[ no-constant-condition] should validate 'void' too

[pvamshi]

Request type : Enhancement

Rule : no-constant-condition

What version of ESLint are you using?
2.5.1

What parser (default, Babel-ESLint, etc.) are you using?
default

Please show your full configuration:

{
  "rules": {
    "no-constant-condition": 2   // disallow use of constant expressions in conditions
  }
}

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

if(void x){}
if (void x === void x){}

What did you expect to happen?
Error as it is a constant condition

What actually happened?
No error

As discussed in #5228 & #5696

[ilyavolodin]

Sounds reasonable to me. Although I think the primary case should be:

if (void) {}

[dead-claudia]

@ilyavolodin You mean if (void foo) {}? 😉

[ilyavolodin]

Yes I do:-)

[vitorbal]

I would love to tackle this one if it gets accepted!

[michaelficarra]

There's also some other missing expression types in the isConstant function. ConditionalExpression stands out to me. I think this issue should be about generally expanding that function as best we can.

[vitorbal]

Should it really be addressed in this issue? I have a PR ready for the void case otherwise.

[alberto]

Is anyone championing this? @eslint/eslint-team

[platinumazure]

I count one 👍 (@ilyavolodin, maybe a stretch). I will add one more 👍.

@vitorbal, you could champion or add 👍. Then we need whatever you don't do. 😄

@michaelficarra I think we should create a separate issue for the problem you've brought up.

[vitorbal]

@alberto @platinumazure thanks for the ping! I am willing to champion this change and I've already got a PR almost ready, just in need of a rebase.

I agree that we should open a separate issue for the extra checks.

[nzakas]

I'll 👍

@vitorbal as the champion, you should secure one more definitive 👍 and then you can mark as accepted.

[alberto]

👍

[vitorbal]

Thanks all, I will get around to finishing this by the end of this week!