Multiline comment in :global declaration in Sass file that is a CSS module throws minification warning

[reintroducing]

Describe the bug

When working with CSS modules in Sass files and including multi-line comments inside of a :global declaration, the production build shows a warning.

Given the following code:

:global {
  /*
   * Add the correct display in all browsers.
   */
  summary {
    display: list-item;
  }
}

When running npm run build it outputs the following CSS:

{}summary{display:list-item}

This shows the following warning during the build:

vite v2.9.9 building for production...
✓ 31 modules transformed.
warnings when minifying css:
▲ [WARNING] Unexpected "{"

    <stdin>:1:1:
      1 │  {
        ╵  ^

Removing the multi-line comment results in a proper build output with no warnings.

Reproduction

https://github.com/reintroducing/vite-css-module-comment-bug

System Info

System:
    OS: macOS 12.3.1
    CPU: (10) arm64 Apple M1 Pro
    Memory: 82.06 MB / 16.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 16.13.0 - ~/.nvm/versions/node/v16.13.0/bin/node
    npm: 8.1.0 - ~/.nvm/versions/node/v16.13.0/bin/npm
  Browsers:
    Chrome: 102.0.5005.61
    Firefox: 97.0.1
    Safari: 15.4
  npmPackages:
    @vitejs/plugin-react: ^1.3.0 => 1.3.2
    vite: ^2.9.9 => 2.9.9

Used Package Manager

npm

Logs

> vite build --debug

  vite:config bundled config file loaded in 99.63ms +0ms
  vite:config using resolved config: {
  vite:config   plugins: [
  vite:config     'vite:build-metadata',
  vite:config     'alias',
  vite:config     'vite:react-babel',
  vite:config     'vite:react-refresh',
  vite:config     'vite:react-jsx',
  vite:config     'vite:modulepreload-polyfill',
  vite:config     'vite:resolve',
  vite:config     'vite:html-inline-proxy',
  vite:config     'vite:css',
  vite:config     'vite:esbuild',
  vite:config     'vite:json',
  vite:config     'vite:wasm',
  vite:config     'vite:worker',
  vite:config     'vite:asset',
  vite:config     'vite:define',
  vite:config     'vite:css-post',
  vite:config     'vite:build-html',
  vite:config     'vite:worker-import-meta-url',
  vite:config     'vite:watch-package-data',
  vite:config     'commonjs',
  vite:config     'vite:data-uri',
  vite:config     'rollup-plugin-dynamic-import-variables',
  vite:config     'vite:asset-import-meta-url',
  vite:config     'vite:build-import-analysis',
  vite:config     'vite:esbuild-transpile',
  vite:config     'vite:terser',
  vite:config     'vite:reporter',
  vite:config     'vite:load-fallback'
  vite:config   ],
  vite:config   build: {
  vite:config     target: [ 'es2019', 'edge88', 'firefox78', 'chrome87', 'safari13.1' ],
  vite:config     polyfillModulePreload: true,
  vite:config     outDir: 'dist',
  vite:config     assetsDir: 'assets',
  vite:config     assetsInlineLimit: 4096,
  vite:config     cssCodeSplit: true,
  vite:config     cssTarget: [ 'es2019', 'edge88', 'firefox78', 'chrome87', 'safari13.1' ],
  vite:config     sourcemap: false,
  vite:config     rollupOptions: {},
  vite:config     minify: 'esbuild',
  vite:config     terserOptions: {},
  vite:config     write: true,
  vite:config     emptyOutDir: null,
  vite:config     manifest: false,
  vite:config     lib: false,
  vite:config     ssr: false,
  vite:config     ssrManifest: false,
  vite:config     reportCompressedSize: true,
  vite:config     chunkSizeWarningLimit: 500,
  vite:config     watch: null,
  vite:config     commonjsOptions: { include: [Array], extensions: [Array] },
  vite:config     dynamicImportVarsOptions: { warnOnError: true, exclude: [Array] }
  vite:config   },
  vite:config   resolve: { dedupe: [ 'react', 'react-dom' ], alias: [ [Object], [Object] ] },
  vite:config   optimizeDeps: {
  vite:config     include: [ 'react/jsx-dev-runtime' ],
  vite:config     esbuildOptions: { keepNames: undefined, preserveSymlinks: undefined }
  vite:config   },
  vite:config   configFile: '/Users/mprzybylski/Desktop/vite-css-module-comment-bug/vite.config.js',
  vite:config   configFileDependencies: [
  vite:config     '/Users/mprzybylski/Desktop/vite-css-module-comment-bug/vite.config.js'
  vite:config   ],
  vite:config   inlineConfig: {
  vite:config     root: undefined,
  vite:config     base: undefined,
  vite:config     mode: undefined,
  vite:config     configFile: undefined,
  vite:config     logLevel: undefined,
  vite:config     clearScreen: undefined,
  vite:config     build: {}
  vite:config   },
  vite:config   root: '/Users/mprzybylski/Desktop/vite-css-module-comment-bug',
  vite:config   base: '/',
  vite:config   publicDir: '/Users/mprzybylski/Desktop/vite-css-module-comment-bug/public',
  vite:config   cacheDir: '/Users/mprzybylski/Desktop/vite-css-module-comment-bug/node_modules/.vite',
  vite:config   command: 'build',
  vite:config   mode: 'production',
  vite:config   isWorker: false,
  vite:config   isProduction: true,
  vite:config   server: {
  vite:config     preTransformRequests: true,
  vite:config     fs: { strict: true, allow: [Array], deny: [Array] }
  vite:config   },
  vite:config   preview: {
  vite:config     port: undefined,
  vite:config     strictPort: undefined,
  vite:config     host: undefined,
  vite:config     https: undefined,
  vite:config     open: undefined,
  vite:config     proxy: undefined,
  vite:config     cors: undefined,
  vite:config     headers: undefined
  vite:config   },
  vite:config   env: { BASE_URL: '/', MODE: 'production', DEV: false, PROD: true },
  vite:config   assetsInclude: [Function: assetsInclude],
  vite:config   logger: {
  vite:config     hasWarned: false,
  vite:config     info: [Function: info],
  vite:config     warn: [Function: warn],
  vite:config     warnOnce: [Function: warnOnce],
  vite:config     error: [Function: error],
  vite:config     clearScreen: [Function: clearScreen],
  vite:config     hasErrorLogged: [Function: hasErrorLogged]
  vite:config   },
  vite:config   packageCache: Map(0) { set: [Function (anonymous)] },
  vite:config   createResolver: [Function: createResolver],
  vite:config   worker: {
  vite:config     format: 'iife',
  vite:config     plugins: [
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object], [Object], [Object],
  vite:config       [Object]
  vite:config     ],
  vite:config     rollupOptions: {}
  vite:config   }
  vite:config } +3ms
vite v2.9.9 building for production...
✓ 31 modules transformed.
warnings when minifying css:
▲ [WARNING] Unexpected "{"

    <stdin>:1:1:
      1 │  {
        ╵  ^


dist/index.html                  0.44 KiB
dist/assets/index.fe5fb74e.css   0.31 KiB / gzip: 0.24 KiB
dist/assets/index.26a25dd7.js    139.63 KiB / gzip: 44.76 KiB

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 https://github.com/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.

[sapphi-red]

sass compiles

:global {
  /*
    * Add the correct display in all browsers.
    */
  summary {
    display: list-item;
  }
}

into

:global {
  /*
    * Add the correct display in all browsers.
    */
}
:global summary {
  display: list-item;
}

This is correct I think.

Then postcss + postcss-modules compiles it to

 {
  /*
    * Add the correct display in all browsers.
    */
}
summary {
  display: list-item;
}

This part does not seems to be working.

https://stackblitz.com/edit/node-2pmbyx?file=sass.js,postcss.js

[reintroducing]

@sapphi-red great find! does this need to be opened against PostCSS then? I'm happy to do so if that's the case.

[sapphi-red]

@reintroducing Yes. Would you report it to postcss-modules?

[reintroducing]

@sapphi-red I went ahead and opened madyankin/postcss-modules#136. Closing this as it is not a Vite issue. Thank you.