| // Similarly to escape-argument-callee, a test case where the closure |
| // requires a relationship between 2 unrelated higher-ranked regions, |
| // with no helpful relations between the HRRs and free regions. |
| // |
| // In this case, the error is reported by the closure itself. This is |
| // because it is unable to approximate the higher-ranked region `'x`, |
| // as it only knows of regions that `'x` is outlived by, and none that |
| // `'x` outlives. |
| |
| // compile-flags:-Zverbose-internals |
| |
| #![feature(rustc_attrs)] |
| |
| use std::cell::Cell; |
| |
| // Callee knows that: |
| // |
| // 'a: 'x |
| // 'b: 'y |
| // |
| // but this doesn't really help us in proving that `'x: 'y`, so |
| // closure gets an error. In particular, we would need to know that |
| // `'x: 'a`, so that we could approximate `'x` "downwards" to `'a`. |
| fn establish_relationships<'a, 'b, F>(_cell_a: &Cell<&'a u32>, _cell_b: &Cell<&'b u32>, _closure: F) |
| where |
| F: for<'x, 'y> FnMut( |
| &Cell<&'x &'a u32>, // shows that 'a: 'x |
| &Cell<&'y &'b u32>, // shows that 'b: 'y |
| &Cell<&'x u32>, |
| &Cell<&'y u32>, |
| ), |
| { |
| } |
| |
| fn demand_y<'x, 'y>(_cell_x: &Cell<&'x u32>, _cell_y: &Cell<&'y u32>, _y: &'y u32) {} |
| |
| #[rustc_regions] |
| fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) { |
| establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| { |
| // Only works if 'x: 'y: |
| demand_y(x, y, x.get()) |
| //~^ ERROR |
| }); |
| } |
| |
| fn main() {} |
