error: expected type, found `"foo"`
  --> $DIR/type-ascription-instead-of-method.rs:3:21
   |
LL |     let _ = Box:new("foo".to_string());
   |                -    ^^^^^ expected type
   |                |
   |                help: maybe write a path separator here: `::`
   |
   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`

error: aborting due to previous error