Document feature gate for async-await features

Author: Nemo157

futures-util/src/async_await/join.rs

@@ -7,6 +7,8 @@
 /// `join!` polls both futures concurrently and therefore is more efficent.
 ///
 /// This macro is only usable inside of async functions, closures, and blocks.
+/// It is also gated behind the `async-await` feature of this library, which is
+/// _not_ activated by default.
 ///
 /// # Examples
 ///
@@ -53,6 +55,8 @@ macro_rules! join {
 /// the futures return an error.
 ///
 /// This macro is only usable inside of async functions, closures, and blocks.
+/// It is also gated behind the `async-await` feature of this library, which is
+/// _not_ activated by default.
 ///
 /// # Examples
 ///

futures-util/src/async_await/pending.rs

@@ -10,6 +10,8 @@ use futures_core::task::{Context, Poll};
 /// is called somewhere when further progress can be made.
 ///
 /// This macro is only usable inside of async functions, closures, and blocks.
+/// It is also gated behind the `async-await` feature of this library, which is
+/// _not_ activated by default.
 #[macro_export]
 macro_rules! pending {
     () => {

futures-util/src/async_await/poll.rs

@@ -6,6 +6,8 @@ use futures_core::task::{Context, Poll};
 /// current `async` context.
 ///
 /// This macro is only usable inside of `async` functions, closures, and blocks.
+/// It is also gated behind the `async-await` feature of this library, which is
+/// _not_ activated by default.
 #[macro_export]
 macro_rules! poll {
     ($x:expr) => {

futures-util/src/async_await/select_mod.rs

@@ -20,6 +20,8 @@ macro_rules! document_select_macro {
         /// branch has to have the same return type.
         ///
         /// This macro is only usable inside of async functions, closures, and blocks.
+        /// It is also gated behind the `async-await` feature of this library, which is
+        /// _not_ activated by default.
         ///
         /// # Examples
         ///