From e9cb12aeab1241a520164221999d0916500df9f3 Mon Sep 17 00:00:00 2001
From: Paul van Brenk <paul.van.brenk@microsoft.com>
Date: Fri, 6 Mar 2015 14:29:23 -0800
Subject: [PATCH] Add diagnostics for signaturehelp crash

---
 src/services/signatureHelp.ts | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/services/signatureHelp.ts b/src/services/signatureHelp.ts
index 8b7dea13ead..e5ddb9012cc 100644
--- a/src/services/signatureHelp.ts
+++ b/src/services/signatureHelp.ts
@@ -264,12 +264,16 @@ module ts.SignatureHelp {
                     // the comma. That amounts to taking the ceiling of half the index.
                     var argumentIndex = (listItemInfo.listItemIndex + 1) >> 1;
 
+                    var argumentCount = getCommaBasedArgCount(list);
+
+                    Debug.assert(argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`); 
+
                     return {
                         kind: isTypeArgList ? ArgumentListKind.TypeArguments : ArgumentListKind.CallArguments,
                         invocation: callExpression,
                         argumentsSpan: getApplicableSpanForArguments(list),
                         argumentIndex: argumentIndex,
-                        argumentCount: getCommaBasedArgCount(list)
+                        argumentCount: argumentCount
                     };
                 }
             }
@@ -347,6 +351,8 @@ module ts.SignatureHelp {
                 ? 1
                 : (<TemplateExpression>tagExpression.template).templateSpans.length + 1;
 
+            Debug.assert(argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`); 
+
             return {
                 kind: ArgumentListKind.TaggedTemplateArguments,
                 invocation: tagExpression,
@@ -512,6 +518,8 @@ module ts.SignatureHelp {
                 selectedItemIndex = selectBestInvalidOverloadIndex(candidates, argumentCount);
             }
 
+            Debug.assert(argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`); 
+
             return {
                 items,
                 applicableSpan,