Function compileCSSPreprocessors

packages/vite/src/node/plugins/css.ts:1359–1414

(
  environment: PartialEnvironment,
  id: string,
  lang: PreprocessLang,
  code: string,
  workerController: PreprocessorWorkerController,
)

}

async function compileCSSPreprocessors(
  environment: PartialEnvironment,
  id: string,
  lang: PreprocessLang,
  code: string,
  workerController: PreprocessorWorkerController,
): Promise<{
  code: string
  map?: ExistingRawSourceMap | { mappings: '' }
  deps?: Set<string>
}> {
  const { config } = environment
  const { preprocessorOptions, devSourcemap } = config.css
  const atImportResolvers = getAtImportResolvers(
    environment.getTopLevelConfig(),
  )
  const opts = {
    ...((preprocessorOptions && preprocessorOptions[lang]) || {}),
    // important: set this for relative import resolving
    filename: cleanUrl(id),
    enableSourcemap: devSourcemap ?? false,
  }

  const preProcessor = workerController[lang]
  const preprocessResult = await preProcessor(
    environment,
    code,
    config.root,
    opts,
    atImportResolvers,
  )
  if (preprocessResult.error) {
    throw preprocessResult.error
  }

  let deps: Set<string> | undefined
  if (preprocessResult.deps.length > 0) {
    const normalizedFilename = normalizePath(opts.filename)
    // sometimes sass registers the file itself as a dep
    deps = new Set(
      [...preprocessResult.deps].filter(
        (dep) => normalizePath(dep) !== normalizedFilename,
      ),
    )
  }

  return {
    code: preprocessResult.code,
    map: combineSourcemapsIfExists(
      opts.filename,
      preprocessResult.map,
      preprocessResult.additionalMap,
    ),
    deps,
  }
}

const configToAtImportResolvers = new WeakMap<