Rule Suggestion: Disallow comma operator in switch 'case' clauses

[RyanCavanaugh]

let arr = [];
switch(arr.length) {
  case 0, 1:
    return 'zero or one';
  default:
    return 'more than one';
}

This doesn't behave as expected (see microsoft/TypeScript#10802) even though it looks like it might

[06needhamt]

This would of saved me from hours of pain as shown in microsoft/TypeScript#10802 (comment)

[IllusionMH]

I've started looking on this and I'm curious: should new rule enforce more strict checks for expressions in case clauses with set of options?
For example:

• literals-only - allows only literals
• no-comma - disallows coma operator in expressions
• no-call-expressions - option which disables call expressions
• no-binary-expressions - option which disables binary expressions

@jkillian, @RyanCavanaugh, @adidahiya, what do you think?

[jkillian]

I can't think of a case where I've wanted an complex switch pattern. However, literals-only might be a bit of overkill, as you couldn't do this:

switch (someVar) {
    case SomeEnum.VALUE_1:
        ...
}

[RyanCavanaugh]

We'll likely take microsoft/TypeScript#10814 so probably this rule won't be needed

[jkillian]

I'm going to close this issue since TS is likely picking this up. If things change on the TS side (or even if it's just going to be a long time before this is implemented) this would be a great rule and we should implement it