From cd7a14ac21974209fc870642e6d1489a66f91af1 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Wed, 22 May 2019 17:22:33 -0700
Subject: [PATCH] Reuse getSimplifiedTypeOrConstraint function

---
 src/compiler/checker.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index bd8d4c05901c7..386beb7f24dd7 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -13066,8 +13066,7 @@ namespace ts {
                     }
                     // A type S is assignable to keyof T if S is assignable to keyof C, where C is the
                     // simplified form of T or, if T doesn't simplify, the constraint of T.
-                    const simplified = getSimplifiedType((<IndexType>target).type, /*writing*/ false);
-                    const constraint = simplified !== (<IndexType>target).type ? simplified : getConstraintOfType((<IndexType>target).type);
+                    const constraint = getSimplifiedTypeOrConstraint((<IndexType>target).type);
                     if (constraint) {
                         // We require Ternary.True here such that circular constraints don't cause
                         // false positives. For example, given 'T extends { [K in keyof T]: string }',