src/tools/clippy/tests/ui/needless_borrowed_ref.rs

   1 // run-rustfix
   2
   3 #![warn(clippy::needless_borrowed_reference)]
   4 #![allow(unused, clippy::needless_borrow)]
   5
   6 fn main() {}
   7
   8 fn should_lint(array: [u8; 4], slice: &[u8], slice_of_refs: &[&u8], vec: Vec<u8>) {
   9     let mut v = Vec::<String>::new();
  10     let _ = v.iter_mut().filter(|&ref a| a.is_empty());
  11
  12     let var = 3;
  13     let thingy = Some(&var);
  14     if let Some(&ref v) = thingy {}
  15
  16     if let &[&ref a, ref b] = slice_of_refs {}
  17
  18     let &[ref a, ..] = &array;
  19     let &[ref a, ref b, ..] = &array;
  20
  21     if let &[ref a, ref b] = slice {}
  22     if let &[ref a, ref b] = &vec[..] {}
  23
  24     if let &[ref a, ref b, ..] = slice {}
  25     if let &[ref a, .., ref b] = slice {}
  26     if let &[.., ref a, ref b] = slice {}
  27 }
  28
  29 fn should_not_lint(array: [u8; 4], slice: &[u8], slice_of_refs: &[&u8], vec: Vec<u8>) {
  30     if let [ref a] = slice {}
  31     if let &[ref a, b] = slice {}
  32     if let &[ref a, .., b] = slice {}
  33
  34     // must not be removed as variables must be bound consistently across | patterns
  35     if let (&[ref a], _) | ([], ref a) = (slice_of_refs, &1u8) {}
  36
  37     let mut var2 = 5;
  38     let thingy2 = Some(&mut var2);
  39     if let Some(&mut ref mut v) = thingy2 {
  40         //          ^ should **not** be linted
  41         // v is borrowed as mutable.
  42         *v = 10;
  43     }
  44     if let Some(&mut ref v) = thingy2 {
  45         //          ^ should **not** be linted
  46         // here, v is borrowed as immutable.
  47         // can't do that:
  48         //*v = 15;
  49     }
  50 }
  51
  52 enum Animal {
  53     Cat(u64),
  54     Dog(u64),
  55 }
  56
  57 fn foo(a: &Animal, b: &Animal) {
  58     match (a, b) {
  59         // lifetime mismatch error if there is no '&ref' before `feature(nll)` stabilization in 1.63
  60         (&Animal::Cat(v), &ref k) | (&ref k, &Animal::Cat(v)) => (),
  61         //                  ^    and   ^ should **not** be linted
  62         (&Animal::Dog(ref a), &Animal::Dog(_)) => (), //              ^ should **not** be linted
  63     }
  64 }