type lexHeap []loader.Sym

func (h *lexHeap) push(ldr *loader.Loader, s loader.Sym) {
	*h = append(*h, s)
	// sift up
	n := len(*h) - 1
	for n > 0 {
		p := (n - 1) / 2 // parent
		if ldr.SymName((*h)[p]) <= ldr.SymName((*h)[n]) {
			break
		}
		(*h)[n], (*h)[p] = (*h)[p], (*h)[n]
		n = p
	}
}

func (h *lexHeap) pop(ldr *loader.Loader) loader.Sym {
	r := (*h)[0]

	}
	var edges []edge

	// List of packages that are ready to schedule. We use a lexicographic
	// ordered heap to pick the lexically earliest uninitialized but
	// inititalizeable package at each step.
	var h lexHeap

	// m maps from an inittask symbol for package p to the number of
	// p's direct imports that have not yet been scheduled.
	m := map[loader.Sym]int{}

	// Find all reachable inittask records from the roots.