#[warn(collapsible_if)]
fn main() {
    let x = "hello";
    let y = "world";
    if x == "hello" {
        if y == "world" {
            println!("Hello world!");
        }
    }

    if x == "hello" || x == "world" {
        if y == "world" || y == "hello" {
            println!("Hello world!");
        }
    }

    if x == "hello" && x == "world" {
        if y == "world" || y == "hello" {
            println!("Hello world!");
        }
    }

    if x == "hello" || x == "world" {
        if y == "world" && y == "hello" {
            println!("Hello world!");
        }
    }

    if x == "hello" && x == "world" {
        if y == "world" && y == "hello" {
            println!("Hello world!");
        }
    }

    if 42 == 1337 {
        if 'a' != 'A' {
            println!("world!")
        }
    }

    // Collaspe `else { if .. }` to `else if ..`
    if x == "hello" {
        print!("Hello ");
    } else {
        if y == "world" {
            println!("world!")
        }
    }

    if x == "hello" {
        print!("Hello ");
    } else {
        if let Some(42) = Some(42) {
            println!("world!")
        }
    }

    if x == "hello" {
        print!("Hello ");
    } else {
        if y == "world" {
            println!("world")
        }
        else {
            println!("!")
        }
    }

    if x == "hello" {
        print!("Hello ");
    } else {
        if let Some(42) = Some(42) {
            println!("world")
        }
        else {
            println!("!")
        }
    }

    if let Some(42) = Some(42) {
        print!("Hello ");
    } else {
        if let Some(42) = Some(42) {
            println!("world")
        }
        else {
            println!("!")
        }
    }

    if let Some(42) = Some(42) {
        print!("Hello ");
    } else {
        if x == "hello" {
            println!("world")
        }
        else {
            println!("!")
        }
    }

    if let Some(42) = Some(42) {
        print!("Hello ");
    } else {
        if let Some(42) = Some(42) {
            println!("world")
        }
        else {
            println!("!")
        }
    }

    // Works because any if with an else statement cannot be collapsed.
    if x == "hello" {
        if y == "world" {
            println!("Hello world!");
        }
    } else {
        println!("Not Hello world");
    }

    if x == "hello" {
        if y == "world" {
            println!("Hello world!");
        } else {
            println!("Hello something else");
        }
    }

    if x == "hello" {
        print!("Hello ");
        if y == "world" {
            println!("world!")
        }
    }

    if true {
    } else {
        assert!(true); // assert! is just an `if`
    }
}