Fixes #17190: SerializationException on ListViewItemCount (#17195)

* Fix issue #17190: SerializationException on ListViewItemCount

ListViewGroup doesn't (always) have a serialized member "ListViewItemCount".

This patch accounts for that and also adds support for the "ItemsCount"
property that upstream [1] seems to use.

Also items should be initialized regardless of the count, otherwise we get a NPE.

[1] https://github.com/dotnet/winforms/blob/master/src/System.Windows.Forms/src/System/Windows/Forms/ListViewGroup.cs#L144

1 files changed, 15 insertions, 7 deletions

diff --git a/mcs/class/System.Windows.Forms/System.Windows.Forms/ListViewGroup.cs b/mcs/class/System.Windows.Forms/System.Windows.Forms/ListViewGroup.cs
index 5d757d2c350..4386bca1fa5 100644
--- a/mcs/class/System.Windows.Forms/System.Windows.Forms/ListViewGroup.cs
+++ b/mcs/class/System.Windows.Forms/System.Windows.Forms/ListViewGroup.cs
@@ -84,15 +84,23 @@ namespace System.Windows.Forms
 			header_alignment = (HorizontalAlignment)info.GetInt32("HeaderAlignment");
 			tag = info.GetValue("Tag", typeof(object));
 
-			int count = info.GetInt32("ListViewItemCount");
-			if (count > 0) {
-				if(items == null)
+			int count = 0;
+			try {
+				count = info.GetInt32("ItemsCount");
+			} catch (SerializationException e) {
+				// Mono backwards compat
+				try {
+ 					count = info.GetInt32("ListViewItemCount");
+				} catch (SerializationException e2) {}
+			}
+
+			if (items == null) {
 				items = new ListView.ListViewItemCollection(list_view_owner);
+			}
 
-				for (int i = 0; i < count; i++)
-				{
-					items.Add((ListViewItem)info.GetValue(string.Format("ListViewItem_{0}", i), typeof(ListViewItem)));
-				}
+			for (int i = 0; i < count; i++)
+			{
+				items.Add((ListViewItem)info.GetValue(string.Format("ListViewItem_{0}", i), typeof(ListViewItem)));
 			}
 		}