issue w/ borrows within a loop

build spew

jeff@mbp:~/src/dungeongame (master)$ make
check: formatting
make -C p2d -f Makefile
check: formatting
rustc  -L lib --opt-level=3 --out-dir lib -D warnings --dep-info .rust/p2dux.deps.mk src/p2dux/lib.rs
src/p2dux/view/mod.rs:61:29: 61:37 error: cannot borrow `*passives` as mutable more than once at a time
src/p2dux/view/mod.rs:61                 for view in passives.mut_iter() {
                                                     ^~~~~~~~
src/p2dux/view/mod.rs:71:67: 71:75 note: previous borrow of `*passives` occurs here; the mutable borrow prevents subsequent moves, borrows, or modification of
 `*passives` until the borrow ends
src/p2dux/view/mod.rs:71             match active.handle(display, events.as_slice(), time, passives, self) {
                                                                                           ^~~~~~~~
src/p2dux/view/mod.rs:77:6: 77:6 note: previous borrow ends here
src/p2dux/view/mod.rs:54                            passives: &'a mut Vec<&'a mut PassiveView>) -> TOut {
...
src/p2dux/view/mod.rs:77     }
                             ^
src/p2dux/view/mod.rs:71:19: 71:25 error: cannot borrow `*active` as mutable more than once at a time
src/p2dux/view/mod.rs:71             match active.handle(display, events.as_slice(), time, passives, self) {
                                           ^~~~~~
src/p2dux/view/mod.rs:71:19: 71:25 note: previous borrow of `*active` occurs here; the mutable borrow prevents subsequent moves, borrows, or modification of $
*active` until the borrow ends
src/p2dux/view/mod.rs:71             match active.handle(display, events.as_slice(), time, passives, self) {
                                           ^~~~~~
src/p2dux/view/mod.rs:77:6: 77:6 note: previous borrow ends here
src/p2dux/view/mod.rs:54                            passives: &'a mut Vec<&'a mut PassiveView>) -> TOut {
...
src/p2dux/view/mod.rs:77     }
                             ^
src/p2dux/view/mod.rs:71:67: 71:75 error: cannot borrow `*passives` as mutable more than once at a time
src/p2dux/view/mod.rs:71             match active.handle(display, events.as_slice(), time, passives, self) {
                                                                                           ^~~~~~~~
src/p2dux/view/mod.rs:71:67: 71:75 note: previous borrow of `*passives` occurs here; the mutable borrow prevents subsequent moves, borrows, or modification o$
 `*passives` until the borrow ends
src/p2dux/view/mod.rs:71             match active.handle(display, events.as_slice(), time, passives, self) {
                                                                                           ^~~~~~~~
src/p2dux/view/mod.rs:77:6: 77:6 note: previous borrow ends here
src/p2dux/view/mod.rs:54                            passives: &'a mut Vec<&'a mut PassiveView>) -> TOut {
...
src/p2dux/view/mod.rs:77     }
                             ^
src/p2dux/view/mod.rs:71:77: 71:81 error: cannot borrow `*self` as mutable more than once at a time
src/p2dux/view/mod.rs:71             match active.handle(display, events.as_slice(), time, passives, self) {
                                                                                                     ^~~~
src/p2dux/view/mod.rs:71:77: 71:81 note: previous borrow of `*self` occurs here; the mutable borrow prevents subsequent moves, borrows, or modification of `*$
elf` until the borrow ends
src/p2dux/view/mod.rs:71             match active.handle(display, events.as_slice(), time, passives, self) {
                                                                                                     ^~~~
src/p2dux/view/mod.rs:77:6: 77:6 note: previous borrow ends here
src/p2dux/view/mod.rs:54                            passives: &'a mut Vec<&'a mut PassiveView>) -> TOut {
...
src/p2dux/view/mod.rs:77     }
                             ^
error: aborting due to 4 previous errors

fails.rs

impl ViewManager {
    pub fn enter_once<'a, TOut: Send>(&'a mut self, display: &GameDisplay,
                           yielding: &'a mut PassiveView,
                           active: &'a mut ActiveView<TOut>,
                           passives: &'a mut Vec<&'a mut PassiveView>) -> Option<TOut> {
        passives.push(yielding);
        let (sender, receiver) = channel();
        loop {
            let time = 0;
            let mut events = Vec::new();
            {
                for view in passives.mut_iter() {
                    view.update(display, time);
                }
            }
            loop {
                match poll_event() {
                    NoEvent => { break; },
                    event => { events.push(event); }
                }
            }
            match active.handle(display, events.as_slice(), time, passives, self) {
                Some(out) => { sender.send(out); break },
                _ => {}
            }
        }
        receiver.recv()
    }
}

vm.rs

// this builds

pub trait ActiveView<TOut> : PassiveView {
    fn handle<'a> (&'a mut self, display: &GameDisplay, events: &[Event], time: u64,
              passives: &'a mut Vec<&'a mut PassiveView>, yielder: &'a mut ViewManager)
        -> Option<TOut>;
}
pub trait PassiveView {
    fn update(&mut self, display: &GameDisplay, time: u64);
}

pub struct ViewManager;

impl ViewManager {
    pub fn enter_once<'a, TOut: Send>(&'a mut self, display: &GameDisplay,
                           yielding: &'a mut PassiveView,
                           active: &'a mut ActiveView<TOut>,
                           passives: &'a mut Vec<&'a mut PassiveView>) -> Option<TOut> {
        passives.push(yielding);
        let time = 0;
        let mut events = Vec::new();
        {
            for view in passives.mut_iter() {
                view.update(display, time);
            }
        }
        loop {
            match poll_event() {
                NoEvent => { break; },
                event => { events.push(event); }
            }
        }
        active.handle(display, events.as_slice(), time, passives, self)
    }
}