From 12c66926118cded6c1a7abd4cbeb9b3fbf31971e Mon Sep 17 00:00:00 2001
From: Hendiadyoin1 <leon.a@serenityos.org>
Date: Sat, 23 Sep 2023 13:47:16 +0200
Subject: [PATCH] LibJS: Defer GC during cell construction

This stops us from trying to collect not fully constructed Cells,
which's vtables are not fully initialized, which would cause issues
during GC.
---
 Userland/Libraries/LibJS/Heap/Heap.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Userland/Libraries/LibJS/Heap/Heap.h b/Userland/Libraries/LibJS/Heap/Heap.h
index 1a97a1e7d4..77880c9b7a 100644
--- a/Userland/Libraries/LibJS/Heap/Heap.h
+++ b/Userland/Libraries/LibJS/Heap/Heap.h
@@ -39,7 +39,9 @@ public:
     NonnullGCPtr<T> allocate_without_realm(Args&&... args)
     {
         auto* memory = allocate_cell(sizeof(T));
+        defer_gc();
         new (memory) T(forward<Args>(args)...);
+        undefer_gc();
         return *static_cast<T*>(memory);
     }
 
@@ -47,7 +49,9 @@ public:
     NonnullGCPtr<T> allocate(Realm& realm, Args&&... args)
     {
         auto* memory = allocate_cell(sizeof(T));
+        defer_gc();
         new (memory) T(forward<Args>(args)...);
+        undefer_gc();
         auto* cell = static_cast<T*>(memory);
         memory->initialize(realm);
         return *cell;