Add showDcl method for SingleDenotations

Author: odersky

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

@@ -619,7 +619,7 @@ object Denotations {
       throw new StaleSymbol(msg)
     }
 
-    /** The period (interval of phases) for which there exists 
+    /** The period (interval of phases) for which there exists
      *  a valid denotation in this flock.
      */
     def coveredInterval(implicit ctx: Context): Period = {
@@ -641,11 +641,15 @@ object Denotations {
      */
     def syncWithParents(implicit ctx: Context): SingleDenotation = this
 
+    /** Show declaration string; useful for showing declarations
+     *  as seen from subclasses.
+     */
+    def showDcl(implicit ctx: Context): String = ctx.dclText(this).show
+
     override def toString =
       if (symbol == NoSymbol) symbol.toString
       else s"<SingleDenotation of type $infoOrCompleter>"
 
-
     def definedPeriodsString: String = {
       var sb = new StringBuilder()
       var cur = this

src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -2,7 +2,7 @@ package dotty.tools.dotc
 package printing
 
 import core._
-import Texts._, Types._, Flags._, Names._, Symbols._, NameOps._, Constants._
+import Texts._, Types._, Flags._, Names._, Symbols._, NameOps._, Constants._, Denotations._
 import Contexts.Context, Scopes.Scope, Denotations.Denotation, Annotations.Annotation
 import StdNames.nme
 import ast.Trees._, ast.untpd
@@ -321,9 +321,13 @@ class PlainPrinter(_ctx: Context) extends Printer {
 
   def annotsText(sym: Symbol): Text = Text(sym.annotations.map(toText))
 
-  def dclText(sym: Symbol): Text =
+  def dclText(sym: Symbol): Text = dclTextWithInfo(sym, sym.unforcedInfo)
+
+  def dclText(d: SingleDenotation): Text = dclTextWithInfo(d.symbol, Some(d.info))
+
+  private def dclTextWithInfo(sym: Symbol, info: Option[Type]): Text =
     (toTextFlags(sym) ~~ keyString(sym) ~~
-      (varianceString(sym) ~ nameString(sym)) ~ toTextRHS(sym.unforcedInfo)).close
+      (varianceString(sym) ~ nameString(sym)) ~ toTextRHS(info)).close
 
   def toText(sym: Symbol): Text =
     (kindString(sym) ~~ {

src/dotty/tools/dotc/printing/Printer.scala

@@ -4,7 +4,7 @@ package printing
 import core._
 import Texts._, ast.Trees._
 import Types.Type, Symbols.Symbol, Contexts.Context, Scopes.Scope, Constants.Constant,
-       Names.Name, Denotations.Denotation, Annotations.Annotation
+       Names.Name, Denotations._, Annotations.Annotation
 
 /** The base class of all printers
  */
@@ -59,6 +59,9 @@ abstract class Printer {
   /** Textual representation of symbol's declaration */
   def dclText(sym: Symbol): Text
 
+  /** Textual representation of single denotation's declaration */
+  def dclText(sd: SingleDenotation): Text
+
   /** If symbol's owner is a printable class C, the text "in C", otherwise "" */
   def locationText(sym: Symbol): Text