error[E0658]: use of unstable library feature `fn_traits`
  --> $DIR/feature-gate-unboxed-closures-method-calls.rs:4:7
   |
LL |     f.call(());
   |       ^^^^
   |
   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: use of unstable library feature `fn_traits`
  --> $DIR/feature-gate-unboxed-closures-method-calls.rs:5:7
   |
LL |     f.call_mut(());
   |       ^^^^^^^^
   |
   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: use of unstable library feature `fn_traits`
  --> $DIR/feature-gate-unboxed-closures-method-calls.rs:6:7
   |
LL |     f.call_once(());
   |       ^^^^^^^^^
   |
   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0658`.