[Flight] Guard __webpack_get_script_filename__ for non-Webpack bundlers - #37365
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[Flight] Guard __webpack_get_script_filename__ for non-Webpack bundlers#37365koreahghg wants to merge 1 commit into
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addChunkDebugInfo called __webpack_get_script_filename__ unconditionally to collect DEV-only chunk debug info. Real Webpack compiles this identifier into a reference to __webpack_require__.u, but bundlers that only emulate the classic Webpack runtime (e.g. Metro) don't define it, so any DEV build throws a ReferenceError the first time a Suspense boundary resolves a client reference with chunks (fixes react#37038). Fall back to __webpack_require__.u, the primitive this call already compiles down to under real Webpack, when the newer global is absent.
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Summary
Fixes #37038.
addChunkDebugInfoinReactFlightClientConfigBundlerWebpackBrowser.jscalls__webpack_get_script_filename__(chunkId)unconditionally to collect DEV-only chunk debug/IO info. Real Webpack compiles this identifier into a constant-folded reference to__webpack_require__.u(see Webpack'sAPIPlugin), so it's effectively free there. Bundlers that only emulate the classic Webpack runtime APIs (e.g. Metro, used by Expo) implement__webpack_require__,__webpack_chunk_load__, and__webpack_require__.u, but never define this newer global, so any DEV build throwsReferenceError: Property '__webpack_get_script_filename__' doesn't existthe first time a Suspense boundary resolves a Server Function / client reference with chunks.This is DEV-only (the call is skipped entirely when
!__DEV__), so production builds are unaffected, but it breaks Metro's dev bundle outright.This change guards the call with a
typeofcheck and falls back to__webpack_require__.u(chunkId)— the exact primitive__webpack_get_script_filename__compiles down to under real Webpack, and one this same file already relies on elsewhere (thewebpackGetChunkFilenamepatch a few lines up).How did you test this change?
ReactFlightClientConfigBundlerWebpackBrowser-test.jswith two tests: one simulating a Metro-like environment (__webpack_require__.udefined,__webpack_get_script_filename__absent) assertingaddChunkDebugInfono longer throws and resolves the filename via the fallback; one confirming the real-Webpack global is still preferred when present.ReferenceErroragainst the pre-fix code, and passes after the fix.node ./scripts/prettier/index.js write-changed— clean.node ./scripts/tasks/linc.js— clean.dom-browseranddom-node-webpackrenderers — no errors.node ./scripts/jest/jest-cli.js ReactFlightClientConfigBundlerWebpackBrowser(dev and--prod) — pass; correctly gated out (@gate __DEV__) under--prod.ReactFlightDOMBrowser(60 tests) andreact-server-dom-webpacksuites — same pass/fail counts before and after this change (remaining failures are pre-existing, environment-specific: Windows path separators in a snapshot, and an unrelatedAbortSignal.anyrealm mismatch — confirmed identical on unmodifiedmain).www-classicandwww-modernrelease channels — pass.