use getBaseTypeOfLiteralType

src/compiler/checker.ts

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

src/compiler/types.ts

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

src/services/codefixes/fixAddMissingMember.ts

@@ -30,6 +30,22 @@ namespace ts.codefix {
 
         // if function call, synthesize function declaration
         if(token.parent.parent.kind == SyntaxKind.CallExpression) {
+            const callExpression = token.parent.parent as CallExpression;
+            if(callExpression.typeArguments) {
+                /**
+                 * We can't in general know which arguments should use the type of the expression
+                 * or the type of the type argument in the declaration. Consider
+                 * ```
+                 * class A {
+                 *     constructor(a: number){
+                 *         this.foo<number>(a,1,true);
+                 *     }
+                 * }
+                 * ```
+                 */
+                return undefined;
+            }
+
 
         }
 
@@ -41,8 +57,8 @@ namespace ts.codefix {
             binaryExpression.operatorToken;
 
             const checker = context.program.getTypeChecker();
-            const type = checker.getWidenedType(checker.getTypeAtLocation(binaryExpression.right));
-            typeString = checker.typeToString(type);
+            const widenedType = checker.getBaseTypeOfLiteralType(checker.getTypeAtLocation(binaryExpression.right));
+            typeString = checker.typeToString(widenedType);
         }
 
         return [{

src/services/tsconfig.json

@@ -78,6 +78,7 @@
         "formatting/smartIndenter.ts",
         "formatting/tokenRange.ts",
         "codeFixProvider.ts",
+        "codefixes/fixAddMissingMember.ts",
         "codefixes/fixExtendsInterfaceBecomesImplements.ts",
         "codefixes/fixClassIncorrectlyImplementsInterface.ts",
         "codefixes/fixClassDoesntImplementInheritedAbstractMember.ts",