1 error[E0308]: mismatched types
2 --> $DIR/issue-90213-expected-boxfuture-self-ice.rs:9:19
5 | ^^^^ expected struct `Box`, found enum `Option`
7 = note: expected struct `Box<Option<S>>`
9 = 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
10 help: store this in the heap by calling `Box::new`
12 LL | Self::foo(Box::new(None))
15 error: aborting due to previous error
17 For more information about this error, try `rustc --explain E0308`.