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1 | // run-rustfix |
2 | ||
3 | #![warn(clippy::while_let_on_iterator)] | |
4 | #![allow(clippy::never_loop, unreachable_code, unused_mut)] | |
5 | #![feature(or_patterns)] | |
6 | ||
7 | fn base() { | |
8 | let mut iter = 1..20; | |
9 | for x in iter { | |
10 | println!("{}", x); | |
11 | } | |
12 | ||
13 | let mut iter = 1..20; | |
14 | for x in iter { | |
15 | println!("{}", x); | |
16 | } | |
17 | ||
18 | let mut iter = 1..20; | |
19 | for _ in iter {} | |
20 | ||
21 | let mut iter = 1..20; | |
22 | while let None = iter.next() {} // this is fine (if nonsensical) | |
23 | ||
24 | let mut iter = 1..20; | |
25 | if let Some(x) = iter.next() { | |
26 | // also fine | |
27 | println!("{}", x) | |
28 | } | |
29 | ||
30 | // the following shouldn't warn because it can't be written with a for loop | |
31 | let mut iter = 1u32..20; | |
32 | while let Some(_) = iter.next() { | |
33 | println!("next: {:?}", iter.next()) | |
34 | } | |
35 | ||
36 | // neither can this | |
37 | let mut iter = 1u32..20; | |
38 | while let Some(_) = iter.next() { | |
39 | println!("next: {:?}", iter.next()); | |
40 | } | |
41 | ||
42 | // or this | |
43 | let mut iter = 1u32..20; | |
44 | while let Some(_) = iter.next() { | |
45 | break; | |
46 | } | |
47 | println!("Remaining iter {:?}", iter); | |
48 | ||
49 | // or this | |
50 | let mut iter = 1u32..20; | |
51 | while let Some(_) = iter.next() { | |
52 | iter = 1..20; | |
53 | } | |
54 | } | |
55 | ||
56 | // Issue #1188 | |
57 | fn refutable() { | |
58 | let a = [42, 1337]; | |
59 | let mut b = a.iter(); | |
60 | ||
61 | // consume all the 42s | |
62 | while let Some(&42) = b.next() {} | |
63 | ||
64 | let a = [(1, 2, 3)]; | |
65 | let mut b = a.iter(); | |
66 | ||
67 | while let Some(&(1, 2, 3)) = b.next() {} | |
68 | ||
69 | let a = [Some(42)]; | |
70 | let mut b = a.iter(); | |
71 | ||
72 | while let Some(&None) = b.next() {} | |
73 | ||
74 | /* This gives “refutable pattern in `for` loop binding: `&_` not covered” | |
75 | for &42 in b {} | |
76 | for &(1, 2, 3) in b {} | |
77 | for &Option::None in b.next() {} | |
78 | // */ | |
79 | } | |
80 | ||
81 | fn refutable2() { | |
82 | // Issue 3780 | |
83 | { | |
84 | let v = vec![1, 2, 3]; | |
85 | let mut it = v.windows(2); | |
86 | while let Some([x, y]) = it.next() { | |
87 | println!("x: {}", x); | |
88 | println!("y: {}", y); | |
89 | } | |
90 | ||
91 | let mut it = v.windows(2); | |
92 | while let Some([x, ..]) = it.next() { | |
93 | println!("x: {}", x); | |
94 | } | |
95 | ||
96 | let mut it = v.windows(2); | |
97 | while let Some([.., y]) = it.next() { | |
98 | println!("y: {}", y); | |
99 | } | |
100 | ||
101 | let mut it = v.windows(2); | |
102 | for [..] in it {} | |
103 | ||
104 | let v = vec![[1], [2], [3]]; | |
105 | let mut it = v.iter(); | |
106 | while let Some([1]) = it.next() {} | |
107 | ||
108 | let mut it = v.iter(); | |
109 | for [_x] in it {} | |
110 | } | |
111 | ||
112 | // binding | |
113 | { | |
114 | let v = vec![1, 2, 3]; | |
115 | let mut it = v.iter(); | |
116 | while let Some(x @ 1) = it.next() { | |
117 | println!("{}", x); | |
118 | } | |
119 | ||
120 | let v = vec![[1], [2], [3]]; | |
121 | let mut it = v.iter(); | |
122 | for x @ [_] in it { | |
123 | println!("{:?}", x); | |
124 | } | |
125 | } | |
126 | ||
127 | // false negative | |
128 | { | |
129 | let v = vec![1, 2, 3]; | |
130 | let mut it = v.iter().map(Some); | |
131 | while let Some(Some(_) | None) = it.next() { | |
132 | println!("1"); | |
133 | } | |
134 | } | |
135 | } | |
136 | ||
137 | fn nested_loops() { | |
138 | let a = [42, 1337]; | |
139 | let mut y = a.iter(); | |
140 | loop { | |
141 | // x is reused, so don't lint here | |
142 | while let Some(_) = y.next() {} | |
143 | } | |
144 | ||
145 | let mut y = a.iter(); | |
146 | for _ in 0..2 { | |
147 | while let Some(_) = y.next() { | |
148 | // y is reused, don't lint | |
149 | } | |
150 | } | |
151 | ||
152 | loop { | |
153 | let mut y = a.iter(); | |
154 | for _ in y { | |
155 | // use a for loop here | |
156 | } | |
157 | } | |
158 | } | |
159 | ||
160 | fn issue1121() { | |
161 | use std::collections::HashSet; | |
162 | let mut values = HashSet::new(); | |
163 | values.insert(1); | |
164 | ||
165 | while let Some(&value) = values.iter().next() { | |
166 | values.remove(&value); | |
167 | } | |
168 | } | |
169 | ||
170 | fn issue2965() { | |
171 | // This should not cause an ICE and suggest: | |
172 | // | |
173 | // for _ in values.iter() {} | |
174 | // | |
175 | use std::collections::HashSet; | |
176 | let mut values = HashSet::new(); | |
177 | values.insert(1); | |
178 | ||
179 | while let Some(..) = values.iter().next() {} | |
180 | } | |
181 | ||
182 | fn issue3670() { | |
183 | let array = [Some(0), None, Some(1)]; | |
184 | let mut iter = array.iter(); | |
185 | ||
186 | while let Some(elem) = iter.next() { | |
187 | let _ = elem.or_else(|| *iter.next()?); | |
188 | } | |
189 | } | |
190 | ||
191 | fn issue1654() { | |
192 | // should not lint if the iterator is generated on every iteration | |
193 | use std::collections::HashSet; | |
194 | let mut values = HashSet::new(); | |
195 | values.insert(1); | |
196 | ||
197 | while let Some(..) = values.iter().next() { | |
198 | values.remove(&1); | |
199 | } | |
200 | ||
201 | while let Some(..) = values.iter().map(|x| x + 1).next() {} | |
202 | ||
203 | let chars = "Hello, World!".char_indices(); | |
204 | while let Some((i, ch)) = chars.clone().next() { | |
205 | println!("{}: {}", i, ch); | |
206 | } | |
207 | } | |
208 | ||
209 | fn main() { | |
210 | base(); | |
211 | refutable(); | |
212 | refutable2(); | |
213 | nested_loops(); | |
214 | issue1121(); | |
215 | issue2965(); | |
216 | issue3670(); | |
217 | issue1654(); | |
218 | } |