error[E0658]: the precise format of `Fn`-family traits' type parameters is subject to change
  --> $DIR/fn-trait-notation.rs:4:8
   |
LL |     F: Fn<i32, Output = i32>,
   |        ^^^^^^^^^^^^^^^^^^^^^ help: use parenthetical notation instead: `Fn(i32) -> i32`
   |
   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
   = 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
  --> $DIR/fn-trait-notation.rs:5:8
   |
LL |     G: Fn<(i32, i32, ), Output = (i32, i32)>,
   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use parenthetical notation instead: `Fn(i32, i32) -> (i32, i32)`
   |
   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
   = 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
  --> $DIR/fn-trait-notation.rs:6:8
   |
LL |     H: Fn<(i32,), Output = i32>,
   |        ^^^^^^^^^^^^^^^^^^^^^^^^ help: use parenthetical notation instead: `Fn(i32) -> i32`
   |
   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable

error: aborting due to 3 previous errors

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