core-bundle/src/Resources/contao/library/Contao/System.php
public static function convertXlfToPhp($strName, $strLanguage, $blnLoad=false)
	{
		@trigger_error('Using System::convertXlfToPhp() has been deprecated and will no longer work in Contao 5.0. Use the Contao\CoreBundle\Config\Loader\XliffFileLoader instead.', E_USER_DEPRECATED);

		$rootDir = self::getContainer()->getParameter('kernel.project_dir');

		// Convert to absolute path
		if (strpos($strName, $rootDir . '/') === false)
		{
			$strName = $rootDir . '/' . $strName;
		}

		$loader = new XliffFileLoader(static::getContainer()->getParameter('kernel.project_dir'), $blnLoad);

		return $loader->load($strName, $strLanguage);
	}
public static function convertXlfToPhp($strName, $strLanguage, $blnLoad=false)
	{
		@trigger_error('Using System::convertXlfToPhp() has been deprecated and will no longer work in Contao 5.0. Use the Contao\CoreBundle\Config\Loader\XliffFileLoader instead.', E_USER_DEPRECATED);

		$rootDir = self::getContainer()->getParameter('kernel.project_dir');

		// Convert to absolute path
		if (strpos($strName, $rootDir . '/') === false)
		{
			$strName = $rootDir . '/' . $strName;
		}

		$loader = new XliffFileLoader(static::getContainer()->getParameter('kernel.project_dir'), $blnLoad);

		return $loader->load($strName, $strLanguage);
	}
Convert an .xlf file into a PHP language file

@param string  $strName     The name of the .xlf file
@param string  $strLanguage The language code
@param boolean $blnLoad     Add the labels to the global language array

@return string The PHP code

@deprecated Deprecated since Contao 4.0, to be removed in Contao 5.0.
Use the Contao\CoreBundle\Config\Loader\XliffFileLoader instead.