async-trait, issue #75

Cargo.toml

[package]
name = "async-trait-75"
version = "0.1.0"
authors = []
edition = "2018"

[dependencies]
async-trait = "0.1.17"
tokio = { version = "0.2.13", features = [ "rt-threaded", "macros" ] }

output.txt

$ cargo build
   Compiling async-trait-75 v0.1.0 (/Users/user/async-trait-test)
warning: unused implementer of `std::future::Future` that must be used
  --> src/main.rs:26:5
   |
26 |     thing.do_direct();
   |     ^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_must_use)]` on by default
   = note: futures do nothing unless you `.await` or poll them

    Finished dev [unoptimized + debuginfo] target(s) in 1.35s

src_main.rs

#[async_trait::async_trait]
trait Interface {
    async fn do_trait(&self);
}

struct Thing;

#[async_trait::async_trait]
impl Interface for Thing {
    async fn do_trait(&self) {
        println!("hello from trait");
    }
}

impl Thing {
    async fn do_direct(&self) {
        println!("hello from direct");
    }
}

#[tokio::main]
async fn main() {
    let thing = Thing {};

    thing.do_trait();
    thing.do_direct();
}

cf. dtolnay/async-trait#75