Conversation
…dule types Summary: `flow-api-translator` 0.332.0 translates `declare module.exports` to TypeScript's `export =` (facebook/flow#9491). Until now `scripts/generateTypeScriptDefinitions.js` rejected any module whose Flow def used it, which is why all of `metro-runtime` bar `modules/types.js` was excluded, and why most of our hand-maintained `src/**/*.d.ts` overrides exist. This diff bumps `flow-api-translator`, `flow-eslint` and `flow-parser` to 0.333.0, matching `flow-bin`, drops the `module.exports` rejection and the `metro-runtime` exclusion, and removes as many overrides as the translator can now replace: - `metro-runtime` is generated like any other package - `asyncRequire`, `HMRClient`, `null-module` and `polyfills/require` gain types and API snapshots. - Eight overrides go: `metro-minify-terser` and `metro-symbolicate` (generated output is equivalent), the five CommonJS worker and extractor modules in `metro-file-map`, and `metro-file-map/src/lib/dependencyExtractor.d.ts`, which had no `.js` beside it and so was never used. - Two stay: `metro-transform-plugins/src/index.d.ts`, because it combines `export type` with `module.exports`, which TypeScript can't express as `export =` without namespace merging; and `crawlers/watchman/planQuery.d.ts`, because the generated output imports types from `fb-watchman`, which has none. Getting there needed a few changes to the generator and to Flow sources, none of which affect runtime behaviour: - Flow comment types (`/*: T */`, `/*:: ... */`) are expanded before translation. The `metro-file-map` workers are loaded in Node without Babel and are typed that way, so the translator saw no annotations at all and emitted `any`. - A `.js.flow` file is used as the Flow source for the adjacent `.js`. That's Flow's own convention, and it types the vendored `eventemitter3` (no `@flow` directive) without an override. - `lintText` returns no result for a path `.eslintignore` covers (`**/vendor/**`), so the generator tolerates that and leaves the output unlinted. - The two `metro-file-map` plugin workers now declare their class and export it by name, rather than exporting an anonymous class expression, which `flowToFlowDef` can't type. - `asyncRequire` exports through an `as AsyncRequire` cast - `flowToFlowDef` drops statics assigned to a function, so `prefetch` and `unstable_importMaybeSync` were otherwise lost. The cast is type-only, and `metro-runtime` already uses `as` casts elsewhere. - `HMRClient._heartbeatTimer` is typed `?ReturnType<typeof setInterval>` in place of Flow's `IntervalID` global, which the translator passes through and TypeScript has no name for. - Generated `.d.ts` no longer run `@typescript-eslint`'s `no-explicit-any` or `no-unused-vars`. Flow checks the sources these are translated from, and an `any` in the output reflects one there; the second rule reports a declaration a CommonJS module exports via `typeof` as unused, which is most of what `metro-runtime` and the `metro-file-map` workers now emit. `no-unused-vars` stays on in the generator's own `--fix` pass, which uses it to drop declarations left unused by translation. `no-empty-object-type` is off too, for now: Flow's inexact `{...}` translates to `{}`, which the rule flags in `polyfills/require.d.ts` - the follow-up diff fixes those annotations at source and turns the rule back on. This replaces the per-file exemption for `metro-file-map/types/flow-types.d.ts`. - `generateApiSnapshots.js` snapshots `export =` entry points properly. API Extractor ignores `export =` entirely (`ExportAnalyzer` skips `ts.InternalSymbolName.ExportEquals`), which is why `metro-minify-terser` and `metro-transform-plugins` had empty `API.md` files. For extraction only, those entry points now go through a temporary copy of their `.d.ts` that uses `export default`, exports its local declarations (in an `export =` module every type is local, and a report shows only exports), and imports other `export =` modules with `import x = require()` - a default import of one throws inside API Extractor. The published `.d.ts` keep `export =`. Separately, a report that still comes out empty is no longer written, stale ones are deleted, and `--verify` fails if one is checked in. Changelog: ``` - **[Types]**: Add TypeScript definitions for `metro-runtime` modules, and generate (rather than hand-maintain) types for `metro-file-map` workers ``` Test plan: ``` yarn flow check yarn typecheck-ts yarn build-api-snapshots yarn verify-api-snapshots yarn jest ``` Flow and `tsc` are clean. API snapshots for ES module entry points are unchanged, so removing the overrides changes no public API. `metro-minify-terser` and `metro-transform-plugins` gain real snapshots in place of empty ones, and `metro-runtime` gains four. Jest: all 150 suites pass, including the `metro` integration tests, which bundle `metro-runtime`.
meta-cla
Bot
added
the
CLA Signed
facebook-github-tools
Bot
added
the
Shared with Meta
robhogan
added a commit
that referenced
this pull request
Sep 28, 2026
API Extractor ignores `export =`, so any entry point whose `.d.ts` uses it gets an empty API report. Currently that's `metro-minify-terser` and `metro-transform-plugins`, whose hand-written definitions both end in `export =`: https://github.com/react/metro/blob/b7c20552a16a251507f753c3da23cc7d18488b6c/packages/metro-minify-terser/src/index.d.ts#L11-L14 Once #1977 generates definitions for CommonJS modules, it'll be all of those too. This works around it for extraction only. API Extractor gets a temporary copy of the `.d.ts` that uses `export default` in place of `export =` and exports the module's local types, so they show up in the report. Published definitions keep `export =`. The copy is made by parsing the `.d.ts` with Babel and editing its text in place, so comments and formatting carry through to the report. An entry point with nothing to report now gets no `API.md` rather than an empty one, and `--verify` fails on a stale one. Changelog: Internal Test plan: `yarn run build-api-snapshots` fills in the `metro-minify-terser` and `metro-transform-plugins` reports and leaves the other 12 unchanged. The new `metro-runtime` reports in #1977 come from the same change.
Collaborator
Author
|
Superseded by #1996 |
robhogan
added a commit
that referenced
this pull request
Sep 29, 2026
API Extractor ignores `export =`, so any entry point whose `.d.ts` uses it gets an empty API report. Currently that's `metro-minify-terser` and `metro-transform-plugins`, whose hand-written definitions both end in `export =`: https://github.com/react/metro/blob/b7c20552a16a251507f753c3da23cc7d18488b6c/packages/metro-minify-terser/src/index.d.ts#L11-L14 Once #1977 generates definitions for CommonJS modules, it'll be all of those too. This works around it for extraction only. API Extractor gets a temporary copy of the `.d.ts` that uses `export default` in place of `export =` and exports the module's local types, so they show up in the report. Published definitions keep `export =`. The copy is made by parsing the `.d.ts` with Babel and editing its text in place, so comments and formatting carry through to the report. An entry point with nothing to report now gets no `API.md` rather than an empty one, and `--verify` fails on a stale one. Changelog: Internal Test plan: `yarn run build-api-snapshots` fills in the `metro-minify-terser` and `metro-transform-plugins` reports and leaves the other 12 unchanged. The new `metro-runtime` reports in #1977 come from the same change.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary:
flow-api-translator0.332.0 translatesdeclare module.exportsto TypeScript'sexport =(facebook/flow#9491). Until nowscripts/generateTypeScriptDefinitions.jsrejected any module whose Flow def used it, which is why all ofmetro-runtimebarmodules/types.jswas excluded, and why most of our hand-maintainedsrc/**/*.d.tsoverrides exist.This:
flow-libs to0.333.0, matchingflow-bingenerateApiSnapshotsignore listIntervalIDdoesn't exist in TS, but we can useReturnType<typeof setInverval>.flow-parserWASM drops Flotate).js.flowof an untyped.jsas the basis for.d.ts(vendoredeventemitter3)export =isexport default, otherwise it sees nothing..d.tsoverrides.@typescript-eslint:no-unused-vars- an artifact offlow-api-translator's output and although it's possible write Flow that works around it, it shouldn't be a concern for Flow authors.no-explicit-any- if these appear, it's because we've already suppressed equivalents in Flow - respect that.no-empty-object-type- this is more legitimate, it's re-enabled in a follow-up with better types forrequire.jsChangelog:
Test plan:
CI
.d.tslocally (they're gitignored) and inspect the output