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
|
#![allow(unused)]
#![warn(clippy::let_and_return)]
use std::cell::RefCell;
fn test() -> i32 {
let _y = 0; // no warning
let x = 5;
x
//~^ ERROR: returning the result of a `let` binding from a block
//~| NOTE: `-D clippy::let-and-return` implied by `-D warnings`
}
fn test_inner() -> i32 {
if true {
let x = 5;
x
//~^ ERROR: returning the result of a `let` binding from a block
} else {
0
}
}
fn test_nowarn_1() -> i32 {
let mut x = 5;
x += 1;
x
}
fn test_nowarn_2() -> i32 {
let x = 5;
x + 1
}
fn test_nowarn_3() -> (i32, i32) {
// this should technically warn, but we do not compare complex patterns
let (x, y) = (5, 9);
(x, y)
}
fn test_nowarn_4() -> i32 {
// this should technically warn, but not b/c of clippy::let_and_return, but b/c of useless type
let x: i32 = 5;
x
}
fn test_nowarn_5(x: i16) -> u16 {
#[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
let x = x as u16;
x
}
// False positive example
trait Decode {
fn decode<D: std::io::Read>(d: D) -> Result<Self, ()>
where
Self: Sized;
}
macro_rules! tuple_encode {
($($x:ident),*) => (
impl<$($x: Decode),*> Decode for ($($x),*) {
#[inline]
#[allow(non_snake_case)]
fn decode<D: std::io::Read>(mut d: D) -> Result<Self, ()> {
// Shouldn't trigger lint
Ok(($({let $x = Decode::decode(&mut d)?; $x }),*))
}
}
);
}
fn issue_3792() -> String {
use std::io::{self, BufRead, Stdin};
let stdin = io::stdin();
// `Stdin::lock` returns `StdinLock<'static>` so `line` doesn't borrow from `stdin`
// https://github.com/rust-lang/rust/pull/93965
let line = stdin.lock().lines().next().unwrap().unwrap();
line
//~^ ERROR: returning the result of a `let` binding from a block
}
tuple_encode!(T0, T1, T2, T3, T4, T5, T6, T7);
mod no_lint_if_stmt_borrows {
use std::cell::RefCell;
use std::rc::{Rc, Weak};
struct Bar;
impl Bar {
fn new() -> Self {
Bar {}
}
fn baz(&self) -> u32 {
0
}
}
fn issue_3324(value: Weak<RefCell<Bar>>) -> u32 {
let value = value.upgrade().unwrap();
let ret = value.borrow().baz();
ret
}
fn borrows_in_closure(value: Weak<RefCell<Bar>>) -> u32 {
fn f(mut x: impl FnMut() -> u32) -> impl FnMut() -> u32 {
x
}
let value = value.upgrade().unwrap();
let ret = f(|| value.borrow().baz())();
ret
}
mod free_function {
struct Inner;
struct Foo<'a> {
inner: &'a Inner,
}
impl Drop for Foo<'_> {
fn drop(&mut self) {}
}
impl<'a> Foo<'a> {
fn new(inner: &'a Inner) -> Self {
Self { inner }
}
fn value(&self) -> i32 {
42
}
}
fn some_foo(inner: &Inner) -> Foo<'_> {
Foo { inner }
}
fn test() -> i32 {
let x = Inner {};
let value = some_foo(&x).value();
value
}
fn test2() -> i32 {
let x = Inner {};
let value = Foo::new(&x).value();
value
}
}
}
mod issue_5729 {
use std::sync::Arc;
trait Foo {}
trait FooStorage {
fn foo_cloned(&self) -> Arc<dyn Foo>;
}
struct FooStorageImpl<T: Foo> {
foo: Arc<T>,
}
impl<T: Foo + 'static> FooStorage for FooStorageImpl<T> {
fn foo_cloned(&self) -> Arc<dyn Foo> {
let clone = Arc::clone(&self.foo);
clone
//~^ ERROR: returning the result of a `let` binding from a block
}
}
}
mod issue_11335 {
pub enum E<T> {
A(T),
B(T),
}
impl<T> E<T> {
pub fn inner(&self) -> &T {
let result = match self {
E::A(x) => x,
E::B(x) => x,
};
result
//~^ ERROR: returning the result of a `let` binding from a block
}
}
}
// https://github.com/rust-lang/rust-clippy/issues/11167
macro_rules! fn_in_macro {
($b:block) => {
fn f() -> usize $b
}
}
fn_in_macro!({
return 1;
});
fn main() {}
|
