Shared external module causes compiler to lockup

[david-driscoll]

I have a very strange issue that I've finally figured out the cause of, as it's really very strange.

It appears that if there is a dependency, that exists in two locations, and it defines typings as external, then tsc gets confused and cannot reason about them both.

Setup

• Using atom-typescript as my editor, though the issue shows up when trying to compile with tsc as well.
• I'm on a windows machine.

My folder structure looks like:

• c:\Dev\Omnisharp\omnisharp-atom
  • \node_modules\omnisharp-client symlink to c:\Dev\Omnisharp\omnisharp-node-client
  • \node_modules\@reactive\rxjs symlink to c:\Dev\reactivex\RxJS
• c:\Dev\Omnisharp\omnisharp-node-client
  • \node_modules\@reactive\rxjs symlink to c:\Dev\reactivex\RxJS
• c:\Dev\reactivex\RxJS

Everything is typically working great, I'm working on typings for RxJS 5.0, and updating omnisharp-client without issue.

When I got to omnisharp-atom an issue revealed itself, if I define Observable<T> as a return type for a method, with the above setup, then tsc get's confused and fails to compile. It gets into some sort of infinite loop.

Working

If I update things so that they look like:

• c:\Dev\Omnisharp\omnisharp-atom
  • \node_modules\omnisharp-client (no symlink)
    • \node_modules\@reactive\rxjs (removed)
  • \node_modules\@reactive\rxjs symlink to c:\Dev\reactivex\RxJS

Then everything is happy and works as expected.

Without symlinks

If I update things so that they look like:

• c:\Dev\Omnisharp\omnisharp-atom
  • \node_modules\omnisharp-client (no symlink)
    • \node_modules\@reactive\rxjs (symlink or non-symlink)
  • \node_modules\@reactive\rxjs symlink to c:\Dev\reactivex\RxJS

Then tsc fails to operate and will sit and consume CPU forever until it is killed.

[mhegazy]

@vladima can you take a look

[vladima]

@david-driscoll I've tried to repro it but with no luck however this sounds like a serious issue. Can you please share a self contained repro so we can address it properly?

[david-driscoll]

Sure, I can recreate it on demand with my current solution, so I'll try zipping it up and double checking it still fails, then post a link.

[vladima]

thanks!

[david-driscoll]

So creating a zip failed to extract if you're on windows (like myself) because of long paths.

I've created a batch file that will setup the scenario, of course feel free to review it for an malicious code. It's just pulling down a few git repos, running npm install for those repos and setting up the same symlinks.

https://onedrive.live.com/redir?resid=B65E6B05AE4EE402!237452&authkey=!AG6bNj8i96iBJJQ&ithint=file%2czip

[vladima]

I can see what is going on. Good news is that is not not related to module resolution - all files are resolved without any issues. The issue is that from compiler perspective it sees two different set of typings for RxJS: one in omnisharp-atom folder and another in omnisharp-node-client and all the time pretty much spent trying to relate types from these typing sets

[david-driscoll]

@vladima any traction on this issue, still seems to be a problem. Any proposed work arounds perhaps?

[vladima]

@david-driscoll TypeScript compiler currently does not follow symlinks so in your scenario it views RxJS in omnisharp-node-client\node_modules and omnisharp-atom\node_modules as different set of files and this leads to the worst possible option during type relationship check - comparing two identical structures. We have an issue to handle symlinks properly (#6365), once it is done - thinks should look better. As a workaround in your case can you push RxJS dependency higher in the directory hierarchy so compiler will use the same package for both omnisharp-node-client and omnisharp-atom?

├───node_modules
│   └───rx (symlink from rx-js)
├───omnisharp-atom
├───omnisharp-node-client
└───rx-js

[kruncher]

I am having the exact same issue with rxjs and use of symlinks.

It doesn't like it when I symlink the core package into my plugin package because rxjs occurs in both paths standard-generator/node_modules/core-package/node_modules/rxjs and standard-generator/node_modules/rxjs.

To me it seems that TypeScript could just look in standard-generator/node_modules for rxjs first, before attempting to look inside the deeper node_modules folders.

[vladima]

#8486 have added ability to follow symlinks during module resolution . Script this change should already be available in nightly builds, managed part and version of tsc.exe that support symlinks will be included in the next release