From e831ad2ffc6e3b644e06ede79fccb1b3a67d98a5 Mon Sep 17 00:00:00 2001
From: karl-police <karl-police2001@bluewin.ch>
Date: Fri, 13 Sep 2024 14:48:31 +0200
Subject: [PATCH] Make index wait for pending indexerTy

---
 Analysis/src/TypeFunction.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Analysis/src/TypeFunction.cpp b/Analysis/src/TypeFunction.cpp
index 205d0fc46..529d9a062 100644
--- a/Analysis/src/TypeFunction.cpp
+++ b/Analysis/src/TypeFunction.cpp
@@ -2206,6 +2206,19 @@ TypeFunctionReductionResult<TypeId> indexFunctionImpl(
         return {std::nullopt, true, {}, {}};
 
     TypeId indexerTy = follow(typeParams.at(1));
+
+    // Whether the type is still pending.
+    // 
+    // TODO: A generalized sanity check function for all type functions?
+    // But it should be optional for customization
+    // for functions that specifically need type function
+    // This here fixes a stack overflow.
+    // https://github.com/luau-lang/luau/issues/1406
+    if (isPending(indexerTy, ctx->solver))
+    {
+        return {std::nullopt, false, {indexerTy}, {}};
+    }
+
     std::shared_ptr<const NormalizedType> indexerNormTy = ctx->normalizer->normalize(indexerTy);
 
     // if the indexer failed to normalize, we can't reduce, but know nothing about inhabitance.