From 7ca6365322007fd39175dae249e40cadabd432ea Mon Sep 17 00:00:00 2001
From: James Garbutt <43081j@users.noreply.github.com>
Date: Fri, 3 Jan 2025 14:34:58 +0000
Subject: [PATCH] chore(eslint-plugin): [no-for-in-array] use
 `getConstraintInfo`

Uses `getConstraintInfo` for determining if the right hand side of the
`for..in` is constrained or not.
---
 packages/eslint-plugin/src/rules/no-for-in-array.ts  | 12 ++++++++----
 .../tests/rules/no-for-in-array.test.ts              |  7 +++++++
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/packages/eslint-plugin/src/rules/no-for-in-array.ts b/packages/eslint-plugin/src/rules/no-for-in-array.ts
index ec8ebe9125fb..26c6a839456f 100644
--- a/packages/eslint-plugin/src/rules/no-for-in-array.ts
+++ b/packages/eslint-plugin/src/rules/no-for-in-array.ts
@@ -2,7 +2,7 @@ import * as ts from 'typescript';
 
 import {
   createRule,
-  getConstrainedTypeAtLocation,
+  getConstraintInfo,
   getParserServices,
   isTypeArrayTypeOrUnionOfArrayTypes,
 } from '../util';
@@ -30,11 +30,15 @@ export default createRule({
         const services = getParserServices(context);
         const checker = services.program.getTypeChecker();
 
-        const type = getConstrainedTypeAtLocation(services, node.right);
+        const { constraintType } = getConstraintInfo(
+          checker,
+          services.getTypeAtLocation(node.right),
+        );
 
         if (
-          isTypeArrayTypeOrUnionOfArrayTypes(type, checker) ||
-          (type.flags & ts.TypeFlags.StringLike) !== 0
+          constraintType != null &&
+          (isTypeArrayTypeOrUnionOfArrayTypes(constraintType, checker) ||
+            (constraintType.flags & ts.TypeFlags.StringLike) !== 0)
         ) {
           context.report({
             loc: getForStatementHeadLoc(context.sourceCode, node),
diff --git a/packages/eslint-plugin/tests/rules/no-for-in-array.test.ts b/packages/eslint-plugin/tests/rules/no-for-in-array.test.ts
index 47b3d1ab3ea2..78c1a6c0439a 100644
--- a/packages/eslint-plugin/tests/rules/no-for-in-array.test.ts
+++ b/packages/eslint-plugin/tests/rules/no-for-in-array.test.ts
@@ -23,6 +23,13 @@ for (const x of [3, 4, 5]) {
     `
 for (const x in { a: 1, b: 2, c: 3 }) {
   console.log(x);
+}
+    `,
+    `
+function f<T>(input: T) {
+  for (const x in input) {
+    console.log(x);
+  }
 }
     `,
   ],