From d82681bcf69ccc544dbb8c449f8be08305bd67a1 Mon Sep 17 00:00:00 2001
From: Sam Goldman <samwgoldman@gmail.com>
Date: Fri, 14 Oct 2016 12:16:02 -0700
Subject: [PATCH] Add EmptyTypeAnnotation (#4724)

Added to Flow in facebook/flow#c603505583993aa953904005f91c350f4b65d6bd
Parser support added in babel/babylon#171.
---
 packages/babel-generator/src/generators/flow.js     | 4 ++++
 packages/babel-traverse/src/path/inference/index.js | 2 ++
 packages/babel-types/README.md                      | 5 +++++
 packages/babel-types/src/definitions/flow.js        | 4 ++++
 4 files changed, 15 insertions(+)

diff --git a/packages/babel-generator/src/generators/flow.js b/packages/babel-generator/src/generators/flow.js
index 57a9aedc9cd63..4a2b8ff0f6cc1 100644
--- a/packages/babel-generator/src/generators/flow.js
+++ b/packages/babel-generator/src/generators/flow.js
@@ -167,6 +167,10 @@ export function MixedTypeAnnotation() {
   this.word("mixed");
 }
 
+export function EmptyTypeAnnotation() {
+  this.word("empty");
+}
+
 export function NullableTypeAnnotation(node: Object) {
   this.token("?");
   this.print(node.typeAnnotation, node);
diff --git a/packages/babel-traverse/src/path/inference/index.js b/packages/babel-traverse/src/path/inference/index.js
index d6b9c878f3372..55a52911a655a 100644
--- a/packages/babel-traverse/src/path/inference/index.js
+++ b/packages/babel-traverse/src/path/inference/index.js
@@ -73,6 +73,8 @@ function _isBaseType(baseName: string, type?, soft?): boolean {
     return t.isAnyTypeAnnotation(type);
   } else if (baseName === "mixed") {
     return t.isMixedTypeAnnotation(type);
+  } else if (baseName === "empty") {
+    return t.isEmptyTypeAnnotation(type);
   } else if (baseName === "void") {
     return t.isVoidTypeAnnotation(type);
   } else {
diff --git a/packages/babel-types/README.md b/packages/babel-types/README.md
index a8dc4f2728053..884aae17d6eac 100644
--- a/packages/babel-types/README.md
+++ b/packages/babel-types/README.md
@@ -755,6 +755,11 @@ See also `t.isMixedTypeAnnotation(node, opts)` and `t.assertMixedTypeAnnotation(
 
 Aliases: `Flow`, `FlowBaseAnnotation`
 
+### t.emptyTypeAnnotation()
+
+See also `t.isEmptyTypeAnnotation(node, opts)` and `t.assertEmptyTypeAnnotation(node, opts)`.
+
+Aliases: `Flow`, `FlowBaseAnnotation`
 
 ### t.newExpression(callee, arguments)
 
diff --git a/packages/babel-types/src/definitions/flow.js b/packages/babel-types/src/definitions/flow.js
index 0a8a965e40420..308defb12fee6 100644
--- a/packages/babel-types/src/definitions/flow.js
+++ b/packages/babel-types/src/definitions/flow.js
@@ -167,6 +167,10 @@ defineType("MixedTypeAnnotation", {
   aliases: ["Flow", "FlowBaseAnnotation"]
 });
 
+defineType("EmptyTypeAnnotation", {
+  aliases: ["Flow", "FlowBaseAnnotation"]
+});
+
 defineType("NullableTypeAnnotation", {
   visitor: ["typeAnnotation"],
   aliases: ["Flow"],