error[E0308]: mismatched types --> $DIR/len.rs:3:10 | LL | test(array.len()); | ---- ^^^^^^^^^^^ expected `u32`, found `usize` | | | arguments to this function are incorrect | note: function defined here --> $DIR/len.rs:6:4 | LL | fn test(length: u32) { | ^^^^ ----------- help: you can convert a `usize` to a `u32` and panic if the converted value doesn't fit | LL | test(array.len().try_into().unwrap()); | ++++++++++++++++++++ error: aborting due to previous error For more information about this error, try `rustc --explain E0308`.