[0.87.0] VirtualizedList triggers Metro package-exports warning #57933

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1. wojtekmaj

   added

   Needs: Triage 🔍

   on Aug 13, 2026
2. wojtekmaj

   changed the title [-][0.87.0] @react-native/virtualized-lists triggers Metro package-exports warning for ReactNativeFeatureFlags[/-] [+][0.87.0] VirtualizedList triggers Metro package-exports warning[/+] on Aug 13, 2026
3. brentvatne commented on Aug 26, 2026

   

   brentvatne

   on Aug 26, 2026 · Hidden as outdated

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4. expo-bot commented on Aug 26, 2026

   

   expo-bot

   on Aug 26, 2026

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   Proposed fix — 1 file, 15 diff lines. This patch was produced by the verification run for #57933 (requested by @brentvatne) and has not been run through this repository's CI; treat it as a starting point for a maintainer, not a landed change.

   Export the ReactNativeFeatureFlags subpath used by @react-native/virtualized-lists

   Summary:

   A fresh React Native 0.87.0 app that renders the public FlatList API makes Metro print a package-exports warning, reported in #57933:

    WARN  Attempted to import the module ".../node_modules/react-native/src/private/featureflags/ReactNativeFeatureFlags" which is not listed in the "exports" of ".../node_modules/react-native" under the requested subpath "./src/private/featureflags/ReactNativeFeatureFlags". Falling back to file-based resolution.
   

   @react-native/virtualized-lists is a separate npm package. It reaches React Native only through the react-native package exports map, and it imports react-native/src/private/featureflags/ReactNativeFeatureFlags in two shipped files — Lists/VirtualizedList.js#L67 and Lists/VirtualizeUtils.js#L16 — plus one test file, Lists/__tests__/VirtualizeUtils-test.js#L21. It reads the JS-only flags deferFlatListFocusChangeRenderUpdate and fixVirtualizeListCollapseWindowSize.

   #57484 (commit f0bb9de) removed the "./src/*" mapping from packages/react-native/package.json. The summary of that pull request says these import paths "were never used externally", and its one listed caveat is rn-tester. The cross-package import from @react-native/virtualized-lists was missed, so the subpath became unlisted while both call sites stayed. FlatList, SectionList and VirtualizedList all load VirtualizedList.js, so any app that renders a list hits the warning.

   This change adds back that one exact subpath. It does not restore the "./src/*" wildcard.

   Nothing breaks at runtime today, because Metro falls back to file-based resolution. The cost is a warning on every bundle of an app that uses a core public component, and a dependence on a resolver fallback that stricter resolvers do not provide.

   Changelog:

   [GENERAL] [FIXED] - Fix Metro package-exports warning when rendering FlatList, by exporting the react-native/src/private/featureflags/ReactNativeFeatureFlags subpath that @react-native/virtualized-lists imports

   Test Plan:

   Reproducer from #57933, unmodified, on Node 24.19.0 and yarn 1.22.22 (Linux):

   git clone https://github.com/wojtekmaj/react-native-087-virtualized-lists-exports-repro.git
   cd react-native-087-virtualized-lists-exports-repro/ReproducerApp
   yarn install --frozen-lockfile     # react-native 0.87.0, @react-native/virtualized-lists 0.87.0, metro 0.87.0
   npx react-native bundle --reset-cache --platform ios --dev true --entry-file index.js \
     --bundle-output out.jsbundle --assets-dest out-assets
   

   The only variable between the runs below is the four added lines, applied to node_modules/react-native/package.json in that app. All four arms used --reset-cache.

   Platform	exports entry	Warning lines	Bundle size	Bundle md5
   iOS	absent	1	4056458	d5a5f226c40d8ae791bfc79022b3bfe6
   iOS	present	0	4056458	d5a5f226c40d8ae791bfc79022b3bfe6
   Android	absent	1	4072414	d7fe9c93b2399e101f4eae44b06faec1
   Android	present	0	4072414	d7fe9c93b2399e101f4eae44b06faec1

   On each platform the two bundles are byte-identical. The change removes the warning and does not change what Metro resolves.

   Repository checks, run in a clean checkout of main at ea06a31 with the change applied:

   • npx prettier --check packages/react-native/package.json — All matched files use Prettier code style!
   • yarn jest packages/virtualized-lists — 8 suites passed, 172 passed / 1 skipped, 69 snapshots passed
   • yarn flow-check — Found 0 errors
   • yarn test — 224 suites passed, 5845 passed / 1 skipped, 1681 snapshots passed

   scripts/build/build.js is the only tool in the repository that reads an exports map, and it validates only packages listed in scripts/build/config.js. react-native is not one of them, so the new entry needs no .flow.js wrapper.

   Options considered

   1. Add the single exact subpath "./src/private/featureflags/ReactNativeFeatureFlags" to the exports map. Chosen: it is four lines, it changes no resolution result (byte-identical bundles above), it keeps the "./src/*" wildcard removed, and it also covers third-party code that follows the import path documented in src/private/featureflags/__docs__/README.md.
   2. Restore the "./src/*" wildcard that Remove src/* exports mapping (#57484) #57484 removed. Cost: it re-lists every file under src/, including all of src/private/, as a package entry point. That is the exact mapping Remove src/* exports mapping (#57484) #57484 set out to delete. Rejected: it reverts a deliberate change instead of correcting one missed call site.
   3. Add a dedicated private entry point for first-party packages, in the style of ./react-private-interface. Cost: one new source file in packages/react-native/src, a new exports entry, and three changed import sites in packages/virtualized-lists. It also leaves the documented import path unlisted for everyone else. Rejected: choosing the name and the scope of a new entry point is a design decision for the maintainers.
   4. Do nothing and document the behaviour. Cost: every bundle of every app that renders FlatList, SectionList or VirtualizedList keeps printing the warning, and correct resolution keeps depending on the Metro fallback. Rejected: the warning names an internal path that the app author cannot act on.

   Patch (packages/react-native/package.json)

   diff --git a/packages/react-native/package.json b/packages/react-native/package.json
   index 6d0af84..9c03f9d 100644
   --- a/packages/react-native/package.json
   +++ b/packages/react-native/package.json
   @@ -59,6 +59,10 @@
          "types": null,
          "default": "./src/unstable-internals-do-not-use.js"
        },
   +    "./src/private/featureflags/ReactNativeFeatureFlags": {
   +      "types": null,
   +      "default": "./src/private/featureflags/ReactNativeFeatureFlags.js"
   +    },
        "./src/fb_internal/*": "./src/fb_internal/*",
        "./package.json": "./package.json"
      },
   

   _{Run: (no run url)}
5. meta-codesync

   closed this as completedin a506ed6on Sep 8, 2026
6. rubennorte

   added a commit that references this issue on Sep 8, 2026

   Expose ReactNativeFeatureFlags through react-private-interface (react…

   ...

   a506ed6
7. shashikant-panchal

   added a commit that references this issue on Sep 10, 2026

   Expose ReactNativeFeatureFlags through react-private-interface (react…

   ...

   9af6844
8. fabriziocucci

   added a commit that references this issue on Sep 24, 2026

   Expose ReactNativeFeatureFlags through react-private-interface (#57940)

   ...

   6532c25
9. tvinhas

   added a commit that references this issue on Oct 21, 2026

   Expose ReactNativeFeatureFlags through react-private-interface (react…

   ...

   f5d1835