react · rubennorte · Sep 3, 2026 · Sep 3, 2026 · Sep 3, 2026 · Sep 3, 2026
diff --git a/packages/react-native/Libraries/Blob/File.js b/packages/react-native/Libraries/Blob/File.js
@@ -4,10 +4,12 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
+// flowlint unsafe-getters-setters:off
+
 'use strict';
 
 import type {BlobOptions} from './BlobTypes';

diff --git a/packages/react-native/Libraries/Blob/FileReader.js b/packages/react-native/Libraries/Blob/FileReader.js
@@ -4,10 +4,12 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
+// flowlint unsafe-getters-setters:off
+
 import type {EventCallback} from '../../src/private/webapis/dom/events/EventTarget';
 import type Blob from './Blob';
 

diff --git a/packages/react-native/Libraries/Blob/URL.js b/packages/react-native/Libraries/Blob/URL.js
@@ -4,10 +4,12 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
+// flowlint unsafe-getters-setters:off
+
 import type Blob from './Blob';
 
 import NativeBlobModule from './NativeBlobModule';
@@ -79,6 +81,7 @@ export class URL {
   // $FlowFixMe[missing-local-annot]
   constructor(url: string, base?: string | URL) {
     let baseUrl = null;
+    // $FlowFixMe[sketchy-null-string]
     if (!base || validateBaseUrl(url)) {
       this._url = url;
       if (this._url.includes('#')) {
@@ -112,13 +115,14 @@ export class URL {
       if (baseUrl.endsWith('/')) {
         baseUrl = baseUrl.slice(0, baseUrl.length - 1);
       }
-      if (!url.startsWith('/')) {
-        url = `/${url}`;
+      let path = url;
+      if (!path.startsWith('/')) {
+        path = `/${path}`;
       }
-      if (baseUrl.endsWith(url)) {
-        url = '';
+      if (baseUrl.endsWith(path)) {
+        path = '';
       }
-      this._url = `${baseUrl}${url}`;
+      this._url = `${baseUrl}${path}`;
     }
   }
 

diff --git a/packages/react-native/Libraries/Blob/URLSearchParams.js b/packages/react-native/Libraries/Blob/URLSearchParams.js
@@ -4,10 +4,12 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
+// flowlint unsafe-getters-setters:off
+
 // Small subset from whatwg-url: https://github.com/jsdom/whatwg-url/tree/master/src
 // The reference code bloat comes from Unicode issues with URLs, so those won't work here.
 export class URLSearchParams {

diff --git a/packages/react-native/Libraries/Blob/URLSearchParams.js.flow b/packages/react-native/Libraries/Blob/URLSearchParams.js.flow
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 

diff --git a/packages/react-native/Libraries/Components/ActivityIndicator/ActivityIndicator.js b/packages/react-native/Libraries/Components/ActivityIndicator/ActivityIndicator.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
@@ -115,7 +115,7 @@ const ActivityIndicator: component(
   style,
   ...restProps
 }: {
-  ref?: any,
+  ref?: React.RefSetter<ActivityIndicatorInstance>,
   ...ActivityIndicatorProps,
 }) => {
   let sizeStyle;

diff --git a/packages/react-native/Libraries/Components/Button.js b/packages/react-native/Libraries/Components/Button.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
@@ -232,7 +232,7 @@ const Button: component(
   } = props;
   const buttonStyles: Array<ViewStyleProp> = [styles.button];
   const textStyles: Array<TextStyleProp> = [styles.text];
-  if (color) {
+  if (Boolean(color)) {
     if (Platform.OS === 'ios') {
       textStyles.push({color: color});
     } else {
@@ -256,7 +256,7 @@ const Button: component(
       ? {..._accessibilityState, disabled}
       : _accessibilityState;
 
-  if (disabled) {
+  if (disabled === true) {
     buttonStyles.push(styles.buttonDisabled);
     textStyles.push(styles.textDisabled);
   }
@@ -279,7 +279,10 @@ const Button: component(
       accessible={accessible}
       accessibilityActions={accessibilityActions}
       onAccessibilityAction={onAccessibilityAction}
-      accessibilityLabel={ariaLabel || accessibilityLabel}
+      accessibilityLabel={
+        // $FlowFixMe[sketchy-null-string]
+        ariaLabel || accessibilityLabel
+      }
       accessibilityHint={accessibilityHint}
       accessibilityLanguage={accessibilityLanguage}
       accessibilityRole="button"

diff --git a/packages/react-native/Libraries/Components/DrawerAndroid/DrawerLayoutAndroid.android.js b/packages/react-native/Libraries/Components/DrawerAndroid/DrawerLayoutAndroid.android.js
@@ -4,10 +4,12 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
+// flowlint unsafe-getters-setters:off
+
 import type {
   MeasureInWindowOnSuccessCallback,
   MeasureLayoutOnSuccessCallback,
@@ -204,7 +206,7 @@ class DrawerLayoutAndroid
     );
   }
 
-  setNativeProps(nativeProps: Object) {
+  setNativeProps(nativeProps: {...}) {
     nullthrows(this._nativeRef.current).setNativeProps(nativeProps);
   }
 }

diff --git a/packages/react-native/Libraries/Components/DrawerAndroid/DrawerLayoutAndroid.js b/packages/react-native/Libraries/Components/DrawerAndroid/DrawerLayoutAndroid.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 

diff --git a/packages/react-native/Libraries/Components/DrawerAndroid/DrawerLayoutAndroidTypes.js b/packages/react-native/Libraries/Components/DrawerAndroid/DrawerLayoutAndroidTypes.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
@@ -127,7 +127,7 @@ export interface DrawerLayoutAndroidMethods {
     onSuccess: MeasureLayoutOnSuccessCallback,
     onFail?: () => void,
   ): void;
-  setNativeProps(nativeProps: Object): void;
+  setNativeProps(nativeProps: {...}): void;
 }
 
 export type DrawerLayoutAndroidInstance = DrawerLayoutAndroidMethods;
diff --git a/packages/react-native/Libraries/Components/StatusBar/StatusBar.js b/packages/react-native/Libraries/Components/StatusBar/StatusBar.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
@@ -101,13 +101,25 @@ export type StatusBarProps = Readonly<{
 
 type StackProps = {
   barStyle: ?{
-    value: StatusBarProps['barStyle'],
+    value: StatusBarStyle,
     animated: boolean,
   },
   hidden: ?{
     value: boolean,
     animated: boolean,
-    transition: StatusBarProps['showHideTransition'],
+    transition: StatusBarAnimation,
+  },
+};
+
+type ResolvedStackProps = {
+  barStyle: {
+    value: StatusBarStyle,
+    animated: boolean,
+  },
+  hidden: {
+    value: boolean,
+    animated: boolean,
+    transition: StatusBarAnimation,
   },
 };
 
@@ -126,13 +138,16 @@ function getAutoBarStyle(): 'light-content' | 'dark-content' {
  * barStyle to a concrete value.
  */
 function mergePropsStack(
-  propsStack: Array<Object>,
-  defaultValues: Object,
-): Object {
-  const merged: StackProps = propsStack.reduce(
+  propsStack: Array<StackProps>,
+  defaultValues: ResolvedStackProps,
+): ResolvedStackProps {
+  const merged: ResolvedStackProps = propsStack.reduce(
     (prev, cur) => {
       for (const prop in cur) {
+        // $FlowFixMe[invalid-computed-prop] dynamic merge over the known StackProps keys
         if (cur[prop] != null) {
+          // $FlowFixMe[invalid-computed-prop] dynamic merge over the known StackProps keys
+          // $FlowFixMe[prop-missing] dynamic merge over the known StackProps keys
           prev[prop] = cur[prop];
         }
       }
@@ -141,7 +156,7 @@ function mergePropsStack(
     {...defaultValues},
   );
 
-  if (merged.barStyle?.value === 'auto') {
+  if (merged.barStyle.value === 'auto') {
     merged.barStyle = {...merged.barStyle, value: getAutoBarStyle()};
   }
 
@@ -224,18 +239,18 @@ function createStackEntry(props: StatusBarProps): StackProps {
 class StatusBar extends React.Component<StatusBarProps> {
   static _propsStack: Array<StackProps> = [];
 
-  static _defaultProps: any = createStackEntry({
-    barStyle: 'default',
-    hidden: false,
-  });
+  static _defaultProps: ResolvedStackProps = {
+    barStyle: {value: 'default', animated: false},
+    hidden: {value: false, animated: false, transition: 'fade'},
+  };
 
   // Timer for updating the native module values at the end of the frame.
   static _updateImmediate: ?number = null;
 
   // The current merged values from the props stack. `barStyle.value` is stored
   // in its resolved form (never `'auto'`), so diff comparisons reflect what
   // was actually sent to the native module.
-  static _currentValues: ?StackProps = null;
+  static _currentValues: ?ResolvedStackProps = null;
 
   // Number of mounted `StatusBar` instances. Used to lazily subscribe to color
   // scheme changes only while at least one instance is on screen.
@@ -264,10 +279,10 @@ class StatusBar extends React.Component<StatusBarProps> {
    *    changing the status bar hidden property.
    */
   static setHidden(hidden: boolean, animation?: StatusBarAnimation) {
-    animation = animation || 'none';
+    const resolvedAnimation = animation ?? 'none';
     StatusBar._defaultProps.hidden.value = hidden;
     if (Platform.OS === 'ios') {
-      NativeStatusBarManagerIOS.setHidden(hidden, animation);
+      NativeStatusBarManagerIOS.setHidden(hidden, resolvedAnimation);
     } else if (Platform.OS === 'android') {
       NativeStatusBarManagerAndroid.setHidden(hidden);
     }
@@ -279,11 +294,11 @@ class StatusBar extends React.Component<StatusBarProps> {
    * @param animated Animate the style change.
    */
   static setBarStyle(style: StatusBarStyle, animated?: boolean) {
-    animated = animated || false;
+    const resolvedAnimated = animated ?? false;
     StatusBar._defaultProps.barStyle.value = style;
     const resolvedStyle = style === 'auto' ? getAutoBarStyle() : style;
     if (Platform.OS === 'ios') {
-      NativeStatusBarManagerIOS.setStyle(resolvedStyle, animated);
+      NativeStatusBarManagerIOS.setStyle(resolvedStyle, resolvedAnimated);
     } else if (Platform.OS === 'android') {
       NativeStatusBarManagerAndroid.setStyle(resolvedStyle);
     }

diff --git a/packages/react-native/Libraries/Components/Touchable/Touchable.js b/packages/react-native/Libraries/Components/Touchable/Touchable.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  */
 
@@ -331,7 +331,7 @@ const TouchableMixinImpl = {
    */
   /* $FlowFixMe[missing-this-annot] The 'this' type annotation(s) required by
    * Flow's LTI update could not be added via codemod */
-  touchableHandleResponderTerminationRequest: function (): any {
+  touchableHandleResponderTerminationRequest: function (): boolean {
     return !this.props.rejectResponderTermination;
   },
 
@@ -340,7 +340,7 @@ const TouchableMixinImpl = {
    */
   /* $FlowFixMe[missing-this-annot] The 'this' type annotation(s) required by
    * Flow's LTI update could not be added via codemod */
-  touchableHandleStartShouldSetResponder: function (): any {
+  touchableHandleStartShouldSetResponder: function (): boolean {
     return !this.props.disabled;
   },
 

diff --git a/packages/react-native/Libraries/Core/Timers/immediateShim.js b/packages/react-native/Libraries/Core/Timers/immediateShim.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
+ * @flow strict-local
  * @format
  * @deprecated
  */
@@ -22,7 +22,10 @@ const clearedImmediates: Set<number> = new Set();
  * @param {function} func Callback to be invoked before the end of the
  * current JavaScript execution loop.
  */
-export function setImmediate(callback: Function, ...args: any): number {
+export function setImmediate<TArgs extends Array<unknown>>(
+  callback: (...args: TArgs) => unknown,
+  ...args: TArgs
+): number {
   if (arguments.length < 1) {
     throw new TypeError(
       'setImmediate must be called with at least one argument (a function to call)',
@@ -41,7 +44,6 @@ export function setImmediate(callback: Function, ...args: any): number {
     clearedImmediates.delete(id);
   }
 
-  // $FlowFixMe[incompatible-type]
   global.queueMicrotask(() => {
     if (!clearedImmediates.has(id)) {
       callback.apply(undefined, args);