BUG: «adminhtml/system.xml» file indented with TAB character breaks Magento XML parser

[dmitrii-fediuk]

An example of «adminhtml/system.xml» file is below.

<?xml version='1.0'?>
<config
    xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
    xsi:noNamespaceSchemaLocation='../../../../Magento/Config/etc/system_file.xsd'
>
    <system>
     <section id="checkout" translate="label" type="text" sortOrder="305" showInDefault="1" showInWebsite="1" showInStore="1">
         <label>Checkout</label>
         <tab>sales</tab>
         <resource>Magento_Checkout::checkout</resource>
         <group id="options" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
             <label>Checkout Options</label>
             <field id="onepage_checkout_enabled" translate="label" type="select" sortOrder="5" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Enable Onepage Checkout</label>
                 <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
             </field>
         </group>
     </section>
 </system>
</config>

If the contents of config/system/section indented with tab character (instead of spaces) it breaks Magento XML parser with the trace below.
If change indents to spaces the parser works.

Warning: Invalid argument supplied for foreach() in app\code\Magento\Config\Model\Config\Structure\Mapper\Sorting.php on line 34
#0 app\code\Magento\Config\Model\Config\Structure\Mapper\Sorting.php(34): Magento\Framework\App\ErrorHandler->handler(2, 'Invalid argumen...', 'C:\\work\\mage2.p...', 34, Array)
#1 app\code\Magento\Config\Model\Config\Structure\Mapper\Sorting.php(23): Magento\Config\Model\Config\Structure\Mapper\Sorting->_processConfig('\n\t ')
#2 app\code\Magento\Config\Model\Config\Structure\Converter.php(64): Magento\Config\Model\Config\Structure\Mapper\Sorting->map(Array)
#3 [internal function]: Magento\Config\Model\Config\Structure\Converter->convert(Object(DOMDocument))
#4 lib\internal\Magento\Framework\Interception\Interceptor.php(144): call_user_func_array(Array, Array)
#5 var\generation\Magento\Config\Model\Config\Structure\Converter\Interceptor.php(26): Magento\Config\Model\Config\Structure\Converter\Interceptor->___callPlugins('convert', Array, Array)
#6 app\code\Magento\Config\Model\Config\Structure\Reader.php(115): Magento\Config\Model\Config\Structure\Converter\Interceptor->convert(Object(DOMDocument))
#7 lib\internal\Magento\Framework\Config\Reader\Filesystem.php(119): Magento\Config\Model\Config\Structure\Reader->_readFiles(Object(Magento\Framework\Config\FileIterator))
#8 lib\internal\Magento\Framework\Config\Data\Scoped.php(103): Magento\Framework\Config\Reader\Filesystem->read('adminhtml')
#9 lib\internal\Magento\Framework\Config\Data\Scoped.php(81): Magento\Framework\Config\Data\Scoped->_loadScopedData()
#10 app\code\Magento\Config\Model\Config\Structure.php(66): Magento\Framework\Config\Data\Scoped->get()
#11 var\generation\Magento\Config\Model\Config\Structure\Interceptor.php(14): Magento\Config\Model\Config\Structure->__construct(Object(Magento\Config\Model\Config\Structure\Data), Object(Magento\Config\Model\Config\Structure\Element\Iterator\Tab), Object(Magento\Config\Model\Config\Structure\Element\FlyweightFactory), Object(Magento\Config\Model\Config\ScopeDefiner))
#12 lib\internal\Magento\Framework\ObjectManager\Factory\AbstractFactory.php(103): Magento\Config\Model\Config\Structure\Interceptor->__construct(Object(Magento\Config\Model\Config\Structure\Data), Object(Magento\Config\Model\Config\Structure\Element\Iterator\Tab), Object(Magento\Config\Model\Config\Structure\Element\FlyweightFactory), Object(Magento\Config\Model\Config\ScopeDefiner))
#13 lib\internal\Magento\Framework\ObjectManager\Factory\Dynamic\Developer.php(91): Magento\Framework\ObjectManager\Factory\AbstractFactory->createObject('Magento\\Config\\...', Array)
#14 lib\internal\Magento\Framework\ObjectManager\ObjectManager.php(71): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->create('Magento\\Config\\...')
#15 lib\internal\Magento\Framework\ObjectManager\Factory\AbstractFactory.php(236): Magento\Framework\ObjectManager\ObjectManager->get('Magento\\Config\\...')
#16 lib\internal\Magento\Framework\ObjectManager\Factory\Dynamic\Developer.php(53): Magento\Framework\ObjectManager\Factory\AbstractFactory->resolveArgument(Array, 'Magento\\Config\\...', NULL, 'configStructure', 'Magento\\Config\\...')
#17 lib\internal\Magento\Framework\ObjectManager\Factory\Dynamic\Developer.php(84): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->_resolveArguments('Magento\\Config\\...', Array, Array)
#18 lib\internal\Magento\Framework\ObjectManager\ObjectManager.php(57): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->create('Magento\\Config\\...', Array)
#19 lib\internal\Magento\Framework\App\ActionFactory.php(40): Magento\Framework\ObjectManager\ObjectManager->create('Magento\\Config\\...', Array)
#20 lib\internal\Magento\Framework\App\Router\Base.php(301): Magento\Framework\App\ActionFactory->create('Magento\\Config\\...', Array)
#21 lib\internal\Magento\Framework\App\Router\Base.php(161): Magento\Framework\App\Router\Base->matchAction(Object(Magento\Framework\App\Request\Http), Array)
#22 lib\internal\Magento\Framework\App\FrontController.php(41): Magento\Framework\App\Router\Base->match(Object(Magento\Framework\App\Request\Http))
#23 [internal function]: Magento\Framework\App\FrontController->dispatch(Object(Magento\Framework\App\Request\Http))
#24 lib\internal\Magento\Framework\Interception\Interceptor.php(74): call_user_func_array(Array, Array)
#25 lib\internal\Magento\Framework\Interception\Chain\Chain.php(70): Magento\Framework\App\FrontController\Interceptor->___callParent('dispatch', Array)
#26 lib\internal\Magento\Framework\Interception\Interceptor.php(136): Magento\Framework\Interception\Chain\Chain->invokeNext('Magento\\Framewo...', 'dispatch', Object(Magento\Framework\App\FrontController\Interceptor), Array, 'install')
#27 lib\internal\Magento\Framework\Module\Plugin\DbStatusValidator.php(69): Magento\Framework\App\FrontController\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Framework\App\Request\Http))
#28 [internal function]: Magento\Framework\Module\Plugin\DbStatusValidator->aroundDispatch(Object(Magento\Framework\App\FrontController\Interceptor), Object(Closure), Object(Magento\Framework\App\Request\Http))
#29 lib\internal\Magento\Framework\Interception\Interceptor.php(141): call_user_func_array(Array, Array)
#30 var\generation\Magento\Framework\App\FrontController\Interceptor.php(26): Magento\Framework\App\FrontController\Interceptor->___callPlugins('dispatch', Array, Array)
#31 lib\internal\Magento\Framework\App\Http.php(115): Magento\Framework\App\FrontController\Interceptor->dispatch(Object(Magento\Framework\App\Request\Http))
#32 lib\internal\Magento\Framework\App\Bootstrap.php(257): Magento\Framework\App\Http->launch()
#33 index.php(39): Magento\Framework\App\Bootstrap->run(Object(Magento\Framework\App\Http))
#34 {main}

[piotrekkaminski]

internal ticket MAGETWO-40683

[dsikkema-magento]

@dfediuk I'm unable to reproduce this so far. Can you provide the detailed steps you went through to get that stack trace?

I went into app/code/Magento/Checkout/etc/adminhtml/system.xml, placed tab characters everywhere, and was able to access and modify store configuration.

[dsikkema-magento]

@dfediuk can you try with the latest code? It might have already been fixed by now.

[dsikkema-magento]

I'm going to close this ticket, but please feel free to open another one and tag me if you are still experiencing this issue.

[dmitrii-fediuk]

I have found the bug source and fix it: https://mage2.pro/t/topic/36/2
@dsikkema please fix it in the core.