Fix ruby segment fault (#3708)

* Fix ruby segment fault

1) rb_ary_new cannot be called during allocate function. During allocate
fucntion, the containing object hasn't been marked and rb_ary_new may
invoke gc to collect containing object.
2) The global map should be marked before allocating it. Otherwise it
may be garbage collected.

* Add test

* Remove commented code

* Fix grammer error

1 files changed, 1 insertions, 4 deletions

diff --git a/ruby/ext/google/protobuf_c/protobuf.h b/ruby/ext/google/protobuf_c/protobuf.h
index f4b110fe..21c7f001 100644
--- a/ruby/ext/google/protobuf_c/protobuf.h
+++ b/ruby/ext/google/protobuf_c/protobuf.h
@@ -116,10 +116,6 @@ struct Descriptor {
   const upb_handlers* pb_serialize_handlers;
   const upb_handlers* json_serialize_handlers;
   const upb_handlers* json_serialize_handlers_preserve;
-  // Handlers hold type class references for sub-message fields directly in some
-  // cases. We need to keep these rooted because they might otherwise be
-  // collected.
-  VALUE typeclass_references;
 };
 
 struct FieldDescriptor {
@@ -280,6 +276,7 @@ void Builder_free(void* _self);
 VALUE Builder_alloc(VALUE klass);
 void Builder_register(VALUE module);
 Builder* ruby_to_Builder(VALUE value);
+VALUE Builder_initialize(VALUE _self);
 VALUE Builder_add_message(VALUE _self, VALUE name);
 VALUE Builder_add_enum(VALUE _self, VALUE name);
 VALUE Builder_finalize_to_pool(VALUE _self, VALUE pool_rb);