Confusing error message when wildcard importing two same-named traits

[mehcode]

Discovered this when using tokio-async-await and futures. Both define FutureExt and StreamExt traits in their preludes. Both traits are meant to be used at the same time (from what I understand).

use tokio::prelude::*;  // contains StreamExt, FutureExt
use futures::prelude::*;  // contains StreamExt, FutureExt

After doing both this imports rust proceeds to act like neither of the traits got imported and give error help on any method usage something like "trait not in scope; use tokio::async_await::stream::StreamExt".

Here is a Rust playground illustrating the bug: https://play.rust-lang.org/?gist=c8ebd2f79eca354ecb2dd6c828d73ad0&version=nightly&mode=debug&edition=2015

And here is a work-around for it (in nightly): https://play.rust-lang.org/?gist=f28928ef69a1985ee79d321cb58ae7e1&version=nightly&mode=debug&edition=2015

I think the way forward here is a good warning (or error) message when a duplicate trait item import happens between two wildcard imports.