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
|
// Test that we can derive lifetime bounds on type parameters
// from trait inheritance.
trait Static : 'static { }
trait Is<'a> : 'a { }
struct Inv<'a> {
x: Option<&'a mut &'a isize>
}
fn check_bound<'a,A:'a>(x: Inv<'a>, a: A) { }
// In all of these cases, we can derive a bound for A that is longer
// than 'a based on the trait bound of A:
fn foo1<'a,A:Static>(x: Inv<'a>, a: A) {
check_bound(x, a)
}
fn foo2<'a,A:Static>(x: Inv<'static>, a: A) {
check_bound(x, a)
}
fn foo3<'a,A:Is<'a>>(x: Inv<'a>, a: A) {
check_bound(x, a)
}
// In these cases, there is no trait bound, so we cannot derive any
// bound for A and we get an error:
fn bar1<'a,A>(x: Inv<'a>, a: A) {
check_bound(x, a) //~ ERROR parameter type `A` may not live long enough
}
fn bar2<'a,'b,A:Is<'b>>(x: Inv<'a>, y: Inv<'b>, a: A) {
check_bound(x, a) //~ ERROR parameter type `A` may not live long enough
}
fn main() { }
|
