From e8425f9e52c9df0ce0fbf122adff3ef6930f9961 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorbj=C3=B8rn=20Lund=20Martsum?= <tmartsum@gmail.com>
Date: Wed, 28 Feb 2018 09:23:54 +0100
Subject: QHeaderView: Fix crash in layout about to change

Before there was a risk looking up e.g index -1 if there
were no visible sections in layoutAboutToChange.

Change-Id: Ic911e4292e8e8c4892fef1c0f34cf7dccaad2bac
Task-number: QTBUG-65478
Reviewed-by: David Faure <david.faure@kdab.com>
---
diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 26d7c5472a..708b9b44ca 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -2163,9 +2163,11 @@ void QHeaderViewPrivate::_q_sectionsAboutToBeChanged()
     layoutChangePersistentSections.clear();
     layoutChangePersistentSections.reserve(std::min(10, sectionItems.count()));
     // after layoutChanged another section can be last stretched section
-    if (stretchLastSection) {
+    if (stretchLastSection && lastSectionLogicalIdx >= 0 && lastSectionLogicalIdx < sectionItems.count()) {
         const int visual = visualIndex(lastSectionLogicalIdx);
-        sectionItems[visual].size = lastSectionSize;
+        if (visual >= 0 && visual < sectionItems.size()) {
+            sectionItems[visual].size = lastSectionSize;
+        }
     }
     for (int i = 0; i < sectionItems.size(); ++i) {
         auto s = sectionItems.at(i);