TS importModuleSpecifier could work better for lerna monorepos with libs only

[lgraziani2712]

TS Template added by @mjbvz

TypeScript Version: 3.8.0

Search Terms

• importModuleSpecifier
• auto import
• mono repo / monorepo

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Related issue: #36181 (I thought was something related to TS itself, but maybe is not).

Right now, the typescript.preferences.importModuleSpecifier auto option only uses relative paths for files nearer to the actual file than the basePath configuration file. But this isn't the best approach for a monorepo full with libs.

I only want to have aliases on imports from other lib folders, but I want to keep every import within a lib as relative imports. The problem is, VSCode suggestions sometimes adds the alias to imports within files of the same lib. When I build and publish everything as is, the service using that lib will crash because doesn't understand the alias.

Thank you in advance!

[mjbvz]

Can you provide a small example project that shows what doesn't work today and explain the expected behavior?

[lgraziani2712]

Sorry for the delay. Here is the repo: https://github.com/lgraziani2712/vscode-88977

Here is a comment in the built file: lgraziani2712/vscode-88977@07e82a9#r37005671

[mjbvz]

Moving upstream for feedback from TS team

[Ore4444]

I'm having the same issue.
compilerOptions.baseUrl in my project tsconfig is set to root of monorepo modules.
In every module tsconfig, I have: compilerOptions.outDir = "lib" and compilerOptions.rootDir = "src"
I don't have a baseUrl in module tsconfigs which is what causes the mismatch of relative imports (i have exactly the same symptoms as #36181).
If I add compilerOptions.baseUrl = "src" to a module tsconfig, it does solve the issue of doing move refactoring, but for some reason tsc fails with lots of TS2307. Now none of my compilerOptions.paths are resolved for that module.
The difference between baseUrl and no baseUrl can easily be verified by moving a folder or renaming a file with webstorm.
Seems like when compilerOptions.baseUrl is set in a composite project, compilerOptions.paths of parent tsconfig stops having a effect.

I've had this issue since the beginning of my monorepo 1.5 years ago. Finally this issue gave me a direction. I'd love to give more context if that would help.

More issues I found that might be related: #36235, #35768, #20110

[andrewbranch]

@Ore4444 what you’re describing sounds like a separate issue than the original post here. Are you able to provide an example repo demonstrating your problem?

If I add compilerOptions.baseUrl = "src" to a module tsconfig, it does solve the issue of doing move refactoring, but for some reason tsc fails with lots of TS2307. Now none of my compilerOptions.paths are resolved for that module.
The difference between baseUrl and no baseUrl can easily be verified by moving a folder or renaming a file with webstorm.
Seems like when compilerOptions.baseUrl is set in a composite project, compilerOptions.paths of parent tsconfig stops having a effect.

Actually, this sounds like expected behavior. paths are resolved relative to baseUrl, so if you override baseUrl in a child tsconfig, that changes how the parent paths resolve—specifically, in this case, all those paths will fail to resolve.

Most of what’s described in this issue, including 100% of the problem in @lgraziani2712’s example repo, is essentially a duplicate of #31869, and would be solved by implementing that proposal. It does leave open the issue of trying to use a common set of paths in a base tsconfig, though, because each composite project will be able to resolve itself with its unrooted paths entry. Example:

tsconfig.base.json: "paths": { "lib-a": ["packages/lib-a"], "lib-b": ["packages/lib-b"], "lib-c": ... }
packages/
  app/
    tsconfig.json (extends base, references all libs)
  lib-a/
    tsconfig.json (extends base, references b and c)
  lib-b/
    tsconfig.json (extends base, no references)
  lib-c/
    ...

The intention is probably:

• the app package can reference any lib by its path mapping - ✔️
• the lib-a package can reference lib-b and lib-c by their path mappings - ✔️
• the lib-a package cannot reference itself by the "lib-a" path mapping - ❌

To accomplish this, even if #31869 is implemented, each project would need its own paths setting to avoid the pitfall of being able to reference itself. I hoped this would be solvable already by letting lib-a/tsconfig.json specify "paths": { "lib-a": [] }, but paths in a child tsconfig completely overwrites paths in an extended config instead of merging.