no-unreachable: shouldn't be triggered by a semicolon after switch

What version of ESLint are you using? v2.11.0

What parser (default, Babel-ESLint, etc.) are you using? Occurs with either espree or babel-eslint.

Please show your full configuration: Anything with no-unreachable enabled…

What did you do? Please include the actual source code causing the issue.

This triggers 5:4 error Unreachable code no-unreachable

function foo(bar) {
  switch (bar) {
    default:
      return bar;
  };
}

This doesn’t…

function foo(bar) {
  switch (bar) {
    default:
      return bar;
  }
}

(the only difference being in the semicolon after the switch)

What did you expect to happen?

I would have expected no-unreachable not to trigger on semicolon… (there’s other rules for that 😃).

What actually happened? Please include the actual, raw output from ESLint.

5:4 error Unreachable code no-unreachable

[platinumazure]

@mysticatea Isn’t it true that someone could turn off no-extra-semi though? Then they would get no warning at all, if EmptyStatements are allowed by no-unreachable.

Personally, I see nothing wrong with having two lint errors show up for two different issues. The unreachable-ness of the semicolon has nothing to do with the fact that it’s an unnecessary/empty statement; the emptiness of the statement has nothing to do with the fact that it is unreachable.

Personally I would say this is working as designed and we don’t need to enhance it. I think we could enhance no-unreachable to have a different error message for EmptyStatements, to make it less confusing. But I don’t think we shouldn’t warn.

[platinumazure]

I’m not sure I understand why you think you need the semicolon after switch in the first place. It’s completely unnecessary and it’s not allowed by the language (that is, a SwitchStatement in the grammar does not allow an optional semicolon like simple statements do, and any semicolon you do place is unambiguously an empty and unnecessary statement). On Jun 6, 2016 11:10 AM, “Martin Hradil” [e-mail] wrote:

Exactly, I do understand that from the parser’s standpoint it really is an unreachable statement. But it means there’s currently no way to allow semicolon after switch and get no warnings while still wanting to be warned about nonempty unreachable statements…

Maybe just adding an ignoreEmpty option to no-unreachable would work? (and yes, I’m willing to implement that 😃)

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