rust-lang / rust-lang/rust-clippy
needless_range_loop suggestion improvement
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Description
I encountered one suggestion from Clippy in context of needless_range_loop for a code as below
for idx in idx1..=idx2 {
// some stuff with Vec<int> type individual
}
it currently suggests using
for <item> in individual.iter_mut().take(idx2 + 1).skip(idx1)
This is all good and works but in my opinion the iterator can take far lesser values than it's taking now. Am not sure if it has any performance impact which I think it should have given it's taking more values into consideration.
take(n) yields elements until n elements are yielded or the end of the iterator is reached
Based on the above doc I assume that yielding idx2+1 will take more time/memory than `idx2+1-idx1
I recommend using below as suggestion
for <item> in individual.iter_mut().skip(idx1).take(idx2 - idx1 + 1)
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by locating the implementation and tests for the needless_range_loop lint in rust-clippy, then compare the two iterator suggestions in the issue. Verify the intended range semantics and whether the proposed ordering changes behavior or performance, and update the lint's expected suggestion and tests if appropriate.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100