Regression in 3.1.28 - Cannot traverse an already closed generator

[dendemann]

After updating from 3.1.27 to 3.1.28 a smarty foreach looping a generator does not work anymore. An exception "Cannot traverse an already closed generator" is thrown.

Looking at the smarty cache, it seems that the newer version introduces an additional Smarty_Internal_Runtime_Foreach::count that might be the problem.

$_from contains the generator.

3.1.27:

<?php
$_from = $_smarty_tpl->tpl_vars['mail_list']->value['page_links']->get_pages();
if (!is_array($_from) && !is_object($_from)) {
settype($_from, 'array');
}
$_smarty_tpl->tpl_vars["page"] = new Smarty_Variable;
$_smarty_tpl->tpl_vars["page"]->_loop = false;
foreach ($_from as $_smarty_tpl->tpl_vars["page"]->value) {
$_smarty_tpl->tpl_vars["page"]->_loop = true;
$foreach_page_Sav = $_smarty_tpl->tpl_vars["page"];
?>

3.1.28:

<?php
$_from = $_smarty_tpl->tpl_vars['mail_list']->value['page_links']->get_pages();
if (!is_array($_from) && !is_object($_from)) {
settype($_from, 'array');
}
$__foreach_page_3_saved_item = isset($_smarty_tpl->tpl_vars['page']) ? $_smarty_tpl->tpl_vars['page'] : false;
$_smarty_tpl->tpl_vars['page'] = new Smarty_Variable();
$__foreach_page_3_total = $_smarty_tpl->smarty->ext->_foreach->count($_from);
if ($__foreach_page_3_total) {
foreach ($_from as $_smarty_tpl->tpl_vars['page']->value) {
$__foreach_page_3_saved_local_item = $_smarty_tpl->tpl_vars['page'];
?>

[dendemann]

Here is a small sample that can be used to reproduce the issue:

  $generator = function() {
    yield 1;
  };

  $smarty = new Smarty();
  $smarty->assign('generator', $generator());
  $smarty->display('string:{foreach item="x" from=$generator}{$x}{/foreach}');

[uwetews]

The fix is now in the master branch.

Reason was that Generator is an Iterator where a call to iterator_count does close it and which can not be rewind.