rust-clippy/tests/ui/needless_borrow.rs
2022-08-16 18:34:51 -04:00

300 lines
6.4 KiB
Rust

// run-rustfix
#![feature(custom_inner_attributes, lint_reasons)]
#[warn(clippy::all, clippy::needless_borrow)]
#[allow(unused_variables, clippy::unnecessary_mut_passed)]
fn main() {
let a = 5;
let ref_a = &a;
let _ = x(&a); // no warning
let _ = x(&&a); // warn
let mut b = 5;
mut_ref(&mut b); // no warning
mut_ref(&mut &mut b); // warn
let s = &String::from("hi");
let s_ident = f(&s); // should not error, because `&String` implements Copy, but `String` does not
let g_val = g(&Vec::new()); // should not error, because `&Vec<T>` derefs to `&[T]`
let vec = Vec::new();
let vec_val = g(&vec); // should not error, because `&Vec<T>` derefs to `&[T]`
h(&"foo"); // should not error, because the `&&str` is required, due to `&Trait`
let garbl = match 42 {
44 => &a,
45 => {
println!("foo");
&&a
},
46 => &&a,
47 => {
println!("foo");
loop {
println!("{}", a);
if a == 25 {
break &ref_a;
}
}
},
_ => panic!(),
};
let _ = x(&&&a);
let _ = x(&mut &&a);
let _ = x(&&&mut b);
let _ = x(&&ref_a);
{
let b = &mut b;
x(&b);
}
// Issue #8191
let mut x = 5;
let mut x = &mut x;
mut_ref(&mut x);
mut_ref(&mut &mut x);
let y: &mut i32 = &mut x;
let y: &mut i32 = &mut &mut x;
let y = match 0 {
// Don't lint. Removing the borrow would move 'x'
0 => &mut x,
_ => &mut *x,
};
let y: &mut i32 = match 0 {
// Lint here. The type given above triggers auto-borrow.
0 => &mut x,
_ => &mut *x,
};
fn ref_mut_i32(_: &mut i32) {}
ref_mut_i32(match 0 {
// Lint here. The type given above triggers auto-borrow.
0 => &mut x,
_ => &mut *x,
});
// use 'x' after to make sure it's still usable in the fixed code.
*x = 5;
let s = String::new();
// let _ = (&s).len();
// let _ = (&s).capacity();
// let _ = (&&s).capacity();
let x = (1, 2);
let _ = (&x).0;
let x = &x as *const (i32, i32);
let _ = unsafe { (&*x).0 };
// Issue #8367
trait Foo {
fn foo(self);
}
impl Foo for &'_ () {
fn foo(self) {}
}
(&()).foo(); // Don't lint. `()` doesn't implement `Foo`
(&&()).foo();
impl Foo for i32 {
fn foo(self) {}
}
impl Foo for &'_ i32 {
fn foo(self) {}
}
(&5).foo(); // Don't lint. `5` will call `<i32 as Foo>::foo`
(&&5).foo();
trait FooRef {
fn foo_ref(&self);
}
impl FooRef for () {
fn foo_ref(&self) {}
}
impl FooRef for &'_ () {
fn foo_ref(&self) {}
}
(&&()).foo_ref(); // Don't lint. `&()` will call `<() as FooRef>::foo_ref`
struct S;
impl From<S> for u32 {
fn from(s: S) -> Self {
(&s).into()
}
}
impl From<&S> for u32 {
fn from(s: &S) -> Self {
0
}
}
let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap();
let _ = std::path::Path::new(".").join(&&".");
deref_target_is_x(&X);
multiple_constraints(&[[""]]);
multiple_constraints_normalizes_to_same(&X, X);
let _ = Some("").unwrap_or(&"");
only_sized(&""); // Don't lint. `Sized` is only bound
let _ = std::any::Any::type_id(&""); // Don't lint. `Any` is only bound
let _ = Box::new(&""); // Don't lint. Type parameter appears in return type
ref_as_ref_path(&""); // Don't lint. Argument type is not a type parameter
refs_only(&()); // Don't lint. `&T` implements trait, but `T` doesn't
multiple_constraints_normalizes_to_different(&[[""]], &[""]); // Don't lint. Projected type appears in arguments
}
#[allow(clippy::needless_borrowed_reference)]
fn x(y: &i32) -> i32 {
*y
}
fn mut_ref(y: &mut i32) {
*y = 5;
}
fn f<T: Copy>(y: &T) -> T {
*y
}
fn g(y: &[u8]) -> u8 {
y[0]
}
trait Trait {}
impl<'a> Trait for &'a str {}
fn h(_: &dyn Trait) {}
#[allow(dead_code)]
fn check_expect_suppression() {
let a = 5;
#[expect(clippy::needless_borrow)]
let _ = x(&&a);
}
#[allow(dead_code)]
mod issue9160 {
pub struct S<F> {
f: F,
}
impl<T, F> S<F>
where
F: Fn() -> T,
{
fn calls_field(&self) -> T {
(&self.f)()
}
}
impl<T, F> S<F>
where
F: FnMut() -> T,
{
fn calls_mut_field(&mut self) -> T {
(&mut self.f)()
}
}
}
#[derive(Clone, Copy)]
struct X;
impl std::ops::Deref for X {
type Target = X;
fn deref(&self) -> &Self::Target {
self
}
}
fn deref_target_is_x<T>(_: T)
where
T: std::ops::Deref<Target = X>,
{
}
fn multiple_constraints<T, U, V, X, Y>(_: T)
where
T: IntoIterator<Item = U> + IntoIterator<Item = X>,
U: IntoIterator<Item = V>,
V: AsRef<str>,
X: IntoIterator<Item = Y>,
Y: AsRef<std::ffi::OsStr>,
{
}
fn multiple_constraints_normalizes_to_same<T, U, V>(_: T, _: V)
where
T: std::ops::Deref<Target = U>,
U: std::ops::Deref<Target = V>,
{
}
fn only_sized<T>(_: T) {}
fn ref_as_ref_path<T: 'static>(_: &'static T)
where
&'static T: AsRef<std::path::Path>,
{
}
trait RefsOnly {
type Referent;
}
impl<T> RefsOnly for &T {
type Referent = T;
}
fn refs_only<T, U>(_: T)
where
T: RefsOnly<Referent = U>,
{
}
fn multiple_constraints_normalizes_to_different<T, U, V>(_: T, _: U)
where
T: IntoIterator<Item = U>,
U: IntoIterator<Item = V>,
V: AsRef<str>,
{
}
// https://github.com/rust-lang/rust-clippy/pull/9136#pullrequestreview-1037379321
#[allow(dead_code)]
mod copyable_iterator {
#[derive(Clone, Copy)]
struct Iter;
impl Iterator for Iter {
type Item = ();
fn next(&mut self) -> Option<Self::Item> {
None
}
}
fn takes_iter(_: impl Iterator) {}
fn dont_warn(mut x: Iter) {
takes_iter(&mut x);
}
fn warn(mut x: &mut Iter) {
takes_iter(&mut x)
}
}
mod under_msrv {
#![allow(dead_code)]
#![clippy::msrv = "1.52.0"]
fn foo() {
let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap();
}
}
mod meets_msrv {
#![allow(dead_code)]
#![clippy::msrv = "1.53.0"]
fn foo() {
let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap();
}
}