From ca3bf7f06d894d2bdc3e89a4eccaf463dfe68815 Mon Sep 17 00:00:00 2001
From: Frank Tan <tansongyang@gmail.com>
Date: Sat, 14 Apr 2018 12:09:19 -0700
Subject: [PATCH] Re-type `helper` from `@ember/component/helper` (#24986)

* Re-type `helper` from @ember/component/helper

Previous typing caused an error about using private name `Ember.Helper`
when generating declaration files.

Fortunately, the previous typings were incorrect anyway, so we can
remove the reference to `Ember.Helper` and thus fix the issue.

Relevant links:
* https://github.com/Microsoft/TypeScript/issues/5711
* https://github.com/Microsoft/TypeScript/issues/6307
* https://www.emberjs.com/api/ember/2.18/functions/@ember%2Fcomponent%2Fhelper/helper
* https://github.com/emberjs/ember.js/blob/v2.18.2/packages/ember-glimmer/lib/helper.ts#L120

* Add test for `helper` from @ember/component/helper
---
 types/ember/index.d.ts     | 15 ++++++++++++++-
 types/ember/test/helper.ts |  8 ++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/types/ember/index.d.ts b/types/ember/index.d.ts
index 740ff1308c..c825647e49 100755
--- a/types/ember/index.d.ts
+++ b/types/ember/index.d.ts
@@ -3442,7 +3442,20 @@ declare module '@ember/component/checkbox' {
 declare module '@ember/component/helper' {
     import Ember from 'ember';
     export default class Helper extends Ember.Helper { }
-    export const helper: typeof Ember.Helper.helper;
+    /**
+     * In many cases, the ceremony of a full `Helper` class is not required.
+     * The `helper` method create pure-function helpers without instances. For
+     * example:
+     * ```app/helpers/format-currency.js
+     * import { helper } from '@ember/component/helper';
+     * export default helper(function(params, hash) {
+     *   let cents = params[0];
+     *   let currency = hash.currency;
+     *   return `${currency}${cents * 0.01}`;
+     * });
+     * ```
+     */
+    export function helper(helperFn: (params: any[], hash?: any) => string): any;
 }
 
 declare module '@ember/component/text-area' {
diff --git a/types/ember/test/helper.ts b/types/ember/test/helper.ts
index efe3ce33d7..cba5709b10 100755
--- a/types/ember/test/helper.ts
+++ b/types/ember/test/helper.ts
@@ -25,3 +25,11 @@ const CurrentUserEmailHelper = Ember.Helper.extend({
             .get('email');
     },
 });
+
+import { helper } from '@ember/component/helper';
+
+function typedHelp(/*params, hash*/) {
+  return 'my type of help';
+}
+
+export default helper(typedHelp);