refactor delete rb_method_entry_copy

The deleted function was to destructively overwrite existing method
entries, which is now considered to be a bad idea.  Delete it, and
assign a newly created method entry instead.

class.c

@@ -956,25 +956,48 @@ include_modules_at(const VALUE klass, VALUE c, VALUE module, int search_super)
     return method_changed;
 }
 
+typedef struct tuple {
+    struct RClass *klass;
+    struct RClass *origin;
+} tuple;
+
+static enum rb_id_table_iterator_result
+inject_refined_method(ID *key, VALUE *value, void *data, int _)
+{
+    const tuple             *ptr     = data;
+    const rb_method_entry_t *me      = *(rb_method_entry_t **) value;
+    const rb_method_entry_t *orig_me = me->def->body.refined.orig_me;
+    rb_method_entry_t       *new_me  =
+        rb_method_entry_create(
+            me->called_id,
+            me->owner,
+            me->defined_class,
+            rb_method_definition_create(
+                me->def->type,
+                me->def->original_id,
+                &(rb_method_refined_t) {
+                    .orig_me = NULL,
+                    .owner   = me->def->body.refined.owner, }));
+    METHOD_ENTRY_FLAGS_COPY(new_me, me);
+    rb_id_table_insert(RCLASS_M_TBL(ptr->klass), *key, (VALUE)new_me);
+    RB_OBJ_WRITTEN(ptr->klass, Qundef, new_me);
+    *value = (VALUE)rb_method_entry_clone(orig_me);
+    RB_OBJ_WRITTEN(ptr->origin, Qundef, orig_me);
+    return ID_TABLE_CONTINUE;
+}
+
 static enum rb_id_table_iterator_result
 move_refined_method(ID key, VALUE value, void *data)
 {
+    const tuple       *ptr = data;
     rb_method_entry_t *me = (rb_method_entry_t *) value;
-    VALUE klass = (VALUE)data;
-    struct rb_id_table *tbl = RCLASS_M_TBL(klass);
 
     if (me->def->type == VM_METHOD_TYPE_REFINED) {
 	if (me->def->body.refined.orig_me) {
-	    const rb_method_entry_t *orig_me = me->def->body.refined.orig_me, *new_me;
-	    RB_OBJ_WRITE(me, &me->def->body.refined.orig_me, NULL);
-	    new_me = rb_method_entry_clone(me);
-	    rb_id_table_insert(tbl, key, (VALUE)new_me);
-	    RB_OBJ_WRITTEN(klass, Qundef, new_me);
-	    rb_method_entry_copy(me, orig_me);
-	    return ID_TABLE_CONTINUE;
+            return ID_TABLE_REPLACE;
 	}
 	else {
-	    rb_id_table_insert(tbl, key, (VALUE)me);
+            rb_id_table_insert(RCLASS_M_TBL(ptr->klass), key, (VALUE)me);
 	    return ID_TABLE_DELETE;
 	}
     }
@@ -1000,7 +1023,12 @@ rb_prepend_module(VALUE klass, VALUE module)
 	RCLASS_SET_ORIGIN(klass, origin);
 	RCLASS_M_TBL(origin) = RCLASS_M_TBL(klass);
 	RCLASS_M_TBL_INIT(klass);
-	rb_id_table_foreach(RCLASS_M_TBL(origin), move_refined_method, (void *)klass);
+        rb_id_table_foreach_with_replace_with_key(
+            RCLASS_M_TBL(origin),
+            move_refined_method,
+            inject_refined_method,
+            &(tuple) { RCLASS(klass), RCLASS(origin), },
+            true);
     }
     changed = include_modules_at(klass, klass, module, FALSE);
     if (changed < 0)

method.h

@@ -185,6 +185,8 @@ STATIC_ASSERT(sizeof_method_def, offsetof(rb_method_definition_t, body)==8);
     ((def)->type == VM_METHOD_TYPE_REFINED && \
      UNDEFINED_METHOD_ENTRY_P((def)->body.refined.orig_me))
 
+const rb_method_definition_t *rb_method_definition_create(rb_method_type_t which, ID what, const void *how);
+
 void rb_add_method_cfunc(VALUE klass, ID mid, VALUE (*func)(ANYARGS), int argc, rb_method_visibility_t visi);
 void rb_add_method_iseq(VALUE klass, ID mid, const rb_iseq_t *iseq, rb_cref_t *cref, rb_method_visibility_t visi);
 void rb_add_refined_method_entry(VALUE refined_class, ID mid);
@@ -221,7 +223,6 @@ void rb_sweep_method_entry(void *vm);
 
 const rb_method_entry_t *rb_method_entry_clone(const rb_method_entry_t *me);
 const rb_callable_method_entry_t *rb_method_entry_complement_defined_class(const rb_method_entry_t *src_me, ID called_id, VALUE defined_class);
-void rb_method_entry_copy(rb_method_entry_t *dst, const rb_method_entry_t *src);
 
 void rb_scope_visibility_set(rb_method_visibility_t);
 

proc.c

@@ -15,8 +15,6 @@
 #include "vm_core.h"
 #include "iseq.h"
 
-extern const rb_method_definition_t *rb_method_definition_create(rb_method_type_t type, ID mid, const void *opts);
-
 /* Proc.new with no block will raise an exception in the future
  * versions */
 #define PROC_NEW_REQUIRES_BLOCK 0

vm_insnhelper.c

@@ -19,7 +19,6 @@
 #include "ruby/config.h"
 #include "debug_counter.h"
 
-extern const rb_method_definition_t *rb_method_definition_create(rb_method_type_t type, ID mid, const void *opts);
 extern void rb_method_entry_spoof(const rb_method_entry_t *me);
 extern int rb_method_definition_eq(const rb_method_definition_t *d1, const rb_method_definition_t *d2);
 extern VALUE rb_make_no_method_exception(VALUE exc, VALUE format, VALUE obj,

vm_method.c

@@ -546,17 +546,6 @@ rb_method_entry_complement_defined_class(const rb_method_entry_t *src_me, ID cal
     return (rb_callable_method_entry_t *)me;
 }
 
-void
-rb_method_entry_copy(rb_method_entry_t *dst, const rb_method_entry_t *src)
-{
-    *(rb_method_definition_t **)&dst->def = method_definition_addref(src->def);
-    method_definition_reset(dst);
-    dst->called_id = src->called_id;
-    RB_OBJ_WRITE((VALUE)dst, &dst->owner, src->owner);
-    RB_OBJ_WRITE((VALUE)dst, &dst->defined_class, src->defined_class);
-    METHOD_ENTRY_FLAGS_COPY(dst, src);
-}
-
 static rb_method_entry_t*
 make_method_entry_refined(VALUE owner, rb_method_entry_t *me)
 {