error[E0271]: expected `{async closure@dont-suggest-boxing-async-closure-body.rs:9:9}` to return `Box<_>`, but it returns `{async closure body@$DIR/dont-suggest-boxing-async-closure-body.rs:9:23: 9:25}`
found closure `{async closure@$DIR/dont-suggest-boxing-async-closure-body.rs:11:9: 11:22}`
= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html