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

   1 #![feature(plugin)]
   2 #![plugin(clippy)]
   3
   4 #![warn(let_unit_value)]
   5 #![allow(unused_variables)]
   6
   7 macro_rules! let_and_return {
   8     ($n:expr) => {{
   9         let ret = $n;
  10     }}
  11 }
  12
  13 fn main() {
  14     let _x = println!("x");
  15     let _y = 1;   // this is fine
  16     let _z = ((), 1);  // this as well
  17     if true {
  18         let _a = ();
  19     }
  20
  21     consume_units_with_for_loop(); // should be fine as well
  22
  23     let_and_return!(()) // should be fine
  24 }
  25
  26 // Related to issue #1964
  27 fn consume_units_with_for_loop() {
  28     // `for_let_unit` lint should not be triggered by consuming them using for loop.
  29     let v = vec![(), (), ()];
  30     let mut count = 0;
  31     for _ in v {
  32         count += 1;
  33     }
  34     assert_eq!(count, 3);
  35
  36     // Same for consuming from some other Iterator<Item = ()>.
  37     let (tx, rx) = ::std::sync::mpsc::channel();
  38     tx.send(()).unwrap();
  39     drop(tx);
  40
  41     count = 0;
  42     for _ in rx.iter() {
  43         count += 1;
  44     }
  45     assert_eq!(count, 1);
  46 }
  47
  48 #[derive(Copy, Clone)]
  49 pub struct ContainsUnit(()); // should be fine