Use Flow in feature flags scripts (#42814)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/42814

Improves the type safety of the feature flags generation and verification script.

Changelog: [internal]

Reviewed By: huntie

Differential Revision: D53351484

fbshipit-source-id: a71af1bb428cdec327d557de4d54bee9ece57f34

flow-typed/npm/signedsource_v1.x.x.js

@@ -0,0 +1,19 @@
+/**
+ * (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+ *
+ * @format
+ * @flow strict
+ */
+
+declare module 'signedsource' {
+  declare type SignedSource = {
+    TokenNotFoundError: Error,
+    getSigningToken(): string,
+    isSigned(data: string): boolean,
+    signFile(data: string): string,
+    verifySignature(data: string): boolean,
+    [key: string]: mixed,
+  };
+
+  declare module.exports: SignedSource;
+}

packages/react-native/package.json

@@ -90,8 +90,8 @@
   ],
   "scripts": {
     "prepack": "cp ../../README.md .",
-    "featureflags-check": "node ./scripts/featureflags/update.js --verify-unchanged",
-    "featureflags-update": "node ./scripts/featureflags/update.js"
+    "featureflags-check": "node ./scripts/featureflags/index.js --verify-unchanged",
+    "featureflags-update": "node ./scripts/featureflags/index.js"
   },
   "peerDependencies": {
     "react": "18.2.0"

packages/react-native/scripts/featureflags/README.md

@@ -47,7 +47,8 @@ Example:
 ```
 
 After any changes to this definitions, the code that provides access to them
-must be regenerated executing the `update` script in this directory.
+must be regenerated running `yarn featureflags-update` from the `react-native`
+repository.
 
 ## Access
 

packages/react-native/scripts/featureflags/generateAndroidModules.js

@@ -4,65 +4,49 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {GeneratorConfig, GeneratorResult} from './types';
 
-const JReactNativeFeatureFlagsCxxInteropCPP = require('./templates/android/JReactNativeFeatureFlagsCxxInterop.cpp-template');
-const JReactNativeFeatureFlagsCxxInteropH = require('./templates/android/JReactNativeFeatureFlagsCxxInterop.h-template');
-const ReactNativeFeatureFlagsKt = require('./templates/android/ReactNativeFeatureFlags.kt-template');
-const ReactNativeFeatureFlagsCxxAccessorKt = require('./templates/android/ReactNativeFeatureFlagsCxxAccessor.kt-template');
-const ReactNativeFeatureFlagsCxxInteropKt = require('./templates/android/ReactNativeFeatureFlagsCxxInterop.kt-template');
-const ReactNativeFeatureFlagsDefaultsKt = require('./templates/android/ReactNativeFeatureFlagsDefaults.kt-template');
-const ReactNativeFeatureFlagsLocalAccessorKt = require('./templates/android/ReactNativeFeatureFlagsLocalAccessor.kt-template');
-const ReactNativeFeatureFlagsProviderKt = require('./templates/android/ReactNativeFeatureFlagsProvider.kt-template');
-const ReactNativeFeatureFlagsProviderHolderCPP = require('./templates/android/ReactNativeFeatureFlagsProviderHolder.cpp-template');
-const ReactNativeFeatureFlagsProviderHolderH = require('./templates/android/ReactNativeFeatureFlagsProviderHolder.h-template');
-const path = require('path');
+import JReactNativeFeatureFlagsCxxInteropCPP from './templates/android/JReactNativeFeatureFlagsCxxInterop.cpp-template';
+import JReactNativeFeatureFlagsCxxInteropH from './templates/android/JReactNativeFeatureFlagsCxxInterop.h-template';
+import ReactNativeFeatureFlagsKt from './templates/android/ReactNativeFeatureFlags.kt-template';
+import ReactNativeFeatureFlagsCxxAccessorKt from './templates/android/ReactNativeFeatureFlagsCxxAccessor.kt-template';
+import ReactNativeFeatureFlagsCxxInteropKt from './templates/android/ReactNativeFeatureFlagsCxxInterop.kt-template';
+import ReactNativeFeatureFlagsDefaultsKt from './templates/android/ReactNativeFeatureFlagsDefaults.kt-template';
+import ReactNativeFeatureFlagsLocalAccessorKt from './templates/android/ReactNativeFeatureFlagsLocalAccessor.kt-template';
+import ReactNativeFeatureFlagsProviderKt from './templates/android/ReactNativeFeatureFlagsProvider.kt-template';
+import ReactNativeFeatureFlagsProviderHolderCPP from './templates/android/ReactNativeFeatureFlagsProviderHolder.cpp-template';
+import ReactNativeFeatureFlagsProviderHolderH from './templates/android/ReactNativeFeatureFlagsProviderHolder.h-template';
+import path from 'path';
+
+export default function generateAndroidModules(
+  generatorConfig: GeneratorConfig,
+): GeneratorResult {
+  const {androidPath, androidJniPath, featureFlagDefinitions} = generatorConfig;
 
-module.exports = function generateandroidModules(
-  generatorConfig,
-  featureFlagsConfig,
-) {
   return {
-    [path.join(generatorConfig.androidPath, 'ReactNativeFeatureFlags.kt')]:
-      ReactNativeFeatureFlagsKt(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidPath,
-      'ReactNativeFeatureFlagsCxxAccessor.kt',
-    )]: ReactNativeFeatureFlagsCxxAccessorKt(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidPath,
-      'ReactNativeFeatureFlagsLocalAccessor.kt',
-    )]: ReactNativeFeatureFlagsLocalAccessorKt(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidPath,
-      'ReactNativeFeatureFlagsCxxInterop.kt',
-    )]: ReactNativeFeatureFlagsCxxInteropKt(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidPath,
-      'ReactNativeFeatureFlagsDefaults.kt',
-    )]: ReactNativeFeatureFlagsDefaultsKt(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidPath,
-      'ReactNativeFeatureFlagsProvider.kt',
-    )]: ReactNativeFeatureFlagsProviderKt(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidJniPath,
-      'ReactNativeFeatureFlagsProviderHolder.h',
-    )]: ReactNativeFeatureFlagsProviderHolderH(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidJniPath,
-      'ReactNativeFeatureFlagsProviderHolder.cpp',
-    )]: ReactNativeFeatureFlagsProviderHolderCPP(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidJniPath,
-      'JReactNativeFeatureFlagsCxxInterop.h',
-    )]: JReactNativeFeatureFlagsCxxInteropH(featureFlagsConfig),
-    [path.join(
-      generatorConfig.androidJniPath,
-      'JReactNativeFeatureFlagsCxxInterop.cpp',
-    )]: JReactNativeFeatureFlagsCxxInteropCPP(featureFlagsConfig),
+    [path.join(androidPath, 'ReactNativeFeatureFlags.kt')]:
+      ReactNativeFeatureFlagsKt(featureFlagDefinitions),
+    [path.join(androidPath, 'ReactNativeFeatureFlagsCxxAccessor.kt')]:
+      ReactNativeFeatureFlagsCxxAccessorKt(featureFlagDefinitions),
+    [path.join(androidPath, 'ReactNativeFeatureFlagsLocalAccessor.kt')]:
+      ReactNativeFeatureFlagsLocalAccessorKt(featureFlagDefinitions),
+    [path.join(androidPath, 'ReactNativeFeatureFlagsCxxInterop.kt')]:
+      ReactNativeFeatureFlagsCxxInteropKt(featureFlagDefinitions),
+    [path.join(androidPath, 'ReactNativeFeatureFlagsDefaults.kt')]:
+      ReactNativeFeatureFlagsDefaultsKt(featureFlagDefinitions),
+    [path.join(androidPath, 'ReactNativeFeatureFlagsProvider.kt')]:
+      ReactNativeFeatureFlagsProviderKt(featureFlagDefinitions),
+    [path.join(androidJniPath, 'ReactNativeFeatureFlagsProviderHolder.h')]:
+      ReactNativeFeatureFlagsProviderHolderH(featureFlagDefinitions),
+    [path.join(androidJniPath, 'ReactNativeFeatureFlagsProviderHolder.cpp')]:
+      ReactNativeFeatureFlagsProviderHolderCPP(featureFlagDefinitions),
+    [path.join(androidJniPath, 'JReactNativeFeatureFlagsCxxInterop.h')]:
+      JReactNativeFeatureFlagsCxxInteropH(featureFlagDefinitions),
+    [path.join(androidJniPath, 'JReactNativeFeatureFlagsCxxInterop.cpp')]:
+      JReactNativeFeatureFlagsCxxInteropCPP(featureFlagDefinitions),
   };
-};
+}

packages/react-native/scripts/featureflags/generateCommonCxxModules.js

@@ -4,43 +4,37 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {GeneratorConfig, GeneratorResult} from './types';
 
-const ReactNativeFeatureFlagsCPP = require('./templates/common-cxx/ReactNativeFeatureFlags.cpp-template');
-const ReactNativeFeatureFlagsH = require('./templates/common-cxx/ReactNativeFeatureFlags.h-template');
-const ReactNativeFeatureFlagsAccessorCPP = require('./templates/common-cxx/ReactNativeFeatureFlagsAccessor.cpp-template');
-const ReactNativeFeatureFlagsAccessorH = require('./templates/common-cxx/ReactNativeFeatureFlagsAccessor.h-template');
-const ReactNativeFeatureFlagsDefaultsH = require('./templates/common-cxx/ReactNativeFeatureFlagsDefaults.h-template');
-const ReactNativeFeatureFlagsProviderH = require('./templates/common-cxx/ReactNativeFeatureFlagsProvider.h-template');
-const path = require('path');
+import ReactNativeFeatureFlagsCPP from './templates/common-cxx/ReactNativeFeatureFlags.cpp-template';
+import ReactNativeFeatureFlagsH from './templates/common-cxx/ReactNativeFeatureFlags.h-template';
+import ReactNativeFeatureFlagsAccessorCPP from './templates/common-cxx/ReactNativeFeatureFlagsAccessor.cpp-template';
+import ReactNativeFeatureFlagsAccessorH from './templates/common-cxx/ReactNativeFeatureFlagsAccessor.h-template';
+import ReactNativeFeatureFlagsDefaultsH from './templates/common-cxx/ReactNativeFeatureFlagsDefaults.h-template';
+import ReactNativeFeatureFlagsProviderH from './templates/common-cxx/ReactNativeFeatureFlagsProvider.h-template';
+import path from 'path';
+
+export default function generateCommonCxxModules(
+  generatorConfig: GeneratorConfig,
+): GeneratorResult {
+  const {commonCxxPath, featureFlagDefinitions} = generatorConfig;
 
-module.exports = function generateCommonCxxModules(
-  generatorConfig,
-  featureFlagsConfig,
-) {
   return {
-    [path.join(generatorConfig.commonCxxPath, 'ReactNativeFeatureFlags.h')]:
-      ReactNativeFeatureFlagsH(featureFlagsConfig),
-    [path.join(generatorConfig.commonCxxPath, 'ReactNativeFeatureFlags.cpp')]:
-      ReactNativeFeatureFlagsCPP(featureFlagsConfig),
-    [path.join(
-      generatorConfig.commonCxxPath,
-      'ReactNativeFeatureFlagsAccessor.h',
-    )]: ReactNativeFeatureFlagsAccessorH(featureFlagsConfig),
-    [path.join(
-      generatorConfig.commonCxxPath,
-      'ReactNativeFeatureFlagsAccessor.cpp',
-    )]: ReactNativeFeatureFlagsAccessorCPP(featureFlagsConfig),
-    [path.join(
-      generatorConfig.commonCxxPath,
-      'ReactNativeFeatureFlagsDefaults.h',
-    )]: ReactNativeFeatureFlagsDefaultsH(featureFlagsConfig),
-    [path.join(
-      generatorConfig.commonCxxPath,
-      'ReactNativeFeatureFlagsProvider.h',
-    )]: ReactNativeFeatureFlagsProviderH(featureFlagsConfig),
+    [path.join(commonCxxPath, 'ReactNativeFeatureFlags.h')]:
+      ReactNativeFeatureFlagsH(featureFlagDefinitions),
+    [path.join(commonCxxPath, 'ReactNativeFeatureFlags.cpp')]:
+      ReactNativeFeatureFlagsCPP(featureFlagDefinitions),
+    [path.join(commonCxxPath, 'ReactNativeFeatureFlagsAccessor.h')]:
+      ReactNativeFeatureFlagsAccessorH(featureFlagDefinitions),
+    [path.join(commonCxxPath, 'ReactNativeFeatureFlagsAccessor.cpp')]:
+      ReactNativeFeatureFlagsAccessorCPP(featureFlagDefinitions),
+    [path.join(commonCxxPath, 'ReactNativeFeatureFlagsDefaults.h')]:
+      ReactNativeFeatureFlagsDefaultsH(featureFlagDefinitions),
+    [path.join(commonCxxPath, 'ReactNativeFeatureFlagsProvider.h')]:
+      ReactNativeFeatureFlagsProviderH(featureFlagDefinitions),
   };
-};
+}

packages/react-native/scripts/featureflags/generateFiles.js

@@ -4,49 +4,37 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-const generateAndroidModules = require('./generateAndroidModules');
-const generateCommonCxxModules = require('./generateCommonCxxModules');
-const generateJavaScriptModules = require('./generateJavaScriptModules');
-const fs = require('fs');
+import type {GeneratorConfig, GeneratorOptions} from './types';
 
-module.exports = function generateFiles(generatorConfig, generatorOptions) {
-  const userDefinedFeatureFlagsConfig = JSON.parse(
-    fs.readFileSync(generatorConfig.configPath, 'utf8'),
-  );
-
-  const featureFlagsConfig = Object.assign(
-    {jsOnly: {}, common: {}},
-    userDefinedFeatureFlagsConfig,
-  );
+import generateAndroidModules from './generateAndroidModules';
+import generateCommonCxxModules from './generateCommonCxxModules';
+import generateJavaScriptModules from './generateJavaScriptModules';
+import fs from 'fs';
 
+export default function generateFiles(
+  generatorConfig: GeneratorConfig,
+  generatorOptions: GeneratorOptions,
+): void {
   fs.mkdirSync(generatorConfig.jsPath, {recursive: true});
   fs.mkdirSync(generatorConfig.commonCxxPath, {recursive: true});
   fs.mkdirSync(generatorConfig.commonNativeModuleCxxPath, {recursive: true});
   fs.mkdirSync(generatorConfig.androidPath, {recursive: true});
   fs.mkdirSync(generatorConfig.androidJniPath, {recursive: true});
 
-  const jsModules = generateJavaScriptModules(
-    generatorConfig,
-    featureFlagsConfig,
-  );
+  const jsModules = generateJavaScriptModules(generatorConfig);
 
-  const commonCxxModules = generateCommonCxxModules(
-    generatorConfig,
-    featureFlagsConfig,
-  );
+  const commonCxxModules = generateCommonCxxModules(generatorConfig);
 
-  const androidModules = generateAndroidModules(
-    generatorConfig,
-    featureFlagsConfig,
-  );
+  const androidModules = generateAndroidModules(generatorConfig);
 
   const generatedFiles = {...jsModules, ...commonCxxModules, ...androidModules};
 
   if (generatorOptions.verifyUnchanged) {
-    const existingModules = {};
+    const existingModules: {[string]: string} = {};
     for (const moduleName of Object.keys(generatedFiles)) {
       const existingModule = fs.readFileSync(moduleName, 'utf8');
       existingModules[moduleName] = existingModule;
@@ -79,4 +67,4 @@ module.exports = function generateFiles(generatorConfig, generatorOptions) {
   for (const [modulePath, moduleContents] of Object.entries(generatedFiles)) {
     fs.writeFileSync(modulePath, moduleContents, 'utf8');
   }
-};
+}

packages/react-native/scripts/featureflags/generateJavaScriptModules.js

@@ -4,33 +4,32 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {GeneratorConfig, GeneratorResult} from './types';
 
-const NativeReactNativeFeatureFlagsCPP = require('./templates/js/NativeReactNativeFeatureFlags.cpp-template');
-const NativeReactNativeFeatureFlagsH = require('./templates/js/NativeReactNativeFeatureFlags.h-template');
-const NativeReactNativeFeatureFlagsJS = require('./templates/js/NativeReactNativeFeatureFlags.js-template');
-const ReactNativeFeatureFlagsJS = require('./templates/js/ReactNativeFeatureFlags.js-template');
-const path = require('path');
+import NativeReactNativeFeatureFlagsCPP from './templates/js/NativeReactNativeFeatureFlags.cpp-template';
+import NativeReactNativeFeatureFlagsH from './templates/js/NativeReactNativeFeatureFlags.h-template';
+import NativeReactNativeFeatureFlagsJS from './templates/js/NativeReactNativeFeatureFlags.js-template';
+import ReactNativeFeatureFlagsJS from './templates/js/ReactNativeFeatureFlags.js-template';
+import path from 'path';
+
+export default function generateCommonCxxModules(
+  generatorConfig: GeneratorConfig,
+): GeneratorResult {
+  const {jsPath, commonNativeModuleCxxPath, featureFlagDefinitions} =
+    generatorConfig;
 
-module.exports = function generateCommonCxxModules(
-  generatorConfig,
-  featureFlagsConfig,
-) {
   return {
-    [path.join(generatorConfig.jsPath, 'ReactNativeFeatureFlags.js')]:
-      ReactNativeFeatureFlagsJS(featureFlagsConfig),
-    [path.join(generatorConfig.jsPath, 'NativeReactNativeFeatureFlags.js')]:
-      NativeReactNativeFeatureFlagsJS(featureFlagsConfig),
-    [path.join(
-      generatorConfig.commonNativeModuleCxxPath,
-      'NativeReactNativeFeatureFlags.h',
-    )]: NativeReactNativeFeatureFlagsH(featureFlagsConfig),
-    [path.join(
-      generatorConfig.commonNativeModuleCxxPath,
-      'NativeReactNativeFeatureFlags.cpp',
-    )]: NativeReactNativeFeatureFlagsCPP(featureFlagsConfig),
+    [path.join(jsPath, 'ReactNativeFeatureFlags.js')]:
+      ReactNativeFeatureFlagsJS(featureFlagDefinitions),
+    [path.join(jsPath, 'NativeReactNativeFeatureFlags.js')]:
+      NativeReactNativeFeatureFlagsJS(featureFlagDefinitions),
+    [path.join(commonNativeModuleCxxPath, 'NativeReactNativeFeatureFlags.h')]:
+      NativeReactNativeFeatureFlagsH(featureFlagDefinitions),
+    [path.join(commonNativeModuleCxxPath, 'NativeReactNativeFeatureFlags.cpp')]:
+      NativeReactNativeFeatureFlagsCPP(featureFlagDefinitions),
   };
-};
+}

packages/react-native/scripts/featureflags/index.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+if (require.main === module) {
+  require('../../../../scripts/build/babel-register').registerForMonorepo();
+  const update = require('./update').default;
+  update(process.argv.includes('--verify-unchanged'));
+}

packages/react-native/scripts/featureflags/templates/android/JReactNativeFeatureFlagsCxxInterop.cpp-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -33,7 +31,7 @@ ${DO_NOT_MODIFY_COMMENT}
 
 namespace facebook::react {
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `${getCxxTypeFromDefaultValue(
@@ -62,7 +60,7 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
           "override", JReactNativeFeatureFlagsCxxInterop::override),
       makeNativeMethod("dangerouslyReset", JReactNativeFeatureFlagsCxxInterop::dangerouslyReset),
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `      makeNativeMethod(
@@ -75,3 +73,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/android/JReactNativeFeatureFlagsCxxInterop.h-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -40,7 +38,7 @@ class JReactNativeFeatureFlagsCxxInterop
   constexpr static auto kJavaDescriptor =
       "Lcom/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop;";
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  static ${getCxxTypeFromDefaultValue(
@@ -62,3 +60,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/android/ReactNativeFeatureFlags.kt-template.js

@@ -4,16 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {DO_NOT_MODIFY_COMMENT} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -35,7 +36,7 @@ object ReactNativeFeatureFlags {
   private var accessorProvider: () -> ReactNativeFeatureFlagsAccessor = { ReactNativeFeatureFlagsCxxAccessor() }
   private var accessor: ReactNativeFeatureFlagsAccessor = accessorProvider()
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  /**
@@ -90,3 +91,4 @@ ${Object.entries(config.common)
   }
 }
 `);
+}

packages/react-native/scripts/featureflags/templates/android/ReactNativeFeatureFlagsCxxAccessor.kt-template.js

@@ -4,19 +4,20 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
+import {
   DO_NOT_MODIFY_COMMENT,
   getKotlinTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -30,7 +31,7 @@ ${DO_NOT_MODIFY_COMMENT}
 package com.facebook.react.internal.featureflags
 
 class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccessor {
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  private var ${flagName}Cache: ${getKotlinTypeFromDefaultValue(
@@ -39,7 +40,7 @@ ${Object.entries(config.common)
   )
   .join('\n')}
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) => `  override fun ${flagName}(): Boolean {
     var cached = ${flagName}Cache
@@ -58,3 +59,4 @@ ${Object.entries(config.common)
   override fun dangerouslyReset() = ReactNativeFeatureFlagsCxxInterop.dangerouslyReset()
 }
 `);
+}

packages/react-native/scripts/featureflags/templates/android/ReactNativeFeatureFlagsCxxInterop.kt-template.js

@@ -4,19 +4,20 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
+import {
   DO_NOT_MODIFY_COMMENT,
   getKotlinTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -38,7 +39,7 @@ object ReactNativeFeatureFlagsCxxInterop {
     SoLoader.loadLibrary("react_featureflagsjni")
   }
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  @DoNotStrip @JvmStatic external fun ${flagName}(): ${getKotlinTypeFromDefaultValue(
@@ -52,3 +53,4 @@ ${Object.entries(config.common)
   @DoNotStrip @JvmStatic external fun dangerouslyReset()
 }
 `);
+}

packages/react-native/scripts/featureflags/templates/android/ReactNativeFeatureFlagsDefaults.kt-template.js

@@ -4,19 +4,20 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
+import {
   DO_NOT_MODIFY_COMMENT,
   getKotlinTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -33,7 +34,7 @@ open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvider {
   // We could use JNI to get the defaults from C++,
   // but that is more expensive than just duplicating the defaults here.
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  override fun ${flagName}(): ${getKotlinTypeFromDefaultValue(
@@ -43,3 +44,4 @@ ${Object.entries(config.common)
   .join('\n\n')}
 }
 `);
+}

packages/react-native/scripts/featureflags/templates/android/ReactNativeFeatureFlagsLocalAccessor.kt-template.js

@@ -4,19 +4,20 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
+import {
   DO_NOT_MODIFY_COMMENT,
   getKotlinTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -34,7 +35,7 @@ class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAccessor {
 
   private val accessedFeatureFlags = mutableSetOf<String>()
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  private var ${flagName}Cache: ${getKotlinTypeFromDefaultValue(
@@ -43,7 +44,7 @@ ${Object.entries(config.common)
   )
   .join('\n')}
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) => `  override fun ${flagName}(): Boolean {
     var cached = ${flagName}Cache
@@ -72,3 +73,4 @@ ${Object.entries(config.common)
   }
 }
 `);
+}

packages/react-native/scripts/featureflags/templates/android/ReactNativeFeatureFlagsProvider.kt-template.js

@@ -4,19 +4,20 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
+import {
   DO_NOT_MODIFY_COMMENT,
   getKotlinTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -33,7 +34,7 @@ import com.facebook.proguard.annotations.DoNotStrip
 
 @DoNotStrip
 interface ReactNativeFeatureFlagsProvider {
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  @DoNotStrip fun ${flagName}(): ${getKotlinTypeFromDefaultValue(
@@ -43,3 +44,4 @@ ${Object.entries(config.common)
   .join('\n\n')}
 }
 `);
+}

packages/react-native/scripts/featureflags/templates/android/ReactNativeFeatureFlagsProviderHolder.cpp-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -37,7 +35,7 @@ static jni::alias_ref<jni::JClass> getJClass() {
   return jClass;
 }
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `${getCxxTypeFromDefaultValue(
@@ -52,3 +50,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/android/ReactNativeFeatureFlagsProviderHolder.h-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -45,7 +43,7 @@ class ReactNativeFeatureFlagsProviderHolder
       jni::alias_ref<jobject> javaProvider)
       : javaProvider_(make_global(javaProvider)){};
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  ${getCxxTypeFromDefaultValue(
@@ -60,3 +58,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/common-cxx/ReactNativeFeatureFlags.cpp-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -31,7 +29,7 @@ ${DO_NOT_MODIFY_COMMENT}
 
 namespace facebook::react {
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `${getCxxTypeFromDefaultValue(
@@ -62,3 +60,4 @@ ReactNativeFeatureFlagsAccessor& ReactNativeFeatureFlags::getAccessor(
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/common-cxx/ReactNativeFeatureFlags.h-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -43,7 +41,7 @@ namespace facebook::react {
  */
 class ReactNativeFeatureFlags {
  public:
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  /**
@@ -95,3 +93,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/common-cxx/ReactNativeFeatureFlagsAccessor.cpp-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -38,7 +36,7 @@ namespace facebook::react {
 ReactNativeFeatureFlagsAccessor::ReactNativeFeatureFlagsAccessor()
     : currentProvider_(std::make_unique<ReactNativeFeatureFlagsDefaults>()) {}
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig], flagPosition) =>
       `${getCxxTypeFromDefaultValue(
@@ -98,3 +96,4 @@ void ReactNativeFeatureFlagsAccessor::ensureFlagsNotAccessed() {
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/common-cxx/ReactNativeFeatureFlagsAccessor.h-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -41,7 +39,7 @@ class ReactNativeFeatureFlagsAccessor {
  public:
   ReactNativeFeatureFlagsAccessor();
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  ${getCxxTypeFromDefaultValue(flagConfig.defaultValue)} ${flagName}();`,
@@ -56,10 +54,10 @@ ${Object.entries(config.common)
 
   std::unique_ptr<ReactNativeFeatureFlagsProvider> currentProvider_;
   std::array<std::atomic<const char*>, ${
-    Object.keys(config.common).length
+    Object.keys(definitions.common).length
   }> accessedFeatureFlags_;
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  std::atomic<std::optional<${getCxxTypeFromDefaultValue(
@@ -71,3 +69,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/common-cxx/ReactNativeFeatureFlagsDefaults.h-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -37,7 +35,7 @@ class ReactNativeFeatureFlagsDefaults : public ReactNativeFeatureFlagsProvider {
  public:
   ReactNativeFeatureFlagsDefaults() = default;
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  ${getCxxTypeFromDefaultValue(
@@ -51,3 +49,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/common-cxx/ReactNativeFeatureFlagsProvider.h-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -35,7 +33,7 @@ class ReactNativeFeatureFlagsProvider {
  public:
   virtual ~ReactNativeFeatureFlagsProvider() = default;
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  virtual ${getCxxTypeFromDefaultValue(
@@ -47,3 +45,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/js/NativeReactNativeFeatureFlags.cpp-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -45,7 +43,7 @@ NativeReactNativeFeatureFlags::NativeReactNativeFeatureFlags(
     std::shared_ptr<CallInvoker> jsInvoker)
     : NativeReactNativeFeatureFlagsCxxSpec(std::move(jsInvoker)) {}
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `${getCxxTypeFromDefaultValue(
@@ -59,3 +57,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/js/NativeReactNativeFeatureFlags.h-template.js

@@ -4,19 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {
-  DO_NOT_MODIFY_COMMENT,
-  getCxxTypeFromDefaultValue,
-} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT, getCxxTypeFromDefaultValue} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/*
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/*
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -40,7 +38,7 @@ class NativeReactNativeFeatureFlags
  public:
   NativeReactNativeFeatureFlags(std::shared_ptr<CallInvoker> jsInvoker);
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  ${getCxxTypeFromDefaultValue(
@@ -52,3 +50,4 @@ ${Object.entries(config.common)
 
 } // namespace facebook::react
 `);
+}

packages/react-native/scripts/featureflags/templates/js/NativeReactNativeFeatureFlags.js-template.js

@@ -4,16 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {DO_NOT_MODIFY_COMMENT} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/**
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/**
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -30,7 +31,7 @@ import type {TurboModule} from '../../../Libraries/TurboModule/RCTExport';
 import * as TurboModuleRegistry from '../../../Libraries/TurboModule/TurboModuleRegistry';
 
 export interface Spec extends TurboModule {
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  +${flagName}?: () => ${typeof flagConfig.defaultValue};`,
@@ -44,3 +45,4 @@ const NativeReactNativeFeatureFlags: ?Spec = TurboModuleRegistry.get<Spec>(
 
 export default NativeReactNativeFeatureFlags;
 `);
+}

packages/react-native/scripts/featureflags/templates/js/ReactNativeFeatureFlags.js-template.js

@@ -4,16 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-'use strict';
+import type {FeatureFlagDefinitions} from '../../types';
 
-const {DO_NOT_MODIFY_COMMENT} = require('../../utils');
-const signedsource = require('signedsource');
+import {DO_NOT_MODIFY_COMMENT} from '../../utils';
+import signedsource from 'signedsource';
 
-module.exports = config =>
-  signedsource.signFile(`/**
+export default function (definitions: FeatureFlagDefinitions): string {
+  return signedsource.signFile(`/**
  * Copyright (c) Meta Platforms, Inc. and affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -33,7 +34,7 @@ import {
 } from './ReactNativeFeatureFlagsBase';
 
 export type ReactNativeFeatureFlagsJsOnly = {
-${Object.entries(config.jsOnly)
+${Object.entries(definitions.jsOnly)
   .map(
     ([flagName, flagConfig]) =>
       `  ${flagName}: Getter<${typeof flagConfig.defaultValue}>,`,
@@ -45,7 +46,7 @@ export type ReactNativeFeatureFlagsJsOnlyOverrides = Partial<ReactNativeFeatureF
 
 export type ReactNativeFeatureFlags = {
   ...ReactNativeFeatureFlagsJsOnly,
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `  ${flagName}: Getter<${typeof flagConfig.defaultValue}>,`,
@@ -53,7 +54,7 @@ ${Object.entries(config.common)
   .join('\n')}
 }
 
-${Object.entries(config.jsOnly)
+${Object.entries(definitions.jsOnly)
   .map(
     ([flagName, flagConfig]) =>
       `/**
@@ -65,7 +66,7 @@ export const ${flagName}: Getter<${typeof flagConfig.defaultValue}> = createJava
   )
   .join('\n\n')}
 
-${Object.entries(config.common)
+${Object.entries(definitions.common)
   .map(
     ([flagName, flagConfig]) =>
       `/**
@@ -83,3 +84,4 @@ export const ${flagName}: Getter<${typeof flagConfig.defaultValue}> = createNati
  */
 export const override = setOverrides;
 `);
+}

packages/react-native/scripts/featureflags/types.js

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ * @format
+ */
+
+export type FeatureFlagValue = boolean | number | string;
+
+export type FeatureFlagDefinitions = {
+  common: FeatureFlagList,
+  jsOnly: FeatureFlagList,
+};
+
+type FeatureFlagList = {
+  [flagName: string]: {
+    description: string,
+    defaultValue: FeatureFlagValue,
+  },
+};
+
+export type GeneratorConfig = {
+  featureFlagDefinitions: FeatureFlagDefinitions,
+  jsPath: string,
+  commonCxxPath: string,
+  commonNativeModuleCxxPath: string,
+  androidPath: string,
+  androidJniPath: string,
+};
+
+export type GeneratorOptions = {
+  verifyUnchanged: boolean,
+};
+
+export type GeneratorResult = {
+  [path: string]: string /* content */,
+};

packages/react-native/scripts/featureflags/update.js

@@ -4,18 +4,25 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-const generateFiles = require('./generateFiles');
-const path = require('path');
+import generateFiles from './generateFiles';
+import fs from 'fs';
+import path from 'path';
 
 const REACT_NATIVE_PACKAGE_ROOT = path.join(__dirname, '..', '..');
 
-function update() {
+export default function update(verifyUnchanged: boolean): void {
   generateFiles(
     {
-      configPath: path.join(__dirname, 'ReactNativeFeatureFlags.json'),
+      featureFlagDefinitions: JSON.parse(
+        fs.readFileSync(
+          path.join(__dirname, 'ReactNativeFeatureFlags.json'),
+          'utf8',
+        ),
+      ),
       jsPath: path.join(
         REACT_NATIVE_PACKAGE_ROOT,
         'src',
@@ -58,11 +65,7 @@ function update() {
       ),
     },
     {
-      verifyUnchanged: process.argv.includes('--verify-unchanged'),
+      verifyUnchanged,
     },
   );
 }
-
-if (require.main === module) {
-  update();
-}

packages/react-native/scripts/featureflags/utils.js

@@ -4,41 +4,43 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */
 
-module.exports = {
-  getCxxTypeFromDefaultValue: defaultValue => {
-    switch (typeof defaultValue) {
-      case 'boolean':
-        return 'bool';
-      case 'number':
-        return 'int';
-      case 'string':
-        return 'std::string';
-      default:
-        throw new Error(
-          `Unsupported default value type: ${typeof defaultValue}`,
-        );
-    }
-  },
+import type {FeatureFlagValue} from './types';
 
-  getKotlinTypeFromDefaultValue: defaultValue => {
-    switch (typeof defaultValue) {
-      case 'boolean':
-        return 'Boolean';
-      case 'number':
-        return 'Int';
-      case 'string':
-        return 'String';
-      default:
-        throw new Error(
-          `Unsupported default value type: ${typeof defaultValue}`,
-        );
-    }
-  },
+export function getCxxTypeFromDefaultValue(
+  defaultValue: FeatureFlagValue,
+): string {
+  switch (typeof defaultValue) {
+    case 'boolean':
+      return 'bool';
+    case 'number':
+      return 'int';
+    case 'string':
+      return 'std::string';
+    default:
+      throw new Error(`Unsupported default value type: ${typeof defaultValue}`);
+  }
+}
 
-  DO_NOT_MODIFY_COMMENT: `/**
+export function getKotlinTypeFromDefaultValue(
+  defaultValue: FeatureFlagValue,
+): string {
+  switch (typeof defaultValue) {
+    case 'boolean':
+      return 'Boolean';
+    case 'number':
+      return 'Int';
+    case 'string':
+      return 'String';
+    default:
+      throw new Error(`Unsupported default value type: ${typeof defaultValue}`);
+  }
+}
+
+export const DO_NOT_MODIFY_COMMENT = `/**
  * IMPORTANT: Do NOT modify this file directly.
  *
  * To change the definition of the flags, edit
@@ -46,5 +48,4 @@ module.exports = {
  *
  * To regenerate this code, run the following script from the repo root:
  *   yarn featureflags-update
- */`,
-};
+ */`;