Support for scoping variables in CSS modules

[devongovett]

This adds opt-in support for scoping variables and other dashed identifiers in CSS modules. It also registers variables as symbols, and automatically removes unused variables. See parcel-bundler/lightningcss#183 for details.

This is enabled in package.json via the new object config for cssModules, which also supports custom pattern config to specify how names are generated. Due to this, there is also a global option to enable CSS modules globally when using this object config.

{
  "@parcel/transformer-css": {
    "global": true,
    "pattern": "foo-[hash]-[local]",
    "dashedIdents": true
  }
}

[parcel-benchmark]

Benchmark Results

Kitchen Sink 🚨

Timings

Description	Time	Difference
Cold	FAILED	-0.00ms
Cached	FAILED	-0.00ms

Cold Bundles

No bundles found, this is probably a failed build...

Cached Bundles

No bundles found, this is probably a failed build...

React HackerNews ✅

Timings

Description	Time	Difference
Cold	9.62s	+14.00ms
Cached	480.00ms	+4.00ms

Cold Bundles

No bundle changes detected.

Cached Bundles

No bundle changes detected.

AtlasKit Editor ✅

Timings

Description	Time	Difference
Cold	1.71m	-1.10s
Cached	2.67s	-28.00ms

Cold Bundles

Bundle	Size	Difference	Time	Difference
dist/esm.c7dc1640.js	61.96kb	+0.00b	1.27m	+34.28s ⚠️
dist/workerHasher.e50d242f.js	1.72kb	+0.00b	1.27m	+34.29s ⚠️
dist/16.1969624f.js	1.08kb	+0.00b	41.37s	+3.29s ⚠️
dist/16.069344b7.js	905.00b	+0.00b	41.37s	+3.29s ⚠️
dist/simpleHasher.46d6f2e5.js	742.00b	+0.00b	1.27m	+34.29s ⚠️
dist/index.html	240.00b	+0.00b	1.27m	+42.94s ⚠️

Cached Bundles

Bundle	Size	Difference	Time	Difference
dist/esm.c7dc1640.js	61.96kb	+0.00b	42.13s	-34.69s 🚀
dist/workerHasher.e50d242f.js	1.72kb	+0.00b	42.13s	-34.69s 🚀
dist/16.1969624f.js	1.08kb	+0.00b	37.93s	-3.76s 🚀
dist/index.html	240.00b	+0.00b	36.68s	-40.19s 🚀

Three.js ✅

Timings

Description	Time	Difference
Cold	6.93s	-0.00ms
Cached	285.00ms	+13.00ms

Cold Bundles

No bundle changes detected.

Cached Bundles

No bundle changes detected.

Click here to view a detailed benchmark overview.