From ff6fdf1b9b1bbfff63c304a803003cd007b2b2b1 Mon Sep 17 00:00:00 2001
From: JohnnyMorganz <johnnymorganz@outlook.com>
Date: Wed, 23 Nov 2022 19:00:16 +0000
Subject: [PATCH] Fix stack overflow on self-referential __index mtv

---
 CHANGELOG.md    | 4 ++++
 src/LuauExt.cpp | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2dfbcc8d..38584cca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed stack overflow when looking up properties on a table type where the `__index` is set to itself
+
 ## [1.14.0] - 2022-11-13
 
 ### Added
diff --git a/src/LuauExt.cpp b/src/LuauExt.cpp
index 245f7467..8fb40a19 100644
--- a/src/LuauExt.cpp
+++ b/src/LuauExt.cpp
@@ -687,7 +687,8 @@ std::optional<Luau::Property> lookupProp(const Luau::TypeId& parentType, const L
             if (indexIt != mtable->props.end())
             {
                 Luau::TypeId followed = Luau::follow(indexIt->second.type);
-                if (Luau::get<Luau::TableTypeVar>(followed) || Luau::get<Luau::MetatableTypeVar>(followed))
+                if ((Luau::get<Luau::TableTypeVar>(followed) || Luau::get<Luau::MetatableTypeVar>(followed)) &&
+                    followed != parentType) // ensure acyclic
                 {
                     return lookupProp(followed, name);
                 }