vite-sass-bug

Bug repro: Vite 8 + pnpm + Windows — SCSS @use fails when the package exports field maps a wildcard path via the sass condition to an underscore-prefixed partial.

The Bug

When using @use to import an SCSS partial from a package that exposes it via the sass exports condition:

@use '@vite-sass-bug/example/styles/mixins';

The package's exports field is:

"./styles/*.scss": "./dist/styles/*.scss",
"./styles/*": {
  "sass": "./dist/styles/*.scss"   // maps  styles/mixins  →  dist/styles/_mixins.scss
}

• Linux / macOS – Vite constructs the sub-path as ./styles/_mixins (forward slash), which correctly matches the ./styles/* pattern. Build succeeds. ✔
• Windows – Vite constructs the sub-path as ./styles\_mixins (backslash), which does not match ./styles/*. Build fails. ✘

Error on Windows

[vite] Pre-transform error: [sass] Error:
  "./styles\_mixins" is not exported under the conditions
  ["sass", "style", "development", "import"]
  from package @vite-sass-bug/example
  (see exports field in …\node_modules\@vite-sass-bug\example\package.json)

Repo Structure

packages/
  example/          ← Package with underscore-prefixed _mixins.scss + exports `sass` condition
  vite-app/         ← Vite 8 starter that does @use 'example/styles/mixins'

Reproduce Locally

pnpm install
pnpm --filter vite-app run build   # succeeds on Linux/macOS, fails on Windows

CI Results

The GitHub Actions workflow runs vite build on all three platforms:

Platform	Expected result
ubuntu-latest	✅ passes
macos-latest	✅ passes
windows-latest	❌ fails (bug)