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
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
// edition:2021
// check-pass
#![allow(unreachable_code)]
#![warn(unused)]
#![allow(dead_code)]
#[derive(Debug)]
struct Point {
x: i32,
y: i32,
}
pub fn f() {
let mut a = 1;
let mut c = Point{ x:1, y:0 };
// Captured by value, but variable is dead on entry.
(move || {
// This will not trigger a warning for unused variable as
// c.x will be treated as a Non-tracked place
c.x = 1;
println!("{}", c.x);
a = 1; //~ WARN value captured by `a` is never read
println!("{}", a);
})();
// Read and written to, but never actually used.
(move || {
// This will not trigger a warning for unused variable as
// c.x will be treated as a Non-tracked place
c.x += 1;
a += 1; //~ WARN unused variable: `a`
})();
(move || {
println!("{}", c.x);
// Value is read by closure itself on later invocations.
// This will not trigger a warning for unused variable as
// c.x will be treated as a Non-tracked place
c.x += 1;
println!("{}", a);
a += 1;
})();
let b = Box::new(42);
(move || {
println!("{}", c.x);
// Never read because this is FnOnce closure.
// This will not trigger a warning for unused variable as
// c.x will be treated as a Non-tracked place
c.x += 1;
println!("{}", a);
a += 1; //~ WARN value assigned to `a` is never read
drop(b);
})();
}
#[derive(Debug)]
struct MyStruct<'a> {
x: Option<& 'a str>,
y: i32,
}
pub fn nested() {
let mut a : Option<& str>;
a = None;
let mut b : Option<& str>;
b = None;
let mut d = MyStruct{ x: None, y: 1};
let mut e = MyStruct{ x: None, y: 1};
(|| {
(|| {
// This will not trigger a warning for unused variable as
// d.x will be treated as a Non-tracked place
d.x = Some("d1");
d.x = Some("d2");
a = Some("d1"); //~ WARN value assigned to `a` is never read
a = Some("d2");
})();
(move || {
// This will not trigger a warning for unused variable as
//e.x will be treated as a Non-tracked place
e.x = Some("e1");
e.x = Some("e2");
b = Some("e1"); //~ WARN value assigned to `b` is never read
//~| WARN unused variable: `b`
b = Some("e2"); //~ WARN value assigned to `b` is never read
})();
})();
}
fn main() {}
|
