From 9d1003028cfb1ca382b3ff87bafe8ec9c0235007 Mon Sep 17 00:00:00 2001
From: Svyatoslav Zaytsev <sviatsv@ya.ru>
Date: Sun, 23 Oct 2022 22:19:24 +0300
Subject: [PATCH] fix(eslint-plugin): isTypeReadonly stack overflow (#4476)

---
 .../prefer-readonly-parameter-types.test.ts    | 18 ++++++++++++++++++
 packages/type-utils/src/isTypeReadonly.ts      |  4 ++++
 .../type-utils/tests/isTypeReadonly.test.ts    | 14 ++++++++++++++
 3 files changed, 36 insertions(+)

diff --git a/packages/eslint-plugin/tests/rules/prefer-readonly-parameter-types.test.ts b/packages/eslint-plugin/tests/rules/prefer-readonly-parameter-types.test.ts
index 219b8cbdb08..b6b499b0efd 100644
--- a/packages/eslint-plugin/tests/rules/prefer-readonly-parameter-types.test.ts
+++ b/packages/eslint-plugin/tests/rules/prefer-readonly-parameter-types.test.ts
@@ -5,6 +5,7 @@ import type {
   InferMessageIdsTypeFromRule,
   InferOptionsTypeFromRule,
 } from '../../src/util';
+import { readonlynessOptionsDefaults } from '../../src/util';
 import { getFixturesRootDir, noFormat, RuleTester } from '../RuleTester';
 
 type MessageIds = InferMessageIdsTypeFromRule<typeof rule>;
@@ -362,6 +363,23 @@ ruleTester.run('prefer-readonly-parameter-types', rule, {
         },
       ],
     },
+    {
+      name: 'circular readonly types (Bug: #4476)',
+      code: `
+        interface Obj {
+          readonly [K: string]: Obj;
+        }
+        
+        function foo(event: Obj): void {}
+      `,
+      options: [
+        {
+          checkParameterProperties: true,
+          ignoreInferredTypes: false,
+          ...readonlynessOptionsDefaults,
+        },
+      ],
+    },
   ],
   invalid: [
     // arrays
diff --git a/packages/type-utils/src/isTypeReadonly.ts b/packages/type-utils/src/isTypeReadonly.ts
index 42dcc2ce907..cac7690ea3a 100644
--- a/packages/type-utils/src/isTypeReadonly.ts
+++ b/packages/type-utils/src/isTypeReadonly.ts
@@ -113,6 +113,10 @@ function isTypeReadonlyObject(
         return Readonlyness.Mutable;
       }
 
+      if (indexInfo.type === type) {
+        return Readonlyness.Readonly;
+      }
+
       return isTypeReadonlyRecurser(
         checker,
         indexInfo.type,
diff --git a/packages/type-utils/tests/isTypeReadonly.test.ts b/packages/type-utils/tests/isTypeReadonly.test.ts
index 60d822b57a1..77d9f65b2f9 100644
--- a/packages/type-utils/tests/isTypeReadonly.test.ts
+++ b/packages/type-utils/tests/isTypeReadonly.test.ts
@@ -134,6 +134,13 @@ describe('isTypeReadonly', () => {
           );
         });
 
+        describe('is readonly circular', () => {
+          const runTests = runTestIsReadonly;
+
+          it('handles circular readonly PropertySignature inside a readonly IndexSignature', () =>
+            runTests('interface Test { readonly [key: string]: Test };'));
+        });
+
         describe('is not readonly', () => {
           const runTests = runTestIsNotReadonly;
 
@@ -145,6 +152,13 @@ describe('isTypeReadonly', () => {
             runTests,
           );
         });
+
+        describe('is not readonly circular', () => {
+          const runTests = runTestIsNotReadonly;
+
+          it('handles circular mutable PropertySignature inside a readonly IndexSignature', () =>
+            runTests('interface Test { [key: string]: Test };'));
+        });
       });
 
       describe('Union', () => {