7 files changed, 23 insertions, 13 deletions
diff --git a/library/std/src/collections/hash/map.rs b/library/std/src/collections/hash/map.rs
index 829fc3817af..28a25572dd8 100644
--- a/library/std/src/collections/hash/map.rs
+++ b/library/std/src/collections/hash/map.rs
@@ -658,8 +658,7 @@ where
     /// down no lower than the supplied limit while maintaining the internal rules
     /// and possibly leaving some space in accordance with the resize policy.
     ///
-    /// Panics if the current capacity is smaller than the supplied
-    /// minimum capacity.
+    /// If the current capacity is less than the lower limit, this is a no-op.
     ///
     /// # Examples
     ///
@@ -679,7 +678,6 @@ where
     #[inline]
     #[unstable(feature = "shrink_to", reason = "new API", issue = "56431")]
     pub fn shrink_to(&mut self, min_capacity: usize) {
-        assert!(self.capacity() >= min_capacity, "Tried to shrink to a larger capacity");
         self.base.shrink_to(min_capacity);
     }
 
diff --git a/library/std/src/collections/hash/set.rs b/library/std/src/collections/hash/set.rs
index baa3026ff75..b08510d6b01 100644
--- a/library/std/src/collections/hash/set.rs
+++ b/library/std/src/collections/hash/set.rs
@@ -462,9 +462,7 @@ where
     /// down no lower than the supplied limit while maintaining the internal rules
     /// and possibly leaving some space in accordance with the resize policy.
     ///
-    /// Panics if the current capacity is smaller than the supplied
-    /// minimum capacity.
-    ///
+    /// If the current capacity is less than the lower limit, this is a no-op.
     /// # Examples
     ///
     /// ```
diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index 32f0f8a52f8..21060182d60 100644
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -304,8 +304,7 @@ impl OsString {
     /// The capacity will remain at least as large as both the length
     /// and the supplied value.
     ///
-    /// Panics if the current capacity is smaller than the supplied
-    /// minimum capacity.
+    /// If the current capacity is less than the lower limit, this is a no-op.
     ///
     /// # Examples
     ///
diff --git a/library/std/src/io/buffered/bufreader.rs b/library/std/src/io/buffered/bufreader.rs
index 8bae3da1273..987371f50ec 100644
--- a/library/std/src/io/buffered/bufreader.rs
+++ b/library/std/src/io/buffered/bufreader.rs
@@ -410,7 +410,6 @@ impl<R: Seek> Seek for BufReader<R> {
     /// # Example
     ///
     /// ```no_run
-    /// #![feature(seek_convenience)]
     /// use std::{
     ///     io::{self, BufRead, BufReader, Seek},
     ///     fs::File,
diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs
index c87a56586c6..db3b0e2628f 100644
--- a/library/std/src/io/mod.rs
+++ b/library/std/src/io/mod.rs
@@ -1671,7 +1671,7 @@ pub trait Seek {
     /// # Example
     ///
     /// ```no_run
-    /// #![feature(seek_convenience)]
+    /// #![feature(seek_stream_len)]
     /// use std::{
     ///     io::{self, Seek},
     ///     fs::File,
@@ -1685,7 +1685,7 @@ pub trait Seek {
     ///     Ok(())
     /// }
     /// ```
-    #[unstable(feature = "seek_convenience", issue = "59359")]
+    #[unstable(feature = "seek_stream_len", issue = "59359")]
     fn stream_len(&mut self) -> Result<u64> {
         let old_pos = self.stream_position()?;
         let len = self.seek(SeekFrom::End(0))?;
@@ -1706,7 +1706,6 @@ pub trait Seek {
     /// # Example
     ///
     /// ```no_run
-    /// #![feature(seek_convenience)]
     /// use std::{
     ///     io::{self, BufRead, BufReader, Seek},
     ///     fs::File,
@@ -1723,7 +1722,7 @@ pub trait Seek {
     ///     Ok(())
     /// }
     /// ```
-    #[unstable(feature = "seek_convenience", issue = "59359")]
+    #[stable(feature = "seek_convenience", since = "1.51.0")]
     fn stream_position(&mut self) -> Result<u64> {
         self.seek(SeekFrom::Current(0))
     }
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 933e9229fdb..c1b79ff716c 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -224,6 +224,7 @@
 #![feature(allocator_internals)]
 #![feature(allow_internal_unsafe)]
 #![feature(allow_internal_unstable)]
+#![feature(async_stream)]
 #![feature(arbitrary_self_types)]
 #![feature(array_error_internals)]
 #![feature(asm)]
@@ -449,6 +450,8 @@ pub use core::ptr;
 pub use core::raw;
 #[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;
diff --git a/library/std/src/panic.rs b/library/std/src/panic.rs
index 0f568da459b..c4118bf5d9e 100644
--- a/library/std/src/panic.rs
+++ b/library/std/src/panic.rs
@@ -12,6 +12,7 @@ use crate::panicking;
 use crate::pin::Pin;
 use crate::ptr::{NonNull, Unique};
 use crate::rc::Rc;
+use crate::stream::Stream;
 use crate::sync::atomic;
 use crate::sync::{Arc, Mutex, RwLock};
 use crate::task::{Context, Poll};
@@ -340,6 +341,19 @@ impl<F: Future> Future for AssertUnwindSafe<F> {
     }
 }
 
+#[unstable(feature = "async_stream", issue = "79024")]
+impl<S: Stream> Stream for AssertUnwindSafe<S> {
+    type Item = S::Item;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<S::Item>> {
+        unsafe { self.map_unchecked_mut(|x| &mut x.0) }.poll_next(cx)
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
+}
+
 /// Invokes a closure, capturing the cause of an unwinding panic if one occurs.
 ///
 /// This function will return `Ok` with the closure's result if the closure