`pathFilter` (or some new API) should support implementations of `exports`

In lieu of this module supporting exports out of the box, it would be awesome if consumers could use its existing capabilities (packageFilter, pathFilter etc.) to implement support for exports on the consumer side.

I have experimented a bit with this, and from what I can tell there are 2 issues:

1. resolve adds index if a directory is specified (https://github.com/browserify/resolve/blob/f1b51848ecb7f56f77bfb823511d032489a13eab/lib/sync.js#L192). This can potentially cause issues in the case index is not specified by the user as changing it to . (which is what a directory means in exports) is not necessarily a safe operation. Not sure how to mitigate this in a way that’s backwards compatible.
2. I tried to use pathFilter which works great for require('some-module/thing'), but it doesn’t work for require('./some-thing') from within a module. Relative imports within a module isn’t restricted by exports, but pathFilter cannot know if the resolution request is for a relative file or not. A solution here is maybe to include a flag saying if it’s relative within the package or not?

[SimenB]

Right, it breaks a test, but I think that test is faulty (it imports a “local” module with a package.json with exports via a relative path, but that is not in node_modules). I think that’s just wrong behavior, so it failing now is actually a bug fix and my old test was just bad 😅

Might just roll this out behind a config flag and hope people test it and report instances where it behaves wrong (after adding more tests)

[SimenB]

Ok, closing again 🙈 My solution is to pop of anything trailing after pkg/ or @scope/pkg/, add ./package.json and resolve that using resolve, and if package.json has exports resolve those with anything trailing (or . if nothing), and return the full path. No packageFilter or pathFilter at all. In theory a tiny bit faster as well as we head straight for the package.json file and potentially shortcut instead of traversing and checking for file existence.

(code is in above PR if this explanation made no sense, which it probably doesn’t)