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

   1 // run-rustfix
   2
   3 #![feature(custom_inner_attributes)]
   4 #![allow(unused)]
   5 #![warn(
   6     clippy::all,
   7     clippy::style,
   8     clippy::mem_replace_option_with_none,
   9     clippy::mem_replace_with_default
  10 )]
  11
  12 use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList, VecDeque};
  13 use std::mem;
  14
  15 fn replace_option_with_none() {
  16     let mut an_option = Some(1);
  17     let _ = mem::replace(&mut an_option, None);
  18     let an_option = &mut Some(1);
  19     let _ = mem::replace(an_option, None);
  20 }
  21
  22 fn replace_with_default() {
  23     let mut s = String::from("foo");
  24     let _ = std::mem::replace(&mut s, String::default());
  25
  26     let s = &mut String::from("foo");
  27     let _ = std::mem::replace(s, String::default());
  28     let _ = std::mem::replace(s, Default::default());
  29
  30     let mut v = vec![123];
  31     let _ = std::mem::replace(&mut v, Vec::default());
  32     let _ = std::mem::replace(&mut v, Default::default());
  33     let _ = std::mem::replace(&mut v, Vec::new());
  34     let _ = std::mem::replace(&mut v, vec![]);
  35
  36     let mut hash_map: HashMap<i32, i32> = HashMap::new();
  37     let _ = std::mem::replace(&mut hash_map, HashMap::new());
  38
  39     let mut btree_map: BTreeMap<i32, i32> = BTreeMap::new();
  40     let _ = std::mem::replace(&mut btree_map, BTreeMap::new());
  41
  42     let mut vd: VecDeque<i32> = VecDeque::new();
  43     let _ = std::mem::replace(&mut vd, VecDeque::new());
  44
  45     let mut hash_set: HashSet<&str> = HashSet::new();
  46     let _ = std::mem::replace(&mut hash_set, HashSet::new());
  47
  48     let mut btree_set: BTreeSet<&str> = BTreeSet::new();
  49     let _ = std::mem::replace(&mut btree_set, BTreeSet::new());
  50
  51     let mut list: LinkedList<i32> = LinkedList::new();
  52     let _ = std::mem::replace(&mut list, LinkedList::new());
  53
  54     let mut binary_heap: BinaryHeap<i32> = BinaryHeap::new();
  55     let _ = std::mem::replace(&mut binary_heap, BinaryHeap::new());
  56
  57     let mut tuple = (vec![1, 2], BinaryHeap::<i32>::new());
  58     let _ = std::mem::replace(&mut tuple, (vec![], BinaryHeap::new()));
  59
  60     let mut refstr = "hello";
  61     let _ = std::mem::replace(&mut refstr, "");
  62
  63     let mut slice: &[i32] = &[1, 2, 3];
  64     let _ = std::mem::replace(&mut slice, &[]);
  65 }
  66
  67 // lint is disabled for primitives because in this case `take`
  68 // has no clear benefit over `replace` and sometimes is harder to read
  69 fn dont_lint_primitive() {
  70     let mut pbool = true;
  71     let _ = std::mem::replace(&mut pbool, false);
  72
  73     let mut pint = 5;
  74     let _ = std::mem::replace(&mut pint, 0);
  75 }
  76
  77 fn main() {
  78     replace_option_with_none();
  79     replace_with_default();
  80     dont_lint_primitive();
  81 }
  82
  83 fn msrv_1_39() {
  84     #![clippy::msrv = "1.39"]
  85
  86     let mut s = String::from("foo");
  87     let _ = std::mem::replace(&mut s, String::default());
  88 }
  89
  90 fn msrv_1_40() {
  91     #![clippy::msrv = "1.40"]
  92
  93     let mut s = String::from("foo");
  94     let _ = std::mem::replace(&mut s, String::default());
  95 }