Rollup merge of #93613 - crlf0710:rename_to_async_iter, r=yaahc

Move `{core,std}::stream::Stream` to `{core,std}::async_iter::AsyncIterator`

Following amendments in https://github.com/rust-lang/rfcs/pull/3208/.

cc #79024
cc ``@yoshuawuyts`` ``@joshtriplett``

8 files changed, 83 insertions, 84 deletions

diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index aa7344ba405..68bf59a01b3 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -133,6 +133,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use core::any::Any;
+use core::async_iter::AsyncIterator;
 use core::borrow;
 use core::cmp::Ordering;
 use core::convert::{From, TryFrom};
@@ -149,7 +150,6 @@ use core::ops::{
 };
 use core::pin::Pin;
 use core::ptr::{self, Unique};
-use core::stream::Stream;
 use core::task::{Context, Poll};
 
 #[cfg(not(no_global_oom_handling))]
@@ -1992,8 +1992,8 @@ where
     }
 }
 
-#[unstable(feature = "async_stream", issue = "79024")]
-impl<S: ?Sized + Stream + Unpin> Stream for Box<S> {
+#[unstable(feature = "async_iterator", issue = "79024")]
+impl<S: ?Sized + AsyncIterator + Unpin> AsyncIterator for Box<S> {
     type Item = S::Item;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index ce75859f963..6da32df57ef 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -91,7 +91,7 @@
 #![feature(array_chunks)]
 #![feature(array_methods)]
 #![feature(array_windows)]
-#![feature(async_stream)]
+#![feature(async_iterator)]
 #![feature(coerce_unsized)]
 #![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))]
 #![feature(const_box)]
diff --git a/library/core/src/stream/stream.rs b/library/core/src/async_iter/async_iter.rs
index 2cfddf9ad01..f29de31171a 100644
--- a/library/core/src/stream/stream.rs
+++ b/library/core/src/async_iter/async_iter.rs
@@ -4,50 +4,50 @@ use crate::task::{Context, Poll};
 
 /// An interface for dealing with asynchronous iterators.
 ///
-/// This is the main stream trait. For more about the concept of streams
+/// This is the main async iterator trait. For more about the concept of async iterators
 /// generally, please see the [module-level documentation]. In particular, you
-/// may want to know how to [implement `Stream`][impl].
+/// may want to know how to [implement `AsyncIterator`][impl].
 ///
 /// [module-level documentation]: index.html
-/// [impl]: index.html#implementing-stream
-#[unstable(feature = "async_stream", issue = "79024")]
-#[must_use = "streams do nothing unless polled"]
-pub trait Stream {
-    /// The type of items yielded by the stream.
+/// [impl]: index.html#implementing-async-iterator
+#[unstable(feature = "async_iterator", issue = "79024")]
+#[must_use = "async iterators do nothing unless polled"]
+pub trait AsyncIterator {
+    /// The type of items yielded by the async iterator.
     type Item;
 
-    /// Attempt to pull out the next value of this stream, registering the
+    /// Attempt to pull out the next value of this async iterator, registering the
     /// current task for wakeup if the value is not yet available, and returning
-    /// `None` if the stream is exhausted.
+    /// `None` if the async iterator is exhausted.
     ///
     /// # Return value
     ///
     /// There are several possible return values, each indicating a distinct
-    /// stream state:
+    /// async iterator state:
     ///
-    /// - `Poll::Pending` means that this stream's next value is not ready
+    /// - `Poll::Pending` means that this async iterator's next value is not ready
     /// yet. Implementations will ensure that the current task will be notified
     /// when the next value may be ready.
     ///
-    /// - `Poll::Ready(Some(val))` means that the stream has successfully
+    /// - `Poll::Ready(Some(val))` means that the async iterator has successfully
     /// produced a value, `val`, and may produce further values on subsequent
     /// `poll_next` calls.
     ///
-    /// - `Poll::Ready(None)` means that the stream has terminated, and
+    /// - `Poll::Ready(None)` means that the async iterator has terminated, and
     /// `poll_next` should not be invoked again.
     ///
     /// # Panics
     ///
-    /// Once a stream has finished (returned `Ready(None)` from `poll_next`), calling its
+    /// Once an async iterator has finished (returned `Ready(None)` from `poll_next`), calling its
     /// `poll_next` method again may panic, block forever, or cause other kinds of
-    /// problems; the `Stream` trait places no requirements on the effects of
+    /// problems; the `AsyncIterator` trait places no requirements on the effects of
     /// such a call. However, as the `poll_next` method is not marked `unsafe`,
     /// Rust's usual rules apply: calls must never cause undefined behavior
     /// (memory corruption, incorrect use of `unsafe` functions, or the like),
-    /// regardless of the stream's state.
+    /// regardless of the async iterator's state.
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>;
 
-    /// Returns the bounds on the remaining length of the stream.
+    /// Returns the bounds on the remaining length of the async iterator.
     ///
     /// Specifically, `size_hint()` returns a tuple where the first element
     /// is the lower bound, and the second element is the upper bound.
@@ -58,12 +58,12 @@ pub trait Stream {
     ///
     /// # Implementation notes
     ///
-    /// It is not enforced that a stream implementation yields the declared
-    /// number of elements. A buggy stream may yield less than the lower bound
+    /// It is not enforced that an async iterator implementation yields the declared
+    /// number of elements. A buggy async iterator may yield less than the lower bound
     /// or more than the upper bound of elements.
     ///
     /// `size_hint()` is primarily intended to be used for optimizations such as
-    /// reserving space for the elements of the stream, but must not be
+    /// reserving space for the elements of the async iterator, but must not be
     /// trusted to e.g., omit bounds checks in unsafe code. An incorrect
     /// implementation of `size_hint()` should not lead to memory safety
     /// violations.
@@ -72,15 +72,15 @@ pub trait Stream {
     /// because otherwise it would be a violation of the trait's protocol.
     ///
     /// The default implementation returns <code>(0, [None])</code> which is correct for any
-    /// stream.
+    /// async iterator.
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
         (0, None)
     }
 }
 
-#[unstable(feature = "async_stream", issue = "79024")]
-impl<S: ?Sized + Stream + Unpin> Stream for &mut S {
+#[unstable(feature = "async_iterator", issue = "79024")]
+impl<S: ?Sized + AsyncIterator + Unpin> AsyncIterator for &mut S {
     type Item = S::Item;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
@@ -92,16 +92,16 @@ impl<S: ?Sized + Stream + Unpin> Stream for &mut S {
     }
 }
 
-#[unstable(feature = "async_stream", issue = "79024")]
-impl<P> Stream for Pin<P>
+#[unstable(feature = "async_iterator", issue = "79024")]
+impl<P> AsyncIterator for Pin<P>
 where
     P: DerefMut,
-    P::Target: Stream,
+    P::Target: AsyncIterator,
 {
-    type Item = <P::Target as Stream>::Item;
+    type Item = <P::Target as AsyncIterator>::Item;
 
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
-        <P::Target as Stream>::poll_next(self.as_deref_mut(), cx)
+        <P::Target as AsyncIterator>::poll_next(self.as_deref_mut(), cx)
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
diff --git a/library/core/src/stream/from_iter.rs b/library/core/src/async_iter/from_iter.rs
index eb9a0fd2842..3180187afc8 100644
--- a/library/core/src/stream/from_iter.rs
+++ b/library/core/src/async_iter/from_iter.rs
@@ -1,31 +1,31 @@
 use crate::pin::Pin;
 
-use crate::stream::Stream;
+use crate::async_iter::AsyncIterator;
 use crate::task::{Context, Poll};
 
-/// A stream that was created from iterator.
+/// An async iterator that was created from iterator.
 ///
-/// This stream is created by the [`from_iter`] function.
+/// This async iterator is created by the [`from_iter`] function.
 /// See it documentation for more.
 ///
 /// [`from_iter`]: fn.from_iter.html
-#[unstable(feature = "stream_from_iter", issue = "81798")]
+#[unstable(feature = "async_iter_from_iter", issue = "81798")]
 #[derive(Clone, Debug)]
 pub struct FromIter<I> {
     iter: I,
 }
 
-#[unstable(feature = "stream_from_iter", issue = "81798")]
+#[unstable(feature = "async_iter_from_iter", issue = "81798")]
 impl<I> Unpin for FromIter<I> {}
 
-/// Converts an iterator into a stream.
-#[unstable(feature = "stream_from_iter", issue = "81798")]
+/// Converts an iterator into an async iterator.
+#[unstable(feature = "async_iter_from_iter", issue = "81798")]
 pub fn from_iter<I: IntoIterator>(iter: I) -> FromIter<I::IntoIter> {
     FromIter { iter: iter.into_iter() }
 }
 
-#[unstable(feature = "stream_from_iter", issue = "81798")]
-impl<I: Iterator> Stream for FromIter<I> {
+#[unstable(feature = "async_iter_from_iter", issue = "81798")]
+impl<I: Iterator> AsyncIterator for FromIter<I> {
     type Item = I::Item;
 
     fn poll_next(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
diff --git a/library/core/src/stream/mod.rs b/library/core/src/async_iter/mod.rs
index b59a46d5f3a..0c6f637711b 100644
--- a/library/core/src/stream/mod.rs
+++ b/library/core/src/async_iter/mod.rs
@@ -1,10 +1,9 @@
 //! Composable asynchronous iteration.
 //!
-//! If futures are asynchronous values, then streams are asynchronous
-//! iterators. If you've found yourself with an asynchronous collection of some kind,
+//! If you've found yourself with an asynchronous collection of some kind,
 //! and needed to perform an operation on the elements of said collection,
-//! you'll quickly run into 'streams'. Streams are heavily used in idiomatic
-//! asynchronous Rust code, so it's worth becoming familiar with them.
+//! you'll quickly run into 'async iterators'. Async Iterators are heavily used in
+//! idiomatic asynchronous Rust code, so it's worth becoming familiar with them.
 //!
 //! Before explaining more, let's talk about how this module is structured:
 //!
@@ -12,71 +11,71 @@
 //!
 //! This module is largely organized by type:
 //!
-//! * [Traits] are the core portion: these traits define what kind of streams
+//! * [Traits] are the core portion: these traits define what kind of async iterators
 //!   exist and what you can do with them. The methods of these traits are worth
 //!   putting some extra study time into.
-//! * Functions provide some helpful ways to create some basic streams.
+//! * Functions provide some helpful ways to create some basic async iterators.
 //! * Structs are often the return types of the various methods on this
 //!   module's traits. You'll usually want to look at the method that creates
 //!   the `struct`, rather than the `struct` itself. For more detail about why,
-//!   see '[Implementing Stream](#implementing-stream)'.
+//!   see '[Implementing Async Iterator](#implementing-async-iterator)'.
 //!
 //! [Traits]: #traits
 //!
-//! That's it! Let's dig into streams.
+//! That's it! Let's dig into async iterators.
 //!
-//! # Stream
+//! # Async Iterators
 //!
-//! The heart and soul of this module is the [`Stream`] trait. The core of
-//! [`Stream`] looks like this:
+//! The heart and soul of this module is the [`AsyncIterator`] trait. The core of
+//! [`AsyncIterator`] looks like this:
 //!
 //! ```
 //! # use core::task::{Context, Poll};
 //! # use core::pin::Pin;
-//! trait Stream {
+//! trait AsyncIterator {
 //!     type Item;
 //!     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>;
 //! }
 //! ```
 //!
-//! Unlike `Iterator`, `Stream` makes a distinction between the [`poll_next`]
-//! method which is used when implementing a `Stream`, and a (to-be-implemented)
-//! `next` method which is used when consuming a stream. Consumers of `Stream`
+//! Unlike `Iterator`, `AsyncIterator` makes a distinction between the [`poll_next`]
+//! method which is used when implementing an `AsyncIterator`, and a (to-be-implemented)
+//! `next` method which is used when consuming an async iterator. Consumers of `AsyncIterator`
 //! only need to consider `next`, which when called, returns a future which
-//! yields `Option<Stream::Item>`.
+//! yields `Option<AsyncIterator::Item>`.
 //!
 //! The future returned by `next` will yield `Some(Item)` as long as there are
 //! elements, and once they've all been exhausted, will yield `None` to indicate
 //! that iteration is finished. If we're waiting on something asynchronous to
-//! resolve, the future will wait until the stream is ready to yield again.
+//! resolve, the future will wait until the async iterator is ready to yield again.
 //!
-//! Individual streams may choose to resume iteration, and so calling `next`
+//! Individual async iterators may choose to resume iteration, and so calling `next`
 //! again may or may not eventually yield `Some(Item)` again at some point.
 //!
-//! [`Stream`]'s full definition includes a number of other methods as well,
+//! [`AsyncIterator`]'s full definition includes a number of other methods as well,
 //! but they are default methods, built on top of [`poll_next`], and so you get
 //! them for free.
 //!
 //! [`Poll`]: super::task::Poll
-//! [`poll_next`]: Stream::poll_next
+//! [`poll_next`]: AsyncIterator::poll_next
 //!
-//! # Implementing Stream
+//! # Implementing Async Iterator
 //!
-//! Creating a stream of your own involves two steps: creating a `struct` to
-//! hold the stream's state, and then implementing [`Stream`] for that
+//! Creating an async iterator of your own involves two steps: creating a `struct` to
+//! hold the async iterator's state, and then implementing [`AsyncIterator`] for that
 //! `struct`.
 //!
-//! Let's make a stream named `Counter` which counts from `1` to `5`:
+//! Let's make an async iterator named `Counter` which counts from `1` to `5`:
 //!
 //! ```no_run
-//! #![feature(async_stream)]
-//! # use core::stream::Stream;
+//! #![feature(async_iterator)]
+//! # use core::async_iter::AsyncIterator;
 //! # use core::task::{Context, Poll};
 //! # use core::pin::Pin;
 //!
 //! // First, the struct:
 //!
-//! /// A stream which counts from one to five
+//! /// An async iterator which counts from one to five
 //! struct Counter {
 //!     count: usize,
 //! }
@@ -90,9 +89,9 @@
 //!     }
 //! }
 //!
-//! // Then, we implement `Stream` for our `Counter`:
+//! // Then, we implement `AsyncIterator` for our `Counter`:
 //!
-//! impl Stream for Counter {
+//! impl AsyncIterator for Counter {
 //!     // we will be counting with usize
 //!     type Item = usize;
 //!
@@ -113,17 +112,17 @@
 //!
 //! # Laziness
 //!
-//! Streams are *lazy*. This means that just creating a stream doesn't _do_ a
-//! whole lot. Nothing really happens until you call `poll_next`. This is
-//! sometimes a source of confusion when creating a stream solely for its side
+//! Async iterators are *lazy*. This means that just creating an async iterator doesn't
+//! _do_ a whole lot. Nothing really happens until you call `poll_next`. This is
+//! sometimes a source of confusion when creating an async iterator solely for its side
 //! effects. The compiler will warn us about this kind of behavior:
 //!
 //! ```text
-//! warning: unused result that must be used: streams do nothing unless polled
+//! warning: unused result that must be used: async iterators do nothing unless polled
 //! ```
 
+mod async_iter;
 mod from_iter;
-mod stream;
 
+pub use async_iter::AsyncIterator;
 pub use from_iter::{from_iter, FromIter};
-pub use stream::Stream;
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index afef129303e..aa1ad9362a9 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -305,6 +305,8 @@ pub mod ops;
 pub mod any;
 pub mod array;
 pub mod ascii;
+#[unstable(feature = "async_iterator", issue = "79024")]
+pub mod async_iter;
 pub mod cell;
 pub mod char;
 pub mod ffi;
@@ -316,8 +318,6 @@ pub mod panic;
 pub mod panicking;
 pub mod pin;
 pub mod result;
-#[unstable(feature = "async_stream", issue = "79024")]
-pub mod stream;
 pub mod sync;
 
 pub mod fmt;
diff --git a/library/core/src/panic/unwind_safe.rs b/library/core/src/panic/unwind_safe.rs
index 092b7cf0f2c..95be879e319 100644
--- a/library/core/src/panic/unwind_safe.rs
+++ b/library/core/src/panic/unwind_safe.rs
@@ -1,10 +1,10 @@
+use crate::async_iter::AsyncIterator;
 use crate::cell::UnsafeCell;
 use crate::fmt;
 use crate::future::Future;
 use crate::ops::{Deref, DerefMut};
 use crate::pin::Pin;
 use crate::ptr::{NonNull, Unique};
-use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
 /// A marker trait which represents "panic safe" types in Rust.
@@ -290,8 +290,8 @@ impl<F: Future> Future for AssertUnwindSafe<F> {
     }
 }
 
-#[unstable(feature = "async_stream", issue = "79024")]
-impl<S: Stream> Stream for AssertUnwindSafe<S> {
+#[unstable(feature = "async_iterator", issue = "79024")]
+impl<S: AsyncIterator> AsyncIterator for AssertUnwindSafe<S> {
     type Item = S::Item;
 
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<S::Item>> {
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index a03da0682a5..8c38db9b62c 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -233,7 +233,7 @@
 #![feature(array_error_internals)]
 #![feature(assert_matches)]
 #![feature(associated_type_bounds)]
-#![feature(async_stream)]
+#![feature(async_iterator)]
 #![feature(atomic_mut_ptr)]
 #![feature(auto_traits)]
 #![feature(bench_black_box)]
@@ -404,6 +404,8 @@ pub use alloc_crate::vec;
 pub use core::any;
 #[stable(feature = "core_array", since = "1.36.0")]
 pub use core::array;
+#[unstable(feature = "async_iterator", issue = "79024")]
+pub use core::async_iter;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::cell;
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -458,8 +460,6 @@ pub use core::pin;
 pub use core::ptr;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::result;
-#[unstable(feature = "async_stream", issue = "79024")]
-pub use core::stream;
 #[stable(feature = "i128", since = "1.26.0")]
 #[allow(deprecated, deprecated_in_future)]
 pub use core::u128;