Fixes#11759

PR Checklist

• Addresses an existing open issue:fixesBug: [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 inContributing were taken

Overview

This PR fixes an issue where therestrict-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 theallow 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' }]}classBase{}classDerivedextendsBase{}constbar=newDerived();`${bar}`;// Error: Invalid type "Derived"

Solution

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

1. Added hasBaseTypes() helper function to identify types with base types (Interface or Class)
2. Added isAllowedTypeOrBase() function that recursively checks if a type or its base types match the allow list
3. Included cycle detection using a Set to prevent infinite recursion
4. 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