CSS preprocessor support with `transformer: 'lightningcss'` #19112

taras-turchenko-moc · 2024-12-31T13:45:49Z

Describe the bug

Lightningcss fails on scss single line comments when using it as a transformer. It's strange because it should be processed by scss to generate valid css comments since it supports only multiline comments. I has another part of an app bundling by rspack and it works fine so it appears a vite bug

Reproduction

https://github.com/taras-turchenko-moc/lightningcss-scss-comments-bug

Steps to reproduce

Reproduction link has a github repo with default vanilla setup, enabled lightningcss, renamed style.css to scss and added a comment

npm install
npm run build

System Info

System:
    OS: macOS 15.1.1
    CPU: (14) arm64 Apple M3 Max
    Memory: 436.25 MB / 36.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.11.0 - ~/.nvm/versions/node/v22.11.0/bin/node
    Yarn: 1.22.22 - ~/.nvm/versions/node/v22.11.0/bin/yarn
    npm: 10.9.0 - ~/.nvm/versions/node/v22.11.0/bin/npm
    bun: 1.1.42 - /opt/homebrew/bin/bun
  Browsers:
    Chrome: 131.0.6778.205
    Safari: 18.1.1
  npmPackages:
    vite: ^6.0.5 => 6.0.6

Used Package Manager

npm

Logs

Click to expand!

> [email protected] build
> vite build --debug

  vite:config bundled config file loaded in 16.55ms +0ms
  vite:config using resolved config: {
  vite:config   css: {
  vite:config     transformer: 'lightningcss',
  vite:config     preprocessorMaxWorkers: 0,
  vite:config     devSourcemap: false,
  vite:config     lightningcss: {
  vite:config       targets: {
  vite:config         chrome: 5242880,
  vite:config         edge: 5242880,
  vite:config         safari: 917504,
  vite:config         firefox: 5111808,
  vite:config         opera: 4390912
  vite:config       }
  vite:config     }
  vite:config   },
  vite:config   build: {
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  vite:config     outDir: 'dist',
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  vite:config } +12ms
vite v6.0.6 building for production...
✓ 6 modules transformed.
x Build failed in 22ms
error during build:
[vite:css] [lightningcss] Invalid empty selector
file: /Users/master/Projects/lightningcss-scss-comments-bug/src/style.scss:17:0
SyntaxError: [lightningcss] Invalid empty selector

Validations

Follow our Code of Conduct
Read the Contributing Guidelines.
Read the docs.
Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
The provided reproduction is a minimal reproducible example of the bug.

The text was updated successfully, but these errors were encountered:

btea · 2025-01-02T09:31:28Z

Problems with the lightningcss side. parcel-bundler/lightningcss#624

taras-turchenko-moc · 2025-01-02T14:53:18Z

@btea But why lightningcss even trying to process scss files? Shouldn't it be transformed by sass before passing to lightningcss?

taras-turchenko-moc · 2025-01-02T14:54:26Z

As I said before I have another part of an app that also using lightningcss and it doesnt have any issues with it because rspack/webpack transforms scss file to css before passing it to lightningcss loader

btea · 2025-01-04T00:12:53Z

@btea But why lightningcss even trying to process scss files? Shouldn't it be transformed by sass before passing to lightningcss?

Because you use lightningcss as transformer.
https://github.com/taras-turchenko-moc/lightningcss-scss-comments-bug/blob/6000ec4ced6e0452cd85d06e52c38335777d6d66/vite.config.js#L4-L6

taras-turchenko-moc · 2025-01-06T08:05:19Z

But scss is not a valid css file and lightningcss shouldn't transform raw scss files the same way lightningcss shouldn't transform sass or less

sapphi-red · 2025-01-07T05:04:24Z

CSS preprocessors are not supported with transformer: 'lightningcss' yet.
https://vite.dev/guide/features.html#lightning-css:~:text=cssMinify%3A%20%27lightningcss%27.-,NOTE,CSS%20Pre%2Dprocessors%20aren%27t%20supported%20when%20using%20Lightning%20CSS.,-Static%20Assets

I have a PR here: #19071

taras-turchenko-moc added the pending triage label Dec 31, 2024

btea added the bug: upstream Bug in a dependency of Vite label Jan 2, 2025

sapphi-red removed the bug: upstream Bug in a dependency of Vite label Jan 7, 2025

sapphi-red added feat: css p2-nice-to-have Not breaking anything but nice to have (priority) and removed pending triage labels Jan 7, 2025

sapphi-red changed the title ~~lightningcss fails in scss files on single line comments~~ CSS preprocessor support with transformer: 'lightningcss' Jan 7, 2025

sapphi-red linked a pull request Jan 7, 2025 that will close this issue

feat(css): support preprocessor with lightningcss #19071

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CSS preprocessor support with `transformer: 'lightningcss'` #19112

CSS preprocessor support with `transformer: 'lightningcss'` #19112

taras-turchenko-moc commented Dec 31, 2024 •

edited

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btea commented Jan 2, 2025

taras-turchenko-moc commented Jan 2, 2025

taras-turchenko-moc commented Jan 2, 2025

btea commented Jan 4, 2025

taras-turchenko-moc commented Jan 6, 2025

sapphi-red commented Jan 7, 2025

CSS preprocessor support with transformer: 'lightningcss' #19112

CSS preprocessor support with transformer: 'lightningcss' #19112

Comments

taras-turchenko-moc commented Dec 31, 2024 • edited Loading

Describe the bug

Reproduction

Steps to reproduce

System Info

Used Package Manager

Logs

Validations

btea commented Jan 2, 2025

taras-turchenko-moc commented Jan 2, 2025

taras-turchenko-moc commented Jan 2, 2025

btea commented Jan 4, 2025

taras-turchenko-moc commented Jan 6, 2025

sapphi-red commented Jan 7, 2025

CSS preprocessor support with `transformer: 'lightningcss'` #19112

CSS preprocessor support with `transformer: 'lightningcss'` #19112

taras-turchenko-moc commented Dec 31, 2024 •

edited

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