Feature Request: allow exclusion of node_modules when skipLibCheck is false

Search Terms

skipLibCheck node_modules, skipLibCheck

All I’ve found is this lonely SO post. As that user notes, there are a lot of posts around Angular and excluding node_modules from typechecking on one dimension or another, but they all end up suggesting turning on skipLibCheck.

Suggestion

Allow the exclusion of files in node_modules (regardless of their inclusion in the Project) from lib checking when skipLibCheck is set to false.

Use Cases

I want to be able to typecheck my own .d.ts files without being responsible for all of the types my dependencies import. My local configuration is strict and it may be that the types provided in my packages were not intended strictly, or other configurations in my local JSON run up against the way other packages have written theirs.

I am assuming the counterargument is that it’s all-or-nothing, but then why do .ts files that rely on .d.ts files typecheck fine when my .d.ts files are not typechecked? Can’t that behavior be applied to definitions in node_modules?

Examples

Not sure how to show an example here. I would like to be able to run tsc --noEmit on my codebase and get errors for my own definitions files without having a bunch of noise from unfixable errors in node_modules/@types etc.

Checklist

My suggestion meets these guidelines:

• This wouldn’t be a breaking change in existing TypeScript/JavaScript code
  If implemented as some additional flag?
• This wouldn’t change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn’t a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript’s Design Goals.
  I think so?

[RyanCavanaugh]

I’d propose a new setting

`“skipLibCheck”: “external”

which says that any .d.ts file in your files or include pattern is checked, but any .d.ts file that gets into your program via other means is not (e.g. node_modules imports, output .d.ts files from upstream project references)

Thoughts?

[RyanCavanaugh]

It sounds like you’re asking for the opposite - a mode for skipLibCheck that says only skip checking of .d.ts files from node_modules?