Struct DequePayload 

#[repr(C)]
pub struct DequePayload {
    pub element_descriptor: *const TypeDescriptor,
    pub items: VecDeque<GcRef>,
}

The Deque[T] payload: the element descriptor plus a growable VecDeque. VecDeque (not Vec) so push_front/pop_front are O(1) amortized. Both fields are Drop, so DEQUE’s drop_value releases them on sweep.

Fields

element_descriptor: *const TypeDescriptor

The descriptor for every element, or null for “not told yet” — VecPayload::element_descriptor’s contract exactly. Read it through [ElementSeq::element].

items: VecDeque<GcRef>

The elements. A VecDeque so both ends are cheap to mutate.