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…caller Summary: Follow-up to 8388f71 (the default `metro:` scheme resolver), which maps `metro:babel-runtime/<path>` to metro-runtime's own `@babel/runtime` dependency. This diff is the Metro half of pointing `@babel/plugin-transform-runtime` at it. When `transformer.enableBabelRuntime` is literally `true` (the default), the transform worker passes the Babel transformer `babelRuntimeModuleName: 'metro:babel-runtime'` and `babelRuntimeVersion` - the installed version of that `@babel/runtime`. `metro-babel-transformer` forwards them to presets as Babel caller data, as `babelRuntimeModuleName` and `enableBabelRuntime` respectively, matching what `@react-native/babel-preset` reads from react/react-native#57974. Caller data reaches a preset however it's configured - including via a project `babel.config.js`, where the preset's options come from the user. The version is read from the installed `package.json` rather than pinned to metro-runtime's range floor, so output benefits from runtime updates without a manual sync. Because that makes transform output depend on it, the `package.json` is added to the transform worker's cache key when `enableBabelRuntime` is `true`. A string `enableBabelRuntime` keeps its current meaning (a version for the project's own `@babel/runtime`) and passes neither value. It's now documented as deprecated in favour of `true`, since a version describing the project's copy is meaningless once helpers come from Metro's. The lookup of metro-runtime's `@babel/runtime` moves from `metroSchemeResolver` into a shared `metro/private/lib/metroBabelRuntime`, so the resolver and the worker agree on the same copy. This is a no-op until a preset reads it. Changelog: ``` - **[Feature]**: When `transformer.enableBabelRuntime` is `true`, pass Metro's own `@babel/runtime` (`metro:babel-runtime`) and its installed version to Babel presets via caller data - **[Deprecated]**: String values of `transformer.enableBabelRuntime` (use `true`) ``` Test plan: New integration test (`integration_tests/__tests__/babel-runtime-test.js`) builds and executes a bundle through the full Metro + Babel pipeline with Metro's own `metro-babel-transformer`, and a fixture `babel.config.js` whose preset reads `@babel/runtime` configuration from caller data, as `@react-native/babel-preset` does. The fixture uses `import * as`, whose `interopRequireWildcard` helper is only available from `@babel/runtime` 7.14.0, so it's imported rather than inlined only if the installed version reaches the preset: - With `enableBabelRuntime: true`, the bundle imports `metro:babel-runtime/helpers/interopRequireWildcard`, which resolves to metro-runtime's own `@babel/runtime`, and executes correctly. - With `enableBabelRuntime: false`, the helper is inlined, and the bundle executes correctly. ``` yarn jest packages/metro/src/integration_tests packages/metro-transform-worker packages/metro-babel-transformer packages/metro/src/lib yarn flow check yarn build-ts-defs && yarn verify-api-snapshots yarn typecheck-ts ```
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Follow-up to 8388f71 (the default
metro:scheme resolver), which mapsmetro:babel-runtime/<path>to metro-runtime's own@babel/runtime. This is the Metro half of pointing@babel/plugin-transform-runtimeat it. The preset half is react/react-native#57974, and this is a no-op until a preset reads it.When
transformer.enableBabelRuntimeistrue(the default), Metro passes presetsbabelRuntimeModuleName: 'metro:babel-runtime'and the installed version of that@babel/runtimeas Babel caller data, matching what@react-native/babel-presetreads. Caller data reaches a preset however it's configured, including via a projectbabel.config.js.The version is read from the installed package rather than pinned, so it's added to the transform cache key. A string
enableBabelRuntime(a version for the project's own@babel/runtime) keeps its meaning and passes neither value. It's now documented as deprecated, since a version describing the project's copy is meaningless once helpers come from Metro's.Changelog:
Test plan:
New integration test builds and runs a bundle through the full Metro + Babel pipeline, with a preset that reads the caller data as
@react-native/babel-presetdoes. The fixture usesimport * as, whose helper is only external from@babel/runtime7.14.0, so it's imported rather than inlined only if the version reaches the preset. Verified withenableBabelRuntimebothtrueandfalse.