rspec/rules/S7432/rust/rule.adoc
github-actions[bot] 6edd31ee99
Create rule S7432: Reversed ranges and slices should not be empty (#4773)
* Create rule S7432

* Update RSPEC

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Co-authored-by: yassin-kammoun-sonarsource <yassin-kammoun-sonarsource@users.noreply.github.com>
Co-authored-by: yassin-kammoun-sonarsource <yassin.kammoun@sonarsource.com>
2025-03-19 13:06:47 +00:00

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== Why is this an issue?
Empty ranges result in no iterations, making any loop a no-op. Trying to index slices using reversed ranges will result in runtime panics. Both scenarios lead to bugs or logical errors in the code.
=== Code examples
==== Noncompliant code example
[source,rust,diff-id=1,diff-type=noncompliant]
----
fn main() {
(10..=0).for_each(|x| println!("{}", x)); // Noncompliant: Empty range
let arr = [1, 2, 3, 4, 5];
let sub = &arr[3..1]; // Noncompliant: Reversed slice indexing
}
----
==== Compliant solution
[source,rust,diff-id=1,diff-type=compliant]
----
fn main() {
(0..=10).rev().for_each(|x| println!("{}", x)); // Compliant: Properly reversed range for iteration
let arr = [1, 2, 3, 4, 5];
let sub = &arr[1..3]; // Compliant: Valid slice indexing
}
----
== Resources
=== Documentation
* Clippy Lints - https://rust-lang.github.io/rust-clippy/master/index.html#reversed_empty_ranges