lib/Twig/lib/Twig/TemplateWrapper.php
public function renderBlock($name, $context = array())
    {
        $context = $this->env->mergeGlobals($context);
        $level = ob_get_level();
        ob_start();
        try {
            $this->template->displayBlock($name, $context);
        } catch (Exception $e) {
            while (ob_get_level() > $level) {
                ob_end_clean();
            }

            throw $e;
        } catch (Throwable $e) {
            while (ob_get_level() > $level) {
                ob_end_clean();
            }

            throw $e;
        }

        return ob_get_clean();
    }
public function renderBlock($name, $context = array())
    {
        $context = $this->env->mergeGlobals($context);
        $level = ob_get_level();
        ob_start();
        try {
            $this->template->displayBlock($name, $context);
        } catch (Exception $e) {
            while (ob_get_level() > $level) {
                ob_end_clean();
            }

            throw $e;
        } catch (Throwable $e) {
            while (ob_get_level() > $level) {
                ob_end_clean();
            }

            throw $e;
        }

        return ob_get_clean();
    }
Renders a template block.

@param string $name    The block name to render
@param array  $context An array of parameters to pass to the template

@return string The rendered block