From 16d196e986cbb30d15e7495fcfa8515dfb323da3 Mon Sep 17 00:00:00 2001
From: Alexander Ebert <ebert@woltlab.com>
Date: Tue, 24 Aug 2021 23:23:55 +0200
Subject: [PATCH] Prevent the menu item itself being selected as its parent
 item

See https://community.woltlab.com/thread/291999-men%C3%BCpunkt-verschwindet-wenn-%C3%BCbergeordneter-men%C3%BCpunkt-der-gleiche-ist/
---
 .../install/files/acp/templates/menuItemAdd.tpl     |  8 +++++++-
 .../files/lib/acp/form/MenuItemEditForm.class.php   | 13 +++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/wcfsetup/install/files/acp/templates/menuItemAdd.tpl b/wcfsetup/install/files/acp/templates/menuItemAdd.tpl
index acf5734293..c99a7396d9 100644
--- a/wcfsetup/install/files/acp/templates/menuItemAdd.tpl
+++ b/wcfsetup/install/files/acp/templates/menuItemAdd.tpl
@@ -71,7 +71,13 @@
 					<option value="0">{lang}wcf.global.noSelection{/lang}</option>
 					
 					{foreach from=$menuItemNodeList item=menuItemNode}
-						<option value="{@$menuItemNode->itemID}"{if $menuItemNode->itemID == $parentItemID} selected{/if}>{if $menuItemNode->getDepth() > 1}{@"&nbsp;&nbsp;&nbsp;&nbsp;"|str_repeat:($menuItemNode->getDepth() - 1)}{/if}{$menuItemNode->getTitle()}</option>
+						<option
+							value="{@$menuItemNode->itemID}"
+							{if $menuItemNode->itemID == $parentItemID} selected{/if}
+							{if $menuItemNode->itemID == $itemID} disabled{/if}
+						>
+							{if $menuItemNode->getDepth() > 1}{@"&nbsp;&nbsp;&nbsp;&nbsp;"|str_repeat:($menuItemNode->getDepth() - 1)}{/if}{$menuItemNode->getTitle()}
+						</option>
 					{/foreach}
 				</select>
 				{if $errorField == 'parentItemID'}
diff --git a/wcfsetup/install/files/lib/acp/form/MenuItemEditForm.class.php b/wcfsetup/install/files/lib/acp/form/MenuItemEditForm.class.php
index 03b11f02c3..2cfc6fd1a1 100644
--- a/wcfsetup/install/files/lib/acp/form/MenuItemEditForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/MenuItemEditForm.class.php
@@ -8,6 +8,7 @@ use wcf\data\menu\Menu;
 use wcf\data\page\PageNodeTree;
 use wcf\form\AbstractForm;
 use wcf\system\exception\IllegalLinkException;
+use wcf\system\exception\UserInputException;
 use wcf\system\language\I18nHandler;
 use wcf\system\page\handler\ILookupPageHandler;
 use wcf\system\WCF;
@@ -69,6 +70,18 @@ class MenuItemEditForm extends MenuItemAddForm
         }
     }
 
+    /**
+     * @inheritDoc
+     */
+    public function validate()
+    {
+        parent::validate();
+
+        if ($this->parentItemID == $this->itemID) {
+            throw new UserInputException('parentItemID');
+        }
+    }
+
     /**
      * @inheritDoc
      */
-- 
2.20.1