From a25104e152dcb34db31eaba16218e7ff9cc6eceb Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sat, 27 Aug 2016 09:40:49 -0700
Subject: [PATCH] Use union type when binding element has initializer

---
 src/compiler/checker.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 8c1e401912d..9afa1c1e2c3 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2974,7 +2974,9 @@ namespace ts {
             if (strictNullChecks && declaration.initializer && !(getFalsyFlags(checkExpressionCached(declaration.initializer)) & TypeFlags.Undefined)) {
                 type = getTypeWithFacts(type, TypeFacts.NEUndefined);
             }
-            return type;
+            return declaration.initializer ?
+                getUnionType([type, checkExpressionCached(declaration.initializer)], /*subtypeReduction*/ true) :
+                type;
         }
 
         function getTypeForVariableLikeDeclarationFromJSDocComment(declaration: VariableLikeDeclaration) {