tsc correctly raises TS errors - tsup builds and ignores errors

If I run pnpm exec tsc --noEmit then I get 5 errors. If I run pnpm exec tsup src/index.ts --dts then I 0 errors.

I realize I don’t provide enough info here but first I just want to ask if this isn’t a bug?

[await-ovo]

I can reproduce it with this:

// index.ts
import { bar } from "./bar"

export function foo() {
  bar()
}

// bar.ts
export const bar = () => {}

export function unused_error_function() {
  let a: string = 1 // <-- type error
  return a
}

Seems rollup-plugin-dts doesn’t type check unused export

@OmgImAlexis did you have the same code pattern?

it seems that rollup-plugin-dts doesn’t type check bar.ts at all, code like this will also not throw errors:

// index.ts
import { bar } from "./bar"

export function foo() {
  bar()
}

// bar.ts
export const bar = () => {
  let b:string = 1 // <-- type error
  return b;
}

Here are my thoughts:

rollup-plugin-dts use typescript’s api(program.emit) generate declaration file for index.ts, then use Rollup bundle the generated code. dts for index.ts will be :

export declare function foo(): void;

This has nothing to do with ./bar.ts, so Rollup will not resolve, tranform ./bar.ts will also not do type checking~

I’m not sure if it is a bug of rollup-plugin-dts, seems that the recommended way to use this plugin is with generated dts with tsc(https://github.com/Swatinem/rollup-plugin-dts/issues/41#issuecomment-503550069) ~

Can we use tsc generate declaration files and then use rollup-plugin-dts or api-extractor bundle dts files? this also should be no problem with type check 😃

[shivam123425]

I ran into the same problem 😦 I had to use tsc and tsc-watch package and run tsup in its success callback. The dev and build step looks like this:

"scripts": {
    "build": "tsc && tsup --env.NODE_ENV production",
    "dev": "tsc-watch --onSuccess \"tsup --env.NODE_ENV production\""
}