From e15c70054963cd990d2c99fbaebfd0241bcf2c7b Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Thu, 9 Jul 2015 14:45:39 -0700
Subject: [PATCH] clean old program to prevent it from being captured into the
 closure

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

diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 2aeab800f0f..957b519af5e 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -188,6 +188,9 @@ namespace ts {
 
         verifyCompilerOptions();
 
+        // unconditionally set oldProgram to undefined to prevent it from being captured in closure
+        oldProgram = undefined;
+
         programTime += new Date().getTime() - start;
 
         program = {