From e900ebf856c388a138befcd7a2e7445d88468981 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 24 Jun 2016 21:12:44 -0700
Subject: [PATCH] Make boolean assignable to union types containing both true
 and false

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

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b02918ddd28..ab5d4e9a5c4 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -6026,6 +6026,9 @@ namespace ts {
                         if (result = typeRelatedToSomeType(source, <UnionType>target, reportErrors && !(source.flags & TypeFlags.Primitive))) {
                             return result;
                         }
+                        if (source === booleanType && contains((<UnionType>target).types, trueType) && contains((<UnionType>target).types, falseType)) {
+                            return Ternary.True;
+                        }
                     }
                 }