Allow configuring Babel runtime via caller in @react-native/babel-preset (#57974)

Summary:
Pull Request resolved: #57974

Adds a mechanism for callers to configure `babel/plugin-transform-runtime`
programmatically via Babel caller data, in addition to preset options.

- `enableBabelRuntime` (boolean toggle, or a string to pin a specific
  `babel/runtime` version) can now be read from the Babel caller.
- `babelRuntimeModuleName` (the module helpers are imported from) can be
  provided via preset options or the Babel caller.

Both values are passed as separate primitives (Babel only permits primitive
caller values). Preset options take precedence over caller data, consistent
with how `unstable_transformProfile` is resolved.

Changelog:
[General][Added] - Allow `react-native/babel-preset` to read `enableBabelRuntime` and `babelRuntimeModuleName` from Babel caller data

Reviewed By: vzaidman

Differential Revision: D114070686

fbshipit-source-id: c65928adc0886805fa56f944f7fff50a30ae268b

Author: cortinico

packages/react-native-babel-preset/src/__tests__/transform-runtime-caller-test.js

@@ -0,0 +1,130 @@
+/**
+ * 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
+ */
+
+'use strict';
+
+// $FlowExpectedError[untyped-import] - Preset is untyped
+const preset = require('../index');
+const babel = require('@babel/core');
+
+const MOCK_FILENAME = '/absolute/path/to/input.js';
+
+function transformWithCaller(
+  code: string,
+  options: {[string]: unknown},
+  caller: {
+    enableBabelRuntime?: boolean | string,
+    babelRuntimeModuleName?: string,
+  },
+): string | null {
+  const result = babel.transformSync(code, {
+    babelrc: false,
+    configFile: false,
+    filename: MOCK_FILENAME,
+    presets: [[preset, options]],
+    caller: {...caller, name: 'test'},
+    sourceMaps: false,
+    compact: false,
+  });
+  return result?.code ?? null;
+}
+
+describe('babel runtime caller options', () => {
+  it('uses caller-provided babelRuntimeModuleName for runtime helpers', () => {
+    const code = 'const {a, ...rest} = obj;';
+    const result = transformWithCaller(
+      code,
+      {dev: false},
+      {babelRuntimeModuleName: '@react-native/babel-runtime'},
+    );
+    expect(result).toContain(
+      '@react-native/babel-runtime/helpers/objectWithoutProperties',
+    );
+    expect(result).not.toContain('@babel/runtime/helpers');
+  });
+
+  it('options babelRuntimeModuleName takes precedence over caller', () => {
+    const code = 'const {a, ...rest} = obj;';
+    const result = transformWithCaller(
+      code,
+      {dev: false, babelRuntimeModuleName: '@from/options'},
+      {babelRuntimeModuleName: '@from/caller'},
+    );
+    expect(result).toContain('@from/options/helpers/objectWithoutProperties');
+    expect(result).not.toContain('@from/caller');
+  });
+
+  it('uses caller-provided enableBabelRuntime version to select the helper interop', () => {
+    // A default import triggers the `interopRequireDefault` helper, whose import
+    // form depends on the runtime version. Modern versions append `.default`.
+    const code = "import foo from './foo';\nfoo();";
+    const result = transformWithCaller(
+      code,
+      {dev: false},
+      {enableBabelRuntime: '7.25.0'},
+    );
+    expect(result).toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault").default',
+    );
+  });
+
+  it('options enableBabelRuntime takes precedence over caller', () => {
+    const code = "import foo from './foo';\nfoo();";
+    const result = transformWithCaller(
+      code,
+      {dev: false, enableBabelRuntime: '7.0.0'},
+      {enableBabelRuntime: '7.25.0'},
+    );
+    // Options version (7.0.0) uses the legacy interop form without `.default`,
+    // overriding the caller version (7.25.0) that would produce `.default`.
+    expect(result).toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault")',
+    );
+    expect(result).not.toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault").default',
+    );
+  });
+
+  it('has no effect when caller options are absent', () => {
+    const code = "import foo from './foo';\nfoo();";
+    const result = transformWithCaller(code, {dev: false}, {});
+    // Default runtime version uses the legacy interop form (no `.default`).
+    expect(result).toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault")',
+    );
+    expect(result).not.toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault").default',
+    );
+  });
+
+  it('does not add the runtime plugin when caller disables enableBabelRuntime', () => {
+    const code = 'const {a, ...rest} = obj;';
+    const result = transformWithCaller(
+      code,
+      {dev: false},
+      {
+        enableBabelRuntime: false,
+        babelRuntimeModuleName: '@react-native/babel-runtime',
+      },
+    );
+    expect(result).not.toContain('@react-native/babel-runtime');
+    expect(result).not.toContain('@babel/runtime/helpers');
+  });
+
+  it('options enableBabelRuntime false takes precedence over caller true', () => {
+    const code = 'const {a, ...rest} = obj;';
+    const result = transformWithCaller(
+      code,
+      {dev: false, enableBabelRuntime: false},
+      {enableBabelRuntime: '7.25.0'},
+    );
+    expect(result).not.toContain('@babel/runtime/helpers');
+  });
+});

packages/react-native-babel-preset/src/configs/main.js

@@ -40,10 +40,16 @@ function isFirstParty(fileName) {
   );
 }
 
-// Called by Babel whenever caller information changes between transform calls
-// for a given config. If the return value changes, Babel re-evaluates
-// getPreset, which is otherwise cached based on `options`. This must be pure,
-// and should be cheap.
+/**
+ * BEGIN BABEL CALLER GETTERS
+ * Called by Babel whenever caller information changes between transform calls
+ * for a given config. If the return value changes, Babel re-evaluates
+ * getPreset, which is otherwise cached based on `options`.
+ *
+ * These functions must be pure and should be cheap.
+ **/
+
+// Target transform profile, influencing which plugins are active
 function getTransformProfile(caller) {
   return caller?.unstable_transformProfile ?? 'hermes-stable';
 }
@@ -66,6 +72,20 @@ function getExperimentalImportSupport(caller) {
   return caller?.experimentalImportSupport ?? false;
 }
 
+// A boolean to toggle @babel/plugin-transform-runtime, or a string to pin
+// a specific @babel/runtime version.
+function getEnableBabelRuntime(caller) {
+  return caller?.enableBabelRuntime;
+}
+
+// Reads the caller-provided @babel/runtime module name that helpers are imported
+// from.
+function getBabelRuntimeModuleName(caller) {
+  return caller?.babelRuntimeModuleName;
+}
+
+/* END BABEL CALLER GETTERS */
+
 // use `this.foo = bar` instead of `this.defineProperty('foo', ...)`
 const loose = true;
 
@@ -248,16 +268,31 @@ const getPreset = (src, options, babel) => {
     ]);
   }
 
-  if (options.enableBabelRuntime !== false) {
-    // Allows configuring a specific runtime version to optimize output
-    const isVersion = typeof options.enableBabelRuntime === 'string';
+  // `enableBabelRuntime` (a boolean toggle or a string @babel/runtime version to
+  // pin) and `babelRuntimeModuleName` (the module helpers are imported from) may
+  // be provided via options or, for programmatic callers such as Metro, via
+  // Babel caller data. Options take precedence over caller data, consistent with
+  // the other options resolved here.
+  const enableBabelRuntime =
+    options.enableBabelRuntime ?? babel?.caller(getEnableBabelRuntime) ?? true;
+
+  if (enableBabelRuntime !== false) {
+    // A string value pins a specific runtime version to optimize output.
+    const isVersion = typeof enableBabelRuntime === 'string';
+
+    const babelRuntimeModuleName =
+      options.babelRuntimeModuleName ??
+      babel?.caller(getBabelRuntimeModuleName);
 
     extraPlugins.push([
       require('@babel/plugin-transform-runtime'),
       {
         helpers: true,
         regenerator: enableRegenerator,
-        ...(isVersion && {version: options.enableBabelRuntime}),
+        ...(isVersion && {version: enableBabelRuntime}),
+        ...(babelRuntimeModuleName != null && {
+          moduleName: babelRuntimeModuleName,
+        }),
       },
     ]);
   } else if (enableRegenerator) {