(no-trailing-whitespace) flags leading empty line as error

[itanex]

Bug Report

• TSLint version: 5.11.0
• TypeScript version: 2.9.2
• Running TSLint via: CLI / (Visual Studio - does not show this error)

TypeScript code being linted

Multiple classes with a leading line that is empty. This line only contains line endings when analyzed (e.g. \r\n)

export class User {
    userName: string;
}

with tslint.json configuration:

{
  "defaultSeverity": "error",
  "extends": "tslint:recommended",
  "jsRules": {},
  "rules": {
    "quotemark": [
      true,
      "single",
      "avoid-escape"
    ],
    "member-access": [
      true,
      "no-public"
    ],
    "object-literal-sort-keys": [
      false
    ],
    "object-literal-shorthand": [
      true,
      "never"
    ],
    "ordered-imports": [
      false
    ],
    "trailing-comma": [
      true,
      {
        "esSpecCompliant": true
      }
    ]
  },
  "rulesDirectory": [],
  "linterOptions": {
    "exclude": [
      "src/test.ts",
      "src/main.ts",
      "src/polyfills.ts"
    ]
  }
}

Actual behavior

Multiple results identical to the following

ERROR: ClientApp/src/app/models/ActionItem.ts:1:1 - trailing whitespace

Expected behavior

No results generated

[JoshuaKGoldberg]

@itanex thanks for the bug report! I tried reproducing this locally but couldn't. Is the project you're experiencing this with open source, or failing that, could you upload ActionItem.ts or another file it's happening on?

One guess would be that the file has some \r\n lines and some \n.

[itanex]

@JoshuaKGoldberg Yes the file line endings are windows line endings (\r\n).

I have uploaded the ActionItem.ts file along with the tslint.json.

Please note that the ActionItems.ts file is generated through TypeWriter, so simply deleting the line is not a viable option, as this would need to be done anytime the file is regenerated.

https://github.com/itanex/random-files/tree/master/tslint-bugs/4518

[JoshuaKGoldberg]

This was a fun one to debug! The root issue is that getLineRanges from the tsutils library is reporting that the first line in the ActionItem.ts file has a contentLength of 1 instead of 0. Filed ajafff/tsutils#94 to track.

Accepting PRs to fix in this library in the meantime, since even if tsutils releases a version with a fix, TSLint still accepts older versions of tsutils.