Add doc(cfg(feature = "std")) attribute where appropriate

src/de.rs

@@ -2492,6 +2492,7 @@ where
 /// the JSON map or some number is too big to fit in the expected primitive
 /// type.
 #[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 pub fn from_reader<R, T>(rdr: R) -> Result<T>
 where
     R: crate::io::Read,

src/lib.rs

@@ -454,6 +454,7 @@ pub mod de;
 pub mod error;
 pub mod map;
 #[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 pub mod ser;
 #[cfg(not(feature = "std"))]
 mod ser;

src/read.rs

@@ -140,6 +140,7 @@ where
 
 /// JSON input source that reads from a std::io input stream.
 #[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 pub struct IoRead<R>
 where
     R: io::Read,

src/ser.rs

@@ -8,6 +8,7 @@ use serde::ser::{self, Impossible, Serialize};
 use serde::serde_if_integer128;
 
 /// A structure for serializing Rust values into JSON.
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 pub struct Serializer<W, F = CompactFormatter> {
     writer: W,
     formatter: F,
@@ -2141,6 +2142,7 @@ static ESCAPE: [u8; 256] = [
 /// Serialization can fail if `T`'s implementation of `Serialize` decides to
 /// fail, or if `T` contains a map with non-string keys.
 #[inline]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 pub fn to_writer<W, T>(writer: W, value: &T) -> Result<()>
 where
     W: io::Write,
@@ -2159,6 +2161,7 @@ where
 /// Serialization can fail if `T`'s implementation of `Serialize` decides to
 /// fail, or if `T` contains a map with non-string keys.
 #[inline]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 pub fn to_writer_pretty<W, T>(writer: W, value: &T) -> Result<()>
 where
     W: io::Write,