From c8ff4bd9b30b8ef480059a17db712beb4a77b89a Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Tue, 9 Apr 2019 15:29:40 -1000
Subject: [PATCH] Properly filter mapped types in getIndexType with
 noIndexSignatures=true

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

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 8e8f038c2d5..465371d0517 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -9848,7 +9848,7 @@ namespace ts {
             return type.flags & TypeFlags.Union ? getIntersectionType(map((<IntersectionType>type).types, t => getIndexType(t, stringsOnly, noIndexSignatures))) :
                 type.flags & TypeFlags.Intersection ? getUnionType(map((<IntersectionType>type).types, t => getIndexType(t, stringsOnly, noIndexSignatures))) :
                 maybeTypeOfKind(type, TypeFlags.InstantiableNonPrimitive) ? getIndexTypeForGenericType(<InstantiableType | UnionOrIntersectionType>type, stringsOnly) :
-                getObjectFlags(type) & ObjectFlags.Mapped ? getConstraintTypeFromMappedType(<MappedType>type) :
+                getObjectFlags(type) & ObjectFlags.Mapped ? filterType(getConstraintTypeFromMappedType(<MappedType>type), t => !(noIndexSignatures && t.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.Number))) :
                 type === wildcardType ? wildcardType :
                 type.flags & TypeFlags.Any ? keyofConstraintType :
                 stringsOnly ? !noIndexSignatures && getIndexInfoOfType(type, IndexKind.String) ? stringType : getLiteralTypeFromProperties(type, TypeFlags.StringLiteral) :