Make StyleSheet modules Flow strict-local (#57731)

Summary:
Pull Request resolved: #57731

Upgrade the StyleSheet modules from `flow` to `flow strict-local`. `processFilter` and `setNormalizedColorAlpha` required small, behavior-preserving refactors (local variables instead of reassigning function parameters, and explicit null/empty checks) to satisfy the stricter lints.

Changelog: [Internal]

Reviewed By: javache

Differential Revision: D113763790

Author: rubennorte

packages/react-native/Libraries/StyleSheet/StyleSheet.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
  */
 

packages/react-native/Libraries/StyleSheet/StyleSheet.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
  */
 

packages/react-native/Libraries/StyleSheet/StyleSheetExports.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
  */
 
@@ -86,9 +86,9 @@ declare export const flatten: typeof flattenStyle;
  * internally to process color and transform values. You should not use this
  * unless you really know what you are doing and have exhausted other options.
  */
-declare export const setStyleAttributePreprocessor: (
+declare export const setStyleAttributePreprocessor: <T>(
   property: string,
-  process: (nextProp: any) => any,
+  process: (nextProp: T) => unknown,
 ) => void;
 
 /**

packages/react-native/Libraries/StyleSheet/processFilter.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 strict-local
  */
 
@@ -51,13 +51,13 @@ export default function processFilter(
   }
 
   if (typeof filter === 'string') {
-    filter = filter.replace(NEWLINE_REGEX, ' ');
+    const normalizedFilter = filter.replace(NEWLINE_REGEX, ' ');
 
     // matches on functions with args and nested functions like "drop-shadow(10 10 10 rgba(0, 0, 0, 1))"
     FILTER_FUNCTION_REGEX.lastIndex = 0;
     let matches;
 
-    while ((matches = FILTER_FUNCTION_REGEX.exec(filter))) {
+    while ((matches = FILTER_FUNCTION_REGEX.exec(normalizedFilter))) {
       let filterName = matches[1].toLowerCase();
       if (filterName === 'drop-shadow') {
         const dropShadow = parseDropShadow(matches[2]);
@@ -159,7 +159,7 @@ function _getFilterAmount(filterName: string, filterArgs: unknown): ?number {
     // blur takes any positive CSS length that is not a percent. In RN
     // we currently only have DIPs, so we are not parsing units here.
     case 'blur':
-      if ((unit && unit !== 'px') || filterArgAsNumber < 0) {
+      if ((Boolean(unit) && unit !== 'px') || filterArgAsNumber < 0) {
         return undefined;
       }
       return filterArgAsNumber;
@@ -173,7 +173,10 @@ function _getFilterAmount(filterName: string, filterArgs: unknown): ?number {
     case 'opacity':
     case 'saturate':
     case 'sepia':
-      if ((unit && unit !== '%' && unit !== 'px') || filterArgAsNumber < 0) {
+      if (
+        (Boolean(unit) && unit !== '%' && unit !== 'px') ||
+        filterArgAsNumber < 0
+      ) {
         return undefined;
       }
       if (unit === '%') {

packages/react-native/Libraries/StyleSheet/processTransformOrigin.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
  */
 
@@ -20,10 +20,11 @@ const INDEX_Z = 2;
 
 /* eslint-disable no-labels */
 export default function processTransformOrigin(
-  transformOrigin: Array<string | number> | string,
+  transformOriginInput: Array<string | number> | string,
 ): Array<string | number> {
-  if (typeof transformOrigin === 'string') {
-    const transformOriginString = transformOrigin;
+  let transformOrigin: Array<string | number>;
+  if (typeof transformOriginInput === 'string') {
+    const transformOriginString = transformOriginInput;
     TRANSFORM_ORIGIN_REGEX.lastIndex = 0;
     const transformOriginArray: Array<string | number> = ['50%', '50%', 0];
 
@@ -111,6 +112,8 @@ export default function processTransformOrigin(
     }
 
     transformOrigin = transformOriginArray;
+  } else {
+    transformOrigin = transformOriginInput;
   }
 
   if (__DEV__) {

packages/react-native/Libraries/StyleSheet/setNormalizedColorAlpha.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
  */
 
@@ -17,15 +17,16 @@
  * alpha should be number between 0 and 1
  */
 function setNormalizedColorAlpha(input: number, alpha: number): number {
-  if (alpha < 0) {
-    alpha = 0;
-  } else if (alpha > 1) {
-    alpha = 1;
+  let normalizedAlpha = alpha;
+  if (normalizedAlpha < 0) {
+    normalizedAlpha = 0;
+  } else if (normalizedAlpha > 1) {
+    normalizedAlpha = 1;
   }
 
-  alpha = Math.round(alpha * 255);
+  normalizedAlpha = Math.round(normalizedAlpha * 255);
   // magic bitshift guarantees we return an unsigned int
-  return ((input & 0xffffff00) | alpha) >>> 0;
+  return ((input & 0xffffff00) | normalizedAlpha) >>> 0;
 }
 
 export default setNormalizedColorAlpha;

packages/react-native/ReactNativeApi.d.ts

@@ -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.
  *
- * @generated SignedSource<<5391dae1ee6f722cdac0c6590bd19a44>>
+ * @generated SignedSource<<885d6e32c851ff6142ee176fe7adb996>>
  *
  * This file was generated by scripts/js-api/build-types/index.js.
  */
@@ -372,9 +372,9 @@ declare const sequence: typeof $$AnimatedImplementation.sequence
 declare const sequenceImpl: (
   animations: Array<CompositeAnimation>,
 ) => CompositeAnimation
-declare const setStyleAttributePreprocessor: (
+declare const setStyleAttributePreprocessor: <T>(
   property: string,
-  process: (nextProp: any) => any,
+  process: (nextProp: T) => unknown,
 ) => void
 declare const Settings: typeof Settings_default
 declare let Settings_default: {
@@ -5979,7 +5979,7 @@ export {
   StatusBarProps, // c2a44d88
   StatusBarStyle, // 78f53eea
   StyleProp, // fa0e9b4a
-  StyleSheet, // e2400c9e
+  StyleSheet, // 6a67f398
   SubmitBehavior, // c4ddf490
   Switch, // cf0d6ce5
   SwitchChangeEvent, // 899635b1