[no-invalid-void-type] Intersection with never should be allowed

[jens-duttke]

Repro

{
  "rules": {
    "@typescript-eslint/no-invalid-void-type": "error"
  }
}

function foo (): void | never {
    throw new Error('Test');
}

Expected Result

That the no-invalid-void-type does not complain about the void | never union.

Actual Result

void is only valid as a return type or generic type variable [Error/@typescript-eslint/no-invalid-void-type]

Versions

package	version
@typescript-eslint/eslint-plugin	2.30.0
@typescript-eslint/parser	2.30.0
TypeScript	3.9.0-dev.20200419
ESLint	6.8.0
node	13.6.0
npm	6.14.4

[bradzacher]

How come you're using void | never?
TypeScript collapses the never out of the return type, so it's like it's never even there.

Is it purely for documentation that the function may throw?

[jens-duttke]

@bradzacher: Yes, right now it's purely for documentation. But I also have the hope that some day, either TypeScript or an ESLint plugin does something useful with it. ;-)

[sinyovercosy]

This should be an easy fix once #1960 is merged - all that should be needed is to add never as a valid member type to the isValidUnionType function.