Optional post-transform pipeline for .d.ts files generated by build-types script (#49634)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/49634

Changelog: [Internal]

Reviewed By: huntie

Differential Revision: D69992512

fbshipit-source-id: 7fc004e9460498de236a833aea5265a5fac5f490

package.json

@@ -45,6 +45,7 @@
     "@babel/core": "^7.25.2",
     "@babel/eslint-parser": "^7.25.1",
     "@babel/generator": "^7.25.0",
+    "@babel/plugin-syntax-typescript": "^7.25.4",
     "@babel/plugin-transform-regenerator": "^7.24.7",
     "@babel/preset-env": "^7.25.3",
     "@babel/preset-flow": "^7.24.7",

scripts/build/build-types/translateSourceFile.js

@@ -9,21 +9,24 @@
  * @oncall react_native
  */
 
+import type {PluginObj} from '@babel/core';
 import type {ParseResult} from 'hermes-transform/dist/transform/parse';
 import type {TransformASTResult} from 'hermes-transform/dist/transform/transformAST';
 
 const getDependencies = require('./resolution/getDependencies');
+const babel = require('@babel/core');
 const translate = require('flow-api-translator');
 const {parse, print} = require('hermes-transform');
 
-type TransformFn = ParseResult => Promise<TransformASTResult>;
+type PreTransformFn = ParseResult => Promise<TransformASTResult>;
 
-const preTransforms: Array<TransformFn> = [
+const preTransforms: Array<PreTransformFn> = [
   require('./transforms/stripPrivateProperties'),
   require('./transforms/replaceRequiresWithImports'),
   require('./transforms/replaceEmptyWithNever'),
   require('./transforms/replaceStringishWithString'),
 ];
+const postTransforms: Array<PluginObj<mixed>> = [];
 const prettierOptions = {parser: 'babel'};
 const unsupportedFeatureRegex =
   /Unsupported feature: Translating ".*" is currently not supported/;
@@ -47,7 +50,7 @@ async function translateSourceFile(
   const parsed = await parse(source);
 
   // Apply pre-transforms
-  const preTransformResult = await applyTransforms(parsed, preTransforms);
+  const preTransformResult = await applyPreTransforms(parsed);
 
   // Translate to Flow defs (prunes non-type imports)
   const flowDefResult = await translate.translateFlowToFlowDef(
@@ -62,27 +65,27 @@ async function translateSourceFile(
   );
 
   // Translate to TypeScript defs
-  const result = await translate.translateFlowToTSDef(
+  const tsDefResult = await translate.translateFlowToTSDef(
     flowDefResult,
     prettierOptions,
   );
 
-  const unsupportedFeatureMatch = result.match(unsupportedFeatureRegex);
+  const unsupportedFeatureMatch = tsDefResult.match(unsupportedFeatureRegex);
   if (unsupportedFeatureMatch != null) {
     throw new Error(`Error: ${unsupportedFeatureMatch[0]}`);
   }
 
+  // Apply post-transforms
+  const result = await applyPostTransforms(tsDefResult);
+
   return {
     result,
     dependencies,
   };
 }
 
-async function applyTransforms(
-  source: ParseResult,
-  transforms: $ReadOnlyArray<TransformFn>,
-): Promise<ParseResult> {
-  return transforms.reduce((input, transform) => {
+async function applyPreTransforms(source: ParseResult): Promise<ParseResult> {
+  return preTransforms.reduce((input, transform) => {
     return input.then(async result => {
       const transformed = await transform(result);
       const code = transformed.astWasMutated
@@ -94,4 +97,20 @@ async function applyTransforms(
   }, Promise.resolve(source));
 }
 
+/**
+ * Apply post-transforms to .d.ts source code containing @build-types directives.
+ */
+async function applyPostTransforms(source: string): Promise<string> {
+  if (!source.includes('@build-types')) {
+    // Exiting early, as there are no @build-types directives
+    return source;
+  }
+
+  const result = await babel.transformAsync(source, {
+    plugins: ['@babel/plugin-syntax-typescript', ...postTransforms],
+  });
+
+  return result.code;
+}
+
 module.exports = translateSourceFile;

yarn.lock

@@ -160,6 +160,11 @@
   resolved "https://registry.yarnpkg.com/@babel/helper-plugin-utils/-/helper-plugin-utils-7.24.8.tgz#94ee67e8ec0e5d44ea7baeb51e571bd26af07878"
   integrity sha512-FFWx5142D8h2Mgr/iPVGH5G7w6jDn4jUSpZTyDnQO0Yn7Ks2Kuz6Pci8H6MPCoUJegd/UZQ3tAvfLCxQSnWWwg==
 
+"@babel/helper-plugin-utils@^7.25.9":
+  version "7.26.5"
+  resolved "https://registry.yarnpkg.com/@babel/helper-plugin-utils/-/helper-plugin-utils-7.26.5.tgz#18580d00c9934117ad719392c4f6585c9333cc35"
+  integrity sha512-RS+jZcRdZdRFzMyr+wcsaqOmld1/EqTghfaBGQQd/WnRdzdlvSZ//kF7U8VQTxf1ynZ4cjUcYgjVGx13ewNPMg==
+
 "@babel/helper-remap-async-to-generator@^7.24.7", "@babel/helper-remap-async-to-generator@^7.25.0":
   version "7.25.0"
   resolved "https://registry.yarnpkg.com/@babel/helper-remap-async-to-generator/-/helper-remap-async-to-generator-7.25.0.tgz#d2f0fbba059a42d68e5e378feaf181ef6055365e"
@@ -482,6 +487,13 @@
   dependencies:
     "@babel/helper-plugin-utils" "^7.24.8"
 
+"@babel/plugin-syntax-typescript@^7.25.4":
+  version "7.25.9"
+  resolved "https://registry.yarnpkg.com/@babel/plugin-syntax-typescript/-/plugin-syntax-typescript-7.25.9.tgz#67dda2b74da43727cf21d46cf9afef23f4365399"
+  integrity sha512-hjMgRy5hb8uJJjUcdWunWVcoi9bGpJp8p5Ol1229PoN6aytsLwNMgmdftO23wnCLMfVmTwZDWMPNq/D1SY60JQ==
+  dependencies:
+    "@babel/helper-plugin-utils" "^7.25.9"
+
 "@babel/plugin-syntax-unicode-sets-regex@^7.18.6":
   version "7.18.6"
   resolved "https://registry.yarnpkg.com/@babel/plugin-syntax-unicode-sets-regex/-/plugin-syntax-unicode-sets-regex-7.18.6.tgz#d49a3b3e6b52e5be6740022317580234a6a47357"