[RootRef] Remove component

.eslintrc.js

@@ -102,8 +102,6 @@ module.exports = {
     'react/no-array-index-key': 'off',
     'react/no-danger': 'error',
     'react/no-direct-mutation-state': 'error',
-    // Required for backward compatibility. TODO v5, drop
-    'react/no-find-dom-node': 'off',
     // Not always relevant
     'react/require-default-props': 'off',
     'react/sort-prop-types': 'error',

docs/src/pages/guides/migration-v4/migration-v4.md

@@ -110,6 +110,19 @@ This change affects almost all components where you're using the `component` pro
   />
   ```
 
+### RootRef
+
+- This component was removed.
+  You can get a reference to the underlying DOM node of our components via `ref` prop.
+  The component relied on [`ReactDOM.findDOMNode`](https://reactjs.org/docs/react-dom.html#finddomnode) which is [deprecated in `React.StrictMode`](https://reactjs.org/docs/strict-mode.html#warning-about-deprecated-finddomnode-usage).
+
+  ```diff
+  -<RootRef rootRef={ref}>
+  -  <Button />
+  -</RootRef>
+  +<Button ref={ref} />
+  ```
+
 ### Slider
 
 - typescript: The `event` in `onChange` is no longer typed as a `React.ChangeEvent` but `React.SyntheticEvent`.

packages/material-ui/src/index.d.ts

@@ -294,9 +294,6 @@ export * from './Radio';
 export { default as RadioGroup } from './RadioGroup';
 export * from './RadioGroup';
 
-export { default as RootRef } from './RootRef';
-export * from './RootRef';
-
 export { default as ScopedCssBaseline } from './ScopedCssBaseline';
 export * from './ScopedCssBaseline';
 

packages/material-ui/src/index.js

@@ -240,9 +240,6 @@ export * from './Radio';
 export { default as RadioGroup } from './RadioGroup';
 export * from './RadioGroup';
 
-export { default as RootRef } from './RootRef';
-export * from './RootRef';
-
 export { default as ScopedCssBaseline } from './ScopedCssBaseline';
 export * from './ScopedCssBaseline';