From 2b3dc11c9ac034650a20180b6c3523edf4982a11 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Fri, 1 Nov 2024 15:49:58 +0100
Subject: [PATCH] Properly declare global variables (#941)

Fix: https://github.com/ruby/json/issues/672

GC compaction might move these objects around so the global
C variable MUST be declared to the GC so it's updated there too.
---
 ext/oj/mimic_json.c | 6 +++++-
 ext/oj/rails.c      | 2 ++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/ext/oj/mimic_json.c b/ext/oj/mimic_json.c
index cef9d506..aad4c622 100644
--- a/ext/oj/mimic_json.c
+++ b/ext/oj/mimic_json.c
@@ -837,11 +837,15 @@ void oj_mimic_json_methods(VALUE json) {
     } else {
         json_error = rb_define_class_under(json, "JSONError", rb_eStandardError);
     }
+
+    rb_global_variable(&oj_json_parser_error_class);
     if (rb_const_defined_at(json, rb_intern("ParserError"))) {
         oj_json_parser_error_class = rb_const_get(json, rb_intern("ParserError"));
     } else {
         oj_json_parser_error_class = rb_define_class_under(json, "ParserError", json_error);
     }
+
+    rb_global_variable(&oj_json_generator_error_class);
     if (rb_const_defined_at(json, rb_intern("GeneratorError"))) {
         oj_json_generator_error_class = rb_const_get(json, rb_intern("GeneratorError"));
     } else {
@@ -867,8 +871,8 @@ void oj_mimic_json_methods(VALUE json) {
         rb_require("oj/state");
     }
     // Pull in the JSON::State mimic file.
+    rb_global_variable(&state_class);
     state_class = rb_const_get_at(generator, rb_intern("State"));
-    rb_gc_register_mark_object(state_class);
 }
 
 /* Document-module: JSON
diff --git a/ext/oj/rails.c b/ext/oj/rails.c
index 91fed0db..fe63b471 100644
--- a/ext/oj/rails.c
+++ b/ext/oj/rails.c
@@ -1101,6 +1101,8 @@ static VALUE rails_set_decoder(VALUE self) {
     } else {
         json_error = rb_define_class_under(json, "JSONError", rb_eStandardError);
     }
+
+    rb_global_variable(&oj_json_parser_error_class);
     if (rb_const_defined_at(json, rb_intern("ParserError"))) {
         oj_json_parser_error_class = rb_const_get(json, rb_intern("ParserError"));
     } else {