[BUGFIX] Fix contentAs feature when used on Layout level

`<f:render section="MySection" contentAs="content">some content</f:section>`
did not work when called from a Layout because the `contentAs` variable was
not passed to the template section in that case.

examples/Resources/Private/Layouts/ContentAs.html

@@ -0,0 +1,3 @@
+<f:layout name="ContentAs" />
+
+<f:render section="Main" contentAs="content">Content from layout via contentAs</f:section>

examples/Resources/Private/Singles/ContentFromLayout.html

@@ -0,0 +1,5 @@
+<f:layout name="ContentAs" />
+
+<f:section name="Main">
+{content}
+</f:section>

examples/example_layoutcontentas.php

@@ -0,0 +1,26 @@
+<?php
+
+/*
+ * EXAMPLE: MVC pattern used with TYPO3.Fluid
+ *
+ * This examples shows how TYPO3.Fluid is integrated
+ * in an MVC context, highlighting which parts may
+ * be replaced in order to adapt the engine to your
+ * favorite MVC framework.
+ *
+ * The alternative to this is single file rendering
+ * - see the other example for that.
+ */
+
+require __DIR__ . '/include/view_init.php';
+
+// Assign Layout name as ViewVariable which we will pass to f:layout as name
+$view->assign('layout', 'Dynamic');
+
+// Set the template path and filename we will render
+$view->getTemplatePaths()->setTemplatePathAndFilename(__DIR__ . '/Resources/Private/Singles/ContentFromLayout.html');
+
+$output = $view->render();
+
+// Output of Controller "Default" action "Default" using helper from view_init.php
+example_output($output);

src/View/AbstractTemplateView.php

@@ -217,15 +217,17 @@ function($parent, TemplatePaths $paths) use ($layoutName) {
     public function renderSection($sectionName, array $variables = [], $ignoreUnknown = false)
     {
         $renderingContext = $this->getCurrentRenderingContext();
-
+        $renderingTypeOnNextLevel = $this->getCurrentRenderingType();
         if ($this->getCurrentRenderingType() === self::RENDERING_LAYOUT) {
             // in case we render a layout right now, we will render a section inside a TEMPLATE.
             $renderingTypeOnNextLevel = self::RENDERING_TEMPLATE;
-        } else {
-            $renderingContext = clone $renderingContext;
-            $renderingContext->setVariableProvider($renderingContext->getVariableProvider()->getScopeCopy($variables));
-            $renderingTypeOnNextLevel = $this->getCurrentRenderingType();
+            if (empty($variables)) {
+                $variables = $renderingContext->getVariableProvider()->getAll();
+            }
         }
+        $variableProvider = $renderingContext->getVariableProvider()->getScopeCopy($variables);
+        $renderingContext = clone $renderingContext;
+        $renderingContext->setVariableProvider($variableProvider);
 
         try {
             $parsedTemplate = $this->getCurrentParsedTemplate();

tests/Functional/ExamplesTest.php

@@ -240,6 +240,12 @@ public function getExampleScriptTestValues()
                     'Rendered via DynamicLayout, section "Main":',
                 ]
             ],
+            'example_layoutcontentas.php' => [
+                'example_layoutcontentas.php',
+                [
+                    'Content from layout via contentAs',
+                ]
+            ],
             'example_cachestatic.php' => [
                 'example_cachestatic.php',
                 [

tests/Unit/View/TemplatePathsTest.php

@@ -220,6 +220,7 @@ public function testResolveFilesInFolders()
             [['examples/Resources/Private/Layouts/', 'examples/Resources/Private/Templates/Default/'], 'html']
         );
         $expected = [
+            'examples/Resources/Private/Layouts/ContentAs.html',
             'examples/Resources/Private/Layouts/Default.html',
             'examples/Resources/Private/Layouts/Dynamic.html',
             'examples/Resources/Private/Templates/Default/Default.html',