tsc not respecting types/typeRoots config for imported modules

Bug Report

Codebase is pulling in type declarations from the parent ../node_modules/@types/ folder, despite attempting to restrict the types and typeRoots to ignore it.

client/
  node_modules/@types/foo/ # server shouldn't ever see this!
  tsconfig.json
  
  server/
    node_modules/foo/ # server should see this as a module with no type declarations
    tsconfig.json

🔎 Search Terms

• Stop typescript from including types from parent node_modules
• Prevent typeRoots from using parent node_modules

Related Issues:

• How to block typescript 2.0 from walking up all parent directories while resolving modules? #13992
• Declarations are unexpectedly used from node_modules in parent directory #30124

The issue is very similar to the ones described above, but neither were resolved beyond saying that unwanted types could be excluded with "types": []. This only seems to work for excluding global types (e.g. @types/node) as far as I can tell, there is no way to prevent typescript pulling in types for a module that is explicitly imported. See repro for more context.

🕗 Version & Regression Information

We are seeing this problem with typescript@3.9.9, but I have created a reproduction that also confirms it on typescript@latest and typescript@next too.

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about excluding types and type roots.

💻 Code

Reproduced in repo with CI demonstrating incorrect behaviour here: https://github.com/danprince/typeroots-bug-repro

🙁 Actual behavior

The server codebase ends up including ../node_modules/@types/foo/index.d.ts as part of the compilation (through an import foo from "foo") even with "typeRoots": ["./node_modules/@types"] and "types": [].

Our current workaround is to remove the parent node_modules as part of our CI step.

We could also work around this by shadowing the declarations in the local node_modules/@types dir, or using paths hack to point typescript towards a non-existent version of the module, but it shouldn’t be that hard.

All I want is to tell tsc is to never ever look in ../node_modules/@types.

🙂 Expected behavior

Never look in ../node_modules/@types for anything. I know that conflicts with the "moduleResolution": "node" to some degree, but it should be possible to configure that as far as type declarations are concerned.

[kylecordes]

It appears to me (I don’t have a convenient isolated test case) that the problem from multiple past issues still exists also: TypeScript looks up to ../node_modules/@types/ for global types, no matter what combination of typeRoots, types, etc. is configured. It’s a significant problem with manually or automatically hoisted dependencies in a monorepo.

[danprince]

Understood. Thanks!

Our use case here is probably too specific to ever be worth changing the module resolution behaviour, but I could definitely see it being worth an additional note in the docs.

I had been thinking that the general concept of the node_modules/@types directory was fully configurable with typeRoots, rather than being a distinct part of module resolution.