💡 an issue with detecting unnecessary files in the monorepo project.

[vincent890120]

Suggest an idea for Knip

I ran into a problem while using knip detection in a monorepo project.
Let me give you an example:
The project comprises two sub-packages, app and infrastructure, where app relies on infrastructure's baseMethod.
When I import the baseMethod() from '@infrastructure/lib/base' in app and run 'knip --production', the file 'packages/infrastructure/lib/base.ts' is flagged as unnecessary.
But when I import the baseMethod from 'infrastructure/lib/base', knip correctly identifies 'packages/infrastructure/lib/base.ts' as a necessary file. I'm wondering, why does the presence of the '@' symbol cause this misidentification?
Here's the layout of the project structure.

Can you assist me? Could there be an issue with how I'm using knip?

[vincent890120]

This is what I get when I run knip.

[webpro]

The answer is here: https://knip.dev/reference/faq#why-cant-i-use-path-aliases-to-reference-other-workspaces

[vincent890120]

The answer is here: https://knip.dev/reference/faq#why-cant-i-use-path-aliases-to-reference-other-workspaces

I set up the paths attribute in knip.json, but it still fails to properly recognize the references from monorepo.

I attempted to debug some of the kinp's source code and discovered that when there are multiple workspaces, each workspace corresponds to a principal. When the principal.addProjectPath(projectPath) is executed, it only adds the projectPath of the current workspace. However, when it comes to determining the usefulness of a file, it compares it with sourceFiles and projectPaths. I've logged some of the results.

As you can see, the sourceFile analysis indicates that "/Users/vincent/Project/web/Demo/anpoi-monorepo/packages/infrastructure/lib/base.ts" is a useful file. However, since this file is not included in the projectFiles, it's being identified as a useless file. Is there any solution to this issue?

[webpro]

The recommendation is to use dependencies from package.json#dependencies, not knip.json#paths

Using tsonfig.json#compilerOptions.paths is valid, it's just something that Knip doesn't handle well.

By the way, there's --isolate-workspaces to use one principal per workspace (but it's not a solution here).

[webpro]

Looked at the implementation again and came to the same conclusion, which I've now tried to document a bit better: https://knip.dev/guides/handling-issues#typescript-path-aliases-in-monorepos ↔ https://knip.dev/reference/faq#why-cant-i-use-path-aliases-to-reference-other-workspaces

[webpro]

🚀 This issue has been resolved in v5.46.0. See Release 5.46.0 for release notes.

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