84f89f30eb
Updates `needless_collect` to lint for collecting into a method or function argument thats taking an `IntoIterator` (for example `extend`). Every `Iterator` trivially implements `IntoIterator` and colleting it only causes an unnecessary allocation.
78 lines
2.8 KiB
Rust
78 lines
2.8 KiB
Rust
//@run-rustfix
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#![allow(unused, clippy::suspicious_map, clippy::iter_count)]
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use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList};
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#[warn(clippy::needless_collect)]
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#[allow(unused_variables, clippy::iter_cloned_collect, clippy::iter_next_slice)]
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fn main() {
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let sample = [1; 5];
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let len = sample.iter().collect::<Vec<_>>().len();
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if sample.iter().collect::<Vec<_>>().is_empty() {
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// Empty
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}
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sample.iter().cloned().collect::<Vec<_>>().contains(&1);
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// #7164 HashMap's and BTreeMap's `len` usage should not be linted
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sample.iter().map(|x| (x, x)).collect::<HashMap<_, _>>().len();
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sample.iter().map(|x| (x, x)).collect::<BTreeMap<_, _>>().len();
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sample.iter().map(|x| (x, x)).collect::<HashMap<_, _>>().is_empty();
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sample.iter().map(|x| (x, x)).collect::<BTreeMap<_, _>>().is_empty();
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// Notice the `HashSet`--this should not be linted
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sample.iter().collect::<HashSet<_>>().len();
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// Neither should this
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sample.iter().collect::<BTreeSet<_>>().len();
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sample.iter().collect::<LinkedList<_>>().len();
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sample.iter().collect::<LinkedList<_>>().is_empty();
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sample.iter().cloned().collect::<LinkedList<_>>().contains(&1);
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sample.iter().collect::<LinkedList<_>>().contains(&&1);
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// `BinaryHeap` doesn't have `contains` method
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sample.iter().collect::<BinaryHeap<_>>().len();
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sample.iter().collect::<BinaryHeap<_>>().is_empty();
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// Don't lint string from str
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let _ = ["", ""].into_iter().collect::<String>().is_empty();
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let _ = sample.iter().collect::<HashSet<_>>().is_empty();
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let _ = sample.iter().collect::<HashSet<_>>().contains(&&0);
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struct VecWrapper<T>(Vec<T>);
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impl<T> core::ops::Deref for VecWrapper<T> {
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type Target = Vec<T>;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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impl<T> IntoIterator for VecWrapper<T> {
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type IntoIter = <Vec<T> as IntoIterator>::IntoIter;
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type Item = <Vec<T> as IntoIterator>::Item;
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fn into_iter(self) -> Self::IntoIter {
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self.0.into_iter()
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}
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}
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impl<T> FromIterator<T> for VecWrapper<T> {
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fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
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Self(Vec::from_iter(iter))
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}
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}
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let _ = sample.iter().collect::<VecWrapper<_>>().is_empty();
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let _ = sample.iter().collect::<VecWrapper<_>>().contains(&&0);
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#[allow(clippy::double_parens)]
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{
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Vec::<u8>::new().extend((0..10).collect::<Vec<_>>());
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foo((0..10).collect::<Vec<_>>());
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bar((0..10).collect::<Vec<_>>(), (0..10).collect::<Vec<_>>());
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baz((0..10), (), ('a'..='z').collect::<Vec<_>>())
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}
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}
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fn foo(_: impl IntoIterator<Item = usize>) {}
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fn bar<I: IntoIterator<Item = usize>>(_: Vec<usize>, _: I) {}
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fn baz<I: IntoIterator<Item = usize>>(_: I, _: (), _: impl IntoIterator<Item = char>) {}
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