From 02ff115ce9fdf39cf1ff998c761515b9acc79d42 Mon Sep 17 00:00:00 2001
From: Diogo Franco <diogomfranco@gmail.com>
Date: Wed, 4 Apr 2018 14:10:25 +0900
Subject: [PATCH] [react] Workaround for --strictFunctionTypes (#24709)

* [react] Workaround for --strictFunctionTypes

Under --strictFunctionTypes, when assigning a class with `getDerivedStateFromProps` to `React.ComponentClass` or `React.ComponentType`, the type of the second argument was expected to be `Readonly<any>`, which is, actually, the same as `Readonly<{}>`.

This was preventing using classes that try to refer to the previous state in `getDerivedStateFromProps` from being given to HOC factories.

There are no tests as testing this change is only possible with `--strictFunctionTypes`, and the `tsconfig.json` here specifically disables it. Perhaps another PR should enable it.

* Add a test anyway

Though it wouldn't have failed unless `--strictFunctionTypes` were enabled.

* Fix lint error on the test
---
 types/react/index.d.ts   | 2 +-
 types/react/test/tsx.tsx | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/types/react/index.d.ts b/types/react/index.d.ts
index 49224d93cf..2ed2fb497c 100644
--- a/types/react/index.d.ts
+++ b/types/react/index.d.ts
@@ -404,7 +404,7 @@ declare namespace React {
          *
          * Note: its presence prevents any of the deprecated lifecycle methods from being invoked
          */
-        (nextProps: Readonly<P>, prevState: Readonly<S>) => Partial<S> | null;
+        (nextProps: Readonly<P>, prevState: S) => Partial<S> | null;
 
     // This should be "infer SS" but can't use it yet
     interface NewLifecycle<P, S, SS> {
diff --git a/types/react/test/tsx.tsx b/types/react/test/tsx.tsx
index b086e35f9f..760a625cfd 100644
--- a/types/react/test/tsx.tsx
+++ b/types/react/test/tsx.tsx
@@ -156,6 +156,7 @@ class ComponentWithLargeState extends React.Component<{}, Record<'a'|'b'|'c', st
         return { a: 'a' };
     }
 }
+const AssignedComponentWithLargeState: React.ComponentClass = ComponentWithLargeState;
 
 const componentWithBadLifecycle = new (class extends React.Component<{}, {}, number> {})({});
 componentWithBadLifecycle.getSnapshotBeforeUpdate = () => { // $ExpectError