Bootstrap experimental types build for main package (#48661)

Summary:


Changelog: [Internal]

Differential Revision: D68102875

scripts/build/build.js

@@ -10,6 +10,7 @@
  */
 
 const {PACKAGES_DIR, REPO_ROOT} = require('../consts');
+const buildRNTypes = require('./buildRNTypes');
 const {
   buildConfig,
   getBabelConfig,
@@ -35,15 +36,16 @@ const IGNORE_PATTERN = '**/__{tests,mocks,fixtures}__/**';
 const config = {
   allowPositionals: true,
   options: {
-    help: {type: 'boolean'},
     check: {type: 'boolean'},
+    experimentalBuildRNTypes: {type: 'boolean'},
+    help: {type: 'boolean'},
   },
 };
 
 async function build() {
   const {
     positionals: packageNames,
-    values: {help, check},
+    values: {check, experimentalBuildRNTypes, help},
   } = parseArgs(config);
 
   if (help) {
@@ -54,6 +56,13 @@ async function build() {
 
   By default, builds all packages defined in ./scripts/build/config.js. If a
   a package list is provided, builds only those specified.
+
+  Options:
+    --check           Validate that no build artifacts have been accidentally
+                      committed.
+    --experimentalBuildRNTypes
+                      [Experimental] Enable source code -> type translation
+                      output for the react-native package.
     `);
     process.exitCode = 0;
     return;
@@ -69,6 +78,16 @@ async function build() {
 
   let ok = true;
   for (const packageName of packagesToBuild) {
+    if (packageName === 'react-native' && !experimentalBuildRNTypes) {
+      if (packagesToBuild.length === 1) {
+        console.warn(
+          'Building the react-native package must be enabled using ' +
+            '--experimentalBuildRNTypes.',
+        );
+      }
+      continue;
+    }
+
     if (check) {
       ok &&= await checkPackage(packageName);
     } else {
@@ -83,15 +102,21 @@ async function checkPackage(packageName /*: string */) /*: Promise<boolean> */ {
   const artifacts = await exportedBuildArtifacts(packageName);
   if (artifacts.length > 0) {
     console.log(
-      `${chalk.bgRed(packageName)}: has been build and the ${chalk.bold('build artifacts')} committed to the repository. This will break Flow checks.`,
+      `${chalk.bgRed(packageName)}: has been built and the ${chalk.bold('build artifacts')} committed to the repository. This will break Flow checks.`,
     );
     return false;
   }
   return true;
 }
 
 async function buildPackage(packageName /*: string */) {
-  const {emitTypeScriptDefs} = getBuildOptions(packageName);
+  const {target, emitTypeScriptDefs} = getBuildOptions(packageName);
+
+  if (target === 'react-native-emit-types') {
+    await buildRNTypes();
+    return;
+  }
+
   const entryPoints = await getEntryPoints(packageName);
 
   const files = glob

scripts/build/buildRNTypes.js

@@ -0,0 +1,67 @@
+/**
+ * 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
+ * @format
+ * @oncall react_native
+ */
+
+const {PACKAGES_DIR} = require('../consts');
+const translate = require('flow-api-translator');
+const {promises: fs} = require('fs');
+const glob = require('glob');
+const path = require('path');
+
+const TYPES_DIR = 'new-types';
+const PACKAGE_NAME = 'react-native';
+
+// Start with Animated only as it using the export syntax.
+const PATHS = ['Libraries/Animated'];
+
+async function buildRNTypes() {
+  const files = PATHS.flatMap(src_path =>
+    glob.sync(path.resolve(PACKAGES_DIR, PACKAGE_NAME, src_path, '**/*.js'), {
+      nodir: true,
+    }),
+  );
+
+  console.log('Building RN types...');
+  for (const file of files) {
+    // Don't build tests
+    if (/\/__tests__\//.test(file)) {
+      continue;
+    }
+
+    const buildPath = getBuildPath(file);
+    const source = await fs.readFile(file, 'utf-8');
+    const prettierConfig = {parser: 'babel'};
+
+    await fs.mkdir(path.dirname(buildPath), {recursive: true});
+
+    try {
+      await fs.writeFile(
+        buildPath,
+        await translate.translateFlowToTSDef(source, prettierConfig),
+      );
+    } catch (e) {
+      console.error(`Failed to build ${file.replace(PACKAGES_DIR, '')}`);
+    }
+  }
+}
+
+function getBuildPath(file /*: string */) /*: string */ {
+  const packageDir = path.join(PACKAGES_DIR, PACKAGE_NAME);
+
+  return path.join(
+    packageDir,
+    file
+      .replace(packageDir, TYPES_DIR)
+      .replace(/\.flow\.js$/, '.js')
+      .replace(/\.js$/, '.d.ts'),
+  );
+}
+
+module.exports = buildRNTypes;

scripts/build/config.js

@@ -18,7 +18,12 @@ const {ModuleResolutionKind} = require('typescript');
 /*::
 export type BuildOptions = $ReadOnly<{
   // The target runtime to compile for.
-  target: 'node',
+  target:
+    // Node.js
+    'node' |
+    // [Experimental] react-native package only: Skip build, emit translated
+    // TypeScript types for 3P use.
+    'react-native-emit-types',
 
   // Whether to emit Flow definition files (.js.flow) (default: true).
   emitFlowDefs?: boolean,
@@ -58,6 +63,9 @@ const buildConfig /*: BuildConfig */ = {
       emitTypeScriptDefs: true,
       target: 'node',
     },
+    'react-native': {
+      target: 'react-native-emit-types',
+    },
   },
 };
 
@@ -83,6 +91,8 @@ function getBabelConfig(
   switch (target) {
     case 'node':
       return require('./babel/node.config.js');
+    case 'react-native-emit-types':
+      return {}; // stub
   }
 }