Native dead returns and unused bindings removal transformers

[OscarCookeAbbott]

Motivation

This is an initial, successful version of some dead code elimination transformers to replace Babel transformers in Jira SSR.

The transformers successfully replace the Babel original's functionally (successful build and SSR render) but is likely to see a small followup PR in future to get the output aesthetically as close to 1:1 as possible (less comment removal/addition, perhaps some other small changes).

All new functionality is opt-in via env config as with my previous transformers, so they will not adversely affect any other projects.

Changes

• Implement new dead_returns_remover transformer and hook up via opt-in flag
• Implement new unused_bindings_remover transformer and hook up via opt-in flag

Checklist

• Existing or new tests cover this change
• There is a changeset for this change, or one is not required
• Added documentation for any new features to the docs/ folder

[changeset-bot]

🦋 Changeset detected

Latest commit: 6724864

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 75 packages

Name	Type
@atlaspack/transformer-js	Minor
@atlaspack/rust	Minor
@atlaspack/config-default	Patch
atlaspack	Patch
@atlaspack/bundler-experimental	Patch
@atlaspack/bundler-default	Patch
@atlaspack/cache	Patch
@atlaspack/core	Patch
@atlaspack/fs	Patch
@atlaspack/logger	Patch
@atlaspack/utils	Patch
@atlaspack/link	Patch
@atlaspack/optimizer-image	Patch
@atlaspack/optimizer-inline-requires	Patch
@atlaspack/packager-js	Patch
@atlaspack/transformer-compiled-css-in-js	Patch
@atlaspack/transformer-html	Patch
@atlaspack/transformer-postcss	Patch
@atlaspack/transformer-svg	Patch
@atlaspack/transformer-tokens	Patch
@atlaspack/node-resolver-core	Patch
@atlaspack/config-webextension	Patch
@atlaspack/cli	Patch
@atlaspack/register	Patch
@atlaspack/test-utils	Patch
@atlaspack/inspector	Patch
@atlaspack/query	Patch
@atlaspack/bundle-stats	Patch
@atlaspack/reporter-bundle-stats	Patch
@atlaspack/transformer-image	Patch
@atlaspack/inspector-frontend	Patch
@atlaspack/package-manager	Patch
@atlaspack/workers	Patch
@atlaspack/watcher-watchman-js	Patch
@atlaspack/optimizer-blob-url	Patch
@atlaspack/optimizer-css	Patch
@atlaspack/optimizer-data-url	Patch
@atlaspack/optimizer-svgo	Patch
@atlaspack/optimizer-swc	Patch
@atlaspack/optimizer-terser	Patch
@atlaspack/packager-css	Patch
@atlaspack/packager-html	Patch
@atlaspack/packager-raw-url	Patch
@atlaspack/packager-svg	Patch
@atlaspack/packager-webextension	Patch
@atlaspack/packager-xml	Patch
@atlaspack/reporter-build-metrics	Patch
@atlaspack/reporter-bundle-analyzer	Patch
@atlaspack/reporter-cli	Patch
@atlaspack/reporter-dev-server-sw	Patch
@atlaspack/reporter-dev-server	Patch
@atlaspack/reporter-json	Patch
@atlaspack/reporter-lsp	Patch
@atlaspack/reporter-sourcemap-visualiser	Patch
@atlaspack/reporter-tracer	Patch
@atlaspack/resolver-glob	Patch
@atlaspack/runtime-browser-hmr	Patch
@atlaspack/runtime-js	Patch
@atlaspack/runtime-react-refresh	Patch
@atlaspack/runtime-service-worker	Patch
@atlaspack/runtime-webextension	Patch
@atlaspack/transformer-babel	Patch
@atlaspack/transformer-css	Patch
@atlaspack/transformer-posthtml	Patch
@atlaspack/transformer-react-refresh-wrap	Patch
@atlaspack/transformer-typescript-types	Patch
@atlaspack/transformer-webextension	Patch
@atlaspack/transformer-webmanifest	Patch
@atlaspack/validator-eslint	Patch
@atlaspack/validator-typescript	Patch
@atlaspack/resolver-default	Patch
@atlaspack/resolver-tesseract	Patch
@atlaspack/types	Patch
@atlaspack/packager-ts	Patch
@atlaspack/transformer-jsonld	Patch

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[github-actions]

📊 Type Coverage Report

Coverage Comparison

Metric	Baseline	Current	Change
Coverage Percentage	92.03%	92.03%	➡️ 0.00%
Correctly Typed	201,335	201,351	+16
Total Expressions	218,749	218,765	+16
Untyped Expressions	17,414	17,414	+0

Files with Most Type Issues (Top 15)

File	Issues	Affected Lines
packages/core/integration-tests/test/javascript.ts	983	648
packages/core/integration-tests/test/cache.ts	885	626
packages/core/integration-tests/test/scope-hoisting.ts	623	490
packages/utils/node-resolver-core/test/resolver.ts	476	177
packages/core/integration-tests/test/html.ts	468	294
packages/core/integration-tests/test/sourcemaps.ts	356	176
packages/core/test-utils/src/utils.ts	330	205
packages/core/integration-tests/test/incremental-bundling.ts	298	206
packages/core/core/src/dumpGraphToGraphViz.ts	251	108
packages/core/integration-tests/test/output-formats.ts	227	161
packages/transformers/webextension/src/WebExtensionTransformer.ts	210	80
packages/core/integration-tests/test/react-refresh.ts	197	71
packages/core/integration-tests/test/css-modules.ts	191	107
packages/core/core/src/requests/TargetRequest.ts	190	133
packages/core/integration-tests/test/babel.ts	187	115

---

This report was generated by the Type Coverage GitHub Action

[github-actions]

📊 Benchmark Results

✅ No significant performance changes detected.

📊 Benchmark Results

Overall Performance

Test	Duration	JS Memory Peak	Native Memory Peak	vs Baseline	Status
Three.js Real Repository (JS)	16.74s	2.00GB	2.07GB	N/A	⚪ New
Three.js Real Repository (Native)	24.88s	3.07GB	3.34GB	N/A	⚪ New

🔍 Detailed Phase Analysis

Three.js Real Repository (JS)

Phase	Duration (avg)	Duration (p95)	Memory Peak (avg)	Memory Peak (p95)
resolving	9.06s	9.15s	1.35GB	1.50GB
transforming	9.05s	9.14s	1.35GB	1.50GB
bundling	8.84s	8.94s	1.35GB	1.50GB
bundled	8.42s	8.51s	1.45GB	1.59GB
packaging	6.25s	6.32s	1.59GB	1.68GB
optimizing	6.08s	6.14s	2.00GB	2.05GB

Three.js Real Repository (Native)

Phase	Duration (avg)	Duration (p95)	Memory Peak (avg)	Memory Peak (p95)
bundling	15.03s	19.67s	2.29GB	2.50GB
bundled	14.59s	19.22s	2.46GB	2.70GB
packaging	7.92s	8.57s	2.67GB	3.00GB
optimizing	7.74s	8.39s	3.07GB	3.34GB

💾 Unified Memory Analysis

Three.js Real Repository (JS) Memory Statistics

Memory Type	Metric	Min	Mean	Median	P95	P99	Max	Std Dev
JavaScript	RSS	1.54GB	1.79GB	1.96GB	2.05GB	2.05GB	2.05GB	221.72MB
	Heap Used	80.00MB	83.88MB	80.91MB	91.48MB	91.48MB	91.48MB	4.73MB
	Heap Total	94.35MB	122.64MB	126.87MB	171.85MB	171.85MB	171.85MB	26.84MB
	External	38.95MB	94.86MB	106.02MB	173.09MB	173.09MB	173.09MB	60.18MB
Native (Rust)	Physical Memory	1.44GB	1.63GB	1.64GB	1.87GB	2.00GB	2.07GB	135.09MB
	Virtual Memory	30.19GB	30.89GB	30.89GB	31.14GB	31.32GB	31.40GB	198.37MB

Sample Counts: JS: 6, Native: 267

Three.js Real Repository (Native) Memory Statistics

Memory Type	Metric	Min	Mean	Median	P95	P99	Max	Std Dev
JavaScript	RSS	2.30GB	2.81GB	2.82GB	3.34GB	3.34GB	3.34GB	345.33MB
	Heap Used	76.90MB	78.73MB	77.31MB	86.42MB	86.42MB	86.42MB	3.45MB
	Heap Total	88.70MB	102.02MB	99.20MB	137.64MB	137.64MB	137.64MB	16.57MB
	External	45.91MB	159.21MB	179.56MB	185.35MB	185.35MB	185.35MB	50.73MB
Native (Rust)	Physical Memory	2.35GB	2.73GB	2.73GB	3.16GB	3.30GB	3.34GB	247.94MB
	Virtual Memory	30.67GB	33.35GB	33.40GB	33.84GB	33.96GB	34.04GB	492.67MB

Sample Counts: JS: 6, Native: 578

🖥️ Environment

• Node.js: v22.17.0
• Platform: linux (x64)
• CPU: AMD EPYC 7763 64-Core Processor
• Total Memory: 15.62GB
• Git SHA: 6724864
• Branch: oscar/js-transformer/native-dead-code-elim
• Timestamp: 2025-11-20T00:08:18.724Z