feat: concatenate CommonJS modules with statically analyzable exports

[JSerFeng]

Summary

• add the optimization.concatenateModules.commonjs option, which defaults to true when module concatenation is enabled
• concatenate strict CommonJS modules whose exports can be statically rewritten by hoisting exports.x / module.exports.x into concatenation-scope bindings
• apply the same safe CommonJS hoisting to modern-module ESM output without registering a module factory wrapper
• preserve live bindings, nested export assignments, namespace/default interop, and non-identifier export names
• keep factory-dependent or prototype-sensitive CommonJS modules wrapped, including top-level return, free arguments, delete exports.x, tagged-template call contexts, and exports.__proto__ / Object prototype access
• honor optimization.concatenateModules.commonjs: false in modern-module output
• port the upstream config cases and add ordinary and ESM output regression coverage

This ports webpack/webpack#21417. It intentionally does not include the IIFE wrapper behavior from webpack/webpack#21436.

Related links

• feat: concatenate CommonJS modules with statically analyzable exports webpack/webpack#21417
• feat: wrap non-hoistable CommonJS modules into module concatenation webpack/webpack#21436

Validation

• cargo check -p rspack_plugin_javascript -p rspack_plugin_esm_library -p rspack_plugin_library -p rspack_binding_api
• cargo test -p rspack --no-run
• cargo clippy -p rspack_plugin_javascript -p rspack_plugin_esm_library -p rspack_plugin_library -p rspack_binding_api --all-targets -- -D warnings
• cargo fmt --all -- --check
• corepack pnpm run build:cli:dev
• corepack pnpm run lint:js
• corepack pnpm --dir tests/rspack-test run test -t "concatenate-modules/" (50 passed)
• corepack pnpm exec rstest EsmOutput.test.js from tests/rspack-test (486 passed)
• corepack pnpm exec rstest StatsAPI.test.js -t "with-query" from tests/rspack-test

Checklist

• Tests updated.
• Documentation updated (configuration types).

[github-actions]

📦 Binary Size-limit

Comparing 3f2e2e3 to fix(binding): preserve entry dependency identity (#14964) by harpsealjs

❌ Size increased by 8.00KB from 66.74MB to 66.75MB (⬆️0.01%)

[github-actions]

Rsdoctor Bundle Diff Analysis

⚠️ Note: The latest commit (8859c6a442) does not have baseline artifacts. Using commit a7c0970a30 for baseline comparison instead. If this seems incorrect, please wait a few minutes and try rerunning the workflow.

Found 5 projects in monorepo, 2 projects with changes.

📊 Quick Summary

Project	Total Size	Gzip Size	Change	Gzip Change
popular-libs	1.7 MB	552.1 KB	0	0
react-10k	5.6 MB	1.3 MB	-	-
react-1k	823.1 KB	217.0 KB	0	0
react-5k	2.7 MB	663.8 KB	0	0
ui-components	4.9 MB	1.4 MB	+33.0 B (0.0%)	+106.0 B (0.0%)

📋 Detailed Reports (Click to expand)

📁 react-10k

Path: ../build-tools-performance/cases/react-10k/dist/rsdoctor-data.json

⚠️ No baseline data found - Unable to perform comparison analysis

Metric	Current	Baseline	Change
📊 Total Size	5.6 MB	-	-
🗜️ Gzip Size	1.3 MB	-	-
📄 JavaScript	5.6 MB	-	-
🎨 CSS	21.0 B	-	-
🌐 HTML	328.0 B	-	-
📁 Other Assets	0 B	-	-

📁 ui-components

Path: ../build-tools-performance/cases/ui-components/dist/rsdoctor-data.json

📌 Baseline Commit: a7c0970a30 | PR: #14964

Metric	Current	Baseline	Change
📊 Total Size	4.9 MB	4.9 MB	+33.0 B (0.0%)
🗜️ Gzip Size	1.4 MB	1.4 MB	+106.0 B (0.0%)
📄 JavaScript	4.8 MB	4.8 MB	+33.0 B (0.0%)
🎨 CSS	112.1 KB	112.1 KB	0
🌐 HTML	328.0 B	328.0 B	0
📁 Other Assets	0 B	0 B	0

📦 Download Diff Report: ui-components Bundle Diff

🤖 AI Degradation Analysis (Click to expand)

📊 Size Changes

No significant regressions detected 🎉. (Total bundle delta: +33 bytes / 0.0006%)

🔍 Root Cause Analysis

• @arco-design/web-react: Internal util modules (mergeProps, raf, throttleByRaf) increased marginally (+52 bytes parsed total).
• react-is: Minor increase in parsed size (720 → 745 bytes, +3.47%).
• @mui/utils: Negligible decrease (-12 bytes parsed) offsetting other changes.
• No new dependencies or large modules added.

⚠️ Risk Assessment

Overall severity: Low

• The total initial JS chunk increased by only 33 bytes (5,007,425 → 5,007,458), which is within standard build variance noise.

💡 Optimization Suggestions

1. Approve PR: No performance impact detected; safe to merge.
2. Monitor Arco Updates: Keep an eye on @arco-design/web-react changelogs if future updates show larger deltas.
3. Audit react-is: Ensure it remains a transitive dependency and isn't being directly imported unnecessarily.

_{Analysis by qwen3.5-plus}

Generated by Rsdoctor GitHub Action

[codspeed-hq]

Merging this PR will not alter performance

✅ 46 untouched benchmarks
⏩ 47 skipped benchmarks¹

---

_{Comparing codex/concatenate-commonjs-modules (3f2e2e3) with main (a7c0970)}

Footnotes

1. 47 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[cloudflare-workers-and-pages]

Deploying rspack with    Cloudflare Pages

Latest commit:	3f2e2e3
Status:	✅  Deploy successful!
Preview URL:	https://43acc189.rspack-v2.pages.dev
Branch Preview URL:	https://codex-concatenate-commonjs-m.rspack-v2.pages.dev

View logs

[hai-x]

Additional PRs in webpack:

1. refactor: wrapped CommonJS concatenated modules webpack/webpack#21464
2. feat: wrap concatenated ESM/CJS and inline CJS require edges webpack/webpack#21519