Rule Request: Use .first instead of [0]
Open
Nobody has claimed this yet.
rule-request
- Dominant language
- Swift
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Description
Rule Request
- Why should this rule be added? Share links to existing discussion about what
the community thinks about this.
Indexing a collection using [0] is unsafe and could cause a crash if the collection is empty
- Provide several examples of what would and wouldn't trigger violations.
Bad
let value = array[0]
let something = resource.collection[0].group.value
Good
let value = array.first
let something = resource.collection.first.group.value
- Should the rule be configurable, if so what parameters should be configurable?
No
- Should the rule be opt-in or enabled by default? Why?
I think this rule should be enabled by default for the index-at-zero case. If the rule is expanded beyond that, I think it should be opt-in.
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
The issue names no files, tests, or entry points. Start by locating SwiftLint’s existing rule implementations and rule tests, then compare how similar rules are specified. Done means the rule flags the shown [0] cases, accepts the shown .first cases, and follows the requested default behavior.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- swift
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100