Add docs + To unstable feature

src/stream/stream/flatten.rs

@@ -5,6 +5,11 @@ use crate::stream::stream::map::Map;
 use crate::stream::{IntoStream, Stream};
 use crate::task::{Context, Poll};
 
+/// This `struct` is created by the [`flat_map`] method on [`Stream`]. See its
+/// documentation for more.
+///
+/// [`flat_map`]: trait.Stream.html#method.flat_map
+/// [`Stream`]: trait.Stream.html
 #[allow(missing_debug_implementations)]
 pub struct FlatMap<S: Stream, U: IntoStream, F> {
     inner: FlattenCompat<Map<S, F, S::Item, U>, U>,
@@ -39,6 +44,12 @@ where
     }
 }
 
+/// This `struct` is created by the [`flatten`] method on [`Stream`]. See its
+/// documentation for more.
+///
+/// [`flatten`]: trait.Stream.html#method.flatten
+/// [`Stream`]: trait.Stream.html
+#[allow(missing_debug_implementations)]
 pub struct Flatten<S: Stream>
 where
     S::Item: IntoStream,

src/stream/stream/mod.rs

@@ -30,7 +30,6 @@ mod filter;
 mod filter_map;
 mod find;
 mod find_map;
-mod flatten;
 mod fold;
 mod for_each;
 mod fuse;
@@ -78,7 +77,6 @@ use try_for_each::TryForEeachFuture;
 
 pub use chain::Chain;
 pub use filter::Filter;
-pub use flatten::{FlatMap, Flatten};
 pub use fuse::Fuse;
 pub use inspect::Inspect;
 pub use map::Map;
@@ -93,17 +91,18 @@ pub use zip::Zip;
 use std::cmp::Ordering;
 use std::marker::PhantomData;
 
-use crate::stream::IntoStream;
-
 cfg_unstable! {
     use std::pin::Pin;
 
     use crate::future::Future;
     use crate::stream::FromStream;
+    use crate::stream::into_stream::IntoStream;
 
     pub use merge::Merge;
+    pub use flatten::{FlatMap, Flatten};
 
     mod merge;
+    mod flatten;
 }
 
 extension_trait! {
@@ -589,6 +588,8 @@ extension_trait! {
             # });
             ```
         "#]
+        #[cfg(feature = "unstable")]
+        #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
         fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>
             where
                 Self: Sized,
@@ -621,6 +622,8 @@ extension_trait! {
 
             # });
         "#]
+        #[cfg(feature = "unstable")]
+        #[cfg_attr(feature = "docs", doc(cfg(unstable)))]
         fn flatten(self) -> Flatten<Self>
         where
             Self: Sized,