False positive: UseCheckOrError

[BraisGabin]

Expected Behavior

This code should not be flagged

val lambda: (Throwable) -> Unit = {
  if (it is IllegalStateException) {
    println("something")
  } else {
    throw IllegalStateException(it)
  }
}

Observed Behavior

It is flagged

Context

Replacing throw IllegalStateException(error) with error(error) changes the behaviour so it should not be flagged.

Your Environment

• Version of detekt used: 1.6.0

[schalkms]

Okay. Have you tried to rewrite the lambda to something like this?

val lambda: (Throwable) -> Unit = {
  check(it is IllegalStateException) { throw IllegalStateException(it) } // or just { it }
  println("something")
}

[BraisGabin]

My snipped was just a simplification. The point is that throw IllegalStateException(it) is not the same as error(it) unless it is a String. We need type resolution to fix this problem.

[schalkms]

@BraisGabin mine was also about simplification. The whole rule is about simplification. You could use either error or check. I'm curios, what part of my code snippet didn't work for you?

[BraisGabin]

when(throwable) {
    is NumberFormatException -> println("a")
    is IllegalArgumentException -> println("b")
    is NullPointerException -> println("c")
    else -> throw IllegalStateException(throwable)
}

The code is something like this but with domain exceptions (users not logged, user disabled, user no verfied...).

[arturbosch]

The basic rule part could check for a string literal argument.
The advanced part when BindingContext is set could resolve the type ^^.

[schalkms]

Now I see the issue. error() and check() don't provide an overload for wrapping exceptions. That's unfortunate. To solve this problem, one needs to use the BindingContext and check for exactly 1 argument of type String.