Rule request: forbid control flow statements in finally

Adding a return statement in a finally block is a very confusing thing. Thrown errors get ignored, return statements in try blocks get ignored, and your mind explodes.

I’d love to have a rule to forbid this. Especially now that we’re having async/await.

examples:

try {
  return 1;
} catch(err) {
  return 2;
} finally {
  return 3;
}
// > 3

try {
  throw new Error;
  return 1;
} catch(err) {
  return 2;
} finally {
  return 3;
}
// > 3

[nzakas]

“Control flow” refers to anything that changes where execution flows, Including if, while, etc., so it’s a bit broad for this use case.

How about no-unsafe-finally?

[BYK]

I’m 👍 since this is a core language issue and a pitfall quite easy to fall into without realizing consequences. We should add this to eslint:recommended too IMO.