Example:

// @Filename: /tsconfig1.json
{
  "compilerOptions": {
    "strictNullChecks": true
  }
}

// @Filename: /tsconfig2.json
{
  "compilerOptions": {
    "noImplicitAny": true
  }
}

// @Filename: /tsconfig.json
{
  "extends": ["./tsconfig1.json", "./tsconfig2.json"]
  "files": ["./index.ts"]
}

// @Filename: /index.ts
function f(x) {} // noImplicitAny error
let y: string;
y.toLowerCase(); // strictNullChecks error

Andrew Branch (@andrewbranch) the compiler tests are hard to add with tsconfig. https://github.com/microsoft/TypeScript/pull/50403/files#diff-0556827a3985d4ffd3ed2e51ac63c9d86ba98ab41dca5c7711fb2750188cbe8a shows the test case where multiple tsconfigs are working together ? https://github.com/microsoft/TypeScript/pull/50403/files#diff-97bc6a439e0f02498deab0f7c919e4e7a2f06c6b4832fd2fc7b042f56b141ff9R111 baseline.

While said that we could add test in non watch mode as well.

I saw that baseline, but I couldn’t find any indication in the baseline that the options in the extended configs were relevant. I was looking for a strictNullChecks or noImplicitAny error but didn’t see any. Maybe I missed it in the noise.

There are plenty of compiler tests with tsconfig files, but I don’t know if there are subtle gotchas with them.

navya9singh you probably want to add test like https://github.com/microsoft/TypeScript/blob/main/src/testRunner/unittests/tsc/forceConsistentCasingInFileNames.ts with the contents of test files as shown by Andrew Branch (@andrewbranch) for better clarity

TypeScript Bot (@typescript-bot) pack this

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the tarball bundle task on this PR at bb0ae2f. You can monitor the build here.

Hey Daniel Rosenwasser (@DanielRosenwasser), I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/139933/artifacts?artifactName=tgz&fileId=43D4A075BE928283C15303888F67D4786C1B8B67071DA37D39B422AFBEEC049702&fileName=/typescript-5.0.0-insiders.20221207.tgz"
    }
}

and then running npm install.

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@5.0.0-pr-50403-6".;

It looks like some changes landed in main that require you to update something in your unit tests. I’m guessing it’s #51798. You’ll want to manually merge main into this branch and then take a look at those test files that no longer build, using Sheetal’s PR as a reference for how to update them.

Very cool

Just a heads up if you're sharing a tsconfig from a package. It seems typescript@4.9.5 was not restricted by the exports from the package.json file. It is now with @typescript@5.0.3.

The tsconfig.json file not found error was the last error when running tsc.

In my case, it was also causing eslint (with @typescript-eslint/parser) to fail with out of memory errors. Since we run eslint before tsc, it was a few tries before I decided to skip eslint and run tsc and was able to find the problem.