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|
//@ edition:2018
// Exercise the unused_mut attribute in some positive and negative cases
#![warn(unused_mut)]
async fn baz_async(
mut a: i32,
//~^ WARN: variable does not need to be mutable
#[allow(unused_mut)] mut b: i32,
) {}
fn baz(
mut a: i32,
//~^ WARN: variable does not need to be mutable
#[allow(unused_mut)] mut b: i32,
#[allow(unused_mut)] (mut c, d): (i32, i32)
) {}
struct RefStruct {}
impl RefStruct {
async fn baz_async(
mut a: i32,
//~^ WARN: variable does not need to be mutable
#[allow(unused_mut)] mut b: i32,
) {}
fn baz(
&self,
mut a: i32,
//~^ WARN: variable does not need to be mutable
#[allow(unused_mut)] mut b: i32,
#[allow(unused_mut)] (mut c, d): (i32, i32)
) {}
}
trait RefTrait {
fn baz(
&self,
mut a: i32,
//~^ WARN: variable does not need to be mutable
#[allow(unused_mut)] mut b: i32,
#[allow(unused_mut)] (mut c, d): (i32, i32)
) {}
}
impl RefTrait for () {
fn baz(
&self,
mut a: i32,
//~^ WARN: variable does not need to be mutable
#[allow(unused_mut)] mut b: i32,
#[allow(unused_mut)] (mut c, d): (i32, i32)
) {}
}
fn main() {
let _ = async move |
mut a: i32,
//~^ WARN: variable does not need to be mutable
#[allow(unused_mut)] mut b: i32,
| {};
let _ = |
mut a: i32,
//~^ WARN: variable does not need to be mutable
#[allow(unused_mut)] mut b: i32,
#[allow(unused_mut)] (mut c, d): (i32, i32)
| {};
// negative cases
let mut a = 3; //~ WARN: variable does not need to be mutable
let mut a = 2; //~ WARN: variable does not need to be mutable
let mut b = 3; //~ WARN: variable does not need to be mutable
let mut a = vec![3]; //~ WARN: variable does not need to be mutable
let (mut a, b) = (1, 2); //~ WARN: variable does not need to be mutable
let mut a; //~ WARN: variable does not need to be mutable
a = 3;
let mut b; //~ WARN: variable does not need to be mutable
if true {
b = 3;
} else {
b = 4;
}
match 30 {
mut x => {} //~ WARN: variable does not need to be mutable
}
match (30, 2) {
// FIXME: Here's a false positive,
// shouldn't be removed `mut` not to be bound with a different way.
(mut x, 1) | //~ WARN: variable does not need to be mutable
(mut x, 2) |
(mut x, 3) => {
}
_ => {}
}
let x = |mut y: isize| 10; //~ WARN: variable does not need to be mutable
fn what(mut foo: isize) {} //~ WARN: variable does not need to be mutable
let mut a = &mut 5; //~ WARN: variable does not need to be mutable
*a = 4;
let mut a = 5;
let mut b = (&mut a,); //~ WARN: variable does not need to be mutable
*b.0 = 4;
let mut x = &mut 1; //~ WARN: variable does not need to be mutable
let mut f = || {
*x += 1;
};
f();
fn mut_ref_arg(mut arg : &mut [u8]) -> &mut [u8] {
&mut arg[..] //~^ WARN: variable does not need to be mutable
}
let mut v : &mut Vec<()> = &mut vec![]; //~ WARN: variable does not need to be mutable
v.push(());
// positive cases
let mut a = 2;
a = 3;
let mut a = Vec::new();
a.push(3);
let mut a = Vec::new();
callback(|| {
a.push(3);
});
let mut a = Vec::new();
callback(|| {
callback(|| {
a.push(3);
});
});
let (mut a, b) = (1, 2);
a = 34;
match 30 {
mut x => {
x = 21;
}
}
match (30, 2) {
(mut x, 1) |
(mut x, 2) |
(mut x, 3) => {
x = 21
}
_ => {}
}
// Attribute should be respected on match arms
match 0 {
#[allow(unused_mut)]
mut x => {
let mut y = 1;
},
}
let x = |mut y: isize| y = 32;
fn nothing(mut foo: isize) { foo = 37; }
// leading underscore should avoid the warning, just like the
// unused variable lint.
let mut _allowed = 1;
let mut raw_address_of_mut = 1; // OK
let mut_ptr = &raw mut raw_address_of_mut;
let mut raw_address_of_const = 1; //~ WARN: variable does not need to be mutable
let const_ptr = &raw const raw_address_of_const;
}
fn callback<F>(f: F) where F: FnOnce() {}
// make sure the lint attribute can be turned off
#[allow(unused_mut)]
fn foo(mut a: isize) {
let mut a = 3;
let mut b = vec![2];
}
// make sure the lint attribute can be turned off on let statements
#[deny(unused_mut)]
fn bar() {
#[allow(unused_mut)]
let mut a = 3;
let mut b = vec![2]; //~ ERROR: variable does not need to be mutable
}
struct Arg(i32);
// Regression test for https://github.com/rust-lang/rust/issues/110849
fn write_through_reference(mut arg: &mut Arg) {
//~^ WARN: variable does not need to be mutable
arg.0 = 1
}
|
