Implement SearchResult.show

Author: odersky

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

@@ -6,6 +6,7 @@ import Texts._, Types._, Flags._, Names._, Symbols._, NameOps._, Constants._, De
 import Contexts.Context, Scopes.Scope, Denotations.Denotation, Annotations.Annotation
 import StdNames.{nme, tpnme}
 import ast.Trees._, ast._
+import typer.Implicits._
 import config.Config
 import java.lang.Integer.toOctalString
 import config.Config.summarizeDepth
@@ -484,6 +485,23 @@ class PlainPrinter(_ctx: Context) extends Printer {
     }
   }.close // todo: override in refined printer
 
+  def toText(result: SearchResult): Text = result match {
+    case result: SearchSuccess =>
+      "SearchSuccess: " ~ toText(result.ref) ~ " via " ~ toText(result.tree)
+    case result: NonMatchingImplicit =>
+      "NoImplicitMatches"
+    case result: DivergingImplicit =>
+      "Diverging Implicit"
+    case result: ShadowedImplicit =>
+      "Shadowed Implicit"
+    case result: FailedImplicit =>
+      "Failed Implicit"
+    case result: AmbiguousImplicits =>
+      "Ambiguous Implicit: " ~ toText(result.alt1) ~ " and " ~ toText(result.alt2)
+    case _ =>
+      "?Unknown Implicit Result?"
+  }
+
   private var maxSummarized = Int.MaxValue
 
   def summarized[T](depth: Int)(op: => T): T = {

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

@@ -5,6 +5,7 @@ import core._
 import Texts._, ast.Trees._
 import Types.Type, Symbols.Symbol, Contexts.Context, Scopes.Scope, Constants.Constant,
        Names.Name, Denotations._, Annotations.Annotation
+import typer.Implicits.SearchResult
 
 /** The base class of all printers
  */
@@ -94,7 +95,10 @@ abstract class Printer {
   /** Textual representation of tree */
   def toText[T >: Untyped](tree: Tree[T]): Text
 
-  /** Perform string or text-producing operation `op` so that only a
+  /** Textual representation of implicit search result */
+  def toText(result: SearchResult): Text
+
+      /** Perform string or text-producing operation `op` so that only a
    *  summarized text with given recursion depth is shown
    */
   def summarized[T](depth: Int)(op: => T): T

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

@@ -6,7 +6,8 @@ import core._
 import ast.{Trees, untpd, tpd, TreeInfo}
 import util.Positions._
 import util.Stats.{track, record, monitored}
-import printing.Showable
+import printing.{Showable, Printer}
+import printing.Texts._
 import Contexts._
 import Types._
 import Flags._
@@ -219,14 +220,16 @@ object Implicits {
   }
 
   /** The result of an implicit search */
-  abstract class SearchResult
+  abstract class SearchResult extends Showable {
+    def toText(printer: Printer): Text = printer.toText(this)
+  }
 
   /** A successful search
    *  @param ref   The implicit reference that succeeded
    *  @param tree  The typed tree that needs to be inserted
    *  @param ctx   The context after the implicit search
    */
-  case class SearchSuccess(tree: tpd.Tree, ref: TermRef, level: Int, tstate: TyperState) extends SearchResult {
+  case class SearchSuccess(tree: tpd.Tree, ref: TermRef, level: Int, tstate: TyperState) extends SearchResult with Showable {
     override def toString = s"SearchSuccess($tree, $ref, $level)"
   }
 
@@ -256,7 +259,7 @@ object Implicits {
   }
 
   /** An ambiguous implicits failure */
-  class AmbiguousImplicits(alt1: TermRef, alt2: TermRef, val pt: Type, val argument: tpd.Tree) extends ExplainedSearchFailure {
+  class AmbiguousImplicits(val alt1: TermRef, val alt2: TermRef, val pt: Type, val argument: tpd.Tree) extends ExplainedSearchFailure {
     def explanation(implicit ctx: Context): String =
       em"both ${err.refStr(alt1)} and ${err.refStr(alt2)} $qualify"
     override def postscript(implicit ctx: Context) =
@@ -604,6 +607,7 @@ trait Implicits { self: Typer =>
       result match {
         case result: SearchSuccess =>
           result.tstate.commit()
+          implicits.println(i"committing ${result.tstate.constraint} yielding ${ctx.typerState.constraint} ${ctx.typerState.hashesStr}")
           result
         case result: AmbiguousImplicits =>
           val deepPt = pt.deepenProto