build.emptyOutDir no longer empties out the entire directory since v3.2.x

[benjaminprojas]

Describe the bug

In the past, using build.emptyOutDir would empty out the entire directory defined by build.outDir even when the build.rollupOptions.output.dir was set to a different directory. Since v3.2.0 this has changed to only empty out what is defined in build.rollupOptions.output.dir

Reproduction

https://stackblitz.com/edit/vitejs-vite-lmgy3k?file=vite.config.js,package.json

Steps to reproduce

There is a file inside dist called: file-to-be-removed.html. This file should be deleted when a new build is made (dist directory is emptied).

run npm run build to see that the files inside the dist directory are not deleted, only the files inside the dist/assets directory are deleted.

Alternatively, use the following for 3.1.8 to see it working as expected: https://stackblitz.com/edit/vitejs-vite-lmgy3k?file=vite.config.js,package.json

System Info

System:
    OS: macOS 12.6
    CPU: (10) arm64 Apple M1 Max
    Memory: 137.77 MB / 32.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 16.15.0 - /usr/local/bin/node
    npm: 8.9.0 - /opt/homebrew/bin/npm
  Browsers:
    Chrome: 106.0.5249.119
    Firefox: 104.0
    Safari: 16.0
  npmPackages:
    @vitejs/plugin-react: ^1.3.2 => 1.3.2 
    vite: 3.2.1 => 3.2.1

Used Package Manager

npm

Logs

No response

Validations

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[sapphi-red]

The previous behavior was considered as a bug and changed by #9748. I'm not sure which one is more natural.

[patak-dev]

What we defined in #9748 for nested output dirs is that the contents of all output folders would be deleted (but not the nested folder structure). cc @qmhc

The repro doesn't have multiple output dirs, only one that overwrites the value of build.outDir. This is a strange setup, I don't know if we should count this as a regression. Shouldn't assetFileNames be used here?
But if users are configuring Vite in this way, maybe it isn't a bad idea to always include build.outDir as target to remove its content (that should fix this issue)

[qmhc]

In my thought, we can allow the build.outDir is optional with descripting that any build.rollupOptions.output.dir will overwrite it, and we can warn when users using both them.

[benjaminprojas]

@patak-dev the repro was minimal to show how to reproduce, but we do use assetFileNames as well. We have a pretty complex setup where we put things in different folders inside the dist directory. However I want the entire outDir to be emptied during each build.

Also, stands to reason (imho) that if you have:

outDir      : 'dist',
emptyOutDir : true

Then the dist directory should be emptied.

[arnaudbroes]

I completely agree with @benjaminprojas here. I think that the root dist directory should be the one that is emptied out.