Fix capturing output from extensions that still use echo

src/Node/CaptureNode.php

@@ -43,8 +43,9 @@ class CaptureNode extends Node
         $compiler
             ->indent()
             ->subcompile($this->getNode('body'))
+            ->write("return; yield '';\n")
             ->outdent()
-            ->write("})() ?? new \EmptyIterator()")
+            ->write('})()')
         ;
         if ($useYield) {
             $compiler->raw(', false))');

tests/EnvironmentTest.php

@@ -414,7 +414,7 @@ class EnvironmentTest extends TestCase
      */
     public function testLegacyEchoingNode()
     {
-        $loader = new ArrayLoader(['echo_bar' => 'A{% set v %}B{% test %}C{% endset %}D{% test %}E{{ v }}F']);
+        $loader = new ArrayLoader(['echo_bar' => 'A{% set v %}B{% test %}C{% endset %}D{% test %}E{{ v }}F{% set w %}{% test %}{% endset %}G{{ w }}H']);
 
         $twig = new Environment($loader);
         $twig->addExtension(new EnvironmentTest_Extension());
@@ -430,7 +430,7 @@ EOF
             );
         }
 
-        $this->assertSame('ADbarEBbarCF', $twig->render('echo_bar'));
+        $this->assertSame('ADbarEBbarCFGbarH', $twig->render('echo_bar'));
     }
 
     protected function getMockLoader($templateName, $templateContent)

tests/Node/MacroTest.php

@@ -60,7 +60,8 @@ public function macro_foo(\$__foo__ = null, \$__bar__ = "Foo", ...\$__varargs__)
 
     return new Markup(implode('', iterator_to_array((function () use (\$context, \$macros, \$blocks) {
         yield "foo";
-    })() ?? new \EmptyIterator(), false)), \$this->env->getCharset());
+        return; yield '';
+    })(), false)), \$this->env->getCharset());
 }
 EOF
             , new Environment(new ArrayLoader()),

tests/Node/SetTest.php

@@ -57,7 +57,8 @@ EOF
 // line 1
 \$context["foo"] = ('' === \$tmp = implode('', iterator_to_array((function () use (&\$context, \$macros, \$blocks) {
     yield "foo";
-})() ?? new \EmptyIterator(), false))) ? '' : new Markup(\$tmp, \$this->env->getCharset());
+    return; yield '';
+})(), false))) ? '' : new Markup(\$tmp, \$this->env->getCharset());
 EOF
                 , new Environment(new ArrayLoader()),
             ];
@@ -66,7 +67,8 @@ EOF
 // line 1
 $context["foo"] = ('' === $tmp = \Twig\Extension\CoreExtension::captureOutput((function () use (&$context, $macros, $blocks) {
     yield "foo";
-})() ?? new \EmptyIterator())) ? '' : new Markup($tmp, $this->env->getCharset());
+    return; yield '';
+})())) ? '' : new Markup($tmp, $this->env->getCharset());
 EOF
                 , new Environment(new ArrayLoader()),
             ];