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Remove whitebox cast from GenIso.fields #1602

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Merged
julien-truffaut merged 1 commit into from
Jul 13, 2026
Merged

Remove whitebox cast from GenIso.fields #1602

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17 changes: 6 additions & 11 deletions macro/src/main/scala-3/monocle/macros/GenIso.scala
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
package monocle.macros

import monocle.Iso
import monocle.{Iso, PIso}
import scala.language.`3.0`
import scala.deriving.*
import scala.quoted.*
Expand Down Expand Up @@ -58,23 +58,18 @@ object GenIso {
* types in the same order as the fields themselves.
*/
@deprecated("use monocle.Iso.fields", since = "3.1.0")
transparent inline def fields[S <: Product](using m: Mirror.ProductOf[S]): Iso[S, Any] =
transparent inline def fields[S <: Product](using m: Mirror.ProductOf[S]): PIso[S, S, ?, ?] =
${ _fields[S]('m) }

private def _fields[S <: Product](e: Expr[Mirror.ProductOf[S]])(using Quotes, Type[S]): Expr[Iso[S, Any]] = {

def whitebox[A](e: Expr[Iso[S, A]]): Expr[Iso[S, Any]] =
e.asInstanceOf[Expr[Iso[S, Any]]]

private def _fields[S <: Product](e: Expr[Mirror.ProductOf[S]])(using Quotes, Type[S]): Expr[PIso[S, S, ?, ?]] =
e match {
case '{ $m: Mirror.ProductOf[S] { type MirroredElemTypes = EmptyTuple } } =>
whitebox(_unit[S](e))
_unit[S](e)

case '{ $m: Mirror.ProductOf[S] { type MirroredElemTypes = a *: EmptyTuple } } =>
whitebox(_apply[S, a](e))
_apply[S, a](e)

case _ =>
'{ monocle.internal.IsoFields[S](using $e) }.asInstanceOf[Expr[Iso[S, Any]]]
'{ monocle.internal.IsoFields[S](using $e) }
}
}
}