fix(eslint-plugin): [no-unnecessary-condition] don't report on unnecessary optional array index access when `noUncheckedIndexedAccess` is enabled #10961

ronami · 2025-03-16T18:17:49Z

PR Checklist

Addresses an existing open issue: fixes Bug: [no-unnecessary-condition] doesn't report on unnecessary optional array index access when noUncheckedIndexedAccess is enabled #10960
That issue was marked as accepting prs
Steps in Contributing were taken

Overview

This PR addresses #10960 and disables the special-casing of optional array index access when noUncheckedIndexedAccess is enabled.

This makes the rule report cases like the following:

declare const test: Array<{ a?: string }>;

// Reported by TypeScript as the object is possibly 'undefined'
test[0].a;

if (test[0]?.a) {
  // Optional chaining isn't necessary here
  test[0].a;    
}

if (test[0]?.a) {
  // Should be reported but doesn't?
  test[0]?.a;
}

Note that this also causes the rule to report on unnecessary optional index access that's deeper in the chain (only when noUncheckedIndexedAccess is turned on):

declare const arr2: Array<{ x: { y: { z: object } } }>;

// the following (previously wasn't reported):
arr2[42]?.x?.y?.z;

// is auto-fixed into:
arr2[42]?.x.y.z;

I've added a couple of tests to verify the rule handles these cases correctly when noUncheckedIndexedAccess is enabled.

typescript-eslint · 2025-03-16T18:17:52Z

Thanks for the PR, @ronami!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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nx-cloud · 2025-03-16T18:18:38Z

View your CI Pipeline Execution ↗ for commit e3a479c.

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☁️ Nx Cloud last updated this comment at 2025-03-24 11:52:57 UTC

codecov · 2025-03-16T18:33:16Z

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.97%. Comparing base (543d36c) to head (e3a479c).
Report is 13 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10961      +/-   ##
==========================================
+ Coverage   87.58%   87.97%   +0.38%     
==========================================
  Files         470      470              
  Lines       16095    16710     +615     
  Branches     4668     4711      +43     
==========================================
+ Hits        14097    14700     +603     
- Misses       1642     1664      +22     
+ Partials      356      346      -10

Flag	Coverage Δ
unittest	`87.97% <100.00%> (+0.38%)`	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...slint-plugin/src/rules/no-unnecessary-condition.ts	`99.21% <100.00%> (+<0.01%)`	⬆️

... and 15 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

JoshuaKGoldberg

Nice and clean! 🧹

packages/eslint-plugin/src/rules/no-unnecessary-condition.ts

kirkwaiblinger

This looks great!! I definitely like the behavior that the test cases demonstrate 🙂

initial implementation

06db97e

add tests

a03ba8e

ronami marked this pull request as ready for review March 16, 2025 18:53

JoshuaKGoldberg previously approved these changes Mar 17, 2025

View reviewed changes

JoshuaKGoldberg added the 1 approval >=1 team member has approved this PR; we're now leaving it open for more reviews before we merge label Mar 17, 2025

kirkwaiblinger reviewed Mar 18, 2025

View reviewed changes

packages/eslint-plugin/src/rules/no-unnecessary-condition.ts Show resolved Hide resolved

cover missing edge cases

e3a479c

ronami dismissed JoshuaKGoldberg’s stale review via e3a479c March 23, 2025 19:29

JoshuaKGoldberg removed the 1 approval >=1 team member has approved this PR; we're now leaving it open for more reviews before we merge label Mar 24, 2025

JoshuaKGoldberg requested a review from kirkwaiblinger March 24, 2025 11:51

kirkwaiblinger approved these changes Mar 24, 2025

View reviewed changes

JoshuaKGoldberg merged commit 3241e46 into typescript-eslint:main Mar 24, 2025
58 of 59 checks passed

ronami deleted the no-unnecessary-condition-no-unchecked-index-access branch March 24, 2025 20:32

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fix(eslint-plugin): [no-unnecessary-condition] don't report on unnecessary optional array index access when `noUncheckedIndexedAccess` is enabled #10961

fix(eslint-plugin): [no-unnecessary-condition] don't report on unnecessary optional array index access when `noUncheckedIndexedAccess` is enabled #10961

ronami commented Mar 16, 2025 •

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fix(eslint-plugin): [no-unnecessary-condition] don't report on unnecessary optional array index access when noUncheckedIndexedAccess is enabled #10961

fix(eslint-plugin): [no-unnecessary-condition] don't report on unnecessary optional array index access when noUncheckedIndexedAccess is enabled #10961

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ronami commented Mar 16, 2025 • edited Loading

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Overview

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fix(eslint-plugin): [no-unnecessary-condition] don't report on unnecessary optional array index access when `noUncheckedIndexedAccess` is enabled #10961

fix(eslint-plugin): [no-unnecessary-condition] don't report on unnecessary optional array index access when `noUncheckedIndexedAccess` is enabled #10961

ronami commented Mar 16, 2025 •

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netlify bot commented Mar 16, 2025 •

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nx-cloud bot commented Mar 16, 2025 •

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codecov bot commented Mar 16, 2025 •

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