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fix(core): Mark package as side-effect free - #6829
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LGTM 🎉 Thank you for your contribution 🙇
Verified this is safe to mark side-effect free:
- Tree-shaking confirmed — reproduced the issue's esbuild setup: import { SDK_VERSION } drops from ~86 KB / 119 input files down to a couple hundred bytes / 2 files with the flag applied. Matches the
expected result in the issue. - No import-time side effects — audited everything reachable from index.ts (excluding Node-only tools/): no bare side-effect imports, no top-level global patching/polyfills/registration. The
Promise/encode polyfills and all native/global touches run inside init()/wrap()/integration factories, so false (not a module allowlist) is the correct choice — consistent with @sentry/core,
@sentry/browser and @sentry/react. - No API/behavior change — package metadata only; default Metro builds are unaffected, tree-shaking bundlers (Rollup/webpack/esbuild/Expo) get the win.
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…6836) * ci(core): Guard the "sideEffects": false contract with a lint check PR #6829 marked @sentry/react-native as side-effect free so bundlers can tree-shake unused exports. That flag is an unguarded, package-wide promise: if any shipped module ever runs code at import time, a bundler may drop it when its exports are unused, silently breaking the SDK in consumer bundles. Add scripts/check-side-effects.js, wired into `yarn lint`, which scans src/js (excluding Node-only tools/) and fails if a module has an import-time side effect: a bare side-effect import, or a top-level executed statement (call, assignment, IIFE, global write). Declarations are allowed. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> * ci(core): Harden side-effect scan against wrapped statements Review feedback (Seer + Cursor Bugbot): the scan only flagged top-level ExpressionStatements and clause-less imports, so a side effect wrapped in an `if`/`for`/`while`/`try`/block — or an empty-binding `import {} from 'x'` — slipped through while the lint stayed green. Invert to an allowlist: permit only pure declarations at module top level (function/class/interface/type/enum/namespace/variable/export/import-equals), flag every other statement, and treat an import that binds nothing (incl. `import {} from 'x'`) as a side-effect import. Type-only imports are erased, so they're allowed. Exclude `vendor/` (audited third-party code) alongside `tools/`, so the guard targets first-party SDK code. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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📢 Type of change
📜 Description
Adds
"sideEffects": falseto@sentry/react-native's package.json, same as@sentry/core,@sentry/reactand@sentry/browseralready have.I grepped
src/jsfor anything that runs at import time. The only top-level calls are insrc/js/tools/(metro config, babel transformer, collect-modules script), and those get loaded by Node directly, never bundled into the app. Nothing else patches globals on import.💡 Motivation and Context
Fixes getsentry/sentry#126410. Without the flag, importing even just
SDK_VERSIONdrags most of the SDK into the bundle with esbuild/Rollup/webpack (and Expo's tree shaking).💚 How did you test it?
Ran the repro from the issue against the published 8.29.0, with and without the flag patched into its package.json (I also had to mark
promise/*as external):📝 Checklist
sendDefaultPIIis enabled.🔮 Next steps