From 46d6766a53f6fa7550ad4dd34bcb97549e716ef7 Mon Sep 17 00:00:00 2001
From: Spencer Ahrens <sahrens@fb.com>
Date: Tue, 21 Mar 2017 22:19:13 -0700
Subject: [PATCH] useful error when switching numColumns on the fly

Reviewed By: blairvanderhoof, bvaughn

Differential Revision: D4742842

fbshipit-source-id: a11a088194ead02cc11eb6ccd9ce6d6f75ead3a3
---
 Libraries/CustomComponents/Lists/FlatList.js | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Libraries/CustomComponents/Lists/FlatList.js b/Libraries/CustomComponents/Lists/FlatList.js
index 2f7bd153638..77ca170845c 100644
--- a/Libraries/CustomComponents/Lists/FlatList.js
+++ b/Libraries/CustomComponents/Lists/FlatList.js
@@ -242,6 +242,11 @@ class FlatList<ItemT> extends React.PureComponent<DefaultProps, Props<ItemT>, vo
   }
 
   componentWillReceiveProps(nextProps: Props<ItemT>) {
+    invariant(
+      nextProps.numColumns === this.props.numColumns,
+      'Changing numColumns on the fly is not supported. Change the key prop on FlatList when ' +
+      'changing the number of columns to force a fresh render of the component.'
+    );
     this._checkProps(nextProps);
   }