fix: Unvirtualize importer paths in webpack and rspack

[edemaine]

I found that unplugin in webpack mode (and rspack mode) virtualized my resolved filenames (because I added a custom extension and the file didn't exist), but didn't unvirtualize the filenames when giving them back to me via the importer second argument to resolveId.

This simple PR fixes this issue by decoding virtualized filenames in importer, so that webpack and rspack behave like other systems. Includes a test with a simple mangling of filename (adding an extra .js to end of .js files).

[pkg-pr-new]

Open in Stackblitz

pnpm add https://pkg.pr.new/unjs/unplugin@430

commit: ea94e55

[antfu]

From the high-level this makes sense to me. I guess ideally this should be a non-breaking fix?

/cc @ahabhgk can you also help to check the rspack part to see if it's expected? Thanks

[edemaine]

I guess ideally this should be a non-breaking fix?

I think so... I can't imagine anyone doing something useful with the virtual importer filename. At least, the main use I know of for importer is to resolve relative ids relative to the importer, and without this change, you can't really do that (without painful workarounds). Given that the virtualization is done entirely within unplugin, I think this PR changes the behavior to be in line with expectation.

[ahabhgk]

Thanks, the rspack part looks good to me