[10.x] Allow component slots to be empty, even if they have an html comment or line break

src/Illuminate/View/ComponentSlot.php

@@ -20,6 +20,13 @@ class ComponentSlot implements Htmlable
      */
     protected $contents;
 
+    /**
+     * The slot sanitizer.
+     *
+     * @var callable
+     */
+    protected $sanitizerResolver;
+
     /**
      * Create a new slot instance.
      *
@@ -32,6 +39,9 @@ public function __construct($contents = '', $attributes = [])
         $this->contents = $contents;
 
         $this->withAttributes($attributes);
+
+        // default sanitizer, return the input as it is
+        $this->sanitizerResolver = fn ($input) => $input;
     }
 
     /**
@@ -57,14 +67,37 @@ public function toHtml()
         return $this->contents;
     }
 
+    /**
+     * Setup the sanitizer for the slot.
+     *
+     * @param  null|string|callable  $callable
+     * @return $this
+     */
+    public function sanitize(null|string|callable $callable = null)
+    {
+        if (is_string($callable) && ! function_exists($callable)) {
+            throw new \InvalidArgumentException('Callable does not exist.');
+        }
+
+        $this->sanitizerResolver =
+            $callable ??
+            fn ($input) => trim(preg_replace("/<!--([\s\S]*?)-->/", '', $input)); // replace everything between <!-- and --> with empty string
+
+        return $this;
+    }
+
     /**
      * Determine if the slot is empty.
      *
+     * HTML comments and whitespace will be trimmed out.
+     *
      * @return bool
      */
     public function isEmpty()
     {
-        return $this->contents === '';
+        return filter_var($this->contents, FILTER_CALLBACK, [
+            'options' => $this->sanitizerResolver,
+        ]) === '';
     }
 
     /**

tests/View/ComponentTest.php

@@ -11,6 +11,7 @@
 use Illuminate\Support\Facades\Facade;
 use Illuminate\Support\HtmlString;
 use Illuminate\View\Component;
+use Illuminate\View\ComponentSlot;
 use Illuminate\View\Factory;
 use Illuminate\View\View;
 use Mockery as m;
@@ -305,6 +306,53 @@ public function testFactoryGetsSharedBetweenComponents()
         Component::forgetFactory();
         $this->assertNotSame($this->viewFactory, $getFactory($inline));
     }
+
+    public function testComponentSlotIsEmpty()
+    {
+        $slot = new ComponentSlot;
+
+        $this->assertTrue((bool) $slot->isEmpty());
+    }
+
+    public function testComponentSlotSanitizer()
+    {
+        // default sanitizer should remove all html tags
+        $slot = new ComponentSlot('<!-- test -->');
+
+        $linebreakingSlot = new ComponentSlot("\n  \t");
+
+        $moreComplexSlot = new ComponentSlot('<!--
+        <p>Look at this cool image:</p>
+        <img border="0" src="pic_trulli.jpg" alt="Trulli">
+        -->');
+
+        $whitespaceSlot = new ComponentSlot("\t  \n  \t  \n  \t");
+
+        $this->assertTrue((bool) $slot->sanitize()->isEmpty());
+        $this->assertTrue((bool) $linebreakingSlot->sanitize()->isEmpty());
+        $this->assertTrue((bool) $moreComplexSlot->sanitize()->isEmpty());
+
+        $this->assertTrue((bool) (clone $whitespaceSlot)->sanitize('trim')->isEmpty());
+        $this->assertTrue((bool) $whitespaceSlot->isNotEmpty());
+    }
+
+    public function testComponentSlotIsNotEmpty()
+    {
+        $slot = new ComponentSlot('test');
+
+        $anotherSlot = new ComponentSlot('test<!-- test -->');
+
+        $moreComplexSlot = new ComponentSlot('t<!--
+        <p>Look at this cool image:</p>
+        <img border="0" src="pic_trulli.jpg" alt="Trulli">
+        -->est');
+
+        $this->assertTrue((bool) $slot->isNotEmpty());
+
+        $this->assertTrue((bool) $anotherSlot->sanitize()->isNotEmpty());
+
+        $this->assertTrue((bool) $moreComplexSlot->sanitize()->isNotEmpty());
+    }
 }
 
 class TestInlineViewComponent extends Component