Get Widened Type

src/compiler/checker.ts

@@ -83,6 +83,7 @@ namespace ts {
             getSignaturesOfType,
             getIndexTypeOfType,
             getBaseTypes,
+            getWidenedType,
             getTypeFromTypeNode,
             getParameterType: getTypeAtPosition,
             getReturnTypeOfSignature,

src/compiler/diagnosticMessages.json

@@ -3303,6 +3303,14 @@
         "category": "Message",
         "code": 90015
     },
+    "Add declaration for missing property '{0}'": {
+        "category": "Message",
+        "code": 90016
+    },
+    "Add index accessor for missing property '{0}'": {
+        "category": "Message",
+        "code": 90017
+    },
     "Octal literal types must use ES2015 syntax. Use the syntax '{0}'.": {
         "category": "Error",
         "code": 8017

src/compiler/types.ts

@@ -2382,6 +2382,7 @@
         getSignaturesOfType(type: Type, kind: SignatureKind): Signature[];
         getIndexTypeOfType(type: Type, kind: IndexKind): Type;
         getBaseTypes(type: InterfaceType): BaseType[];
+        getWidenedType(type: Type): Type;
         getReturnTypeOfSignature(signature: Signature): Type;
         /**
          * Gets the type of a parameter at a given position in a signature.