From 40e117a1a5fa219f393df53c9fc4f77c92f41b91 Mon Sep 17 00:00:00 2001
From: Vasily Kirichenko <vaskir@gmail.com>
Date: Sat, 14 Oct 2017 17:48:35 +0300
Subject: [PATCH] fix IndexOutOfRange exception in advanced completion

---
 src/fsharp/vs/service.fs | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/fsharp/vs/service.fs b/src/fsharp/vs/service.fs
index d387ca9702a..a6af069f33b 100644
--- a/src/fsharp/vs/service.fs
+++ b/src/fsharp/vs/service.fs
@@ -567,14 +567,17 @@ type TypeCheckInfo
             | Item.Value _ -> CompletionItemKind.Field
             | _ -> CompletionItemKind.Other
 
+        let getNamespace (idents: Idents) = 
+            if idents.Length > 1 then Some idents.[..idents.Length - 2] else None
+
         let unresolved =
             unresolvedEntity
             |> Option.map (fun x ->
-                let ns =
-                    match x.TopRequireQualifiedAccessParent with
-                    | Some parent when not (Array.isEmpty parent) -> 
-                        parent.[..parent.Length - 2]
-                    | _ -> x.CleanedIdents.[..x.CleanedIdents.Length - 2]
+                let ns = 
+                    x.TopRequireQualifiedAccessParent 
+                    |> Option.bind getNamespace 
+                    |> Option.orElseWith (fun () -> getNamespace x.CleanedIdents)
+                    |> Option.defaultValue [||]
 
                 let displayName = x.CleanedIdents |> Array.skip ns.Length |> String.concat "."