fix: style pollution on custom theme

[antfu]

When using a custom theme, the style from the default theme will be injected and polluting the custom theme (overrides) due to the styles import side effect from re-exporting the defaultTheme here:

vitepress/src/client/app/exports.ts

Line 29 in 18d18d2

export { default as defaultTheme } from '/@default-theme/index'

Repro: https://codesandbox.io/s/vitepress-style-pollution-p5kvq?file=/index.md

This PR removed the redirecting as it does not seem to be used and users should always import the theme from vitepress/dist/client/theme-default explicitly.

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[antfu]

@knightly-bot build this

[knightly-bot]

🌒 Knightly build enabled, release every night at 00:00 UTC ^{(skip if no change)}

📦 npm package

[patak-dev]

I think this export was added after this discussion: #157 (comment)
The idea was that users that only need to extend the theme to register a few global components, wouldn't need to also take care of importing the styles and knowing the deep path to reach the theme:

// .vitepress/theme/index.js
import { defaultTheme } from 'vitepress'
import MyGlobalComp from './Comp.vue'

defaultTheme.enhanceApp = ({ app }) => {
  app.component('MyGlobalComp', MyGlobalComp)
}

But I see your point that it is impossible to use the theme without any styles. Maybe there is a way to opt out with an option in the theme.enhanceApp() function?

[antfu]

@matias-capeletto The current implementation make importing vitepress non-side-effect-free.

import 'vitepress' // will import the css side effects as well

I don't think they can be solved without some hacks. I am thinking user should import the default theme explicitly like:

import defaultTheme from 'vitepress/dist/client/default-theme`

Which is also recommended by the Customization Guide

---

Maybe we can add exports alias in package.json to achieve something like

import defaultTheme from 'vitepress/default-theme`

And I think the enhanceApp hook is a good idea, and we can use it regardless the default or custom theme

import { enhanceApp } from 'vitepress'

enhanceApp(({ app }) =>  {

})

[patak-dev]

Which is also recommended by the Customization Guide

Yes, the change was not documented and I think it was still WIP. Totally agree that importing vitepress should not include the CSS.
I like your proposal 👍🏼

import defaultTheme from 'vitepress/default-theme`