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

   1 // run-rustfix
   2
   3 #![warn(clippy::from_iter_instead_of_collect)]
   4 #![allow(unused_imports)]
   5
   6 use std::collections::{BTreeMap, BTreeSet, HashMap, VecDeque};
   7 use std::iter::FromIterator;
   8
   9 struct Foo(Vec<bool>);
  10
  11 impl FromIterator<bool> for Foo {
  12     fn from_iter<T: IntoIterator<Item = bool>>(_: T) -> Self {
  13         todo!()
  14     }
  15 }
  16
  17 impl<'a> FromIterator<&'a bool> for Foo {
  18     fn from_iter<T: IntoIterator<Item = &'a bool>>(iter: T) -> Self {
  19         <Self as FromIterator<bool>>::from_iter(iter.into_iter().copied())
  20     }
  21 }
  22
  23 fn main() {
  24     let iter_expr = std::iter::repeat(5).take(5);
  25     let _ = Vec::from_iter(iter_expr);
  26
  27     let _ = HashMap::<usize, &i8>::from_iter(vec![5, 5, 5, 5].iter().enumerate());
  28
  29     Vec::from_iter(vec![42u32]);
  30
  31     let a = vec![0, 1, 2];
  32     assert_eq!(a, Vec::from_iter(0..3));
  33     assert_eq!(a, Vec::<i32>::from_iter(0..3));
  34
  35     let mut b = VecDeque::from_iter(0..3);
  36     b.push_back(4);
  37
  38     let mut b = VecDeque::<i32>::from_iter(0..3);
  39     b.push_back(4);
  40
  41     {
  42         use std::collections;
  43         let mut b = collections::VecDeque::<i32>::from_iter(0..3);
  44         b.push_back(4);
  45     }
  46
  47     let values = [(0, 'a'), (1, 'b'), (2, 'c'), (3, 'd')];
  48     let bm = BTreeMap::from_iter(values.iter().cloned());
  49     let mut bar = BTreeMap::from_iter(bm.range(0..2));
  50     bar.insert(&4, &'e');
  51
  52     let mut bts = BTreeSet::from_iter(0..3);
  53     bts.insert(2);
  54     {
  55         use std::collections;
  56         let _ = collections::BTreeSet::from_iter(0..3);
  57         let _ = collections::BTreeSet::<u32>::from_iter(0..3);
  58     }
  59
  60     for _i in Vec::from_iter([1, 2, 3].iter()) {}
  61     for _i in Vec::<&i32>::from_iter([1, 2, 3].iter()) {}
  62 }