1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
// A simpler variant of `outlives-from-argument` where cells are
// passed by value.
//
// This is simpler because there are no "extraneous" region
// relationships. In the 'main' variant, there are a number of
// anonymous regions as well.
// compile-flags:-Zverbose
#![feature(rustc_attrs)]
use std::cell::Cell;
// Callee knows that:
//
// 'x: 'a
// 'b: 'y
//
// so if we are going to ensure that `'x: 'y`, then `'a: 'b` must
// hold.
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<&'a &'x u32>, // shows that 'x: 'a
Cell<&'y &'b u32>, // shows that 'b: 'y
Cell<&'x u32>,
Cell<&'y u32>,
),
{
}
fn demand_y<'x, 'y>(_outlives1: Cell<&&'x u32>, _outlives2: Cell<&'y &u32>, _y: &'y u32) {}
#[rustc_regions]
fn test<'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(outlives1, outlives2, x.get())
//~^ ERROR lifetime may not live long enough
});
}
fn main() {}
|
