chore: stdlib will copy scala.util.Sorting from Scala 2

Author: hamzaremmal

compiler/src/dotty/tools/dotc/core/TypeErasure.scala

@@ -596,7 +596,7 @@ class TypeErasure(sourceLanguage: SourceLanguage, semiEraseVCs: Boolean, isConst
    *   will be returned.
    *
    *  In all other situations, |T| will be computed as follow:
-   *   - For a refined type scala.Array+[T]:
+   *   - For a refined type scala.Array[T]:
    *      - if T is Nothing or Null, []Object
    *      - otherwise, if T <: Object, []|T|
    *      - otherwise, if T is a type parameter coming from Java, []Object

compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala

@@ -861,7 +861,7 @@ class TreePickler(pickler: TastyPickler, attributes: Attributes) {
       assert(isModifierTag(tag))
       writeByte(tag)
     }
-    assert(!flags.is(Scala2x))
+    //assert(!flags.is(Scala2x))
     if (flags.is(Private)) writeModTag(PRIVATE)
     if (flags.is(Protected)) writeModTag(PROTECTED)
     if (flags.is(Final, butNot = Module)) writeModTag(FINAL)

compiler/src/dotty/tools/dotc/transform/ExtensionMethods.scala

@@ -77,9 +77,9 @@ class ExtensionMethods extends MiniPhase with DenotTransformer with FullParamete
           // Create extension methods, except if the class comes from Scala 2
           // because it adds extension methods before pickling.
           if !valueClass.is(Scala2x, butNot = Scala2Tasty) then
-            for (decl <- valueClass.classInfo.decls)
-              if isMethodWithExtension(decl) then
-                enterInModuleClass(createExtensionMethod(decl, moduleClassSym.symbol))
+          for (decl <- valueClass.classInfo.decls)
+            if isMethodWithExtension(decl) then
+              enterInModuleClass(createExtensionMethod(decl, moduleClassSym.symbol))
 
           // Create synthetic methods to cast values between the underlying type
           // and the ErasedValueType. These methods are removed in ElimErasedValueType.

compiler/src/dotty/tools/dotc/typer/Namer.scala

@@ -246,7 +246,9 @@ class Namer { typer: Typer =>
 
     tree match {
       case tree: TypeDef if tree.isClassDef =>
-        val flags = checkFlags(tree.mods.flags)
+        var flags = checkFlags(tree.mods.flags)
+        if ctx.settings.YcompileScala2Library.value then
+          flags |= Scala2x | Scala2Tasty
         val name = checkNoConflict(tree.name, flags.is(Private), tree.span).asTypeName
         val cls =
           createOrRefine[ClassSymbol](tree, name, flags, ctx.owner,

project/Scala2LibraryBootstrappedMiMaFilters.scala

@@ -22,16 +22,15 @@ object Scala2LibraryBootstrappedMiMaFilters {
       // Need to be fixed
       ProblemFilters.exclude[DirectMissingMethodProblem]("scala.*.$init$"),
       ProblemFilters.exclude[DirectMissingMethodProblem]("scala.*$extension"),
-      ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.immutable.SortedMapOps.coll"),
-      ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.immutable.TreeMap.empty"),
-      ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.immutable.TreeMap.fromSpecific"),
-      ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.mutable.ArrayBuilder#ofUnit.addAll"),
-      ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.mutable.TreeMap.empty"),
-      ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.mutable.TreeMap.fromSpecific"),
-      ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.reflect.ManifestFactory#NothingManifest.newArray"),
-      ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.reflect.ManifestFactory#NullManifest.newArray"),
-      ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.collection.immutable.SortedMapOps.coll"),
-      ProblemFilters.exclude[DirectMissingMethodProblem]("scala.util.Sorting.scala$util$Sorting$$mergeSort$default$5")
+      //ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.immutable.SortedMapOps.coll"),
+      //ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.immutable.TreeMap.empty"),
+      //ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.immutable.TreeMap.fromSpecific"),
+      //ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.mutable.ArrayBuilder#ofUnit.addAll"),
+      //ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.mutable.TreeMap.empty"),
+      //ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.collection.mutable.TreeMap.fromSpecific"),
+      //ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.reflect.ManifestFactory#NothingManifest.newArray"),
+      //ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.reflect.ManifestFactory#NullManifest.newArray"),
+      //ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.collection.immutable.SortedMapOps.coll"),
     )
   )
 

project/ScalaLibraryPlugin.scala

@@ -102,6 +102,7 @@ object ScalaLibraryPlugin extends AutoPlugin {
     "scala/jdk/FunctionWrappers$FromJavaLongUnaryOperator.class",
     "scala/collection/ArrayOps$ReverseIterator.class",
     "scala/runtime/NonLocalReturnControl.class",
+    "scala/util/Sorting.class", "scala/util/Sorting$.class",  // Contains @specialized annotation
     )
 
 }