space-before-function-paren doesn't detect anonymously exported function correctly

[Ky6uk]

Bug Report

• TSLint version: v5.5.0
• TypeScript version: v2.4.1
• Running TSLint via: Atom / CLI

TypeScript code being linted

export default function () {
  return;
}

with tslint.json configuration:

{
  "extends": "tslint:latest",

  "rules": {
    "ordered-imports": false,
    "object-literal-sort-keys": false,
    "only-arrow-functions": false,

    "interface-name": [true, "never-prefix"],
    "quotemark": [true, "single", "jsx-double"],
    "trailing-comma": [true, "never"],

    "space-before-function-paren": [true, {
      "anonymous": "always",
      "asyncArrow": "always",
      "constructor": "never",
      "method": "never",
      "named": "never"
    }]
  }
}

Actual behavior

Got the error Spaces before function parens are disallowed.

Expected behavior

No error expected here.

[ajafff]

exported function declarations cannot be anonymous, the grammar doesn't allow that. You should get an error from the typescript compiler. That's why tslint treats this function as "named".

[Ky6uk]

@ajafff but this is correct TS code with some compiler flags. I think TSLint should handle that. Correct me if I am wrong.

[ajafff]

What flag(s) do you mean? I haven't noticed anything like this before...

[Ky6uk]

Sorry. That's working w/o any flags. I updated my first message.

https://www.typescriptlang.org/docs/handbook/modules.html

Classes and function declarations can be authored directly as default exports.
Default export class and function declaration names are optional.

[ajafff]

Yeah, the default export makes sense. This is a bug. It should be handled like other anonymous functions.

[IllusionMH]

Looks like I found fix, but can't run yarn test on Windows at this moment.
Will send PR in the evening.