Test backwards compat of mirror API changes

Author: EugeneFlesselle

sbt-test/scala3-compat/defaultArgument-mirrors-3.3/app/Main.scala

@@ -0,0 +1,58 @@
+import scala.deriving.Mirror
+
+package lib {
+
+  case class NewFoo(x: Int = 1, y: Int)
+
+  object NewMirrors {
+    val mNewFoo = summon[Mirror.Of[NewFoo]]
+
+    val mOldFoo = summon[Mirror.Of[OldFoo]]
+    val mOldBar = summon[Mirror.Of[OldBar]]
+  }
+}
+
+package app {
+  import lib.*
+
+  object Main {
+
+    // defaultArgument implementation did not throw NoSuchElementException
+    def foundDefaultArgument(m: Mirror.Product): Boolean = try {
+      m.defaultArgument(0)
+      true
+    } catch {
+      case _: NoSuchElementException => false
+    }
+
+    def main(args: Array[String]): Unit = {
+
+      // NewFoo: normal case with support for default arguments
+
+      assert(NewMirrors.mNewFoo.defaultArgument(0) == 1)
+      summon[NewMirrors.mNewFoo.MirroredElemHasDefaults =:= (true, false)]
+
+      // OldFoo: does not override the defaultArgument implementation
+
+      assert(!foundDefaultArgument(NewMirrors.mOldFoo)) // Expected: since mirror of old case class
+      summon[NewMirrors.mOldFoo.MirroredElemHasDefaults =:= (false, false)] // Necessary: to be consistent with defaultArgument implementation
+
+      assert(!foundDefaultArgument(OldMirrors.mOldFoo)) // Expected: since mirror of old case class
+      summon[scala.util.NotGiven[OldMirrors.mOldFoo.MirroredElemHasDefaults <:< (Boolean, Boolean)]] // reference to old mirror doesn't have any refinement
+      summon[OldMirrors.mOldFoo.MirroredElemHasDefaults <:< Tuple] // but does inherit type member from Mirror trait
+
+      // OldBar: is anon mirror so could implement defaultArgument
+      // but we manually keep behaviour consistent with other mirrors of old case classes
+
+      assert(NewMirrors.mOldBar ne lib.OldBar)
+      assert(!foundDefaultArgument(NewMirrors.mOldBar))
+      summon[NewMirrors.mOldBar.MirroredElemHasDefaults =:= (false, false)] // Ok: should be consistent with above
+
+      assert(OldMirrors.mOldBar ne lib.OldBar)
+      assert(!foundDefaultArgument(OldMirrors.mOldBar))
+      summon[scala.util.NotGiven[OldMirrors.mOldBar.MirroredElemHasDefaults <:< (Boolean, Boolean)]]
+      summon[OldMirrors.mOldBar.MirroredElemHasDefaults <:< Tuple]
+
+    }
+  }
+}

sbt-test/scala3-compat/defaultArgument-mirrors-3.3/build.sbt

@@ -0,0 +1,7 @@
+lazy val lib = project.in(file("lib"))
+  .settings(
+    scalaVersion := "3.3.0"
+  )
+
+lazy val app = project.in(file("app"))
+  .dependsOn(lib)

sbt-test/scala3-compat/defaultArgument-mirrors-3.3/lib/Foo.scala

@@ -0,0 +1,13 @@
+package lib
+
+import deriving.Mirror
+
+case class OldFoo(x: Int = 1, y: Int)
+
+case class OldBar(x: Int = 1, y: Int)
+case object OldBar
+
+object OldMirrors {
+  val mOldFoo = summon[Mirror.ProductOf[OldFoo]]
+  val mOldBar = summon[Mirror.ProductOf[OldBar]]
+}

sbt-test/scala3-compat/defaultArgument-mirrors-3.3/project/DottyInjectedPlugin.scala

@@ -0,0 +1,11 @@
+import sbt._
+import Keys._
+
+object DottyInjectedPlugin extends AutoPlugin {
+  override def requires = plugins.JvmPlugin
+  override def trigger = allRequirements
+
+  override val projectSettings = Seq(
+    scalaVersion := sys.props("plugin.scalaVersion")
+  )
+}

sbt-test/scala3-compat/defaultArgument-mirrors-3.3/test

@@ -0,0 +1 @@
+> app/run