Unsupported constant string in println about prusti-dev HOT 1 OPEN

The error message is reporting that the string used in the println! is not supported. At the moment, there is not much that we do to veryify I/O or string properties. To work around the error you could mark play_game as #[trusted], meaning that it won't be verified.

If you still want to prove some properties about it you could, for example, add a parameter to counts how many times the play_game function has been executed. This makes it possible to prove properties in the code that calls play_game. However, it depends a lot on what you want to do.

#[trusted]
#[ensures(*counter == old(*counter) + 1)]
pub fn play_game(n: u32, counter: &mut usize) {
    println!("{}", fizz_buzz_fibonacci(n));
    counter += 1;
}

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