From eb085199b56f31576dc9ee63a2876a3ebdc958f4 Mon Sep 17 00:00:00 2001
From: Ivan Goncharov <ivan.goncharov.ua@gmail.com>
Date: Tue, 27 Aug 2019 15:52:39 +0300
Subject: [PATCH] Flow: fix errors in 'flatMap.js' on old Flow versions

Fixes #2136
---
 src/polyfills/flatMap.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/polyfills/flatMap.js b/src/polyfills/flatMap.js
index b2402dfa59..96c038d1c1 100644
--- a/src/polyfills/flatMap.js
+++ b/src/polyfills/flatMap.js
@@ -5,11 +5,14 @@ declare function flatMap<T, U>(
   fn: (item: T, index: number) => $ReadOnlyArray<U> | U,
 ): Array<U>;
 
+// Workaround to make older Flow versions happy
+const flatMapMethod = (Array.prototype: any).flatMap;
+
 /* eslint-disable no-redeclare */
 // $FlowFixMe
-const flatMap = Array.prototype.flatMap
+const flatMap = flatMapMethod
   ? function(list, fn) {
-      return Array.prototype.flatMap.call(list, fn);
+      return flatMapMethod.call(list, fn);
     }
   : function(list, fn) {
       let result = [];