Prevent rb_define_(class|module) classes from moving

Before this commit, classes and modules would be registered with the
VM's `defined_module_hash`.  The key was the ID of the class, but that
meant that it was possible for hash collisions to occur.  The compactor
doesn't allow classes in the `defined_module_hash` to move, but if there
is a conflict, then it's possible a class would be removed from the hash
and not get pined.

This commit changes the key / value of the hash just to be the class
itself, thus preventing movement.

1 files changed, 3 insertions, 0 deletions

diff --git a/class.c b/class.c
index d0ff92b6eb..0cee5caae2 100644
--- a/class.c
+++ b/class.c
@@ -659,6 +659,9 @@ rb_define_class(const char *name, VALUE super)
 	if (rb_class_real(RCLASS_SUPER(klass)) != super) {
 	    rb_raise(rb_eTypeError, "superclass mismatch for class %s", name);
 	}
+
+        /* Class may have been defined in Ruby and not pin-rooted */
+        rb_vm_add_root_module(id, klass);
 	return klass;
     }
     if (!super) {