Merge pull request #1768 from dotty-staging/fix-#1765

Fix #1765: Context bounds and denotation handling

4 files changed, 35 insertions, 12 deletions

diff --git a/compiler/src/dotty/tools/dotc/ast/Desugar.scala b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
index 7f25d6b0c..15cb0b665 100644
--- a/compiler/src/dotty/tools/dotc/ast/Desugar.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
@@ -142,16 +142,21 @@ object desugar {
     val DefDef(name, tparams, vparamss, tpt, rhs) = meth
     val mods = meth.mods
     val epbuf = new ListBuffer[ValDef]
-    val tparams1 = tparams mapConserve {
-      case tparam @ TypeDef(_, ContextBounds(tbounds, cxbounds)) =>
+    def desugarContextBounds(rhs: Tree): Tree = rhs match {
+      case ContextBounds(tbounds, cxbounds) =>
         for (cxbound <- cxbounds) {
           val paramFlags: FlagSet = if (isPrimaryConstructor) PrivateLocalParamAccessor else Param
           val epname = ctx.freshName(nme.EVIDENCE_PARAM_PREFIX).toTermName
           epbuf += ValDef(epname, cxbound, EmptyTree).withFlags(paramFlags | Implicit)
         }
-        cpy.TypeDef(tparam)(rhs = tbounds)
-      case tparam =>
-        tparam
+        tbounds
+      case PolyTypeTree(tparams, body) =>
+        cpy.PolyTypeTree(rhs)(tparams, desugarContextBounds(body))
+      case _ =>
+        rhs
+    }
+    val tparams1 = tparams mapConserve { tdef =>
+      cpy.TypeDef(tdef)(rhs = desugarContextBounds(tdef.rhs))
     }
 
     val meth1 = addEvidenceParams(cpy.DefDef(meth)(tparams = tparams1), epbuf.toList)
diff --git a/compiler/src/dotty/tools/dotc/core/Denotations.scala b/compiler/src/dotty/tools/dotc/core/Denotations.scala
index 6a39c5787..99c688d50 100644
--- a/compiler/src/dotty/tools/dotc/core/Denotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/Denotations.scala
@@ -132,7 +132,7 @@ object Denotations {
     def atSignature(sig: Signature, site: Type = NoPrefix, relaxed: Boolean = false)(implicit ctx: Context): Denotation
 
     /** The variant of this denotation that's current in the given context.
-     *  If no such denotation exists, returns the denotation with each alternative 
+     *  If no such denotation exists, returns the denotation with each alternative
      *  at its first point of definition.
      */
     def current(implicit ctx: Context): Denotation
@@ -744,6 +744,20 @@ object Denotations {
         else NoDenotation
     }
 
+    /** The next defined denotation (following `nextInRun`) or an arbitrary
+     *  undefined denotation, if all denotations in a `nextinRun` cycle are
+     *  undefined.
+     */
+    private def nextDefined: SingleDenotation = {
+      var p1 = this
+      var p2 = nextInRun
+      while (p1.validFor == Nowhere && (p1 ne p2)) {
+        p1 = p1.nextInRun
+        p2 = p2.nextInRun.nextInRun
+      }
+      p1
+    }
+
     /** Produce a denotation that is valid for the given context.
      *  Usually called when !(validFor contains ctx.period)
      *  (even though this is not a precondition).
@@ -763,8 +777,9 @@ object Denotations {
         // can happen if we sit on a stale denotation which has been replaced
         // wholesale by an installAfter; in this case, proceed to the next
         // denotation and try again.
-        if (validFor == Nowhere && nextInRun.validFor != Nowhere) return nextInRun.current
-        assert(false)
+        val nxt = nextDefined
+        if (nxt.validFor != Nowhere) return nxt
+        assert(false, this)
       }
 
       if (valid.runId != currentPeriod.runId)
@@ -905,6 +920,7 @@ object Denotations {
       prev.nextInRun = this
       this.nextInRun = old.nextInRun
       old.validFor = Nowhere
+      old.nextInRun = this
     }
 
     def staleSymbolError(implicit ctx: Context) = {
diff --git a/compiler/src/dotty/tools/dotc/core/Periods.scala b/compiler/src/dotty/tools/dotc/core/Periods.scala
index 6efadab7f..29d9d208f 100644
--- a/compiler/src/dotty/tools/dotc/core/Periods.scala
+++ b/compiler/src/dotty/tools/dotc/core/Periods.scala
@@ -153,7 +153,7 @@ object Periods {
   final val FirstPhaseId = 1
 
   /** The number of bits needed to encode a phase identifier. */
-  final val PhaseWidth = 6
+  final val PhaseWidth = 7
   final val PhaseMask = (1 << PhaseWidth) - 1
   final val MaxPossiblePhaseId = PhaseMask
 }
diff --git a/compiler/src/dotty/tools/dotc/transform/Memoize.scala b/compiler/src/dotty/tools/dotc/transform/Memoize.scala
index 01c240e3a..0314d4ec4 100644
--- a/compiler/src/dotty/tools/dotc/transform/Memoize.scala
+++ b/compiler/src/dotty/tools/dotc/transform/Memoize.scala
@@ -47,7 +47,9 @@ import Decorators._
     }
     tree match {
       case ddef: DefDef
-        if !ddef.symbol.is(Deferred) && ddef.rhs == EmptyTree =>
+        if !ddef.symbol.is(Deferred) &&
+           !ddef.symbol.isConstructor && // constructors bodies are added later at phase Constructors
+           ddef.rhs == EmptyTree =>
           errorLackImplementation(ddef)
       case tdef: TypeDef
         if tdef.symbol.isClass && !tdef.symbol.is(Deferred) && tdef.rhs == EmptyTree =>
@@ -89,10 +91,10 @@ import Decorators._
     }
 
     lazy val field = sym.field.orElse(newField).asTerm
-    
+
     def adaptToField(tree: Tree) =
       if (tree.isEmpty) tree else tree.ensureConforms(field.info.widen)
-      
+
     if (sym.is(Accessor, butNot = NoFieldNeeded))
       if (sym.isGetter) {
         def skipBlocks(t: Tree): Tree = t match {