fix(eslint-plugin): [restrict-template-expressions] check base types in allow list #11764

Higangssh · 2025-11-16T15:56:57Z

PR Checklist

Addresses an existing open issue: fixes Bug: [restrict-template-expressions] should check if superclass is ignored #11759
That issue was marked as [accepting prs](https://github.com/typescript-eslint/typescript-eslint/issues?q=is%
3Aopen+is%3Aissue+label%3A%22accepting+prs%22)
Steps in Contributing were taken

Overview

This PR fixes an issue where the restrict-template-expressions rule incorrectly rejects derived class instances
in template literals when their base class is in the allow list.

Problem

Currently, when a base class is included in the allow option, derived classes extending it are still flagged as
errors, violating the Liskov Substitution Principle where subtypes should be substitutable for their supertypes.

Example:

// Configuration: { allow: [{ from: 'file', name: 'Base' }] }
class Base { }
class Derived extends Base { }
const bar = new Derived();
`${bar}`;  // Error: Invalid type "Derived"

Solution

Implemented recursive base type checking following the pattern established in the no-base-to-string rule:

Added hasBaseTypes() helper function to identify types with base types (Interface or Class)
Added isAllowedTypeOrBase() function that recursively checks if a type or its base types match the allow list
Included cycle detection using a Set to prevent infinite recursion
Updated recursivelyCheckType() to utilize the new base type checking mechanism

Changes

packages/eslint-plugin/src/rules/restrict-template-expressions.ts: Added base type checking logic
packages/eslint-plugin/tests/rules/restrict-template-expressions.test.ts: Added test case for inheritance
scenario

Allow derived types in template expressions when base types are in allow list Fixes typescript-eslint#11759

typescript-eslint · 2025-11-16T15:57:02Z

Thanks for the PR, @Higangssh!

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 · 2025-11-16T15:58:28Z

View your CI Pipeline Execution ↗ for commit 80be898

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☁️ Nx Cloud last updated this comment at 2025-11-28 18:12:06 UTC

codecov · 2025-11-16T16:08:48Z

Codecov Report

❌ Patch coverage is 93.10345% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.48%. Comparing base (16cf0f7) to head (80be898).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/eslint-plugin/src/util/baseTypeUtils.ts	90.90%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11764      +/-   ##
==========================================
- Coverage   90.49%   90.48%   -0.01%     
==========================================
  Files         522      523       +1     
  Lines       53367    53393      +26     
  Branches     8918     8919       +1     
==========================================
+ Hits        48293    48315      +22     
- Misses       5059     5063       +4     
  Partials       15       15

Flag	Coverage Δ
unittest	`90.48% <93.10%> (-0.01%)`	⬇️

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

Files with missing lines	Coverage Δ
...kages/eslint-plugin/src/rules/no-base-to-string.ts	`99.01% <100.00%> (-0.07%)`	⬇️
...-plugin/src/rules/restrict-template-expressions.ts	`100.00% <100.00%> (ø)`
packages/eslint-plugin/src/util/baseTypeUtils.ts	`90.90% <90.90%> (ø)`

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
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JoshuaKGoldberg

Looks good! ✨

Just a few cleanup/refactor requests, nothing on the core logic. Thanks for getting this started!

packages/eslint-plugin/tests/rules/restrict-template-expressions.test.ts

packages/eslint-plugin/src/rules/restrict-template-expressions.ts

…te-expressions-base-types

- Remove unnecessary test comments - Extract hasBaseTypes to shared util - Create matchesTypeOrBaseType with matcher pattern

Higangssh · 2025-11-18T13:14:21Z

Thanks for the review! I've addressed all the feedback:

Removed unnecessary test comments
Extracted hasBaseTypes to shared util
Created matchesTypeOrBaseType with matcher pattern

JoshuaKGoldberg · 2025-11-18T13:58:18Z

packages/eslint-plugin/tests/rules/restrict-template-expressions.test.ts

[Testing] Oh, sory, I just realized - this is missing test coverage for extending multiple classes.

A extends B, C where B is listed

A extends B, C where C is listed

A extends B, C + B extends D, E where E is listed

etc.

JoshuaKGoldberg

Sorry, a bit more testing please

Higangssh · 2025-11-18T14:14:38Z

@JoshuaKGoldberg Added tests for multiple interface inheritance. Thanks for the thorough review - really
appreciate you taking the time to guide me through this! Let me know if there's anything else that needs
adjusting

JoshuaKGoldberg

💯 thanks! Very thorough, nicely done.

@Higangssh

| datasource | package | from | to | | ---------- | -------------------------------- | ------ | ------ | | npm | @typescript-eslint/eslint-plugin | 8.48.0 | 8.48.1 | | npm | @typescript-eslint/parser | 8.48.0 | 8.48.1 | ## [v8.48.1](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8481-2025-12-02) ##### 🩹 Fixes - **eslint-plugin:** \[restrict-template-expressions] check base types in allow list ([#11764](typescript-eslint/typescript-eslint#11764), [#11759](typescript-eslint/typescript-eslint#11759)) - **eslint-plugin:** honor ignored base types on generic classes ([#11767](typescript-eslint/typescript-eslint#11767)) - **eslint-plugin:** \[consistent-type-exports] check value flag before resolving alias ([#11769](typescript-eslint/typescript-eslint#11769)) ##### ❤️ Thank You - Josh Goldberg - OleksandraKordonets - SangheeSon [@Higangssh](https://github.com/Higangssh) - tao You can read about our [versioning strategy](https://typescript-eslint.io/users/versioning) and [releases](https://typescript-eslint.io/users/releases) on our website.

@Higangssh

| datasource | package | from | to | | ---------- | -------------------------------- | ------ | ------ | | npm | @typescript-eslint/eslint-plugin | 8.48.0 | 8.48.1 | | npm | @typescript-eslint/parser | 8.48.0 | 8.48.1 | ## [v8.48.1](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8481-2025-12-02) ##### 🩹 Fixes - **eslint-plugin:** \[restrict-template-expressions] check base types in allow list ([#11764](typescript-eslint/typescript-eslint#11764), [#11759](typescript-eslint/typescript-eslint#11759)) - **eslint-plugin:** honor ignored base types on generic classes ([#11767](typescript-eslint/typescript-eslint#11767)) - **eslint-plugin:** \[consistent-type-exports] check value flag before resolving alias ([#11769](typescript-eslint/typescript-eslint#11769)) ##### ❤️ Thank You - Josh Goldberg - OleksandraKordonets - SangheeSon [@Higangssh](https://github.com/Higangssh) - tao You can read about our [versioning strategy](https://typescript-eslint.io/users/versioning) and [releases](https://typescript-eslint.io/users/releases) on our website.

This PR contains the following updates: | Package | Change | Age | Confidence | |---|---|---|---| | [@typescript-eslint/eslint-plugin](https://typescript-eslint.io/packages/eslint-plugin) ([source](https://github.com/typescript-eslint/typescript-eslint/tree/HEAD/packages/eslint-plugin)) | [`8.47.0` -> `8.48.1`](https://renovatebot.com/diffs/npm/@typescript-eslint%2feslint-plugin/8.47.0/8.48.1) | [![age](https://developer.mend.io/api/mc/badges/age/npm/@typescript-eslint%2feslint-plugin/8.48.1?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/@typescript-eslint%2feslint-plugin/8.47.0/8.48.1?slim=true)](https://docs.renovatebot.com/merge-confidence/) | | [@typescript-eslint/parser](https://typescript-eslint.io/packages/parser) ([source](https://github.com/typescript-eslint/typescript-eslint/tree/HEAD/packages/parser)) | [`8.47.0` -> `8.48.1`](https://renovatebot.com/diffs/npm/@typescript-eslint%2fparser/8.47.0/8.48.1) | [![age](https://developer.mend.io/api/mc/badges/age/npm/@typescript-eslint%2fparser/8.48.1?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/@typescript-eslint%2fparser/8.47.0/8.48.1?slim=true)](https://docs.renovatebot.com/merge-confidence/) | --- ### Release Notes <details> <summary>typescript-eslint/typescript-eslint (@typescript-eslint/eslint-plugin)</summary> ### [`v8.48.1`](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8481-2025-12-02) [Compare Source](typescript-eslint/typescript-eslint@v8.48.0...v8.48.1) ##### 🩹 Fixes - **eslint-plugin:** \[restrict-template-expressions] check base types in allow list ([#11764](typescript-eslint/typescript-eslint#11764), [#11759](typescript-eslint/typescript-eslint#11759)) - **eslint-plugin:** honor ignored base types on generic classes ([#11767](typescript-eslint/typescript-eslint#11767)) - **eslint-plugin:** \[consistent-type-exports] check value flag before resolving alias ([#11769](typescript-eslint/typescript-eslint#11769)) ##### ❤️ Thank You - Josh Goldberg - OleksandraKordonets - SangheeSon [@Higangssh](https://github.com/Higangssh) - tao You can read about our [versioning strategy](https://typescript-eslint.io/users/versioning) and [releases](https://typescript-eslint.io/users/releases) on our website. ### [`v8.48.0`](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8480-2025-11-24) [Compare Source](typescript-eslint/typescript-eslint@v8.47.0...v8.48.0) ##### 🚀 Features - **eslint-plugin:** \[no-redundant-type-constituents] use assignability checking for redundancy checks ([#10744](typescript-eslint/typescript-eslint#10744)) ##### 🩹 Fixes - **typescript-estree:** disallow binding patterns in parameter properties ([#11760](typescript-eslint/typescript-eslint#11760)) - **eslint-plugin:** \[consistent-generic-constructors] ignore when constructor is typed array ([#10477](typescript-eslint/typescript-eslint#10477)) ##### ❤️ Thank You - Dima Barabash [@dbarabashh](https://github.com/dbarabashh) - JamesHenry [@JamesHenry](https://github.com/JamesHenry) - Josh Goldberg - mdm317 [@gen-ip-1](https://github.com/gen-ip-1) You can read about our [versioning strategy](https://typescript-eslint.io/users/versioning) and [releases](https://typescript-eslint.io/users/releases) on our website. </details> <details> <summary>typescript-eslint/typescript-eslint (@typescript-eslint/parser)</summary> ### [`v8.48.1`](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/parser/CHANGELOG.md#8481-2025-12-02) [Compare Source](typescript-eslint/typescript-eslint@v8.48.0...v8.48.1) This was a version bump only for parser to align it with other projects, there were no code changes. 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@Higangssh

| datasource | package | from | to | | ---------- | -------------------------------- | ------ | ------ | | npm | @typescript-eslint/eslint-plugin | 8.48.0 | 8.48.1 | | npm | @typescript-eslint/parser | 8.48.0 | 8.48.1 | ## [v8.48.1](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8481-2025-12-02) ##### 🩹 Fixes - **eslint-plugin:** \[restrict-template-expressions] check base types in allow list ([#11764](typescript-eslint/typescript-eslint#11764), [#11759](typescript-eslint/typescript-eslint#11759)) - **eslint-plugin:** honor ignored base types on generic classes ([#11767](typescript-eslint/typescript-eslint#11767)) - **eslint-plugin:** \[consistent-type-exports] check value flag before resolving alias ([#11769](typescript-eslint/typescript-eslint#11769)) ##### ❤️ Thank You - Josh Goldberg - OleksandraKordonets - SangheeSon [@Higangssh](https://github.com/Higangssh) - tao You can read about our [versioning strategy](https://typescript-eslint.io/users/versioning) and [releases](https://typescript-eslint.io/users/releases) on our website.

@Higangssh

| datasource | package | from | to | | ---------- | -------------------------------- | ------ | ------ | | npm | @typescript-eslint/eslint-plugin | 8.48.0 | 8.48.1 | | npm | @typescript-eslint/parser | 8.48.0 | 8.48.1 | ## [v8.48.1](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8481-2025-12-02) ##### 🩹 Fixes - **eslint-plugin:** \[restrict-template-expressions] check base types in allow list ([#11764](typescript-eslint/typescript-eslint#11764), [#11759](typescript-eslint/typescript-eslint#11759)) - **eslint-plugin:** honor ignored base types on generic classes ([#11767](typescript-eslint/typescript-eslint#11767)) - **eslint-plugin:** \[consistent-type-exports] check value flag before resolving alias ([#11769](typescript-eslint/typescript-eslint#11769)) ##### ❤️ Thank You - Josh Goldberg - OleksandraKordonets - SangheeSon [@Higangssh](https://github.com/Higangssh) - tao You can read about our [versioning strategy](https://typescript-eslint.io/users/versioning) and [releases](https://typescript-eslint.io/users/releases) on our website.

@Higangssh

| datasource | package | from | to | | ---------- | -------------------------------- | ------ | ------ | | npm | @typescript-eslint/eslint-plugin | 8.48.0 | 8.48.1 | | npm | @typescript-eslint/parser | 8.48.0 | 8.48.1 | ## [v8.48.1](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/CHANGELOG.md#8481-2025-12-02) ##### 🩹 Fixes - **eslint-plugin:** \[restrict-template-expressions] check base types in allow list ([#11764](typescript-eslint/typescript-eslint#11764), [#11759](typescript-eslint/typescript-eslint#11759)) - **eslint-plugin:** honor ignored base types on generic classes ([#11767](typescript-eslint/typescript-eslint#11767)) - **eslint-plugin:** \[consistent-type-exports] check value flag before resolving alias ([#11769](typescript-eslint/typescript-eslint#11769)) ##### ❤️ Thank You - Josh Goldberg - OleksandraKordonets - SangheeSon [@Higangssh](https://github.com/Higangssh) - tao You can read about our [versioning strategy](https://typescript-eslint.io/users/versioning) and [releases](https://typescript-eslint.io/users/releases) on our website.

fix(restrict-template-expressions): check base types in allow list

dfca648

Allow derived types in template expressions when base types are in allow list Fixes typescript-eslint#11759

Higangssh mentioned this pull request Nov 16, 2025

Bug: [restrict-template-expressions] should check if superclass is ignored #11759

Closed

4 tasks

Higangssh changed the title ~~fix(restrict-template-expressions): check base types in allow list~~ fix(eslint-plugin): [restrict-template-expressions] check base types in allow list Nov 16, 2025

Higangssh added 3 commits November 17, 2025 01:30

fix: improve test coverage and fix import formatting

6ac61a0

fix: improve test coverage and fix linting issues

95ad776

chore: trigger CI rebuild

8eaddd5

JoshuaKGoldberg added the awaiting response Issues waiting for a reply from the OP or another party label Nov 17, 2025

JoshuaKGoldberg requested changes Nov 17, 2025

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Higangssh added 2 commits November 18, 2025 19:31

Merge remote-tracking branch 'upstream/main' into fix/restrict-templa…

e77fd7a

…te-expressions-base-types

refactor: deduplicate base type checking logic

c6b7ac8

- Remove unnecessary test comments - Extract hasBaseTypes to shared util - Create matchesTypeOrBaseType with matcher pattern

remove unnecessary test comments

29092d8

JoshuaKGoldberg self-requested a review November 18, 2025 13:57

github-actions bot removed the awaiting response Issues waiting for a reply from the OP or another party label Nov 18, 2025

JoshuaKGoldberg reviewed Nov 18, 2025

View reviewed changes

JoshuaKGoldberg requested changes Nov 18, 2025

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JoshuaKGoldberg added the awaiting response Issues waiting for a reply from the OP or another party label Nov 18, 2025

add multiple inheritance tests

90532b0

chore: retrigger CI

f89753c

Higangssh requested a review from JoshuaKGoldberg November 28, 2025 13:42

github-actions bot removed the awaiting response Issues waiting for a reply from the OP or another party label Nov 28, 2025

JoshuaKGoldberg previously approved these changes Nov 28, 2025

View reviewed changes

JoshuaKGoldberg dismissed their stale review via 80be898 November 28, 2025 18:01

Merge branch 'main'

80be898

JoshuaKGoldberg merged commit 906cc3c into typescript-eslint:main Nov 28, 2025
64 checks passed

chrisbbreuer mentioned this pull request Dec 2, 2025

chore(deps): update all non-major dependencies stacksjs/eslint-plugin#67

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fix(eslint-plugin): [restrict-template-expressions] check base types in allow list #11764

fix(eslint-plugin): [restrict-template-expressions] check base types in allow list #11764

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Higangssh commented Nov 16, 2025

PR Checklist

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