fix(codegen): skip node_modules and symlinks when crawling for components

[gabrieldonadel]

Summary:

findFilesWithExtension walks a library's directory looking for .mm files that declare a Fabric component. The walk descends into every subdirectory, node_modules included, resolves symlinks through statSync, and keeps no visited set.

This got broken after #57790 because parseiOSAnnotations now enters every library that declares a codegenConfig without an ios key into its map with an empty components object, so nothing removes it from librariesToCrawl. Previously such libraries were filtered before crawling.

An app that declares codegenConfig with "type": "all" and no ios key now gets treated as a component library, so the walk covers the entire project.

What we notice in the expo repo is that under pnpm, the traversal never terminates. Workspace packages link into each other's node_modules and form cycles. Because symlinks are followed, the walk only stops once paths hit the 1023 byte limit. CocoaPods progress stops right after the "Using React Native Core and React Native Dependencies prebuilt versions" line while a generate-codegen-artifacts.js child sits at 100% CPU.

Under npm and yarn, the walk completes but with the wrong result. In those cases, node_modules holds real directories, but the walk covers the whole dependency tree. Crawling one app of roughly 1100 packages turned up 382 .mm files, 43 of which declare a component, among them React core views such as RCTImageComponentView and RCTScrollViewComponentView from react-native-macos. Each one is written into the app's entry in RCTThirdPartyComponentsProvider.mm. The existing /react-native/ path filter does not exclude them, since it requires a trailing separator and react-native-macos has none.

Changelog:

[IOS] [FIXED] - Codegen no longer crawls node_modules or follows symlinks when discovering components

Test Plan:

Two cases added to packages/react-native/scripts/codegen/__tests__/generate-artifacts-executor-test.js. The three existing findFilesWithExtension mocks move from statSync to lstatSync.

The symlink case builds a link pointing back at its own parent, so the pre-fix walk never terminates.

Negative control: with the generateRCTThirdPartyComponents.js change reverted and the tests left in place, both new cases fail. All 24 existing snapshots pass unchanged, so the change is additive for projects that already declare an ios config.

Measured by crawling the app directory of two real projects:

Project	Before	After
apps/bare-expo, pnpm	116,800 reads in 30s, still running	34 files, 1.1s
yarn app, ~1100 packages	382 files, 5.8s	8 files, 0.3s

[meta-codesync]

@vzaidman has imported this pull request. If you are a Meta employee, you can view this in D120122552.

[meta-codesync]

@vzaidman merged this pull request in 39751d8.