From 2074db4312b023c59d5b6ce31fbe9658e8d4e852 Mon Sep 17 00:00:00 2001
From: Taiki Endo <te316e89@gmail.com>
Date: Sat, 18 Dec 2021 22:54:32 +0900
Subject: [PATCH 1/2] Remove read-initializer feature

---
 futures-io/Cargo.toml                   |  1 -
 futures-io/src/lib.rs                   | 45 -------------------------
 futures-util/Cargo.toml                 |  1 -
 futures-util/src/compat/compat01as03.rs | 12 -------
 futures-util/src/compat/compat03as01.rs | 12 +------
 futures-util/src/future/either.rs       | 10 ------
 futures-util/src/io/allow_std.rs        | 11 ------
 futures-util/src/io/buf_reader.rs       |  8 -----
 futures-util/src/io/chain.rs            | 12 -------
 futures-util/src/io/empty.rs            |  8 -----
 futures-util/src/io/mod.rs              | 12 +------
 futures-util/src/io/repeat.rs           |  8 -----
 futures-util/src/io/take.rs             |  7 ----
 futures-util/src/lib.rs                 |  9 -----
 futures/Cargo.toml                      |  1 -
 futures/src/lib.rs                      |  4 ---
 16 files changed, 2 insertions(+), 159 deletions(-)

diff --git a/futures-io/Cargo.toml b/futures-io/Cargo.toml
index a3895b8057..f87c34a9c1 100644
--- a/futures-io/Cargo.toml
+++ b/futures-io/Cargo.toml
@@ -18,7 +18,6 @@ std = []
 # These features are outside of the normal semver guarantees and require the
 # `unstable` feature as an explicit opt-in to unstable API.
 unstable = []
-read-initializer = []
 
 [dependencies]
 
diff --git a/futures-io/src/lib.rs b/futures-io/src/lib.rs
index 7e03b8e5a0..e91eb78492 100644
--- a/futures-io/src/lib.rs
+++ b/futures-io/src/lib.rs
@@ -8,7 +8,6 @@
 //! All items of this library are only available when the `std` feature of this
 //! library is activated, and it is activated by default.
 
-#![cfg_attr(all(feature = "read-initializer", feature = "std"), feature(read_initializer))]
 #![cfg_attr(not(feature = "std"), no_std)]
 #![warn(missing_debug_implementations, missing_docs, rust_2018_idioms, unreachable_pub)]
 // It cannot be included in the published code because this lints have false positives in the minimum required version.
@@ -22,9 +21,6 @@
 ))]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 
-#[cfg(all(feature = "read-initializer", not(feature = "unstable")))]
-compile_error!("The `read-initializer` feature requires the `unstable` feature as an explicit opt-in to unstable features");
-
 #[cfg(feature = "std")]
 mod if_std {
     use std::io;
@@ -34,11 +30,6 @@ mod if_std {
 
     // Re-export some types from `std::io` so that users don't have to deal
     // with conflicts when `use`ing `futures::io` and `std::io`.
-    #[cfg(feature = "read-initializer")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "read-initializer")))]
-    #[doc(no_inline)]
-    #[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411
-    pub use io::Initializer;
     #[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411
     #[doc(no_inline)]
     pub use io::{Error, ErrorKind, IoSlice, IoSliceMut, Result, SeekFrom};
@@ -51,27 +42,6 @@ mod if_std {
     /// for wakeup and return if data is not yet available, rather than blocking
     /// the calling thread.
     pub trait AsyncRead {
-        /// Determines if this `AsyncRead`er can work with buffers of
-        /// uninitialized memory.
-        ///
-        /// The default implementation returns an initializer which will zero
-        /// buffers.
-        ///
-        /// This method is only available when the `read-initializer` feature of this
-        /// library is activated.
-        ///
-        /// # Safety
-        ///
-        /// This method is `unsafe` because an `AsyncRead`er could otherwise
-        /// return a non-zeroing `Initializer` from another `AsyncRead` type
-        /// without an `unsafe` block.
-        #[cfg(feature = "read-initializer")]
-        #[cfg_attr(docsrs, doc(cfg(feature = "read-initializer")))]
-        #[inline]
-        unsafe fn initializer(&self) -> Initializer {
-            Initializer::zeroing()
-        }
-
         /// Attempt to read from the `AsyncRead` into `buf`.
         ///
         /// On success, returns `Poll::Ready(Ok(num_bytes_read))`.
@@ -329,11 +299,6 @@ mod if_std {
 
     macro_rules! deref_async_read {
         () => {
-            #[cfg(feature = "read-initializer")]
-            unsafe fn initializer(&self) -> Initializer {
-                (**self).initializer()
-            }
-
             fn poll_read(
                 mut self: Pin<&mut Self>,
                 cx: &mut Context<'_>,
@@ -365,11 +330,6 @@ mod if_std {
         P: DerefMut + Unpin,
         P::Target: AsyncRead,
     {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn initializer(&self) -> Initializer {
-            (**self).initializer()
-        }
-
         fn poll_read(
             self: Pin<&mut Self>,
             cx: &mut Context<'_>,
@@ -389,11 +349,6 @@ mod if_std {
 
     macro_rules! delegate_async_read_to_stdio {
         () => {
-            #[cfg(feature = "read-initializer")]
-            unsafe fn initializer(&self) -> Initializer {
-                io::Read::initializer(self)
-            }
-
             fn poll_read(
                 mut self: Pin<&mut Self>,
                 _: &mut Context<'_>,
diff --git a/futures-util/Cargo.toml b/futures-util/Cargo.toml
index d1c165d349..cf559b6a4e 100644
--- a/futures-util/Cargo.toml
+++ b/futures-util/Cargo.toml
@@ -27,7 +27,6 @@ channel = ["std", "futures-channel"]
 # `unstable` feature as an explicit opt-in to unstable API.
 unstable = []
 bilock = []
-read-initializer = ["io", "futures-io/read-initializer", "futures-io/unstable"]
 write-all-vectored = ["io"]
 
 [dependencies]
diff --git a/futures-util/src/compat/compat01as03.rs b/futures-util/src/compat/compat01as03.rs
index 17239a4e57..754e3d82a1 100644
--- a/futures-util/src/compat/compat01as03.rs
+++ b/futures-util/src/compat/compat01as03.rs
@@ -351,8 +351,6 @@ unsafe impl UnsafeNotify01 for NotifyWaker {
 #[cfg_attr(docsrs, doc(cfg(feature = "io-compat")))]
 mod io {
     use super::*;
-    #[cfg(feature = "read-initializer")]
-    use futures_io::Initializer;
     use futures_io::{AsyncRead as AsyncRead03, AsyncWrite as AsyncWrite03};
     use std::io::Error;
     use tokio_io::{AsyncRead as AsyncRead01, AsyncWrite as AsyncWrite01};
@@ -416,16 +414,6 @@ mod io {
     impl<W: AsyncWrite01> AsyncWrite01CompatExt for W {}
 
     impl<R: AsyncRead01> AsyncRead03 for Compat01As03<R> {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn initializer(&self) -> Initializer {
-            // check if `prepare_uninitialized_buffer` needs zeroing
-            if self.inner.get_ref().prepare_uninitialized_buffer(&mut [1]) {
-                Initializer::zeroing()
-            } else {
-                Initializer::nop()
-            }
-        }
-
         fn poll_read(
             mut self: Pin<&mut Self>,
             cx: &mut Context<'_>,
diff --git a/futures-util/src/compat/compat03as01.rs b/futures-util/src/compat/compat03as01.rs
index 2573fe7a74..5d3a6e920b 100644
--- a/futures-util/src/compat/compat03as01.rs
+++ b/futures-util/src/compat/compat03as01.rs
@@ -236,17 +236,7 @@ mod io {
         }
     }
 
-    impl<R: AsyncRead03 + Unpin> AsyncRead01 for Compat<R> {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn prepare_uninitialized_buffer(&self, buf: &mut [u8]) -> bool {
-            let initializer = self.inner.initializer();
-            let does_init = initializer.should_initialize();
-            if does_init {
-                initializer.initialize(buf);
-            }
-            does_init
-        }
-    }
+    impl<R: AsyncRead03 + Unpin> AsyncRead01 for Compat<R> {}
 
     impl<W: AsyncWrite03 + Unpin> std::io::Write for Compat<W> {
         fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
diff --git a/futures-util/src/future/either.rs b/futures-util/src/future/either.rs
index 35650daa99..9602de7a42 100644
--- a/futures-util/src/future/either.rs
+++ b/futures-util/src/future/either.rs
@@ -184,8 +184,6 @@ mod if_std {
 
     use core::pin::Pin;
     use core::task::{Context, Poll};
-    #[cfg(feature = "read-initializer")]
-    use futures_io::Initializer;
     use futures_io::{
         AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, IoSlice, IoSliceMut, Result, SeekFrom,
     };
@@ -195,14 +193,6 @@ mod if_std {
         A: AsyncRead,
         B: AsyncRead,
     {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn initializer(&self) -> Initializer {
-            match self {
-                Either::Left(x) => x.initializer(),
-                Either::Right(x) => x.initializer(),
-            }
-        }
-
         fn poll_read(
             self: Pin<&mut Self>,
             cx: &mut Context<'_>,
diff --git a/futures-util/src/io/allow_std.rs b/futures-util/src/io/allow_std.rs
index 1d13e0c177..ec30ee31e5 100644
--- a/futures-util/src/io/allow_std.rs
+++ b/futures-util/src/io/allow_std.rs
@@ -1,6 +1,4 @@
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, IoSlice, IoSliceMut, SeekFrom};
 use std::pin::Pin;
 use std::{fmt, io};
@@ -121,10 +119,6 @@ where
     fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
         self.0.read_vectored(bufs)
     }
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        self.0.initializer()
-    }
     fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
         self.0.read_to_end(buf)
     }
@@ -155,11 +149,6 @@ where
     ) -> Poll<io::Result<usize>> {
         Poll::Ready(Ok(try_with_interrupt!(self.0.read_vectored(bufs))))
     }
-
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        self.0.initializer()
-    }
 }
 
 impl<T> io::Seek for AllowStdIo<T>
diff --git a/futures-util/src/io/buf_reader.rs b/futures-util/src/io/buf_reader.rs
index c4cdbe8947..2a7e5005cd 100644
--- a/futures-util/src/io/buf_reader.rs
+++ b/futures-util/src/io/buf_reader.rs
@@ -2,8 +2,6 @@ use super::DEFAULT_BUF_SIZE;
 use futures_core::future::Future;
 use futures_core::ready;
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, IoSliceMut, SeekFrom};
 use pin_project_lite::pin_project;
 use std::io::{self, Read};
@@ -141,12 +139,6 @@ impl<R: AsyncRead> AsyncRead for BufReader<R> {
         self.consume(nread);
         Poll::Ready(Ok(nread))
     }
-
-    // we can't skip unconditionally because of the large buffer case in read.
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        self.inner.initializer()
-    }
 }
 
 impl<R: AsyncRead> AsyncBufRead for BufReader<R> {
diff --git a/futures-util/src/io/chain.rs b/futures-util/src/io/chain.rs
index a35c50de35..728a3d2dc0 100644
--- a/futures-util/src/io/chain.rs
+++ b/futures-util/src/io/chain.rs
@@ -1,7 +1,5 @@
 use futures_core::ready;
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead, IoSliceMut};
 use pin_project_lite::pin_project;
 use std::fmt;
@@ -111,16 +109,6 @@ where
         }
         this.second.poll_read_vectored(cx, bufs)
     }
-
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        let initializer = self.first.initializer();
-        if initializer.should_initialize() {
-            initializer
-        } else {
-            self.second.initializer()
-        }
-    }
 }
 
 impl<T, U> AsyncBufRead for Chain<T, U>
diff --git a/futures-util/src/io/empty.rs b/futures-util/src/io/empty.rs
index ab2395a8af..02f6103f54 100644
--- a/futures-util/src/io/empty.rs
+++ b/futures-util/src/io/empty.rs
@@ -1,6 +1,4 @@
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead};
 use std::fmt;
 use std::io;
@@ -43,12 +41,6 @@ impl AsyncRead for Empty {
     ) -> Poll<io::Result<usize>> {
         Poll::Ready(Ok(0))
     }
-
-    #[cfg(feature = "read-initializer")]
-    #[inline]
-    unsafe fn initializer(&self) -> Initializer {
-        Initializer::nop()
-    }
 }
 
 impl AsyncBufRead for Empty {
diff --git a/futures-util/src/io/mod.rs b/futures-util/src/io/mod.rs
index bb576c0245..c89ba8af15 100644
--- a/futures-util/src/io/mod.rs
+++ b/futures-util/src/io/mod.rs
@@ -26,10 +26,6 @@ use std::{pin::Pin, ptr};
 // Re-export some types from `std::io` so that users don't have to deal
 // with conflicts when `use`ing `futures::io` and `std::io`.
 #[doc(no_inline)]
-#[cfg(feature = "read-initializer")]
-#[cfg_attr(docsrs, doc(cfg(feature = "read-initializer")))]
-pub use std::io::Initializer;
-#[doc(no_inline)]
 pub use std::io::{Error, ErrorKind, IoSlice, IoSliceMut, Result, SeekFrom};
 
 pub use futures_io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite};
@@ -40,15 +36,9 @@ const DEFAULT_BUF_SIZE: usize = 8 * 1024;
 
 /// Initializes a buffer if necessary.
 ///
-/// A buffer is always initialized if `read-initializer` feature is disabled.
+/// A buffer is currently always initialized.
 #[inline]
 unsafe fn initialize<R: AsyncRead>(_reader: &R, buf: &mut [u8]) {
-    #[cfg(feature = "read-initializer")]
-    {
-        if !_reader.initializer().should_initialize() {
-            return;
-        }
-    }
     ptr::write_bytes(buf.as_mut_ptr(), 0, buf.len())
 }
 
diff --git a/futures-util/src/io/repeat.rs b/futures-util/src/io/repeat.rs
index 4cefcb2a28..2828bf0114 100644
--- a/futures-util/src/io/repeat.rs
+++ b/futures-util/src/io/repeat.rs
@@ -1,7 +1,5 @@
 use futures_core::ready;
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncRead, IoSliceMut};
 use std::fmt;
 use std::io;
@@ -59,12 +57,6 @@ impl AsyncRead for Repeat {
         }
         Poll::Ready(Ok(nwritten))
     }
-
-    #[cfg(feature = "read-initializer")]
-    #[inline]
-    unsafe fn initializer(&self) -> Initializer {
-        Initializer::nop()
-    }
 }
 
 impl fmt::Debug for Repeat {
diff --git a/futures-util/src/io/take.rs b/futures-util/src/io/take.rs
index 05830203d0..2c494804d9 100644
--- a/futures-util/src/io/take.rs
+++ b/futures-util/src/io/take.rs
@@ -1,7 +1,5 @@
 use futures_core::ready;
 use futures_core::task::{Context, Poll};
-#[cfg(feature = "read-initializer")]
-use futures_io::Initializer;
 use futures_io::{AsyncBufRead, AsyncRead};
 use pin_project_lite::pin_project;
 use std::pin::Pin;
@@ -100,11 +98,6 @@ impl<R: AsyncRead> AsyncRead for Take<R> {
         *this.limit -= n as u64;
         Poll::Ready(Ok(n))
     }
-
-    #[cfg(feature = "read-initializer")]
-    unsafe fn initializer(&self) -> Initializer {
-        self.inner.initializer()
-    }
 }
 
 impl<R: AsyncBufRead> AsyncBufRead for Take<R> {
diff --git a/futures-util/src/lib.rs b/futures-util/src/lib.rs
index c2b71c122f..32cfe23475 100644
--- a/futures-util/src/lib.rs
+++ b/futures-util/src/lib.rs
@@ -1,7 +1,6 @@
 //! Combinators and utilities for working with `Future`s, `Stream`s, `Sink`s,
 //! and the `AsyncRead` and `AsyncWrite` traits.
 
-#![cfg_attr(feature = "read-initializer", feature(read_initializer))]
 #![cfg_attr(feature = "write-all-vectored", feature(io_slice_advance))]
 #![cfg_attr(not(feature = "std"), no_std)]
 #![warn(
@@ -24,9 +23,6 @@
 #[cfg(all(feature = "bilock", not(feature = "unstable")))]
 compile_error!("The `bilock` feature requires the `unstable` feature as an explicit opt-in to unstable features");
 
-#[cfg(all(feature = "read-initializer", not(feature = "unstable")))]
-compile_error!("The `read-initializer` feature requires the `unstable` feature as an explicit opt-in to unstable features");
-
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
@@ -149,11 +145,6 @@ macro_rules! delegate_async_write {
 #[cfg(feature = "std")]
 macro_rules! delegate_async_read {
     ($field:ident) => {
-        #[cfg(feature = "read-initializer")]
-        unsafe fn initializer(&self) -> $crate::io::Initializer {
-            self.$field.initializer()
-        }
-
         fn poll_read(
             self: core::pin::Pin<&mut Self>,
             cx: &mut core::task::Context<'_>,
diff --git a/futures/Cargo.toml b/futures/Cargo.toml
index 5e4200f565..f01e99f10e 100644
--- a/futures/Cargo.toml
+++ b/futures/Cargo.toml
@@ -47,7 +47,6 @@ thread-pool = ["executor", "futures-executor/thread-pool"]
 # `unstable` feature as an explicit opt-in to unstable API.
 unstable = ["futures-io/unstable", "futures-util/unstable"]
 bilock = ["futures-util/bilock"]
-read-initializer = ["futures-io/read-initializer", "futures-util/read-initializer"]
 write-all-vectored = ["futures-util/write-all-vectored"]
 
 [package.metadata.docs.rs]
diff --git a/futures/src/lib.rs b/futures/src/lib.rs
index 6317576b25..7e90b3b63d 100644
--- a/futures/src/lib.rs
+++ b/futures/src/lib.rs
@@ -78,7 +78,6 @@
 //! The majority of examples and code snippets in this crate assume that they are
 //! inside an async block as written above.
 
-#![cfg_attr(feature = "read-initializer", feature(read_initializer))]
 #![cfg_attr(not(feature = "std"), no_std)]
 #![warn(
     missing_debug_implementations,
@@ -99,9 +98,6 @@
 #[cfg(all(feature = "bilock", not(feature = "unstable")))]
 compile_error!("The `bilock` feature requires the `unstable` feature as an explicit opt-in to unstable features");
 
-#[cfg(all(feature = "read-initializer", not(feature = "unstable")))]
-compile_error!("The `read-initializer` feature requires the `unstable` feature as an explicit opt-in to unstable features");
-
 #[doc(no_inline)]
 pub use futures_core::future::{Future, TryFuture};
 #[doc(no_inline)]

From 8df0fc3ae84add9d60c434cac08020ccb71150e1 Mon Sep 17 00:00:00 2001
From: Taiki Endo <te316e89@gmail.com>
Date: Sat, 18 Dec 2021 22:59:07 +0900
Subject: [PATCH 2/2] Fix clippy::return_self_not_must_use warning

```text
error: missing `#[must_use]` attribute on a method returning `Self`
  --> futures-util/src/stream/select_with_strategy.rs:19:5
   |
19 | /     pub fn toggle(&mut self) -> Self {
20 | |         let old = *self;
21 | |
22 | |         match self {
...  |
27 | |         old
28 | |     }
   | |_____^
   |
```
---
 futures-util/src/stream/select_with_strategy.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/futures-util/src/stream/select_with_strategy.rs b/futures-util/src/stream/select_with_strategy.rs
index bd86990cdb..2673a4c2bd 100644
--- a/futures-util/src/stream/select_with_strategy.rs
+++ b/futures-util/src/stream/select_with_strategy.rs
@@ -16,6 +16,7 @@ pub enum PollNext {
 
 impl PollNext {
     /// Toggle the value and return the old one.
+    #[must_use]
     pub fn toggle(&mut self) -> Self {
         let old = *self;