This commit deprecates the `sync::Future` type to be developed outside in
crates.io instead.
reason = "futures as-is have yet to be deeply reevaluated with recent \
core changes to Rust's synchronization story, and will likely \
become stable in the future but are unstable until that time")]
+#[deprecated(since = "1.2.0",
+ reason = "implementation does not match the quality of the \
+ standard library and this will likely be prototyped \
+ outside in crates.io first")]
use core::prelude::*;
use core::mem::replace;