Never type - The Rust Reference

# Never type

> Syntax
> NeverType : `!`

The never type `!` is a type with no values, representing the result of computations that never complete. Expressions of type `!` can be coerced into any other type.

    let x: ! = panic!();
    // Can be coerced into any type.
    let y: u32 = x;

NB. The never type was expected to be stabilized in 1.41, but due to some last minute regressions detected the stabilization was temporarily reverted. The `!` type can only appear in function return types presently. See the tracking issue for more details.