Error code E0600

An unary operator was used on a type which doesn’t implement it.

Erroneous code example:

enum Question {
    Yes,
    No,
}

!Question::Yes; // error: cannot apply unary operator `!` to type `Question`

Run

In this case, Question would need to implement the std::ops::Not trait in order to be able to use ! on it. Let’s implement it:

use std::ops::Not;

enum Question {
    Yes,
    No,
}

// We implement the `Not` trait on the enum.
impl Not for Question {
    type Output = bool;

    fn not(self) -> bool {
        match self {
            Question::Yes => false, // If the `Answer` is `Yes`, then it
                                    // returns false.
            Question::No => true, // And here we do the opposite.
        }
    }
}

assert_eq!(!Question::Yes, false);
assert_eq!(!Question::No, true);

Run

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