375 lines
8.4 KiB
Rust
375 lines
8.4 KiB
Rust
// run-rustfix
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#![warn(clippy::while_let_on_iterator)]
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#![allow(clippy::never_loop, unreachable_code, unused_mut, dead_code)]
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fn base() {
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let mut iter = 1..20;
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for x in iter {
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println!("{}", x);
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}
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let mut iter = 1..20;
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for x in iter {
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println!("{}", x);
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}
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let mut iter = 1..20;
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for _ in iter {}
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let mut iter = 1..20;
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while let None = iter.next() {} // this is fine (if nonsensical)
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let mut iter = 1..20;
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if let Some(x) = iter.next() {
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// also fine
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println!("{}", x)
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}
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// the following shouldn't warn because it can't be written with a for loop
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let mut iter = 1u32..20;
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while let Some(_) = iter.next() {
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println!("next: {:?}", iter.next())
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}
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// neither can this
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let mut iter = 1u32..20;
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while let Some(_) = iter.next() {
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println!("next: {:?}", iter.next());
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}
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// or this
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let mut iter = 1u32..20;
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while let Some(_) = iter.next() {
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iter = 1..20;
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}
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}
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// Issue #1188
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fn refutable() {
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let a = [42, 1337];
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let mut b = a.iter();
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// consume all the 42s
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while let Some(&42) = b.next() {}
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let a = [(1, 2, 3)];
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let mut b = a.iter();
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while let Some(&(1, 2, 3)) = b.next() {}
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let a = [Some(42)];
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let mut b = a.iter();
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while let Some(&None) = b.next() {}
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/* This gives “refutable pattern in `for` loop binding: `&_` not covered”
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for &42 in b {}
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for &(1, 2, 3) in b {}
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for &Option::None in b.next() {}
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// */
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}
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fn refutable2() {
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// Issue 3780
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{
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let v = vec![1, 2, 3];
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let mut it = v.windows(2);
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while let Some([x, y]) = it.next() {
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println!("x: {}", x);
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println!("y: {}", y);
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}
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let mut it = v.windows(2);
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while let Some([x, ..]) = it.next() {
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println!("x: {}", x);
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}
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let mut it = v.windows(2);
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while let Some([.., y]) = it.next() {
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println!("y: {}", y);
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}
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let mut it = v.windows(2);
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for [..] in it {}
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let v = vec![[1], [2], [3]];
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let mut it = v.iter();
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while let Some([1]) = it.next() {}
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let mut it = v.iter();
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for [_x] in it {}
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}
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// binding
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{
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let v = vec![1, 2, 3];
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let mut it = v.iter();
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while let Some(x @ 1) = it.next() {
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println!("{}", x);
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}
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let v = vec![[1], [2], [3]];
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let mut it = v.iter();
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for x @ [_] in it {
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println!("{:?}", x);
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}
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}
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// false negative
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{
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let v = vec![1, 2, 3];
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let mut it = v.iter().map(Some);
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while let Some(Some(_) | None) = it.next() {
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println!("1");
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}
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}
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}
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fn nested_loops() {
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let a = [42, 1337];
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loop {
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let mut y = a.iter();
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for _ in y {
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// use a for loop here
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}
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}
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}
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fn issue1121() {
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use std::collections::HashSet;
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let mut values = HashSet::new();
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values.insert(1);
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while let Some(&value) = values.iter().next() {
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values.remove(&value);
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}
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}
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fn issue2965() {
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// This should not cause an ICE
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use std::collections::HashSet;
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let mut values = HashSet::new();
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values.insert(1);
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while let Some(..) = values.iter().next() {}
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}
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fn issue3670() {
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let array = [Some(0), None, Some(1)];
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let mut iter = array.iter();
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while let Some(elem) = iter.next() {
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let _ = elem.or_else(|| *iter.next()?);
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}
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}
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fn issue1654() {
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// should not lint if the iterator is generated on every iteration
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use std::collections::HashSet;
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let mut values = HashSet::new();
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values.insert(1);
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while let Some(..) = values.iter().next() {
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values.remove(&1);
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}
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while let Some(..) = values.iter().map(|x| x + 1).next() {}
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let chars = "Hello, World!".char_indices();
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while let Some((i, ch)) = chars.clone().next() {
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println!("{}: {}", i, ch);
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}
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}
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fn issue6491() {
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// Used in outer loop, needs &mut
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let mut it = 1..40;
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while let Some(n) = it.next() {
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for m in &mut it {
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if m % 10 == 0 {
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break;
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}
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println!("doing something with m: {}", m);
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}
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println!("n still is {}", n);
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}
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// This is fine, inner loop uses a new iterator.
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let mut it = 1..40;
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for n in it {
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let mut it = 1..40;
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for m in it {
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if m % 10 == 0 {
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break;
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}
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println!("doing something with m: {}", m);
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}
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// Weird binding shouldn't change anything.
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let (mut it, _) = (1..40, 0);
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for m in it {
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if m % 10 == 0 {
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break;
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}
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println!("doing something with m: {}", m);
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}
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// Used after the loop, needs &mut.
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let mut it = 1..40;
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for m in &mut it {
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if m % 10 == 0 {
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break;
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}
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println!("doing something with m: {}", m);
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}
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println!("next item {}", it.next().unwrap());
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println!("n still is {}", n);
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}
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}
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fn issue6231() {
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// Closure in the outer loop, needs &mut
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let mut it = 1..40;
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let mut opt = Some(0);
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while let Some(n) = opt.take().or_else(|| it.next()) {
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for m in &mut it {
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if n % 10 == 0 {
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break;
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}
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println!("doing something with m: {}", m);
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}
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println!("n still is {}", n);
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}
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}
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fn issue1924() {
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struct S<T>(T);
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impl<T: Iterator<Item = u32>> S<T> {
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fn f(&mut self) -> Option<u32> {
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// Used as a field.
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for i in &mut self.0 {
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if !(3..=7).contains(&i) {
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return Some(i);
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}
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}
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None
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}
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fn f2(&mut self) -> Option<u32> {
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// Don't lint, self borrowed inside the loop
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while let Some(i) = self.0.next() {
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if i == 1 {
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return self.f();
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}
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}
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None
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}
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}
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impl<T: Iterator<Item = u32>> S<(S<T>, Option<u32>)> {
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fn f3(&mut self) -> Option<u32> {
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// Don't lint, self borrowed inside the loop
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while let Some(i) = self.0.0.0.next() {
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if i == 1 {
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return self.0.0.f();
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}
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}
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while let Some(i) = self.0.0.0.next() {
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if i == 1 {
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return self.f3();
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}
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}
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// This one is fine, a different field is borrowed
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for i in &mut self.0.0.0 {
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if i == 1 {
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return self.0.1.take();
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} else {
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self.0.1 = Some(i);
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}
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}
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None
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}
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}
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struct S2<T>(T, u32);
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impl<T: Iterator<Item = u32>> Iterator for S2<T> {
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type Item = u32;
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fn next(&mut self) -> Option<u32> {
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self.0.next()
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}
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}
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// Don't lint, field of the iterator is accessed in the loop
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let mut it = S2(1..40, 0);
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while let Some(n) = it.next() {
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if n == it.1 {
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break;
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}
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}
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// Needs &mut, field of the iterator is accessed after the loop
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let mut it = S2(1..40, 0);
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for n in &mut it {
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if n == 0 {
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break;
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}
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}
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println!("iterator field {}", it.1);
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}
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fn issue7249() {
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let mut it = 0..10;
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let mut x = || {
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// Needs &mut, the closure can be called multiple times
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for x in &mut it {
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if x % 2 == 0 {
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break;
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}
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}
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};
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x();
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x();
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}
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fn issue7510() {
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let mut it = 0..10;
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let it = &mut it;
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// Needs to reborrow `it` as the binding isn't mutable
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for x in &mut *it {
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if x % 2 == 0 {
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break;
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}
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}
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println!("{}", it.next().unwrap());
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struct S<T>(T);
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let mut it = 0..10;
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let it = S(&mut it);
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// Needs to reborrow `it.0` as the binding isn't mutable
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for x in &mut *it.0 {
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if x % 2 == 0 {
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break;
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}
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}
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println!("{}", it.0.next().unwrap());
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}
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fn exact_match_with_single_field() {
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struct S<T>(T);
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let mut s = S(0..10);
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// Don't lint. `s.0` is used inside the loop.
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while let Some(_) = s.0.next() {
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let _ = &mut s.0;
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}
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}
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fn main() {
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let mut it = 0..20;
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for _ in it {
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println!("test");
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}
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}
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