Monorepo workspace packages in devDependencies are not considered for auto-imports

[DerGernTod]

🔎 Search Terms

"import devDependencies"

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about devDependencies

⏯ Playground Link

https://github.com/DerGernTod/typescript-auto-import/tree/main

💻 Code

// file: packages/consumer-dependency/src/dep-consumer.ts
let m: MyInterface;

// file: packages/consumer-dependency/package.json
{
    ...
    "dependencies": {
        "lib": "workspace:*"
    }
}
// file: packages/consumer-dev-dependency/src/dev-consumer.ts
let m: MyInterface;

// file: packages/consumer-dependency/package.json
{
    ...
    "devDependencies": {
        "lib": "workspace:*"
    }
}

// file: packages/lib/src/the-lib.ts
export interface MyInterface {
    foo: string;
}

{
    ...
    "exports": {
        "./the-lib": "./dist/the-lib.js"
    }
}

🙁 Actual behavior

Fetching tsc suggestions on let m: MyInterface; in dep-consumer.ts yields the correct Add import from "lib/the-lib".

Fetching tsc suggestions on let m: MyInterface; in dev-consumer.ts yields no result.

🙂 Expected behavior

Fetching tsc suggestions on let m: MyInterface; in dev-consumer.ts also yields the correct Add import from "lib/the-lib".

Additional information about the issue

Please see the attached reproducer repo. I couldn't figure out a way to build this in TS playground. If there is a way, I'd be glad if someone could enlighten me :)

This might be related to pnpm workspaces imports. While building the reproducer, I started out with npm workspaces and file: dependencies. The behavior was a little different: for the dev dependencies, tsc tried to import from "../../lib/src/the-lib" (which obviously also doesn't work). The import from dependencies also worked fine though. After restarting the language server, once it also worked with "lib/the-lib" but I was never able to get a correct suggestion afterwards.

[RyanCavanaugh]

This is intentional. Dev dependencies aren't going to be there when your package is installed elsewhere, so importing them from package code is likely to be a mistake.

[DerGernTod]

Is there some documentation about this? I understand the rationale, but especially if you use moduleResolution: "bundler", that's not really a given and either way, it doesn't necessarily matter. The provided reproducer repo is somewhat of a simple replica of my large monorepo, where one of the packages is only types - for the reason to easily create a typedoc that is published and deployed to a webserver, and used in multiple monorepo packages.

Say I have package "lib" that only contains types and provides an interface PublicApi, then packages "api-node" and "api-browser", each of them creating an instance of their own PublicApi implementation. The interface is the same though, so that one is shared across both packages, but the implementation differs. Semantically, to me this means lib is a devDependency for both "api-node" and "api-browser" packages - the type only needs to exist during dev time (which is the case for all TypeScript types after all).

For now, since I know this is how it is, I can include it as a non-dev dependency as a workaround (though this has an implication on our build since we copy all licenses for all dependencies and publish them), but it still feels a bit off.

Tl;dr: I'm somewhat fine with the way it is, but would be great if that would be documented somewhere.

[RyanCavanaugh]

Is there some documentation about this?

Which documentation did you read? We can add it there, I guess

[DerGernTod]

I had a look at https://www.typescriptlang.org/docs/ and searched for devDependencies. Hard to say where this would belong... maybe somewhere close to Integrating with Build Tools? There's no section about the language server as far as I saw.

[RyanCavanaugh]

In general we don't document "Here's a list of bad things we don't do on purpose", since that list is more or less unbounded. Unless there's already a logical place to put this and we think it's likely to be read, I don't think any additional action required here.

Edit: On second thought I'll put it in the issue FAQ, since this has come up a couple times over the years along with the auto behavior causing some confusion

[RyanCavanaugh]

https://github.com/microsoft/TypeScript/wiki/FAQ#auto-import-heuristics-and-preferences