note: external requirements
  --> $DIR/propagate-approximated-ref.rs:43:47
   |
LL |       establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| {
   |  _______________________________________________^
LL | |         // Only works if 'x: 'y:
LL | |         demand_y(x, y, x.get())
LL | |
LL | |     });
   | |_____^
   |
   = note: defining type: supply::{closure#0} with closure substs [
               i16,
               for<'r, 's, 't0, 't1, 't2, 't3> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed('r) }) std::cell::Cell<&'_#1r &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrNamed('s) }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrNamed('t0) }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrNamed('t1) }) &'_#2r u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrNamed('t2) }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrNamed('s) }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 5, kind: BrNamed('t3) }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrNamed('t1) }) u32>)),
               (),
           ]
   = note: late-bound region is '_#3r
   = note: late-bound region is '_#4r
   = note: number of external vids: 5
   = note: where '_#1r: '_#2r

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>) {
LL | |     establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| {
LL | |         // Only works if 'x: 'y:
LL | |         demand_y(x, y, x.get())
LL | |
LL | |     });
LL | | }
   | |_^
   |
   = 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 previous error