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
93
94
95
96
97
98
99
100
101
102
103
104
105
|
// run-pass
#![feature(box_syntax)]
struct Fat<T: ?Sized> {
f1: isize,
f2: &'static str,
ptr: T
}
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct Bar;
#[derive(Copy, Clone, PartialEq, Eq)]
struct Bar1 {
f: isize
}
trait ToBar {
fn to_bar(&self) -> Bar;
fn to_val(&self) -> isize;
}
impl ToBar for Bar {
fn to_bar(&self) -> Bar {
*self
}
fn to_val(&self) -> isize {
0
}
}
impl ToBar for Bar1 {
fn to_bar(&self) -> Bar {
Bar
}
fn to_val(&self) -> isize {
self.f
}
}
// x is a fat pointer
fn foo(x: &Fat<dyn ToBar>) {
assert_eq!(x.f1, 5);
assert_eq!(x.f2, "some str");
assert_eq!(x.ptr.to_bar(), Bar);
assert_eq!(x.ptr.to_val(), 42);
let y = &x.ptr;
assert_eq!(y.to_bar(), Bar);
assert_eq!(y.to_val(), 42);
}
fn bar(x: &dyn ToBar) {
assert_eq!(x.to_bar(), Bar);
assert_eq!(x.to_val(), 42);
}
fn baz(x: &Fat<Fat<dyn ToBar>>) {
assert_eq!(x.f1, 5);
assert_eq!(x.f2, "some str");
assert_eq!(x.ptr.f1, 8);
assert_eq!(x.ptr.f2, "deep str");
assert_eq!(x.ptr.ptr.to_bar(), Bar);
assert_eq!(x.ptr.ptr.to_val(), 42);
let y = &x.ptr.ptr;
assert_eq!(y.to_bar(), Bar);
assert_eq!(y.to_val(), 42);
}
pub fn main() {
let f1 = Fat { f1: 5, f2: "some str", ptr: Bar1 {f :42} };
foo(&f1);
let f2 = &f1;
foo(f2);
let f3: &Fat<dyn ToBar> = f2;
foo(f3);
let f4: &Fat<dyn ToBar> = &f1;
foo(f4);
let f5: &Fat<dyn ToBar> = &Fat { f1: 5, f2: "some str", ptr: Bar1 {f :42} };
foo(f5);
// Zero size object.
let f6: &Fat<dyn ToBar> = &Fat { f1: 5, f2: "some str", ptr: Bar };
assert_eq!(f6.ptr.to_bar(), Bar);
// &*
//
let f7: Box<dyn ToBar> = Box::new(Bar1 {f :42});
bar(&*f7);
// Deep nesting
let f1 =
Fat { f1: 5, f2: "some str", ptr: Fat { f1: 8, f2: "deep str", ptr: Bar1 {f :42}} };
baz(&f1);
let f2 = &f1;
baz(f2);
let f3: &Fat<Fat<dyn ToBar>> = f2;
baz(f3);
let f4: &Fat<Fat<dyn ToBar>> = &f1;
baz(f4);
let f5: &Fat<Fat<dyn ToBar>> =
&Fat { f1: 5, f2: "some str", ptr: Fat { f1: 8, f2: "deep str", ptr: Bar1 {f :42}} };
baz(f5);
}
|
