building with --base "" results in /0 being used for the base instead

[JakeIsMeh]

Describe the bug

Overview

When doing vite build --base "", the resulting SPA loader has /0/ for all of it's hrefs and srcs.

Expected behaviour

the resulting SPA loader has a base path of / for all of it's hrefs and srcs.

Experienced Behaviour

the resulting SPA loader has a base path of /0/ for all of it's hrefs and srcs.

What I'm trying to do

I use actions/configure-pages@v3 which provides environment information for the workflow, such as the base path for the deployment.

It allows me to avoid specifying the base path in code as it is simply specified at deploy time in the build command like this:

# .github/workflow.yaml
- name: Build with Vite
  run: npx vite build --base "${{ steps.pages.outputs.base_path }}"

However, when deploying to a root base, configure-pages returns the base path as blank and not /, which is allowed as specified in the docs.

This results in a broken build as the SPA loader tries to load assets from domain.tld/0/assets/index-hash.js instead of domain.tld/assets/index-hash.js

Triaging I have done

Only affects vite@^4.3.0 as any older versions would error out when using --base ""
Only affects plain Vite projects, as I have successfully deployed a SvelteKit app using vite build --base "" (Vite 4.4.9)
(I tried with vite.new/vue, vite.new/svelte, vite.new/solid)

Reproduction

https://stackblitz.com/edit/vitejs-vite-gqpqgr?file=dist%2Findex.html

Steps to reproduce

Run npm i followed by npx vite build --base ""

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 16.20.0 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 9.4.2 - /usr/local/bin/npm
    pnpm: 8.6.10 - /usr/local/bin/pnpm
  npmPackages:
    @vitejs/plugin-vue: ^4.2.3 => 4.3.3 
    vite: ^4.4.9 => 4.4.9

Used Package Manager

npm

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.

[stackblitz]

Start a new pull request in StackBlitz Codeflow.

• vitejs-vite-gqpqgr (Open reproduction)

[btea]

A warning message has been printed.

[bluwy]

I guess we can handle this specific case to coerce 0 to "". The changes would be here:

vite/packages/vite/src/node/cli.ts

Line 116 in 1a2e5e6

.option('--base <path>', `[string] public base path (default: /)`)

With a similar change as:

vite/packages/vite/src/node/cli.ts

Line 128 in 1a2e5e6

.option('--host [host]', `[string] specify hostname`, { type: [convertHost] })