Merge pull request #1006 from nnethercote/rm-extension_trait

Remove `extension_trait`

src/io/seek/mod.rs

@@ -4,117 +4,47 @@ use seek::SeekFuture;
 
 use crate::io::SeekFrom;
 
-extension_trait! {
-    use std::ops::{Deref, DerefMut};
-    use std::pin::Pin;
+pub use futures_io::AsyncSeek as Seek;
 
-    use crate::io;
-    use crate::task::{Context, Poll};
+#[doc = r#"
+    Extension methods for [`Seek`].
 
+    [`Seek`]: ../trait.Seek.html
+"#]
+pub trait SeekExt: Seek {
     #[doc = r#"
-        Allows seeking through a byte stream.
+        Seeks to a new position in a byte stream.
 
-        This trait is a re-export of [`futures::io::AsyncSeek`] and is an async version of
-        [`std::io::Seek`].
+        Returns the new position in the byte stream.
 
-        The [provided methods] do not really exist in the trait itself, but they become
-        available when [`SeekExt`] the [prelude] is imported:
+        A seek beyond the end of stream is allowed, but behavior is defined by the
+        implementation.
 
-        ```
-        # #[allow(unused_imports)]
+        # Examples
+
+        ```no_run
+        # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
+        #
+        use async_std::fs::File;
+        use async_std::io::SeekFrom;
         use async_std::prelude::*;
-        ```
 
-        [`std::io::Seek`]: https://doc.rust-lang.org/std/io/trait.Seek.html
-        [`futures::io::AsyncSeek`]:
-        https://docs.rs/futures/0.3/futures/io/trait.AsyncSeek.html
-        [provided methods]: #provided-methods
-        [`SeekExt`]: ../io/prelude/trait.SeekExt.html
-        [prelude]: ../prelude/index.html
-    "#]
-    pub trait Seek {
-        #[doc = r#"
-            Attempt to seek to an offset, in bytes, in a stream.
-        "#]
-        fn poll_seek(
-            self: Pin<&mut Self>,
-            cx: &mut Context<'_>,
-            pos: SeekFrom,
-        ) -> Poll<io::Result<u64>>;
-    }
+        let mut file = File::open("a.txt").await?;
 
-    #[doc = r#"
-        Extension methods for [`Seek`].
-
-        [`Seek`]: ../trait.Seek.html
+        let file_len = file.seek(SeekFrom::End(0)).await?;
+        #
+        # Ok(()) }) }
+        ```
     "#]
-    pub trait SeekExt: futures_io::AsyncSeek {
-        #[doc = r#"
-            Seeks to a new position in a byte stream.
-
-            Returns the new position in the byte stream.
-
-            A seek beyond the end of stream is allowed, but behavior is defined by the
-            implementation.
-
-            # Examples
-
-            ```no_run
-            # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
-            #
-            use async_std::fs::File;
-            use async_std::io::SeekFrom;
-            use async_std::prelude::*;
-
-            let mut file = File::open("a.txt").await?;
-
-            let file_len = file.seek(SeekFrom::End(0)).await?;
-            #
-            # Ok(()) }) }
-            ```
-        "#]
-        fn seek(
-            &mut self,
-            pos: SeekFrom,
-        ) -> impl Future<Output = io::Result<u64>> + '_ [SeekFuture<'_, Self>]
-        where
-            Self: Unpin,
-        {
-            SeekFuture { seeker: self, pos }
-        }
-    }
-
-    impl<T: Seek + Unpin + ?Sized> Seek for Box<T> {
-        fn poll_seek(
-            self: Pin<&mut Self>,
-            cx: &mut Context<'_>,
-            pos: SeekFrom,
-        ) -> Poll<io::Result<u64>> {
-            unreachable!("this impl only appears in the rendered docs")
-        }
-    }
-
-    impl<T: Seek + Unpin + ?Sized> Seek for &mut T {
-        fn poll_seek(
-            self: Pin<&mut Self>,
-            cx: &mut Context<'_>,
-            pos: SeekFrom,
-        ) -> Poll<io::Result<u64>> {
-            unreachable!("this impl only appears in the rendered docs")
-        }
-    }
-
-    impl<P> Seek for Pin<P>
+    fn seek(
+        &mut self,
+        pos: SeekFrom,
+    ) -> SeekFuture<'_, Self>
     where
-        P: DerefMut + Unpin,
-        <P as Deref>::Target: Seek,
+        Self: Unpin,
     {
-        fn poll_seek(
-            self: Pin<&mut Self>,
-            cx: &mut Context<'_>,
-            pos: SeekFrom,
-        ) -> Poll<io::Result<u64>> {
-            unreachable!("this impl only appears in the rendered docs")
-        }
+        SeekFuture { seeker: self, pos }
     }
 }
+
+impl<T: Seek + ?Sized> SeekExt for T {}