Fix type annotation for optional function type properties

src/printer.js

@@ -1332,7 +1332,7 @@ function genericPrintNoParens(path, options, print) {
       // var A: (a: B) => void;
       var parent = path.getParentNode(0);
       var isArrowFunctionTypeAnnotation = !(
-        (!parent.variance && namedTypes.ObjectTypeProperty.check(parent)) ||
+        (!parent.variance && !parent.optional && namedTypes.ObjectTypeProperty.check(parent)) ||
         namedTypes.ObjectTypeCallProperty.check(parent) ||
         namedTypes.DeclareFunction.check(path.getParentNode(2))
       );
@@ -1444,7 +1444,9 @@ function genericPrintNoParens(path, options, print) {
       var variance =
         n.variance === "plus" ? "+" :
         n.variance === "minus" ? "-" : "";
-      var isFunction = !n.variance && n.value.type === "FunctionTypeAnnotation";
+      // TODO: This is a bad hack and we need a better way to know
+      // when to emit an arrow function or not.
+      var isFunction = !n.variance && !n.optional && n.value.type === "FunctionTypeAnnotation";
 
       return concat([
         n.static ? "static " : "",

tests/method_properties/__snapshots__/jsfmt.spec.js.snap

@@ -8,7 +8,7 @@ declare class Foo {
 export {Foo};
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // @flow
-declare class Foo { bar?(): string }
+declare class Foo { bar?: () => string }
 export { Foo }
 "
 `;
@@ -24,7 +24,7 @@ C.x;
 (new C).foo.x;
 C.bar.x;
 
-import {Foo} from './exports_optional_prop';
+import {Foo} from \'./exports_optional_prop\';
 const foo = new Foo();
 (foo.bar(): string); // error, could be undefined
 
@@ -52,7 +52,7 @@ class C {
 C.x;
 new C().foo.x;
 C.bar.x;
-import { Foo } from "./exports_optional_prop";
+import { Foo } from \"./exports_optional_prop\";
 const foo = new Foo();
 (foo.bar(): string);
 function f(x) {

tests/refinements/__snapshots__/jsfmt.spec.js.snap

@@ -490,7 +490,7 @@ function bar(x:Object) {
 // treated as \`any\`, so allowed
 // still treated as \`any\`, so allowed
 // also treated as \`any\`, so allowed
-function foo(x: { y?(): void }) {
+function foo(x: { y?: () => void }) {
   x.y();
   if (x.hasOwnProperty(\"y\")) {
     x.y();
@@ -708,7 +708,7 @@ exports[`test lib.js 1`] = `
 declare var BAZ: {stuff?: (x: number) => void} | void;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 /* @flow */
-declare var BAZ: { stuff?(x: number): void } | void;
+declare var BAZ: { stuff?: (x: number) => void } | void;
 "
 `;