From 4de049a3f9709ab8b0b192c40e83b910b80d6de3 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Wed, 23 Apr 2025 11:42:26 +0200
Subject: [PATCH] Deprecate `ObjectSpace._id2ref`

[Feature #15408]

Matz decided to deprecate it for Ruby 2.6 or 2.7 but that never
actually happened.

Given the object_id table is a contention point for Ractors
it seems sensible to finally deprecate this API so we can
generate and store object ids more efficiently in the future.
---
 gc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gc.c b/gc.c
index 953b2ed70d..0ca08d53e0 100644
--- a/gc.c
+++ b/gc.c
@@ -1965,6 +1965,8 @@ rb_gc_obj_free_vm_weak_references(VALUE obj)
  *
  *  On multi-ractor mode, if the object is not shareable, it raises
  *  RangeError.
+ *
+ *  This method is deprecated and should no longer be used.
  */
 
 static VALUE
@@ -2012,6 +2014,7 @@ id2ref(VALUE objid)
 static VALUE
 os_id2ref(VALUE os, VALUE objid)
 {
+    rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "ObjectSpace._id2ref is deprecated");
     return id2ref(objid);
 }