TS 5 Regression. tsconfig extends stop resolving references to node_modules

[Vidda777]

Bug Report

🔎 Search Terms

TS 5, tsconfig, extends, node modules

🕗 Version & Regression Information

5.0.2

In latest stable build, 4.9.5, tsconfig extends resolve correctly references to libraries on node modules. However, after trying out 5.0.2 it has stop working

• This changed between versions 4.9.5 and 5.0.2

⏯ Playground Link

No Playground, I quickly check and there is no support for tsconfig, package.json,...

💻 Code

No code, it's just configuration. Having a package.json declaring

 "devDependencies": {
    "@mylibrary/commons": "1.0.0",
    "typescript": "5.0.2"
  }

and a tsconfig with:
"extends": "@mylibrary/commons/configs/tsconfig.backend.json",

🙁 Actual behavior

The command tsc --build finish with error:

tsconfig.json:2:14 - error TS6053: File '@mylibrary/commons/configs/tsconfig.backend.json' not found.

2   "extends": "@mylibrary/commons/configs/tsconfig.backend.json",

🙂 Expected behavior

The command tsc --build finish correctly.

[ilogico]

This is most likely because @mylibrary/commons has an exports field on package,json without exporting the file.

[jakebailey]

I don't think we consider exports for tsconfig, just paths. But, I could be wrong.

I think what we need is the layout of whatever @mylibrary/commons is (plus maybe package.json). Bascially, a minimal repro, as this issue isn't enough.

[ilogico]

The reason I said is because I hit this problem when upgrading to 5.0 and I fixed it by adding an entry to the exports map.

[jakebailey]

Oh, very interesting!

[RyanCavanaugh]

I think this is a bug, AFAIK extends lookups should always be done as CJS lookups. Probably we'll have to revisit that logic at some point...

[ilogico]

Subpath exports are not specific to ESM.
In fact, I would say ignoring exports was the bug, even if fixing it is a breaking change.

[ilogico]

And considering this to be a bug and "fixing" it is also a breaking change.

[RyanCavanaugh]

"breaking change" does not include undoing accidental changes back to the prior behavior. That's an unusable definition.

[ilogico]

I don't want to discuss the semantics of breaking changes. Of course I accept that fixing bug might be a desirable breaking change, that was my initial point.
I think it's reasonable to assume that TS would use the same lookup algorithm as NodeJS and that everything else is a bug, a quirk, non-standard behaviour or whatever you want to call it. But if you think it's more important to keep the previous behaviour, I would say that's reasonable as well.

But maybe there's a middle ground where the lookup is done in the standard way (looking at the exports field) and then falling back to the directory structure as it did before.

[loucyx]

IDK if this is useful for the conversation and for debugging, but I had my exports field with this property set for a while now:

"exports": {
  // ...
  "./*.json": "./lib/*.json"
  // ...
}

And I still get the "File not found" error when trying to import it from other packages, which indeed is a regression from my point of view, but also indicates that the fix isn't "just using exports," because the "*" syntax is valid, and also having to specify file by file in the exports field is kinda unrealistic.

Hope I'm adding something useful to the conversation and this isn't just unwanted noise.

[mike-lischke]

I just upgraded to TS 5 and found the same issue with one of my own node packages ( repo, npm). With TS 5 I now get the error

Cannot find module 'antlr4-c3' or its corresponding type declarations.ts(2307)

Needless to say that I did not change any bit in the project where I'm using the node package. Just upgrading to TS 5 broke the import.

I played a bit with other node module resolution settings, but nothing helped. What sticks out when looking in the bundled node package is that there's no index.js file in the root folder. All the code is in the out/ folder.

Update: I solved the issue by setting the main entry in package.json to ./out, so it's not a critical problem (for me).

[jakebailey]

@mike-lischke This issue is about tsconfig's extends clause. Your issue is unrelated; please file a separate issue.