fix(eslint-plugin): [no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters #10602

ronami · 2025-01-03T14:40:53Z

PR Checklist

Addresses an existing open issue: fixes Bug: [no-unnecessary-condition] False positive on dynamic access of generic value #10600
That issue was marked as accepting prs
Steps in Contributing were taken

Overview

This PR resolves #10600 and removes some duplicated logic for checking special-case types in a union (any, unknown, or types with the TypeVariable type flag).

The current implementation seems to pick up unconstrained type parameters by checking the presence of the TypeVariable type flag. I think this is necessary (over getConstraintInfo) as the check needs to detect types such as the following:

function test<T>(arg: T, key: keyof T) {
  if (arg[key]) {
    //
  }
}

typescript-eslint · 2025-01-03T14:40:55Z

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nx-cloud · 2025-01-03T14:41:44Z

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codecov · 2025-01-03T15:09:37Z

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.90%. Comparing base (d63ea3b) to head (d603a5e).
Report is 20 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10602   +/-   ##
=======================================
  Coverage   86.90%   86.90%           
=======================================
  Files         446      446           
  Lines       15505    15506    +1     
  Branches     4517     4517           
=======================================
+ Hits        13475    13476    +1     
  Misses       1675     1675           
  Partials      355      355

Flag	Coverage Δ
unittest	`86.90% <100.00%> (+<0.01%)`	⬆️

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	`99.24% <100.00%> (+<0.01%)`	⬆️

JoshuaKGoldberg

JoshuaKGoldberg · 2025-01-07T13:36:06Z

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

-              isTypeUnknownType(part) ||
-              isTypeFlagSet(part, ts.TypeFlags.TypeVariable),
-          )
-      ) {


[Praise] Heh, yeah, this was getting a little hard to read inline even before...

@yeonjuan

##### [v8.20.0](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8200-2025-01-13) ##### 🚀 Features - **eslint-plugin:** \[consistent-type-assertions] add arrayLiteralTypeAssertions options ([#10565](typescript-eslint/typescript-eslint#10565)) - **eslint-plugin:** \[no-deprecated] add allow options ([#10585](typescript-eslint/typescript-eslint#10585)) - **eslint-plugin:** \[no-misused-spread] add new rule ([#10551](typescript-eslint/typescript-eslint#10551)) ##### 🩹 Fixes - **eslint-plugin:** \[no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters ([#10602](typescript-eslint/typescript-eslint#10602)) - **eslint-plugin:** \[no-shadow] ignore ordering of type declarations ([#10593](typescript-eslint/typescript-eslint#10593)) ##### ❤️ Thank You - Josh Goldberg ✨ - Ronen Amiel - YeonJuan [@yeonjuan](https://github.com/yeonjuan) You can read about our [versioning strategy](https://main--typescript-eslint.netlify.app/users/versioning) and [releases](https://main--typescript-eslint.netlify.app/users/releases) on our website.

@yeonjuan

##### [v8.20.0](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8200-2025-01-13) ##### 🚀 Features - **eslint-plugin:** \[consistent-type-assertions] add arrayLiteralTypeAssertions options ([#10565](typescript-eslint/typescript-eslint#10565)) - **eslint-plugin:** \[no-deprecated] add allow options ([#10585](typescript-eslint/typescript-eslint#10585)) - **eslint-plugin:** \[no-misused-spread] add new rule ([#10551](typescript-eslint/typescript-eslint#10551)) ##### 🩹 Fixes - **eslint-plugin:** \[no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters ([#10602](typescript-eslint/typescript-eslint#10602)) - **eslint-plugin:** \[no-shadow] ignore ordering of type declarations ([#10593](typescript-eslint/typescript-eslint#10593)) ##### ❤️ Thank You - Josh Goldberg ✨ - Ronen Amiel - YeonJuan [@yeonjuan](https://github.com/yeonjuan) You can read about our [versioning strategy](https://main--typescript-eslint.netlify.app/users/versioning) and [releases](https://main--typescript-eslint.netlify.app/users/releases) on our website.

@yeonjuan

##### [v8.20.0](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8200-2025-01-13) ##### 🚀 Features - **eslint-plugin:** \[consistent-type-assertions] add arrayLiteralTypeAssertions options ([#10565](typescript-eslint/typescript-eslint#10565)) - **eslint-plugin:** \[no-deprecated] add allow options ([#10585](typescript-eslint/typescript-eslint#10585)) - **eslint-plugin:** \[no-misused-spread] add new rule ([#10551](typescript-eslint/typescript-eslint#10551)) ##### 🩹 Fixes - **eslint-plugin:** \[no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters ([#10602](typescript-eslint/typescript-eslint#10602)) - **eslint-plugin:** \[no-shadow] ignore ordering of type declarations ([#10593](typescript-eslint/typescript-eslint#10593)) ##### ❤️ Thank You - Josh Goldberg ✨ - Ronen Amiel - YeonJuan [@yeonjuan](https://github.com/yeonjuan) You can read about our [versioning strategy](https://main--typescript-eslint.netlify.app/users/versioning) and [releases](https://main--typescript-eslint.netlify.app/users/releases) on our website.

@yeonjuan

##### [v8.20.0](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8200-2025-01-13) ##### 🚀 Features - **eslint-plugin:** \[consistent-type-assertions] add arrayLiteralTypeAssertions options ([#10565](typescript-eslint/typescript-eslint#10565)) - **eslint-plugin:** \[no-deprecated] add allow options ([#10585](typescript-eslint/typescript-eslint#10585)) - **eslint-plugin:** \[no-misused-spread] add new rule ([#10551](typescript-eslint/typescript-eslint#10551)) ##### 🩹 Fixes - **eslint-plugin:** \[no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters ([#10602](typescript-eslint/typescript-eslint#10602)) - **eslint-plugin:** \[no-shadow] ignore ordering of type declarations ([#10593](typescript-eslint/typescript-eslint#10593)) ##### ❤️ Thank You - Josh Goldberg ✨ - Ronen Amiel - YeonJuan [@yeonjuan](https://github.com/yeonjuan) You can read about our [versioning strategy](https://main--typescript-eslint.netlify.app/users/versioning) and [releases](https://main--typescript-eslint.netlify.app/users/releases) on our website.

@yeonjuan

| datasource | package | from | to | | ---------- | -------------------------------- | ------ | ------ | | npm | @typescript-eslint/eslint-plugin | 8.19.1 | 8.20.0 | | npm | @typescript-eslint/parser | 8.19.1 | 8.20.0 | ## [v8.20.0](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8200-2025-01-13) ##### 🚀 Features - **eslint-plugin:** \[consistent-type-assertions] add arrayLiteralTypeAssertions options ([#10565](typescript-eslint/typescript-eslint#10565)) - **eslint-plugin:** \[no-deprecated] add allow options ([#10585](typescript-eslint/typescript-eslint#10585)) - **eslint-plugin:** \[no-misused-spread] add new rule ([#10551](typescript-eslint/typescript-eslint#10551)) ##### 🩹 Fixes - **eslint-plugin:** \[no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters ([#10602](typescript-eslint/typescript-eslint#10602)) - **eslint-plugin:** \[no-shadow] ignore ordering of type declarations ([#10593](typescript-eslint/typescript-eslint#10593)) ##### ❤️ Thank You - Josh Goldberg ✨ - Ronen Amiel - YeonJuan [@yeonjuan](https://github.com/yeonjuan) You can read about our [versioning strategy](https://main--typescript-eslint.netlify.app/users/versioning) and [releases](https://main--typescript-eslint.netlify.app/users/releases) on our website.

@yeonjuan

| datasource | package | from | to | | ---------- | -------------------------------- | ------ | ------ | | npm | @typescript-eslint/eslint-plugin | 8.19.1 | 8.20.0 | | npm | @typescript-eslint/parser | 8.19.1 | 8.20.0 | ## [v8.20.0](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8200-2025-01-13) ##### 🚀 Features - **eslint-plugin:** \[consistent-type-assertions] add arrayLiteralTypeAssertions options ([#10565](typescript-eslint/typescript-eslint#10565)) - **eslint-plugin:** \[no-deprecated] add allow options ([#10585](typescript-eslint/typescript-eslint#10585)) - **eslint-plugin:** \[no-misused-spread] add new rule ([#10551](typescript-eslint/typescript-eslint#10551)) ##### 🩹 Fixes - **eslint-plugin:** \[no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters ([#10602](typescript-eslint/typescript-eslint#10602)) - **eslint-plugin:** \[no-shadow] ignore ordering of type declarations ([#10593](typescript-eslint/typescript-eslint#10593)) ##### ❤️ Thank You - Josh Goldberg ✨ - Ronen Amiel - YeonJuan [@yeonjuan](https://github.com/yeonjuan) You can read about our [versioning strategy](https://main--typescript-eslint.netlify.app/users/versioning) and [releases](https://main--typescript-eslint.netlify.app/users/releases) on our website.

don't flag optional chaining for unconstrained type parameters

d603a5e

ronami marked this pull request as ready for review January 3, 2025 15:11

kirkwaiblinger mentioned this pull request Jan 3, 2025

Repo: add testing around TypeVariables/IndexedAccessTypes and getConstraintInfo #10606

Open

JoshuaKGoldberg approved these changes Jan 7, 2025

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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 Jan 7, 2025

JoshuaKGoldberg merged commit d6e5978 into typescript-eslint:main Jan 13, 2025
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ronami deleted the no-unnecessary-condition-dont-flag-unconstrained-type-parameter branch January 13, 2025 20:45

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fix(eslint-plugin): [no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters #10602

fix(eslint-plugin): [no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters #10602

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JoshuaKGoldberg Jan 7, 2025

fix(eslint-plugin): [no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters #10602

fix(eslint-plugin): [no-unnecessary-condition] don't flag optional chaining for union types with an unconstrained type parameters #10602

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