Retain spaceless tag in Twig

modules/system/twig/Extension.php

@@ -84,7 +84,9 @@ public function getFilters()
      */
     public function getTokenParsers()
     {
-        $parsers = [];
+        $parsers = [
+            new SpacelessTokenParser
+        ];
 
         /*
          * Include extensions provided by plugins

modules/system/twig/SpacelessNode.php

@@ -0,0 +1,38 @@
+<?php namespace System\Twig;
+
+use Twig\Compiler;
+use Twig\Node\Node;
+use Twig\Node\NodeOutputInterface;
+
+/**
+ * Represents a spaceless node.
+ *
+ * It removes spaces between HTML tags.
+ *
+ * Removed in Twig 3.0, but retained in Winter CMS for compatibility.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class SpacelessNode extends Node implements NodeOutputInterface
+{
+    public function __construct(Node $body, int $lineno, string $tag = 'spaceless')
+    {
+        parent::__construct(['body' => $body], [], $lineno, $tag);
+    }
+
+    public function compile(Compiler $compiler)
+    {
+        $compiler
+            ->addDebugInfo($this)
+        ;
+        if ($compiler->getEnvironment()->isDebug()) {
+            $compiler->write("ob_start();\n");
+        } else {
+            $compiler->write("ob_start(function () { return ''; });\n");
+        }
+        $compiler
+            ->subcompile($this->getNode('body'))
+            ->write("echo trim(preg_replace('/>\s+</', '><', ob_get_clean()));\n")
+        ;
+    }
+}

modules/system/twig/SpacelessTokenParser.php

@@ -0,0 +1,29 @@
+<?php namespace System\Twig;
+
+use Twig\Token;
+use Twig\TokenParser\AbstractTokenParser;
+
+final class SpacelessTokenParser extends AbstractTokenParser
+{
+    public function parse(Token $token)
+    {
+        $stream = $this->parser->getStream();
+        $lineno = $token->getLine();
+
+        $stream->expect(/* Token::BLOCK_END_TYPE */ 3);
+        $body = $this->parser->subparse([$this, 'decideSpacelessEnd'], true);
+        $stream->expect(/* Token::BLOCK_END_TYPE */ 3);
+
+        return new SpacelessNode($body, $lineno, $this->getTag());
+    }
+
+    public function decideSpacelessEnd(Token $token)
+    {
+        return $token->test('endspaceless');
+    }
+
+    public function getTag()
+    {
+        return 'spaceless';
+    }
+}

tests/unit/system/twig/SpacelessTest.php

@@ -0,0 +1,25 @@
+<?php
+
+class SpacelessTest extends TestCase
+{
+    public function testSpacelessNode()
+    {
+        $twig = $this->app->make('twig.environment');
+        $template = $twig->createTemplate(
+            '<p>Test</p>
+
+            {% spaceless %}
+                <p class="test-1 test-2">This is a sentence.</p>
+
+                <p> This is another sentence.</p>
+            {% endspaceless %}'
+        );
+
+        $this->assertEquals(
+            '<p>Test</p>
+
+            <p class="test-1 test-2">This is a sentence.</p><p> This is another sentence.</p>',
+            $template->render()
+        );
+    }
+}