Is there any rule that would allow enforcing a return value (from a function marked with an annotation) wasn't ignored?

Could you elaborate with a code snippet please?

for example, the following function:

fun Byte.putBit(bitPos: Int, isSet: Boolean): Byte {
    return if (isSet) {
        (this.toInt() or (0b10000000 ushr bitPos)).toByte()
    } else {
        (this.toInt() and (0b10000000 ushr bitPos).inv()).toByte()
    }
}

In Android there is https://developer.android.com/reference/androidx/annotation/CheckResult

ah cool, i couldn't find a bug. voted.

Thanks for helping out @diego-gomez-olvera!

No problem

so is there any rule for an ignored return value?

would it be possible to add one?

Yes, you could add such a rule to detekt. You would need to use type and symbol solving, which is shown in the following example. https://github.com/arturbosch/detekt/blob/master/detekt-rules/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UselessCallOnNotNull.kt If you have a strong need for this rule, you can certainly re-implement this in detekt and contribute back to the project.

Thanks for the reference. Do you think it would be something that would belong in detekt? I definitely think it would be nice to have. Especially if an annotation was used, calling a method which had a

CheckResult

(or whatever) annotation and not using its return would almost definitely indicate a bug.

Do you think it would be something that would belong in detekt?

Yeah, it would be a nice add-on with a very low priority, since there are existing solutions. There are many other features, which have way higher priority. We rely on contributions from our awesome community for such rules. Of course we try to assist as much as possible.

Ok, good to know. One other question: does detekt introduce any of its own annotations? One decision would be whether or not to warn on ALL functions who return a value which isn't saved vs. just those with an annotation. Now that I've typed that out, though, perhaps doing it for all cases is best. EDIT: And the rule could be disabled by users for those cases where it shouldn't warn.

One decision would be whether or not to warn on ALL functions who return a value which isn't saved vs. just those with an annotation

We handle this with configuration options. For example:

LongParameterList:
    active: true
    threshold: 6
    ignoreDefaultParameters: false

Ok, I more had in mind using https://arturbosch.github.io/detekt/suppressing-rules.html

And the rule could be disabled by users for those cases where it shouldn't warn.

Yes. Detekt supports the

@Suppress

annotation.

👍 Yup, thanks.

@bbaldino could you please also create an issue for this on GitHub with all the written information copied from Slack? This would certainly help to better track this feature.

Sure

This is a vey cool rule and fits perfectly in the potential-bugs rule set, thanks for contributing. I will try to come to your PR later that week.