error[E0658]: rust-call ABI is subject to change --> $DIR/feature-gate-unboxed-closures.rs:9:12 | LL | extern "rust-call" fn call_once(self, (a, b): (u32, u32)) -> u32 { | ^^^^^^^^^^^ | = note: for more information, see https://github.com/rust-lang/rust/issues/29625 = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable error[E0658]: the precise format of `Fn`-family traits' type parameters is subject to change. Use parenthetical notation (Fn(Foo, Bar) -> Baz) instead --> $DIR/feature-gate-unboxed-closures.rs:5:6 | LL | impl FnOnce<(u32, u32)> for Test { | ^^^^^^^^^^^^^^^^^^ | = note: for more information, see https://github.com/rust-lang/rust/issues/29625 = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0658`.