diff --git a/compiler/src/dotty/tools/dotc/Bench.scala b/compiler/src/dotty/tools/dotc/Bench.scala
index 927b638f77dc..892c683181d8 100644
--- a/compiler/src/dotty/tools/dotc/Bench.scala
+++ b/compiler/src/dotty/tools/dotc/Bench.scala
@@ -4,6 +4,8 @@ package dotc
 import core.Contexts.Context
 import reporting.Reporter
 
+import scala.annotation.internal.sharable
+
 /** A main class for running compiler benchmarks. Can instantiate a given
  *  number of compilers and run each (sequentially) a given number of times
  *  on the same sources.
diff --git a/compiler/src/dotty/tools/dotc/ast/Desugar.scala b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
index 94304f5d90aa..3b27999cad35 100644
--- a/compiler/src/dotty/tools/dotc/ast/Desugar.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
@@ -13,6 +13,8 @@ import collection.mutable.ListBuffer
 import reporting.diagnostic.messages._
 import reporting.trace
 
+import scala.annotation.internal.sharable
+
 object desugar {
   import untpd._
   import DesugarEnums._
diff --git a/compiler/src/dotty/tools/dotc/ast/DesugarEnums.scala b/compiler/src/dotty/tools/dotc/ast/DesugarEnums.scala
index ebb3157a5733..77fe8dd97379 100644
--- a/compiler/src/dotty/tools/dotc/ast/DesugarEnums.scala
+++ b/compiler/src/dotty/tools/dotc/ast/DesugarEnums.scala
@@ -10,6 +10,8 @@ import collection.mutable.ListBuffer
 import util.Property
 import typer.ErrorReporting._
 
+import scala.annotation.internal.sharable
+
 /** Helper methods to desugar enums */
 object DesugarEnums {
   import untpd._
diff --git a/compiler/src/dotty/tools/dotc/ast/Trees.scala b/compiler/src/dotty/tools/dotc/ast/Trees.scala
index 1213661673b2..0f512627a4d4 100644
--- a/compiler/src/dotty/tools/dotc/ast/Trees.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Trees.scala
@@ -14,6 +14,7 @@ import parsing.Tokens.Token
 import printing.Printer
 import util.{Stats, Attachment, Property, DotClass}
 import config.Config
+import annotation.internal.sharable
 import annotation.unchecked.uncheckedVariance
 import language.implicitConversions
 
diff --git a/compiler/src/dotty/tools/dotc/ast/untpd.scala b/compiler/src/dotty/tools/dotc/ast/untpd.scala
index b663a827679c..878d307dcd66 100644
--- a/compiler/src/dotty/tools/dotc/ast/untpd.scala
+++ b/compiler/src/dotty/tools/dotc/ast/untpd.scala
@@ -11,6 +11,8 @@ import language.higherKinds
 import collection.mutable.ListBuffer
 import reflect.ClassTag
 
+import scala.annotation.internal.sharable
+
 object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
 
   // ----- Tree cases that exist in untyped form only ------------------
diff --git a/compiler/src/dotty/tools/dotc/config/CommandLineParser.scala b/compiler/src/dotty/tools/dotc/config/CommandLineParser.scala
index 2298b8b209cb..c8304010e1b1 100644
--- a/compiler/src/dotty/tools/dotc/config/CommandLineParser.scala
+++ b/compiler/src/dotty/tools/dotc/config/CommandLineParser.scala
@@ -2,7 +2,7 @@ package dotty.tools.dotc
 package config
 
 import scala.annotation.tailrec
-import dotty.tools.sharable
+import scala.annotation.internal.sharable
 
 /** A simple (overly so) command line parser.
  *  !!! This needs a thorough test suite to make sure quoting is
diff --git a/compiler/src/dotty/tools/dotc/config/Properties.scala b/compiler/src/dotty/tools/dotc/config/Properties.scala
index efd7274f7a3e..9122272d588e 100644
--- a/compiler/src/dotty/tools/dotc/config/Properties.scala
+++ b/compiler/src/dotty/tools/dotc/config/Properties.scala
@@ -2,6 +2,8 @@ package dotty.tools
 package dotc
 package config
 
+import scala.annotation.internal.sharable
+
 import java.io.{ IOException, PrintWriter }
 import java.util.jar.Attributes.{ Name => AttributeName }
 
diff --git a/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala b/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
index 7fb8b9b79863..313806ef880d 100644
--- a/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
+++ b/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
@@ -94,6 +94,8 @@ class ScalaSettings extends Settings.SettingGroup {
   val YlogClasspath = BooleanSetting("-Ylog-classpath", "Output information about what classpath is being applied.")
   val YdisableFlatCpCaching  = BooleanSetting("-YdisableFlatCpCaching", "Do not cache flat classpath representation of classpath elements from jars across compiler instances.")
 
+  val Yscala2Unpickler = StringSetting("-Yscala2-unpickler", "", "Control where we may get Scala 2 symbols from. This is either \"always\", \"never\", or a classpath.", "always")
+
   val YnoImports = BooleanSetting("-Yno-imports", "Compile without importing scala.*, java.lang.*, or Predef.")
   val YnoInline = BooleanSetting("-Yno-inline", "Suppress inlining.")
   val YnoGenericSig = BooleanSetting("-Yno-generic-signatures", "Suppress generation of generic signatures for Java.")
diff --git a/compiler/src/dotty/tools/dotc/config/ScalaVersion.scala b/compiler/src/dotty/tools/dotc/config/ScalaVersion.scala
index 02ba74af97c0..9bb7431d5384 100644
--- a/compiler/src/dotty/tools/dotc/config/ScalaVersion.scala
+++ b/compiler/src/dotty/tools/dotc/config/ScalaVersion.scala
@@ -3,6 +3,7 @@
 package dotty.tools
 package dotc.config
 
+import scala.annotation.internal.sharable
 import scala.util.{Try, Success, Failure}
 
 /**
diff --git a/compiler/src/dotty/tools/dotc/core/Contexts.scala b/compiler/src/dotty/tools/dotc/core/Contexts.scala
index 18d7ea10e061..cb3272a3cdb3 100644
--- a/compiler/src/dotty/tools/dotc/core/Contexts.scala
+++ b/compiler/src/dotty/tools/dotc/core/Contexts.scala
@@ -29,6 +29,8 @@ import collection.immutable.BitSet
 import printing._
 import config.{JavaPlatform, Platform, ScalaSettings, Settings}
 
+import scala.annotation.internal.sharable
+
 import language.implicitConversions
 import DenotTransformers.DenotTransformer
 import dotty.tools.dotc.profile.Profiler
diff --git a/compiler/src/dotty/tools/dotc/core/NameKinds.scala b/compiler/src/dotty/tools/dotc/core/NameKinds.scala
index 4e1494f28ed8..5920b6b29af0 100644
--- a/compiler/src/dotty/tools/dotc/core/NameKinds.scala
+++ b/compiler/src/dotty/tools/dotc/core/NameKinds.scala
@@ -11,6 +11,8 @@ import Decorators._
 import Contexts.Context
 import collection.mutable
 
+import scala.annotation.internal.sharable
+
 /** Defines possible kinds of NameInfo of a derived name */
 object NameKinds {
 
diff --git a/compiler/src/dotty/tools/dotc/core/Names.scala b/compiler/src/dotty/tools/dotc/core/Names.scala
index 1c2af332f8eb..fc1774cfd4a9 100644
--- a/compiler/src/dotty/tools/dotc/core/Names.scala
+++ b/compiler/src/dotty/tools/dotc/core/Names.scala
@@ -16,6 +16,8 @@ import util.{DotClass}
 import config.Config
 import java.util.HashMap
 
+import scala.annotation.internal.sharable
+
 object Names {
   import NameKinds._
 
diff --git a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
index f64980e6c9a2..7672c055e4ba 100644
--- a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -24,6 +24,8 @@ import reporting.diagnostic.Message
 import reporting.diagnostic.messages.BadSymbolicReference
 import reporting.trace
 
+import scala.annotation.internal.sharable
+
 trait SymDenotations { this: Context =>
   import SymDenotations._
 
diff --git a/compiler/src/dotty/tools/dotc/core/Symbols.scala b/compiler/src/dotty/tools/dotc/core/Symbols.scala
index f00ca26f215e..271215777c04 100644
--- a/compiler/src/dotty/tools/dotc/core/Symbols.scala
+++ b/compiler/src/dotty/tools/dotc/core/Symbols.scala
@@ -31,6 +31,7 @@ import io.AbstractFile
 import language.implicitConversions
 import util.{NoSource, DotClass, Property}
 import scala.collection.JavaConverters._
+import scala.annotation.internal.sharable
 import config.Printers.typr
 
 /** Creation methods for symbols */
diff --git a/compiler/src/dotty/tools/dotc/core/TypeOps.scala b/compiler/src/dotty/tools/dotc/core/TypeOps.scala
index ce039351201f..af13b3f22ed5 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeOps.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeOps.scala
@@ -19,6 +19,8 @@ import ast.tpd._
 import reporting.trace
 import reporting.diagnostic.Message
 
+import scala.annotation.internal.sharable
+
 trait TypeOps { this: Context => // TODO: Make standalone object.
 
   /** The type `tp` as seen from prefix `pre` and owner `cls`. See the spec
diff --git a/compiler/src/dotty/tools/dotc/core/TyperState.scala b/compiler/src/dotty/tools/dotc/core/TyperState.scala
index 6ae682ee5e2e..d176e5eddd99 100644
--- a/compiler/src/dotty/tools/dotc/core/TyperState.scala
+++ b/compiler/src/dotty/tools/dotc/core/TyperState.scala
@@ -14,6 +14,8 @@ import collection.mutable
 import java.lang.ref.WeakReference
 import Decorators._
 
+import scala.annotation.internal.sharable
+
 object TyperState {
   @sharable private var nextId: Int = 0
 }
diff --git a/compiler/src/dotty/tools/dotc/core/Types.scala b/compiler/src/dotty/tools/dotc/core/Types.scala
index 9b293c01791a..948c0bfc1606 100644
--- a/compiler/src/dotty/tools/dotc/core/Types.scala
+++ b/compiler/src/dotty/tools/dotc/core/Types.scala
@@ -36,6 +36,8 @@ import scala.util.hashing.{ MurmurHash3 => hashing }
 import config.Printers.{core, typr}
 import java.lang.ref.WeakReference
 
+import scala.annotation.internal.sharable
+
 object Types {
 
   @sharable private[this] var nextId = 0
diff --git a/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala b/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
index 0602b770233a..49459ac9f0e3 100644
--- a/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
+++ b/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
@@ -755,6 +755,20 @@ class ClassfileParser(
       }
 
       def unpickleScala(bytes: Array[Byte]): Some[Embedded] = {
+        val allowed = ctx.settings.Yscala2Unpickler.value
+
+        def failUnless(cond: Boolean) =
+          assert(cond,
+            s"Unpickling ${classRoot.symbol.showLocated} from ${classRoot.symbol.associatedFile} is not allowed with -Yscala2-unpickler $allowed")
+
+        if (allowed != "always") {
+          failUnless(allowed != "never")
+          val allowedList = allowed.split(":").toList
+          val file = classRoot.symbol.associatedFile
+          // Using `.toString.contains` isn't great, but it's good enough for a debug flag.
+          failUnless(file == null || allowedList.exists(path => file.toString.contains(path)))
+        }
+
         val unpickler = new unpickleScala2.Scala2Unpickler(bytes, classRoot, moduleRoot)(ctx)
         unpickler.run()(ctx.addMode(Scala2UnpicklingMode))
         Some(unpickler)
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
index aafad008fef6..79227028e1e1 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
@@ -25,6 +25,8 @@ import scala.quoted
 import scala.quoted.Types.TreeType
 import scala.quoted.Exprs.TastyTreeExpr
 
+import scala.annotation.internal.sharable
+
 /** Unpickler for typed trees
  *  @param reader              the reader from which to unpickle
  *  @param posUnpicklerOpt     the unpickler for positions, if it exists
diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
index a340d9160150..8c4254c2b5f5 100644
--- a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -2,6 +2,7 @@ package dotty.tools
 package dotc
 package parsing
 
+import scala.annotation.internal.sharable
 import scala.collection.mutable.ListBuffer
 import scala.collection.immutable.BitSet
 import util.{ SourceFile, SourcePosition }
diff --git a/compiler/src/dotty/tools/dotc/printing/Printer.scala b/compiler/src/dotty/tools/dotc/printing/Printer.scala
index f054a3dcb357..fc011b9f1ab5 100644
--- a/compiler/src/dotty/tools/dotc/printing/Printer.scala
+++ b/compiler/src/dotty/tools/dotc/printing/Printer.scala
@@ -9,6 +9,8 @@ import Types.Type, Symbols.Symbol, Contexts.Context, Scopes.Scope, Constants.Con
 import typer.Implicits.SearchResult
 import typer.ImportInfo
 
+import scala.annotation.internal.sharable
+
 /** The base class of all printers
  */
 abstract class Printer {
diff --git a/compiler/src/dotty/tools/dotc/reporting/Reporter.scala b/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
index 16041eb32340..4e556af7ea5c 100644
--- a/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -2,6 +2,8 @@ package dotty.tools
 package dotc
 package reporting
 
+import scala.annotation.internal.sharable
+
 import core.Contexts._
 import util.{SourcePosition, NoSourcePosition}
 import core.Decorators.PhaseListDecorator
diff --git a/compiler/src/dotty/tools/dotc/transform/CheckReentrant.scala b/compiler/src/dotty/tools/dotc/transform/CheckReentrant.scala
index c60d8edf04fc..49be540f92ab 100644
--- a/compiler/src/dotty/tools/dotc/transform/CheckReentrant.scala
+++ b/compiler/src/dotty/tools/dotc/transform/CheckReentrant.scala
@@ -50,9 +50,9 @@ class CheckReentrant extends MiniPhase {
   private[this] var indent: Int = 0
 
   private val sharableAnnot = new CtxLazy(implicit ctx =>
-    ctx.requiredClass("dotty.tools.sharable"))
+    ctx.requiredClass("scala.annotation.internal.sharable"))
   private val unsharedAnnot = new CtxLazy(implicit ctx =>
-    ctx.requiredClass("dotty.tools.unshared"))
+    ctx.requiredClass("scala.annotation.internal.unshared"))
 
   def isIgnored(sym: Symbol)(implicit ctx: Context) =
     sym.hasAnnotation(sharableAnnot()) ||
@@ -92,4 +92,4 @@ class CheckReentrant extends MiniPhase {
       addVars(tree.symbol.owner.asClass)
     tree
   }
-}
\ No newline at end of file
+}
diff --git a/compiler/src/dotty/tools/dotc/typer/Implicits.scala b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
index c3e5ab431213..a1cd253a26fd 100644
--- a/compiler/src/dotty/tools/dotc/typer/Implicits.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
@@ -37,6 +37,8 @@ import config.Printers.{implicits, implicitsDetailed, typr}
 import collection.mutable
 import reporting.trace
 
+import scala.annotation.internal.sharable
+
 /** Implicit resolution */
 object Implicits {
   import tpd._
diff --git a/compiler/src/dotty/tools/dotc/typer/Inferencing.scala b/compiler/src/dotty/tools/dotc/typer/Inferencing.scala
index 151aae7ff77e..66adb91941b1 100644
--- a/compiler/src/dotty/tools/dotc/typer/Inferencing.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Inferencing.scala
@@ -22,6 +22,8 @@ import reporting._
 import collection.mutable
 import config.Config
 
+import scala.annotation.internal.sharable
+
 object Inferencing {
 
   import tpd._
diff --git a/compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala b/compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala
index fe902a13de51..e592d3b2517d 100644
--- a/compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala
+++ b/compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala
@@ -19,6 +19,8 @@ import ErrorReporting.errorType
 import config.Printers.typr
 import collection.mutable
 
+import scala.annotation.internal.sharable
+
 object ProtoTypes {
 
   import tpd._
diff --git a/compiler/src/dotty/tools/dotc/util/NameTransformer.scala b/compiler/src/dotty/tools/dotc/util/NameTransformer.scala
index 18c5b09823b2..65e9fef8ddb8 100644
--- a/compiler/src/dotty/tools/dotc/util/NameTransformer.scala
+++ b/compiler/src/dotty/tools/dotc/util/NameTransformer.scala
@@ -7,6 +7,8 @@ import core.Decorators._
 import collection.mutable
 import util.Chars.isValidJVMMethodChar
 
+import scala.annotation.internal.sharable
+
 /** Provides functions to encode and decode Scala symbolic names.
  */
 object NameTransformer {
diff --git a/compiler/src/dotty/tools/dotc/util/SourceFile.scala b/compiler/src/dotty/tools/dotc/util/SourceFile.scala
index d80c49617290..d7cafdaba633 100644
--- a/compiler/src/dotty/tools/dotc/util/SourceFile.scala
+++ b/compiler/src/dotty/tools/dotc/util/SourceFile.scala
@@ -11,6 +11,7 @@ import Chars._
 import ScriptSourceFile._
 import Positions._
 import scala.io.Codec
+import scala.annotation.internal.sharable
 
 import java.util.Optional
 
diff --git a/compiler/src/dotty/tools/dotc/util/SourcePosition.scala b/compiler/src/dotty/tools/dotc/util/SourcePosition.scala
index 89aa413f6308..06f4ccc6e1f5 100644
--- a/compiler/src/dotty/tools/dotc/util/SourcePosition.scala
+++ b/compiler/src/dotty/tools/dotc/util/SourcePosition.scala
@@ -4,6 +4,8 @@ package util
 
 import Positions.{Position, NoPosition}
 
+import scala.annotation.internal.sharable
+
 /** A source position is comprised of a position in a source file */
 case class SourcePosition(source: SourceFile, pos: Position, outer: SourcePosition = NoSourcePosition)
 extends interfaces.SourcePosition {
diff --git a/compiler/src/dotty/tools/dotc/util/Stats.scala b/compiler/src/dotty/tools/dotc/util/Stats.scala
index 38f0fa0db99d..283fce5279e0 100644
--- a/compiler/src/dotty/tools/dotc/util/Stats.scala
+++ b/compiler/src/dotty/tools/dotc/util/Stats.scala
@@ -2,6 +2,8 @@ package dotty.tools
 package dotc
 package util
 
+import scala.annotation.internal.sharable
+
 import core.Contexts._
 import collection.mutable
 
diff --git a/compiler/src/dotty/tools/package.scala b/compiler/src/dotty/tools/package.scala
index 220eb6b7588b..d0501e53fed8 100644
--- a/compiler/src/dotty/tools/package.scala
+++ b/compiler/src/dotty/tools/package.scala
@@ -2,9 +2,6 @@ package dotty
 import scala.annotation.Annotation
 
 package object tools {
-  class sharable extends Annotation
-  class unshared extends Annotation
-
   // Ensure this object is already classloaded, since it's only actually used
   // when handling stack overflows and every operation (including class loading)
   // risks failing.
diff --git a/compiler/src/dotty/tools/repl/ParseResult.scala b/compiler/src/dotty/tools/repl/ParseResult.scala
index 40f76d77ca32..2722cd5f6b2e 100644
--- a/compiler/src/dotty/tools/repl/ParseResult.scala
+++ b/compiler/src/dotty/tools/repl/ParseResult.scala
@@ -11,6 +11,8 @@ import dotc.reporting._
 
 import results._
 
+import scala.annotation.internal.sharable
+
 /** A parsing result from string input */
 sealed trait ParseResult
 
diff --git a/compiler/test/dotty/Jars.scala b/compiler/test/dotty/Jars.scala
index 1c80b02b7c86..4959fc95aa2f 100644
--- a/compiler/test/dotty/Jars.scala
+++ b/compiler/test/dotty/Jars.scala
@@ -18,6 +18,10 @@ object Jars {
   lazy val scalaAsm: String =
     findJarFromRuntime("scala-asm-6.0.0-scala-1")
 
+  /** scala-xml jar */
+  lazy val scalaXml: String =
+    findJarFromRuntime("scala-xml")
+
   /** JLine Jar */
   lazy val jline: String =
     findJarFromRuntime("jline-3.7.0")
diff --git a/compiler/test/dotty/TestCategories.scala b/compiler/test/dotty/TestCategories.scala
index d7a011719637..696912ff9495 100644
--- a/compiler/test/dotty/TestCategories.scala
+++ b/compiler/test/dotty/TestCategories.scala
@@ -5,3 +5,6 @@ trait SlowTests
 
 /** Meta tests category for JUnit */
 trait VulpixMetaTests
+
+/** Tests that should only be run with a bootstrapped compiler */
+trait BootstrappedOnlyTests
diff --git a/compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala b/compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala
new file mode 100644
index 000000000000..0eaf9368c159
--- /dev/null
+++ b/compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala
@@ -0,0 +1,115 @@
+package dotty
+package tools
+package dotc
+
+import org.junit.{ Test, BeforeClass, AfterClass }
+import org.junit.Assert._
+import org.junit.Assume._
+import org.junit.experimental.categories.Category
+
+import java.nio.file._
+import java.util.stream.{ Stream => JStream }
+import scala.collection.JavaConverters._
+import scala.util.matching.Regex
+import scala.concurrent.duration._
+import vulpix._
+import dotty.tools.io.JFile
+
+@Category(Array(classOf[BootstrappedOnlyTests]))
+class BootstrappedOnlyCompilationTests extends ParallelTesting {
+  import ParallelTesting._
+  import TestConfiguration._
+  import CompilationTests._
+
+  // Test suite configuration --------------------------------------------------
+
+  def maxDuration = 30.seconds
+  def numberOfSlaves = 5
+  def safeMode = Properties.testsSafeMode
+  def isInteractive = SummaryReport.isInteractive
+  def testFilter = Properties.testsFilter
+
+  // Positive tests ------------------------------------------------------------
+
+  @Test def posWithCompiler: Unit = {
+    implicit val testGroup: TestGroup = TestGroup("compilePosWithCompiler")
+    compileFilesInDir("tests/pos-with-compiler", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/ast", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/config", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/core", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/transform", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/parsing", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/printing", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/reporting", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/typer", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/util", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/io", defaultOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/core", TestFlags(classPath, noCheckOptions))
+  }
+
+  @Test def posTwiceWithCompiler: Unit = {
+    implicit val testGroup: TestGroup = TestGroup("posTwiceWithCompiler")
+    compileFile("tests/pos-with-compiler/Labels.scala", defaultOptions) +
+    compileFile("tests/pos-with-compiler/Patterns.scala", defaultOptions) +
+    compileList(
+      "testNonCyclic",
+      List(
+        "compiler/src/dotty/tools/dotc/CompilationUnit.scala",
+        "compiler/src/dotty/tools/dotc/core/Types.scala",
+        "compiler/src/dotty/tools/dotc/ast/Trees.scala"
+      ),
+      defaultOptions.and("-Xprompt")
+    ) +
+    compileList(
+      "testIssue34",
+      List(
+        "compiler/src/dotty/tools/dotc/config/Properties.scala",
+        "compiler/src/dotty/tools/dotc/config/PathResolver.scala"
+      ),
+      defaultOptions.and("-Xprompt")
+    )
+  }.times(2).checkCompile()
+
+  // Negative tests ------------------------------------------------------------
+
+  @Test def negAll: Unit = {
+    implicit val testGroup: TestGroup = TestGroup("compileNegWithCompiler")
+    compileFilesInDir("tests/neg-with-compiler", defaultOptions)
+  }.checkExpectedErrors()
+
+  // Run tests -----------------------------------------------------------------
+
+  @Test def runWithCompiler: Unit = {
+    implicit val testGroup: TestGroup = TestGroup("runWithCompiler")
+    compileFilesInDir("tests/run-with-compiler", defaultRunWithCompilerOptions) +
+    compileFile("tests/run-with-compiler-custom-args/staged-streams_1.scala", defaultRunWithCompilerOptions without "-Yno-deep-subtypes")
+  }.checkRuns()
+
+  // Pickling Tests ------------------------------------------------------------
+  //
+  // Pickling tests are very memory intensive and as such need to be run with a
+  // lower level of concurrency as to not kill their running VMs
+
+  @Test def picklingWithCompiler: Unit = {
+    implicit val testGroup: TestGroup = TestGroup("testPicklingWithCompiler")
+    compileDir("compiler/src/dotty/tools", picklingOptions, recursive = false) +
+    compileDir("compiler/src/dotty/tools/dotc", picklingOptions, recursive = false) +
+    compileDir("library/src/dotty/runtime", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/backend/jvm", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/ast", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/core", picklingOptions, recursive = false) +
+    compileDir("compiler/src/dotty/tools/dotc/config", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/parsing", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/printing", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/repl", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/rewrite", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/transform", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/typer", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/util", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/io", picklingOptions) +
+    compileFile("tests/pos/pickleinf.scala", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/core/classfile", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/core/tasty", picklingOptions) +
+    compileDir("compiler/src/dotty/tools/dotc/core/unpickleScala2", picklingOptions)
+  }.limitThreads(4).checkCompile()
+}
diff --git a/compiler/test/dotty/tools/dotc/CompilationTests.scala b/compiler/test/dotty/tools/dotc/CompilationTests.scala
index 10055f39aa72..90521d3acca4 100644
--- a/compiler/test/dotty/tools/dotc/CompilationTests.scala
+++ b/compiler/test/dotty/tools/dotc/CompilationTests.scala
@@ -37,20 +37,9 @@ class CompilationTests extends ParallelTesting {
     compileList("compileStdLib", TestSources.stdLibWhitelisted, scala2Mode.and("-migration", "-Yno-inline", "-Ydetailed-stats"))
   }.checkCompile()
 
-  @Test def compilePos: Unit = {
+  @Test def pos: Unit = {
     implicit val testGroup: TestGroup = TestGroup("compilePos")
     compileList("compileStdLib", TestSources.stdLibWhitelisted, scala2Mode.and("-migration", "-Yno-inline")) +
-    compileDir("compiler/src/dotty/tools/dotc/ast", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/config", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/core", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/transform", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/parsing", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/printing", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/reporting", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/typer", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/util", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/io", defaultOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/core", TestFlags(classPath, noCheckOptions)) +
     compileFile("tests/pos/nullarify.scala", defaultOptions.and("-Ycheck:nullarify")) +
     compileFile("tests/pos-scala2/rewrites.scala", scala2Mode.and("-rewrite")).copyToTarget() +
     compileFile("tests/pos-special/utf8encoded.scala", explicitUTF8) +
@@ -111,7 +100,6 @@ class CompilationTests extends ParallelTesting {
 
   @Test def posTwice: Unit = {
     implicit val testGroup: TestGroup = TestGroup("posTwice")
-    compileFile("tests/pos/Labels.scala", defaultOptions) +
     compileFilesInDir("tests/pos-java-interop", defaultOptions) +
     compileFilesInDir("tests/pos-java-interop-separate", defaultOptions) +
     compileFile("tests/pos/t2168.scala", defaultOptions) +
@@ -122,7 +110,6 @@ class CompilationTests extends ParallelTesting {
     compileFile("tests/pos/functions1.scala", defaultOptions) +
     compileFile("tests/pos/implicits1.scala", defaultOptions) +
     compileFile("tests/pos/inferred.scala", defaultOptions) +
-    compileFile("tests/pos/Patterns.scala", defaultOptions) +
     compileFile("tests/pos/selftypes.scala", defaultOptions) +
     compileFile("tests/pos/varargs.scala", defaultOptions) +
     compileFile("tests/pos/vararg-pattern.scala", defaultOptions) +
@@ -147,29 +134,12 @@ class CompilationTests extends ParallelTesting {
     compileFile("tests/pos/i0239.scala", defaultOptions) +
     compileFile("tests/pos/anonClassSubtyping.scala", defaultOptions) +
     compileFile("tests/pos/extmethods.scala", defaultOptions) +
-    compileFile("tests/pos/companions.scala", defaultOptions) +
-    compileList(
-      "testNonCyclic",
-      List(
-        "compiler/src/dotty/tools/dotc/CompilationUnit.scala",
-        "compiler/src/dotty/tools/dotc/core/Types.scala",
-        "compiler/src/dotty/tools/dotc/ast/Trees.scala"
-      ),
-      defaultOptions.and("-Xprompt")
-    ) +
-    compileList(
-      "testIssue34",
-      List(
-        "compiler/src/dotty/tools/dotc/config/Properties.scala",
-        "compiler/src/dotty/tools/dotc/config/PathResolver.scala"
-      ),
-      defaultOptions.and("-Xprompt")
-    )
+    compileFile("tests/pos/companions.scala", defaultOptions)
   }.times(2).checkCompile()
 
   // Negative tests ------------------------------------------------------------
 
-  @Test def compileNeg: Unit = {
+  @Test def negAll: Unit = {
     implicit val testGroup: TestGroup = TestGroup("compileNeg")
     compileFilesInDir("tests/neg", defaultOptions) +
     compileFilesInDir("tests/neg-tailcall", defaultOptions) +
@@ -195,9 +165,7 @@ class CompilationTests extends ParallelTesting {
 
   @Test def runAll: Unit = {
     implicit val testGroup: TestGroup = TestGroup("runAll")
-    compileFilesInDir("tests/run", defaultOptions) +
-    compileFilesInDir("tests/run-with-compiler", defaultRunWithCompilerOptions) +
-    compileFile("tests/run-with-compiler-custom-args/staged-streams_1.scala", defaultRunWithCompilerOptions without "-Yno-deep-subtypes")
+    compileFilesInDir("tests/run", defaultOptions)
   }.checkRuns()
 
   // Generic java signatures tests ---------------------------------------------
@@ -208,34 +176,12 @@ class CompilationTests extends ParallelTesting {
   }.checkRuns()
 
   // Pickling Tests ------------------------------------------------------------
-  //
-  // Pickling tests are very memory intensive and as such need to be run with a
-  // lower level of concurrency as to not kill their running VMs
 
-  @Test def testPickling: Unit = {
+  @Test def pickling: Unit = {
     implicit val testGroup: TestGroup = TestGroup("testPickling")
-    compileDir("compiler/src/dotty/tools", picklingOptions, recursive = false) +
-    compileDir("compiler/src/dotty/tools/dotc", picklingOptions, recursive = false) +
     compileFilesInDir("tests/new", picklingOptions) +
-    compileFilesInDir("tests/pickling", picklingOptions) +
-    compileDir("library/src/dotty/runtime", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/backend/jvm", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/ast", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/core", picklingOptions, recursive = false) +
-    compileDir("compiler/src/dotty/tools/dotc/config", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/parsing", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/printing", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/repl", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/rewrite", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/transform", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/typer", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/util", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/io", picklingOptions) +
-    compileFile("tests/pos/pickleinf.scala", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/core/classfile", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/core/tasty", picklingOptions) +
-    compileDir("compiler/src/dotty/tools/dotc/core/unpickleScala2", picklingOptions)
-  }.limitThreads(4).checkCompile()
+    compileFilesInDir("tests/pickling", picklingOptions)
+  }.checkCompile()
 
   /** The purpose of this test is two-fold, being able to compile dotty
    *  bootstrapped, and making sure that TASTY can link against a compiled
diff --git a/compiler/test/dotty/tools/vulpix/TestConfiguration.scala b/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
index 3d389597a226..de95fef27792 100644
--- a/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
+++ b/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
@@ -10,6 +10,7 @@ object TestConfiguration {
   )
 
   val checkOptions = Array(
+    "-Yscala2-unpickler", s"${Jars.scalaLibrary}:${Jars.scalaXml}",
     "-Yno-deep-subtypes",
     "-Yno-double-bindings",
     "-Yforce-sbt-phases",
diff --git a/library/src/scala/annotation/internal/sharable.scala b/library/src/scala/annotation/internal/sharable.scala
new file mode 100644
index 000000000000..e2d6dcc61beb
--- /dev/null
+++ b/library/src/scala/annotation/internal/sharable.scala
@@ -0,0 +1,9 @@
+package scala.annotation.internal
+
+import scala.annotation.Annotation
+
+/** An annotation indicating to `-Ycheck:reentrant` that a class or val can be safely shared.
+ *
+ *  @see scala.annotation.internal.unshared
+ */
+class sharable extends Annotation
diff --git a/library/src/scala/annotation/internal/unshared.scala b/library/src/scala/annotation/internal/unshared.scala
new file mode 100644
index 000000000000..89796eba09e3
--- /dev/null
+++ b/library/src/scala/annotation/internal/unshared.scala
@@ -0,0 +1,9 @@
+package scala.annotation.internal
+
+import scala.annotation.Annotation
+
+/** An annotation indicating to `-Ycheck:reentrant` that an object will not be accessed from multiple threads.
+ *
+ *  @see scala.annotation.internal.sharable
+ */
+class unshared extends Annotation
diff --git a/project/Build.scala b/project/Build.scala
index 42c942a96b33..f34e0a5be20f 100644
--- a/project/Build.scala
+++ b/project/Build.scala
@@ -227,6 +227,13 @@ object Build {
     // otherwise sbt 0.13 incremental compilation breaks (https://github.com/sbt/sbt/issues/3142)
     scalacOptions ++= Seq("-bootclasspath", sys.props("sun.boot.class.path")),
 
+    // Enforce that the only Scala 2 classfiles we unpickle come from scala-library
+    scalacOptions ++= {
+      val attList = (dependencyClasspath in `dotty-library` in Compile).value
+      val scalaLib = findLib(attList, "scala-library")
+      Seq("-Yscala2-unpickler", scalaLib)
+    },
+
     // sbt gets very unhappy if two projects use the same target
     target := baseDirectory.value / ".." / "out" / "bootstrap" / name.value,
 
@@ -427,6 +434,11 @@ object Build {
     (testOnly in Test).toTask(cmd)
   }
 
+  def findLib(attList: Seq[Attributed[File]], name: String) = attList
+    .map(_.data.getAbsolutePath)
+    .find(_.contains(name))
+    .toList.mkString(":")
+
   // Settings shared between dotty-compiler and dotty-compiler-bootstrapped
   lazy val commonDottyCompilerSettings = Seq(
 
@@ -518,7 +530,8 @@ object Build {
       },
 
       testOptions in Test += Tests.Argument(
-        TestFrameworks.JUnit, "--run-listener=dotty.tools.ContextEscapeDetector"
+        TestFrameworks.JUnit,
+        "--run-listener=dotty.tools.ContextEscapeDetector",
       ),
 
       // Spawn new JVM in run and test
@@ -573,7 +586,7 @@ object Build {
         jarOpts ::: tuning ::: agentOptions ::: ci_build ::: path.toList
       },
 
-      testCompilation := testOnlyFiltered("dotty.tools.dotc.CompilationTests", "--exclude-categories=dotty.SlowTests").evaluated,
+      testCompilation := testOnlyFiltered("dotty.tools.dotc.*CompilationTests", "--exclude-categories=dotty.SlowTests").evaluated,
       testFromTasty := testOnlyFiltered("dotty.tools.dotc.FromTastyTests", "").evaluated,
 
       dotr := {
@@ -581,12 +594,7 @@ object Build {
         val attList = (dependencyClasspath in Runtime).value
         val jars = packageAll.value
 
-        def findLib(name: String) = attList
-          .map(_.data.getAbsolutePath)
-          .find(_.contains(name))
-          .toList.mkString(":")
-
-        val scalaLib = findLib("scala-library")
+        val scalaLib = findLib(attList, "scala-library")
         val dottyLib = jars("dotty-library")
 
         def run(args: List[String]): Unit = {
@@ -599,8 +607,11 @@ object Build {
         } else if (scalaLib == "") {
           println("Couldn't find scala-library on classpath, please run using script in bin dir instead")
         } else if (args.contains("-with-compiler")) {
+          if (!isDotty.value) {
+            throw new MessageOnlyException("-with-compiler can only be used with a bootstrapped compiler")
+          }
           val args1 = args.filter(_ != "-with-compiler")
-          val asm = findLib("scala-asm")
+          val asm = findLib(attList, "scala-asm")
           val dottyCompiler = jars("dotty-compiler")
           val dottyInterfaces = jars("dotty-interfaces")
           run(insertClasspathInArgs(args1, s"$dottyCompiler:$dottyInterfaces:$asm"))
@@ -664,7 +675,12 @@ object Build {
 
     var extraClasspath = dottyLib
     if ((decompile || printTasty) && !args.contains("-classpath")) extraClasspath += ":."
-    if (args0.contains("-with-compiler")) extraClasspath += s":$dottyCompiler"
+    if (args0.contains("-with-compiler")) {
+      if (!isDotty.value) {
+        throw new MessageOnlyException("-with-compiler can only be used with a bootstrapped compiler")
+      }
+      extraClasspath += s":$dottyCompiler"
+    }
 
     val fullArgs = main :: insertClasspathInArgs(args, extraClasspath)
 
@@ -679,21 +695,31 @@ object Build {
 
   lazy val nonBootstrapedDottyCompilerSettings = commonDottyCompilerSettings ++ Seq(
     // packageAll packages all and then returns a map with the abs location
-    packageAll := {
-      Map(
-        "dotty-interfaces"    -> packageBin.in(`dotty-interfaces`, Compile).value,
-        "dotty-compiler"      -> packageBin.in(Compile).value,
-        "dotty-library"       -> packageBin.in(`dotty-library`, Compile).value,
-        "dotty-compiler-test" -> packageBin.in(Test).value
-      ).mapValues(_.getAbsolutePath)
-    }
+    packageAll := Def.taskDyn { // Use a dynamic task to avoid loops when loading the settings
+      Def.task {
+        Map(
+          "dotty-interfaces"    -> packageBin.in(`dotty-interfaces`, Compile).value,
+          "dotty-compiler"      -> packageBin.in(Compile).value,
+
+          // NOTE: Using dotty-library-bootstrapped here is intentional: when
+          // running the compiler, we should always have the bootstrapped
+          // library on the compiler classpath since the non-bootstrapped one
+          // may not be binary-compatible.
+          "dotty-library"       -> packageBin.in(`dotty-library-bootstrapped`, Compile).value
+        ).mapValues(_.getAbsolutePath)
+      }
+    }.value,
+
+    testOptions in Test += Tests.Argument(
+      TestFrameworks.JUnit,
+      "--exclude-categories=dotty.BootstrappedOnlyTests",
+    ),
   )
 
   lazy val bootstrapedDottyCompilerSettings = commonDottyCompilerSettings ++ Seq(
     packageAll := {
       packageAll.in(`dotty-compiler`).value ++ Seq(
-        "dotty-compiler" -> packageBin.in(Compile).value.getAbsolutePath,
-        "dotty-library"  -> packageBin.in(`dotty-library-bootstrapped`, Compile).value.getAbsolutePath
+        "dotty-compiler" -> packageBin.in(Compile).value.getAbsolutePath
       )
     }
   )
@@ -756,6 +782,21 @@ object Build {
 
   lazy val `dotty-sbt-bridge` = project.in(file("sbt-bridge")).asDottySbtBridge(NonBootstrapped)
   lazy val `dotty-sbt-bridge-bootstrapped` = project.in(file("sbt-bridge")).asDottySbtBridge(Bootstrapped)
+    .settings(
+      // Tweak -Yscala2-unpickler to allow some sbt dependencies used in tests
+      scalacOptions in Test := {
+        val oldOptions = (scalacOptions in Test).value
+        val i = oldOptions.indexOf("-Yscala2-unpickler")
+        assert(i != -1)
+        val oldValue = oldOptions(i + 1)
+
+        val attList = (dependencyClasspath in Test).value
+        val sbtIo = findLib(attList, "org.scala-sbt/io")
+        val zincApiInfo = findLib(attList, "zinc-apiinfo")
+
+        oldOptions.updated(i + 1, s"$sbtIo:$zincApiInfo:$oldValue")
+      }
+    )
 
   lazy val `dotty-language-server` = project.in(file("language-server")).
     dependsOn(dottyCompiler(Bootstrapped)).
diff --git a/project/scripts/cmdTests b/project/scripts/cmdTests
index 203b8e78fa01..1933812f2c17 100755
--- a/project/scripts/cmdTests
+++ b/project/scripts/cmdTests
@@ -8,7 +8,6 @@ SBT="./project/scripts/sbt" # if run on CI
 SOURCE="tests/pos/HelloWorld.scala"
 MAIN="HelloWorld"
 EXPECTED_OUTPUT="hello world"
-COMPILER_CP="compiler/target/scala-2.12/classes" # FIXME: This is not very reliable
 
 # check that benchmarks can run
 "$SBT" "dotty-bench/jmh:run 1 1 tests/pos/alias.scala"
@@ -51,7 +50,7 @@ clear_out "$OUT"
 grep -qe "def main(args: scala.Array\[scala.Predef.String\]): scala.Unit =" "$tmp"
 
 echo "testing scala.quoted.Expr.run from sbt dotr"
-"$SBT" ";dotty-compiler/compile ;dotc -classpath $COMPILER_CP tests/run-with-compiler/quote-run.scala; dotr -with-compiler Test" > "$tmp"
+"$SBT" ";dotty-compiler-bootstrapped/dotc -with-compiler tests/run-with-compiler/quote-run.scala; dotty-compiler-bootstrapped/dotr -with-compiler Test" > "$tmp"
 grep -qe "val a: scala.Int = 3" "$tmp"
 
 
diff --git a/tests/neg/Main.scala b/tests/neg-with-compiler/Main.scala
similarity index 100%
rename from tests/neg/Main.scala
rename to tests/neg-with-compiler/Main.scala
diff --git a/tests/neg/quote-run-in-macro-1/quoted_1.scala b/tests/neg-with-compiler/quote-run-in-macro-1/quoted_1.scala
similarity index 100%
rename from tests/neg/quote-run-in-macro-1/quoted_1.scala
rename to tests/neg-with-compiler/quote-run-in-macro-1/quoted_1.scala
diff --git a/tests/neg/quote-run-in-macro-1/quoted_2.scala b/tests/neg-with-compiler/quote-run-in-macro-1/quoted_2.scala
similarity index 100%
rename from tests/neg/quote-run-in-macro-1/quoted_2.scala
rename to tests/neg-with-compiler/quote-run-in-macro-1/quoted_2.scala
diff --git a/tests/neg/quote-run-in-macro-2/quoted_1.scala b/tests/neg-with-compiler/quote-run-in-macro-2/quoted_1.scala
similarity index 100%
rename from tests/neg/quote-run-in-macro-2/quoted_1.scala
rename to tests/neg-with-compiler/quote-run-in-macro-2/quoted_1.scala
diff --git a/tests/neg/quote-run-in-macro-2/quoted_2.scala b/tests/neg-with-compiler/quote-run-in-macro-2/quoted_2.scala
similarity index 100%
rename from tests/neg/quote-run-in-macro-2/quoted_2.scala
rename to tests/neg-with-compiler/quote-run-in-macro-2/quoted_2.scala
diff --git a/tests/pickling/A.scala b/tests/pos-with-compiler/A.scala
similarity index 100%
rename from tests/pickling/A.scala
rename to tests/pos-with-compiler/A.scala
diff --git a/tests/pickling/B.scala b/tests/pos-with-compiler/B.scala
similarity index 100%
rename from tests/pickling/B.scala
rename to tests/pos-with-compiler/B.scala
diff --git a/tests/pos/Fileish.scala b/tests/pos-with-compiler/Fileish.scala
similarity index 100%
rename from tests/pos/Fileish.scala
rename to tests/pos-with-compiler/Fileish.scala
diff --git a/tests/pos/Labels.scala b/tests/pos-with-compiler/Labels.scala
similarity index 100%
rename from tests/pos/Labels.scala
rename to tests/pos-with-compiler/Labels.scala
diff --git a/tests/pos/Patterns.scala b/tests/pos-with-compiler/Patterns.scala
similarity index 100%
rename from tests/pos/Patterns.scala
rename to tests/pos-with-compiler/Patterns.scala
diff --git a/tests/pos/i143.scala b/tests/pos-with-compiler/i143.scala
similarity index 100%
rename from tests/pos/i143.scala
rename to tests/pos-with-compiler/i143.scala
diff --git a/tests/pos/quote-0.scala b/tests/pos-with-compiler/quote-0.scala
similarity index 100%
rename from tests/pos/quote-0.scala
rename to tests/pos-with-compiler/quote-0.scala
diff --git a/tests/pos/quote-assert/quoted_1.scala b/tests/pos-with-compiler/quote-assert/quoted_1.scala
similarity index 100%
rename from tests/pos/quote-assert/quoted_1.scala
rename to tests/pos-with-compiler/quote-assert/quoted_1.scala
diff --git a/tests/pos/quote-assert/quoted_2.scala b/tests/pos-with-compiler/quote-assert/quoted_2.scala
similarity index 100%
rename from tests/pos/quote-assert/quoted_2.scala
rename to tests/pos-with-compiler/quote-assert/quoted_2.scala
diff --git a/tests/pos/tasty/definitions.scala b/tests/pos-with-compiler/tasty/definitions.scala
similarity index 100%
rename from tests/pos/tasty/definitions.scala
rename to tests/pos-with-compiler/tasty/definitions.scala
diff --git a/tests/pos/lazyValsSepComp.scala b/tests/pos/lazyValsSepComp.scala
deleted file mode 100644
index 048231eb00c3..000000000000
--- a/tests/pos/lazyValsSepComp.scala
+++ /dev/null
@@ -1,16 +0,0 @@
-package dotty.tools
-package io
-
-import java.io.{ InputStream }
-import java.util.jar.JarEntry
-import dotty.tools.dotc.core.Definitions
-import language.postfixOps
-import dotty.tools.dotc.core.Contexts._
-
-
-/** A test to trigger issue with separate compilation between Dotty and Scalac and lazy vals */
-object Foo {
-  val definitions: Definitions = null
-  def defn = definitions
-  def go = defn.FunctionClassPerRun
-}
diff --git a/tests/run/quote-impure-by-name.check b/tests/run-with-compiler/quote-impure-by-name.check
similarity index 100%
rename from tests/run/quote-impure-by-name.check
rename to tests/run-with-compiler/quote-impure-by-name.check
diff --git a/tests/run/quote-impure-by-name/quoted_1.scala b/tests/run-with-compiler/quote-impure-by-name/quoted_1.scala
similarity index 100%
rename from tests/run/quote-impure-by-name/quoted_1.scala
rename to tests/run-with-compiler/quote-impure-by-name/quoted_1.scala
diff --git a/tests/run/quote-impure-by-name/quoted_2.scala b/tests/run-with-compiler/quote-impure-by-name/quoted_2.scala
similarity index 100%
rename from tests/run/quote-impure-by-name/quoted_2.scala
rename to tests/run-with-compiler/quote-impure-by-name/quoted_2.scala
diff --git a/tests/run/quote-inline-function.check b/tests/run-with-compiler/quote-inline-function.check
similarity index 100%
rename from tests/run/quote-inline-function.check
rename to tests/run-with-compiler/quote-inline-function.check
diff --git a/tests/run/quote-inline-function/quoted_1.scala b/tests/run-with-compiler/quote-inline-function/quoted_1.scala
similarity index 100%
rename from tests/run/quote-inline-function/quoted_1.scala
rename to tests/run-with-compiler/quote-inline-function/quoted_1.scala
diff --git a/tests/run/quote-inline-function/quoted_2.scala b/tests/run-with-compiler/quote-inline-function/quoted_2.scala
similarity index 100%
rename from tests/run/quote-inline-function/quoted_2.scala
rename to tests/run-with-compiler/quote-inline-function/quoted_2.scala
diff --git a/tests/run/quote-splice-interpret-1.check b/tests/run-with-compiler/quote-splice-interpret-1.check
similarity index 100%
rename from tests/run/quote-splice-interpret-1.check
rename to tests/run-with-compiler/quote-splice-interpret-1.check
diff --git a/tests/run/quote-splice-interpret-1/Macro_1.scala b/tests/run-with-compiler/quote-splice-interpret-1/Macro_1.scala
similarity index 100%
rename from tests/run/quote-splice-interpret-1/Macro_1.scala
rename to tests/run-with-compiler/quote-splice-interpret-1/Macro_1.scala
diff --git a/tests/run/quote-splice-interpret-1/Test_2.scala b/tests/run-with-compiler/quote-splice-interpret-1/Test_2.scala
similarity index 100%
rename from tests/run/quote-splice-interpret-1/Test_2.scala
rename to tests/run-with-compiler/quote-splice-interpret-1/Test_2.scala
diff --git a/tests/run/tasty-extractors-constants-2.check b/tests/run-with-compiler/tasty-extractors-constants-2.check
similarity index 100%
rename from tests/run/tasty-extractors-constants-2.check
rename to tests/run-with-compiler/tasty-extractors-constants-2.check
diff --git a/tests/run/tasty-extractors-constants-2/quoted_1.scala b/tests/run-with-compiler/tasty-extractors-constants-2/quoted_1.scala
similarity index 100%
rename from tests/run/tasty-extractors-constants-2/quoted_1.scala
rename to tests/run-with-compiler/tasty-extractors-constants-2/quoted_1.scala
diff --git a/tests/run/tasty-extractors-constants-2/quoted_2.scala b/tests/run-with-compiler/tasty-extractors-constants-2/quoted_2.scala
similarity index 100%
rename from tests/run/tasty-extractors-constants-2/quoted_2.scala
rename to tests/run-with-compiler/tasty-extractors-constants-2/quoted_2.scala
diff --git a/tests/run/lst/Lst.scala b/tests/run/lst/Lst.scala
index 3f6500d475dc..85ef6729c081 100644
--- a/tests/run/lst/Lst.scala
+++ b/tests/run/lst/Lst.scala
@@ -1,8 +1,5 @@
-package dotty.tools.dotc
-package util
+package lst
 
-import printing.{Printer, Texts}
-import Texts.Text
 import collection.mutable.{ListBuffer, StringBuilder}
 import collection.immutable.Map
 import reflect.ClassTag
diff --git a/tests/run/lst/LstTest.scala b/tests/run/lst/LstTest.scala
index 9f7c7a7ff1c6..8b1e7ad8b166 100644
--- a/tests/run/lst/LstTest.scala
+++ b/tests/run/lst/LstTest.scala
@@ -1,5 +1,5 @@
 object Test extends App {
-  import dotty.tools.dotc.util.Lst
+  import lst.Lst
 
   val xs0: Lst[String] = Lst.Empty
   val xs1 = Lst("a")