fix: add `realpath` to host to properly resolve monorepos / symlinks

[agilgur5]

Summary

Implement realpath in host.ts to properly resolve symlinks, i.e. for monorepos

While the code for this is tiny, this is a pretty huge bugfix given the number of users that have run into this here and downstream (in microbundle, TSDX, etc) -- glad to finally fix such a common error!

Details

• tested this in a pnpm repo with symlinked deps and it worked there, so I believe this fixes all pnpm issues

  • it may also fix some Lerna issues if they were due to symlinks, but I didn't check those
  • EDIT: yes, this fixed some Lerna issues too. Including Lerna + NPM
  • not sure about others, e.g. Rush, Yarn workspaces, Yarn PnP
  • EDIT: this fixed some Rush repos that used pnpm as well, but Rush is compatible with multiple package managers, so unsure of others.
  • EDIT: given the confirmed fixes in the edits above, this has likely fixed all symlink issues with all package managers

• I figured out this was needed by staring at the TS source code and then I found this line

  • it expects host.realpath to be implemented for TS's realPath to work correctly, otherwise it just returns the path with no transformation (i.e. the path to the symlink instead of the realpath)
  • this is not documented anywhere and we were hitting this when calling getEmitOutput, before even using moduleNameResolver
  • so I just tried implementing it... and it worked!
  • notably, the other Rollup TS plugins don't implement this either???
  • not sure how they don't error on this??

See my root cause analysis in https://github.com/ezolenko/rollup-plugin-typescript2/issues/234#issuecomment-1139202740 for (much) more details

Review Notes

• note that I added a ! as realpath doesn't have to be implemented on ts.sys... but it is in the default implementation (see comment)
  • I originally had a ternary with fs.realpathSync if it didn't exist but that is literally what the default implementation uses
  • can add this back in the future if it becomes an issue

References

• Fixes #330
• Fixes #234
• ~Possible fix for #254, which mentions pnpm symlinks, but haven't tested~
  • EDIT: I investigated and responded in https://github.com/ezolenko/rollup-plugin-typescript2/issues/254#issuecomment-1140503934 -- that's actually completely unrelated and pnpm and other things were totally red herrings to the root cause
• Possible fix for #214 ~and #188~, which are Lerna repos, but haven't tested
  • EDIT: Fixes #214
  • EDIT: Investigated and responded in https://github.com/ezolenko/rollup-plugin-typescript2/issues/188#issuecomment-1162411279, and that was a different issue that is effectively duplicative of #216 / #295. Those were also monorepo issues, but they were fixed before this PR (incidentally, by upgrading @rollup/pluginutils, per the linked comments)
• Possible fix for #274, which mentions "monorepo" and has a similar kind of issue with declaration output as #330, but there is no repro to test against
• ~Also possible fix for #237, which has a workaround and mentions "monorepo", but unsure if related and no repro was provided there~
  • EDIT: I investigated a bit more there and responded in https://github.com/ezolenko/rollup-plugin-typescript2/issues/237#issuecomment-1139222519 -- that actually seems to be correct behavior and the "workaround" is the proper solution. Unsure about the second, unrelated feature request/PR that was added but it solved itself
• As a result, this at least partially fixes the common pattern of monorepo / symlink issues in this codebase that I mentioned in https://github.com/ezolenko/rollup-plugin-typescript2/pull/311#issuecomment-1115491161

Downstream fixes:

• Fixes https://github.com/developit/microbundle/issues/931, which is a Rush monorepo
• Fixes https://github.com/jaredpalmer/tsdx/issues/967 and fixes https://github.com/jaredpalmer/tsdx/issues/953, which both use Rush and PNPM
• There's probably more of these that I didn't find in a quick search

[agilgur5]

I fixed the tests I added for this on Windows (which I suspected might error there).

Just need #331 to be merged so that this can be rebased on top, then everything should pass. CI is currently failing on Windows due to https://github.com/ezolenko/rollup-plugin-typescript2/pull/329#issuecomment-1138876847 being merged early and master being currently broken as a result, not because of this PR.

[ezolenko]

This one needs a release I guess

[agilgur5]

This one needs a release I guess

yep, that it would.

think I'll get a few more PRs in today for bugfixes if you want to batch a few things together instead

[ezolenko]

Ok, let me know when you have everything you had in mind in.

[agilgur5]

@ezolenko #334 and #338 were the last two fixes I was looking to get in, so ready for a batched release now 👍

Note that you'll need to do a build && build-self beforehand as I didn't do that in my PRs (I normally leave dist/ for the release process to handle)

(Anything else that I'm working on is going to take longer to figure out the right approach, fix, and test, but think I've made great progress on bug squashing so far!)

[agilgur5]

Released in 0.32.0 🎉

Just so you know, I edited the release notes to add sections by order of importance. This is similar to how I organized releases in TSDX. Would like to automate this, but I've never quite gotten around to release automation in OSS and my changelog generator is outdated now.

Also as a heads up, GitHub's auto-generated release notes seem to only include PRs, meaning it missed all the direct commits that you made. For the most part, those don't necessarily need call-outs in the release notes and can be seen in the full changelog (alternatively, we could also expand the "Internal" section and put a spoiler/<details> tag around it), but some, like the dependency updates -- which occasionally cause breaking changes (like in the case of @rollup/pluginutils's createFilter https://github.com/ezolenko/rollup-plugin-typescript2/issues/216#issuecomment-1140024487) -- may be better to include in the release notes just in case.