acc3842d43
This lint checks for code that looks like
```rust
let something : Vec<_> = (0..100).map(|_| {
1 + 2 + 3
}).collect();
```
which is more clear as
```rust
let something : Vec<_> = std::iter::repeat_with(|| {
1 + 2 + 3
}).take(100).collect();
```
or
```rust
let something : Vec<_> =
std::iter::repeat_n(1 + 2 + 3, 100)
.collect();
```
That is, a map over a range which does nothing with the parameter
passed to it is simply a function (or closure) being called `n`
times and could be more semantically expressed using `take`.
74 lines
2.4 KiB
Rust
74 lines
2.4 KiB
Rust
#![allow(
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unused,
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clippy::redundant_closure,
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clippy::reversed_empty_ranges,
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clippy::identity_op
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)]
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#![warn(clippy::map_with_unused_argument_over_ranges)]
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fn do_something() -> usize {
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todo!()
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}
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fn do_something_interesting(x: usize, y: usize) -> usize {
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todo!()
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}
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macro_rules! gen {
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() => {
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(0..10).map(|_| do_something());
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};
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}
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fn main() {
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// These should be raised
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std::iter::repeat_with(|| do_something()).take(10);
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std::iter::repeat_with(|| do_something()).take(10);
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std::iter::repeat_with(|| do_something()).take(11);
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std::iter::repeat_with(|| do_something()).take(7);
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std::iter::repeat_with(|| do_something()).take(8);
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std::iter::repeat_n(3, 10);
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std::iter::repeat_with(|| {
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let x = 3;
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x + 2
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}).take(10);
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std::iter::repeat_with(|| do_something()).take(10).collect::<Vec<_>>();
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let upper = 4;
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std::iter::repeat_with(|| do_something()).take(upper);
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let upper_fn = || 4;
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std::iter::repeat_with(|| do_something()).take(upper_fn());
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std::iter::repeat_with(|| do_something()).take(upper_fn() + 1);
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std::iter::repeat_with(|| do_something()).take(upper_fn() - 2);
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std::iter::repeat_with(|| do_something()).take(upper_fn() - 1);
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(-3..9).map(|_| do_something());
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std::iter::repeat_with(|| do_something()).take(0);
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std::iter::repeat_with(|| do_something()).take(1);
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std::iter::repeat_with(|| do_something()).take((1 << 4) - 0);
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// These should not be raised
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gen!();
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let lower = 2;
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let lower_fn = || 2;
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(lower..upper_fn()).map(|_| do_something()); // Ranges not starting at zero not yet handled
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(lower_fn()..upper_fn()).map(|_| do_something()); // Ranges not starting at zero not yet handled
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(lower_fn()..=upper_fn()).map(|_| do_something()); // Ranges not starting at zero not yet handled
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(0..10).map(|x| do_something_interesting(x, 4)); // Actual map over range
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"Foobar".chars().map(|_| do_something()); // Not a map over range
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// i128::MAX == 340282366920938463463374607431768211455
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(0..=340282366920938463463374607431768211455).map(|_: u128| do_something()); // Can't be replaced due to overflow
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}
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#[clippy::msrv = "1.27"]
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fn msrv_1_27() {
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(0..10).map(|_| do_something());
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}
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#[clippy::msrv = "1.28"]
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fn msrv_1_28() {
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std::iter::repeat_with(|| do_something()).take(10);
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}
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#[clippy::msrv = "1.81"]
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fn msrv_1_82() {
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std::iter::repeat(3).take(10);
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}
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