(Flow) Preserve getter/setter info on ObjectTypeProperty (#1585)

* (Flow) Preserve getter/setter info on ObjectTypeProperty

Before: `type T = { get method(): void }` -> `type T = { method: () => void };`

Demo: https://prettier.github.io/prettier/#%7B%22content%22%3A%22type%20T%20%3D%20%7B%20get%20method()%3A%20void%20%7D%22%2C%22options%22%3A%7B%22printWidth%22%3A80%2C%22tabWidth%22%3A2%2C%22singleQuote%22%3Afalse%2C%22trailingComma%22%3A%22none%22%2C%22bracketSpacing%22%3Atrue%2C%22jsxBracketSameLine%22%3Afalse%2C%22parser%22%3A%22flow%22%2C%22semi%22%3Atrue%2C%22useTabs%22%3Afalse%2C%22doc%22%3Afalse%7D%7D

---

After: `type T = { get method(): void }` -> `type T = { get method(): void };`

Demo: `echo 'type T = { get method(): void }' | prettier --stdin --parser flow`

Demo: `echo 'type T = { get method(): void }' | prettier --stdin --parser flow --debug-check`

---

This passes `AST_COMPARE=1 npm test -- tests/flow/getters_and_setters_* tests/flow/objectTypeProperty/`
and fixes https://github.com/prettier/prettier/issues/1557

* (Flow) Make getter/setter parsing more robust

Addresses https://github.com/prettier/prettier/pull/1585#discussion_r116008715

src/printer.js

@@ -1989,10 +1989,11 @@ function genericPrintNoParens(path, options, print, args) {
 
       return concat([
         n.static ? "static " : "",
+        isGetterOrSetter ? n.kind + " " : "",
         variance || "",
         path.call(print, "key"),
         n.optional ? "?" : "",
-        (isFunctionNotation && !isGetterOrSetter) ? "" : ": ",
+        isFunctionNotation || isGetterOrSetter ? "" : ": ",
         path.call(print, "value")
       ]);
     case "QualifiedTypeIdentifier":
@@ -4125,11 +4126,12 @@ function isMemberExpressionChain(node) {
 // type T = { method: () => void };
 // type T = { method(): void };
 function isObjectTypePropertyAFunction(node) {
+  const isGetterOrSetter = node.kind === 'get' || node.kind === 'set';
   return (
     node.type === "ObjectTypeProperty" &&
     node.value.type === "FunctionTypeAnnotation" &&
     !node.static &&
-    util.locStart(node.key) !== util.locStart(node.value)
+    util.locStart(node.key) !== util.locStart(node.value) && !isGetterOrSetter
   );
 }
 

tests/flow/getters_and_setters_disabled/__snapshots__/jsfmt.spec.js.snap

@@ -52,14 +52,14 @@ var f = {
 };
 
 type T = {
-  a: () => number,
-  b: (x: number) => void,
+  get a(): number,
+  set b(x: number): void,
   c: 10
 };
 
 declare class Foo {
-  a: () => number,
-  b: (x: number) => void,
+  get a(): number,
+  set b(x: number): void,
   c: 10
 }
 

tests/flow/getters_and_setters_enabled/__snapshots__/jsfmt.spec.js.snap

@@ -197,28 +197,28 @@ foo.propOverriddenWithSetter = 123; // Error number ~> string
 var z: number = 123;
 
 declare class Foo {
-  goodGetterWithAnnotation: () => number,
-  goodSetterWithAnnotation: (x: number) => void,
+  get goodGetterWithAnnotation(): number,
+  set goodSetterWithAnnotation(x: number): void,
 
-  propWithMatchingGetterAndSetter: () => number,
-  propWithMatchingGetterAndSetter: (x: number) => void,
+  get propWithMatchingGetterAndSetter(): number,
+  set propWithMatchingGetterAndSetter(x: number): void,
 
   // The getter and setter need not have the same type - no error
-  propWithSubtypingGetterAndSetter: () => ?number,
-  propWithSubtypingGetterAndSetter: (x: number) => void,
+  get propWithSubtypingGetterAndSetter(): ?number,
+  set propWithSubtypingGetterAndSetter(x: number): void,
 
   // The getter and setter need not have the same type - no error
-  propWithSubtypingGetterAndSetterReordered: (x: number) => void,
-  propWithSubtypingGetterAndSetterReordered: () => ?number,
+  set propWithSubtypingGetterAndSetterReordered(x: number): void,
+  get propWithSubtypingGetterAndSetterReordered(): ?number,
 
-  propWithMismatchingGetterAndSetter: () => number,
-  propWithMismatchingGetterAndSetter: (x: string) => void, // doesn't match getter (OK)
+  get propWithMismatchingGetterAndSetter(): number,
+  set propWithMismatchingGetterAndSetter(x: string): void, // doesn't match getter (OK)
 
   propOverriddenWithGetter: number,
-  propOverriddenWithGetter: () => string,
+  get propOverriddenWithGetter(): string,
 
   propOverriddenWithSetter: number,
-  propOverriddenWithSetter: (x: string) => void
+  set propOverriddenWithSetter(x: string): void
 }
 
 var foo = new Foo();
@@ -455,24 +455,24 @@ class B extends A {}
 class C extends A {}
 
 type T = {
-  goodGetterWithAnnotation: () => number,
-  goodSetterWithAnnotation: (x: number) => void,
+  get goodGetterWithAnnotation(): number,
+  set goodSetterWithAnnotation(x: number): void,
 
-  propWithMatchingGetterAndSetter: () => number,
-  propWithMatchingGetterAndSetter: (x: number) => void,
+  get propWithMatchingGetterAndSetter(): number,
+  set propWithMatchingGetterAndSetter(x: number): void,
 
   // The getter and setter need not have the same type
-  propWithSubtypingGetterAndSetter: () => ?number, // OK
-  propWithSubtypingGetterAndSetter: (x: number) => void,
+  get propWithSubtypingGetterAndSetter(): ?number, // OK
+  set propWithSubtypingGetterAndSetter(x: number): void,
 
-  propWithSubtypingGetterAndSetterReordered: (x: number) => void, // OK
-  propWithSubtypingGetterAndSetterReordered: () => ?number,
+  set propWithSubtypingGetterAndSetterReordered(x: number): void, // OK
+  get propWithSubtypingGetterAndSetterReordered(): ?number,
 
-  exampleOfOrderOfGetterAndSetter: () => A,
-  exampleOfOrderOfGetterAndSetter: (x: B) => void,
+  get exampleOfOrderOfGetterAndSetter(): A,
+  set exampleOfOrderOfGetterAndSetter(x: B): void,
 
-  exampleOfOrderOfGetterAndSetterReordered: (x: B) => void,
-  exampleOfOrderOfGetterAndSetterReordered: () => A
+  set exampleOfOrderOfGetterAndSetterReordered(x: B): void,
+  get exampleOfOrderOfGetterAndSetterReordered(): A
 };
 
 function test(obj: T) {

tests/flow/objectTypeProperty/__snapshots__/jsfmt.spec.js.snap

@@ -15,6 +15,9 @@ let x: { x?: number }
 type T = {
   get goodGetterWithAnnotation(): number,
   set goodSetterWithAnnotation(x: number): void,
+
+  get  getterWithMultipleSpacesPrecedingName(): number,
+  set  setterWithMultipleSpacesPrecedingName(x: number): void,
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 /* @flow */
@@ -29,8 +32,11 @@ declare class Foo<T> {
 let x: { x?: number };
 
 type T = {
-  goodGetterWithAnnotation: () => number,
-  goodSetterWithAnnotation: (x: number) => void
+  get goodGetterWithAnnotation(): number,
+  set goodSetterWithAnnotation(x: number): void,
+
+  get getterWithMultipleSpacesPrecedingName(): number,
+  set setterWithMultipleSpacesPrecedingName(x: number): void
 };
 
 `;

tests/flow/objectTypeProperty/objectTypeProperty.js

@@ -12,4 +12,7 @@ let x: { x?: number }
 type T = {
   get goodGetterWithAnnotation(): number,
   set goodSetterWithAnnotation(x: number): void,
+
+  get  getterWithMultipleSpacesPrecedingName(): number,
+  set  setterWithMultipleSpacesPrecedingName(x: number): void,
 }