Project References Regression starting in Nightly 3.9.0-dev.20200313

[warrenfalk]

Project References do not appear be honored in tsserver starting in Nightly 3.9.0-dev.20200313. This results in an error in Visual Studio code when importing from 'some-pkg/dist/file' when that file has not yet been built.

TypeScript Version: 3.9.0-dev.20200313 and later

Search Terms:

references tsserver

Code

Minimal reproduction project attached. repro.zip

This seems to be an issue with tsserver, and so I can only reproduce it in Visual Studio Code (not with tsc -b).

The error is a regression starting in version 3.9.0-dev.20200313. There was no error in 3.9.0-dev.20200312 and previous.

To reproduce, use attached repro.zip, here are simple instructions and the screenshot of the result.

unzip repro.zip
cd repro-ts-bug
yarn install
code .
code src1/one.ts

See issue in 3.9.0-dev.20200313:

This should work because of a project reference to src2/tsconfig.json from src1/tsconfig.json, and it does work in the previous build of typescript.

---

You can see this is a regression. Installing the previous version and reloading the window demonstrates no error.

yarn add typescript@3.9.0-dev.20200312

And reload window. No issue in 3.9.0-dev-20200312

Expected behavior:

No error, as in second screenshot

Actual behavior:

Error:

Cannot find module '../dist2/two' or its corresponding type declarations.

Playground Link:
Unable to demonstrate project reference issues with playground (as far as I know)

Related Issues:

[warrenfalk]

@sheetalkamat, it appears this problem began with the merge of PR #37370, "Move useSourceOfProjectReferenceRedirect to program so other hosts can use it too, enabling it for WatchHost" with commit a76a166

Is this a regression, or am I misunderstanding something about how this should work?

[sheetalkamat]

Don't repro the issue at all:

[warrenfalk]

Hmm, indeed, I can only reproduce it on this machine. It didn't occur to me to try other machines - sorry about that...

But something has definitely changed in 20200313, though, because on this machine every version before that works, but every version after does not.

I will try to see if I can see why. Are there any hints you can give that might explain why this might work on one machine, but not on a nearly identical machine?

[sheetalkamat]

you could add --traceResolution and see whats going on in tsserver log..

[warrenfalk]

Ah, it was a vscode extension that I long forgot was there; I should have thought of that. It appears to be interfering in some way that breaks after 20200313. I don't need the extension so I am just removing it rather than look deeper. Thanks for the pointer, and sorry about wasting your time.

[RyanCavanaugh]

@warrenfalk glad we got it figured out; thanks for following up