Bug: Inaccurate Bundle Type Filtering in Rollup Build #29614

React version: 18.x.x up to latest

Steps To Reproduce

1. Clone the React repository.

2. Run: yarn install

3. Run either:

   • yarn build-for-devtools-dev
   • yarn build-for-devtools-prod

4. Observe the output of the shouldSkipBundle function logs within the build.js script.

Link to code example:

• Relevant code: scripts/rollup/build.js
• Relevant function: shouldSkipBundle

The current behavior:

The shouldSkipBundle function, responsible for determining whether to include a bundle in the build output, contains incorrect logic for filtering when multiple bundle types are specified. Specifically, the following line causes the issue:

  const isAskingForDifferentType = requestedBundleTypes.every(
    requestedType => bundleType.indexOf(requestedType) === -1
  );

This code uses Array.prototype.every with indexOf to check if all requested bundle types are missing in the current bundle type. However, when multiple types are specified, it should skip a bundle only if none of the requested types are present.

Here's an example of the incorrect behavior observed during debugging:

requestedBundleTypes [ 'NODE', 'NODE_DEV' ]
bundleType NODE_DEV
isAskingForDifferentType false

requestedBundleTypes [ 'NODE', 'NODE_DEV' ]
bundleType NODE_PROD
isAskingForDifferentType false // Incorrect behavior

In this case, even though the bundleType is NODE_PROD and doesn't include NODE_DEV, isAskingForDifferentType is incorrectly evaluated as false, leading to the bundle not being skipped.

The expected behavior:

The shouldSkipBundle function should correctly filter bundles based on multiple requested types. In the example above, the expected behavior is that isAskingForDifferentType should be true for the NODE_PROD bundle type, as it does not include the NODE_DEV type.

In general, the function should return true (skip the bundle) only if none of the requested types are included in the current bundle type.