Respect react-private-interface as runtime-only in js-api typegen

Hardcode support for the react-native/react-private-interface package
export ("types": null) so build-types does not expand src/private/*
dependencies into types_generated.

This unblocks exposing ReactNativeFeatureFlags through
react-private-interface (#57940).

- Skip the import in simpleResolve
- Do not follow src/private deps from react-private-interface.js.flow
- Strip ./private/* re-exports from the generated .d.ts
- Give api-extractor a minimal temp exports map for this subpath

Co-authored-by: Alex Hunt <huntie@users.noreply.github.com>

Author: cursoragent

scripts/js-api/build-types/buildApiSnapshot.js

@@ -303,8 +303,13 @@ async function generateConfigFiles(tempDirectory: string) {
     adjustedApiExtractorConfig,
   );
 
-  // generate basic package.json
-  const packageJSON = {name: 'react-native'};
+  const {
+    API_EXTRACTOR_TEMP_EXPORTS,
+  } = require('./resolution/reactPrivateInterface');
+  const packageJSON = {
+    name: 'react-native',
+    exports: API_EXTRACTOR_TEMP_EXPORTS,
+  };
   await fs.writeFile(
     path.join(tempDirectory, 'package.json'),
     JSON.stringify(packageJSON, null, 2),

scripts/js-api/build-types/resolution/getDependencies.js

@@ -12,6 +12,7 @@ import type {DependencyContext} from './simpleResolve';
 import type {ParseResult} from 'flow-transform/dist/transform/parse';
 
 const resolveTypeInputFile = require('./resolveTypeInputFile');
+const {shouldExpandDependency} = require('./reactPrivateInterface');
 const simpleResolve = require('./simpleResolve');
 const debug = require('debug')('build-types:resolution');
 const {traverse} = require('flow-transform/dist/traverse/traverse');
@@ -82,7 +83,14 @@ async function getDependencies(
       );
 
       if (resolved != null) {
-        dependencies.add(resolveTypeInputFile(resolved) ?? resolved);
+        const dependency = resolveTypeInputFile(resolved) ?? resolved;
+        if (!shouldExpandDependency(filePath, dependency)) {
+          debug(
+            `Skipping private dependency from react-private-interface: '${importPath}' in ${filePath}`,
+          );
+          return;
+        }
+        dependencies.add(dependency);
       }
     }),
   );

scripts/js-api/build-types/resolution/reactPrivateInterface.js

@@ -0,0 +1,83 @@
+/**
+ * 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-local
+ * @format
+ */
+
+const {REACT_NATIVE_PACKAGE_DIR} = require('../../../shared/consts');
+const path = require('node:path');
+
+const REACT_PRIVATE_INTERFACE_IMPORT = 'react-native/react-private-interface';
+
+const REACT_PRIVATE_INTERFACE_FILES: Set<string> = new Set([
+  path.join(REACT_NATIVE_PACKAGE_DIR, 'src/react-private-interface.js'),
+  path.join(REACT_NATIVE_PACKAGE_DIR, 'src/react-private-interface.js.flow'),
+]);
+
+function isReactPrivateInterfaceImport(importPath: string): boolean {
+  return importPath === REACT_PRIVATE_INTERFACE_IMPORT;
+}
+
+function isReactPrivateInterfaceFile(filePath: string): boolean {
+  return REACT_PRIVATE_INTERFACE_FILES.has(path.resolve(filePath));
+}
+
+function isPrivateSourceDependency(depFile: string): boolean {
+  const relativeFromPackage = path.relative(
+    REACT_NATIVE_PACKAGE_DIR,
+    path.resolve(depFile),
+  );
+
+  if (relativeFromPackage === '' || relativeFromPackage.startsWith('..')) {
+    return false;
+  }
+
+  const privatePrefix = 'src' + path.sep + 'private' + path.sep;
+  return (
+    relativeFromPackage === 'src' + path.sep + 'private' ||
+    relativeFromPackage.startsWith(privatePrefix)
+  );
+}
+
+/**
+ * `react-private-interface` is a runtime-only package export (`"types": null`).
+ * Do not expand its `src/private/*` dependencies into generated types.
+ */
+function shouldExpandDependency(fromFile: string, depFile: string): boolean {
+  if (!isReactPrivateInterfaceFile(fromFile)) {
+    return true;
+  }
+  return !isPrivateSourceDependency(depFile);
+}
+
+function isPrivateModuleSpecifier(specifier: string): boolean {
+  return (
+    specifier.startsWith('./private/') || specifier.startsWith('../private/')
+  );
+}
+
+/**
+ * Minimal exports map for the api-extractor temp layout so TypeScript does not
+ * treat `react-private-interface` as a typed entry point.
+ */
+const API_EXTRACTOR_TEMP_EXPORTS = {
+  '.': {
+    types: './react-native/index.d.ts',
+  },
+  './react-private-interface': {
+    types: null,
+    default: './react-native/src/react-private-interface.js',
+  },
+};
+
+module.exports = {
+  API_EXTRACTOR_TEMP_EXPORTS,
+  isPrivateModuleSpecifier,
+  isReactPrivateInterfaceFile,
+  isReactPrivateInterfaceImport,
+  shouldExpandDependency,
+};

scripts/js-api/build-types/resolution/simpleResolve.js

@@ -10,6 +10,9 @@
 
 const {PACKAGES_DIR} = require('../../../shared/consts');
 const {getPackages} = require('../../../shared/monorepoUtils');
+const {
+  isReactPrivateInterfaceImport,
+} = require('./reactPrivateInterface');
 const {existsSync} = require('node:fs');
 const path = require('node:path');
 
@@ -38,6 +41,11 @@ async function simpleResolve(
     });
   }
 
+  // Runtime-only package export — not part of the generated type graph.
+  if (isReactPrivateInterfaceImport(importPath)) {
+    return null;
+  }
+
   // Resolve exact '@react-native/<package>' import
   if (importPath in cachedProjectInfo) {
     const packageJson = cachedProjectInfo[importPath].packageJson;

scripts/js-api/build-types/templates/api-extractor.json

@@ -8,8 +8,7 @@
         "compilerOptions": {
           "lib": ["es2020"],
           "types": [],
-          "moduleResolution": "bundler",
-          "customConditions": ["react-native-strict-api"]
+          "moduleResolution": "bundler"
         }
       }
     },

scripts/js-api/build-types/transforms/typescript/stripReactPrivateInterfacePrivateExports.js

@@ -0,0 +1,44 @@
+/**
+ * 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-local
+ * @format
+ */
+
+import type {PluginObj} from '@babel/core';
+
+const {
+  isPrivateModuleSpecifier,
+} = require('../../resolution/reactPrivateInterface');
+
+/**
+ * `react-private-interface` is exported at runtime only (`"types": null`).
+ * Strip `./private/*` re-exports from its generated `.d.ts`.
+ */
+const stripReactPrivateInterfacePrivateExports: PluginObj<unknown> = {
+  visitor: {
+    ImportDeclaration(nodePath) {
+      if (isPrivateModuleSpecifier(nodePath.node.source.value)) {
+        nodePath.remove();
+      }
+    },
+    ExportNamedDeclaration(nodePath) {
+      if (
+        nodePath.node.source != null &&
+        isPrivateModuleSpecifier(nodePath.node.source.value)
+      ) {
+        nodePath.remove();
+      }
+    },
+    ExportAllDeclaration(nodePath) {
+      if (isPrivateModuleSpecifier(nodePath.node.source.value)) {
+        nodePath.remove();
+      }
+    },
+  },
+};
+
+module.exports = stripReactPrivateInterfacePrivateExports;

scripts/js-api/build-types/translateSourceFile.js

@@ -13,6 +13,9 @@ import type {ParseResult} from 'flow-transform/dist/transform/parse';
 import type {TransformASTResult} from 'flow-transform/dist/transform/transformAST';
 
 const getDependencies = require('./resolution/getDependencies');
+const {
+  isReactPrivateInterfaceFile,
+} = require('./resolution/reactPrivateInterface');
 const applyBabelTransformsSeq = require('./utils/applyBabelTransformsSeq');
 const translate = require('flow-api-translator');
 const {parse, print} = require('flow-transform');
@@ -28,12 +31,22 @@ const preTransforms: Array<PreTransformFn> = [
   require('./transforms/flow/reattachDocComments'),
   require('./transforms/flow/ensureNoUnprefixedProps'),
 ];
-const postTransforms = (filePath: string): Array<PluginObj<unknown>> => [
-  require('./transforms/typescript/convertTypeAliasesToInterfaces'),
-  require('./transforms/typescript/ensureUndefinedOnOptionalMembers'),
-  require('./transforms/typescript/replaceProtectedConstructors'),
-  require('./transforms/typescript/replaceDefaultExportName')(filePath),
-];
+const postTransforms = (filePath: string): Array<PluginObj<unknown>> => {
+  const transforms: Array<PluginObj<unknown>> = [
+    require('./transforms/typescript/convertTypeAliasesToInterfaces'),
+    require('./transforms/typescript/ensureUndefinedOnOptionalMembers'),
+    require('./transforms/typescript/replaceProtectedConstructors'),
+    require('./transforms/typescript/replaceDefaultExportName')(filePath),
+  ];
+
+  if (isReactPrivateInterfaceFile(filePath)) {
+    transforms.push(
+      require('./transforms/typescript/stripReactPrivateInterfacePrivateExports'),
+    );
+  }
+
+  return transforms;
+};
 const prettierOptions = {parser: 'babel'};
 const unsupportedFeatureRegex =
   /Unsupported feature: Translating ".*" is currently not supported/;