preserve require.context call when unstable_disableModuleWrapping is enabled #1129
Conversation
This file contains 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
facebook-github-bot
added
the
CLA Signed
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## main #1129 +/- ##
=======================================
Coverage 83.09% 83.09%
=======================================
Files 206 206
Lines 10547 10548 +1
Branches 2617 2618 +1
=======================================
+ Hits 8764 8765 +1
Misses 1783 1783
☔ View full report in Codecov by Sentry. |
facebook-github-bot
added
the
Shared with Meta
This was referenced Jul 1, 2024
EvanBacon
added a commit
to expo/expo
that referenced
this pull request
Jul 3, 2024
…ns (#30140) # Why - The dependency collection system needs extra customizations for tree shaking (tracking more import info, not mutating require context, etc.) and for supporting SSR externals (required for RSC). - Will pull in proposed changes such as facebook/metro#1129 in the future. <!-- Please describe the motivation for this PR, and link to relevant GitHub issues, forums posts, or feature requests. --> # How - Have ChatGPT rewrite the upstream collect dependencies module and tests in TypeScript. - No extra changes are applied on top of the module. # Test Plan - Pulled in the upstream tests to ensure compat with Metro. --------- Co-authored-by: Expo Bot <34669131+expo-bot@users.noreply.github.com>
EvanBacon
added a commit
to expo/expo
that referenced
this pull request
Jul 23, 2024
# Why > Most of the original PR has been landed in #30417 - Metro bundler does not have any form of graph-wide tree shaking built-in. This can lead to bundle sizes that are larger than they need to be, especially in the case of icon libraries. - This PR (which is partially an RFC) aims to add a system for removing unused imports and exports from a production bundle. <!-- Please describe the motivation for this PR, and link to relevant GitHub issues, forums posts, or feature requests. --> # How - Leverage the new "optimize graph" mode to perform holistic optimizations in the serializer. #30417 - Tree shaking can be enabled with the new env var `EXPO_UNSTABLE_TREE_SHAKING=1`. - This PR also adds a "barrel expansion" system which attempts to replace `export * from '...'` statements with `export { View, Image, etc } from '...'` statements to enable more graph reduction. - Empty modules (containing only comments and directives) are removed from the bundle. - Side-effecty imports (imports with zero specifiers, `import "foo"` and `import {} from "foo"`) are preserved unless marked otherwise by a `package.json`'s `sideEffects` field. - Custom imports such as `require.context` and `require.resolveWeak` are left in place. - Removed exports with source will trigger a recrawl to ensure any new unused imports/exports are recursively removed. - The feature is artificially forced to only run when `EXPO_UNSTABLE_TREE_SHAKING=1` is set, and when bundling for production. Tree shaking is disabled for SSR bundles. I may expand this to be web-only too just due to a lack of continuous testing for native runtimes. - Added some external fixes software-mansion/react-native-reanimated#6171 #30010 #29980 #29964 #29963 software-mansion/react-native-gesture-handler#2972 # Further work Some ideas that I've had but aren't implemented in this PR: - Use the worker farm to parallelize transformation in the serializer. This could be tricky because we'd need to convert the AST to a serial format then re-parse it back. - ~~Fork collectDependencies to fully track the import/exports so we can reuse the same import crawling code and references. This would also speed up the bundling as we could parallelize and cache the pass.~~ #30140 - Use a totally custom syntax for matching import/exports, e.g. `_$$_IMPORT_DEFAULT, _$$_IMPORT_ALL` (and some new export equivalents) to reduce the number of transforms we run in the serializer. All import/export's and the iife wrap could be run at transform-time and we'd simply be mutating a valid JS bundle in the serializer. This would be very challenging though and make it harder for users to contribute to the implementation. - ~~Upstream the hack on transformSyncRequire to support require.context with one parameter. facebook/metro#1129 - Detect if a module is CJS according to Node.js heuristic, e.g. `.cjs`, package exports, etc. then opt it out of tree shaking. - [ ] update source maps # Test Plan - Added an e2e tree shaking test for web. - Added mini-metro tests to account for the known and expected tree shaking behaviors. - Added mini-metro tests for side-effect handling (need more here). - Ensured all apps in expo/apps can be transformed and run with tree shaking enabled. --------- Co-authored-by: Expo Bot <34669131+expo-bot@users.noreply.github.com> Co-authored-by: Aman Mittal <amandeepmittal@live.com>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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
One possible way to implement tree shaking would require calling collectDependencies with
unstable_disableModuleWrappingfor a first pass, and invoking it a second time with module wrapping. The issue with this is that the require.context mutation is mutated to a format that wouldn't work on subsequent runs.This PR will prevent the additional mutation of
require.context->require.Test plan
Tests continue working