From e7c8c84d5de318ebe55c4fa2f1fdfb7e6a058902 Mon Sep 17 00:00:00 2001
From: nosoop <nosoop@users.noreply.github.com>
Date: Tue, 20 Sep 2022 07:24:08 -0700
Subject: [PATCH] entitylump: Fix behavior of append (#1836)

This change ensures that the iterator values used by `std::distance`
is correct.  Having the emplace within leads to the possibility of
`m_Entities.begin()` being invalidated due to reallocations.
---
 core/logic/LumpManager.cpp | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/core/logic/LumpManager.cpp b/core/logic/LumpManager.cpp
index d6b1eb7ff..316499277 100644
--- a/core/logic/LumpManager.cpp
+++ b/core/logic/LumpManager.cpp
@@ -122,10 +122,8 @@ void EntityLumpManager::Insert(size_t index) {
 }
 
 size_t EntityLumpManager::Append() {
-	return std::distance(
-			m_Entities.begin(),
-			m_Entities.emplace(m_Entities.end(), std::make_shared<EntityLumpEntry>())
-	);
+	auto it = m_Entities.emplace(m_Entities.end(), std::make_shared<EntityLumpEntry>());
+	return std::distance(m_Entities.begin(), it);
 }
 
 size_t EntityLumpManager::Length() {