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
|
#![warn(clippy::drop_ref)]
#![allow(clippy::toplevel_ref_arg)]
#![allow(clippy::map_err_ignore)]
#![allow(clippy::unnecessary_wraps, clippy::drop_non_drop)]
use std::mem::drop;
struct SomeStruct;
fn main() {
drop(&SomeStruct);
let mut owned1 = SomeStruct;
drop(&owned1);
drop(&&owned1);
drop(&mut owned1);
drop(owned1); //OK
let reference1 = &SomeStruct;
drop(reference1);
let reference2 = &mut SomeStruct;
drop(reference2);
let ref reference3 = SomeStruct;
drop(reference3);
}
#[allow(dead_code)]
fn test_generic_fn_drop<T>(val: T) {
drop(&val);
drop(val); //OK
}
#[allow(dead_code)]
fn test_similarly_named_function() {
fn drop<T>(_val: T) {}
drop(&SomeStruct); //OK; call to unrelated function which happens to have the same name
std::mem::drop(&SomeStruct);
}
#[derive(Copy, Clone)]
pub struct Error;
fn produce_half_owl_error() -> Result<(), Error> {
Ok(())
}
fn produce_half_owl_ok() -> Result<bool, ()> {
Ok(true)
}
#[allow(dead_code)]
fn test_owl_result() -> Result<(), ()> {
produce_half_owl_error().map_err(|_| ())?;
produce_half_owl_ok().map(|_| ())?;
// the following should not be linted,
// we should not force users to use toilet closures
// to produce owl results when drop is more convenient
produce_half_owl_error().map_err(drop)?;
produce_half_owl_ok().map_err(drop)?;
Ok(())
}
#[allow(dead_code)]
fn test_owl_result_2() -> Result<u8, ()> {
produce_half_owl_error().map_err(|_| ())?;
produce_half_owl_ok().map(|_| ())?;
// the following should not be linted,
// we should not force users to use toilet closures
// to produce owl results when drop is more convenient
produce_half_owl_error().map_err(drop)?;
produce_half_owl_ok().map(drop)?;
Ok(1)
}
#[allow(unused)]
#[allow(clippy::unit_cmp)]
fn issue10122(x: u8) {
// This is a function which returns a reference and has a side-effect, which means
// that calling drop() on the function is considered an idiomatic way of achieving the side-effect
// in a match arm.
fn println_and<T>(t: &T) -> &T {
println!("foo");
t
}
match x {
0 => drop(println_and(&12)), // Don't lint (copy type), we only care about side-effects
1 => drop(println_and(&String::new())), // Don't lint (no copy type), we only care about side-effects
2 => {
drop(println_and(&13)); // Lint, even if we only care about the side-effect, it's already in a block
},
3 if drop(println_and(&14)) == () => (), // Lint, idiomatic use is only in body of `Arm`
4 => drop(&2), // Lint, not a fn/method call
_ => (),
}
}
|
