Code shared from the Rust Playground

playground.rs

#[test]
fn floor_negative() {
    // With parentheses around the number, this works.
    assert_eq!((-1.01f64).floor(), -2.0);

    // Without parentheses, the meaning is "the negation of `1.01f64.floor()`"
    // which gives a different answer.
    assert_eq!(-1.01f64.floor(), -1.0);
}