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
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
//@ run-pass
#![allow(unused_braces)]
#![allow(non_snake_case)]
#![allow(unused_variables)]
// Test that destructors for rvalue temporaries run either at end of
// statement or end of block, as appropriate given the temporary
// lifetime rules.
#![feature(box_patterns)]
static mut FLAGS: u64 = 0;
struct Box<T> { f: T }
struct AddFlags { bits: u64 }
fn AddFlags(bits: u64) -> AddFlags {
AddFlags { bits: bits }
}
fn arg(exp: u64, _x: &AddFlags) {
check_flags(exp);
}
fn pass<T>(v: T) -> T {
v
}
fn check_flags(exp: u64) {
unsafe {
let x = FLAGS;
FLAGS = 0;
println!("flags {}, expected {}", x, exp);
assert_eq!(x, exp);
}
}
impl AddFlags {
fn check_flags<'a>(&'a self, exp: u64) -> &'a AddFlags {
check_flags(exp);
self
}
fn bits(&self) -> u64 {
self.bits
}
}
impl Drop for AddFlags {
fn drop(&mut self) {
unsafe {
FLAGS = FLAGS + self.bits;
}
}
}
macro_rules! end_of_block {
($pat:pat, $expr:expr) => (
{
println!("end_of_block({})", stringify!({let $pat = $expr;}));
{
// Destructor here does not run until exit from the block.
let $pat = $expr;
check_flags(0);
}
check_flags(1);
}
)
}
macro_rules! end_of_stmt {
($pat:pat, $expr:expr) => (
{
println!("end_of_stmt({})", stringify!($expr));
{
// Destructor here run after `let` statement
// terminates.
let $pat = $expr;
check_flags(1);
}
check_flags(0);
}
)
}
pub fn main() {
// In all these cases, we trip over the rules designed to cover
// the case where we are taking addr of rvalue and storing that
// addr into a stack slot, either via `let ref` or via a `&` in
// the initializer.
end_of_block!(_x, AddFlags(1));
end_of_block!(_x, &AddFlags(1));
end_of_block!(_x, & &AddFlags(1));
end_of_block!(_x, Box { f: AddFlags(1) });
end_of_block!(_x, Box { f: &AddFlags(1) });
end_of_block!(_x, Box { f: &AddFlags(1) });
end_of_block!(_x, pass(AddFlags(1)));
end_of_block!(ref _x, AddFlags(1));
end_of_block!(AddFlags { bits: ref _x }, AddFlags(1));
end_of_block!(&AddFlags { bits }, &AddFlags(1));
end_of_block!((_, ref _y), (AddFlags(1), 22));
end_of_block!(box ref _x, std::boxed::Box::new(AddFlags(1)));
end_of_block!(box _x, std::boxed::Box::new(AddFlags(1)));
end_of_block!(_, { { check_flags(0); &AddFlags(1) } });
end_of_block!(_, &((Box { f: AddFlags(1) }).f));
end_of_block!(_, &(([AddFlags(1)])[0]));
// LHS does not create a ref binding, so temporary lives as long
// as statement, and we do not move the AddFlags out:
end_of_stmt!(_, AddFlags(1));
end_of_stmt!((_, _), (AddFlags(1), 22));
// `&` operator appears inside an arg to a function,
// so it is not prolonged:
end_of_stmt!(ref _x, arg(0, &AddFlags(1)));
// autoref occurs inside receiver, so temp lifetime is not
// prolonged:
end_of_stmt!(ref _x, AddFlags(1).check_flags(0).bits());
// No reference is created on LHS, thus RHS is moved into
// a temporary that lives just as long as the statement.
end_of_stmt!(AddFlags { bits }, AddFlags(1));
}
|
