TS type check is checking my lib incorrectly when added it to an App project. about nx HOT 1 CLOSED

Thanks for reporting this!

This is the expected behavior for TypeScript with your setup. The my-app project depends on the source code of products and when you run tsc -p apps/my-app/tsconfig.app.json, the TS compiler creates a ts.Program for that configuration file. It doesn't use any other configuration file unless is extended or referenced. In this case, it extends the tsconfig.base.json and it doesn't reference any other configuration file. Therefore, every file included in the ts.Program will be processed with the apps/my-app/tsconfig.app.json configuration (plus the merged config from the extended tsconfig.base.json). The library source code is part of the ts.Program because:

• the ts.Program rootDir is the root of the workspace (specified in tsconfig.base.json)
• it's imported from the application using the path mapping @nx-test/products which is configured to resolve libs/products/src/index.ts (a file inside the rootDir)

So, that's why tsc is processing libs/products/src/lib/products.tsx when running for the apps/my-app/tsconfig.app.json project. Please note that, as mentioned, this is expected TypeScript behavior based on the configuration you shared in the reproduction.

TypeScript has a way to effectively split source code into multiple "projects", which is using project references and tsc -b. By configuring your whole TypeScript setup like a solution where each tsconfig.json file is considered and independent project, tsc can build them independently. An issue with it is that tsc -b is a "build"-only command. You'll always need to at least emit the declaration files.

from nx.