Fix erroneous unused import flagging on custom destructure operators #142
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marked as unused imports
- Devs can write custom componentN operators in order to allow
destructuring blocks of > 5 values, i.e.
inline operator fun <T> component6 = get(5)
which allows the following (which is NOT possible without the above
extension method):
val (one, two, three, four, five, six) = someList
^--- component6() is imported to
make this possible
- In order to avoid marking these imports as unused we can ignore all
imports that match componentX (where X is any number)
JelloRanger
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Hi Jacob. Thank you for the PR! It's perfect. ❤️ |
shyiko
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Feb 27, 2018
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I noticed a bug with the unused import rule when I initially integrated in KtLint into one of my projects. It erroneously detected custom componentN operators as unused (which the auto formatter ended up removing and breaking my build :()
The Kotlin std library by default only provides
component1()up tocomponent5(), meaning that you can only destructure up to 5 values by default. See https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/index.html and search for "component5" for referenceSo if someone wants to destructure six values, i.e.:
(one, two, three, four, five, six) = someList... the IDE will throw an error since
component6()doesn't exist. To get around this you can write your own component6() method pretty easily:inline operator fun <T> List<T>.component6() = get(5).. and when this method is imported it's flagged by KtLint as unused since the unused import rule only checks for the default destructure methods (component1...5()).
To solve this I added a regex that'll match against componentN (where N is some number) and ignore the normal unused import checking.
I'm also open to suggestions if you think there is a better way of handling this case.