Fix absolute path handling for config validation in windows

[bluwy]

Changes

Fix passing absolute paths to root, srcDir, publicDir, outDir, cacheDir, build.client, and build.server on Windows. We currently have code like this:

astro/packages/astro/src/core/config/schema.ts

Line 251 in b3b9fc5

.transform((val) => new URL(appendForwardSlash(val), fileProtocolRoot)),

And they fail on Windows because val looks like C:\\User\\bob. The C: looks like a protocol when passed to new URL and that creates an invalid final URL. Switching to path.resolve fixes this for now.

Testing

Tested in #7682 where I passed the absolute root path in tests, and it failed. The fa32ff0 commit there fixes it, which I ported it to here to main first.

Besides that, no actual tests here yet, but CI should continue to pass.

Also thanks @hippotastic for testing that this works.

Docs

The docs for srcDir, publicDir, outDir, and cacheDir mentioned that they accept absolute paths. root, build.client, and build.server don't exactly mention it, but it would be nice if they work still for consistency.

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[Geoffrey-Pliez]

Hi,

Is it normal for the pathname of these paths to start with "/" on Windows?
Because it doesn't allow you to use the pathname in other projects like this one

[bluwy]

I don't think that's common on Windows. If you're dabbling with path file: URLs, you should use fileUrlToPath or pathToFileUrl to make sure they work across OS.

[Geoffrey-Pliez]

Ok, I'll try to explore the idea.
Thanks.