error[E0658]: the precise format of `Fn`-family traits' type parameters is subject to change --> $DIR/issue-23024.rs:8:39 | LL | println!("{:?}",(vfnfer[0] as dyn Fn)(3)); | ^^ help: use parenthetical notation instead: `Fn() -> ()` | = note: see issue #29625 for more information = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable error[E0107]: missing generics for trait `Fn` --> $DIR/issue-23024.rs:8:39 | LL | println!("{:?}",(vfnfer[0] as dyn Fn)(3)); | ^^ expected 1 generic argument | help: add missing generic argument | LL | println!("{:?}",(vfnfer[0] as dyn Fn)(3)); | ++++++ error[E0191]: the value of the associated type `Output` (from trait `FnOnce`) must be specified --> $DIR/issue-23024.rs:8:39 | LL | println!("{:?}",(vfnfer[0] as dyn Fn)(3)); | ^^ help: specify the associated type: `Fn` error: aborting due to 3 previous errors Some errors have detailed explanations: E0107, E0191, E0658. For more information about an error, try `rustc --explain E0107`.