error: expected type, found `<[_]>::into_vec(#[rustc_box] ::alloc::boxed::Box::new([0, 1]))` --> $DIR/issue-47666.rs:3:25 | LL | let _ = Option:Some(vec![0, 1]); | - ^^^^^^^^^^ | | | | | expected type | | in this macro invocation | | this macro call doesn't expand to a type | help: maybe write a path separator here: `::` | = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `: ` = note: this error originates in the macro `$crate::__rust_force_expr` which comes from the expansion of the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info) error: aborting due to previous error