Fatal on error has or is using private name on an already export-ed Class

[huan]

Bug Report

• TSLint version: 5.7.0
• TypeScript version: 2.4.2
• Running TSLint via: CLI

TypeScript code being linted

import {
  widget,
  Widgets,
}             from 'blessed'

declare module 'blessed' {
  namespace widget {
    class Image extends Widgets.ImageElement {}
  }

  namespace Widgets {
    interface Border {
      top?:    boolean,
      bottom?: boolean,
    }
  }
}

with tslint.json configuration:

tslint --project tsconfig.json --type-check 

Actual behavior

[ts] 'extends' clause of exported class 'Image' has or is using private name 'Widgets'.

However, ts-node & tsc can run the code without any problem.

Expected behavior

Should not show private name Widgetsbecause it's alreadyexport`-ed.

[ajafff]

The quick fix for your problem is omitting --type-check. It's no longer needed to use type checked rules.
You will then no longer see any compile errors in the lint output.

[huan]

Yes, that's what I did at last.

But what do you mean "it's no longer needed", had --type-check deprecated?

It's no longer needed to use type checked rules.

[ajafff]

--type-check is not deprecated yet. It's just no longer needed for typed rules to work, --project is sufficient for that.

It probably will be deprecated. It's no longer useful and we frequently get bug reports about it. I don't think it's worth keeping it around.

[huan]

It's a good news that --project is sufficient for checking.

Thanks for the explanation!

[trusktr]

I've opened a request to fix issues like these in TypeScript by bringing declaration files to parity with language features. microsoft/TypeScript#35822