diff --git a/compiler/src/dotty/tools/dotc/ast/Desugar.scala b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
index 5fd0ff39d366..dc891b235135 100644
--- a/compiler/src/dotty/tools/dotc/ast/Desugar.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
@@ -576,7 +576,7 @@ object desugar {
       ensureApplied(nu)
     }
 
-    val copiedAccessFlags = if (ctx.scala2Setting) EmptyFlags else AccessFlags
+    val copiedAccessFlags = if (ctx.scala2CompatSetting) EmptyFlags else AccessFlags
 
     // Methods to add to a case class C[..](p1: T1, ..., pN: Tn)(moreParams)
     //     def _1: T1 = this.p1
diff --git a/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala b/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
index 8b053263ed00..ee57916f28f6 100644
--- a/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
+++ b/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
@@ -44,7 +44,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val pageWidth: Setting[Int] = IntSetting("-pagewidth", "Set page width", 80) withAbbreviation "--page-width"
   val strict: Setting[Boolean] = BooleanSetting("-strict", "Use strict type rules, which means some formerly legal code does not typecheck anymore.") withAbbreviation "--strict"
   val language: Setting[List[String]] = MultiStringSetting("-language", "feature", "Enable one or more language features.") withAbbreviation "--language"
-  val rewrite: Setting[Option[Rewrites]] = OptionSetting[Rewrites]("-rewrite", "When used in conjunction with -language:Scala2 rewrites sources to migrate to new syntax") withAbbreviation "--rewrite"
+  val rewrite: Setting[Option[Rewrites]] = OptionSetting[Rewrites]("-rewrite", "When used in conjunction with -language:Scala2Compat rewrites sources to migrate to new syntax") withAbbreviation "--rewrite"
   val silentWarnings: Setting[Boolean] = BooleanSetting("-nowarn", "Silence all warnings.") withAbbreviation "--no-warnings"
   val fromTasty: Setting[Boolean] = BooleanSetting("-from-tasty", "Compile classes from tasty in classpath. The arguments are used as class names.") withAbbreviation "--from-tasty"
 
diff --git a/compiler/src/dotty/tools/dotc/core/Denotations.scala b/compiler/src/dotty/tools/dotc/core/Denotations.scala
index 4dbaddd70739..e47def78fba1 100644
--- a/compiler/src/dotty/tools/dotc/core/Denotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/Denotations.scala
@@ -486,7 +486,7 @@ object Denotations {
                   // things, starting with the return type of this method.
                   if (preferSym(sym2, sym1)) info2
                   else if (preferSym(sym1, sym2)) info1
-                  else if (pre.widen.classSymbol.is(Scala2x) || ctx.scala2Mode)
+                  else if (pre.widen.classSymbol.is(Scala2x) || ctx.scala2CompatMode)
                     info1 // follow Scala2 linearization -
                   // compare with way merge is performed in SymDenotation#computeMembersNamed
                   else throw new MergeError(ex.sym1, ex.sym2, ex.tp1, ex.tp2, pre)
diff --git a/compiler/src/dotty/tools/dotc/core/PatternTypeConstrainer.scala b/compiler/src/dotty/tools/dotc/core/PatternTypeConstrainer.scala
index 09d8a0f54462..b6f9284d6269 100644
--- a/compiler/src/dotty/tools/dotc/core/PatternTypeConstrainer.scala
+++ b/compiler/src/dotty/tools/dotc/core/PatternTypeConstrainer.scala
@@ -199,7 +199,7 @@ trait PatternTypeConstrainer { self: TypeComparer =>
       }
     }
 
-    val widePt = if (ctx.scala2Mode || refinementIsInvariant(patternTp)) scrutineeTp else widenVariantParams(scrutineeTp)
+    val widePt = if (ctx.scala2CompatMode || refinementIsInvariant(patternTp)) scrutineeTp else widenVariantParams(scrutineeTp)
     val narrowTp = SkolemType(patternTp)
     trace(i"constraining simple pattern type $narrowTp <:< $widePt", gadts, res => s"$res\ngadt = ${ctx.gadt.debugBoundsDescription}") {
       isSubType(narrowTp, widePt)
diff --git a/compiler/src/dotty/tools/dotc/core/StdNames.scala b/compiler/src/dotty/tools/dotc/core/StdNames.scala
index 58fdc137e6bf..2a2448e9abc7 100644
--- a/compiler/src/dotty/tools/dotc/core/StdNames.scala
+++ b/compiler/src/dotty/tools/dotc/core/StdNames.scala
@@ -357,6 +357,7 @@ object StdNames {
     val RootPackage: N          = "RootPackage"
     val RootClass: N            = "RootClass"
     val Scala2: N               = "Scala2"
+    val Scala2Compat: N         = "Scala2Compat"
     val Select: N               = "Select"
     val Shape: N                = "Shape"
     val StringContext: N        = "StringContext"
diff --git a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
index a881b361d553..f7ccf4588a56 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -573,7 +573,7 @@ class TypeComparer(initctx: Context) extends ConstraintHandling[AbsentContext] w
             * am not sure how, since the code is buried so deep in subtyping logic.
             */
             def boundsOK =
-              ctx.scala2Mode ||
+              ctx.scala2CompatMode ||
               tp1.typeParams.corresponds(tp2.typeParams)((tparam1, tparam2) =>
                 isSubType(tparam2.paramInfo.subst(tp2, tp1), tparam1.paramInfo))
             val saved = comparedTypeLambdas
@@ -1730,7 +1730,7 @@ class TypeComparer(initctx: Context) extends ConstraintHandling[AbsentContext] w
   /** The greatest lower bound of a list types */
   final def glb(tps: List[Type]): Type = tps.foldLeft(AnyType: Type)(glb)
 
-  def widenInUnions(implicit ctx: Context): Boolean = ctx.scala2Mode || ctx.erasedTypes
+  def widenInUnions(implicit ctx: Context): Boolean = ctx.scala2CompatMode || ctx.erasedTypes
 
   /** The least upper bound of two types
    *  @param canConstrain  If true, new constraints might be added to simplify the lub.
diff --git a/compiler/src/dotty/tools/dotc/core/TypeOps.scala b/compiler/src/dotty/tools/dotc/core/TypeOps.scala
index f0a710ea8b17..3ece5a75eb83 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeOps.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeOps.scala
@@ -369,7 +369,7 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
      *  type parameter corresponding to the wildcard.
      */
     def skolemizeWildcardArgs(tps: List[Type], app: Type) = app match {
-      case AppliedType(tycon, args) if tycon.typeSymbol.isClass && !scala2Mode =>
+      case AppliedType(tycon, args) if tycon.typeSymbol.isClass && !scala2CompatMode =>
         tps.zipWithConserve(tycon.typeSymbol.typeParams) {
           (tp, tparam) => tp match {
             case _: TypeBounds => app.select(tparam)
@@ -500,25 +500,34 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
   def canAutoTuple: Boolean =
     !featureEnabled(nme.noAutoTupling)
 
-  def scala2Mode: Boolean =
-    featureEnabled(nme.Scala2)
+  def scala2CompatMode: Boolean =
+    featureEnabled(nme.Scala2Compat) || {
+      val scala2 = featureEnabled(nme.Scala2)
+      if scala2 then ctx.warning("Use `-language:Scala2Compat` or `import scala.Scala2Compat` instead of `-language:Scala2` or `import scala.Scala2`")
+      scala2
+    }
+
 
   def dynamicsEnabled: Boolean =
     featureEnabled(nme.dynamics)
 
-  def testScala2Mode(msg: => Message, pos: SourcePosition, replace: => Unit = ()): Boolean = {
-    if (scala2Mode) {
+  def testScala2CompatMode(msg: => Message, pos: SourcePosition, replace: => Unit = ()): Boolean = {
+    if (scala2CompatMode) {
       migrationWarning(msg, pos)
       replace
     }
-    scala2Mode
+    scala2CompatMode
   }
 
-  /** Is option -language:Scala2 set?
+  /** Is option -language:Scala2Compat set?
    *  This test is used when we are too early in the pipeline to consider imports.
    */
-  def scala2Setting: Boolean =
-    ctx.settings.language.value.contains(nme.Scala2.toString)
+  def scala2CompatSetting: Boolean =
+    ctx.settings.language.value.contains(nme.Scala2Compat.toString) || {
+      val scala2 = ctx.settings.language.value.contains(nme.Scala2.toString)
+      if scala2 then ctx.warning("Use -language:Scala2Compat instead of -language:Scala2")
+      scala2
+    }
 
   /** Refine child based on parent
    *
diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
index 30c874c54225..3309db3e81c8 100644
--- a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -361,7 +361,7 @@ object Parsers {
             accept(SEMI)
         }
 
-    /** Under -language:Scala2 or -old-syntax, flag
+    /** Under -language:Scala2Compat or -old-syntax, flag
      *
      *    extends p1 with       new p1 with      t1 with
      *            p2                p2           t2
@@ -369,7 +369,7 @@ object Parsers {
      *  as a migration warning or error since that means something else under significant indentation.
      */
     def checkNotWithAtEOL(): Unit =
-      if (in.isScala2Mode || in.oldSyntax) && in.isAfterLineEnd then
+      if (in.isScala2CompatMode || in.oldSyntax) && in.isAfterLineEnd then
         in.errorOrMigrationWarning("`with` cannot be followed by new line, place at beginning of next line instead")
 
     def rewriteNotice(additionalOption: String = "") = {
@@ -446,7 +446,7 @@ object Parsers {
         ts.map(convertToParam(_))
       case t: Typed =>
         in.errorOrMigrationWarning(
-          em"parentheses are required around the parameter of a lambda${rewriteNotice("-language:Scala2")}",
+          em"parentheses are required around the parameter of a lambda${rewriteNotice("-language:Scala2Compat")}",
           t.span)
         patch(source, t.span.startPos, "(")
         patch(source, t.span.endPos, ")")
@@ -1180,7 +1180,7 @@ object Parsers {
             in.errorOrMigrationWarning(em"""symbol literal '${in.name} is no longer supported,
                                            |use a string literal "${in.name}" or an application Symbol("${in.name}") instead,
                                            |or enclose in braces '{${in.name}} if you want a quoted expression.""")
-            if (in.isScala2Mode) {
+            if (in.isScala2CompatMode) {
               patch(source, Span(in.offset, in.offset + 1), "Symbol(\"")
               patch(source, Span(in.charOffset - 1), "\")")
             }
@@ -1681,7 +1681,7 @@ object Parsers {
      *  the initially parsed (...) region?
      */
     def toBeContinued(altToken: Token): Boolean =
-      if in.token == altToken || in.isNewLine || in.isScala2Mode then
+      if in.token == altToken || in.isNewLine || in.isScala2CompatMode then
         false // a newline token means the expression is finished
       else if !in.canStartStatTokens.contains(in.token)
               || in.isLeadingInfixOperator(inConditional = true)
@@ -1803,7 +1803,7 @@ object Parsers {
         in.errorOrMigrationWarning(
           i"""`do <body> while <cond>' is no longer supported,
              |use `while ({<body> ; <cond>}) ()' instead.
-             |${rewriteNotice("-language:Scala2")}
+             |${rewriteNotice("-language:Scala2Compat")}
            """)
         val start = in.skipToken()
         atSpan(start) {
@@ -1812,7 +1812,7 @@ object Parsers {
           val whileStart = in.offset
           accept(WHILE)
           val cond = expr()
-          if (in.isScala2Mode) {
+          if (in.isScala2CompatMode) {
             patch(source, Span(start, start + 2), "while ({")
             patch(source, Span(whileStart, whileStart + 5), ";")
             cond match {
@@ -2002,7 +2002,7 @@ object Parsers {
               in.errorOrMigrationWarning(s"This syntax is no longer supported; parameter needs to be enclosed in (...)")
             in.nextToken()
             val t = infixType()
-            if (false && in.isScala2Mode) {
+            if (false && in.isScala2CompatMode) {
               patch(source, Span(start), "(")
               patch(source, Span(in.lastOffset), ")")
             }
@@ -3106,7 +3106,7 @@ object Parsers {
         val toInsert =
           if (in.token == LBRACE) s"$resultTypeStr ="
           else ": Unit "  // trailing space ensures that `def f()def g()` works.
-        in.testScala2Mode(s"Procedure syntax no longer supported; `$toInsert' should be inserted here") && {
+        in.testScala2CompatMode(s"Procedure syntax no longer supported; `$toInsert' should be inserted here") && {
           patch(source, Span(in.lastOffset), toInsert)
           true
         }
@@ -3120,7 +3120,7 @@ object Parsers {
             case EOF        => incompleteInputError(AuxConstructorNeedsNonImplicitParameter())
             case _          => syntaxError(AuxConstructorNeedsNonImplicitParameter(), nameStart)
           }
-        if (in.isScala2Mode) newLineOptWhenFollowedBy(LBRACE)
+        if (in.isScala2CompatMode) newLineOptWhenFollowedBy(LBRACE)
         val rhs = {
           if (!(in.token == LBRACE && scala2ProcedureSyntax(""))) accept(EQUALS)
           atSpan(in.offset) { subPart(constrExpr) }
@@ -3159,7 +3159,7 @@ object Parsers {
             TypeBoundsTree(EmptyTree, toplevelTyp())
           else typedOpt()
         }
-        if (in.isScala2Mode) newLineOptWhenFollowedBy(LBRACE)
+        if (in.isScala2CompatMode) newLineOptWhenFollowedBy(LBRACE)
         val rhs =
           if (in.token == EQUALS)
             indentRegion(name) {
diff --git a/compiler/src/dotty/tools/dotc/parsing/Scanners.scala b/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
index 24e334d7ffeb..7b9f2e8565dd 100644
--- a/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
+++ b/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
@@ -142,7 +142,7 @@ object Scanners {
     /** A switch whether operators at the start of lines can be infix operators */
     private[Scanners] var allowLeadingInfixOperators = true
 
-    val isScala2Mode: Boolean = ctx.scala2Setting
+    val isScala2CompatMode: Boolean = ctx.scala2CompatSetting
 
     val rewrite = ctx.settings.rewrite.value.isDefined
     val oldSyntax = ctx.settings.oldSyntax.value
@@ -154,7 +154,7 @@ object Scanners {
     val noindentSyntax =
       ctx.settings.noindent.value
       || ctx.settings.oldSyntax.value
-      || isScala2Mode
+      || isScala2CompatMode
     val indentSyntax =
       (if (Config.defaultIndent) !noindentSyntax else ctx.settings.indent.value)
       || rewriteNoIndent
@@ -199,12 +199,12 @@ object Scanners {
     private val commentBuf = new mutable.StringBuilder
 
     private def handleMigration(keyword: Token): Token =
-      if (!isScala2Mode) keyword
+      if (!isScala2CompatMode) keyword
       else if (scala3keywords.contains(keyword)) treatAsIdent()
       else keyword
 
     private def treatAsIdent() = {
-      testScala2Mode(i"$name is now a keyword, write `$name` instead of $name to keep it as an identifier")
+      testScala2CompatMode(i"$name is now a keyword, write `$name` instead of $name to keep it as an identifier")
       patch(source, Span(offset), "`")
       patch(source, Span(offset + name.length), "`")
       IDENTIFIER
@@ -232,14 +232,14 @@ object Scanners {
 // Scala 2 compatibility
 
     /** Cannot use ctx.featureEnabled because accessing the context would force too much */
-    def testScala2Mode(msg: String, span: Span = Span(offset)): Boolean = {
-      if (isScala2Mode) ctx.migrationWarning(msg, source.atSpan(span))
-      isScala2Mode
+    def testScala2CompatMode(msg: String, span: Span = Span(offset)): Boolean = {
+      if (isScala2CompatMode) ctx.migrationWarning(msg, source.atSpan(span))
+      isScala2CompatMode
     }
 
     /** A migration warning if in Scala-2 mode, an error otherwise */
     def errorOrMigrationWarning(msg: String, span: Span = Span(offset)): Unit =
-      if (isScala2Mode) ctx.migrationWarning(msg, source.atSpan(span))
+      if (isScala2CompatMode) ctx.migrationWarning(msg, source.atSpan(span))
       else ctx.error(msg, source.atSpan(span))
 
 // Get next token ------------------------------------------------------------
@@ -371,7 +371,7 @@ object Scanners {
       *   - it does not follow a blank line, and
       *   - it is followed on the same line by at least one ' '
       *     and a token that can start an expression.
-      *  If a leading infix operator is found and -language:Scala2 or -old-syntax is set,
+      *  If a leading infix operator is found and -language:Scala2Compat or -old-syntax is set,
       *  emit a change warning.
       */
     def isLeadingInfixOperator(inConditional: Boolean = true) = (
@@ -388,7 +388,7 @@ object Scanners {
         canStartExprTokens.contains(lookahead.token)
       }
       && {
-        if isScala2Mode || oldSyntax && !rewrite then
+        if isScala2CompatMode || oldSyntax && !rewrite then
           val (what, previous) =
             if inConditional then ("Rest of line", "previous expression in parentheses")
             else ("Line", "expression on the previous line")
@@ -1009,10 +1009,10 @@ object Scanners {
     def isNestedEnd = token == RBRACE || token == OUTDENT
 
     def canStartStatTokens =
-      if isScala2Mode then canStartStatTokens2 else canStartStatTokens3
+      if isScala2CompatMode then canStartStatTokens2 else canStartStatTokens3
 
     def canStartExprTokens =
-      if isScala2Mode then canStartExprTokens2 else canStartExprTokens3
+      if isScala2CompatMode then canStartExprTokens2 else canStartExprTokens3
 
 // Literals -----------------------------------------------------------------
 
diff --git a/compiler/src/dotty/tools/dotc/reporting/Reporter.scala b/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
index 529cbd025a57..a01a9874ad77 100644
--- a/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -144,7 +144,7 @@ trait Reporting { this: Context =>
   }
 
   def errorOrMigrationWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
-    if (ctx.scala2Mode) migrationWarning(msg, pos) else error(msg, pos)
+    if (ctx.scala2CompatMode) migrationWarning(msg, pos) else error(msg, pos)
 
   def restrictionError(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report {
diff --git a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index efa1e95b8106..287cf5fc73ad 100644
--- a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -1931,7 +1931,7 @@ object messages {
     extends Message(UnapplyInvalidReturnTypeID) {
     val kind = "Type Mismatch"
     val addendum =
-      if (ctx.scala2Mode && unapplyName == nme.unapplySeq)
+      if (ctx.scala2CompatMode && unapplyName == nme.unapplySeq)
         "\nYou might want to try to rewrite the extractor to use `unapply` instead."
       else ""
     val msg = em"""| ${Red(i"$unapplyResult")} is not a valid result type of an $unapplyName method of an ${Magenta("extractor")}.$addendum"""
diff --git a/compiler/src/dotty/tools/dotc/transform/NonLocalReturns.scala b/compiler/src/dotty/tools/dotc/transform/NonLocalReturns.scala
index 289d6b91b501..295ce2b5761e 100644
--- a/compiler/src/dotty/tools/dotc/transform/NonLocalReturns.scala
+++ b/compiler/src/dotty/tools/dotc/transform/NonLocalReturns.scala
@@ -88,7 +88,7 @@ class NonLocalReturns extends MiniPhase {
 
   override def transformReturn(tree: Return)(implicit ctx: Context): Tree =
     if (isNonLocalReturn(tree)) {
-      if (!ctx.scala2Mode)
+      if (!ctx.scala2CompatMode)
         ctx.strictWarning("Non local returns are deprecated; use scala.util.control.NonLocalReturns instead", tree.sourcePos)
       nonLocalReturnThrow(tree.expr, tree.from.symbol).withSpan(tree.span)
     }
diff --git a/compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala b/compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala
index af30cdfa7883..a2fcd6295143 100644
--- a/compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala
+++ b/compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala
@@ -167,7 +167,7 @@ object ErrorReporting {
     }
 
     def rewriteNotice: String =
-      if (ctx.scala2Mode) "\nThis patch can be inserted automatically under -rewrite."
+      if (ctx.scala2CompatMode) "\nThis patch can be inserted automatically under -rewrite."
       else ""
   }
 
diff --git a/compiler/src/dotty/tools/dotc/typer/Implicits.scala b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
index 7a41dcd5d352..4e903d519af8 100644
--- a/compiler/src/dotty/tools/dotc/typer/Implicits.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
@@ -141,9 +141,9 @@ object Implicits {
               // The reason for leaving out `Predef_conforms` is that we know it adds
               // nothing since it only relates subtype with supertype.
               //
-              // We keep the old behavior under -language:Scala2.
+              // We keep the old behavior under -language:Scala2Compat.
               val isFunctionInS2 =
-                ctx.scala2Mode && tpw.derivesFrom(defn.FunctionClass(1)) && ref.symbol != defn.Predef_conforms
+                ctx.scala2CompatMode && tpw.derivesFrom(defn.FunctionClass(1)) && ref.symbol != defn.Predef_conforms
               val isImplicitConversion = tpw.derivesFrom(defn.ConversionClass)
               // An implementation of <:< counts as a view
               val isConforms = tpw.derivesFrom(defn.SubTypeClass)
@@ -265,7 +265,7 @@ object Implicits {
      */
     override val level: Int =
       if (outerImplicits == null) 1
-      else if (ctx.scala2Mode ||
+      else if (ctx.scala2CompatMode ||
                (ctx.owner eq outerImplicits.ctx.owner) &&
                (ctx.scope eq outerImplicits.ctx.scope) &&
                !refs.head.implicitName.is(LazyImplicitName)) outerImplicits.level
@@ -567,7 +567,7 @@ trait ImplicitRunInfo {
             addPath(pre.cls.sourceModule.termRef)
           case pre: TermRef =>
             if (pre.symbol.is(Package)) {
-              if (ctx.scala2Mode) {
+              if (ctx.scala2CompatMode) {
                 addCompanion(pre, pre.member(nme.PACKAGE).symbol)
                 addPath(pre.prefix)
               }
@@ -1323,7 +1323,7 @@ trait Implicits { self: Typer =>
           case result: SearchFailure if result.isAmbiguous =>
             val deepPt = pt.deepenProto
             if (deepPt ne pt) inferImplicit(deepPt, argument, span)
-            else if (ctx.scala2Mode && !ctx.mode.is(Mode.OldOverloadingResolution))
+            else if (ctx.scala2CompatMode && !ctx.mode.is(Mode.OldOverloadingResolution))
               inferImplicit(pt, argument, span)(ctx.addMode(Mode.OldOverloadingResolution)) match {
                 case altResult: SearchSuccess =>
                   ctx.migrationWarning(
@@ -1502,7 +1502,7 @@ trait Implicits { self: Typer =>
             negateIfNot(tryImplicit(cand, contextual)) match {
               case fail: SearchFailure =>
                 if (fail.isAmbiguous)
-                  if (ctx.scala2Mode) {
+                  if (ctx.scala2CompatMode) {
                     val result = rank(remaining, found, NoMatchingImplicitsFailure :: rfailures)
                     if (result.isSuccess)
                       warnAmbiguousNegation(fail.reason.asInstanceOf[AmbiguousImplicits])
diff --git a/compiler/src/dotty/tools/dotc/typer/Namer.scala b/compiler/src/dotty/tools/dotc/typer/Namer.scala
index 3d8583b78c6e..78753064c2a7 100644
--- a/compiler/src/dotty/tools/dotc/typer/Namer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Namer.scala
@@ -1151,7 +1151,7 @@ class Namer { typer: Typer =>
               traitReq = parent ne parents.head, stablePrefixReq = true)
           if (pt.derivesFrom(cls)) {
             val addendum = parent match {
-              case Select(qual: Super, _) if ctx.scala2Mode =>
+              case Select(qual: Super, _) if ctx.scala2CompatMode =>
                 "\n(Note that inheriting a class of the same name is no longer allowed)"
               case _ => ""
             }
diff --git a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
index 3de2dee72abe..57bd34f2f298 100644
--- a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -280,7 +280,7 @@ object RefChecks {
             member.name.is(DefaultGetterName) || // default getters are not checked for compatibility
             memberTp.overrides(otherTp,
                 member.matchNullaryLoosely || other.matchNullaryLoosely ||
-                ctx.testScala2Mode(overrideErrorMsg("no longer has compatible type"),
+                ctx.testScala2CompatMode(overrideErrorMsg("no longer has compatible type"),
                    (if (member.owner == clazz) member else clazz).sourcePos))
         catch {
           case ex: MissingType =>
@@ -351,7 +351,7 @@ object RefChecks {
         // Also excluded under Scala2 mode are overrides of default methods of Java traits.
         if (autoOverride(member) ||
             other.owner.isAllOf(JavaInterface) &&
-            ctx.testScala2Mode("`override' modifier required when a Java 8 default method is re-implemented", member.sourcePos))
+            ctx.testScala2CompatMode("`override' modifier required when a Java 8 default method is re-implemented", member.sourcePos))
           member.setFlag(Override)
         else if (member.isType && self.memberInfo(member) =:= self.memberInfo(other))
           () // OK, don't complain about type aliases which are equal
@@ -383,7 +383,7 @@ object RefChecks {
       else if (member.is(ModuleVal) && !other.isRealMethod && !other.isOneOf(Deferred | Lazy))
         overrideError("may not override a concrete non-lazy value")
       else if (member.is(Lazy, butNot = Module) && !other.isRealMethod && !other.is(Lazy) &&
-                 !ctx.testScala2Mode(overrideErrorMsg("may not override a non-lazy value"), member.sourcePos))
+                 !ctx.testScala2CompatMode(overrideErrorMsg("may not override a non-lazy value"), member.sourcePos))
         overrideError("may not override a non-lazy value")
       else if (other.is(Lazy) && !other.isRealMethod && !member.is(Lazy))
         overrideError("must be declared lazy to override a lazy value")
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 505da8883248..f7a1d3726566 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -301,7 +301,7 @@ class Typer extends Namer
               if (!curOwner.is(Package) || isDefinedInCurrentUnit(defDenot))
                 result = checkNewOrShadowed(found, Definition) // no need to go further out, we found highest prec entry
               else {
-                if (ctx.scala2Mode && !foundUnderScala2.exists)
+                if (ctx.scala2CompatMode && !foundUnderScala2.exists)
                   foundUnderScala2 = checkNewOrShadowed(found, Definition, scala2pkg = true)
                 if (defDenot.symbol.is(Package))
                   result = checkNewOrShadowed(previous orElse found, PackageClause)
@@ -382,8 +382,8 @@ class Typer extends Namer
         if (foundUnderScala2.exists && !(foundUnderScala2 =:= found)) {
           ctx.migrationWarning(
             ex"""Name resolution will change.
-              | currently selected                     : $foundUnderScala2
-              | in the future, without -language:Scala2: $found""", tree.sourcePos)
+              | currently selected                           : $foundUnderScala2
+              | in the future, without -language:Scala2Compat: $found""", tree.sourcePos)
           found = foundUnderScala2
         }
         found
@@ -1909,7 +1909,7 @@ class Typer extends Namer
       case _ =>
         val recovered = typed(qual)(ctx.fresh.setExploreTyperState())
         ctx.errorOrMigrationWarning(OnlyFunctionsCanBeFollowedByUnderscore(recovered.tpe.widen), tree.sourcePos)
-        if (ctx.scala2Mode) {
+        if (ctx.scala2CompatMode) {
           // Under -rewrite, patch `x _` to `(() => x)`
           patch(Span(tree.span.start), "(() => ")
           patch(Span(qual.span.end, tree.span.end), ")")
@@ -1930,7 +1930,7 @@ class Typer extends Namer
         else s"use `$prefix<function>$suffix` instead"
       ctx.errorOrMigrationWarning(i"""The syntax `<function> _` is no longer supported;
                                      |you can $remedy""", tree.sourcePos)
-      if (ctx.scala2Mode) {
+      if (ctx.scala2CompatMode) {
         patch(Span(tree.span.start), prefix)
         patch(Span(qual.span.end, tree.span.end), suffix)
       }
@@ -2681,7 +2681,7 @@ class Typer extends Namer
       def isAutoApplied(sym: Symbol): Boolean =
         sym.isConstructor ||
         sym.matchNullaryLoosely ||
-        ctx.testScala2Mode(MissingEmptyArgumentList(sym), tree.sourcePos,
+        ctx.testScala2CompatMode(MissingEmptyArgumentList(sym), tree.sourcePos,
             patch(tree.span.endPos, "()"))
 
       // Reasons NOT to eta expand:
diff --git a/compiler/src/dotty/tools/dotc/typer/VarianceChecker.scala b/compiler/src/dotty/tools/dotc/typer/VarianceChecker.scala
index b85e65ba889a..96cef1948994 100644
--- a/compiler/src/dotty/tools/dotc/typer/VarianceChecker.scala
+++ b/compiler/src/dotty/tools/dotc/typer/VarianceChecker.scala
@@ -173,7 +173,7 @@ class VarianceChecker()(implicit ctx: Context) {
     def checkVariance(sym: Symbol, pos: SourcePosition) = Validator.validateDefinition(sym) match {
       case Some(VarianceError(tvar, required)) =>
         def msg = i"${varianceString(tvar.flags)} $tvar occurs in ${varianceString(required)} position in type ${sym.info} of $sym"
-        if (ctx.scala2Mode &&
+        if (ctx.scala2CompatMode &&
             (sym.owner.isConstructor || sym.ownersIterator.exists(_.isAllOf(ProtectedLocal))))
           ctx.migrationWarning(
             s"According to new variance rules, this is no longer accepted; need to annotate with @uncheckedVariance:\n$msg",
diff --git a/compiler/test/dotty/tools/dotc/CompilationTests.scala b/compiler/test/dotty/tools/dotc/CompilationTests.scala
index 78915d3ce2f8..674a2c2feb15 100644
--- a/compiler/test/dotty/tools/dotc/CompilationTests.scala
+++ b/compiler/test/dotty/tools/dotc/CompilationTests.scala
@@ -36,7 +36,7 @@ class CompilationTests extends ParallelTesting {
     implicit val testGroup: TestGroup = TestGroup("compilePos")
     aggregateTests(
       compileFile("tests/pos/nullarify.scala", defaultOptions.and("-Ycheck:nullarify")),
-      compileFile("tests/pos-scala2/rewrites.scala", scala2Mode.and("-rewrite")).copyToTarget(),
+      compileFile("tests/pos-scala2/rewrites.scala", scala2CompatMode.and("-rewrite")).copyToTarget(),
       compileFile("tests/pos-special/utf8encoded.scala", explicitUTF8),
       compileFile("tests/pos-special/utf16encoded.scala", explicitUTF16),
       compileFile("tests/pos-special/completeFromSource/Test.scala", defaultOptions.and("-sourcepath", "tests/pos-special")),
@@ -48,7 +48,7 @@ class CompilationTests extends ParallelTesting {
       compileFilesInDir("tests/pos-special/strawman-collections", defaultOptions),
       compileFilesInDir("tests/pos-special/isInstanceOf", allowDeepSubtypes.and("-Xfatal-warnings")),
       compileFilesInDir("tests/new", defaultOptions),
-      compileFilesInDir("tests/pos-scala2", scala2Mode),
+      compileFilesInDir("tests/pos-scala2", scala2CompatMode),
       compileFilesInDir("tests/pos", defaultOptions),
       compileFilesInDir("tests/pos-deep-subtype", allowDeepSubtypes),
       compileFile(
@@ -118,9 +118,9 @@ class CompilationTests extends ParallelTesting {
       compileDir("tests/neg-custom-args/impl-conv", defaultOptions.and("-Xfatal-warnings", "-feature")),
       compileFile("tests/neg-custom-args/implicit-conversions.scala", defaultOptions.and("-Xfatal-warnings", "-feature")),
       compileFile("tests/neg-custom-args/implicit-conversions-old.scala", defaultOptions.and("-Xfatal-warnings", "-feature")),
-      compileFile("tests/neg-custom-args/i3246.scala", scala2Mode),
-      compileFile("tests/neg-custom-args/overrideClass.scala", scala2Mode),
-      compileFile("tests/neg-custom-args/ovlazy.scala", scala2Mode.and("-migration", "-Xfatal-warnings")),
+      compileFile("tests/neg-custom-args/i3246.scala", scala2CompatMode),
+      compileFile("tests/neg-custom-args/overrideClass.scala", scala2CompatMode),
+      compileFile("tests/neg-custom-args/ovlazy.scala", scala2CompatMode.and("-migration", "-Xfatal-warnings")),
       compileFile("tests/neg-custom-args/autoTuplingTest.scala", defaultOptions.and("-language:noAutoTupling")),
       compileFile("tests/neg-custom-args/nopredef.scala", defaultOptions.and("-Yno-predef")),
       compileFile("tests/neg-custom-args/noimports.scala", defaultOptions.and("-Yno-imports")),
diff --git a/compiler/test/dotty/tools/vulpix/TestConfiguration.scala b/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
index 67f678be55eb..db121cf00932 100644
--- a/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
+++ b/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
@@ -63,7 +63,7 @@ object TestConfiguration {
   )
   val picklingWithCompilerOptions =
     picklingOptions.withClasspath(withCompilerClasspath).withRunClasspath(withCompilerClasspath)
-  val scala2Mode = defaultOptions and "-language:Scala2"
+  val scala2CompatMode = defaultOptions and "-language:Scala2Compat"
   val explicitUTF8 = defaultOptions and ("-encoding", "UTF8")
   val explicitUTF16 = defaultOptions and ("-encoding", "UTF16")
 }
diff --git a/doc-tool/test/dotty/tools/dottydoc/GenDocs.scala b/doc-tool/test/dotty/tools/dottydoc/GenDocs.scala
index 6eb1f53eec74..26a773be00ef 100644
--- a/doc-tool/test/dotty/tools/dottydoc/GenDocs.scala
+++ b/doc-tool/test/dotty/tools/dottydoc/GenDocs.scala
@@ -22,7 +22,7 @@ trait LocalResources extends DocDriver {
   def withClasspath(files: Array[String]) =
     "-siteroot" +: "../docs" +:
     "-project" +: "Dotty" +:
-    "-language:Scala2" +:
+    "-language:Scala2Compat" +:
     "-classpath" +:
     TestConfiguration.basicClasspath +:
     files
diff --git a/docs/blog/_posts/2016-02-17-scaling-dot-soundness.md b/docs/blog/_posts/2016-02-17-scaling-dot-soundness.md
index 667e0cfe8d82..0be2eb54c111 100644
--- a/docs/blog/_posts/2016-02-17-scaling-dot-soundness.md
+++ b/docs/blog/_posts/2016-02-17-scaling-dot-soundness.md
@@ -144,7 +144,7 @@ arithmetic.
 To ease the transition, we will continue for a while to allow unrestricted type
 projections under a flag, even though they are potentially
 unsound. In the current Dotty compiler, that flag is a language import
-`-language:Scala2`, but it could be something different for other
+`-language:Scala2Compat`, but it could be something different for other
 compilers, e.g. `-unsafe`.  Maybe we can find rules that are less
 restrictive than the ones we have now, and are still sound.  But one
 aspect should be non-negotiable: Any fundamental deviations from the
diff --git a/docs/docs/reference/changed-features/vararg-patterns.md b/docs/docs/reference/changed-features/vararg-patterns.md
index 0b5751def420..77123d8e6f5e 100644
--- a/docs/docs/reference/changed-features/vararg-patterns.md
+++ b/docs/docs/reference/changed-features/vararg-patterns.md
@@ -36,5 +36,5 @@ The change to the grammar is:
 
 ## Compatibility considerations
 
-Under the `-language:Scala2` option, Dotty will accept both the old and the new syntax.
+Under the `-language:Scala2Compat` option, Dotty will accept both the old and the new syntax.
 A migration warning will be emitted when the old syntax is encountered.
diff --git a/docs/docs/reference/dropped-features/auto-apply.md b/docs/docs/reference/dropped-features/auto-apply.md
index 95f8c4d8a6b5..a63e7b5b24aa 100644
--- a/docs/docs/reference/dropped-features/auto-apply.md
+++ b/docs/docs/reference/dropped-features/auto-apply.md
@@ -75,7 +75,7 @@ requirement.
 ### Migrating code
 
 Existing Scala code with inconsistent parameters can still be compiled
-in Dotty under `-language:Scala2`. When paired with the `-rewrite`
+in Dotty under `-language:Scala2Compat`. When paired with the `-rewrite`
 option, the code will be automatically rewritten to conform to Dotty's
 stricter checking.
 
diff --git a/docs/docs/reference/dropped-features/procedure-syntax.md b/docs/docs/reference/dropped-features/procedure-syntax.md
index ab4afeb177fe..812db607732c 100644
--- a/docs/docs/reference/dropped-features/procedure-syntax.md
+++ b/docs/docs/reference/dropped-features/procedure-syntax.md
@@ -12,7 +12,7 @@ has been dropped. You need to write one of the following instead:
 def f() = { ... }
 def f(): Unit = { ... }
 ```
-Dotty will accept the old syntax under the `-language:Scala2` option.
+Dotty will accept the old syntax under the `-language:Scala2Compat` option.
 If the `-migration` option is set, it can even rewrite old syntax to new.
 The [ScalaFix](https://scalacenter.github.io/scalafix/) tool also
 can rewrite procedure syntax to make it Dotty-compatible.
diff --git a/docs/docs/reference/features-classification.md b/docs/docs/reference/features-classification.md
index cb669cfa0c50..b05c44fd48a0 100644
--- a/docs/docs/reference/features-classification.md
+++ b/docs/docs/reference/features-classification.md
@@ -77,7 +77,7 @@ These constructs are restricted to make the language safer.
  - [@infix and @alpha](https://github.com/lampepfl/dotty/pull/5975)
  make method application syntax uniform across code bases and require alphanumeric aliases for all symbolic names (proposed, not implemented).
 
-Unrestricted implicit conversions continue to be available in Scala 3.0, but will be deprecated and removed later. Unrestricted versions of the other constructs in the list above are available only under `-language:Scala2`.
+Unrestricted implicit conversions continue to be available in Scala 3.0, but will be deprecated and removed later. Unrestricted versions of the other constructs in the list above are available only under `-language:Scala2Compat`.
 
 **Status: now or never**
 
@@ -108,7 +108,7 @@ The date when these constructs are dropped varies. The current status is:
 
  - Not implemented at all:
    - DelayedInit, existential types, weak conformance.
- - Supported under `-language:Scala2`:
+ - Supported under `-language:Scala2Compat`:
    - procedure syntax, class shadowing, symbol literals, auto application, auto tupling in a restricted form.
  - Supported in 3.0, to be deprecated and phased out later:
    - XML literals, compound types.
@@ -133,7 +133,7 @@ These constructs have undergone changes to make them more regular and useful.
  - [Eta expansion](changed-features/eta-expansion.md) is now performed universally also in the absence of an expected type. The postfix `_` operator is thus made redundant. It will be deprecated and dropped after Scala 3.0.
  - [Implicit Resolution](changed-features/implicit-resolution.md): The implicit resolution rules have been cleaned up to make them more useful and less surprising. Implicit scope is restricted to no longer include package prefixes.
 
-Most aspects of old-style implicit resolution are still available under `-language:Scala2`. The other changes in this list are applied unconditionally.
+Most aspects of old-style implicit resolution are still available under `-language:Scala2Compat`. The other changes in this list are applied unconditionally.
 
 **Status: strongly advisable**
 
diff --git a/docs/docs/reference/other-new-features/indentation.md b/docs/docs/reference/other-new-features/indentation.md
index 054176d21428..0d89f5bd1ec3 100644
--- a/docs/docs/reference/other-new-features/indentation.md
+++ b/docs/docs/reference/other-new-features/indentation.md
@@ -175,7 +175,7 @@ end IndentWidth
 
 ### Settings and Rewrites
 
-Significant indentation is enabled by default. It can be turned off by giving any of the options `-noindent`, `old-syntax` and `language:Scala2`. If indentation is turned off, it is nevertheless checked that indentation conforms to the logical program structure as defined by braces. If that is not the case, the compiler issues an error (or, in the case of `-language:Scala2`, a migration warning).
+Significant indentation is enabled by default. It can be turned off by giving any of the options `-noindent`, `old-syntax` and `language:Scala2`. If indentation is turned off, it is nevertheless checked that indentation conforms to the logical program structure as defined by braces. If that is not the case, the compiler issues an error (or, in the case of `-language:Scala2Compat`, a migration warning).
 
 The Dotty compiler can rewrite source code to indented code and back.
 When invoked with options `-rewrite -indent` it will rewrite braces to
diff --git a/docs/docs/reference/overview.md b/docs/docs/reference/overview.md
index f699d54a323d..1165d878dc7b 100644
--- a/docs/docs/reference/overview.md
+++ b/docs/docs/reference/overview.md
@@ -63,7 +63,7 @@ These constructs are restricted to make the language safer.
  - [@infix and @alpha](https://github.com/lampepfl/dotty/pull/5975)
  make method application syntax uniform across code bases and require alphanumeric aliases for all symbolic names (proposed, not implemented).
 
-Unrestricted implicit conversions continue to be available in Scala 3.0, but will be deprecated and removed later. Unrestricted versions of the other constructs in the list above are available only under `-language:Scala2`.
+Unrestricted implicit conversions continue to be available in Scala 3.0, but will be deprecated and removed later. Unrestricted versions of the other constructs in the list above are available only under `-language:Scala2Compat`.
 
 
 ## Dropped Constructs
@@ -85,7 +85,7 @@ The date when these constructs are dropped varies. The current status is:
 
  - Not implemented at all:
    - DelayedInit, existential types, weak conformance.
- - Supported under `-language:Scala2`:
+ - Supported under `-language:Scala2Compat`:
    - procedure syntax, class shadowing, symbol literals, auto application, auto tupling in a restricted form.
  - Supported in 3.0, to be deprecated and phased out later:
    - XML literals, compound types.
@@ -100,7 +100,7 @@ These constructs have undergone changes to make them more regular and useful.
  - [Eta expansion](changed-features/eta-expansion.md) is now performed universally also in the absence of an expected type. The postfix `_` operator is thus made redundant. It will be deprecated and dropped after Scala 3.0.
  - [Implicit Resolution](changed-features/implicit-resolution.md): The implicit resolution rules have been cleaned up to make them more useful and less surprising. Implicit scope is restricted to no longer include package prefixes.
 
-Most aspects of old-style implicit resolution are still available under `-language:Scala2`. The other changes in this list are applied unconditionally.
+Most aspects of old-style implicit resolution are still available under `-language:Scala2Compat`. The other changes in this list are applied unconditionally.
 
 ## New Constructs
 
diff --git a/sbt-dotty/sbt-test/compilerReporter/simple/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/compilerReporter/simple/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/compilerReporter/simple/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/compilerReporter/simple/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/discovery/test-discovery/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/discovery/test-discovery/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/discovery/test-discovery/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/discovery/test-discovery/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/abstract-override/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/abstract-override/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/abstract-override/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/abstract-override/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/abstract-type-override/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/abstract-type-override/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/abstract-type-override/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/abstract-type-override/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/abstract-type/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/abstract-type/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/abstract-type/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/abstract-type/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/added/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/added/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/added/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/added/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/anon-class-java-depends-on-scala/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/anon-class-java-depends-on-scala/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/anon-class-java-depends-on-scala/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/anon-class-java-depends-on-scala/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/anon-java-scala-class/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/anon-java-scala-class/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/anon-java-scala-class/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/anon-java-scala-class/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/as-seen-from-a/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/as-seen-from-a/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/as-seen-from-a/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/as-seen-from-a/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/as-seen-from-b/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/as-seen-from-b/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/as-seen-from-b/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/as-seen-from-b/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/backtick-quoted-names/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/backtick-quoted-names/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/backtick-quoted-names/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/backtick-quoted-names/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/binary/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/binary/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/binary/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/binary/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/by-name/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/by-name/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/by-name/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/by-name/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/canon/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/canon/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/canon/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/canon/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/changedTypeOfChildOfSealed/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/changedTypeOfChildOfSealed/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/changedTypeOfChildOfSealed/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/changedTypeOfChildOfSealed/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/check-classes/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/check-classes/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/check-classes/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/check-classes/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/check-dependencies/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/check-dependencies/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/check-dependencies/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/check-dependencies/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/check-products/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/check-products/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/check-products/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/check-products/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/check-recompilations/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/check-recompilations/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/check-recompilations/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/check-recompilations/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/class-based-inheritance/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/class-based-inheritance/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/class-based-inheritance/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/class-based-inheritance/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/class-based-memberRef/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/class-based-memberRef/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/class-based-memberRef/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/class-based-memberRef/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/compactify/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/compactify/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/compactify/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/compactify/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/constants/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/constants/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/constants/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/constants/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/constructors-unrelated/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/constructors-unrelated/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/constructors-unrelated/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/constructors-unrelated/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/continuations/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/continuations/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/continuations/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/continuations/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/cross-source/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/cross-source/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/cross-source/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/cross-source/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/default-params/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/default-params/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/default-params/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/default-params/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/dup-class/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/dup-class/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/dup-class/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/dup-class/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/empty-a/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/empty-a/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/empty-a/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/empty-a/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/empty-modified-names/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/empty-modified-names/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/empty-modified-names/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/empty-modified-names/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/empty-package/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/empty-package/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/empty-package/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/empty-package/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/erasure/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/erasure/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/erasure/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/erasure/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/expanded-type-projection/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/expanded-type-projection/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/expanded-type-projection/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/expanded-type-projection/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/export-jars/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/export-jars/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/export-jars/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/export-jars/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/false-error/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/false-error/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/false-error/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/false-error/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/fbounded-existentials/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/fbounded-existentials/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/fbounded-existentials/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/fbounded-existentials/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/implicit-params/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/implicit-params/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/implicit-params/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/implicit-params/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/implicit-search-companion-scope/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/implicit-search-companion-scope/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/implicit-search-companion-scope/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/implicit-search-companion-scope/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/implicit-search-higher-kinded/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/implicit-search-higher-kinded/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/implicit-search-higher-kinded/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/implicit-search-higher-kinded/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/implicit-search/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/implicit-search/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/implicit-search/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/implicit-search/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/implicit/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/implicit/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/implicit/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/implicit/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/import-class/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/import-class/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/import-class/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/import-class/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/import-package/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/import-package/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/import-package/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/import-package/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/inherited-deps-java/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/inherited-deps-java/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/inherited-deps-java/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/inherited-deps-java/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/inherited_type_params/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/inherited_type_params/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/inherited_type_params/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/inherited_type_params/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/inner-class-java-depends-on-scala/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/inner-class-java-depends-on-scala/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/inner-class-java-depends-on-scala/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/inner-class-java-depends-on-scala/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/intermediate-error/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/intermediate-error/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/intermediate-error/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/intermediate-error/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-analysis-serialization-error/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-analysis-serialization-error/project/DottyInjectedPlugin.scala
index ce3d46d79921..6de08a769899 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-analysis-serialization-error/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-analysis-serialization-error/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2CompatCompat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-anonymous/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-anonymous/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-anonymous/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-anonymous/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-basic/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-basic/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-basic/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-basic/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-enum/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-enum/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-enum/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-enum/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-generic-workaround/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-generic-workaround/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-generic-workaround/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-generic-workaround/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-inner/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-inner/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-inner/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-inner/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-lambda-typeparams/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-lambda-typeparams/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-lambda-typeparams/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-lambda-typeparams/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-mixed/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-mixed/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-mixed/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-mixed/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-name-with-dollars/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-name-with-dollars/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-name-with-dollars/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-name-with-dollars/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/java-static/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/java-static/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/java-static/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/java-static/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/lazy-val/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/lazy-val/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/lazy-val/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/lazy-val/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/less-inter-inv-java/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/less-inter-inv-java/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/less-inter-inv-java/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/less-inter-inv-java/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/less-inter-inv/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/less-inter-inv/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/less-inter-inv/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/less-inter-inv/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/linearization/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/linearization/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/linearization/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/linearization/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/local-class-inheritance-from-java/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/local-class-inheritance-from-java/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/local-class-inheritance-from-java/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/local-class-inheritance-from-java/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/local-class-inheritance/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/local-class-inheritance/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/local-class-inheritance/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/local-class-inheritance/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/malformed-class-name-with-dollar/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/malformed-class-name-with-dollar/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/malformed-class-name-with-dollar/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/malformed-class-name-with-dollar/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/malformed-class-name/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/malformed-class-name/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/malformed-class-name/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/malformed-class-name/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/named/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/named/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/named/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/named/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/nested-case-class/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/nested-case-class/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/nested-case-class/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/nested-case-class/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/nested-type-params/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/nested-type-params/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/nested-type-params/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/nested-type-params/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/new-cyclic/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/new-cyclic/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/new-cyclic/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/new-cyclic/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/new-pkg-dep/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/new-pkg-dep/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/new-pkg-dep/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/new-pkg-dep/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/override/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/override/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/override/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/override/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/package-object-implicit/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/package-object-implicit/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/package-object-implicit/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/package-object-implicit/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/package-object-name/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/package-object-name/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/package-object-name/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/package-object-name/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/package-object-nested-class/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/package-object-nested-class/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/package-object-nested-class/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/package-object-nested-class/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/packageobject-and-traits/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/packageobject-and-traits/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/packageobject-and-traits/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/packageobject-and-traits/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/parent-change/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/parent-change/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/parent-change/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/parent-change/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/parent-member-change/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/parent-member-change/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/parent-member-change/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/parent-member-change/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/pkg-private-class/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/pkg-private-class/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/pkg-private-class/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/pkg-private-class/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/pkg-self/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/pkg-self/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/pkg-self/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/pkg-self/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/qualified-access/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/qualified-access/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/qualified-access/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/qualified-access/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/recorded-products/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/recorded-products/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/recorded-products/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/recorded-products/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/relative-source-error/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/relative-source-error/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/relative-source-error/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/relative-source-error/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/remove-test-a/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/remove-test-a/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/remove-test-a/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/remove-test-a/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/remove-test-b/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/remove-test-b/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/remove-test-b/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/remove-test-b/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/repeated-parameters/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/repeated-parameters/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/repeated-parameters/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/repeated-parameters/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/replace-test-a/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/replace-test-a/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/replace-test-a/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/replace-test-a/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/resident-java/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/resident-java/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/resident-java/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/resident-java/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/resident-package-object/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/resident-package-object/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/resident-package-object/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/resident-package-object/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/restore-classes/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/restore-classes/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/restore-classes/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/restore-classes/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/same-file-used-names/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/same-file-used-names/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/same-file-used-names/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/same-file-used-names/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/sealed/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/sealed/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/sealed/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/sealed/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/signature-change/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/signature-change/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/signature-change/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/signature-change/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/specialized/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/specialized/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/specialized/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/specialized/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/stability-change/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/stability-change/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/stability-change/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/stability-change/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/struct-projection/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/struct-projection/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/struct-projection/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/struct-projection/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/struct-usage/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/struct-usage/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/struct-usage/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/struct-usage/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/struct/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/struct/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/struct/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/struct/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/synthetic-companion/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/synthetic-companion/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/synthetic-companion/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/synthetic-companion/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/trait-member-modified/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/trait-member-modified/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/trait-member-modified/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/trait-member-modified/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/trait-private-object/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/trait-private-object/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/trait-private-object/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/trait-private-object/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/trait-private-val/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/trait-private-val/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/trait-private-val/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/trait-private-val/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/trait-private-var/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/trait-private-var/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/trait-private-var/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/trait-private-var/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/trait-super/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/trait-super/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/trait-super/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/trait-super/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/transitive-a/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/transitive-a/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/transitive-a/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/transitive-a/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/transitive-b/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/transitive-b/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/transitive-b/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/transitive-b/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/transitive-class/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/transitive-class/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/transitive-class/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/transitive-class/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/transitive-inherit-java/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/transitive-inherit-java/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/transitive-inherit-java/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/transitive-inherit-java/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/transitive-inherit/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/transitive-inherit/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/transitive-inherit/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/transitive-inherit/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/transitive-memberRef/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/transitive-memberRef/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/transitive-memberRef/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/transitive-memberRef/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/type-alias/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/type-alias/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/type-alias/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/type-alias/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/type-member-nested-object/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/type-member-nested-object/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/type-member-nested-object/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/type-member-nested-object/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/type-parameter/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/type-parameter/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/type-parameter/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/type-parameter/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/typeargref/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/typeargref/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/typeargref/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/typeargref/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/typeref-only/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/typeref-only/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/typeref-only/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/typeref-only/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/typeref-return/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/typeref-return/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/typeref-return/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/typeref-return/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/types-in-used-names-a/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/types-in-used-names-a/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/types-in-used-names-a/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/types-in-used-names-a/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/types-in-used-names-b/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/types-in-used-names-b/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/types-in-used-names-b/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/types-in-used-names-b/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/unexpanded-names/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/unexpanded-names/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/unexpanded-names/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/unexpanded-names/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/value-class-underlying/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/value-class-underlying/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/value-class-underlying/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/value-class-underlying/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/value-class/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/value-class/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/value-class/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/value-class/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/var/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/var/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/var/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/var/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }
diff --git a/sbt-dotty/sbt-test/source-dependencies/variance/project/DottyInjectedPlugin.scala b/sbt-dotty/sbt-test/source-dependencies/variance/project/DottyInjectedPlugin.scala
index ce3d46d79921..6a77cb33121e 100644
--- a/sbt-dotty/sbt-test/source-dependencies/variance/project/DottyInjectedPlugin.scala
+++ b/sbt-dotty/sbt-test/source-dependencies/variance/project/DottyInjectedPlugin.scala
@@ -7,6 +7,6 @@ object DottyInjectedPlugin extends AutoPlugin {
 
   override val projectSettings = Seq(
     scalaVersion := sys.props("plugin.scalaVersion"),
-    scalacOptions += "-language:Scala2"
+    scalacOptions += "-language:Scala2Compat"
   )
 }