When using `type` to define shape of function, `this` context setting doesn't work

[ffxsam]

TypeScript Version: 2.9.1-insiders.20180525

Search Terms:
function type this

Code

interface PasswordReset {
    working: string;
}

type Validator = (
  this: PasswordReset,
  rule: any,
  value: any,
  callback: (error?: Error) => void
) => string;

const someFunc: Validator = function(rule, value, callback) {
    console.log(this.working === true);
    return 'OK';
};

interface OtherInterface {
    working: string;
}

function thisWorks(this: OtherInterface, name: string) {
    console.log(this.wr === true); //works as expected
}

Expected behavior:
There should be contextual awareness of what interface 'this' refers to.

Actual behavior:
'this' is shown as type 'any' in someFunc func

Playground Link:
Link

Related Issues:

[DanielRosenwasser]

Arrow functions don't introduce their own this, so TypeScript is warning you that this is getting resolved globally.

[DanielRosenwasser]

Sorry, depending on if you run with noImplicitThis on, you may get a warning. Otherwise, we are more lenient. I filed #25977 so we can give a better error message when you do run with stricter settings.

[ffxsam]

My mistake, you probably saw before I edited the code and got rid of the arrow func. It works as intended.

[typescript-bot]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.