From 185b7e92a37548255fcc8c5ab08b72abeadaf74e Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Fri, 8 Dec 2023 15:18:07 -0500
Subject: [PATCH] Make WeakKeyMap safe for compaction during allocation

During allocation, the table may not have been allocated yet which would
crash in the st_foreach.
---
 test/ruby/test_weakkeymap.rb | 4 ++++
 weakmap.c                    | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/test/ruby/test_weakkeymap.rb b/test/ruby/test_weakkeymap.rb
index be3e80cec46932..799cee2d75b85b 100644
--- a/test/ruby/test_weakkeymap.rb
+++ b/test/ruby/test_weakkeymap.rb
@@ -123,6 +123,10 @@ def test_compaction
     end;
   end
 
+  def test_gc_compact_stress
+    EnvUtil.under_gc_compact_stress { ObjectSpace::WeakKeyMap.new }
+  end
+
   private
 
   def assert_weak_include(m, k, n = 100)
diff --git a/weakmap.c b/weakmap.c
index 4e568e676bcc97..641e530f58a334 100644
--- a/weakmap.c
+++ b/weakmap.c
@@ -609,7 +609,9 @@ wkmap_compact(void *ptr)
 {
     struct weakkeymap *w = ptr;
 
-    st_foreach_with_replace(w->table, wkmap_compact_table_i, wkmap_compact_table_replace, (st_data_t)0);
+    if (w->table) {
+        st_foreach_with_replace(w->table, wkmap_compact_table_i, wkmap_compact_table_replace, (st_data_t)0);
+    }
 }
 
 static const rb_data_type_t weakkeymap_type = {