baz.rs

use core::unstable::intrinsics;
struct S;
impl Drop for S { 
    fn finalize(&self) {}
}       

fn discard(_s: S) {}

fn main() {
    unsafe {
        let p = libc::malloc(sys::size_of::<S>() as libc::size_t) as *mut S; 
        intrinsics::move_val_init(&mut *p, S);
        // ... use p...
        discard(*p);
        libc::free(p as *libc::c_void);
    }           
}           

rustc output

baz.rs:15:19: 15:20 error: use of partially moved value: `p`
baz.rs:15         libc::free(p as *libc::c_void);
                             ^
baz.rs:14:16: 14:18 note: subcomponent of `p` moved here because the subcomponent has type S, which is moved by default (use `copy` to override)
baz.rs:14         discard(*p);
                          ^~
error: aborting due to previous error