Check that dotty is reentrant

src/dotty/tools/dotc/Bench.scala

@@ -10,7 +10,7 @@ import reporting.Reporter
 
 object Bench extends Driver {
 
-  private var numRuns = 1
+  @sharable private var numRuns = 1
 
   def newCompiler(): Compiler = new Compiler
 

src/dotty/tools/dotc/Compiler.scala

@@ -40,7 +40,8 @@ class Compiler {
       List(new FrontEnd),
       List(new PostTyper),
       List(new Pickler),
-      List(new FirstTransform),
+      List(new FirstTransform,
+           new CheckReentrant),
       List(new RefChecks,
            new ElimRepeated,
            new NormalizeFlags,

src/dotty/tools/dotc/Resident.scala

@@ -21,7 +21,7 @@ import scala.annotation.tailrec
  *
  *  dotc> :q     // quit
  */
-object Resident extends Driver {
+class Resident extends Driver {
 
   object residentCompiler extends Compiler
 

src/dotty/tools/dotc/ast/Desugar.scala

@@ -209,7 +209,7 @@ object desugar {
     else tdef
   }
 
-  private val synthetic = Modifiers(Synthetic)
+  @sharable private val synthetic = Modifiers(Synthetic)
 
   private def toDefParam(tparam: TypeDef): TypeDef =
     tparam.withFlags(Param)

src/dotty/tools/dotc/ast/Trees.scala

@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package ast
 
 import core._
@@ -26,7 +27,7 @@ object Trees {
   type Untyped = Null
 
   /** The total number of created tree nodes, maintained if Stats.enabled */
-  var ntrees = 0
+  @sharable var ntrees = 0
 
   /** Modifiers and annotations for definitions
    *  @param flags          The set flags
@@ -68,7 +69,7 @@ object Trees {
     def tokenPos: Seq[(Token, Position)] = ???
   }
 
-  private var nextId = 0 // for debugging
+  @sharable private var nextId = 0 // for debugging
 
   type LazyTree = AnyRef     /* really: Tree | Lazy[Tree] */
   type LazyTreeList = AnyRef /* really: List[Tree] | Lazy[List[Tree]] */
@@ -723,9 +724,9 @@ object Trees {
     setMods(Modifiers[T](PrivateLocal))
   }
 
-  val theEmptyTree: Thicket[Type] = Thicket(Nil)
-  val theEmptyValDef = new EmptyValDef[Type]
-  val theEmptyModifiers = new Modifiers()
+  @sharable val theEmptyTree: Thicket[Type] = Thicket(Nil)
+  @sharable val theEmptyValDef = new EmptyValDef[Type]
+  @sharable val theEmptyModifiers = new Modifiers()
 
   def genericEmptyValDef[T >: Untyped]: ValDef[T]       = theEmptyValDef.asInstanceOf[ValDef[T]]
   def genericEmptyTree[T >: Untyped]: Thicket[T]        = theEmptyTree.asInstanceOf[Thicket[T]]
@@ -845,9 +846,9 @@ object Trees {
     type Annotated = Trees.Annotated[T]
     type Thicket = Trees.Thicket[T]
 
-    val EmptyTree: Thicket = genericEmptyTree
-    val EmptyValDef: ValDef = genericEmptyValDef
-    val EmptyModifiers: Modifiers = genericEmptyModifiers
+    @sharable val EmptyTree: Thicket = genericEmptyTree
+    @sharable val EmptyValDef: ValDef = genericEmptyValDef
+    @sharable val EmptyModifiers: Modifiers = genericEmptyModifiers
 
     // ----- Auxiliary creation methods ------------------
 

src/dotty/tools/dotc/config/Properties.scala

@@ -12,7 +12,7 @@ object Properties extends PropertiesTrait {
 
   /** Scala manifest attributes.
    */
-  val ScalaCompilerVersion = new AttributeName("Scala-Compiler-Version")
+  @sharable val ScalaCompilerVersion = new AttributeName("Scala-Compiler-Version")
 }
 
 trait PropertiesTrait {
@@ -23,7 +23,7 @@ trait PropertiesTrait {
   protected val propFilename = "/" + propCategory + ".properties"
 
   /** The loaded properties */
-  protected lazy val scalaProps: java.util.Properties = {
+  @sharable protected lazy val scalaProps: java.util.Properties = {
     val props = new java.util.Properties
     val stream = pickJarBasedOn getResourceAsStream propFilename
     if (stream ne null)

src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -151,6 +151,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val YnoDeepSubtypes = BooleanSetting("-Yno-deep-subtypes", "throw an exception on deep subtyping call stacks.")
   val YprintSyms = BooleanSetting("-Yprint-syms", "when printing trees print info in symbols instead of corresponding info in trees.")
   val YtestPickler = BooleanSetting("-Ytest-pickler", "self-test for pickling functionality; should be used with -Ystop-after:pickler")
+  val YcheckReentrant = BooleanSetting("-Ycheck-reentrant", "check that compiled program does not contain vars that can be accessed from a global root.")
   def stop = YstopAfter
 
   /** Area-specific debug output.

src/dotty/tools/dotc/config/ScalaVersion.scala

@@ -1,6 +1,7 @@
 /* @author  James Iry
  */
-package dotty.tools.dotc.config
+package dotty.tools
+package dotc.config
 
 import scala.util.{Try, Success, Failure}
 
@@ -15,7 +16,7 @@ sealed abstract class ScalaVersion extends Ordered[ScalaVersion] {
 /**
  * A scala version that sorts higher than all actual versions
  */
-case object NoScalaVersion extends ScalaVersion {
+@sharable case object NoScalaVersion extends ScalaVersion {
   def unparse = "none"
 
   def compare(that: ScalaVersion): Int = that match {
@@ -52,7 +53,7 @@ case class SpecificScalaVersion(major: Int, minor: Int, rev: Int, build: ScalaBu
 /**
  * A Scala version that sorts lower than all actual versions
  */
-case object AnyScalaVersion extends ScalaVersion {
+@sharable case object AnyScalaVersion extends ScalaVersion {
   def unparse = "any"
 
   def compare(that: ScalaVersion): Int = that match {
@@ -64,7 +65,7 @@ case object AnyScalaVersion extends ScalaVersion {
 /**
  * Methods for parsing ScalaVersions
  */
-object ScalaVersion {
+@sharable object ScalaVersion {
   private val dot = "\\."
   private val dash = "\\-"
   private def not(s:String) = s"[^${s}]"

src/dotty/tools/dotc/core/Contexts.scala

@@ -28,6 +28,7 @@ import printing._
 import config.{Settings, ScalaSettings, Platform, JavaPlatform}
 import language.implicitConversions
 import DenotTransformers.DenotTransformer
+
 object Contexts {
 
   /** A context is passed basically everywhere in dotc.
@@ -473,7 +474,7 @@ object Contexts {
     gadt = new GADTMap(SimpleMap.Empty)
   }
 
-  object NoContext extends Context {
+  @sharable object NoContext extends Context {
     lazy val base = unsupported("base")
     override val implicits: ContextualImplicits = new ContextualImplicits(Nil, null)(this)
   }
@@ -620,7 +621,7 @@ object Contexts {
     /** implicit conversion that injects all ContextBase members into a context */
     implicit def toBase(ctx: Context): ContextBase = ctx.base
 
-    val theBase = new ContextBase // !!! DEBUG, so that we can use a minimal context for reporting even in code that normally cannot access a context
+    // @sharable val theBase = new ContextBase // !!! DEBUG, so that we can use a minimal context for reporting even in code that normally cannot access a context
   }
 
   /** Info that changes on each compiler run */

src/dotty/tools/dotc/core/Denotations.scala

@@ -556,7 +556,7 @@ object Denotations {
      */
     private def bringForward()(implicit ctx: Context): SingleDenotation = this match {
       case denot: SymDenotation if ctx.stillValid(denot) =>
-        if (denot.exists) assert(ctx.runId > validFor.runId, s"denotation $denot invalid in run ${ctx.runId}. ValidFor: $validFor")
+        assert(ctx.runId > validFor.runId, s"denotation $denot invalid in run ${ctx.runId}. ValidFor: $validFor")
         var d: SingleDenotation = denot
         do {
           d.validFor = Period(ctx.period.runId, d.validFor.firstPhaseId, d.validFor.lastPhaseId)
@@ -592,7 +592,9 @@ object Denotations {
         assert(false)
       }
 
-      if (valid.runId != currentPeriod.runId) initial.bringForward.current
+      if (valid.runId != currentPeriod.runId)
+        if (exists) initial.bringForward.current
+        else this
       else {
         var cur = this
         if (currentPeriod.code > valid.code) {

src/dotty/tools/dotc/core/Flags.scala

@@ -136,7 +136,7 @@ object Flags {
   private final val FirstNotPickledFlag = 48
   private final val MaxFlag = 63
 
-  private var flagName = Array.fill(64, 2)("")
+  private val flagName = Array.fill(64, 2)("")
 
   private def isDefinedAsFlag(idx: Int) = flagName(idx) exists (_.nonEmpty)
 

src/dotty/tools/dotc/core/Names.scala

@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package core
 
 import scala.io.Codec
@@ -151,11 +152,13 @@ object Names {
     override def seq = toCollection(this)
   }
 
-  class TermName(val start: Int, val length: Int, private[Names] var next: TermName) extends Name {
+  class TermName(val start: Int, val length: Int, @sharable private[Names] var next: TermName) extends Name {
+    // `next` is @sharable because it is only modified in the synchronized block of termName.
     type ThisName = TermName
     def isTypeName = false
     def isTermName = true
 
+    @sharable // because it is only modified in the synchronized block of toTypeName.
     @volatile private[this] var _typeName: TypeName = null
 
     def toTypeName: TypeName = {
@@ -200,44 +203,21 @@ object Names {
   private final val fillFactor = 0.7
 
   /** Memory to store all names sequentially. */
+  @sharable // because it's only mutated in synchronized block of termName
   private[dotty] var chrs: Array[Char] = new Array[Char](InitialNameSize)
 
   /** The number of characters filled. */
+  @sharable // because it's only mutated in synchronized block of termName
   private var nc = 0
 
   /** Hashtable for finding term names quickly. */
+  @sharable // because it's only mutated in synchronized block of termName
   private var table = new Array[TermName](InitialHashSize)
 
   /** The number of defined names. */
+  @sharable // because it's only mutated in synchronized block of termName
   private var size = 1
 
-  /** Make sure the capacity of the character array is at least `n` */
-  private def ensureCapacity(n: Int) =
-    if (n > chrs.length) {
-      val newchrs = new Array[Char](chrs.length * 2)
-      chrs.copyToArray(newchrs)
-      chrs = newchrs
-    }
-
-  /** Make sure the hash table is large enough for the given load factor */
-  private def incTableSize() = {
-    size += 1
-    if (size.toDouble / table.size > fillFactor) {
-      val oldTable = table
-      table = new Array[TermName](table.size * 2)
-      for (i <- 0 until oldTable.size) rehash(oldTable(i))
-    }
-  }
-
-  /** Rehash chain of names */
-  private def rehash(name: TermName): Unit =
-    if (name != null) {
-      rehash(name.next)
-      val h = hashValue(chrs, name.start, name.length) & (table.size - 1)
-      name.next = table(h)
-      table(h) = name
-    }
-
   /** The hash of a name made of from characters cs[offset..offset+len-1].  */
   private def hashValue(cs: Array[Char], offset: Int, len: Int): Int =
     if (len > 0)
@@ -257,24 +237,53 @@ object Names {
     i == len
   }
 
-  /** Enter characters into chrs array. */
-  private def enterChars(cs: Array[Char], offset: Int, len: Int): Unit = {
-    ensureCapacity(nc + len)
-    var i = 0
-    while (i < len) {
-      chrs(nc + i) = cs(offset + i)
-      i += 1
-    }
-    nc += len
-  }
-
   /** Create a term name from the characters in cs[offset..offset+len-1].
    *  Assume they are already encoded.
    */
   def termName(cs: Array[Char], offset: Int, len: Int): TermName = {
     util.Stats.record("termName")
     val h = hashValue(cs, offset, len) & (table.size - 1)
+
     synchronized {
+
+      /** Make sure the capacity of the character array is at least `n` */
+      def ensureCapacity(n: Int) =
+        if (n > chrs.length) {
+          val newchrs = new Array[Char](chrs.length * 2)
+          chrs.copyToArray(newchrs)
+          chrs = newchrs
+        }
+
+      /** Enter characters into chrs array. */
+      def enterChars(): Unit = {
+        ensureCapacity(nc + len)
+        var i = 0
+        while (i < len) {
+          chrs(nc + i) = cs(offset + i)
+          i += 1
+        }
+        nc += len
+      }
+
+      /** Rehash chain of names */
+      def rehash(name: TermName): Unit =
+        if (name != null) {
+          rehash(name.next)
+          val h = hashValue(chrs, name.start, name.length) & (table.size - 1)
+          name.next = table(h)
+          table(h) = name
+        }
+
+      /** Make sure the hash table is large enough for the given load factor */
+      def incTableSize() = {
+        size += 1
+        if (size.toDouble / table.size > fillFactor) {
+          val oldTable = table
+          table = new Array[TermName](table.size * 2)
+          for (i <- 0 until oldTable.size) rehash(oldTable(i))
+        }
+      }
+
       val next = table(h)
       var name = next
       while (name ne null) {
@@ -283,7 +292,7 @@ object Names {
         name = name.next
       }
       name = new TermName(nc, len, next)
-      enterChars(cs, offset, len)
+      enterChars()
       table(h) = name
       incTableSize()
       name

src/dotty/tools/dotc/core/SymDenotations.scala

@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package core
 
 import Periods._, Contexts._, Symbols._, Denotations._, Names._, NameOps._, Annotations._
@@ -1713,8 +1714,8 @@ object SymDenotations {
     validFor = Period.allInRun(NoRunId) // will be brought forward automatically
   }
 
-  val NoDenotation = new NoDenotation
-  val NotDefinedHereDenotation = new NoDenotation
+  @sharable val NoDenotation = new NoDenotation
+  @sharable val NotDefinedHereDenotation = new NoDenotation
 
   // ---- Completion --------------------------------------------------------
 
@@ -1757,7 +1758,7 @@ object SymDenotations {
   val NoSymbolFn = (ctx: Context) => NoSymbol
 
   /** A missing completer */
-  class NoCompleter extends LazyType {
+  @sharable class NoCompleter extends LazyType {
     def complete(denot: SymDenotation)(implicit ctx: Context): Unit = unsupported("complete")
   }