Align behavior of SWC transform & transformSync

[Brooooooklyn]

fixes #35661

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running yarn lint

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
buildDuration	15.3s	15.2s	-76ms
buildDurationCached	6.2s	6.1s	-65ms
nodeModulesSize	463 MB	463 MB	✓

Page Load Tests Overall increase ✓

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.07	3.056	-0.01
/ avg req/sec	814.2	818.14	+3.94
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.193	1.173	-0.02
/error-in-render avg req/sec	2095.23	2131.75	+36.52

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
925.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	28.6 kB	28.6 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.3 kB	72.3 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
_app-HASH.js gzip	1.36 kB	1.36 kB	✓
_error-HASH.js gzip	193 B	193 B	✓
amp-HASH.js gzip	308 B	308 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	3.08 kB	3.08 kB	✓
head-HASH.js gzip	359 B	359 B	✓
hooks-HASH.js gzip	920 B	920 B	✓
image-HASH.js gzip	5.71 kB	5.71 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.63 kB	2.63 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	391 B	391 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16.3 kB	16.3 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
index.html gzip	531 B	531 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
buildDuration	17.4s	17.3s	-98ms
buildDurationCached	6.1s	6.1s	-68ms
nodeModulesSize	463 MB	463 MB	✓

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.072	3.059	-0.01
/ avg req/sec	813.93	817.25	+3.32
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.176	1.183	⚠️ +0.01
/error-in-render avg req/sec	2125.89	2113.7	⚠️ -12.19

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
925.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	29.1 kB	29.1 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.9 kB	72.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	179 B	179 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	324 B	324 B	✓
dynamic-HASH.js gzip	3.08 kB	3.08 kB	✓
head-HASH.js gzip	357 B	357 B	✓
hooks-HASH.js gzip	921 B	921 B	✓
image-HASH.js gzip	5.76 kB	5.76 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	2.74 kB	2.74 kB	✓
routerDirect..HASH.js gzip	322 B	322 B	✓
script-HASH.js gzip	392 B	392 B	✓
withRouter-HASH.js gzip	317 B	317 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16.4 kB	16.4 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
_buildManifest.js gzip	457 B	457 B	✓
Overall change	457 B	457 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js align-transform-sync	Change
index.html gzip	527 B	527 B	✓
link.html gzip	541 B	541 B	✓
withRouter.html gzip	525 B	525 B	✓
Overall change	1.59 kB	1.59 kB	✓

Commit: df730bd

[kdy1]

Cool, I love this approach!

I'm also glad that napi-rs is getting better.