From 8799b7b01eb163af8dfce0c6ee630e9345103b03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Ludwig?= <sludwig@rejectedsoftware.com>
Date: Tue, 26 Sep 2017 15:42:23 +0200
Subject: [PATCH] Add assertion.

---
 source/eventcore/internal/dlist.d | 1 +
 1 file changed, 1 insertion(+)

diff --git a/source/eventcore/internal/dlist.d b/source/eventcore/internal/dlist.d
index 5186fc8..8358e5d 100644
--- a/source/eventcore/internal/dlist.d
+++ b/source/eventcore/internal/dlist.d
@@ -59,6 +59,7 @@ struct StackDList(T) {
 
 	void insertAfter(T* item, T* after)
 	{
+		assert(!item.prev && !item.next);
 		if (!after) insertBack(item);
 		else {
 			item.prev = after;