Migrate to scala 3 (#311)

* Prepare for migration - move scala2 code which cannot be migrated to separate directory

* Compile base scala-3 code

* Enable tests for product derivation

* Enable basic tests for collections

* Autoderivation should in the end returns Derived[Diff]

* Convert Derived to value class so it can be inlined

(this is required by inline macro in scala3)

* Migrate ignore and modify macros to scala3

* Fix more of the DiffTest

* Migrate modifyMacro test

* Migrate ObjectMatcherTest

* Migrate DiffModifyIntegrationTest

* Fix docs compilation

* Bring back use of auto-derivation in scala-2 tests

* Fix js build

* Unify return type of `derived` method across scala versions

* Restore auto derivation for scala3

* Migrate useMatcher macro to scala3

* Uncomment "coproduct types with ignored fields" test

* Split derivedDiff into two methods

* Uncomment "set of products" test

* Uncomment rest of DiffModifyIntegrationTest

* Unify tests across scala versions

* Migrate scalatest to scala3

* Enable scala3 for cats module

* Enable scala3 for tagging module

* Enable scala3 for munit

* Add test for non case class instances to core

* Make fallback work on scala3

* Change autoDerive to autoDerived

* Cross compile core for scala3 js

* Cross compile utest for scala3 and scala3 js

* Enable autoDerivation in a way that works on all versions

* Enable scala3 js for cats module

* Enable scala3 js for tagging module

* Enable scala3 js for munit module

* Enable scala3 js for scalatest module

* Run scalafmt across all modules

* Simplify code as there is no need for DerivedLens anymore after switch to be an invariant tc

* Add missing autoDerivation to specs2-test

* Enable scala3 for refined module

* Update diffx supported scala version

* Add note on autoDerived method

.scalafmt.conf

@@ -1,2 +1,8 @@
 version = 3.0.8
 maxColumn = 120
+runner.dialect = scala3
+fileOverride {
+  "glob:**/scala-2/**" {
+    runner.dialect = scala213
+  }
+}

build.sbt

@@ -6,8 +6,9 @@ import com.softwaremill.Publish.{ossPublishSettings, updateDocs}
 
 val scala212 = "2.12.14"
 val scala213 = "2.13.6"
+val scala3 = "3.0.2"
 
-val scalaIdeaVersion = scala212 // the version for which to import sources into intellij
+val scalaIdeaVersion = scala3 // the version for which to import sources into intellij
 
 val scalatestVersion = "3.2.10"
 val specs2Version = "4.13.0"
@@ -51,9 +52,20 @@ lazy val core = (projectMatrix in file("core"))
   .settings(commonSettings)
   .settings(
     name := "diffx-core",
+    libraryDependencies ++= {
+      CrossVersion.partialVersion(scalaVersion.value) match {
+        case Some((3, _)) =>
+          Seq(
+            "com.softwaremill.magnolia1_3" %%% "magnolia" % "1.0.0-M7"
+          )
+        case _ =>
+          Seq(
+            "com.propensive" %%% "magnolia" % "0.17.0",
+            "org.scala-lang" % "scala-reflect" % scalaVersion.value % Provided
+          )
+      }
+    },
     libraryDependencies ++= Seq(
-      "com.propensive" %%% "magnolia" % "0.17.0",
-      "org.scala-lang" % "scala-reflect" % scalaVersion.value,
       "org.scalatest" %%% "scalatest-flatspec" % scalatestVersion % Test,
       "org.scalatest" %%% "scalatest-freespec" % scalatestVersion % Test,
       "org.scalatest" %%% "scalatest-shouldmatchers" % scalatestVersion % Test,
@@ -62,10 +74,10 @@ lazy val core = (projectMatrix in file("core"))
     versionSpecificScalaSources
   )
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
 
 lazy val scalatestMust = (projectMatrix in file("scalatest-must"))
@@ -80,10 +92,10 @@ lazy val scalatestMust = (projectMatrix in file("scalatest-must"))
   )
   .dependsOn(core)
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
 
 lazy val scalatestShould = (projectMatrix in file("scalatest-should"))
@@ -98,10 +110,10 @@ lazy val scalatestShould = (projectMatrix in file("scalatest-should"))
   )
   .dependsOn(core)
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
 
 lazy val scalatestLegacy = (projectMatrix in file("scalatest"))
@@ -116,10 +128,10 @@ lazy val scalatestLegacy = (projectMatrix in file("scalatest"))
   )
   .dependsOn(core)
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
 
 lazy val specs2 = (projectMatrix in file("specs2"))
@@ -149,10 +161,10 @@ lazy val utest = (projectMatrix in file("utest"))
   )
   .dependsOn(core)
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
 
 lazy val munit = (projectMatrix in file("munit"))
@@ -166,10 +178,10 @@ lazy val munit = (projectMatrix in file("munit"))
   )
   .dependsOn(core)
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213),
+    scalaVersions = List(scala212, scala213, scala3),
     settings = commonSettings ++ Seq(scalaJSLinkerConfig ~= { _.withModuleKind(ModuleKind.CommonJSModule) })
   )
 
@@ -185,10 +197,10 @@ lazy val tagging = (projectMatrix in file("tagging"))
   )
   .dependsOn(core)
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
 
 lazy val cats = (projectMatrix in file("cats"))
@@ -203,10 +215,10 @@ lazy val cats = (projectMatrix in file("cats"))
   )
   .dependsOn(core)
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
 
 lazy val refined = (projectMatrix in file("refined"))
@@ -221,12 +233,11 @@ lazy val refined = (projectMatrix in file("refined"))
   )
   .dependsOn(core)
   .jvmPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
   .jsPlatform(
-    scalaVersions = List(scala212, scala213)
+    scalaVersions = List(scala212, scala213, scala3)
   )
-//
 
 lazy val docs = (projectMatrix in file("generated-docs")) // important: it must not be docs/
   .enablePlugins(MdocPlugin)

core/src/main/scala-2/com/softwaremill/diffx/DiffCompanionMacro.scala

@@ -0,0 +1,8 @@
+package com.softwaremill.diffx
+
+import com.softwaremill.diffx.generic.DiffMagnoliaDerivation
+import magnolia.Magnolia
+
+trait DiffCompanionMacro extends DiffMagnoliaDerivation {
+  def derived[T]: Diff[T] = macro Magnolia.gen[T]
+}

core/src/main/scala-2/com/softwaremill/diffx/DiffLensMacro.scala

@@ -0,0 +1,5 @@
+package com.softwaremill.diffx
+
+trait DiffLensMacro[T, U] {
+  def useMatcher[M](matcher: ObjectMatcher[M]): Diff[T] = macro ModifyMacro.withObjectMatcher[T, U, M]
+}

core/src/main/scala-2/com/softwaremill/diffx/DiffMacro.scala

@@ -0,0 +1,6 @@
+package com.softwaremill.diffx
+
+trait DiffMacro[T] {
+  def modify[U](path: T => U): DiffLens[T, U] = macro ModifyMacro.modifyMacro[T, U]
+  def ignore[U](path: T => U)(implicit conf: DiffConfiguration): Diff[T] = macro ModifyMacro.ignoreMacro[T, U]
+}

core/src/main/scala/com/softwaremill/diffx/ModifyMacro.scala → core/src/main/scala-2/com/softwaremill/diffx/ModifyMacro.scala

@@ -8,32 +8,6 @@ import scala.reflect.macros.blackbox
 object ModifyMacro {
   private val ShapeInfo = "Path must have shape: _.field1.field2.each.field3.(...)"
 
-  def derivedModifyMacro[T: c.WeakTypeTag, U: c.WeakTypeTag](
-      c: blackbox.Context
-  )(path: c.Expr[T => U]): c.Tree =
-    applyDerivedModified[T, U](c)(modifiedFromPathMacro(c)(path))
-
-  private def applyDerivedModified[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(
-      path: c.Expr[List[String]]
-  ): c.Tree = {
-    import c.universe._
-    q"""com.softwaremill.diffx.DerivedDiffLens(${c.prefix}.dd.value, $path)"""
-  }
-
-  def derivedIgnoreMacro[T: c.WeakTypeTag, U: c.WeakTypeTag](
-      c: blackbox.Context
-  )(path: c.Expr[T => U])(conf: c.Expr[DiffConfiguration]): c.Tree =
-    applyIgnoredModified[T, U](c)(modifiedFromPathMacro(c)(path), conf)
-
-  private def applyIgnoredModified[T: c.WeakTypeTag, U: c.WeakTypeTag](c: blackbox.Context)(
-      path: c.Expr[List[String]],
-      conf: c.Expr[DiffConfiguration]
-  ): c.Tree = {
-    import c.universe._
-    val lens = applyDerivedModified[T, U](c)(path)
-    q"""$lens.ignore($conf)"""
-  }
-
   def ignoreMacro[T: c.WeakTypeTag, U: c.WeakTypeTag](
       c: blackbox.Context
   )(path: c.Expr[T => U])(conf: c.Expr[DiffConfiguration]): c.Tree =
@@ -56,7 +30,7 @@ object ModifyMacro {
   )(path: c.Expr[List[String]]): c.Tree = {
     import c.universe._
     q"""{
-      com.softwaremill.diffx.DiffLens(${c.prefix}.d, $path)
+      com.softwaremill.diffx.DiffLens(${c.prefix}, $path)
      }"""
   }
 
@@ -115,14 +89,6 @@ object ModifyMacro {
   private[diffx] def modifiedFromPath[T, U](path: T => U): List[String] =
     macro modifiedFromPathMacro[T, U]
 
-  def withObjectMatcherDerived[T: c.WeakTypeTag, U: c.WeakTypeTag, M: c.WeakTypeTag](
-      c: blackbox.Context
-  )(matcher: c.Expr[ObjectMatcher[M]]): c.Tree = {
-    import c.universe._
-    val diff = withObjectMatcher[T, U, M](c)(matcher)
-    q"com.softwaremill.diffx.Derived($diff)"
-  }
-
   def withObjectMatcher[T: c.WeakTypeTag, U: c.WeakTypeTag, M: c.WeakTypeTag](
       c: blackbox.Context
   )(matcher: c.Expr[ObjectMatcher[M]]): c.Tree = {
@@ -141,7 +107,7 @@ object ModifyMacro {
     if (!setRequirements && !iterableRequirements && !mapRequirements) { //  weakTypeOf[U] <:< tq"Iterable[${u.typeArgs.head.termSymbol}]"
       c.abort(c.enclosingPosition, s"Invalid objectMather type $u for given lens($t,$m)")
     }
-    q""" 
+    q"""
        val lens = ${c.prefix}
        lens.outer.modifyMatcherUnsafe(lens.path: _*)($matcher)
     """

core/src/main/scala/com/softwaremill/diffx/generic/DiffMagnoliaDerivation.scala → core/src/main/scala-2/com/softwaremill/diffx/generic/DiffMagnoliaDerivation.scala

@@ -1,19 +1,11 @@
 package com.softwaremill.diffx.generic
 
-import com.softwaremill.diffx.{
-  Diff,
-  DiffContext,
-  DiffResultObject,
-  DiffResultValue,
-  FieldPath,
-  IdenticalValue,
-  nullGuard
-}
+import com.softwaremill.diffx.{Diff, DiffContext, DiffResultObject, DiffResultValue, nullGuard}
 import magnolia._
 
 import scala.collection.immutable.ListMap
 
-trait DiffMagnoliaDerivation extends LowPriority {
+trait DiffMagnoliaDerivation {
   type Typeclass[T] = Diff[T]
 
   def combine[T](ctx: ReadOnlyCaseClass[Typeclass, T]): Diff[T] = { (left: T, right: T, context: DiffContext) =>
@@ -44,15 +36,6 @@ trait DiffMagnoliaDerivation extends LowPriority {
       }
     }
   }
-}
 
-trait LowPriority {
-  def fallback[T]: Diff[T] =
-    (left: T, right: T, context: DiffContext) => {
-      if (left != right) {
-        DiffResultValue(left, right)
-      } else {
-        IdenticalValue(left)
-      }
-    }
+  def fallback[T]: Diff[T] = Diff.useEquals[T]
 }

core/src/main/scala/com/softwaremill/diffx/generic/MagnoliaDerivedMacro.scala → core/src/main/scala-2/com/softwaremill/diffx/generic/MagnoliaDerivedMacro.scala

@@ -2,9 +2,9 @@ package com.softwaremill.diffx.generic
 
 import com.softwaremill.diffx.Derived
 import magnolia.Magnolia
-import scala.language.experimental.macros
 
 object MagnoliaDerivedMacro {
+
   import scala.reflect.macros.whitebox
 
   def derivedGen[T: c.WeakTypeTag](c: whitebox.Context): c.Expr[Derived[T]] = {

core/src/main/scala-3/com/softwaremill/diffx/DiffCompanionMacro.scala

@@ -0,0 +1,8 @@
+package com.softwaremill.diffx
+
+import com.softwaremill.diffx.generic.DiffMagnoliaDerivation
+import com.softwaremill.diffx.generic.auto.DiffAutoDerivationOn
+
+trait DiffCompanionMacro extends DiffMagnoliaDerivation {
+  given fallback[T](using DiffAutoDerivationOn): Derived[Diff[T]] = Derived(Diff.useEquals[T])
+}

core/src/main/scala-3/com/softwaremill/diffx/DiffLensMacro.scala

@@ -0,0 +1,7 @@
+package com.softwaremill.diffx
+
+trait DiffLensMacro[T, U] { outer: DiffLens[T, U] =>
+  inline def useMatcher[M](inline matcher: ObjectMatcher[M]): Diff[T] = ${
+    ModifyMacro.withObjectMatcher[T, U, M]('outer)('matcher)
+  }
+}

core/src/main/scala-3/com/softwaremill/diffx/DiffMacro.scala

@@ -0,0 +1,8 @@
+package com.softwaremill.diffx
+
+trait DiffMacro[T] { outer: Diff[T] =>
+  inline def modify[U](inline path: T => U): DiffLens[T, U] = ${ ModifyMacro.modifyMacro[T, U]('outer)('path) }
+  inline def ignore[U](inline path: T => U)(implicit config: DiffConfiguration): Diff[T] = ${
+    ModifyMacro.ignoreMacro[T, U]('outer)('path, 'config)
+  }
+}