Don't preserve object_id when moving object to another Ractor

That seemed like the logical thing to do to me, but ko1 disagree.

Author: byroot

bootstraptest/test_ractor.rb

@@ -2101,13 +2101,3 @@ def ==(o)
     :fail
   end
 }
-
-# moved objects keep their object_id
-assert_equal 'ok', %q{
-  ractor = Ractor.new { Ractor.receive }
-  obj = Object.new
-  id = obj.object_id
-  ractor.send(obj, move: true)
-  roundtripped_obj = ractor.take
-  roundtripped_obj.object_id == id ? :ok : :fail
-}

gc.c

@@ -665,7 +665,6 @@ typedef struct gc_function_map {
     // Object ID
     VALUE (*object_id)(void *objspace_ptr, VALUE obj);
     VALUE (*object_id_to_ref)(void *objspace_ptr, VALUE object_id);
-    void (*object_id_move)(void *objspace_ptr, VALUE dest, VALUE src);
     // Forking
     void (*before_fork)(void *objspace_ptr);
     void (*after_fork)(void *objspace_ptr, rb_pid_t pid);
@@ -843,7 +842,6 @@ ruby_modular_gc_init(void)
     // Object ID
     load_modular_gc_func(object_id);
     load_modular_gc_func(object_id_to_ref);
-    load_modular_gc_func(object_id_move);
     // Forking
     load_modular_gc_func(before_fork);
     load_modular_gc_func(after_fork);
@@ -927,7 +925,6 @@ ruby_modular_gc_init(void)
 // Object ID
 # define rb_gc_impl_object_id rb_gc_functions.object_id
 # define rb_gc_impl_object_id_to_ref rb_gc_functions.object_id_to_ref
-# define rb_gc_impl_object_id_move rb_gc_functions.object_id_move
 // Forking
 # define rb_gc_impl_before_fork rb_gc_functions.before_fork
 # define rb_gc_impl_after_fork rb_gc_functions.after_fork
@@ -2664,12 +2661,7 @@ rb_gc_mark_roots(void *objspace, const char **categoryp)
 void
 rb_gc_ractor_moved(VALUE dest, VALUE src)
 {
-    void *objspace = rb_gc_get_objspace();
-    if (UNLIKELY(FL_TEST_RAW(src, FL_SEEN_OBJ_ID))) {
-        rb_gc_impl_object_id_move(objspace, dest, src);
-    }
-
-    rb_gc_obj_free(objspace, src);
+    rb_gc_obj_free(rb_gc_get_objspace(), src);
     MEMZERO((void *)src, char, rb_gc_obj_slot_size(src));
     RBASIC(src)->flags = T_OBJECT | FL_FREEZE; // Avoid mutations using bind_call, etc.
 }

gc/default/default.c

@@ -1614,27 +1614,6 @@ rb_gc_impl_object_id_to_ref(void *objspace_ptr, VALUE object_id)
     }
 }
 
-void
-rb_gc_impl_object_id_move(void *objspace_ptr, VALUE dest, VALUE src)
-{
-   /* If the source object's object_id has been seen, we need to update
-    * the object to object id mapping. */
-   st_data_t id = 0;
-   rb_objspace_t *objspace = objspace_ptr;
-
-   unsigned int lev = rb_gc_vm_lock();
-   st_data_t key = (st_data_t)src;
-   if (!st_delete(objspace->obj_to_id_tbl, &key, &id)) {
-       rb_bug("gc_move: object ID seen, but not in mapping table: %s", rb_obj_info(src));
-   }
-   FL_UNSET_RAW(src, FL_SEEN_OBJ_ID);
-
-   st_insert(objspace->obj_to_id_tbl, (st_data_t)dest, id);
-   st_insert(objspace->id_to_obj_tbl, id, (st_data_t)dest);
-   FL_SET_RAW(dest, FL_SEEN_OBJ_ID);
-   rb_gc_vm_unlock(lev);
-}
-
 static void free_stack_chunks(mark_stack_t *);
 static void mark_stack_free_cache(mark_stack_t *);
 static void heap_page_free(rb_objspace_t *objspace, struct heap_page *page);

gc/gc_impl.h

@@ -103,7 +103,6 @@ GC_IMPL_FN void rb_gc_impl_shutdown_call_finalizer(void *objspace_ptr);
 // Object ID
 GC_IMPL_FN VALUE rb_gc_impl_object_id(void *objspace_ptr, VALUE obj);
 GC_IMPL_FN VALUE rb_gc_impl_object_id_to_ref(void *objspace_ptr, VALUE object_id);
-GC_IMPL_FN void rb_gc_impl_object_id_move(void *objspace_ptr, VALUE dest, VALUE src);
 // Forking
 GC_IMPL_FN void rb_gc_impl_before_fork(void *objspace_ptr);
 GC_IMPL_FN void rb_gc_impl_after_fork(void *objspace_ptr, rb_pid_t pid);

gc/mmtk/mmtk.c

@@ -1155,27 +1155,6 @@ rb_gc_impl_object_id_to_ref(void *objspace_ptr, VALUE object_id)
     }
 }
 
-void
-rb_gc_impl_object_id_move(void *objspace_ptr, VALUE dest, VALUE src)
-{
-   /* If the source object's object_id has been seen, we need to update
-    * the object to object id mapping. */
-   st_data_t id = 0;
-   struct objspace *objspace = objspace_ptr;
-
-   unsigned int lev = rb_gc_vm_lock();
-   st_data_t key = (st_data_t)src;
-   if (!st_delete(objspace->obj_to_id_tbl, &key, &id)) {
-       rb_bug("gc_move: object ID seen, but not in mapping table: %s", rb_obj_info(src));
-   }
-   FL_UNSET_RAW(src, FL_SEEN_OBJ_ID);
-
-   st_insert(objspace->obj_to_id_tbl, (st_data_t)dest, id);
-   st_insert(objspace->id_to_obj_tbl, id, (st_data_t)dest);
-   FL_SET_RAW(dest, FL_SEEN_OBJ_ID);
-   rb_gc_vm_unlock(lev);
-}
-
 // Forking
 
 void