Method#super_method

static VALUE
method_super_method(VALUE method)
{
    const struct METHOD *data;
    VALUE super_class, iclass;
    ID mid;
    const rb_method_entry_t *me;

    TypedData_Get_Struct(method, struct METHOD, &method_data_type, data);
    iclass = data->iclass;
    if (!iclass) return Qnil;
    bool is_refinement_method = refinement_module_p(data->me->owner);
    if (data->me->def->type == VM_METHOD_TYPE_ALIAS && data->me->defined_class) {
        super_class = RCLASS_SUPER(rb_find_defined_class_by_owner(data->me->defined_class,
            data->me->def->body.alias.original_me->owner));
        mid = data->me->def->body.alias.original_me->def->original_id;
    }
    else if (is_refinement_method) {
        if (RICLASS_FOR_REFINEMENT_P(iclass)) {
            do {
                super_class = RCLASS_SUPER(iclass);
                iclass = super_class;
            } while (RICLASS_FOR_REFINEMENT_P(super_class));
        }
        else {
            super_class = find_refined_target_ancestor(iclass, rb_refinement_module_get_refined_class(data->me->owner));
            if (!super_class) {
                super_class = RCLASS_SUPER(data->me->owner);
            }
        }
        mid = data->me->def->original_id;
    }
    else {
        VALUE klass = iclass;
        if (RICLASS_FOR_REFINEMENT_P(klass)) {
            // Refined methods need this check before superclass determination
            klass = RBASIC(klass)->klass;
        }
        super_class = RCLASS_SUPER(RCLASS_ORIGIN(klass));
        mid = data->me->def->original_id;
    }
    if (!super_class) return Qnil;

    // For refined methods, skip refinements for the same definition, but consider
    // refinements for superclass methods
    const rb_method_definition_t *skip_def = is_refinement_method ? data->me->def : NULL;

    // Use the CREF of the Method/UnboundMethod, not the CREF of the caller of super_method.
    // We must avoid the use of rb_callable_method_entry_with_refinements, as that will
    // implicitly use the refinements activated in of the caller of super_method.
    const rb_cref_t *cref = NULL;
    switch (data->me->def->type) {
      case VM_METHOD_TYPE_ISEQ:
        cref = data->me->def->body.iseq.cref;
        break;
      case VM_METHOD_TYPE_BMETHOD: {
        const rb_proc_t *proc;
        GetProcPtr(data->me->def->body.bmethod.proc, proc);
        const struct rb_block *block = &proc->block;
        if (vm_block_type(block) == block_type_iseq)
            cref = rb_vm_get_cref(block->as.captured.ep);
        break;
      }
      default:
        break;
    }
    VALUE klass = super_class;
    me = NULL;
    while (klass) {
        const rb_callable_method_entry_t *cme = rb_callable_method_entry(klass, mid);
        if (!cme) break;
        if (cme->def->type != VM_METHOD_TYPE_REFINED) {
            me = (rb_method_entry_t *)cme;
            iclass = cme->defined_class;
            break;
        }
        // Look through all CREF scopes for a refinement for cme->owner, mirroring
        // the loop in search_refined_method.
        const rb_cref_t *c;
        for (c = cref; c; c = CREF_NEXT(c)) {
            VALUE refs = CREF_REFINEMENTS(c);
            if (NIL_P(refs)) continue;
            VALUE r = rb_hash_lookup(refs, cme->owner);
            if (NIL_P(r)) continue;
            r = rb_vm_refinement_iclass_for_cme(r, cme);
            const rb_callable_method_entry_t *ref_cme = rb_callable_method_entry(r, mid);
            if (!ref_cme) break;
            if (ref_cme->def->type == VM_METHOD_TYPE_REFINED) continue;
            if (skip_def && rb_method_definition_eq(ref_cme->def, skip_def)) continue;
            me = (rb_method_entry_t *)ref_cme;
            iclass = ref_cme->defined_class;
            break;
        }
        if (me) break;
        // No refined method found. Use orig_me if available, or normal method lookup
        // in superclass otherwise.
        const rb_method_entry_t *orig_me = cme->def->body.refined.orig_me;
        if (orig_me) {
            me = (rb_method_entry_t *)orig_me;
            iclass = cme->defined_class;
            break;
        }
        klass = RCLASS_SUPER(cme->defined_class);
    }
    if (!me) return Qnil;
    return mnew_internal(me, me->owner, iclass, data->recv, mid, rb_obj_class(method), FALSE, FALSE);
}