Fix when for parameterized types on Scala 2

It already works on Scala 3. Although in the general case it's eliminated by erasure, we would get a warning because it's implemented as a pattern match.
softwaremill · May 10, 2023 · de9bfc3 · de9bfc3
1 parent 55a0337
commit de9bfc3
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Showing 2 changed files with 18 additions and 2 deletions.
diff --git a/quicklens/src/main/scala-2/com/softwaremill/quicklens/QuicklensMacros.scala b/quicklens/src/main/scala-2/com/softwaremill/quicklens/QuicklensMacros.scala
@@ -119,7 +119,7 @@ object QuicklensMacros {
 
     sealed trait PathElement
     case class TermPathElement(term: c.TermName, access: PathAccess, xargs: c.Tree*) extends PathElement
-    case class SubtypePathElement(subtype: c.Symbol) extends PathElement
+    case class SubtypePathElement(subtype: c.Type) extends PathElement
     case class FunctorPathElement(functor: c.Tree, method: c.TermName, xargs: c.Tree*) extends PathElement
 
     /** Determine if the `.copy` method should be applied directly or through a match across all subclasses (for sealed
@@ -168,7 +168,7 @@ object QuicklensMacros {
           val access = determinePathAccess(parent.tpe.typeSymbol)
           collectPathElements(parent, TermPathElement(child, access) :: acc)
         case q"$tpname[..$_]($parent).when[$tp]" if typeSupported(tpname) =>
-          collectPathElements(parent, SubtypePathElement(tp.tpe.typeSymbol) :: acc)
+          collectPathElements(parent, SubtypePathElement(tp.tpe) :: acc)
         case q"$parent.$method(..$xargs)" if methodSupported(method) =>
           collectPathElements(parent, TermPathElement(method, DirectPathAccess, xargs: _*) :: acc)
         case q"$tpname[..$_]($t)($f)" if typeSupported(tpname) =>

diff --git a/quicklens/src/test/scala/com/softwaremill/quicklens/ModifyWhenTest.scala b/quicklens/src/test/scala/com/softwaremill/quicklens/ModifyWhenTest.scala
@@ -17,6 +17,14 @@ object ModifyWhenTestData {
 
   val zoo = Zoo(List(dog, cat))
   val olderZoo = Zoo(List(olderDog, olderCat))
+
+  trait MyOption[+A]
+  case class MySome[+A](value: A) extends MyOption[A]
+  case object MyNone extends MyOption[Nothing]
+
+  val someDog: MyOption[Dog] = MySome(Dog(4))
+  val someOlderDog: MyOption[Dog] = MySome(Dog(5))
+  val noDog: MyOption[Dog] = MyNone
 }
 
 class ModifyWhenTest extends AnyFlatSpec with Matchers {
@@ -42,4 +50,12 @@ class ModifyWhenTest extends AnyFlatSpec with Matchers {
       )
       .using(_ + 1) shouldEqual olderZoo
   }
+
+  it should "modify a field in a subtypes (parameterized)" in {
+    someDog.modify(_.when[MySome[Dog]].value.age).using(_ + 1) shouldEqual someOlderDog
+  }
+
+  it should "ignore subtypes other than the selected one (parameterized)" in {
+    noDog.modify(_.when[MySome[Dog]].value.age).using(_ + 1) shouldEqual MyNone
+  }
 }