From 785cb5597724c698b59d06bcc65904c34c3720d7 Mon Sep 17 00:00:00 2001
From: Cyrus Najmabadi <cyrusn@microsoft.com>
Date: Tue, 31 Mar 2015 14:32:36 -0700
Subject: [PATCH] Add explanatory comment.

---
 src/compiler/checker.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 5d1c38eb827..80ccd46e6c4 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3327,6 +3327,8 @@ module ts {
             if (!links.resolvedType) {
                 let type: Type;
 
+                // We don't currently support heritage clauses with complex expressions in them.
+                // For these cases, we just set the type to be the unknownType.
                 if (node.kind !== SyntaxKind.HeritageClauseElement || isSupportedHeritageClauseElement(<HeritageClauseElement>node)) {
                     let typeNameOrExpression = node.kind === SyntaxKind.TypeReference
                         ? (<TypeReferenceNode>node).typeName