error[E0562]: `impl Trait` not allowed outside of function and inherent method return types
  --> $DIR/issue-58504.rs:10:16
   |
LL |     let gens: [impl Generator<Return=!, Yield=()>;2] = [ mk_gen(), mk_gen() ];
   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: found `impl Trait` in variable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0562`.