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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
|
#![deny(clippy::useless_asref)]
#![allow(
clippy::explicit_auto_deref,
clippy::uninlined_format_args,
clippy::map_clone,
clippy::needless_pass_by_ref_mut,
clippy::redundant_closure
)]
use std::fmt::Debug;
use std::ops::Deref;
use std::rc::{Rc, Weak as RcWeak};
use std::sync::{Arc, Weak as ArcWeak};
struct FakeAsRef;
#[allow(clippy::should_implement_trait)]
impl FakeAsRef {
fn as_ref(&self) -> &Self {
self
}
}
struct MoreRef;
impl<'a, 'b, 'c> AsRef<&'a &'b &'c MoreRef> for MoreRef {
fn as_ref(&self) -> &&'a &'b &'c MoreRef {
&&&&MoreRef
}
}
fn foo_rstr(x: &str) {
println!("{:?}", x);
}
fn foo_rslice(x: &[i32]) {
println!("{:?}", x);
}
fn foo_mrslice(x: &mut [i32]) {
println!("{:?}", x);
}
fn foo_rrrrmr(_: &&&&MoreRef) {
println!("so many refs");
}
fn not_ok() {
let rstr: &str = "hello";
let mut mrslice: &mut [i32] = &mut [1, 2, 3];
{
let rslice: &[i32] = &*mrslice;
foo_rstr(rstr.as_ref());
//~^ useless_asref
foo_rstr(rstr);
foo_rslice(rslice.as_ref());
//~^ useless_asref
foo_rslice(rslice);
}
{
foo_mrslice(mrslice.as_mut());
//~^ useless_asref
foo_mrslice(mrslice);
foo_rslice(mrslice.as_ref());
//~^ useless_asref
foo_rslice(mrslice);
}
{
let rrrrrstr = &&&&rstr;
let rrrrrslice = &&&&&*mrslice;
foo_rslice(rrrrrslice.as_ref());
//~^ useless_asref
foo_rslice(rrrrrslice);
foo_rstr(rrrrrstr.as_ref());
//~^ useless_asref
foo_rstr(rrrrrstr);
}
{
let mrrrrrslice = &mut &mut &mut &mut mrslice;
foo_mrslice(mrrrrrslice.as_mut());
//~^ useless_asref
foo_mrslice(mrrrrrslice);
foo_rslice(mrrrrrslice.as_ref());
//~^ useless_asref
foo_rslice(mrrrrrslice);
}
#[allow(unused_parens, clippy::double_parens, clippy::needless_borrow)]
foo_rrrrmr((&&&&MoreRef).as_ref());
//~^ useless_asref
generic_not_ok(mrslice);
generic_ok(mrslice);
}
fn ok() {
let string = "hello".to_owned();
let mut arr = [1, 2, 3];
let mut vec = vec![1, 2, 3];
{
foo_rstr(string.as_ref());
foo_rslice(arr.as_ref());
foo_rslice(vec.as_ref());
}
{
foo_mrslice(arr.as_mut());
foo_mrslice(vec.as_mut());
}
{
let rrrrstring = &&&&string;
let rrrrarr = &&&&arr;
let rrrrvec = &&&&vec;
foo_rstr(rrrrstring.as_ref());
foo_rslice(rrrrarr.as_ref());
foo_rslice(rrrrvec.as_ref());
}
{
let mrrrrarr = &mut &mut &mut &mut arr;
let mrrrrvec = &mut &mut &mut &mut vec;
foo_mrslice(mrrrrarr.as_mut());
foo_mrslice(mrrrrvec.as_mut());
}
FakeAsRef.as_ref();
foo_rrrrmr(MoreRef.as_ref());
generic_not_ok(arr.as_mut());
generic_ok(&mut arr);
}
fn foo_mrt<T: Debug + ?Sized>(t: &mut T) {
println!("{:?}", t);
}
fn foo_rt<T: Debug + ?Sized>(t: &T) {
println!("{:?}", t);
}
fn generic_not_ok<T: AsMut<T> + AsRef<T> + Debug + ?Sized>(mrt: &mut T) {
foo_mrt(mrt.as_mut());
//~^ useless_asref
foo_mrt(mrt);
foo_rt(mrt.as_ref());
//~^ useless_asref
foo_rt(mrt);
}
fn generic_ok<U: AsMut<T> + AsRef<T> + ?Sized, T: Debug + ?Sized>(mru: &mut U) {
foo_mrt(mru.as_mut());
foo_rt(mru.as_ref());
}
fn foo() {
let x = Some(String::new());
let z = x.as_ref().map(String::clone);
//~^ useless_asref
let z = x.as_ref().map(|z| z.clone());
//~^ useless_asref
let z = x.as_ref().map(|z| String::clone(z));
//~^ useless_asref
}
mod issue12135 {
pub struct Struct {
field: Option<InnerStruct>,
}
#[derive(Clone)]
pub struct Foo;
#[derive(Clone)]
struct InnerStruct {
x: Foo,
}
impl InnerStruct {
fn method(&self) -> &Foo {
&self.x
}
}
pub fn f(x: &Struct) -> Option<Foo> {
x.field.as_ref().map(|v| v.clone());
//~^ useless_asref
x.field.as_ref().map(Clone::clone);
//~^ useless_asref
x.field.as_ref().map(|v| Clone::clone(v));
//~^ useless_asref
// https://github.com/rust-lang/rust-clippy/pull/12136#discussion_r1451565223
#[allow(clippy::clone_on_copy)]
Some(1).as_ref().map(|&x| x.clone());
//~^ useless_asref
x.field.as_ref().map(|v| v.method().clone())
}
}
fn issue_12528() {
struct Foo;
let opt = Some(Arc::new(Foo));
let _ = opt.as_ref().map(Arc::clone);
let opt = Some(Rc::new(Foo));
let _ = opt.as_ref().map(Rc::clone);
let opt = Some(Arc::downgrade(&Arc::new(Foo)));
let _ = opt.as_ref().map(ArcWeak::clone);
let opt = Some(Rc::downgrade(&Rc::new(Foo)));
let _ = opt.as_ref().map(RcWeak::clone);
}
fn issue_14088() {
let s = Some("foo");
let _: Option<&str> = s.as_ref().map(|x| x.as_ref());
}
pub struct Wrap<T> {
inner: T,
}
impl<T> Deref for Wrap<T> {
type Target = T;
fn deref(&self) -> &Self::Target {
&self.inner
}
}
struct NonCloneableError;
pub struct Issue12357 {
current: Option<Wrap<Arc<u32>>>,
}
impl Issue12357 {
fn f(&self) -> Option<Arc<u32>> {
self.current.as_ref().map(|p| Arc::clone(p))
}
fn g(&self) {
let result: Result<String, NonCloneableError> = Ok("Hello".to_string());
let cloned = result.as_ref().map(|s| s.clone());
}
}
fn issue_14828() {
pub trait T {
fn as_ref(&self) {}
}
impl T for () {}
().as_ref();
}
fn main() {
not_ok();
ok();
}
|
