Merge pull request #3136 from dotty-staging/leaner-ctx

Leaner Context objects

Author: smarter

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

@@ -263,6 +263,9 @@ object Contexts {
     final def withPhaseNoEarlier(phase: Phase) =
       if (phase.exists && ctx.phase.id < phase.id) withPhase(phase) else ctx
 
+    // `creationTrace`-related code. To enable, uncomment the code below and the
+    // call to `setCreationTrace()` in this file.
+    /*
     /** If -Ydebug is on, the top of the stack trace where this context
      *  was created, otherwise `null`.
      */
@@ -281,6 +284,7 @@ object Contexts {
       }
       println("=== end context creation trace ===")
     }
+    */
 
     /** The current reporter */
     def reporter: Reporter = typerState.reporter
@@ -414,7 +418,8 @@ object Contexts {
       this.implicitsCache = null
       this.phasedCtx = this
       this.phasedCtxs = null
-      setCreationTrace()
+      // See comment related to `creationTrace` in this file
+      // setCreationTrace()
       this
     }
 

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

@@ -76,16 +76,6 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
   private def isLegalPrefix(pre: Type)(implicit ctx: Context) =
     pre.isStable || !ctx.phase.isTyper
 
-  /** Approximate a type `tp` with a type that does not contain skolem types. */
-  object deskolemize extends ApproximatingTypeMap {
-    def apply(tp: Type) = /*ctx.traceIndented(i"deskolemize($tp) at $variance", show = true)*/ {
-      tp match {
-        case tp: SkolemType => range(tp.bottomType, atVariance(1)(apply(tp.info)))
-        case _ => mapOver(tp)
-      }
-    }
-  }
-
   /** Implementation of Types#simplified */
   final def simplify(tp: Type, theMap: SimplifyMap): Type = tp match {
     case tp: NamedType =>

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

@@ -1061,7 +1061,18 @@ class Namer { typer: Typer =>
 
       val rhsCtx = ctx.addMode(Mode.InferringReturnType)
       def rhsType = typedAheadExpr(mdef.rhs, inherited orElse rhsProto)(rhsCtx).tpe
-      def cookedRhsType = ctx.deskolemize(dealiasIfUnit(widenRhs(rhsType)))
+
+      // Approximate a type `tp` with a type that does not contain skolem types.
+      val deskolemize = new ApproximatingTypeMap {
+        def apply(tp: Type) = /*ctx.traceIndented(i"deskolemize($tp) at $variance", show = true)*/ {
+          tp match {
+            case tp: SkolemType => range(tp.bottomType, atVariance(1)(apply(tp.info)))
+            case _ => mapOver(tp)
+          }
+        }
+      }
+
+      def cookedRhsType = deskolemize(dealiasIfUnit(widenRhs(rhsType)))
       lazy val lhsType = fullyDefinedType(cookedRhsType, "right-hand side", mdef.pos)
       //if (sym.name.toString == "y") println(i"rhs = $rhsType, cooked = $cookedRhsType")
       if (inherited.exists)