New feature rustdoc_use_unstable to use unstable rustdoc features

Generate documentation about supported platforms automatically if the
feature is enabled.

Don't pass `--cfg docsrs` to rustdoc for docs.rs builds, it's already
passed.

Author: proski

Cargo.toml

@@ -29,7 +29,6 @@ include       = [
 
 [package.metadata.docs.rs]
 all-features = true
-rustdoc-args = ["--cfg", "docsrs"]
 targets = ["aarch64-apple-ios", "aarch64-linux-android", "x86_64-apple-darwin", "x86_64-unknown-fuchsia", "x86_64-pc-windows-msvc", "x86_64-pc-solaris", "x86_64-unknown-freebsd", "x86_64-unknown-illumos", "x86_64-unknown-linux-gnu", "x86_64-unknown-linux-musl", "x86_64-unknown-netbsd", "x86_64-unknown-redox", "armv7-linux-androideabi", "i686-linux-android"]
 
 [package.metadata.playground]
@@ -51,3 +50,5 @@ features = [
 [features]
 # Enable all API, even ones not available on all OSs.
 all = []
+# Use unstable Rust features for better documentation.
+rustdoc_use_unstable = []

src/lib.rs

@@ -51,8 +51,8 @@
 //! that are not available on all OSs.
 
 #![deny(missing_docs, missing_debug_implementations, rust_2018_idioms)]
-// Show required OS/features on docs.rs.
-#![cfg_attr(docsrs, feature(doc_cfg))]
+// Automatically generate required OS/features in documentation
+#![cfg_attr(feature = "rustdoc_use_unstable", feature(doc_auto_cfg))]
 // Disallow warnings when running tests.
 #![cfg_attr(test, deny(warnings))]
 // Disallow warnings in examples.
@@ -266,20 +266,14 @@ impl Type {
     ///
     /// Used for the DCCP protocol.
     #[cfg(all(feature = "all", target_os = "linux"))]
-    #[cfg_attr(docsrs, doc(cfg(all(feature = "all", target_os = "linux"))))]
     pub const DCCP: Type = Type(sys::SOCK_DCCP);
 
     /// Type corresponding to `SOCK_SEQPACKET`.
     #[cfg(all(feature = "all", not(target_os = "espidf")))]
-    #[cfg_attr(docsrs, doc(cfg(all(feature = "all", not(target_os = "espidf")))))]
     pub const SEQPACKET: Type = Type(sys::SOCK_SEQPACKET);
 
     /// Type corresponding to `SOCK_RAW`.
     #[cfg(all(feature = "all", not(any(target_os = "redox", target_os = "espidf"))))]
-    #[cfg_attr(
-        docsrs,
-        doc(cfg(all(feature = "all", not(any(target_os = "redox", target_os = "espidf")))))
-    )]
     pub const RAW: Type = Type(sys::SOCK_RAW);
 }
 
@@ -324,7 +318,6 @@ impl Protocol {
 
     /// Protocol corresponding to `DCCP`.
     #[cfg(all(feature = "all", target_os = "linux"))]
-    #[cfg_attr(docsrs, doc(cfg(all(feature = "all", target_os = "linux"))))]
     pub const DCCP: Protocol = Protocol(sys::IPPROTO_DCCP);
 
     /// Protocol corresponding to `SCTP`.
@@ -364,7 +357,6 @@ impl From<Protocol> for c_int {
 ///
 /// Flags provide additional information about incoming messages.
 #[cfg(not(target_os = "redox"))]
-#[cfg_attr(docsrs, doc(cfg(not(target_os = "redox"))))]
 #[derive(Copy, Clone, Eq, PartialEq)]
 pub struct RecvFlags(c_int);
 
@@ -523,24 +515,6 @@ impl TcpKeepalive {
         target_os = "watchos",
         target_os = "windows",
     ))]
-    #[cfg_attr(
-        docsrs,
-        doc(cfg(any(
-            target_os = "android",
-            target_os = "dragonfly",
-            target_os = "freebsd",
-            target_os = "fuchsia",
-            target_os = "illumos",
-            target_os = "ios",
-            target_os = "visionos",
-            target_os = "linux",
-            target_os = "macos",
-            target_os = "netbsd",
-            target_os = "tvos",
-            target_os = "watchos",
-            target_os = "windows",
-        )))
-    )]
     pub const fn with_interval(self, interval: Duration) -> Self {
         Self {
             interval: Some(interval),
@@ -569,26 +543,6 @@ impl TcpKeepalive {
             target_os = "watchos",
         )
     ))]
-    #[cfg_attr(
-        docsrs,
-        doc(cfg(all(
-            feature = "all",
-            any(
-                target_os = "android",
-                target_os = "dragonfly",
-                target_os = "freebsd",
-                target_os = "fuchsia",
-                target_os = "illumos",
-                target_os = "ios",
-                target_os = "visionos",
-                target_os = "linux",
-                target_os = "macos",
-                target_os = "netbsd",
-                target_os = "tvos",
-                target_os = "watchos",
-            )
-        )))
-    )]
     pub const fn with_retries(self, retries: u32) -> Self {
         Self {
             retries: Some(retries),