TypeScript 4.0: Support labeled tuple elements (#11754)

* TypeScript 4.0: Support labeled tuple elements

* More tests

* Disallow mixing labeled and unlabeled elements

* Update AST shape

* Enable test after rebase

* Allow labeled spread types

* Fix flow

* Add types and generator suport

* Update packages/babel-parser/src/plugins/typescript/index.js

* Prettier

packages/babel-types/src/asserts/generated/index.js

@@ -923,6 +923,12 @@ export function assertTSOptionalType(node: Object, opts?: Object = {}): void {
 export function assertTSRestType(node: Object, opts?: Object = {}): void {
   assert("TSRestType", node, opts);
 }
+export function assertTSNamedTupleMember(
+  node: Object,
+  opts?: Object = {},
+): void {
+  assert("TSNamedTupleMember", node, opts);
+}
 export function assertTSUnionType(node: Object, opts?: Object = {}): void {
   assert("TSUnionType", node, opts);
 }

packages/babel-types/src/builders/generated/index.js

@@ -894,6 +894,11 @@ export function tsRestType(...args: Array<any>): Object {
 }
 export { tsRestType as TSRestType };
 export { tsRestType as tSRestType };
+export function tsNamedTupleMember(...args: Array<any>): Object {
+  return builder("TSNamedTupleMember", ...args);
+}
+export { tsNamedTupleMember as TSNamedTupleMember };
+export { tsNamedTupleMember as tSNamedTupleMember };
 export function tsUnionType(...args: Array<any>): Object {
   return builder("TSUnionType", ...args);
 }

packages/babel-types/src/definitions/typescript.js

@@ -214,7 +214,7 @@ defineType("TSTupleType", {
   aliases: ["TSType"],
   visitor: ["elementTypes"],
   fields: {
-    elementTypes: validateArrayOfType("TSType"),
+    elementTypes: validateArrayOfType(["TSType", "TSNamedTupleMember"]),
   },
 });
 
@@ -234,6 +234,19 @@ defineType("TSRestType", {
   },
 });
 
+defineType("TSNamedTupleMember", {
+  visitor: ["label", "elementType"],
+  builder: ["label", "elementType", "optional"],
+  fields: {
+    label: validateType("Identifier"),
+    optional: {
+      validate: bool,
+      default: false,
+    },
+    elementType: validateType("TSType"),
+  },
+});
+
 const unionOrIntersection = {
   aliases: ["TSType"],
   visitor: ["types"],

packages/babel-types/src/validators/generated/index.js

@@ -3041,6 +3041,20 @@ export function isTSRestType(node: ?Object, opts?: Object): boolean {
 
   return false;
 }
+export function isTSNamedTupleMember(node: ?Object, opts?: Object): boolean {
+  if (!node) return false;
+
+  const nodeType = node.type;
+  if (nodeType === "TSNamedTupleMember") {
+    if (typeof opts === "undefined") {
+      return true;
+    } else {
+      return shallowEqual(node, opts);
+    }
+  }
+
+  return false;
+}
 export function isTSUnionType(node: ?Object, opts?: Object): boolean {
   if (!node) return false;