error[E0277]: the size for values of type `[i32]` cannot be known at compilation time
  --> $DIR/issue-30276.rs:4:29
   |
LL |     let _x: fn(_) -> Test = Test;
   |                             ^^^^ doesn't have a size known at compile-time
   |
   = help: the trait `Sized` is not implemented for `[i32]`
   = note: all function arguments must have a statically known size
   = help: unsized fn params are gated as an unstable feature

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0277`.