Output parent object info when marking T_NONE

2 files changed, 10 insertions, 2 deletions

diff --git a/gc/default/default.c b/gc/default/default.c
index b7d43b0acb..aa06b7cc06 100644
--- a/gc/default/default.c
+++ b/gc/default/default.c
@@ -4395,7 +4395,15 @@ gc_mark_check_t_none(rb_objspace_t *objspace, VALUE obj)
         char obj_info_buf[256];
         rb_raw_obj_info(obj_info_buf, 256, obj);
 
-        rb_bug("try to mark T_NONE object (obj: %s)", obj_info_buf);
+        char parent_obj_info_buf[256];
+        if (objspace->rgengc.parent_object == Qfalse) {
+            strcpy(parent_obj_info_buf, "(none)");
+        }
+        else {
+            rb_raw_obj_info(parent_obj_info_buf, 256, objspace->rgengc.parent_object);
+        }
+
+        rb_bug("try to mark T_NONE object (obj: %s, parent: %s)", obj_info_buf, parent_obj_info_buf);
     }
 }
 
diff --git a/gc/gc.h b/gc/gc.h
index fe9aaeb965..8ca9987477 100644
--- a/gc/gc.h
+++ b/gc/gc.h
@@ -58,7 +58,7 @@ RUBY_SYMBOL_EXPORT_BEGIN
 // files in Ruby.
 size_t rb_size_mul_or_raise(size_t x, size_t y, VALUE exc);
 void rb_objspace_reachable_objects_from(VALUE obj, void (func)(VALUE, void *), void *data);
-void rb_obj_info_dump(VALUE obj);
+const char *rb_raw_obj_info(char *const buff, const size_t buff_size, VALUE obj);
 const char *rb_obj_info(VALUE obj);
 size_t rb_obj_memsize_of(VALUE obj);
 bool ruby_free_at_exit_p(void);