Compiling futuretest v0.1.0 (file:///mnt/c/Users/Mahmoud/git/futuretest)
error[E0277]: the trait bound `(): futures::Future` is not satisfied
  --> src/main.rs:17:1
   |
17 | / fn test() -> MapErr<(), ()> {
18 | |     future::ok(())
19 | |         .map_err(|String| ())
20 | | }
   | |_^ the trait `futures::Future` is not implemented for `()`
   |
   = note: required by `futures::MapErr`

error: aborting due to previous error

error: Could not compile `futuretest`.

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