From 2c997a097449f129b6e36107ec3ce1979c6c117e Mon Sep 17 00:00:00 2001
From: Charlie Savage <cfis@savagexi.com>
Date: Sat, 6 Jan 2024 21:51:14 -0800
Subject: [PATCH] Define rb_class_attached_object for older versions of Ruby.

---
 ext/ruby_prof/rp_method.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/ext/ruby_prof/rp_method.c b/ext/ruby_prof/rp_method.c
index 7464c764..261d59d9 100644
--- a/ext/ruby_prof/rp_method.c
+++ b/ext/ruby_prof/rp_method.c
@@ -6,6 +6,16 @@
 #include "rp_method.h"
 #include "rp_profile.h"
 
+#include <ruby/version.h>
+
+// Needed for Ruby 3.0.* and 3.1.*
+#if RUBY_API_VERSION_MAJOR == 3 && RUBY_API_VERSION_MINOR < 2
+   VALUE rb_class_attached_object(VALUE klass)
+   {
+     return rb_iv_get(klass, "__attached__");
+   }
+#endif
+
 VALUE cRpMethodInfo;
 
 /* ================  Helper Functions  =================*/