
     HashSet<T: Eq + Hash, S: BuildHasher + Default>,
     seq,
     HashSet::clear,
@@ -1015,8 +1016,8 @@ seq_impl!(
     HashSet::insert
 );
 
-#[cfg(any(feature = "std", feature = "alloc"))]
 seq_impl!(
+    #[cfg(any(feature = "std", feature = "alloc"))]
     VecDeque<T>,
     seq,
     VecDeque::clear,
@@ -1373,13 +1374,14 @@ 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)*)*,
@@ -1428,15 +1430,19 @@ 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"))]
+    BTreeMap<K: Ord, V>,
+    map,
+    BTreeMap::new(),
+}
 
-#[cfg(feature = "std")]
-map_impl!(
+map_impl! {
+    #[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()),
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 39acba315..75f84b248 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -179,9 +179,13 @@ 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,
@@ -197,9 +201,13 @@ 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)*)*,
@@ -216,23 +224,35 @@ macro_rules! seq_impl {
     }
 }
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-seq_impl!(BinaryHeap<T: Ord>);
+seq_impl! {
+    #[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"))]
+    BTreeSet<T: Ord>
+}
 
-#[cfg(feature = "std")]
-seq_impl!(HashSet<T: Eq + Hash, H: BuildHasher>);
+seq_impl! {
+    #[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"))]
+    LinkedList<T>
+}
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-seq_impl!(Vec<T>);
+seq_impl! {
+    #[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"))]
+    VecDeque<T>
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -394,9 +414,13 @@ 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,
@@ -413,9 +437,13 @@ 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)*)*,
@@ -433,11 +461,15 @@ macro_rules! map_impl {
     }
 }
 
-#[cfg(any(feature = "std", feature = "alloc"))]
-map_impl!(BTreeMap<K: Ord, V>);
+map_impl! {
+    #[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")]
+    HashMap<K: Eq + Hash, V, H: BuildHasher>
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 

From 64f949b37b5b6cd1c02f71ab13d8beae53150b5d Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Mon, 6 Nov 2023 08:41:40 -0800
Subject: [PATCH 5/8] Relocate cfg attrs into parse_ip_impl and
 parse_socket_impl

---
 serde/src/de/impls.rs | 41 +++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index ebdcfd58d..f4c313ef2 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -1446,9 +1446,12 @@ map_impl! {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[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
@@ -1595,15 +1598,23 @@ impl<'de> Deserialize<'de> for net::IpAddr {
     }
 }
 
-#[cfg(feature = "std")]
-parse_ip_impl!("IPv4 address" net::Ipv4Addr; 4);
+parse_ip_impl! {
+    #[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")]
+    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
@@ -1638,11 +1649,17 @@ 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")]
+    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")]
+    net::SocketAddrV6, "IPv6 socket address",
+    |(ip, port)| net::SocketAddrV6::new(ip, port, 0, 0),
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 

From 05c2509d07ae52a15db3675aa6e942620d988c3a Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Mon, 6 Nov 2023 11:13:28 -0800
Subject: [PATCH 6/8] Relocate cfg attrs into deref_impl

---
 serde/src/ser/impls.rs | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 75f84b248..fdf3994d7 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -475,10 +475,10 @@ map_impl! {
 
 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>
@@ -491,13 +491,19 @@ 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"))]
+    <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.
     ///
@@ -507,10 +513,10 @@ deref_impl! {
     /// repeated data.
     ///
     /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
+    #[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.
     ///
@@ -520,11 +526,14 @@ deref_impl! {
     /// repeated data.
     ///
     /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
+    #[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"))]
+    <'a, T: ?Sized> Serialize for Cow<'a, T> where T: Serialize + ToOwned
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 

From 9dacfbbd69d7911910eb641ed3deb6ce723059f0 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Mon, 6 Nov 2023 08:29:16 -0800
Subject: [PATCH 7/8] Fill in more doc(cfg) attributes

---
 serde/src/de/impls.rs  | 41 +++++++++++++++++++++++++++++++++++++++++
 serde/src/de/mod.rs    |  2 ++
 serde/src/de/value.rs  | 12 ++++++++++++
 serde/src/ser/impls.rs | 38 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 93 insertions(+)

diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index f4c313ef2..1f05c5333 100644
--- a/serde/src/de/impls.rs
+++ b/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
@@ -596,6 +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
@@ -739,6 +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
@@ -767,6 +770,7 @@ 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"))))]
     (), Box<CStr>, CString::into_boxed_c_str
 }
 
@@ -978,6 +982,7 @@ 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"))))]
     BinaryHeap<T: Ord>,
     seq,
     BinaryHeap::clear,
@@ -988,6 +993,7 @@ seq_impl!(
 
 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,
@@ -998,6 +1004,7 @@ seq_impl!(
 
 seq_impl!(
     #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
     LinkedList<T>,
     seq,
     LinkedList::clear,
@@ -1008,6 +1015,7 @@ seq_impl!(
 
 seq_impl!(
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     HashSet<T: Eq + Hash, S: BuildHasher + Default>,
     seq,
     HashSet::clear,
@@ -1018,6 +1026,7 @@ seq_impl!(
 
 seq_impl!(
     #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
     VecDeque<T>,
     seq,
     VecDeque::clear,
@@ -1029,6 +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>,
@@ -1432,6 +1442,7 @@ macro_rules! map_impl {
 
 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(),
@@ -1439,6 +1450,7 @@ 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()),
@@ -1580,6 +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
@@ -1600,11 +1613,13 @@ impl<'de> Deserialize<'de> for net::IpAddr {
 
 parse_ip_impl! {
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     net::Ipv4Addr, "IPv4 address", 4
 }
 
 parse_ip_impl! {
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     net::Ipv6Addr, "IPv6 address", 16
 }
 
@@ -1631,6 +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
@@ -1651,12 +1667,14 @@ impl<'de> Deserialize<'de> for net::SocketAddr {
 
 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),
 }
 
 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),
 }
@@ -1692,6 +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
@@ -1746,6 +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
@@ -1757,6 +1777,7 @@ impl<'de> Deserialize<'de> for PathBuf {
 
 forwarded_impl! {
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     (), Box<Path>, PathBuf::into_boxed_path
 }
 
@@ -1818,6 +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
@@ -1831,25 +1853,30 @@ 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"))))]
     (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,
@@ -1871,6 +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>,
@@ -1889,6 +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>,
@@ -1933,6 +1968,7 @@ 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")))))]
     Rc
 }
 
@@ -1945,6 +1981,7 @@ 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")))))]
     Arc
 }
 
@@ -1968,11 +2005,13 @@ forwarded_impl! {
 
 forwarded_impl! {
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     (T), Mutex<T>, Mutex::new
 }
 
 forwarded_impl! {
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     (T), RwLock<T>, RwLock::new
 }
 
@@ -2127,6 +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
@@ -2962,6 +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
diff --git a/serde/src/de/mod.rs b/serde/src/de/mod.rs
index afbc23af6..c22ed070b 100644
--- a/serde/src/de/mod.rs
+++ b/serde/src/de/mod.rs
@@ -1525,6 +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,
@@ -1583,6 +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,
diff --git a/serde/src/de/value.rs b/serde/src/de/value.rs
index 1234b8103..b229ebab7 100644
--- a/serde/src/de/value.rs
+++ b/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,
@@ -562,6 +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>,
@@ -578,6 +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,
@@ -665,6 +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>,
@@ -681,6 +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,
@@ -999,6 +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>,
@@ -1012,6 +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,
@@ -1025,6 +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,
@@ -1411,6 +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,
@@ -1425,6 +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,
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index fdf3994d7..8c70634af 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -48,6 +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>
@@ -70,6 +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>
@@ -81,6 +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>
@@ -226,31 +229,37 @@ macro_rules! seq_impl {
 
 seq_impl! {
     #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, 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"))))]
     BTreeSet<T: Ord>
 }
 
 seq_impl! {
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, 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"))))]
     LinkedList<T>
 }
 
 seq_impl! {
     #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, 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"))))]
     VecDeque<T>
 }
 
@@ -359,6 +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
@@ -463,11 +473,13 @@ macro_rules! map_impl {
 
 map_impl! {
     #[cfg(any(feature = "std", feature = "alloc"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "std", feature = "alloc"))))]
     BTreeMap<K: Ord, V>
 }
 
 map_impl! {
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     HashMap<K: Eq + Hash, V, H: BuildHasher>
 }
 
@@ -501,6 +513,7 @@ deref_impl! {
 
 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
 }
 
@@ -514,6 +527,7 @@ 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")))))]
     <T: ?Sized> Serialize for Rc<T> where T: Serialize
 }
 
@@ -527,11 +541,13 @@ 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")))))]
     <T: ?Sized> Serialize for Arc<T> where T: Serialize
 }
 
 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
 }
 
@@ -541,6 +557,10 @@ 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"))))
+)]
 impl<T: ?Sized> Serialize for RcWeak<T>
 where
     T: Serialize,
@@ -557,6 +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,
@@ -633,6 +657,7 @@ where
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<T: ?Sized> Serialize for Mutex<T>
 where
     T: Serialize,
@@ -649,6 +674,7 @@ where
 }
 
 #[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 impl<T: ?Sized> Serialize for RwLock<T>
 where
     T: Serialize,
@@ -702,6 +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
@@ -746,6 +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
@@ -816,6 +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
@@ -840,6 +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
@@ -856,6 +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
@@ -880,6 +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
@@ -896,6 +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
@@ -917,6 +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
@@ -930,6 +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
@@ -940,6 +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>
@@ -962,6 +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
@@ -1006,6 +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

From c8bc97c81be0251670e3f3f279dc45820ad87784 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Mon, 6 Nov 2023 11:22:25 -0800
Subject: [PATCH 8/8] Document "rc" and "unstable" features on docs.rs

---
 serde/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index bb7b60b17..14603e70d 100644
--- a/serde/Cargo.toml
+++ b/serde/Cargo.toml
@@ -27,7 +27,7 @@ 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 = ["--cfg", "doc_cfg", "--generate-link-to-definition"]