Cleanup: replace cfg-if with our macros (#361)

* Cleanup: replace cfg-if with our macros

* Prefix macros with cfg_

* Remove #[macro_export] from internal macros

Cargo.toml

@@ -21,13 +21,12 @@ features = ["docs"]
 rustdoc-args = ["--cfg", "feature=\"docs\""]
 
 [features]
-docs = ["broadcaster"]
+docs = ["unstable"]
 unstable = ["broadcaster"]
 
 [dependencies]
 async-macros = "1.0.0"
 async-task = "1.0.0"
-cfg-if = "0.1.9"
 crossbeam-channel = "0.3.9"
 crossbeam-deque = "0.7.1"
 crossbeam-utils = "0.6.6"

src/fs/dir_builder.rs

@@ -1,7 +1,5 @@
 use std::future::Future;
 
-use cfg_if::cfg_if;
-
 use crate::io;
 use crate::path::Path;
 use crate::task::blocking;
@@ -113,22 +111,13 @@ impl DirBuilder {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::fs::DirBuilderExt;
-    } else if #[cfg(unix)] {
-        use std::os::unix::fs::DirBuilderExt;
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl DirBuilderExt for DirBuilder {
         fn mode(&mut self, mode: u32) -> &mut Self {
             self.mode = Some(mode);
             self
         }
     }
-    }
 }

src/fs/dir_entry.rs

@@ -2,8 +2,6 @@ use std::ffi::OsString;
 use std::fmt;
 use std::sync::Arc;
 
-use cfg_if::cfg_if;
-
 use crate::fs::{FileType, Metadata};
 use crate::io;
 use crate::path::PathBuf;
@@ -160,21 +158,12 @@ impl fmt::Debug for DirEntry {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::fs::DirEntryExt;
-    } else if #[cfg(unix)] {
-        use std::os::unix::fs::DirEntryExt;
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl DirEntryExt for DirEntry {
         fn ino(&self) -> u64 {
             self.0.ino()
         }
     }
-    }
 }

src/fs/file.rs

@@ -7,8 +7,6 @@ use std::pin::Pin;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
 
-use cfg_if::cfg_if;
-
 use crate::fs::{Metadata, Permissions};
 use crate::future;
 use crate::io::{self, Read, Seek, SeekFrom, Write};
@@ -401,20 +399,9 @@ impl From<std::fs::File> for File {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-        use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
-    } else if #[cfg(unix)] {
-        use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-    } else if #[cfg(windows)] {
-        use std::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl AsRawFd for File {
         fn as_raw_fd(&self) -> RawFd {
             self.file.as_raw_fd()
@@ -436,12 +423,11 @@ cfg_if! {
                 .into_raw_fd()
         }
     }
-    }
 }
 
-#[cfg_attr(feature = "docs", doc(cfg(windows)))]
-cfg_if! {
-    if #[cfg(any(windows, feature = "docs"))] {
+cfg_windows! {
+    use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
+
     impl AsRawHandle for File {
         fn as_raw_handle(&self) -> RawHandle {
             self.file.as_raw_handle()
@@ -463,7 +449,6 @@ cfg_if! {
                 .into_raw_handle()
         }
     }
-    }
 }
 
 /// An async mutex with non-borrowing lock guards.

src/fs/file_type.rs

@@ -1,7 +1,8 @@
-use cfg_if::cfg_if;
+cfg_not_docs! {
+    pub use std::fs::FileType;
+}
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_docs! {
     /// The type of a file or directory.
     ///
     /// A file type is returned by [`Metadata::file_type`].
@@ -80,7 +81,4 @@ cfg_if! {
             unimplemented!()
         }
     }
-    } else {
-        pub use std::fs::FileType;
-    }
 }

src/fs/metadata.rs

@@ -1,5 +1,3 @@
-use cfg_if::cfg_if;
-
 use crate::io;
 use crate::path::Path;
 use crate::task::blocking;
@@ -39,8 +37,11 @@ pub async fn metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
     blocking::spawn(move || std::fs::metadata(path)).await
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_not_docs! {
+    pub use std::fs::Metadata;
+}
+
+cfg_docs! {
     use std::time::SystemTime;
 
     use crate::fs::{FileType, Permissions};
@@ -225,7 +226,4 @@ cfg_if! {
             unimplemented!()
         }
     }
-    } else {
-        pub use std::fs::Metadata;
-    }
 }

src/fs/open_options.rs

@@ -1,7 +1,5 @@
 use std::future::Future;
 
-use cfg_if::cfg_if;
-
 use crate::fs::File;
 use crate::io;
 use crate::path::Path;
@@ -296,17 +294,9 @@ impl Default for OpenOptions {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::fs::OpenOptionsExt;
-    } else if #[cfg(unix)] {
-        use std::os::unix::fs::OpenOptionsExt;
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl OpenOptionsExt for OpenOptions {
         fn mode(&mut self, mode: u32) -> &mut Self {
             self.0.mode(mode);
@@ -318,5 +308,4 @@ cfg_if! {
             self
         }
     }
-    }
 }

src/fs/permissions.rs

@@ -1,7 +1,8 @@
-use cfg_if::cfg_if;
+cfg_not_docs! {
+    pub use std::fs::Permissions;
+}
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_docs! {
     /// A set of permissions on a file or directory.
     ///
     /// This type is a re-export of [`std::fs::Permissions`].
@@ -52,7 +53,4 @@ cfg_if! {
             unimplemented!()
         }
     }
-    } else {
-        pub use std::fs::Permissions;
-    }
 }

src/future/future.rs

@@ -1,15 +1,9 @@
-use crate::utils::extension_trait;
-
-cfg_if::cfg_if! {
-    if #[cfg(feature = "docs")] {
+extension_trait! {
     use std::pin::Pin;
     use std::ops::{Deref, DerefMut};
 
     use crate::task::{Context, Poll};
-    }
-}
 
-extension_trait! {
     #[doc = r#"
         A future represents an asynchronous computation.
 

src/future/into_future.rs

@@ -30,7 +30,7 @@ use crate::future::Future;
 ///     }
 /// }
 /// ```
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 pub trait IntoFuture {
     /// The type of value produced on completion.

src/future/mod.rs

@@ -44,12 +44,6 @@
 #[doc(inline)]
 pub use async_macros::{join, try_join};
 
-#[doc(inline)]
-#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-pub use async_macros::{select, try_select};
-
-use cfg_if::cfg_if;
-
 pub use future::Future;
 pub use pending::pending;
 pub use poll_fn::poll_fn;
@@ -62,10 +56,10 @@ mod poll_fn;
 mod ready;
 mod timeout;
 
-cfg_if! {
-    if #[cfg(any(feature = "unstable", feature = "docs"))] {
-        mod into_future;
+cfg_unstable! {
+    #[doc(inline)]
+    pub use async_macros::{select, try_select};
 
     pub use into_future::IntoFuture;
-    }
+    mod into_future;
 }

src/io/buf_read/mod.rs

@@ -12,19 +12,12 @@ use read_until::ReadUntilFuture;
 use std::mem;
 use std::pin::Pin;
 
-use cfg_if::cfg_if;
-
 use crate::io;
 use crate::task::{Context, Poll};
-use crate::utils::extension_trait;
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+extension_trait! {
     use std::ops::{Deref, DerefMut};
-    }
-}
 
-extension_trait! {
     #[doc = r#"
         Allows reading from a buffered byte stream.
 

src/io/read/mod.rs

@@ -13,23 +13,17 @@ use read_to_end::{read_to_end_internal, ReadToEndFuture};
 use read_to_string::ReadToStringFuture;
 use read_vectored::ReadVectoredFuture;
 
-use cfg_if::cfg_if;
 use std::mem;
 
 use crate::io::IoSliceMut;
-use crate::utils::extension_trait;
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+extension_trait! {
     use std::pin::Pin;
     use std::ops::{Deref, DerefMut};
 
     use crate::io;
     use crate::task::{Context, Poll};
-    }
-}
 
-extension_trait! {
     #[doc = r#"
         Allows reading from a byte stream.
 

src/io/seek/mod.rs

@@ -1,19 +1,16 @@
-use std::pin::Pin;
+mod seek;
 
-use cfg_if::cfg_if;
+use seek::SeekFuture;
 
-use crate::future::Future;
-use crate::io::{self, SeekFrom};
-use crate::task::{Context, Poll};
-use crate::utils::extension_trait;
+use crate::io::SeekFrom;
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+extension_trait! {
     use std::ops::{Deref, DerefMut};
-    }
-}
+    use std::pin::Pin;
+
+    use crate::io;
+    use crate::task::{Context, Poll};
 
-extension_trait! {
     #[doc = r#"
         Allows seeking through a byte stream.
 
@@ -114,19 +111,3 @@ extension_trait! {
         }
     }
 }
-
-#[doc(hidden)]
-#[allow(missing_debug_implementations)]
-pub struct SeekFuture<'a, T: Unpin + ?Sized> {
-    seeker: &'a mut T,
-    pos: SeekFrom,
-}
-
-impl<T: SeekExt + Unpin + ?Sized> Future for SeekFuture<'_, T> {
-    type Output = io::Result<u64>;
-
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        let pos = self.pos;
-        Pin::new(&mut *self.seeker).poll_seek(cx, pos)
-    }
-}

src/io/seek/seek.rs

@@ -0,0 +1,21 @@
+use std::pin::Pin;
+
+use crate::future::Future;
+use crate::io::{self, Seek, SeekFrom};
+use crate::task::{Context, Poll};
+
+#[doc(hidden)]
+#[allow(missing_debug_implementations)]
+pub struct SeekFuture<'a, T: Unpin + ?Sized> {
+    pub(crate) seeker: &'a mut T,
+    pub(crate) pos: SeekFrom,
+}
+
+impl<T: Seek + Unpin + ?Sized> Future for SeekFuture<'_, T> {
+    type Output = io::Result<u64>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let pos = self.pos;
+        Pin::new(&mut *self.seeker).poll_seek(cx, pos)
+    }
+}

src/io/stderr.rs

@@ -1,8 +1,6 @@
 use std::pin::Pin;
 use std::sync::Mutex;
 
-use cfg_if::cfg_if;
-
 use crate::future::Future;
 use crate::io::{self, Write};
 use crate::task::{blocking, Context, JoinHandle, Poll};
@@ -162,35 +160,22 @@ impl Write for Stderr {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::io::{AsRawFd, RawFd};
-        use crate::os::windows::io::{AsRawHandle, RawHandle};
-    } else if #[cfg(unix)] {
-        use std::os::unix::io::{AsRawFd, RawFd};
-    } else if #[cfg(windows)] {
-        use std::os::windows::io::{AsRawHandle, RawHandle};
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl AsRawFd for Stderr {
         fn as_raw_fd(&self) -> RawFd {
             std::io::stderr().as_raw_fd()
         }
     }
-    }
 }
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(windows, feature = "docs"))] {
+cfg_windows! {
+    use crate::os::windows::io::{AsRawHandle, RawHandle};
+
     impl AsRawHandle for Stderr {
         fn as_raw_handle(&self) -> RawHandle {
             std::io::stderr().as_raw_handle()
         }
     }
-    }
 }

src/io/stdin.rs

@@ -1,8 +1,6 @@
 use std::pin::Pin;
 use std::sync::Mutex;
 
-use cfg_if::cfg_if;
-
 use crate::future::{self, Future};
 use crate::io::{self, Read};
 use crate::task::{blocking, Context, JoinHandle, Poll};
@@ -186,35 +184,22 @@ impl Read for Stdin {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::io::{AsRawFd, RawFd};
-        use crate::os::windows::io::{AsRawHandle, RawHandle};
-    } else if #[cfg(unix)] {
-        use std::os::unix::io::{AsRawFd, RawFd};
-    } else if #[cfg(windows)] {
-        use std::os::windows::io::{AsRawHandle, RawHandle};
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl AsRawFd for Stdin {
         fn as_raw_fd(&self) -> RawFd {
             std::io::stdin().as_raw_fd()
         }
     }
-    }
 }
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(windows, feature = "docs"))] {
+cfg_windows! {
+    use crate::os::windows::io::{AsRawHandle, RawHandle};
+
     impl AsRawHandle for Stdin {
         fn as_raw_handle(&self) -> RawHandle {
             std::io::stdin().as_raw_handle()
         }
     }
-    }
 }

src/io/stdout.rs

@@ -1,8 +1,6 @@
 use std::pin::Pin;
 use std::sync::Mutex;
 
-use cfg_if::cfg_if;
-
 use crate::future::Future;
 use crate::io::{self, Write};
 use crate::task::{blocking, Context, JoinHandle, Poll};
@@ -162,35 +160,22 @@ impl Write for Stdout {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::io::{AsRawFd, RawFd};
-        use crate::os::windows::io::{AsRawHandle, RawHandle};
-    } else if #[cfg(unix)] {
-        use std::os::unix::io::{AsRawFd, RawFd};
-    } else if #[cfg(windows)] {
-        use std::os::windows::io::{AsRawHandle, RawHandle};
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl AsRawFd for Stdout {
         fn as_raw_fd(&self) -> RawFd {
             std::io::stdout().as_raw_fd()
         }
     }
-    }
 }
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(windows, feature = "docs"))] {
+cfg_windows! {
+    use crate::os::windows::io::{AsRawHandle, RawHandle};
+
     impl AsRawHandle for Stdout {
         fn as_raw_handle(&self) -> RawHandle {
             std::io::stdout().as_raw_handle()
         }
     }
-    }
 }

src/io/write/mod.rs

@@ -10,22 +10,14 @@ use write_all::WriteAllFuture;
 use write_fmt::WriteFmtFuture;
 use write_vectored::WriteVectoredFuture;
 
-use cfg_if::cfg_if;
+use crate::io::{self, IoSlice};
 
-use crate::io::IoSlice;
-use crate::utils::extension_trait;
-
-use crate::io;
-
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+extension_trait! {
     use std::pin::Pin;
     use std::ops::{Deref, DerefMut};
+
     use crate::task::{Context, Poll};
-    }
-}
 
-extension_trait! {
     #[doc = r#"
         Allows writing to a byte stream.
 

src/lib.rs

@@ -48,7 +48,8 @@
 #![doc(html_logo_url = "https://async.rs/images/logo--hero.svg")]
 #![recursion_limit = "1024"]
 
-use cfg_if::cfg_if;
+#[macro_use]
+mod utils;
 
 pub mod fs;
 pub mod future;
@@ -61,11 +62,8 @@ pub mod stream;
 pub mod sync;
 pub mod task;
 
-cfg_if! {
-    if #[cfg(any(feature = "unstable", feature = "docs"))] {
-        #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
+cfg_unstable! {
     pub mod pin;
-        #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
     pub mod process;
 
     mod unit;
@@ -74,13 +72,9 @@ cfg_if! {
     mod option;
     mod string;
     mod collections;
-    }
+
+    #[doc(inline)]
+    pub use std::{write, writeln};
 }
 
 mod macros;
-pub(crate) mod utils;
-
-#[cfg(any(feature = "unstable", feature = "docs"))]
-#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[doc(inline)]
-pub use std::{write, writeln};

src/macros.rs

@@ -43,7 +43,7 @@
 /// #
 /// # })
 /// ```
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[macro_export]
 macro_rules! print {
@@ -81,7 +81,7 @@ macro_rules! print {
 /// #
 /// # })
 /// ```
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[macro_export]
 macro_rules! println {
@@ -119,7 +119,7 @@ macro_rules! println {
 /// #
 /// # })
 /// ```
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[macro_export]
 macro_rules! eprint {
@@ -153,7 +153,7 @@ macro_rules! eprint {
 /// #
 /// # })
 /// ```
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[macro_export]
 macro_rules! eprintln {

src/net/addr.rs

@@ -3,25 +3,23 @@ use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 use std::net::{SocketAddr, SocketAddrV4, SocketAddrV6};
 use std::pin::Pin;
 
-use cfg_if::cfg_if;
-
 use crate::future::Future;
 use crate::io;
 use crate::task::{blocking, Context, JoinHandle, Poll};
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_not_docs! {
+    macro_rules! ret {
+        (impl Future<Output = $out:ty>, $fut:ty) => ($fut);
+    }
+}
+
+cfg_docs! {
     #[doc(hidden)]
     pub struct ImplFuture<T>(std::marker::PhantomData<T>);
 
     macro_rules! ret {
         (impl Future<Output = $out:ty>, $fut:ty) => (ImplFuture<$out>);
     }
-    } else {
-        macro_rules! ret {
-            (impl Future<Output = $out:ty>, $fut:ty) => ($fut);
-        }
-    }
 }
 
 /// Converts or resolves addresses to [`SocketAddr`] values.

src/net/tcp/listener.rs

@@ -1,13 +1,10 @@
 use std::net::SocketAddr;
 use std::pin::Pin;
 
-use cfg_if::cfg_if;
-
-use super::TcpStream;
 use crate::future::{self, Future};
 use crate::io;
 use crate::net::driver::Watcher;
-use crate::net::ToSocketAddrs;
+use crate::net::{TcpStream, ToSocketAddrs};
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
@@ -213,20 +210,9 @@ impl From<std::net::TcpListener> for TcpListener {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-        // use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
-    } else if #[cfg(unix)] {
-        use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-    } else if #[cfg(windows)] {
-        // use std::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl AsRawFd for TcpListener {
         fn as_raw_fd(&self) -> RawFd {
             self.watcher.get_ref().as_raw_fd()
@@ -244,12 +230,11 @@ cfg_if! {
             self.watcher.into_inner().into_raw_fd()
         }
     }
-    }
 }
 
-#[cfg_attr(feature = "docs", doc(cfg(windows)))]
-cfg_if! {
-    if #[cfg(any(windows, feature = "docs"))] {
+cfg_windows! {
+    // use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
+    //
     // impl AsRawSocket for TcpListener {
     //     fn as_raw_socket(&self) -> RawSocket {
     //         self.raw_socket
@@ -267,5 +252,4 @@ cfg_if! {
     //         self.raw_socket
     //     }
     // }
-    }
 }

src/net/tcp/stream.rs

@@ -2,8 +2,6 @@ use std::io::{IoSlice, IoSliceMut, Read as _, Write as _};
 use std::net::SocketAddr;
 use std::pin::Pin;
 
-use cfg_if::cfg_if;
-
 use crate::future;
 use crate::io::{self, Read, Write};
 use crate::net::driver::Watcher;
@@ -367,20 +365,9 @@ impl From<std::net::TcpStream> for TcpStream {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-        // use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
-    } else if #[cfg(unix)] {
-        use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-    } else if #[cfg(windows)] {
-        // use std::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl AsRawFd for TcpStream {
         fn as_raw_fd(&self) -> RawFd {
             self.watcher.get_ref().as_raw_fd()
@@ -398,12 +385,11 @@ cfg_if! {
             self.watcher.into_inner().into_raw_fd()
         }
     }
-    }
 }
 
-#[cfg_attr(feature = "docs", doc(cfg(windows)))]
-cfg_if! {
-    if #[cfg(any(windows, feature = "docs"))] {
+cfg_windows! {
+    // use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
+    //
     // impl AsRawSocket for TcpStream {
     //     fn as_raw_socket(&self) -> RawSocket {
     //         self.raw_socket
@@ -421,5 +407,4 @@ cfg_if! {
     //         self.raw_socket
     //     }
     // }
-    }
 }

src/net/udp/mod.rs

@@ -1,7 +1,5 @@
 use std::io;
 use std::net::SocketAddr;
-
-use cfg_if::cfg_if;
 use std::net::{Ipv4Addr, Ipv6Addr};
 
 use crate::future;
@@ -463,20 +461,9 @@ impl From<std::net::UdpSocket> for UdpSocket {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_unix! {
     use crate::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-        // use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
-    } else if #[cfg(unix)] {
-        use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-    } else if #[cfg(windows)] {
-        // use std::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
-    }
-}
 
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-cfg_if! {
-    if #[cfg(any(unix, feature = "docs"))] {
     impl AsRawFd for UdpSocket {
         fn as_raw_fd(&self) -> RawFd {
             self.watcher.get_ref().as_raw_fd()
@@ -494,13 +481,10 @@ cfg_if! {
             self.watcher.into_inner().into_raw_fd()
         }
     }
-    }
 }
 
-#[cfg_attr(feature = "docs", doc(cfg(windows)))]
-cfg_if! {
-    if #[cfg(any(windows, feature = "docs"))] {
-        // use std::os::windows::io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket};
+cfg_windows! {
+    // use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
     //
     // impl AsRawSocket for UdpSocket {
     //     fn as_raw_socket(&self) -> RawSocket {
@@ -519,5 +503,4 @@ cfg_if! {
     //         self.raw_socket
     //     }
     // }
-    }
 }

src/os/mod.rs

@@ -1,9 +1,9 @@
 //! OS-specific extensions.
 
-#[cfg(any(unix, feature = "docs"))]
-#[cfg_attr(feature = "docs", doc(cfg(unix)))]
-pub mod unix;
+cfg_unix! {
+    pub mod unix;
+}
 
-#[cfg(any(windows, feature = "docs"))]
-#[cfg_attr(feature = "docs", doc(cfg(windows)))]
-pub mod windows;
+cfg_windows! {
+    pub mod windows;
+}

src/os/unix/fs.rs

@@ -1,7 +1,5 @@
 //! Unix-specific filesystem extensions.
 
-use cfg_if::cfg_if;
-
 use crate::io;
 use crate::path::Path;
 use crate::task::blocking;
@@ -31,8 +29,11 @@ pub async fn symlink<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Resu
     blocking::spawn(move || std::os::unix::fs::symlink(&src, &dst)).await
 }
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_not_docs! {
+    pub use std::os::unix::fs::{DirBuilderExt, DirEntryExt, OpenOptionsExt};
+}
+
+cfg_docs! {
     /// Unix-specific extensions to `DirBuilder`.
     pub trait DirBuilderExt {
         /// Sets the mode to create new directories with. This option defaults to
@@ -67,7 +68,4 @@ cfg_if! {
         /// This options overwrites any previously set custom flags.
         fn custom_flags(&mut self, flags: i32) -> &mut Self;
     }
-    } else {
-        pub use std::os::unix::fs::{DirBuilderExt, OpenOptionsExt};
-    }
 }

src/os/unix/io.rs

@@ -1,9 +1,10 @@
 //! Unix-specific I/O extensions.
 
-use cfg_if::cfg_if;
+cfg_not_docs! {
+    pub use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+}
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_docs! {
     /// Raw file descriptors.
     pub type RawFd = std::os::raw::c_int;
 
@@ -50,7 +51,4 @@ cfg_if! {
         /// and must close the descriptor once it's no longer needed.
         fn into_raw_fd(self) -> RawFd;
     }
-    } else {
-        pub use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
-    }
 }

src/os/unix/net/mod.rs

@@ -1,7 +1,5 @@
 //! Unix-specific networking extensions.
 
-use cfg_if::cfg_if;
-
 pub use datagram::UnixDatagram;
 pub use listener::{Incoming, UnixListener};
 pub use stream::UnixStream;
@@ -10,8 +8,11 @@ mod datagram;
 mod listener;
 mod stream;
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_not_docs! {
+    pub use std::os::unix::net::SocketAddr;
+}
+
+cfg_docs! {
     use std::fmt;
 
     use crate::path::Path;
@@ -93,7 +94,4 @@ cfg_if! {
             unreachable!("this impl only appears in the rendered docs")
         }
     }
-    } else {
-        pub use std::os::unix::net::SocketAddr;
-    }
 }

src/os/windows/io.rs

@@ -1,9 +1,12 @@
 //! Windows-specific I/O extensions.
 
-use cfg_if::cfg_if;
+cfg_not_docs! {
+    pub use std::os::windows::io::{
+        AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle, RawSocket,
+    };
+}
 
-cfg_if! {
-    if #[cfg(feature = "docs")] {
+cfg_docs! {
     /// Raw HANDLEs.
     pub type RawHandle = *mut std::os::raw::c_void;
 
@@ -42,9 +45,4 @@ cfg_if! {
         /// it once it's no longer needed.
         fn into_raw_handle(self) -> RawHandle;
     }
-    } else {
-        pub use std::os::windows::io::{
-            AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle, RawSocket,
-        };
-    }
 }

src/prelude.rs

@@ -11,8 +11,6 @@
 //! use async_std::prelude::*;
 //! ```
 
-use cfg_if::cfg_if;
-
 #[doc(no_inline)]
 pub use crate::future::Future;
 #[doc(no_inline)]
@@ -41,12 +39,9 @@ pub use crate::io::write::WriteExt as _;
 #[doc(hidden)]
 pub use crate::stream::stream::StreamExt as _;
 
-cfg_if! {
-    if #[cfg(any(feature = "unstable", feature = "docs"))] {
+cfg_unstable! {
     #[doc(no_inline)]
     pub use crate::stream::DoubleEndedStream;
-
     #[doc(no_inline)]
     pub use crate::stream::ExactSizeStream;
-    }
 }

src/stream/double_ended_stream.rs

@@ -10,8 +10,8 @@ use std::task::{Context, Poll};
 /// `Item`s from the back, as well as the front.
 ///
 /// [`Stream`]: trait.Stream.html
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[cfg(any(feature = "unstable", feature = "docs"))]
 pub trait DoubleEndedStream: Stream {
     /// Removes and returns an element from the end of the stream.
     ///

src/stream/exact_size_stream.rs

@@ -76,8 +76,8 @@ pub use crate::stream::Stream;
 /// # });
 /// # }
 /// ```
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[cfg(any(feature = "unstable", feature = "docs"))]
 pub trait ExactSizeStream: Stream {
     /// Returns the exact number of times the stream will iterate.
     ///

src/stream/extend.rs

@@ -27,6 +27,7 @@ use crate::stream::IntoStream;
 /// #
 /// # }) }
 /// ```
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 pub trait Extend<A> {
     /// Extends a collection with the contents of a stream.

src/stream/from_stream.rs

@@ -106,8 +106,8 @@ use std::pin::Pin;
 ///```
 ///
 /// [`IntoStream`]: trait.IntoStream.html
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[cfg(any(feature = "unstable", feature = "docs"))]
 pub trait FromStream<T> {
     /// Creates a value from a stream.
     ///

src/stream/fused_stream.rs

@@ -14,7 +14,7 @@ use crate::stream::Stream;
 /// [`None`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.None
 /// [`Stream::fuse`]: trait.Stream.html#method.fuse
 /// [`Fuse`]: struct.Fuse.html
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 pub trait FusedStream: Stream {}
 

src/stream/interval.rs

@@ -43,9 +43,8 @@ use futures_timer::Delay;
 /// #
 /// # Ok(()) }) }
 /// ```
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[doc(inline)]
 pub fn interval(dur: Duration) -> Interval {
     Interval {
         delay: Delay::new(dur),
@@ -55,9 +54,9 @@ pub fn interval(dur: Duration) -> Interval {
 
 /// A stream representing notifications at fixed interval
 ///
-#[derive(Debug)]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[doc(inline)]
+#[derive(Debug)]
 pub struct Interval {
     delay: Delay,
     interval: Duration,

src/stream/into_stream.rs

@@ -13,8 +13,8 @@ use crate::stream::Stream;
 /// See also: [`FromStream`].
 ///
 /// [`FromStream`]: trait.FromStream.html
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[cfg(any(feature = "unstable", feature = "docs"))]
 pub trait IntoStream {
     /// The type of the elements being iterated over.
     type Item;

src/stream/mod.rs

@@ -21,8 +21,6 @@
 //! # })
 //! ```
 
-use cfg_if::cfg_if;
-
 pub use empty::{empty, Empty};
 pub use from_fn::{from_fn, FromFn};
 pub use once::{once, Once};
@@ -40,8 +38,7 @@ mod once;
 mod repeat;
 mod repeat_with;
 
-cfg_if! {
-    if #[cfg(any(feature = "unstable", feature = "docs"))] {
+cfg_unstable! {
     mod double_ended_stream;
     mod exact_size_stream;
     mod extend;
@@ -60,8 +57,6 @@ cfg_if! {
     pub use interval::{interval, Interval};
     pub use into_stream::IntoStream;
     pub use product::Product;
-        pub use sum::Sum;
-
     pub use stream::Merge;
-    }
+    pub use sum::Sum;
 }

src/stream/product.rs

@@ -11,8 +11,8 @@ use crate::stream::Stream;
 /// [`product`]: trait.Product.html#tymethod.product
 /// [`FromStream`]: trait.FromStream.html
 /// [`Stream::product`]: trait.Stream.html#method.product
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[cfg(any(feature = "unstable", feature = "docs"))]
 pub trait Product<A = Self>: Sized {
     /// Method which takes a stream and generates `Self` from the elements by
     /// multiplying the items.

src/stream/stream/merge.rs

@@ -8,7 +8,7 @@ use futures_core::Stream;
 /// This stream is returned by [`Stream::merge`].
 ///
 /// [`Stream::merge`]: trait.Stream.html#method.merge
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[derive(Debug)]
 pub struct Merge<L, R> {

src/stream/stream/mod.rs

@@ -91,32 +91,22 @@ pub use zip::Zip;
 use std::cmp::Ordering;
 use std::marker::PhantomData;
 
-use cfg_if::cfg_if;
-
-use crate::utils::extension_trait;
-
-cfg_if! {
-    if #[cfg(feature = "docs")] {
-        use std::ops::{Deref, DerefMut};
-
-        use crate::task::{Context, Poll};
-    }
-}
-
-cfg_if! {
-    if #[cfg(any(feature = "unstable", feature = "docs"))] {
-        mod merge;
-
+cfg_unstable! {
     use std::pin::Pin;
 
     use crate::future::Future;
     use crate::stream::FromStream;
 
     pub use merge::Merge;
-    }
+
+    mod merge;
 }
 
 extension_trait! {
+    use std::ops::{Deref, DerefMut};
+
+    use crate::task::{Context, Poll};
+
     #[doc = r#"
         An asynchronous stream of values.
 
@@ -1276,7 +1266,7 @@ extension_trait! {
 
             [`stream`]: trait.Stream.html#tymethod.next
         "#]
-        #[cfg(any(feature = "unstable", feature = "docs"))]
+        #[cfg(feature = "unstable")]
         #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
         #[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead (TODO)"]
         fn collect<'a, B>(
@@ -1315,7 +1305,7 @@ extension_trait! {
             # });
             ```
         "#]
-        #[cfg(any(feature = "unstable", feature = "docs"))]
+        #[cfg(feature = "unstable")]
         #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
         fn merge<U>(self, other: U) -> Merge<Self, U>
         where

src/stream/sum.rs

@@ -11,8 +11,8 @@ use crate::stream::Stream;
 /// [`sum`]: trait.Sum.html#tymethod.sum
 /// [`FromStream`]: trait.FromStream.html
 /// [`Stream::sum`]: trait.Stream.html#method.sum
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-#[cfg(any(feature = "unstable", feature = "docs"))]
 pub trait Sum<A = Self>: Sized {
     /// Method which takes a stream and generates `Self` from the elements by
     /// "summing up" the items.

src/sync/barrier.rs

@@ -32,6 +32,7 @@ use crate::sync::Mutex;
 /// # });
 /// # }
 /// ```
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[derive(Debug)]
 pub struct Barrier {
@@ -61,6 +62,7 @@ struct BarrierState {
 /// let barrier = Barrier::new(1);
 /// let barrier_wait_result = barrier.wait();
 /// ```
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[derive(Debug, Clone)]
 pub struct BarrierWaitResult(bool);

src/sync/mod.rs

@@ -32,14 +32,13 @@
 #[doc(inline)]
 pub use std::sync::{Arc, Weak};
 
-#[cfg(any(feature = "unstable", feature = "docs"))]
-pub use barrier::{Barrier, BarrierWaitResult};
-
 pub use mutex::{Mutex, MutexGuard};
 pub use rwlock::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 
-#[cfg(any(feature = "unstable", feature = "docs"))]
-#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
-mod barrier;
 mod mutex;
 mod rwlock;
+
+cfg_unstable! {
+    pub use barrier::{Barrier, BarrierWaitResult};
+    mod barrier;
+}

src/task/mod.rs

@@ -143,11 +143,9 @@ mod worker;
 
 pub(crate) mod blocking;
 
-cfg_if::cfg_if! {
-    if #[cfg(any(feature = "unstable", feature = "docs"))] {
+cfg_unstable! {
     mod yield_now;
     pub use yield_now::yield_now;
-    }
 }
 
 /// Spawns a blocking task.
@@ -178,7 +176,7 @@ cfg_if::cfg_if! {
 /// ```
 // Once this function stabilizes we should merge `blocking::spawn` into this so
 // all code in our crate uses `task::blocking` too.
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[inline]
 pub fn spawn_blocking<F, R>(f: F) -> task::JoinHandle<R>

src/task/yield_now.rs

@@ -26,7 +26,7 @@ use std::pin::Pin;
 /// #
 /// # }) }
 /// ```
-#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg(feature = "unstable")]
 #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
 #[inline]
 pub async fn yield_now() {

src/utils.rs

@@ -20,6 +20,64 @@ pub fn abort_on_panic<T>(f: impl FnOnce() -> T) -> T {
     t
 }
 
+/// Declares unstable items.
+#[doc(hidden)]
+macro_rules! cfg_unstable {
+    ($($item:item)*) => {
+        $(
+            #[cfg(feature = "unstable")]
+            #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
+            $item
+        )*
+    }
+}
+
+/// Declares Unix-specific items.
+#[doc(hidden)]
+macro_rules! cfg_unix {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(unix, feature = "docs"))]
+            #[cfg_attr(feature = "docs", doc(cfg(unix)))]
+            $item
+        )*
+    }
+}
+
+/// Declares Windows-specific items.
+#[doc(hidden)]
+macro_rules! cfg_windows {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(windows, feature = "docs"))]
+            #[cfg_attr(feature = "docs", doc(cfg(windows)))]
+            $item
+        )*
+    }
+}
+
+/// Declares items when the "docs" feature is enabled.
+#[doc(hidden)]
+macro_rules! cfg_docs {
+    ($($item:item)*) => {
+        $(
+            #[cfg(feature = "docs")]
+            $item
+        )*
+    }
+}
+
+/// Declares items when the "docs" feature is disabled.
+#[doc(hidden)]
+macro_rules! cfg_not_docs {
+    ($($item:item)*) => {
+        $(
+            #[cfg(not(feature = "docs"))]
+            $item
+        )*
+    }
+}
+
 /// Defines an extension trait for a base trait.
 ///
 /// In generated docs, the base trait will contain methods from the extension trait. In actual
@@ -29,7 +87,6 @@ pub fn abort_on_panic<T>(f: impl FnOnce() -> T) -> T {
 /// Inside invocations of this macro, we write a definitions that looks similar to the final
 /// rendered docs, and the macro then generates all the boilerplate for us.
 #[doc(hidden)]
-#[macro_export]
 macro_rules! extension_trait {
     (
         // Interesting patterns:
@@ -113,6 +170,12 @@ macro_rules! extension_trait {
     // Handle the end of the token list.
     (@doc ($($head:tt)*)) => { $($head)* };
     (@ext ($($head:tt)*)) => { $($head)* };
-}
 
-pub use crate::extension_trait;
+    // Parse imports at the beginning of the macro.
+    ($import:item $($tail:tt)*) => {
+        #[cfg(feature = "docs")]
+        $import
+
+        extension_trait!($($tail)*);
+    };
+}