Add @sharable annotation

Add @sharable annotation for classes and vals that are presumed
to be safely sharable between threads.

Also: Document CtxLazy.

4 files changed, 20 insertions, 15 deletions

diff --git a/src/dotty/tools/dotc/core/Contexts.scala b/src/dotty/tools/dotc/core/Contexts.scala
index c9deaab10..206ef9d8b 100644
--- a/src/dotty/tools/dotc/core/Contexts.scala
+++ b/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 */
diff --git a/src/dotty/tools/dotc/core/SymDenotations.scala b/src/dotty/tools/dotc/core/SymDenotations.scala
index 164b0b8f3..53973b587 100644
--- a/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/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")
   }
 
diff --git a/src/dotty/tools/dotc/core/TypeOps.scala b/src/dotty/tools/dotc/core/TypeOps.scala
index 2b2ef83a2..b61d39749 100644
--- a/src/dotty/tools/dotc/core/TypeOps.scala
+++ b/src/dotty/tools/dotc/core/TypeOps.scala
@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package core
 
 import Contexts._, Types._, Symbols._, Names._, Flags._, Scopes._
@@ -572,5 +573,5 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
 
 object TypeOps {
   val emptyDNF = (Nil, Set[Name]()) :: Nil
-  var track = false // !!!DEBUG
+  @sharable var track = false // !!!DEBUG
 }
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index d6bb9c3c5..85e2634d4 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package core
 
 import util.common._
@@ -35,7 +36,7 @@ import language.implicitConversions
 
 object Types {
 
-  private var nextId = 0
+  @sharable private var nextId = 0
 
   /** The class of types.
    *  The principal subclasses and sub-objects are as follows:
@@ -73,6 +74,7 @@ object Types {
 
 // ----- Tests -----------------------------------------------------
 
+    // debug only: a unique identifier for a type
     val uniqId = {
       nextId = nextId + 1
 //      if (nextId == 19555)
@@ -2752,13 +2754,13 @@ object Types {
   case class ImportType(expr: Tree) extends UncachedGroundType
 
   /** Sentinel for "missing type" */
-  case object NoType extends CachedGroundType {
+  @sharable case object NoType extends CachedGroundType {
     override def exists = false
     override def computeHash = hashSeed
   }
 
   /** Missing prefix */
-  case object NoPrefix extends CachedGroundType {
+  @sharable case object NoPrefix extends CachedGroundType {
     override def computeHash = hashSeed
   }
 
@@ -2775,7 +2777,7 @@ object Types {
 
   final class CachedWildcardType(optBounds: Type) extends WildcardType(optBounds)
 
-  object WildcardType extends WildcardType(NoType) {
+  @sharable object WildcardType extends WildcardType(NoType) {
     def apply(bounds: TypeBounds)(implicit ctx: Context) = unique(new CachedWildcardType(bounds))
   }
 
@@ -2983,7 +2985,7 @@ object Types {
     }
   }
 
-  object IdentityTypeMap extends TypeMap()(NoContext) {
+  @sharable object IdentityTypeMap extends TypeMap()(NoContext) {
     override def stopAtStatic = true
     def apply(tp: Type) = tp
   }
@@ -3208,7 +3210,7 @@ object Types {
 
   // ----- Debug ---------------------------------------------------------
 
-  var debugTrace = false
+  @sharable var debugTrace = false
 
   val watchList = List[String](
   ) map (_.toTypeName)