RN: Flowify packages/react-native-scripts (#51671)

Summary:
Pull Request resolved: #51671

Adds `flow` (or `noflow`) to all files in this directory and ensures that Flow succeeds (by adding type annotations, using minor refactors, or suppressing errors due to intentionally dynamic logic).

This will help improve type safety when making changes both in these files as well as files that these depend on.

Changelog:
[Internal]

Reviewed By: SamChou19815

Differential Revision: D75581879

fbshipit-source-id: 6dcd8cc55d0021973eeae2670c1ebceb6d69fa8f

Author: yungsters

packages/react-native/scripts/bundle.js

@@ -4,6 +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 strict-local
  * @format
  */
 
@@ -16,6 +17,7 @@ const {readFileSync} = require('fs');
 const path = require('path');
 
 // Commander 12.0.0 changes from the global to named export
+// $FlowFixMe[signature-verification-failure]
 const program = commander.program ?? commander;
 
 program.version(
@@ -37,7 +39,14 @@ program
   .allowUnknownOption()
   .action(async function handleAction() {
     let config = null;
-    let options = program.opts();
+    let options = program
+      .opts /*::<{
+      configCmd?: string,
+      loadConfig?: string,
+      verbose: boolean,
+      ...
+    }>*/
+      ();
     if (options.loadConfig != null) {
       config = JSON.parse(
         options.loadConfig.replace(/^\W*'/, '').replace(/'\W*$/, ''),

packages/react-native/scripts/codegen/__fixtures__/fixtures.js

@@ -4,6 +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 strict-local
  * @format
  */
 
@@ -120,6 +121,7 @@ const SCHEMA_TEXT = `
 }
 `;
 
+// $FlowFixMe[signature-verification-failure]
 const SCHEMA = JSON.parse(SCHEMA_TEXT);
 
 module.exports = {

packages/react-native/scripts/codegen/__tests__/generate-artifacts-executor-test.js

@@ -4,6 +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 strict-local
  * @format
  */
 
@@ -243,7 +244,7 @@ describe('delete empty files and folders', () => {
 
   it("when path is folder and it's empty, removes it", () => {
     const targetFolder = 'build';
-    const content = [];
+    const content = [] as Array<string>;
 
     let statSyncInvocationCount = 0;
     let readdirInvocationCount = 0;
@@ -290,8 +291,8 @@ describe('delete empty files and folders', () => {
       path.normalize('build/notEmptyFile'),
     ];
 
-    const emptyContent = [];
-    let fileSizes = {};
+    const emptyContent = [] as Array<string>;
+    let fileSizes = {} as {[string]: number};
     fileSizes[path.normalize('build/emptyFile')] = 0;
     fileSizes[path.normalize('build/notEmptyFile')] = 32;
 
@@ -344,7 +345,7 @@ describe('delete empty files and folders', () => {
   it('when path is folder and it contains only empty folders, removes everything', () => {
     const targetFolder = 'build';
     const content = ['emptyFolder1', 'emptyFolder2'];
-    const emptyContent = [];
+    const emptyContent = [] as Array<string>;
 
     let statSyncInvocation = [];
     let rmSyncInvocation = [];

packages/react-native/scripts/codegen/__tests__/generate-specs-cli-executor-test.js

@@ -4,6 +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 strict-local
  * @format
  */
 

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

@@ -4,6 +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 strict-local
  * @format
  */
 
@@ -19,11 +20,13 @@
  *
  * @return an object that can generate the code for the New Architecture.
  */
-function getCodegen() {
+function getCodegen() /*: $FlowFixMe */ {
   let RNCodegen;
   try {
+    // $FlowIgnore[cannot-resolve-module]
     RNCodegen = require('../../packages/react-native-codegen/lib/generators/RNCodegen.js');
   } catch (e) {
+    // $FlowIgnore[cannot-resolve-module]
     RNCodegen = require('@react-native/codegen/lib/generators/RNCodegen.js');
   }
   if (!RNCodegen) {
@@ -32,11 +35,13 @@ function getCodegen() {
   return RNCodegen;
 }
 
-function getCombineJSToSchema() {
+function getCombineJSToSchema() /*: $FlowFixMe */ {
   let combineJSToSchema;
   try {
+    // $FlowIgnore[cannot-resolve-module]
     combineJSToSchema = require('../../packages/react-native-codegen/lib/cli/combine/combine-js-to-schema.js');
   } catch (e) {
+    // $FlowIgnore[cannot-resolve-module]
     combineJSToSchema = require('@react-native/codegen/lib/cli/combine/combine-js-to-schema.js');
   }
   if (!combineJSToSchema) {
@@ -46,6 +51,6 @@ function getCombineJSToSchema() {
 }
 
 module.exports = {
-  getCodegen: getCodegen,
-  getCombineJSToSchema: getCombineJSToSchema,
+  getCodegen,
+  getCombineJSToSchema,
 };

packages/react-native/scripts/codegen/generate-artifacts-executor/constants.js

@@ -4,6 +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 strict-local
  * @format
  */
 
@@ -21,54 +22,63 @@ const REACT_NATIVE_REPOSITORY_ROOT = path.join(
   '..',
 );
 
-const REACT_NATIVE_PACKAGE_ROOT_FOLDER = path.join(__dirname, '..', '..', '..');
+const REACT_NATIVE_PACKAGE_ROOT_FOLDER = path.join(
+    __dirname,
+    '..',
+    '..',
+    '..',
+  ) /*:: as string */;
 const CODEGEN_REPO_PATH = `${REACT_NATIVE_REPOSITORY_ROOT}/packages/react-native-codegen`;
 
 const RNCORE_CONFIGS = {
-  ios: path.join(REACT_NATIVE_PACKAGE_ROOT_FOLDER, 'ReactCommon'),
+  ios: path.join(
+    REACT_NATIVE_PACKAGE_ROOT_FOLDER,
+    'ReactCommon',
+  ) /*:: as string */,
   android: path.join(
     REACT_NATIVE_PACKAGE_ROOT_FOLDER,
     'ReactAndroid',
     'build',
     'generated',
     'source',
     'codegen',
-  ),
+  ) /*:: as string */,
 };
 
 const CORE_LIBRARIES_WITH_OUTPUT_FOLDER = {
-  rncore: RNCORE_CONFIGS,
-  FBReactNativeSpec: {
-    ios: path.join(
-      REACT_NATIVE_PACKAGE_ROOT_FOLDER,
-      'React',
-      'FBReactNativeSpec',
-    ),
-    android: path.join(
-      REACT_NATIVE_PACKAGE_ROOT_FOLDER,
-      'ReactAndroid',
-      'build',
-      'generated',
-      'source',
-      'codegen',
-    ),
-  },
-};
+    rncore: RNCORE_CONFIGS,
+    FBReactNativeSpec: {
+      ios: path.join(
+        REACT_NATIVE_PACKAGE_ROOT_FOLDER,
+        'React',
+        'FBReactNativeSpec',
+      ) /*:: as string */,
+      android: path.join(
+        REACT_NATIVE_PACKAGE_ROOT_FOLDER,
+        'ReactAndroid',
+        'build',
+        'generated',
+        'source',
+        'codegen',
+      ) /*:: as string */,
+    },
+  } /*:: as {[string]: $FlowFixMe} */;
 
 const packageJsonPath = path.join(
   REACT_NATIVE_PACKAGE_ROOT_FOLDER,
   'package.json',
 );
 
-const packageJson = JSON.parse(fs.readFileSync(packageJsonPath));
+// $FlowFixMe[signature-verification-failure]
+const packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
 const REACT_NATIVE = packageJson.name;
 
 const TEMPLATES_FOLDER_PATH = path.join(
-  REACT_NATIVE_PACKAGE_ROOT_FOLDER,
-  'scripts',
-  'codegen',
-  'templates',
-);
+    REACT_NATIVE_PACKAGE_ROOT_FOLDER,
+    'scripts',
+    'codegen',
+    'templates',
+  ) /*:: as string */;
 
 module.exports = {
   CODEGEN_REPO_PATH,

packages/react-native/scripts/codegen/generate-artifacts-executor/generateAppDependencyProvider.js

@@ -4,6 +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 strict-local
  * @format
  */
 
@@ -28,7 +29,7 @@ const APP_DEPENDENCY_PROVIDER_PODSPEC_TEMPLATE_PATH = path.join(
   'ReactAppDependencyProvider.podspec.template',
 );
 
-function generateAppDependencyProvider(outputDir) {
+function generateAppDependencyProvider(outputDir /*: string */) {
   fs.mkdirSync(outputDir, {recursive: true});
   codegenLog('Generating RCTAppDependencyProvider');
 

packages/react-native/scripts/codegen/generate-artifacts-executor/generateCustomURLHandlers.js

@@ -4,6 +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 strict-local
  * @format
  */
 
@@ -23,13 +24,17 @@ const MODULES_PROTOCOLS_MM_TEMPLATE_PATH = path.join(
   'RCTModulesConformingToProtocolsProviderMM.template',
 );
 
-function generateCustomURLHandlers(libraries, outputDir) {
+function generateCustomURLHandlers(
+  libraries /*: $ReadOnlyArray<$FlowFixMe> */,
+  outputDir /*: string */,
+) {
   const iosAnnotations = parseiOSAnnotations(libraries);
 
-  const imageURLLoaderModules = new Set();
-  const imageDataDecoderModules = new Set();
-  const urlRequestHandlersModules = new Set();
+  const imageURLLoaderModules = new Set /*::<string>*/();
+  const imageDataDecoderModules = new Set /*::<string>*/();
+  const urlRequestHandlersModules = new Set /*::<string>*/();
 
+  // $FlowFixMe[missing-local-annot]]
   const wrapInArrayIfNecessary = value =>
     Array.isArray(value) || value == null ? value : [value];
   // Old API

packages/react-native/scripts/codegen/generate-artifacts-executor/generateFBReactNativeSpecIOS.js

@@ -4,6 +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 strict-local
  * @format
  */
 

packages/react-native/scripts/codegen/generate-artifacts-executor/generateNativeCode.js

@@ -4,6 +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 strict-local
  * @format
  */
 
@@ -17,17 +18,22 @@ const os = require('os');
 const path = require('path');
 
 function generateNativeCode(
-  outputPath,
-  schemaInfos,
-  includesGeneratedCode,
-  platform,
-) {
+  outputPath /*: string */,
+  schemaInfos /*: $ReadOnlyArray<$FlowFixMe> */,
+  includesGeneratedCode /*: boolean */,
+  platform /*: string */,
+) /*: Array<void> */ {
   return schemaInfos.map(schemaInfo => {
     generateCode(outputPath, schemaInfo, includesGeneratedCode, platform);
   });
 }
 
-function generateCode(outputPath, schemaInfo, includesGeneratedCode, platform) {
+function generateCode(
+  outputPath /*: string */,
+  schemaInfo /*: $FlowFixMe */,
+  includesGeneratedCode /*: boolean */,
+  platform /*: string */,
+) {
   if (shouldSkipGenerationForRncore(schemaInfo, platform)) {
     codegenLog(
       '[Codegen - rncore] Skipping iOS code generation for rncore as it has been generated already.',
@@ -65,11 +71,15 @@ function generateCode(outputPath, schemaInfo, includesGeneratedCode, platform) {
   const outputDir =
     reactNativeCoreLibraryOutputPath(libraryName, platform) ?? outputPath;
   fs.mkdirSync(outputDir, {recursive: true});
+  // $FlowIssue[prop-missing] - `fs.cpSync` is missing in Flow libdefs.
   fs.cpSync(tmpOutputDir, outputDir, {recursive: true});
   codegenLog(`Generated artifacts: ${outputDir}`);
 }
 
-function shouldSkipGenerationForRncore(schemaInfo, platform) {
+function shouldSkipGenerationForRncore(
+  schemaInfo /*: $FlowFixMe */,
+  platform /*: string */,
+) {
   if (platform !== 'ios' || schemaInfo.library.config.name !== 'rncore') {
     return false;
   }
@@ -82,13 +92,19 @@ function shouldSkipGenerationForRncore(schemaInfo, platform) {
   );
 }
 
-function reactNativeCoreLibraryOutputPath(libraryName, platform) {
+function reactNativeCoreLibraryOutputPath(
+  libraryName /*: string */,
+  platform /*: string */,
+) {
   return CORE_LIBRARIES_WITH_OUTPUT_FOLDER[libraryName]
     ? CORE_LIBRARIES_WITH_OUTPUT_FOLDER[libraryName][platform]
     : null;
 }
 
-function shouldSkipGenerationForFBReactNativeSpec(schemaInfo, platform) {
+function shouldSkipGenerationForFBReactNativeSpec(
+  schemaInfo /*: $FlowFixMe */,
+  platform /*: string */,
+) {
   if (
     platform !== 'ios' ||
     schemaInfo.library.config.name !== 'FBReactNativeSpec'