Error code E0054

It is not allowed to cast to a bool.

Erroneous code example:

#![allow(unused)] fn main() { let x = 5; // Not allowed, won't compile let x_is_nonzero = x as bool; }

If you are trying to cast a numeric type to a bool, you can compare it with zero instead:

#![allow(unused)] fn main() { let x = 5; // Ok let x_is_nonzero = x != 0; }