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`.