static assets in CSS url() without opening slash is not resolved or bundled

[xsjcTony]

Describe the bug

Static assets in CSS url() without opening slash / is not resolved or bundled with vite build.

For example, background-image: url('src/assets/sample.svg') will remain as is, without any file copied or path changed.

But background-image: url('/src/assets/sample.svg') will work correctly, with path changed to url('/assets/sample.svg') and file copied.

Both of the above are working correctly in dev mode.

I'm not sure if it's my problem or my responsibility to ensure the opening slash exists, but I can't find any related info in the doc or here. Sorry if I just missed something.

Reproduction

https://stackblitz.com/edit/vitejs-vite-2j2snf?file=src/App.css

System Info

System:
    OS: macOS 12.5
    CPU: (8) arm64 Apple M2
    Memory: 3.17 GB / 24.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 16.16.0 - ~/.nvm/versions/node/v16.16.0/bin/node
    Yarn: 1.22.19 - ~/.nvm/versions/node/v16.16.0/bin/yarn
    npm: 8.18.0 - ~/.nvm/versions/node/v16.16.0/bin/npm
  Browsers:
    Chrome: 104.0.5112.101
    Firefox: 103.0
    Safari: 15.6
  npmPackages:
    @vitejs/plugin-react: ^2.0.1 => 2.0.1 
    vite: ^3.0.9 => 3.0.9

Used Package Manager

pnpm

Logs

No response

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.

[sapphi-red]

Paths without the first / means relative path.
So in src/App.css, src/assets/sample.svg means src/src/assets/sample.svg and the behavior in build is correct.

I think we need a warning or make it consistent.