Generalize symbolic refs

Previously, there was a switch in SymDenotation#termRef to create a WithFixedSym ref
when after erasure. This was done to fix a broken test, but it's clearly incomplete.
The scheme is now replaced by one which always creates WithFixedSym Termrefs after
erasure.

Author: odersky

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

@@ -896,9 +896,8 @@ object SymDenotations {
     override def valRef(implicit ctx: Context): TermRef =
       TermRef.withSigAndDenot(owner.thisType, name.asTermName, Signature.NotAMethod, this)
 
-    override def termRefWithSig(implicit ctx: Context): TermRef = // TODO generalize
-      if (ctx.erasedTypes) TermRef.withFixedSym(owner.thisType, name.asTermName, symbol.asTerm)
-      else TermRef.withSigAndDenot(owner.thisType, name.asTermName, signature, this)
+    override def termRefWithSig(implicit ctx: Context): TermRef =
+      TermRef.withSigAndDenot(owner.thisType, name.asTermName, signature, this)
 
     def nonMemberTermRef(implicit ctx: Context): TermRef =
       TermRef.withFixedSym(owner.thisType, name.asTermName, symbol.asTerm)

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

@@ -1183,7 +1183,7 @@ object Types {
             // That's why the branch is disabled.
             //
             //   else if (ctx.erasedTypes && lastSymbol != null)
-            //   denotOfSym(lastSymbol) 
+            //   denotOfSym(lastSymbol)
             else
               d.current
         }
@@ -1516,7 +1516,7 @@ object Types {
      *  signature, if denotation is not yet completed.
      */
     def apply(prefix: Type, name: TermName, denot: Denotation)(implicit ctx: Context): TermRef = {
-      if ((prefix eq NoPrefix) || denot.symbol.isFresh)
+      if ((prefix eq NoPrefix) || denot.symbol.isFresh || ctx.erasedTypes)
         apply(prefix, denot.symbol.asTerm)
       else denot match {
         case denot: SymDenotation if denot.isCompleted => withSig(prefix, name, denot.signature)
@@ -1538,7 +1538,7 @@ object Types {
      *  (2) The name in the term ref need not be the same as the name of the Symbol.
      */
     def withSymAndName(prefix: Type, sym: TermSymbol, name: TermName)(implicit ctx: Context): TermRef =
-      if ((prefix eq NoPrefix) || sym.isFresh)
+      if ((prefix eq NoPrefix) || sym.isFresh || ctx.erasedTypes)
         withFixedSym(prefix, name, sym)
       else if (sym.defRunId != NoRunId && sym.isCompleted)
         withSig(prefix, name, sym.signature) withSym (sym, sym.signature)
@@ -1549,7 +1549,7 @@ object Types {
      *  (which must be completed).
      */
     def withSig(prefix: Type, sym: TermSymbol)(implicit ctx: Context): TermRef =
-      if ((prefix eq NoPrefix) || sym.isFresh) withFixedSym(prefix, sym.name, sym)
+      if ((prefix eq NoPrefix) || sym.isFresh || ctx.erasedTypes) withFixedSym(prefix, sym.name, sym)
       else withSig(prefix, sym.name, sym.signature).withSym(sym, sym.signature)
 
     /** Create a term ref with given prefix, name and signature */
@@ -1558,7 +1558,7 @@ object Types {
 
     /** Create a term ref with given prefix, name, signature, and initial denotation */
     def withSigAndDenot(prefix: Type, name: TermName, sig: Signature, denot: Denotation)(implicit ctx: Context): TermRef = {
-      if ((prefix eq NoPrefix) || denot.symbol.isFresh)
+      if ((prefix eq NoPrefix) || denot.symbol.isFresh || ctx.erasedTypes)
         withFixedSym(prefix, denot.symbol.asTerm.name, denot.symbol.asTerm)
       else
         withSig(prefix, name, sig)