1error[E0658]: parenthetical notation is only stable when used with `Fn`-family traits
2  --> $DIR/unboxed-closure-feature-gate.rs:13:20
3   |
4LL |     let x: Box<dyn Foo(isize)>;
5   |                    ^^^^^^^^^^
6   |
7   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
8   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
9
10error: aborting due to previous error
11
12For more information about this error, try `rustc --explain E0658`.
13