Tuple modification fails with Scala 3

[OndrejSpanel]

I have added unit tests which demonstrate tuple modification fails with Scala 3.

The test itself is very simple and works fine with Scala 2:

    val tuple4 = (0, 1, 2, 3)
    val modified = tuple4.modify(_._3).setTo(3)
    modified shouldBe(0, 1, 3, 3)

The error is:

Exception occurred while executing macro expansion.
java.util.NoSuchElementException: head of empty list
	at scala.collection.immutable.Nil$.head(List.scala:662)
	at scala.collection.immutable.Nil$.head(List.scala:661)
	at com.softwaremill.quicklens.QuicklensMacros$.termMethodByNameUnsafe$1(QuicklensMacros.scala:142)
	at com.softwaremill.quicklens.QuicklensMacros$.$anonfun$38$$anonfun$1(QuicklensMacros.scala:173)
	at scala.collection.immutable.Map$Map1.getOrElse(Map.scala:250)
	at com.softwaremill.quicklens.QuicklensMacros$.$anonfun$38(QuicklensMacros.scala:173)
	at com.softwaremill.quicklens.QuicklensMacros$.$anonfun$adapted$1(QuicklensMacros.scala:174)
	at scala.collection.immutable.Range.map(Range.scala:59)
	at com.softwaremill.quicklens.QuicklensMacros$.caseClassCopy$1(QuicklensMacros.scala:174)

I will try to learn more, or develop a fix, but I cannot promise when.

[OndrejSpanel]

There is a difference between tuple and case class in caseFields. Case class with two items:

Fields of class Pair: List(val a, val b)

Tuple with two items:

Fields of class Tuple2: List(method _1, val _1 , method _2, val _2 )

Note: the name of the val field is not _1, but _1 (with a trailing space).

[KacperFKorban]

Maybe using primaryConstructor to find the index might be easier. I can push a possible fix here if you want.

[OndrejSpanel]

I can push a possible fix here if you want.

Sure.

I was experimenting with caseClassCopy, but I was unable to find any working solution, and frankly, I had little idea what am I doing. I can help making the solution work / completing it if necessary (and if I am able to).

[KacperFKorban]

Couldn't push here, so created OndrejSpanel#6

[OndrejSpanel]

Great, I have merged your commits here and all tests passed, therefore this looks promising. Passing for a review from higher powers.

[adamw]

Thanks! :)