Macro claim::assert_none

macro_rules! assert_none {
    ($cond:expr) => { ... };
    ($cond:expr,) => { ... };
    ($cond:expr, $($arg:tt)+) => { ... };
}

Asserts that expression returns None variant.

Examples

let maybe: Option<i32> = None;

assert_none!(maybe);

let maybe = Some(42i32);

assert_none!(maybe);  // Will panic