example showing when rustc encourages uninitalized variable.

gistfile1.txt

// CODE:
static s : int = 3;
static t : *int = &s as *int;

fn main() {
    let mut x = 3;
    unsafe {
        x = *t;
    }
    io::println(fmt!("Hello World %d", x));
}

/* RUSTC:
% rustc /tmp/bug8.rs
/tmp/bug8.rs:5:12: 5:15 warning: value assigned to `x` is never read
/tmp/bug8.rs:5     let mut x = 3;
                           ^~~
warning: no debug symbols in executable (-arch x86_64)
*/