Upgrade rust/crates/futures-executor to 0.3.12
Test: make
Change-Id: I12d01f1fee572bd237ca5f26f369e7ae2e65ddc6
diff --git a/src/lib.rs b/src/lib.rs
index a8ba5c8..b679649 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,40 @@
//! Built-in executors and related tools.
//!
-//! All items of this library are only available when the `std` feature of this
+//! All asynchronous computation occurs within an executor, which is
+//! capable of spawning futures as tasks. This module provides several
+//! built-in executors, as well as tools for building your own.
+//!
+//! All items are only available when the `std` feature of this
//! library is activated, and it is activated by default.
+//!
+//! # Using a thread pool (M:N task scheduling)
+//!
+//! Most of the time tasks should be executed on a [thread pool](ThreadPool).
+//! A small set of worker threads can handle a very large set of spawned tasks
+//! (which are much lighter weight than threads). Tasks spawned onto the pool
+//! with the [`spawn_ok`](ThreadPool::spawn_ok) function will run ambiently on
+//! the created threads.
+//!
+//! # Spawning additional tasks
+//!
+//! Tasks can be spawned onto a spawner by calling its [`spawn_obj`] method
+//! directly. In the case of `!Send` futures, [`spawn_local_obj`] can be used
+//! instead.
+//!
+//! # Single-threaded execution
+//!
+//! In addition to thread pools, it's possible to run a task (and the tasks
+//! it spawns) entirely within a single thread via the [`LocalPool`] executor.
+//! Aside from cutting down on synchronization costs, this executor also makes
+//! it possible to spawn non-`Send` tasks, via [`spawn_local_obj`]. The
+//! [`LocalPool`] is best suited for running I/O-bound tasks that do relatively
+//! little work between I/O operations.
+//!
+//! There is also a convenience function [`block_on`] for simply running a
+//! future to completion on the current thread.
+//!
+//! [`spawn_obj`]: https://docs.rs/futures/0.3/futures/task/trait.Spawn.html#tymethod.spawn_obj
+//! [`spawn_local_obj`]: https://docs.rs/futures/0.3/futures/task/trait.LocalSpawn.html#tymethod.spawn_local_obj
#![cfg_attr(not(feature = "std"), no_std)]
@@ -9,16 +42,8 @@
// It cannot be included in the published code because this lints have false positives in the minimum required version.
#![cfg_attr(test, warn(single_use_lifetimes))]
#![warn(clippy::all)]
-
-// mem::take requires Rust 1.40, matches! requires Rust 1.42
-// Can be removed if the minimum supported version increased or if https://github.com/rust-lang/rust-clippy/issues/3941
-// get's implemented.
-#![allow(clippy::mem_replace_with_default, clippy::match_like_matches_macro)]
-
#![doc(test(attr(deny(warnings), allow(dead_code, unused_assignments, unused_variables))))]
-#![doc(html_root_url = "https://docs.rs/futures-executor/0.3.7")]
-
#![cfg_attr(docsrs, feature(doc_cfg))]
#[cfg(feature = "std")]
