note: external requirements
  --> $DIR/propagate-approximated-ref.rs:43:47
   |
LL |     establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| {
   |                                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: defining type: supply::{closure#0} with closure args [
               i16,
               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) &'?2 u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 5, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>)),
               (),
           ]
   = note: late-bound region is '?3
   = note: late-bound region is '?4
   = note: number of external vids: 5
   = note: where '?1: '?2

note: no external requirements
  --> $DIR/propagate-approximated-ref.rs:42:1
   |
LL | fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: defining type: supply

error: lifetime may not live long enough
  --> $DIR/propagate-approximated-ref.rs:45:9
   |
LL | fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) {
   |           --  -- lifetime `'b` defined here
   |           |
   |           lifetime `'a` defined here
...
LL |         demand_y(x, y, x.get())
   |         ^^^^^^^^^^^^^^^^^^^^^^^ argument requires that `'a` must outlive `'b`
   |
   = help: consider adding the following bound: `'a: 'b`

error: aborting due to 1 previous error