PhpCsFixer\Fixer\Casing\NativeFunctionCasingFixer::getNativeFunctionNames PHP Метод

    private function getNativeFunctionNames()
    {
        $allFunctions = get_defined_functions();
        $functions = array();
        foreach ($allFunctions['internal'] as $function) {
            $functions[strtolower($function)] = $function;
        }
        return $functions;
    }