fix: warn when publicDir and outDir are nested

[patak-dev]

Description

There have been a few reports of people having issues debugging after setting an outDir and publicDir that are nested. I think Vite should disable the public dir feature and warn the user in this case.

Example:

export default {
  build: {
    outDir: 'public/assets/dist',
  },
};

See discussion at Discord from @fvsch and a previous issue #3173

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[12dgyyytewz2235]

Hi

[ArnaudBarre]

Is there any case where it's useful to have this?
It could create a difference between dev & preview

[patak-dev]

If cleanOutDir is false, the size of dist would spiral out of control. If we want to avoid the diff, we could emit the warning and copy things anyways.

[ArnaudBarre]

My point is that probably this is a misconfiguration of user that don't understand how the public folder works and we should throw instead if there is no good usecase for this.
And if they are very specific, user could still disable copyPublicDir and do copy("dist", "public/dist") on a post build step

[bluwy]

I think I'm ok with a warning as a start. I could see some setups wanting the outDir to be in publicDir intentionally, and is fine to suppress the warning.

[patak-dev]

I think I'm ok with a warning as a start. I could see some setups wanting the outDir to be in publicDir intentionally, and is fine to suppress the warning.

Currently the PR will bail out of copying the publicDir content to outDir, and not only do a warning. Do you think we should only issue the warning? Probably not a bad idea for a patch.

Do you have any example of when outDir should be in publicDir? It seems to me that we should have thrown from the start in this case and it isn't something we should support. If we keep copying and only do a warning now, I would still lean to start throwing in Vite 5

[bluwy]

Ah ok I didn't realize we support publicDir: false, which I thought if they want to achieve that they can suppress the warning instead. In that case I think we can follow your idea to only warn + keep copying, then in Vite 5 we can error out instead (or skip copying).

Do you have any example of when outDir should be in publicDir?

In the past when Svelte's main tooling is Rollup, the convention is to build into the public directory, that way you deploy your project through the public directory instead. It's probably rare to have this setup with Vite now but I remember seeing some setups like this before on Discord/Discussions.

[ArnaudBarre]

I don't see how copy public inside public dir is a wanted setup. I don't think going for throw now will be an issue, but because I think the this very unlikely given the disk issue with multiple build, it's fine for me now or in Vite 5

[patak-dev]

Ok, let's start emitting the warning so we can start throwing in Vite 5. I did that here:

• cf54822 (#13742)