From 281dbb553b20ca16dd9e749acdfe39129e20fa28 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Wed, 14 Sep 2016 17:52:11 +0200
Subject: [PATCH 01/53] Add initial structure for improved explanations of
 error messages

---
 .../tools/dotc/config/ScalaSettings.scala     |  1 +
 src/dotty/tools/dotc/parsing/Parsers.scala    | 23 +++----
 src/dotty/tools/dotc/reporting/Examples.scala | 67 +++++++++++++++++++
 src/dotty/tools/dotc/reporting/Reporter.scala | 13 ++++
 4 files changed, 91 insertions(+), 13 deletions(-)
 create mode 100644 src/dotty/tools/dotc/reporting/Examples.scala

diff --git a/src/dotty/tools/dotc/config/ScalaSettings.scala b/src/dotty/tools/dotc/config/ScalaSettings.scala
index ff17a993991a..a4daefcba200 100644
--- a/src/dotty/tools/dotc/config/ScalaSettings.scala
+++ b/src/dotty/tools/dotc/config/ScalaSettings.scala
@@ -23,6 +23,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val migration = BooleanSetting("-migration", "Emit warning and location for migration issues from Scala 2.")
   val encoding = StringSetting("-encoding", "encoding", "Specify character encoding used by source files.", Properties.sourceEncoding)
   val explaintypes = BooleanSetting("-explaintypes", "Explain type errors in more detail.")
+  val explainerrors = BooleanSetting("-explain", "Explain errors in more detail.")
   val feature = BooleanSetting("-feature", "Emit warning and location for usages of features that should be imported explicitly.")
   val g = ChoiceSetting("-g", "level", "Set level of generated debugging info.", List("none", "source", "line", "vars", "notailcalls"), "vars")
   val help = BooleanSetting("-help", "Print a synopsis of standard options")
diff --git a/src/dotty/tools/dotc/parsing/Parsers.scala b/src/dotty/tools/dotc/parsing/Parsers.scala
index 9aadf0c616ae..e4378d82b108 100644
--- a/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -17,6 +17,7 @@ import ast.Trees._
 import Decorators._
 import StdNames._
 import util.Positions._
+import reporting.ErrorExplanations._
 import Constants._
 import ScriptParsers._
 import Comments._
@@ -97,17 +98,17 @@ object Parsers {
     /** Issue an error at given offset if beyond last error offset
       *  and update lastErrorOffset.
       */
-    def syntaxError(msg: String, offset: Int = in.offset): Unit =
+    def syntaxError(expl: Explanation, offset: Int = in.offset): Unit =
       if (offset > lastErrorOffset) {
-        syntaxError(msg, Position(offset))
+        syntaxError(expl, Position(offset))
         lastErrorOffset = in.offset
       }
 
     /** Unconditionally issue an error at given position, without
       *  updating lastErrorOffset.
       */
-    def syntaxError(msg: String, pos: Position): Unit =
-      ctx.error(msg, source atPos pos)
+    def syntaxError(expl: Explanation, pos: Position): Unit =
+      ctx.explainError(expl, source atPos pos)
 
   }
 
@@ -213,8 +214,8 @@ object Parsers {
       }
     }
 
-    def warning(msg: String, offset: Int = in.offset) =
-      ctx.warning(msg, source atPos Position(offset))
+    def warning(msg: Explanation, offset: Int = in.offset) =
+      ctx.explainWarning(msg, source atPos Position(offset))
 
     def deprecationWarning(msg: String, offset: Int = in.offset) =
       ctx.deprecationWarning(msg, source atPos Position(offset))
@@ -1013,19 +1014,15 @@ object Parsers {
             } else EmptyTree
 
           handler match {
-            case Block(Nil, EmptyTree) => syntaxError(
-              "`catch` block does not contain a valid expression, try adding a case like - `case e: Exception =>` to the block",
-              handler.pos
-            )
+            case Block(Nil, EmptyTree) =>
+              syntaxError(EmptyCatchBlock(body), handler.pos)
             case _ =>
           }
 
           val finalizer =
             if (in.token == FINALLY) { accept(FINALLY); expr() }
             else {
-              if (handler.isEmpty)
-                warning("A try without `catch` or `finally` is equivalent to putting its body in a block; no exceptions are handled.")
-
+              if (handler.isEmpty) warning(EmptyCatchAndFinallyBlock(body))
               EmptyTree
             }
           ParsedTry(body, handler, finalizer)
diff --git a/src/dotty/tools/dotc/reporting/Examples.scala b/src/dotty/tools/dotc/reporting/Examples.scala
new file mode 100644
index 000000000000..d2dbd70eb347
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/Examples.scala
@@ -0,0 +1,67 @@
+package dotty.tools
+package dotc
+package reporting
+
+import dotc.core.Contexts.Context
+
+object ErrorExplanations {
+  import dotc.ast.Trees._
+  import dotc.ast.untpd
+
+  implicit def stringToExplanation(s: String) = NoExplanation(s)
+
+  implicit class ShouldExplainCtx(val c: Context) extends AnyVal {
+    def shouldExplain(expl: Explanation): Boolean = {
+      implicit val ctx = c
+      expl match {
+        case _: NoExplanation => false
+        case expl if ctx.settings.explainerrors.value => true
+        case _ => false
+      }
+    }
+  }
+
+  trait Explanation {
+    def msg: String
+    def explanation: String
+  }
+
+  case class NoExplanation(msg: String) extends Explanation {
+    val explanation = ""
+  }
+
+  abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends Explanation {
+    val explanation = {
+      val tryString = tryBody match {
+        case Block(Nil, untpd.EmptyTree) => "{}"
+        case _ => tryBody.show
+      }
+      s"""|Explanation:
+          |============
+          |A try expression should be followed by some mechanism to handle any exceptions
+          |thrown. Typically a `catch` expression follows the `try` and pattern matches
+          |on any expected exceptions. For example:
+          |
+          |try $tryString catch {
+          | case t: Throwable => ???
+          |}
+          |
+          |It is also possible to follow a `try` immediately by a finally - letting the
+          |exception propagate - but still allowing for some clean up in `finally`:
+          |
+          |try $tryString finally {
+          | // perform your cleanup here!
+          |}""".stripMargin
+    }
+  }
+
+  case class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends EmptyCatchOrFinallyBlock(tryBody) {
+    val msg =
+      "`catch` block does not contain a valid expression, try adding a case like - `case e: Exception =>` to the block"
+  }
+
+  case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends EmptyCatchOrFinallyBlock(tryBody) {
+    val msg =
+      "A try without `catch` or `finally` is equivalent to putting its body in a block; no exceptions are handled."
+  }
+}
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index 75113d823880..eb9a10a59739 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -13,6 +13,7 @@ import java.lang.System.currentTimeMillis
 import core.Mode
 import interfaces.Diagnostic.{ERROR, WARNING, INFO}
 import dotty.tools.dotc.core.Symbols.Symbol
+import ErrorExplanations._
 
 object Reporter {
   class Error(msgFn: => String, pos: SourcePosition) extends Diagnostic(msgFn, pos, ERROR)
@@ -95,6 +96,12 @@ trait Reporting { this: Context =>
   def warning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(new Warning(msg, pos))
 
+  def explainWarning(expl: => Explanation, pos: SourcePosition = NoSourcePosition): Unit = {
+    warning(expl.msg, pos)
+    if (this.shouldExplain(expl))
+      reporter.report(new Info(expl.explanation, NoSourcePosition))
+  }
+
   def strictWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     if (this.settings.strict.value) error(msg, pos)
     else warning(msg + "\n(This would be an error under strict mode)", pos)
@@ -104,6 +111,12 @@ trait Reporting { this: Context =>
     reporter.report(new Error(msg, pos))
   }
 
+  def explainError(expl: => Explanation, pos: SourcePosition = NoSourcePosition): Unit = {
+    error(expl.msg, pos)
+    if (this.shouldExplain(expl))
+      reporter.report(new Info(expl.explanation, NoSourcePosition))
+  }
+
   def errorOrMigrationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     if (ctx.scala2Mode) migrationWarning(msg, pos) else error(msg, pos)
 

From a6997587fec8e73f28ca3145339ee971aeaa94b2 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 11:51:02 +0200
Subject: [PATCH 02/53] Add highlighter string interpolator

---
 .../tools/dotc/printing/SyntaxHighlighting.scala | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 83c4289765a2..932b980dba31 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -5,9 +5,25 @@ package printing
 import parsing.Tokens._
 import scala.annotation.switch
 import scala.collection.mutable.StringBuilder
+import core.Contexts.Context
 
 /** This object provides functions for syntax highlighting in the REPL */
 object SyntaxHighlighting {
+
+  implicit class SyntaxFormatting(val sc: StringContext) extends AnyVal {
+    def hl(args: Any*)(implicit ctx: Context): String =
+      new SyntaxFormatter(sc).assemble(args)
+  }
+
+  private class SyntaxFormatter(sc: StringContext) extends Formatting.StringFormatter(sc) {
+    override def assemble(args: Seq[Any])(implicit ctx: Context): String = super.assemble {
+      args.map {
+        case str: String => new String(apply(str).toArray)
+        case x => x
+      }
+    }
+  }
+
   val NoColor         = Console.RESET
   val CommentColor    = Console.GREEN
   val KeywordColor    = Console.CYAN

From d2c9e190070a87f75f5398c90758134269752a90 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 11:51:40 +0200
Subject: [PATCH 03/53] Return iterable from highlighting function instead of
 vector

---
 src/dotty/tools/dotc/printing/SyntaxHighlighting.scala | 4 ++--
 src/dotty/tools/dotc/repl/AmmoniteReader.scala         | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 932b980dba31..c933dd0b9763 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -51,7 +51,7 @@ object SyntaxHighlighting {
   private val typeEnders =
    '{' :: '}' :: ')' :: '(' :: '=' :: ' ' :: ',' :: '.' :: '\n' :: Nil
 
-  def apply(chars: Iterable[Char]): Vector[Char] = {
+  def apply(chars: Iterable[Char]): Iterable[Char] = {
     var prev: Char = 0
     var remaining  = chars.toStream
     val newBuf     = new StringBuilder
@@ -281,6 +281,6 @@ object SyntaxHighlighting {
       prev = curr
     }
 
-    newBuf.toVector
+    newBuf.toIterable
   }
 }
diff --git a/src/dotty/tools/dotc/repl/AmmoniteReader.scala b/src/dotty/tools/dotc/repl/AmmoniteReader.scala
index 614654a28b78..435269081dde 100644
--- a/src/dotty/tools/dotc/repl/AmmoniteReader.scala
+++ b/src/dotty/tools/dotc/repl/AmmoniteReader.scala
@@ -61,7 +61,7 @@ class AmmoniteReader(val interpreter: Interpreter)(implicit ctx: Context) extend
           if (ctx.useColors) SyntaxHighlighting(buffer)
           else buffer
 
-        val ansiBuffer = Ansi.Str.parse(coloredBuffer)
+        val ansiBuffer = Ansi.Str.parse(coloredBuffer.toVector)
         val (newBuffer, cursorOffset) = SelectionFilter.mangleBuffer(
           selectionFilter, ansiBuffer, cursor, Ansi.Reversed.On
         )

From 6495210d685fcf89e8ee453e8999ee8883f20683 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 11:52:22 +0200
Subject: [PATCH 04/53] Add highlighting for `???`

---
 src/dotty/tools/dotc/printing/SyntaxHighlighting.scala | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index c933dd0b9763..51dee349ba4e 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -36,6 +36,7 @@ object SyntaxHighlighting {
   private def typeDef(str: String)    = TypeColor + str + NoColor
   private def literal(str: String)    = LiteralColor + str + NoColor
   private def annotation(str: String) = AnnotationColor + str + NoColor
+  private val tripleQs = Console.RED_B + "???" + NoColor
 
   private val keywords: Seq[String] = for {
     index <- IF to INLINE // All alpha keywords
@@ -123,7 +124,11 @@ object SyntaxHighlighting {
           case '`'  =>
             appendTo('`', _ == '`', none)
           case _    => {
-            if (n.isUpper && keywordStart)
+            if (n == '?' && remaining.take(2).mkString == "??") {
+              takeChars(2)
+              newBuf append tripleQs
+              prev = '?'
+            } else if (n.isUpper && keywordStart)
               appendWhile(n, !typeEnders.contains(_), typeDef)
             else if (numberStart(n))
               appendWhile(n, { x => x.isDigit || x == '.' || x == '\u0000'}, literal)

From e4a7db12c2e24b668f146c75469c1e61b7455456 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 15:38:40 +0200
Subject: [PATCH 05/53] Simplify "hl" interpolator

---
 .../tools/dotc/printing/SyntaxHighlighting.scala    | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 51dee349ba4e..6c7e65a0bfb6 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -11,17 +11,8 @@ import core.Contexts.Context
 object SyntaxHighlighting {
 
   implicit class SyntaxFormatting(val sc: StringContext) extends AnyVal {
-    def hl(args: Any*)(implicit ctx: Context): String =
-      new SyntaxFormatter(sc).assemble(args)
-  }
-
-  private class SyntaxFormatter(sc: StringContext) extends Formatting.StringFormatter(sc) {
-    override def assemble(args: Seq[Any])(implicit ctx: Context): String = super.assemble {
-      args.map {
-        case str: String => new String(apply(str).toArray)
-        case x => x
-      }
-    }
+    def hl(args: Any*): String =
+      sc.s(args.map(x => new String(apply(x.toString).toArray)): _*)
   }
 
   val NoColor         = Console.RESET

From 66f7f7d23264374f9fbc581538fa1f47de16433c Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 15:39:12 +0200
Subject: [PATCH 06/53] Use highlighting in explanation classes

---
 src/dotty/tools/dotc/reporting/Examples.scala | 45 +++++++++++--------
 1 file changed, 27 insertions(+), 18 deletions(-)

diff --git a/src/dotty/tools/dotc/reporting/Examples.scala b/src/dotty/tools/dotc/reporting/Examples.scala
index d2dbd70eb347..9759d39e8cec 100644
--- a/src/dotty/tools/dotc/reporting/Examples.scala
+++ b/src/dotty/tools/dotc/reporting/Examples.scala
@@ -3,6 +3,7 @@ package dotc
 package reporting
 
 import dotc.core.Contexts.Context
+import dotc.printing.SyntaxHighlighting._
 
 object ErrorExplanations {
   import dotc.ast.Trees._
@@ -36,32 +37,40 @@ object ErrorExplanations {
         case Block(Nil, untpd.EmptyTree) => "{}"
         case _ => tryBody.show
       }
-      s"""|Explanation:
-          |============
-          |A try expression should be followed by some mechanism to handle any exceptions
-          |thrown. Typically a `catch` expression follows the `try` and pattern matches
-          |on any expected exceptions. For example:
-          |
-          |try $tryString catch {
-          | case t: Throwable => ???
-          |}
-          |
-          |It is also possible to follow a `try` immediately by a finally - letting the
-          |exception propagate - but still allowing for some clean up in `finally`:
-          |
-          |try $tryString finally {
-          | // perform your cleanup here!
-          |}""".stripMargin
+
+      val code1 =
+        s"""|try $tryString catch {
+            |  case t: Throwable => ???
+            |}""".stripMargin
+
+      val code2 =
+        s"""|try $tryString finally {
+            |  // perform your cleanup here!
+            |}""".stripMargin
+
+      hl"""|Explanation:
+           |============
+           |A ${"try"} expression should be followed by some mechanism to handle any exceptions
+           |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
+           |on any expected exceptions. For example:
+           |
+           |$code1
+           |
+           |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
+           |exception propagate - but still allowing for some clean up in ${"finally"}:
+           |
+           |$code2
+           """.stripMargin
     }
   }
 
   case class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends EmptyCatchOrFinallyBlock(tryBody) {
     val msg =
-      "`catch` block does not contain a valid expression, try adding a case like - `case e: Exception =>` to the block"
+      hl"""The ${"catch"} block does not contain a valid expression, try adding a case like - `${"case e: Exception =>"}` to the block"""
   }
 
   case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends EmptyCatchOrFinallyBlock(tryBody) {
     val msg =
-      "A try without `catch` or `finally` is equivalent to putting its body in a block; no exceptions are handled."
+      hl"""A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting its body in a block; no exceptions are handled."""
   }
 }

From c9a8bb8d783d288ae2c165b8eefb3ca47c372c4e Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 18:04:03 +0200
Subject: [PATCH 07/53] Add more examples to Typer

---
 src/dotty/tools/dotc/reporting/Examples.scala | 32 ++++++++++++++++++-
 src/dotty/tools/dotc/typer/Typer.scala        | 24 ++++++++------
 2 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/src/dotty/tools/dotc/reporting/Examples.scala b/src/dotty/tools/dotc/reporting/Examples.scala
index 9759d39e8cec..652620e2991b 100644
--- a/src/dotty/tools/dotc/reporting/Examples.scala
+++ b/src/dotty/tools/dotc/reporting/Examples.scala
@@ -2,8 +2,10 @@ package dotty.tools
 package dotc
 package reporting
 
-import dotc.core.Contexts.Context
+import dotc.core._
+import Contexts.Context, Decorators._, Symbols._
 import dotc.printing.SyntaxHighlighting._
+import util.{SourcePosition, NoSourcePosition}
 
 object ErrorExplanations {
   import dotc.ast.Trees._
@@ -73,4 +75,32 @@ object ErrorExplanations {
     val msg =
       hl"""A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting its body in a block; no exceptions are handled."""
   }
+
+  case class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context) extends Explanation {
+    val msg =
+      em"duplicate pattern variable: `${bind.name}`"
+
+    val explanation = {
+      val pat = tree.pat.show
+      val guard = tree.guard match {
+        case untpd.EmptyTree => ""
+        case guard => s"if ${guard.show}"
+      }
+
+      val body = tree.body match {
+        case Block(Nil, untpd.EmptyTree) => ""
+        case body => s" ${body.show}"
+      }
+
+      val caseDef = s"case $pat$guard => $body"
+
+      hl"""|Explanation
+           |===========
+           |For each ${"case"} bound variable names  have to be unique. In:
+           |
+           |$caseDef
+           |
+           |`${bind.name}` is not unique. Rename one of the binds!""".stripMargin
+    }
+  }
 }
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 3e3bb32f5571..19297f9ec29c 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -37,6 +37,8 @@ import rewrite.Rewrites.patch
 import NavigateAST._
 import transform.SymUtils._
 import language.implicitConversions
+import printing.SyntaxHighlighting._
+import reporting.ErrorExplanations._
 
 object Typer {
 
@@ -141,9 +143,11 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
        *      imported by <tree>
        *  or  defined in <symbol>
        */
-      def bindingString(prec: Int, whereFound: Context, qualifier: String = "")(implicit ctx: Context) =
-        if (prec == wildImport || prec == namedImport) ex"imported$qualifier by ${whereFound.importInfo}"
-        else ex"defined$qualifier in ${whereFound.owner}"
+      def bindingString(prec: Int, whereFound: Context, qualifier: String = "") =
+        if (prec == wildImport || prec == namedImport) {
+          ex"""imported$qualifier by ${hl"${whereFound.importInfo.toString}"}"""
+        } else
+          ex"""defined$qualifier in ${hl"${whereFound.owner.toString}"}"""
 
       /** Check that any previously found result from an inner context
        *  does properly shadow the new one from an outer context.
@@ -166,9 +170,9 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         else {
           if (!scala2pkg && !previous.isError && !found.isError) {
             error(
-              ex"""reference to $name is ambiguous;
-                  |it is both ${bindingString(newPrec, ctx, "")}
-                  |and ${bindingString(prevPrec, prevCtx, " subsequently")}""",
+              ex"""|reference to `$name` is ambiguous
+                   |it is both ${bindingString(newPrec, ctx, "")}
+                   |and ${bindingString(prevPrec, prevCtx, " subsequently")}""",
               tree.pos)
           }
           previous
@@ -181,7 +185,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         def checkUnambiguous(found: Type) = {
           val other = namedImportRef(site, selectors.tail)
           if (other.exists && found.exists && (found != other))
-            error(em"reference to $name is ambiguous; it is imported twice in ${ctx.tree}",
+            error(em"reference to `$name` is ambiguous; it is imported twice in ${ctx.tree}",
                   tree.pos)
           found
         }
@@ -839,11 +843,11 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
             mapOver(t)
         }
       }
-      override def transform(tree: Tree)(implicit ctx: Context) =
-        super.transform(tree.withType(elimWildcardSym(tree.tpe))) match {
+      override def transform(trt: Tree)(implicit ctx: Context) =
+        super.transform(trt.withType(elimWildcardSym(trt.tpe))) match {
           case b: Bind =>
             if (ctx.scope.lookup(b.name) == NoSymbol) ctx.enter(b.symbol)
-            else ctx.error(em"duplicate pattern variable: ${b.name}", b.pos)
+            else ctx.explainError(DuplicateBind(b, tree), b.pos)
             b.symbol.info = elimWildcardSym(b.symbol.info)
             b
           case t => t

From 1946f94d34a929055c2f0d2dd231c5f5e634c536 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 19:20:11 +0200
Subject: [PATCH 08/53] Change layout of ErrorMessages

---
 .../tools/dotc/parsing/JavaParsers.scala      |   1 +
 .../tools/dotc/parsing/MarkupParsers.scala    |   1 +
 src/dotty/tools/dotc/parsing/Parsers.scala    |   9 +-
 .../tools/dotc/reporting/ErrorMessages.scala  | 117 ++++++++++++++++++
 src/dotty/tools/dotc/reporting/Examples.scala | 106 ----------------
 src/dotty/tools/dotc/reporting/Reporter.scala |  18 +--
 src/dotty/tools/dotc/typer/Typer.scala        |   3 +-
 7 files changed, 135 insertions(+), 120 deletions(-)
 create mode 100644 src/dotty/tools/dotc/reporting/ErrorMessages.scala
 delete mode 100644 src/dotty/tools/dotc/reporting/Examples.scala

diff --git a/src/dotty/tools/dotc/parsing/JavaParsers.scala b/src/dotty/tools/dotc/parsing/JavaParsers.scala
index ed7cf9e3f9cd..90eb908776e7 100644
--- a/src/dotty/tools/dotc/parsing/JavaParsers.scala
+++ b/src/dotty/tools/dotc/parsing/JavaParsers.scala
@@ -30,6 +30,7 @@ import scala.reflect.internal.util.Collections._
 object JavaParsers {
 
   import ast.untpd._
+  import reporting.ErrorMessages.Syntax._
 
   class JavaParser(source: SourceFile)(implicit ctx: Context) extends ParserCommon(source) {
 
diff --git a/src/dotty/tools/dotc/parsing/MarkupParsers.scala b/src/dotty/tools/dotc/parsing/MarkupParsers.scala
index f648b9e2cdeb..ea40eb568433 100644
--- a/src/dotty/tools/dotc/parsing/MarkupParsers.scala
+++ b/src/dotty/tools/dotc/parsing/MarkupParsers.scala
@@ -32,6 +32,7 @@ import Utility._
 object MarkupParsers {
 
   import ast.untpd._
+  import reporting.ErrorMessages.Syntax._
 
   case object MissingEndTagControl extends ControlThrowable {
     override def getMessage = "start tag was here: "
diff --git a/src/dotty/tools/dotc/parsing/Parsers.scala b/src/dotty/tools/dotc/parsing/Parsers.scala
index e4378d82b108..48422650c34c 100644
--- a/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -17,7 +17,7 @@ import ast.Trees._
 import Decorators._
 import StdNames._
 import util.Positions._
-import reporting.ErrorExplanations._
+import reporting.ErrorMessages._
 import Constants._
 import ScriptParsers._
 import Comments._
@@ -28,6 +28,7 @@ import rewrite.Rewrites.patch
 object Parsers {
 
   import ast.untpd._
+  import reporting.ErrorMessages.Syntax._
 
   case class OpInfo(operand: Tree, operator: Name, offset: Offset)
 
@@ -98,7 +99,7 @@ object Parsers {
     /** Issue an error at given offset if beyond last error offset
       *  and update lastErrorOffset.
       */
-    def syntaxError(expl: Explanation, offset: Int = in.offset): Unit =
+    def syntaxError(expl: ErrorMessage, offset: Int = in.offset): Unit =
       if (offset > lastErrorOffset) {
         syntaxError(expl, Position(offset))
         lastErrorOffset = in.offset
@@ -107,7 +108,7 @@ object Parsers {
     /** Unconditionally issue an error at given position, without
       *  updating lastErrorOffset.
       */
-    def syntaxError(expl: Explanation, pos: Position): Unit =
+    def syntaxError(expl: ErrorMessage, pos: Position): Unit =
       ctx.explainError(expl, source atPos pos)
 
   }
@@ -214,7 +215,7 @@ object Parsers {
       }
     }
 
-    def warning(msg: Explanation, offset: Int = in.offset) =
+    def warning(msg: ErrorMessage, offset: Int = in.offset) =
       ctx.explainWarning(msg, source atPos Position(offset))
 
     def deprecationWarning(msg: String, offset: Int = in.offset) =
diff --git a/src/dotty/tools/dotc/reporting/ErrorMessages.scala b/src/dotty/tools/dotc/reporting/ErrorMessages.scala
new file mode 100644
index 000000000000..7186ccbe24de
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/ErrorMessages.scala
@@ -0,0 +1,117 @@
+package dotty.tools
+package dotc
+package reporting
+
+import dotc.core._
+import Contexts.Context, Decorators._, Symbols._
+import dotc.printing.SyntaxHighlighting._
+import util.{SourcePosition, NoSourcePosition}
+
+object ErrorMessages {
+  import dotc.ast.Trees._
+  import dotc.ast.untpd
+
+  implicit class ShouldExplainCtx(val c: Context) extends AnyVal {
+    def shouldExplain(expl: ErrorMessage): Boolean = {
+      implicit val ctx = c
+      expl match {
+        case _: NoExplanation => false
+        case expl if ctx.settings.explainerrors.value => true
+        case _ => false
+      }
+    }
+  }
+
+  trait ErrorMessage {
+    def kind: String
+    def msg: String
+    def explanation: String
+  }
+
+  case class NoExplanation(msg: String)(implicit val kind: String) extends ErrorMessage {
+    val explanation = ""
+  }
+
+  object Syntax {
+    implicit val kind: String = "Syntax"
+    implicit def stringToErrorMessage(s: String): ErrorMessage = NoExplanation(s)
+
+    abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context, val kind: String) extends ErrorMessage {
+      val explanation = {
+        val tryString = tryBody match {
+          case Block(Nil, untpd.EmptyTree) => "{}"
+          case _ => tryBody.show
+        }
+
+        val code1 =
+          s"""|try $tryString catch {
+              |  case t: Throwable => ???
+              |}""".stripMargin
+
+        val code2 =
+          s"""|try $tryString finally {
+              |  // perform your cleanup here!
+              |}""".stripMargin
+
+        hl"""|Explanation:
+             |============
+             |A ${"try"} expression should be followed by some mechanism to handle any exceptions
+             |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
+             |on any expected exceptions. For example:
+             |
+             |$code1
+             |
+             |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
+             |exception propagate - but still allowing for some clean up in ${"finally"}:
+             |
+             |$code2
+             """.stripMargin
+      }
+    }
+
+    case class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context, override val kind: String)
+    extends EmptyCatchOrFinallyBlock(tryBody) {
+      val msg =
+        hl"""The ${"catch"} block does not contain a valid expression, try adding a case like - `${"case e: Exception =>"}` to the block"""
+    }
+
+    case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context, override val kind: String)
+    extends EmptyCatchOrFinallyBlock(tryBody) {
+      val msg =
+        hl"""A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting its body in a block; no exceptions are handled."""
+    }
+  }
+
+  object Type {
+    implicit val kind: String = "Type"
+    implicit def stringToErrorMessage(s: String): ErrorMessage = NoExplanation(s)
+
+    case class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context, val kind: String) extends ErrorMessage {
+      val msg =
+        em"duplicate pattern variable: `${bind.name}`"
+
+      val explanation = {
+        val pat = tree.pat.show
+        val guard = tree.guard match {
+          case untpd.EmptyTree => ""
+          case guard => s"if ${guard.show}"
+        }
+
+        val body = tree.body match {
+          case Block(Nil, untpd.EmptyTree) => ""
+          case body => s" ${body.show}"
+        }
+
+        val caseDef = s"case $pat$guard => $body"
+
+        hl"""|Explanation
+             |===========
+             |For each ${"case"} bound variable names  have to be unique. In:
+             |
+             |$caseDef
+             |
+             |`${bind.name}` is not unique. Rename one of the binds!""".stripMargin
+      }
+    }
+  }
+}
diff --git a/src/dotty/tools/dotc/reporting/Examples.scala b/src/dotty/tools/dotc/reporting/Examples.scala
deleted file mode 100644
index 652620e2991b..000000000000
--- a/src/dotty/tools/dotc/reporting/Examples.scala
+++ /dev/null
@@ -1,106 +0,0 @@
-package dotty.tools
-package dotc
-package reporting
-
-import dotc.core._
-import Contexts.Context, Decorators._, Symbols._
-import dotc.printing.SyntaxHighlighting._
-import util.{SourcePosition, NoSourcePosition}
-
-object ErrorExplanations {
-  import dotc.ast.Trees._
-  import dotc.ast.untpd
-
-  implicit def stringToExplanation(s: String) = NoExplanation(s)
-
-  implicit class ShouldExplainCtx(val c: Context) extends AnyVal {
-    def shouldExplain(expl: Explanation): Boolean = {
-      implicit val ctx = c
-      expl match {
-        case _: NoExplanation => false
-        case expl if ctx.settings.explainerrors.value => true
-        case _ => false
-      }
-    }
-  }
-
-  trait Explanation {
-    def msg: String
-    def explanation: String
-  }
-
-  case class NoExplanation(msg: String) extends Explanation {
-    val explanation = ""
-  }
-
-  abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends Explanation {
-    val explanation = {
-      val tryString = tryBody match {
-        case Block(Nil, untpd.EmptyTree) => "{}"
-        case _ => tryBody.show
-      }
-
-      val code1 =
-        s"""|try $tryString catch {
-            |  case t: Throwable => ???
-            |}""".stripMargin
-
-      val code2 =
-        s"""|try $tryString finally {
-            |  // perform your cleanup here!
-            |}""".stripMargin
-
-      hl"""|Explanation:
-           |============
-           |A ${"try"} expression should be followed by some mechanism to handle any exceptions
-           |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
-           |on any expected exceptions. For example:
-           |
-           |$code1
-           |
-           |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
-           |exception propagate - but still allowing for some clean up in ${"finally"}:
-           |
-           |$code2
-           """.stripMargin
-    }
-  }
-
-  case class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends EmptyCatchOrFinallyBlock(tryBody) {
-    val msg =
-      hl"""The ${"catch"} block does not contain a valid expression, try adding a case like - `${"case e: Exception =>"}` to the block"""
-  }
-
-  case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends EmptyCatchOrFinallyBlock(tryBody) {
-    val msg =
-      hl"""A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting its body in a block; no exceptions are handled."""
-  }
-
-  case class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context) extends Explanation {
-    val msg =
-      em"duplicate pattern variable: `${bind.name}`"
-
-    val explanation = {
-      val pat = tree.pat.show
-      val guard = tree.guard match {
-        case untpd.EmptyTree => ""
-        case guard => s"if ${guard.show}"
-      }
-
-      val body = tree.body match {
-        case Block(Nil, untpd.EmptyTree) => ""
-        case body => s" ${body.show}"
-      }
-
-      val caseDef = s"case $pat$guard => $body"
-
-      hl"""|Explanation
-           |===========
-           |For each ${"case"} bound variable names  have to be unique. In:
-           |
-           |$caseDef
-           |
-           |`${bind.name}` is not unique. Rename one of the binds!""".stripMargin
-    }
-  }
-}
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index eb9a10a59739..401938859c72 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -13,7 +13,7 @@ import java.lang.System.currentTimeMillis
 import core.Mode
 import interfaces.Diagnostic.{ERROR, WARNING, INFO}
 import dotty.tools.dotc.core.Symbols.Symbol
-import ErrorExplanations._
+import ErrorMessages._
 
 object Reporter {
   class Error(msgFn: => String, pos: SourcePosition) extends Diagnostic(msgFn, pos, ERROR)
@@ -96,10 +96,10 @@ trait Reporting { this: Context =>
   def warning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(new Warning(msg, pos))
 
-  def explainWarning(expl: => Explanation, pos: SourcePosition = NoSourcePosition): Unit = {
-    warning(expl.msg, pos)
-    if (this.shouldExplain(expl))
-      reporter.report(new Info(expl.explanation, NoSourcePosition))
+  def explainWarning(err: => ErrorMessage, pos: SourcePosition = NoSourcePosition): Unit = {
+    warning(err.msg, pos)
+    if (this.shouldExplain(err))
+      reporter.report(new Info(err.explanation, NoSourcePosition))
   }
 
   def strictWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
@@ -111,10 +111,10 @@ trait Reporting { this: Context =>
     reporter.report(new Error(msg, pos))
   }
 
-  def explainError(expl: => Explanation, pos: SourcePosition = NoSourcePosition): Unit = {
-    error(expl.msg, pos)
-    if (this.shouldExplain(expl))
-      reporter.report(new Info(expl.explanation, NoSourcePosition))
+  def explainError(err: => ErrorMessage, pos: SourcePosition = NoSourcePosition): Unit = {
+    error(err.msg, pos)
+    if (this.shouldExplain(err))
+      reporter.report(new Info(err.explanation, NoSourcePosition))
   }
 
   def errorOrMigrationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 19297f9ec29c..6fddd928bde9 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -38,7 +38,7 @@ import NavigateAST._
 import transform.SymUtils._
 import language.implicitConversions
 import printing.SyntaxHighlighting._
-import reporting.ErrorExplanations._
+import reporting.ErrorMessages._
 
 object Typer {
 
@@ -66,6 +66,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
   import tpd.{cpy => _, _}
   import untpd.cpy
   import Dynamic.isDynamicMethod
+  import reporting.ErrorMessages.Type._
 
   /** A temporary data item valid for a single typed ident:
    *  The set of all root import symbols that have been

From 11cfc30baf214d5d69d0d5d79b981ad1c131d0e6 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 19:20:31 +0200
Subject: [PATCH 09/53] Add missing star in docstring

---
 src/dotty/tools/dotc/core/TypeOps.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/dotty/tools/dotc/core/TypeOps.scala b/src/dotty/tools/dotc/core/TypeOps.scala
index 5ba9a3351137..bee69ae691fe 100644
--- a/src/dotty/tools/dotc/core/TypeOps.scala
+++ b/src/dotty/tools/dotc/core/TypeOps.scala
@@ -36,7 +36,7 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
    *  Instead we produce an annotated type that marks the prefix as unsafe:
    *
    *     (x: (C @ UnsafeNonvariant)#T)C#T
-
+   *
    *  We also set a global state flag `unsafeNonvariant` to the current run.
    *  When typing a Select node, typer will check that flag, and if it
    *  points to the current run will scan the result type of the select for

From 15db5f6053badd49aae62a699aa59745288c932d Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 19:20:53 +0200
Subject: [PATCH 10/53] Add smart comment formatting in ConsoleReporter

---
 .../dotc/reporting/ConsoleReporter.scala      | 72 +++++++++++++++++--
 1 file changed, 65 insertions(+), 7 deletions(-)

diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index deb772db5719..a681c1552223 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -8,6 +8,7 @@ import core.Contexts._
 import Reporter._
 import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
+import printing.SyntaxHighlighting._
 
 /**
  * This class implements a Reporter that displays messages on a text
@@ -21,6 +22,7 @@ class ConsoleReporter(
   /** maximal number of error messages to be printed */
   protected def ErrorLimit = 100
 
+<<<<<<< HEAD
   def printPos(pos: SourcePosition): Unit =
     if (pos.exists) {
       printMessage(pos.lineContent.stripLineEnd)
@@ -30,26 +32,82 @@ class ConsoleReporter(
         printPos(pos.outer)
       }
     }
+=======
+  def sourceLine(pos: SourcePosition): (String, Int) = {
+    val lineNum = s"${pos.line}:"
+    (lineNum + hl"${pos.lineContent.stripLineEnd}", lineNum.length)
+  }
+
+  def columnMarker(pos: SourcePosition, offset: Int) =
+    if (pos.startLine == pos.endLine) {
+      val whitespace = " " * (pos.column + offset)
+      val carets =
+        AnnotationColor +
+        ("^" * math.max(1, pos.endColumn - pos.startColumn)) +
+        NoColor
+
+      whitespace + carets
+    } else {
+      " " * (pos.column + offset) + AnnotationColor + "^" + NoColor
+    }
+
+  def errorMsg(pos: SourcePosition, msg: String, offset: Int)(implicit ctx: Context) = {
+    var hasLongLines = false
+    val leastWhitespace = msg.lines.foldLeft(Int.MaxValue) { (minPad, line) =>
+      val lineLength =
+        line.replaceAll("\u001B\\[[;\\d]*m", "").length
+      val padding =
+        math.min(math.max(0, ctx.settings.pageWidth.value - offset - lineLength), offset + pos.startColumn)
+
+      if (padding < minPad) padding
+      else minPad
+    }
+
+    msg
+      .lines
+      .map { line => " " * leastWhitespace + line }
+      .mkString(sys.props("line.separator"))
+  }
+
+  def posStr(pos: SourcePosition, kind: String)(implicit ctx: Context) =
+    if (pos.exists) {
+      val file = pos.source.file.toString
+
+      val outer = if (pos.outer.exists) {
+        s"This location is in code that was inlined at ${pos.outer}:\n" +
+        printStr(pos.outer) + "\n" + "-" * ctx.settings.pageWidth.value
+      } else ""
+
+      s"${Console.CYAN}$kind: $file " +
+      "-" * math.max(ctx.settings.pageWidth.value - file.length - kind.length - 1, 0) +
+      "\n" + outer + NoColor
+    }
+    else ""
 
   /** Prints the message. */
   def printMessage(msg: String): Unit = { writer.print(msg + "\n"); writer.flush() }
 
   /** Prints the message with the given position indication. */
-  def printMessageAndPos(msg: String, pos: SourcePosition)(implicit ctx: Context): Unit = {
-    val posStr = if (pos.exists) s"$pos: " else ""
-    printMessage(posStr + msg)
-    printPos(pos)
+  def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
+    printMessage(posStr(pos, kind))
+    if (pos.exists) {
+      val (src, offset) = sourceLine(pos)
+      val marker = columnMarker(pos, offset)
+      val err = errorMsg(pos, msg, offset)
+
+      printMessage(List(src, marker, err).mkString("\n"))
+    } else printMessage(msg)
   }
 
   override def doReport(d: Diagnostic)(implicit ctx: Context): Unit = d match {
     case d: Error =>
-      printMessageAndPos(s"error: ${d.message}", d.pos)
+      printMessageAndPos(d.message, d.pos, "Error in")
       if (ctx.settings.prompt.value) displayPrompt()
     case d: ConditionalWarning if !d.enablingOption.value =>
     case d: MigrationWarning =>
-      printMessageAndPos(s"migration warning: ${d.message}", d.pos)
+      printMessageAndPos(d.message, d.pos, "Migration Warning in")
     case d: Warning =>
-      printMessageAndPos(s"warning: ${d.message}", d.pos)
+      printMessageAndPos(d.message, d.pos, "Warning in")
     case _ =>
       printMessageAndPos(d.message, d.pos)
   }

From f8456fc71e0fba8c92eb2069a7abc872a59c2567 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 15 Sep 2016 22:28:30 +0200
Subject: [PATCH 11/53] Add error kind to diagnostic

---
 .../tools/dotc/interfaces/Diagnostic.java     |  3 ++
 .../dotc/reporting/ConsoleReporter.scala      | 22 ++++----------
 .../tools/dotc/reporting/Diagnostic.scala     |  2 +-
 .../tools/dotc/reporting/ErrorMessages.scala  |  2 +-
 src/dotty/tools/dotc/reporting/Reporter.scala | 30 +++++++++----------
 5 files changed, 26 insertions(+), 33 deletions(-)

diff --git a/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java b/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
index c46360afaa3d..ed1c37b1c2c2 100644
--- a/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
+++ b/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
@@ -14,6 +14,9 @@ public interface Diagnostic {
   public static final int WARNING = 1;
   public static final int INFO = 0;
 
+  /** @return The kind of message being reported */
+  String kind();
+
   /** @return The message to report */
   String message();
 
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index a681c1552223..5db549b7b606 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -22,17 +22,6 @@ class ConsoleReporter(
   /** maximal number of error messages to be printed */
   protected def ErrorLimit = 100
 
-<<<<<<< HEAD
-  def printPos(pos: SourcePosition): Unit =
-    if (pos.exists) {
-      printMessage(pos.lineContent.stripLineEnd)
-      printMessage(" " * pos.column + "^")
-      if (pos.outer.exists) {
-        printMessage(s"\n... this location is in code that was inlined at ${pos.outer}:\n")
-        printPos(pos.outer)
-      }
-    }
-=======
   def sourceLine(pos: SourcePosition): (String, Int) = {
     val lineNum = s"${pos.line}:"
     (lineNum + hl"${pos.lineContent.stripLineEnd}", lineNum.length)
@@ -78,8 +67,9 @@ class ConsoleReporter(
         printStr(pos.outer) + "\n" + "-" * ctx.settings.pageWidth.value
       } else ""
 
-      s"${Console.CYAN}$kind: $file " +
-      "-" * math.max(ctx.settings.pageWidth.value - file.length - kind.length - 1, 0) +
+      val prefix = s"${Console.CYAN}-- $kind: $file "
+      prefix +
+      ("-" * math.max(ctx.settings.pageWidth.value - prefix.replaceAll("\u001B\\[[;\\d]*m", "").length, 0)) +
       "\n" + outer + NoColor
     }
     else ""
@@ -101,13 +91,13 @@ class ConsoleReporter(
 
   override def doReport(d: Diagnostic)(implicit ctx: Context): Unit = d match {
     case d: Error =>
-      printMessageAndPos(d.message, d.pos, "Error in")
+      printMessageAndPos(d.message, d.pos, d.kind)
       if (ctx.settings.prompt.value) displayPrompt()
     case d: ConditionalWarning if !d.enablingOption.value =>
     case d: MigrationWarning =>
-      printMessageAndPos(d.message, d.pos, "Migration Warning in")
+      printMessageAndPos(d.message, d.pos, d.kind)
     case d: Warning =>
-      printMessageAndPos(d.message, d.pos, "Warning in")
+      printMessageAndPos(d.message, d.pos, d.kind)
     case _ =>
       printMessageAndPos(d.message, d.pos)
   }
diff --git a/src/dotty/tools/dotc/reporting/Diagnostic.scala b/src/dotty/tools/dotc/reporting/Diagnostic.scala
index bcf55e993170..d08636802e53 100644
--- a/src/dotty/tools/dotc/reporting/Diagnostic.scala
+++ b/src/dotty/tools/dotc/reporting/Diagnostic.scala
@@ -11,7 +11,7 @@ object Diagnostic {
   val nonSensicalEndTag = "</nonsensical>"
 }
 
-class Diagnostic(msgFn: => String, val pos: SourcePosition, val level: Int)
+class Diagnostic(msgFn: => String, val pos: SourcePosition, val level: Int, val kind: String)
     extends Exception with interfaces.Diagnostic {
   import Diagnostic._
   private var myMsg: String = null
diff --git a/src/dotty/tools/dotc/reporting/ErrorMessages.scala b/src/dotty/tools/dotc/reporting/ErrorMessages.scala
index 7186ccbe24de..2b4c0db7e9b3 100644
--- a/src/dotty/tools/dotc/reporting/ErrorMessages.scala
+++ b/src/dotty/tools/dotc/reporting/ErrorMessages.scala
@@ -110,7 +110,7 @@ object ErrorMessages {
              |
              |$caseDef
              |
-             |`${bind.name}` is not unique. Rename one of the binds!""".stripMargin
+             |`${bind.name}` is not unique. Rename one of the bound variables!""".stripMargin
       }
     }
   }
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index 401938859c72..db0922b2e51e 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -16,23 +16,23 @@ import dotty.tools.dotc.core.Symbols.Symbol
 import ErrorMessages._
 
 object Reporter {
-  class Error(msgFn: => String, pos: SourcePosition) extends Diagnostic(msgFn, pos, ERROR)
-  class Warning(msgFn: => String, pos: SourcePosition) extends Diagnostic(msgFn, pos, WARNING)
-  class Info(msgFn: => String, pos: SourcePosition) extends Diagnostic(msgFn, pos, INFO)
+  class Error(msgFn: => String, pos: SourcePosition, kind: String = "Error") extends Diagnostic(msgFn, pos, ERROR, kind)
+  class Warning(msgFn: => String, pos: SourcePosition, kind: String = "Warning") extends Diagnostic(msgFn, pos, WARNING, kind)
+  class Info(msgFn: => String, pos: SourcePosition, kind: String = "Info") extends Diagnostic(msgFn, pos, INFO, kind)
 
-  abstract class ConditionalWarning(msgFn: => String, pos: SourcePosition) extends Warning(msgFn, pos) {
+  abstract class ConditionalWarning(msgFn: => String, pos: SourcePosition, kind: String) extends Warning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context): Setting[Boolean]
   }
-  class FeatureWarning(msgFn: => String, pos: SourcePosition) extends ConditionalWarning(msgFn, pos) {
+  class FeatureWarning(msgFn: => String, pos: SourcePosition, kind: String = "Feature Warning") extends ConditionalWarning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context) = ctx.settings.feature
   }
-  class UncheckedWarning(msgFn: => String, pos: SourcePosition) extends ConditionalWarning(msgFn, pos) {
+  class UncheckedWarning(msgFn: => String, pos: SourcePosition, kind: String = "Unchecked Warning") extends ConditionalWarning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context) = ctx.settings.unchecked
   }
-  class DeprecationWarning(msgFn: => String, pos: SourcePosition) extends ConditionalWarning(msgFn, pos) {
+  class DeprecationWarning(msgFn: => String, pos: SourcePosition, kind: String = "Deprecation Warning") extends ConditionalWarning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context) = ctx.settings.deprecation
   }
-  class MigrationWarning(msgFn: => String, pos: SourcePosition) extends ConditionalWarning(msgFn, pos) {
+  class MigrationWarning(msgFn: => String, pos: SourcePosition, kind: String = "Migration Warning") extends ConditionalWarning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context) = ctx.settings.migration
   }
 
@@ -56,19 +56,19 @@ trait Reporting { this: Context =>
     if (this.settings.verbose.value) this.echo(msg, pos)
 
   def echo(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new Info(msg, pos))
+    reporter.report(new Info(msg, pos, "Info"))
 
   def deprecationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new DeprecationWarning(msg, pos))
+    reporter.report(new DeprecationWarning(msg, pos, "Deprecation Warning"))
 
   def migrationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new MigrationWarning(msg, pos))
+    reporter.report(new MigrationWarning(msg, pos, "Migration Warning"))
 
   def uncheckedWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new UncheckedWarning(msg, pos))
+    reporter.report(new UncheckedWarning(msg, pos, "Unchecked Warning"))
 
   def featureWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new FeatureWarning(msg, pos))
+    reporter.report(new FeatureWarning(msg, pos, "Feature Warning"))
 
   def featureWarning(feature: String, featureDescription: String, isScala2Feature: Boolean,
       featureUseSite: Symbol, required: Boolean, pos: SourcePosition): Unit = {
@@ -97,7 +97,7 @@ trait Reporting { this: Context =>
     reporter.report(new Warning(msg, pos))
 
   def explainWarning(err: => ErrorMessage, pos: SourcePosition = NoSourcePosition): Unit = {
-    warning(err.msg, pos)
+    reporter.report(new Warning(err.msg, pos, s"${err.kind} warning"))
     if (this.shouldExplain(err))
       reporter.report(new Info(err.explanation, NoSourcePosition))
   }
@@ -112,7 +112,7 @@ trait Reporting { this: Context =>
   }
 
   def explainError(err: => ErrorMessage, pos: SourcePosition = NoSourcePosition): Unit = {
-    error(err.msg, pos)
+    reporter.report(new Error(err.msg, pos, s"${err.kind} error"))
     if (this.shouldExplain(err))
       reporter.report(new Info(err.explanation, NoSourcePosition))
   }

From fb4f8ce66c406bfb6376396ea0521df063b883e9 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 11:06:40 +0200
Subject: [PATCH 12/53] Rename `ConsoleReporter` => `FancyConsoleReporter`

---
 src/dotty/tools/dotc/Compiler.scala                           | 2 +-
 src/dotty/tools/dotc/core/Contexts.scala                      | 2 +-
 src/dotty/tools/dotc/repl/CompilingInterpreter.scala          | 4 ++--
 .../{ConsoleReporter.scala => FancyConsoleReporter.scala}     | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)
 rename src/dotty/tools/dotc/reporting/{ConsoleReporter.scala => FancyConsoleReporter.scala} (99%)

diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index 178cba7c4080..fb9ce83fca8b 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -8,7 +8,7 @@ import Symbols._
 import Types._
 import Scopes._
 import typer.{FrontEnd, Typer, ImportInfo, RefChecks}
-import reporting.{Reporter, ConsoleReporter}
+import reporting.{Reporter, FancyConsoleReporter}
 import Phases.Phase
 import transform._
 import transform.TreeTransforms.{TreeTransform, TreeTransformer}
diff --git a/src/dotty/tools/dotc/core/Contexts.scala b/src/dotty/tools/dotc/core/Contexts.scala
index 5c9fdaf886ee..d1447a98f168 100644
--- a/src/dotty/tools/dotc/core/Contexts.scala
+++ b/src/dotty/tools/dotc/core/Contexts.scala
@@ -501,7 +501,7 @@ object Contexts {
     outer = NoContext
     period = InitialPeriod
     mode = Mode.None
-    typerState = new TyperState(new ConsoleReporter())
+    typerState = new TyperState(new FancyConsoleReporter())
     printerFn = new RefinedPrinter(_)
     owner = NoSymbol
     sstate = settings.defaultState
diff --git a/src/dotty/tools/dotc/repl/CompilingInterpreter.scala b/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
index 163bbea16606..ec2c167ce79d 100644
--- a/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
+++ b/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
@@ -16,7 +16,7 @@ import scala.collection.mutable.{ListBuffer, HashSet, ArrayBuffer}
 //import ast.parser.SyntaxAnalyzer
 import io.{PlainFile, VirtualDirectory}
 import scala.reflect.io.{PlainDirectory, Directory}
-import reporting.{ConsoleReporter, Reporter}
+import reporting.{FancyConsoleReporter, Reporter}
 import core.Flags
 import util.{SourceFile, NameTransformer}
 import io.ClassPath
@@ -117,7 +117,7 @@ class CompilingInterpreter(
     }
   }
 
-  private def newReporter = new ConsoleReporter(Console.in, out) {
+  private def newReporter = new FancyConsoleReporter(Console.in, out) {
     override def printMessage(msg: String) = {
       if (!delayOutput) {
         out.print(/*clean*/(msg) + "\n")
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
similarity index 99%
rename from src/dotty/tools/dotc/reporting/ConsoleReporter.scala
rename to src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
index 5db549b7b606..57f9998a2884 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
@@ -14,7 +14,7 @@ import printing.SyntaxHighlighting._
  * This class implements a Reporter that displays messages on a text
  * console.
  */
-class ConsoleReporter(
+class FancyConsoleReporter(
     reader: BufferedReader = Console.in,
     writer: PrintWriter = new PrintWriter(Console.err, true))
   extends Reporter with UniqueMessagePositions with HideNonSensicalMessages {

From 12ac3054bf4288403babb172c125cdc98cfff012 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 11:49:41 +0200
Subject: [PATCH 13/53] Add ability to choose between fancy and non-fancy
 output

---
 src/dotty/tools/dotc/Compiler.scala           |  6 +-
 .../dotc/printing/SyntaxHighlighting.scala    |  5 +-
 .../dotc/repl/CompilingInterpreter.scala      | 38 ++++++----
 .../dotc/reporting/ConsoleReporter.scala      | 72 +++++++++++++++++++
 .../dotc/reporting/FancyConsoleReporter.scala | 50 ++-----------
 5 files changed, 110 insertions(+), 61 deletions(-)
 create mode 100644 src/dotty/tools/dotc/reporting/ConsoleReporter.scala

diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index fb9ce83fca8b..d6e3cc89b0b5 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -8,7 +8,7 @@ import Symbols._
 import Types._
 import Scopes._
 import typer.{FrontEnd, Typer, ImportInfo, RefChecks}
-import reporting.{Reporter, FancyConsoleReporter}
+import reporting.{Reporter, ConsoleReporter, FancyConsoleReporter}
 import Phases.Phase
 import transform._
 import transform.TreeTransforms.{TreeTransform, TreeTransformer}
@@ -140,6 +140,10 @@ class Compiler {
       .setTyper(new Typer)
       .setMode(Mode.ImplicitsEnabled)
       .setTyperState(new MutableTyperState(ctx.typerState, ctx.typerState.reporter, isCommittable = true))
+      .setReporter(
+        if (ctx.settings.color.value == "never") new ConsoleReporter()
+        else new FancyConsoleReporter()
+      )
     ctx.initialize()(start) // re-initialize the base context with start
     def addImport(ctx: Context, refFn: () => TermRef) =
       ctx.fresh.setImportInfo(ImportInfo.rootImport(refFn)(ctx))
diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 6c7e65a0bfb6..958e71086342 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -11,8 +11,9 @@ import core.Contexts.Context
 object SyntaxHighlighting {
 
   implicit class SyntaxFormatting(val sc: StringContext) extends AnyVal {
-    def hl(args: Any*): String =
-      sc.s(args.map(x => new String(apply(x.toString).toArray)): _*)
+    def hl(args: Any*)(implicit ctx: Context): String =
+      if (ctx.settings.color.value == "never") sc.s(args)
+      else sc.s(args.map(x => new String(apply(x.toString).toArray)): _*)
   }
 
   val NoColor         = Console.RESET
diff --git a/src/dotty/tools/dotc/repl/CompilingInterpreter.scala b/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
index ec2c167ce79d..70b32a16ae33 100644
--- a/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
+++ b/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
@@ -16,7 +16,7 @@ import scala.collection.mutable.{ListBuffer, HashSet, ArrayBuffer}
 //import ast.parser.SyntaxAnalyzer
 import io.{PlainFile, VirtualDirectory}
 import scala.reflect.io.{PlainDirectory, Directory}
-import reporting.{FancyConsoleReporter, Reporter}
+import reporting.{ConsoleReporter, FancyConsoleReporter, Reporter}
 import core.Flags
 import util.{SourceFile, NameTransformer}
 import io.ClassPath
@@ -117,23 +117,31 @@ class CompilingInterpreter(
     }
   }
 
-  private def newReporter = new FancyConsoleReporter(Console.in, out) {
-    override def printMessage(msg: String) = {
-      if (!delayOutput) {
-        out.print(/*clean*/(msg) + "\n")
-          // Suppress clean for now for compiler messages
-          // Otherwise we will completely delete all references to
-          // line$object$ module classes. The previous interpreter did not
-          // have the project because the module class was written without the final `$'
-          // and therefore escaped the purge. We can turn this back on once
-          // we drop the final `$' from module classes.
-        out.flush()
-      } else {
-        previousOutput += (/*clean*/(msg) + "\n")
-      }
+  private def customPrintMessage(msg: String) = {
+    if (!delayOutput) {
+      out.print(/*clean*/(msg) + "\n")
+        // Suppress clean for now for compiler messages
+        // Otherwise we will completely delete all references to
+        // line$object$ module classes. The previous interpreter did not
+        // have the project because the module class was written without the final `$'
+        // and therefore escaped the purge. We can turn this back on once
+        // we drop the final `$' from module classes.
+      out.flush()
+    } else {
+      previousOutput += (/*clean*/(msg) + "\n")
     }
   }
 
+  private def newReporter(implicit ctx: Context) =
+    if (ctx.settings.color.value == "never")
+      new ConsoleReporter(Console.in, out) {
+        override def printMessage(msg: String) = customPrintMessage(msg)
+      }
+    else
+      new FancyConsoleReporter(Console.in, out) {
+        override def printMessage(msg: String) = customPrintMessage(msg)
+      }
+
   /** the previous requests this interpreter has processed */
   private val prevRequests = new ArrayBuffer[Request]()
 
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
new file mode 100644
index 000000000000..1d9423b70f97
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -0,0 +1,72 @@
+package dotty.tools
+package dotc
+package reporting
+
+import scala.collection.mutable
+import util.SourcePosition
+import core.Contexts._
+import Reporter._
+import java.io.{ BufferedReader, IOException, PrintWriter }
+import scala.reflect.internal.util._
+
+/**
+ * This class implements a Reporter that displays messages on a text
+ * console.
+ */
+class ConsoleReporter(
+    reader: BufferedReader = Console.in,
+    writer: PrintWriter = new PrintWriter(Console.err, true))
+  extends Reporter with UniqueMessagePositions with HideNonSensicalMessages {
+
+  /** maximal number of error messages to be printed */
+  protected def ErrorLimit = 100
+
+  def printSourceLine(pos: SourcePosition) =
+    printMessage(pos.lineContent.stripLineEnd)
+
+  def printColumnMarker(pos: SourcePosition) =
+    if (pos.exists) { printMessage(" " * pos.column + "^") }
+
+  /** Prints the message. */
+  def printMessage(msg: String): Unit = { writer.print(msg + "\n"); writer.flush() }
+
+  /** Prints the message with the given position indication. */
+  def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
+    val posStr = if (pos.exists) s"$pos: " else ""
+    printMessage(posStr + kind + msg)
+    if (pos.exists) {
+      printSourceLine(pos)
+      printColumnMarker(pos)
+    }
+  }
+
+  override def doReport(d: Diagnostic)(implicit ctx: Context): Unit = d match {
+    case d: Error =>
+      printMessageAndPos(d.message, d.pos, d.kind)
+      if (ctx.settings.prompt.value) displayPrompt()
+    case d: ConditionalWarning if !d.enablingOption.value =>
+    case d: MigrationWarning =>
+      printMessageAndPos(d.message, d.pos, d.kind)
+    case d: Warning =>
+      printMessageAndPos(d.message, d.pos, d.kind)
+    case _ =>
+      printMessageAndPos(d.message, d.pos, d.kind)
+  }
+
+  def displayPrompt(): Unit = {
+    writer.print("\na)bort, s)tack, r)esume: ")
+    writer.flush()
+    if (reader != null) {
+      val response = reader.read().asInstanceOf[Char].toLower
+      if (response == 'a' || response == 's') {
+        Thread.dumpStack()
+        if (response == 'a')
+          sys.exit(1)
+      }
+      writer.print("\n")
+      writer.flush()
+    }
+  }
+
+  override def flush()(implicit ctx: Context): Unit = { writer.flush() }
+}
diff --git a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
index 57f9998a2884..80f15a4b0c27 100644
--- a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
@@ -11,18 +11,15 @@ import scala.reflect.internal.util._
 import printing.SyntaxHighlighting._
 
 /**
- * This class implements a Reporter that displays messages on a text
- * console.
+ * This class implements a more Fancy version (with colors!) of the regular
+ * `ConsoleReporter`
  */
 class FancyConsoleReporter(
-    reader: BufferedReader = Console.in,
-    writer: PrintWriter = new PrintWriter(Console.err, true))
-  extends Reporter with UniqueMessagePositions with HideNonSensicalMessages {
+  reader: BufferedReader = Console.in,
+  writer: PrintWriter = new PrintWriter(Console.err, true)
+) extends ConsoleReporter(reader, writer) {
 
-  /** maximal number of error messages to be printed */
-  protected def ErrorLimit = 100
-
-  def sourceLine(pos: SourcePosition): (String, Int) = {
+  def sourceLine(pos: SourcePosition)(implicit ctx: Context): (String, Int) = {
     val lineNum = s"${pos.line}:"
     (lineNum + hl"${pos.lineContent.stripLineEnd}", lineNum.length)
   }
@@ -74,11 +71,8 @@ class FancyConsoleReporter(
     }
     else ""
 
-  /** Prints the message. */
-  def printMessage(msg: String): Unit = { writer.print(msg + "\n"); writer.flush() }
-
   /** Prints the message with the given position indication. */
-  def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
+  override def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
     printMessage(posStr(pos, kind))
     if (pos.exists) {
       val (src, offset) = sourceLine(pos)
@@ -88,34 +82,4 @@ class FancyConsoleReporter(
       printMessage(List(src, marker, err).mkString("\n"))
     } else printMessage(msg)
   }
-
-  override def doReport(d: Diagnostic)(implicit ctx: Context): Unit = d match {
-    case d: Error =>
-      printMessageAndPos(d.message, d.pos, d.kind)
-      if (ctx.settings.prompt.value) displayPrompt()
-    case d: ConditionalWarning if !d.enablingOption.value =>
-    case d: MigrationWarning =>
-      printMessageAndPos(d.message, d.pos, d.kind)
-    case d: Warning =>
-      printMessageAndPos(d.message, d.pos, d.kind)
-    case _ =>
-      printMessageAndPos(d.message, d.pos)
-  }
-
-  def displayPrompt(): Unit = {
-    writer.print("\na)bort, s)tack, r)esume: ")
-    writer.flush()
-    if (reader != null) {
-      val response = reader.read().asInstanceOf[Char].toLower
-      if (response == 'a' || response == 's') {
-        Thread.dumpStack()
-        if (response == 'a')
-          sys.exit(1)
-      }
-      writer.print("\n")
-      writer.flush()
-    }
-  }
-
-  override def flush()(implicit ctx: Context): Unit = { writer.flush() }
 }

From 18a69f7bd230bc06696e41be53a6735aa6e94ccc Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 13:34:57 +0200
Subject: [PATCH 14/53] Rename Diagnostic to diagnostic.Message

---
 .../tools/dotc/printing/Formatting.scala      |  5 ++-
 .../dotc/reporting/ConsoleReporter.scala      | 19 ++++----
 .../reporting/HideNonSensicalMessages.scala   |  7 +--
 src/dotty/tools/dotc/reporting/Reporter.scala | 43 ++++++++++++-------
 .../tools/dotc/reporting/StoreReporter.scala  | 13 +++---
 .../dotc/reporting/ThrowingReporter.scala     |  7 +--
 .../reporting/UniqueMessagePositions.scala    | 13 +++---
 .../{ => diagnostic}/Diagnostic.scala         |  9 ++--
 .../tools/dotc/typer/ErrorReporting.scala     |  1 -
 9 files changed, 67 insertions(+), 50 deletions(-)
 rename src/dotty/tools/dotc/reporting/{ => diagnostic}/Diagnostic.scala (87%)

diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index 8921c56a332a..f1bb57bd5279 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -8,7 +8,7 @@ import collection.Map
 import Decorators._
 import scala.annotation.switch
 import scala.util.control.NonFatal
-import reporting.Diagnostic
+import reporting.diagnostic.Message
 
 object Formatting {
 
@@ -75,7 +75,8 @@ object Formatting {
         case _ => true
       }
       val str = super.showArg(arg)
-      if (isSensical(arg)) str else Diagnostic.nonSensicalStartTag + str + Diagnostic.nonSensicalEndTag
+      if (isSensical(arg)) str
+      else Message.nonSensicalStartTag + str + Message.nonSensicalEndTag
     }
   }
 
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 1d9423b70f97..1ed889683e77 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -8,6 +8,7 @@ import core.Contexts._
 import Reporter._
 import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
+import diagnostic.Message
 
 /**
  * This class implements a Reporter that displays messages on a text
@@ -40,17 +41,17 @@ class ConsoleReporter(
     }
   }
 
-  override def doReport(d: Diagnostic)(implicit ctx: Context): Unit = d match {
-    case d: Error =>
-      printMessageAndPos(d.message, d.pos, d.kind)
+  override def doReport(m: Message)(implicit ctx: Context): Unit = m match {
+    case m: Error =>
+      printMessageAndPos(m.message, m.pos, m.kind)
       if (ctx.settings.prompt.value) displayPrompt()
-    case d: ConditionalWarning if !d.enablingOption.value =>
-    case d: MigrationWarning =>
-      printMessageAndPos(d.message, d.pos, d.kind)
-    case d: Warning =>
-      printMessageAndPos(d.message, d.pos, d.kind)
+    case m: ConditionalWarning if !m.enablingOption.value =>
+    case m: MigrationWarning =>
+      printMessageAndPos(m.message, m.pos, m.kind)
+    case m: Warning =>
+      printMessageAndPos(m.message, m.pos, m.kind)
     case _ =>
-      printMessageAndPos(d.message, d.pos, d.kind)
+      printMessageAndPos(m.message, m.pos, m.kind)
   }
 
   def displayPrompt(): Unit = {
diff --git a/src/dotty/tools/dotc/reporting/HideNonSensicalMessages.scala b/src/dotty/tools/dotc/reporting/HideNonSensicalMessages.scala
index a325fe9f707e..140777275f54 100644
--- a/src/dotty/tools/dotc/reporting/HideNonSensicalMessages.scala
+++ b/src/dotty/tools/dotc/reporting/HideNonSensicalMessages.scala
@@ -3,6 +3,7 @@ package dotc
 package reporting
 
 import core.Contexts.Context
+import diagnostic.Message
 
 /**
  * This trait implements `isHidden` so that we avoid reporting non-sensical messages.
@@ -11,9 +12,9 @@ trait HideNonSensicalMessages extends Reporter {
   /** Hides non-sensical messages, unless we haven't reported any error yet or
    *  `-Yshow-suppressed-errors` is set.
    */
-  override def isHidden(d: Diagnostic)(implicit ctx: Context): Boolean =
-    super.isHidden(d) || {
-        d.isNonSensical &&
+  override def isHidden(m: Message)(implicit ctx: Context): Boolean =
+    super.isHidden(m) || {
+        m.isNonSensical &&
         hasErrors && // if there are no errors yet, report even if diagnostic is non-sensical
         !ctx.settings.YshowSuppressedErrors.value
     }
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index db0922b2e51e..8c9308ba5612 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -13,36 +13,47 @@ import java.lang.System.currentTimeMillis
 import core.Mode
 import interfaces.Diagnostic.{ERROR, WARNING, INFO}
 import dotty.tools.dotc.core.Symbols.Symbol
+import diagnostic.Message
 import ErrorMessages._
 
 object Reporter {
-  class Error(msgFn: => String, pos: SourcePosition, kind: String = "Error") extends Diagnostic(msgFn, pos, ERROR, kind)
-  class Warning(msgFn: => String, pos: SourcePosition, kind: String = "Warning") extends Diagnostic(msgFn, pos, WARNING, kind)
-  class Info(msgFn: => String, pos: SourcePosition, kind: String = "Info") extends Diagnostic(msgFn, pos, INFO, kind)
+  class Error(msgFn: => String, pos: SourcePosition, kind: String = "Error")
+  extends Message(msgFn, pos, ERROR, kind)
 
-  abstract class ConditionalWarning(msgFn: => String, pos: SourcePosition, kind: String) extends Warning(msgFn, pos, kind) {
+  class Warning(msgFn: => String, pos: SourcePosition, kind: String = "Warning")
+  extends Message(msgFn, pos, WARNING, kind)
+
+  class Info(msgFn: => String, pos: SourcePosition, kind: String = "Info")
+  extends Message(msgFn, pos, INFO, kind)
+
+  abstract class ConditionalWarning(msgFn: => String, pos: SourcePosition, kind: String)
+  extends Warning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context): Setting[Boolean]
   }
-  class FeatureWarning(msgFn: => String, pos: SourcePosition, kind: String = "Feature Warning") extends ConditionalWarning(msgFn, pos, kind) {
+  class FeatureWarning(msgFn: => String, pos: SourcePosition, kind: String = "Feature Warning")
+  extends ConditionalWarning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context) = ctx.settings.feature
   }
-  class UncheckedWarning(msgFn: => String, pos: SourcePosition, kind: String = "Unchecked Warning") extends ConditionalWarning(msgFn, pos, kind) {
+  class UncheckedWarning(msgFn: => String, pos: SourcePosition, kind: String = "Unchecked Warning")
+  extends ConditionalWarning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context) = ctx.settings.unchecked
   }
-  class DeprecationWarning(msgFn: => String, pos: SourcePosition, kind: String = "Deprecation Warning") extends ConditionalWarning(msgFn, pos, kind) {
+  class DeprecationWarning(msgFn: => String, pos: SourcePosition, kind: String = "Deprecation Warning")
+  extends ConditionalWarning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context) = ctx.settings.deprecation
   }
-  class MigrationWarning(msgFn: => String, pos: SourcePosition, kind: String = "Migration Warning") extends ConditionalWarning(msgFn, pos, kind) {
+  class MigrationWarning(msgFn: => String, pos: SourcePosition, kind: String = "Migration Warning") extends
+  ConditionalWarning(msgFn, pos, kind) {
     def enablingOption(implicit ctx: Context) = ctx.settings.migration
   }
 
   /** Convert a SimpleReporter into a real Reporter */
   def fromSimpleReporter(simple: interfaces.SimpleReporter): Reporter =
     new Reporter with UniqueMessagePositions with HideNonSensicalMessages {
-      override def doReport(d: Diagnostic)(implicit ctx: Context): Unit = d match {
-        case d: ConditionalWarning if !d.enablingOption.value =>
+      override def doReport(m: Message)(implicit ctx: Context): Unit = m match {
+        case m: ConditionalWarning if !m.enablingOption.value =>
         case _ =>
-          simple.report(d)
+          simple.report(m)
       }
     }
 }
@@ -211,7 +222,7 @@ trait Reporting { this: Context =>
 abstract class Reporter extends interfaces.ReporterResult {
 
   /** Report a diagnostic */
-  def doReport(d: Diagnostic)(implicit ctx: Context): Unit
+  def doReport(d: Message)(implicit ctx: Context): Unit
 
   /** Whether very long lines can be truncated.  This exists so important
    *  debugging information (like printing the classpath) is not rendered
@@ -226,7 +237,7 @@ abstract class Reporter extends interfaces.ReporterResult {
     finally _truncationOK = saved
   }
 
-  type ErrorHandler = Diagnostic => Context => Unit
+  type ErrorHandler = Message => Context => Unit
   private var incompleteHandler: ErrorHandler = d => c => report(d)(c)
   def withIncompleteHandler[T](handler: ErrorHandler)(op: => T): T = {
     val saved = incompleteHandler
@@ -255,7 +266,7 @@ abstract class Reporter extends interfaces.ReporterResult {
     override def default(key: String) = 0
   }
 
-  def report(d: Diagnostic)(implicit ctx: Context): Unit =
+  def report(d: Message)(implicit ctx: Context): Unit =
     if (!isHidden(d)) {
       doReport(d)(ctx.addMode(Mode.Printing))
       d match {
@@ -269,7 +280,7 @@ abstract class Reporter extends interfaces.ReporterResult {
       }
     }
 
-  def incomplete(d: Diagnostic)(implicit ctx: Context): Unit =
+  def incomplete(d: Message)(implicit ctx: Context): Unit =
     incompleteHandler(d)(ctx)
 
 
@@ -302,7 +313,7 @@ abstract class Reporter extends interfaces.ReporterResult {
   }
 
   /** Should this diagnostic not be reported at all? */
-  def isHidden(d: Diagnostic)(implicit ctx: Context): Boolean = ctx.mode.is(Mode.Printing)
+  def isHidden(m: Message)(implicit ctx: Context): Boolean = ctx.mode.is(Mode.Printing)
 
   /** Does this reporter contain not yet reported errors or warnings? */
   def hasPending: Boolean = false
diff --git a/src/dotty/tools/dotc/reporting/StoreReporter.scala b/src/dotty/tools/dotc/reporting/StoreReporter.scala
index b7b7c1af0312..dd5935f4c5fe 100644
--- a/src/dotty/tools/dotc/reporting/StoreReporter.scala
+++ b/src/dotty/tools/dotc/reporting/StoreReporter.scala
@@ -6,24 +6,25 @@ import core.Contexts.Context
 import collection.mutable
 import Reporter.{Error, Warning}
 import config.Printers.typr
+import diagnostic.Message
 
 /**
  * This class implements a Reporter that stores all messages
  */
 class StoreReporter(outer: Reporter) extends Reporter {
 
-  private var infos: mutable.ListBuffer[Diagnostic] = null
+  private var infos: mutable.ListBuffer[Message] = null
 
-  def doReport(d: Diagnostic)(implicit ctx: Context): Unit = {
-    typr.println(s">>>> StoredError: ${d.message}") // !!! DEBUG
+  def doReport(m: Message)(implicit ctx: Context): Unit = {
+    typr.println(s">>>> StoredError: ${m.message}") // !!! DEBUG
     if (infos == null) infos = new mutable.ListBuffer
-    infos += d
+    infos += m
   }
 
   override def hasPending: Boolean = infos != null && {
     infos exists {
-      case d: Error => true
-      case d: Warning => true
+      case _: Error => true
+      case _: Warning => true
       case _ => false
     }
   }
diff --git a/src/dotty/tools/dotc/reporting/ThrowingReporter.scala b/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
index 0264530369f5..25adc6a415fc 100644
--- a/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
@@ -4,6 +4,7 @@ package reporting
 
 import core.Contexts.Context
 import collection.mutable
+import diagnostic.Message
 import Reporter._
 
 /**
@@ -11,8 +12,8 @@ import Reporter._
  * info to the underlying reporter.
  */
 class ThrowingReporter(reportInfo: Reporter) extends Reporter {
-  def doReport(d: Diagnostic)(implicit ctx: Context): Unit = d match {
-    case _: Error => throw d
-    case _ => reportInfo.doReport(d)
+  def doReport(m: Message)(implicit ctx: Context): Unit = m match {
+    case _: Error => throw m
+    case _ => reportInfo.doReport(m)
   }
 }
diff --git a/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala b/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
index 32554e6b6b16..1ef8b34474a8 100644
--- a/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
+++ b/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
@@ -5,6 +5,7 @@ package reporting
 import scala.collection.mutable
 import util.{SourcePosition, SourceFile}
 import core.Contexts.Context
+import diagnostic.Message
 
 /**
  * This trait implements `isHidden` so that multiple messages per position
@@ -17,12 +18,12 @@ trait UniqueMessagePositions extends Reporter {
   /** Logs a position and returns true if it was already logged.
    *  @note  Two positions are considered identical for logging if they have the same point.
    */
-  override def isHidden(d: Diagnostic)(implicit ctx: Context): Boolean =
-    super.isHidden(d) || {
-      d.pos.exists && {
-        positions get (ctx.source, d.pos.point) match {
-          case Some(level) if level >= d.level => true
-          case _ => positions((ctx.source, d.pos.point)) = d.level; false
+  override def isHidden(m: Message)(implicit ctx: Context): Boolean =
+    super.isHidden(m) || {
+      m.pos.exists && {
+        positions get (ctx.source, m.pos.point) match {
+          case Some(level) if level >= m.level => true
+          case _ => positions((ctx.source, m.pos.point)) = m.level; false
         }
       }
     }
diff --git a/src/dotty/tools/dotc/reporting/Diagnostic.scala b/src/dotty/tools/dotc/reporting/diagnostic/Diagnostic.scala
similarity index 87%
rename from src/dotty/tools/dotc/reporting/Diagnostic.scala
rename to src/dotty/tools/dotc/reporting/diagnostic/Diagnostic.scala
index d08636802e53..230c1edc0d7f 100644
--- a/src/dotty/tools/dotc/reporting/Diagnostic.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Diagnostic.scala
@@ -1,19 +1,20 @@
 package dotty.tools
 package dotc
 package reporting
+package diagnostic
 
 import util.SourcePosition
 
 import java.util.Optional
 
-object Diagnostic {
+object Message {
   val nonSensicalStartTag = "<nonsensical>"
   val nonSensicalEndTag = "</nonsensical>"
 }
 
-class Diagnostic(msgFn: => String, val pos: SourcePosition, val level: Int, val kind: String)
-    extends Exception with interfaces.Diagnostic {
-  import Diagnostic._
+class Message(msgFn: => String, val pos: SourcePosition, val level: Int, val kind: String)
+extends Exception with interfaces.Diagnostic {
+  import Message._
   private var myMsg: String = null
   private var myIsNonSensical: Boolean = false
 
diff --git a/src/dotty/tools/dotc/typer/ErrorReporting.scala b/src/dotty/tools/dotc/typer/ErrorReporting.scala
index ad84ff583dd2..c8e76aa97b58 100644
--- a/src/dotty/tools/dotc/typer/ErrorReporting.scala
+++ b/src/dotty/tools/dotc/typer/ErrorReporting.scala
@@ -8,7 +8,6 @@ import Trees._
 import Types._, ProtoTypes._, Contexts._, Decorators._, Denotations._, Symbols._
 import Applications._, Implicits._, Flags._
 import util.Positions._
-import reporting.Diagnostic
 import printing.{Showable, RefinedPrinter}
 import scala.collection.mutable
 import java.util.regex.Matcher.quoteReplacement

From 2b2cfe71aacb50e91d6956f0d4ee7d555537698a Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 13:56:59 +0200
Subject: [PATCH 15/53] Refactor common error messages to `diagnostic.basic`

---
 .../tools/dotc/interfaces/Diagnostic.java     |  3 +
 .../dotc/printing/SyntaxHighlighting.scala    |  2 +-
 .../dotc/reporting/ConsoleReporter.scala      |  1 +
 src/dotty/tools/dotc/reporting/Reporter.scala | 34 +-------
 .../tools/dotc/reporting/StoreReporter.scala  |  1 +
 .../dotc/reporting/ThrowingReporter.scala     |  1 +
 .../{Diagnostic.scala => Message.scala}       | 35 +++++---
 .../dotc/reporting/diagnostic/basic.scala     | 80 +++++++++++++++++++
 .../dotc/reporting/diagnostic/parser.scala    |  8 ++
 9 files changed, 121 insertions(+), 44 deletions(-)
 rename src/dotty/tools/dotc/reporting/diagnostic/{Diagnostic.scala => Message.scala} (57%)
 create mode 100644 src/dotty/tools/dotc/reporting/diagnostic/basic.scala
 create mode 100644 src/dotty/tools/dotc/reporting/diagnostic/parser.scala

diff --git a/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java b/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
index ed1c37b1c2c2..e62c1193e921 100644
--- a/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
+++ b/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
@@ -20,6 +20,9 @@ public interface Diagnostic {
   /** @return The message to report */
   String message();
 
+  /** @return The explanation behind the message */
+  String explanation();
+
   /** @return Level of the diagnostic, can be either ERROR, WARNING or INFO */
   int level();
 
diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 958e71086342..d94f6796d8d7 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -12,7 +12,7 @@ object SyntaxHighlighting {
 
   implicit class SyntaxFormatting(val sc: StringContext) extends AnyVal {
     def hl(args: Any*)(implicit ctx: Context): String =
-      if (ctx.settings.color.value == "never") sc.s(args)
+      if (ctx.settings.color.value == "never") sc.s(args: _*)
       else sc.s(args.map(x => new String(apply(x.toString).toArray)): _*)
   }
 
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 1ed889683e77..4d8897820d07 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -9,6 +9,7 @@ import Reporter._
 import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
 import diagnostic.Message
+import diagnostic.basic._
 
 /**
  * This class implements a Reporter that displays messages on a text
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index 8c9308ba5612..ccbae94bfcb8 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -4,49 +4,17 @@ package reporting
 
 import core.Contexts._
 import util.{SourcePosition, NoSourcePosition}
-import util.{SourceFile, NoSource}
 import core.Decorators.PhaseListDecorator
 import collection.mutable
-import config.Settings.Setting
 import config.Printers
 import java.lang.System.currentTimeMillis
 import core.Mode
-import interfaces.Diagnostic.{ERROR, WARNING, INFO}
 import dotty.tools.dotc.core.Symbols.Symbol
 import diagnostic.Message
 import ErrorMessages._
+import diagnostic.basic._
 
 object Reporter {
-  class Error(msgFn: => String, pos: SourcePosition, kind: String = "Error")
-  extends Message(msgFn, pos, ERROR, kind)
-
-  class Warning(msgFn: => String, pos: SourcePosition, kind: String = "Warning")
-  extends Message(msgFn, pos, WARNING, kind)
-
-  class Info(msgFn: => String, pos: SourcePosition, kind: String = "Info")
-  extends Message(msgFn, pos, INFO, kind)
-
-  abstract class ConditionalWarning(msgFn: => String, pos: SourcePosition, kind: String)
-  extends Warning(msgFn, pos, kind) {
-    def enablingOption(implicit ctx: Context): Setting[Boolean]
-  }
-  class FeatureWarning(msgFn: => String, pos: SourcePosition, kind: String = "Feature Warning")
-  extends ConditionalWarning(msgFn, pos, kind) {
-    def enablingOption(implicit ctx: Context) = ctx.settings.feature
-  }
-  class UncheckedWarning(msgFn: => String, pos: SourcePosition, kind: String = "Unchecked Warning")
-  extends ConditionalWarning(msgFn, pos, kind) {
-    def enablingOption(implicit ctx: Context) = ctx.settings.unchecked
-  }
-  class DeprecationWarning(msgFn: => String, pos: SourcePosition, kind: String = "Deprecation Warning")
-  extends ConditionalWarning(msgFn, pos, kind) {
-    def enablingOption(implicit ctx: Context) = ctx.settings.deprecation
-  }
-  class MigrationWarning(msgFn: => String, pos: SourcePosition, kind: String = "Migration Warning") extends
-  ConditionalWarning(msgFn, pos, kind) {
-    def enablingOption(implicit ctx: Context) = ctx.settings.migration
-  }
-
   /** Convert a SimpleReporter into a real Reporter */
   def fromSimpleReporter(simple: interfaces.SimpleReporter): Reporter =
     new Reporter with UniqueMessagePositions with HideNonSensicalMessages {
diff --git a/src/dotty/tools/dotc/reporting/StoreReporter.scala b/src/dotty/tools/dotc/reporting/StoreReporter.scala
index dd5935f4c5fe..2aa2253a077b 100644
--- a/src/dotty/tools/dotc/reporting/StoreReporter.scala
+++ b/src/dotty/tools/dotc/reporting/StoreReporter.scala
@@ -7,6 +7,7 @@ import collection.mutable
 import Reporter.{Error, Warning}
 import config.Printers.typr
 import diagnostic.Message
+import diagnostic.basic._
 
 /**
  * This class implements a Reporter that stores all messages
diff --git a/src/dotty/tools/dotc/reporting/ThrowingReporter.scala b/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
index 25adc6a415fc..b08145654312 100644
--- a/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
@@ -5,6 +5,7 @@ package reporting
 import core.Contexts.Context
 import collection.mutable
 import diagnostic.Message
+import diagnostic.basic.Error
 import Reporter._
 
 /**
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Diagnostic.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
similarity index 57%
rename from src/dotty/tools/dotc/reporting/diagnostic/Diagnostic.scala
rename to src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index 230c1edc0d7f..90ebf11a20f1 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Diagnostic.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -12,8 +12,13 @@ object Message {
   val nonSensicalEndTag = "</nonsensical>"
 }
 
-class Message(msgFn: => String, val pos: SourcePosition, val level: Int, val kind: String)
-extends Exception with interfaces.Diagnostic {
+class Message(
+  msgFn: => String,
+  val pos: SourcePosition,
+  val level: Int,
+  val kind: String,
+  val explanation: String
+) extends Exception with interfaces.Diagnostic {
   import Message._
   private var myMsg: String = null
   private var myIsNonSensical: Boolean = false
@@ -27,22 +32,32 @@ extends Exception with interfaces.Diagnostic {
       myMsg = msgFn
       if (myMsg.contains(nonSensicalStartTag)) {
         myIsNonSensical = true
-        // myMsg might be composed of several d"..." invocations -> nested nonsensical tags possible
-        myMsg = myMsg.replaceAllLiterally(nonSensicalStartTag, "").replaceAllLiterally(nonSensicalEndTag, "")
+        // myMsg might be composed of several d"..." invocations -> nested
+        // nonsensical tags possible
+        myMsg =
+          myMsg
+          .replaceAllLiterally(nonSensicalStartTag, "")
+          .replaceAllLiterally(nonSensicalEndTag, "")
       }
     }
     myMsg
   }
 
-  /** A message is non-sensical if it contains references to <nonsensical> tags.
-   *  Such tags are inserted by the error diagnostic framework if a message
-   *  contains references to internally generated error types. Normally we
-   *  want to suppress error messages referring to types like this because
-   *  they look weird and are normally follow-up errors to something that
-   *  was diagnosed before.
+  /** A message is non-sensical if it contains references to <nonsensical>
+   *  tags.  Such tags are inserted by the error diagnostic framework if a
+   *  message contains references to internally generated error types. Normally
+   *  we want to suppress error messages referring to types like this because
+   *  they look weird and are normally follow-up errors to something that was
+   *  diagnosed before.
    */
   def isNonSensical = { message; myIsNonSensical }
 
   override def toString = s"$getClass at $pos: $message"
   override def getMessage() = message
 }
+
+object NoExplanation {
+  def unapply(m: Message): Option[Message] =
+    if (m.explanation == "") Some(m)
+    else None
+}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/basic.scala b/src/dotty/tools/dotc/reporting/diagnostic/basic.scala
new file mode 100644
index 000000000000..2da986d89c22
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/diagnostic/basic.scala
@@ -0,0 +1,80 @@
+package dotty.tools
+package dotc
+package reporting
+package diagnostic
+
+import dotc.core.Contexts.Context
+import util.{SourceFile, NoSource}
+import util.{SourcePosition, NoSourcePosition}
+import config.Settings.Setting
+import interfaces.Diagnostic.{ERROR, WARNING, INFO}
+
+object basic {
+
+  class Error(
+    msgFn: => String,
+    pos: SourcePosition,
+    kind: String = "Error",
+    explanation: String = ""
+  ) extends Message(msgFn, pos, ERROR, kind, explanation)
+
+  class Warning(
+    msgFn: => String,
+    pos: SourcePosition,
+    kind: String = "Warning",
+    explanation: String = ""
+  ) extends Message(msgFn, pos, WARNING, kind, explanation)
+
+  class Info(
+    msgFn: => String,
+    pos: SourcePosition,
+    kind: String = "Info",
+    explanation: String = ""
+  ) extends Message(msgFn, pos, INFO, kind, explanation)
+
+  abstract class ConditionalWarning(
+    msgFn: => String,
+    pos: SourcePosition,
+    kind: String,
+    explanation: String = ""
+  ) extends Warning(msgFn, pos, kind, explanation) {
+    def enablingOption(implicit ctx: Context): Setting[Boolean]
+  }
+
+  class FeatureWarning(
+    msgFn: => String,
+    pos: SourcePosition,
+    kind: String = "Feature Warning",
+    explanation: String = ""
+  ) extends ConditionalWarning(msgFn, pos, kind, explanation) {
+    def enablingOption(implicit ctx: Context) = ctx.settings.feature
+  }
+
+  class UncheckedWarning(
+    msgFn: => String,
+    pos: SourcePosition,
+    kind: String = "Unchecked Warning",
+    explanation: String = ""
+  ) extends ConditionalWarning(msgFn, pos, kind, explanation) {
+    def enablingOption(implicit ctx: Context) = ctx.settings.unchecked
+  }
+
+  class DeprecationWarning(
+    msgFn: => String,
+    pos: SourcePosition,
+    kind: String = "Deprecation Warning",
+    explanation: String = ""
+  ) extends ConditionalWarning(msgFn, pos, kind, explanation) {
+    def enablingOption(implicit ctx: Context) = ctx.settings.deprecation
+  }
+
+  class MigrationWarning(
+    msgFn: => String,
+    pos: SourcePosition,
+    kind: String = "Migration Warning",
+    explanation: String = ""
+  ) extends ConditionalWarning(msgFn, pos, kind, explanation) {
+    def enablingOption(implicit ctx: Context) = ctx.settings.migration
+  }
+
+}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/parser.scala b/src/dotty/tools/dotc/reporting/diagnostic/parser.scala
new file mode 100644
index 000000000000..b73e353eba79
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/diagnostic/parser.scala
@@ -0,0 +1,8 @@
+package dotty.tools
+package dotc
+package reporting
+package diagnostic
+
+object parser {
+
+}

From 2764609bb17dfc8691d33fcc1c70a9891af59e70 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 18:23:11 +0200
Subject: [PATCH 16/53] Complete better structure to diagnostic messages

---
 .../tools/dotc/config/ScalaSettings.scala     |   2 +-
 .../tools/dotc/parsing/JavaParsers.scala      |   1 -
 .../tools/dotc/parsing/MarkupParsers.scala    |   1 -
 src/dotty/tools/dotc/parsing/Parsers.scala    |  13 +-
 .../dotc/reporting/ConsoleReporter.scala      |   2 +-
 .../tools/dotc/reporting/ErrorMessages.scala  | 117 ------------------
 src/dotty/tools/dotc/reporting/Reporter.scala |  22 ++--
 .../tools/dotc/reporting/StoreReporter.scala  |   2 +-
 .../dotc/reporting/ThrowingReporter.scala     |   2 +-
 .../dotc/reporting/diagnostic/Message.scala   |   7 +-
 .../reporting/diagnostic/MessageCreator.scala |  62 ++++++++++
 .../{basic.scala => messages.scala}           |   2 +-
 .../dotc/reporting/diagnostic/syntax.scala    |  63 ++++++++++
 .../tools/dotc/reporting/diagnostic/tpe.scala |  47 +++++++
 src/dotty/tools/dotc/typer/Typer.scala        |   5 +-
 15 files changed, 198 insertions(+), 150 deletions(-)
 delete mode 100644 src/dotty/tools/dotc/reporting/ErrorMessages.scala
 create mode 100644 src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
 rename src/dotty/tools/dotc/reporting/diagnostic/{basic.scala => messages.scala} (99%)
 create mode 100644 src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
 create mode 100644 src/dotty/tools/dotc/reporting/diagnostic/tpe.scala

diff --git a/src/dotty/tools/dotc/config/ScalaSettings.scala b/src/dotty/tools/dotc/config/ScalaSettings.scala
index a4daefcba200..872cb0667af0 100644
--- a/src/dotty/tools/dotc/config/ScalaSettings.scala
+++ b/src/dotty/tools/dotc/config/ScalaSettings.scala
@@ -23,7 +23,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val migration = BooleanSetting("-migration", "Emit warning and location for migration issues from Scala 2.")
   val encoding = StringSetting("-encoding", "encoding", "Specify character encoding used by source files.", Properties.sourceEncoding)
   val explaintypes = BooleanSetting("-explaintypes", "Explain type errors in more detail.")
-  val explainerrors = BooleanSetting("-explain", "Explain errors in more detail.")
+  val explain = BooleanSetting("-explain", "Explain errors in more detail.")
   val feature = BooleanSetting("-feature", "Emit warning and location for usages of features that should be imported explicitly.")
   val g = ChoiceSetting("-g", "level", "Set level of generated debugging info.", List("none", "source", "line", "vars", "notailcalls"), "vars")
   val help = BooleanSetting("-help", "Print a synopsis of standard options")
diff --git a/src/dotty/tools/dotc/parsing/JavaParsers.scala b/src/dotty/tools/dotc/parsing/JavaParsers.scala
index 90eb908776e7..ed7cf9e3f9cd 100644
--- a/src/dotty/tools/dotc/parsing/JavaParsers.scala
+++ b/src/dotty/tools/dotc/parsing/JavaParsers.scala
@@ -30,7 +30,6 @@ import scala.reflect.internal.util.Collections._
 object JavaParsers {
 
   import ast.untpd._
-  import reporting.ErrorMessages.Syntax._
 
   class JavaParser(source: SourceFile)(implicit ctx: Context) extends ParserCommon(source) {
 
diff --git a/src/dotty/tools/dotc/parsing/MarkupParsers.scala b/src/dotty/tools/dotc/parsing/MarkupParsers.scala
index ea40eb568433..f648b9e2cdeb 100644
--- a/src/dotty/tools/dotc/parsing/MarkupParsers.scala
+++ b/src/dotty/tools/dotc/parsing/MarkupParsers.scala
@@ -32,7 +32,6 @@ import Utility._
 object MarkupParsers {
 
   import ast.untpd._
-  import reporting.ErrorMessages.Syntax._
 
   case object MissingEndTagControl extends ControlThrowable {
     override def getMessage = "start tag was here: "
diff --git a/src/dotty/tools/dotc/parsing/Parsers.scala b/src/dotty/tools/dotc/parsing/Parsers.scala
index 48422650c34c..1b451ced7b6f 100644
--- a/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -17,7 +17,6 @@ import ast.Trees._
 import Decorators._
 import StdNames._
 import util.Positions._
-import reporting.ErrorMessages._
 import Constants._
 import ScriptParsers._
 import Comments._
@@ -28,7 +27,9 @@ import rewrite.Rewrites.patch
 object Parsers {
 
   import ast.untpd._
-  import reporting.ErrorMessages.Syntax._
+  import reporting.diagnostic.MessageCreator
+  import MessageCreator._
+  import reporting.diagnostic.syntax._
 
   case class OpInfo(operand: Tree, operator: Name, offset: Offset)
 
@@ -99,7 +100,7 @@ object Parsers {
     /** Issue an error at given offset if beyond last error offset
       *  and update lastErrorOffset.
       */
-    def syntaxError(expl: ErrorMessage, offset: Int = in.offset): Unit =
+    def syntaxError(expl: MessageCreator, offset: Int = in.offset): Unit =
       if (offset > lastErrorOffset) {
         syntaxError(expl, Position(offset))
         lastErrorOffset = in.offset
@@ -108,7 +109,7 @@ object Parsers {
     /** Unconditionally issue an error at given position, without
       *  updating lastErrorOffset.
       */
-    def syntaxError(expl: ErrorMessage, pos: Position): Unit =
+    def syntaxError(expl: MessageCreator, pos: Position): Unit =
       ctx.explainError(expl, source atPos pos)
 
   }
@@ -215,7 +216,7 @@ object Parsers {
       }
     }
 
-    def warning(msg: ErrorMessage, offset: Int = in.offset) =
+    def warning(msg: MessageCreator, offset: Int = in.offset) =
       ctx.explainWarning(msg, source atPos Position(offset))
 
     def deprecationWarning(msg: String, offset: Int = in.offset) =
@@ -1016,7 +1017,7 @@ object Parsers {
 
           handler match {
             case Block(Nil, EmptyTree) =>
-              syntaxError(EmptyCatchBlock(body), handler.pos)
+              syntaxError(new EmptyCatchBlock(body), handler.pos)
             case _ =>
           }
 
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 4d8897820d07..3a4f60aebbde 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -9,7 +9,7 @@ import Reporter._
 import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
 import diagnostic.Message
-import diagnostic.basic._
+import diagnostic.messages._
 
 /**
  * This class implements a Reporter that displays messages on a text
diff --git a/src/dotty/tools/dotc/reporting/ErrorMessages.scala b/src/dotty/tools/dotc/reporting/ErrorMessages.scala
deleted file mode 100644
index 2b4c0db7e9b3..000000000000
--- a/src/dotty/tools/dotc/reporting/ErrorMessages.scala
+++ /dev/null
@@ -1,117 +0,0 @@
-package dotty.tools
-package dotc
-package reporting
-
-import dotc.core._
-import Contexts.Context, Decorators._, Symbols._
-import dotc.printing.SyntaxHighlighting._
-import util.{SourcePosition, NoSourcePosition}
-
-object ErrorMessages {
-  import dotc.ast.Trees._
-  import dotc.ast.untpd
-
-  implicit class ShouldExplainCtx(val c: Context) extends AnyVal {
-    def shouldExplain(expl: ErrorMessage): Boolean = {
-      implicit val ctx = c
-      expl match {
-        case _: NoExplanation => false
-        case expl if ctx.settings.explainerrors.value => true
-        case _ => false
-      }
-    }
-  }
-
-  trait ErrorMessage {
-    def kind: String
-    def msg: String
-    def explanation: String
-  }
-
-  case class NoExplanation(msg: String)(implicit val kind: String) extends ErrorMessage {
-    val explanation = ""
-  }
-
-  object Syntax {
-    implicit val kind: String = "Syntax"
-    implicit def stringToErrorMessage(s: String): ErrorMessage = NoExplanation(s)
-
-    abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context, val kind: String) extends ErrorMessage {
-      val explanation = {
-        val tryString = tryBody match {
-          case Block(Nil, untpd.EmptyTree) => "{}"
-          case _ => tryBody.show
-        }
-
-        val code1 =
-          s"""|try $tryString catch {
-              |  case t: Throwable => ???
-              |}""".stripMargin
-
-        val code2 =
-          s"""|try $tryString finally {
-              |  // perform your cleanup here!
-              |}""".stripMargin
-
-        hl"""|Explanation:
-             |============
-             |A ${"try"} expression should be followed by some mechanism to handle any exceptions
-             |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
-             |on any expected exceptions. For example:
-             |
-             |$code1
-             |
-             |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
-             |exception propagate - but still allowing for some clean up in ${"finally"}:
-             |
-             |$code2
-             """.stripMargin
-      }
-    }
-
-    case class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context, override val kind: String)
-    extends EmptyCatchOrFinallyBlock(tryBody) {
-      val msg =
-        hl"""The ${"catch"} block does not contain a valid expression, try adding a case like - `${"case e: Exception =>"}` to the block"""
-    }
-
-    case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context, override val kind: String)
-    extends EmptyCatchOrFinallyBlock(tryBody) {
-      val msg =
-        hl"""A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting its body in a block; no exceptions are handled."""
-    }
-  }
-
-  object Type {
-    implicit val kind: String = "Type"
-    implicit def stringToErrorMessage(s: String): ErrorMessage = NoExplanation(s)
-
-    case class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context, val kind: String) extends ErrorMessage {
-      val msg =
-        em"duplicate pattern variable: `${bind.name}`"
-
-      val explanation = {
-        val pat = tree.pat.show
-        val guard = tree.guard match {
-          case untpd.EmptyTree => ""
-          case guard => s"if ${guard.show}"
-        }
-
-        val body = tree.body match {
-          case Block(Nil, untpd.EmptyTree) => ""
-          case body => s" ${body.show}"
-        }
-
-        val caseDef = s"case $pat$guard => $body"
-
-        hl"""|Explanation
-             |===========
-             |For each ${"case"} bound variable names  have to be unique. In:
-             |
-             |$caseDef
-             |
-             |`${bind.name}` is not unique. Rename one of the bound variables!""".stripMargin
-      }
-    }
-  }
-}
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index ccbae94bfcb8..5c3dcccb7bf1 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -10,9 +10,9 @@ import config.Printers
 import java.lang.System.currentTimeMillis
 import core.Mode
 import dotty.tools.dotc.core.Symbols.Symbol
-import diagnostic.Message
-import ErrorMessages._
-import diagnostic.basic._
+import diagnostic.messages._
+import diagnostic._
+import MessageCreator._
 
 object Reporter {
   /** Convert a SimpleReporter into a real Reporter */
@@ -75,10 +75,10 @@ trait Reporting { this: Context =>
   def warning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(new Warning(msg, pos))
 
-  def explainWarning(err: => ErrorMessage, pos: SourcePosition = NoSourcePosition): Unit = {
-    reporter.report(new Warning(err.msg, pos, s"${err.kind} warning"))
-    if (this.shouldExplain(err))
-      reporter.report(new Info(err.explanation, NoSourcePosition))
+  def explainWarning(msg: => MessageCreator, pos: SourcePosition = NoSourcePosition): Unit = {
+    reporter.report(msg.warning(pos))
+    if (this.shouldExplain(msg))
+      reporter.report(new Info(msg.explanation, NoSourcePosition))
   }
 
   def strictWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
@@ -90,10 +90,10 @@ trait Reporting { this: Context =>
     reporter.report(new Error(msg, pos))
   }
 
-  def explainError(err: => ErrorMessage, pos: SourcePosition = NoSourcePosition): Unit = {
-    reporter.report(new Error(err.msg, pos, s"${err.kind} error"))
-    if (this.shouldExplain(err))
-      reporter.report(new Info(err.explanation, NoSourcePosition))
+  def explainError(msg: => MessageCreator, pos: SourcePosition = NoSourcePosition): Unit = {
+    reporter.report(msg.error(pos))
+    if (this.shouldExplain(msg))
+      reporter.report(new Info(msg.explanation, NoSourcePosition))
   }
 
   def errorOrMigrationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
diff --git a/src/dotty/tools/dotc/reporting/StoreReporter.scala b/src/dotty/tools/dotc/reporting/StoreReporter.scala
index 2aa2253a077b..fa4fd991fdf9 100644
--- a/src/dotty/tools/dotc/reporting/StoreReporter.scala
+++ b/src/dotty/tools/dotc/reporting/StoreReporter.scala
@@ -7,7 +7,7 @@ import collection.mutable
 import Reporter.{Error, Warning}
 import config.Printers.typr
 import diagnostic.Message
-import diagnostic.basic._
+import diagnostic.messages._
 
 /**
  * This class implements a Reporter that stores all messages
diff --git a/src/dotty/tools/dotc/reporting/ThrowingReporter.scala b/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
index b08145654312..f4e3b472d83b 100644
--- a/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
@@ -5,7 +5,7 @@ package reporting
 import core.Contexts.Context
 import collection.mutable
 import diagnostic.Message
-import diagnostic.basic.Error
+import diagnostic.messages.Error
 import Reporter._
 
 /**
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index 90ebf11a20f1..d7cfa2e2b3e4 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -4,6 +4,7 @@ package reporting
 package diagnostic
 
 import util.SourcePosition
+import core.Contexts.Context
 
 import java.util.Optional
 
@@ -55,9 +56,3 @@ class Message(
   override def toString = s"$getClass at $pos: $message"
   override def getMessage() = message
 }
-
-object NoExplanation {
-  def unapply(m: Message): Option[Message] =
-    if (m.explanation == "") Some(m)
-    else None
-}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
new file mode 100644
index 000000000000..d74099f4f92e
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
@@ -0,0 +1,62 @@
+package dotty.tools
+package dotc
+package reporting
+package diagnostic
+
+import util.{SourcePosition, NoSourcePosition}
+import core.Contexts.Context
+
+object MessageCreator {
+  implicit class DiagnosticContext(val c: Context) extends AnyVal {
+    def shouldExplain(msg: MessageCreator): Boolean = {
+      implicit val ctx: Context = c
+      msg match {
+        case NoExplanation(_) => false
+        case _ => ctx.settings.explain.value
+      }
+    }
+  }
+
+  implicit def toNoExplanation(str: String) =
+    new NoExplanation(str)
+}
+
+trait MessageCreator {
+  import messages._
+
+  def msg: String
+  def kind: String
+  def explanation: String
+
+  def error(pos: SourcePosition) =
+    new Error(msg, pos, kind, explanation)
+
+  def warning(pos: SourcePosition) =
+    new Warning(msg, pos, kind, explanation)
+
+  def info(pos: SourcePosition) =
+    new Info(msg, pos, kind, explanation)
+
+  def featureWarnign(pos: SourcePosition) =
+    new FeatureWarning(msg, pos, kind, explanation)
+
+  def uncheckedWarning(pos: SourcePosition) =
+    new UncheckedWarning(msg, pos, kind, explanation)
+
+  def deprecationWarning(pos: SourcePosition) =
+    new DeprecationWarning(msg, pos, kind, explanation)
+
+  def migrationWarning(pos: SourcePosition) =
+    new MigrationWarning(msg, pos, kind, explanation)
+}
+
+class NoExplanation(val msg: String) extends MessageCreator {
+  val explanation = ""
+  val kind = ""
+}
+
+object NoExplanation {
+  def unapply(m: MessageCreator): Option[MessageCreator] =
+    if (m.explanation == "") Some(m)
+    else None
+}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/basic.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
similarity index 99%
rename from src/dotty/tools/dotc/reporting/diagnostic/basic.scala
rename to src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 2da986d89c22..382e9a29502c 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/basic.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -9,7 +9,7 @@ import util.{SourcePosition, NoSourcePosition}
 import config.Settings.Setting
 import interfaces.Diagnostic.{ERROR, WARNING, INFO}
 
-object basic {
+object messages {
 
   class Error(
     msgFn: => String,
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala b/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
new file mode 100644
index 000000000000..675cacbedaf4
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
@@ -0,0 +1,63 @@
+package dotty.tools
+package dotc
+package reporting
+package diagnostic
+
+import dotc.core._
+import Contexts.Context, Decorators._, Symbols._
+import dotc.printing.SyntaxHighlighting._
+import util.{SourcePosition, NoSourcePosition}
+
+object syntax {
+  import dotc.ast.Trees._
+  import dotc.ast.untpd
+
+  abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends MessageCreator {
+    val explanation = {
+      val tryString = tryBody match {
+        case Block(Nil, untpd.EmptyTree) => "{}"
+        case _ => tryBody.show
+      }
+
+      val code1 =
+        s"""|try $tryString catch {
+            |  case t: Throwable => ???
+            |}""".stripMargin
+
+      val code2 =
+        s"""|try $tryString finally {
+            |  // perform your cleanup here!
+            |}""".stripMargin
+
+      hl"""|Explanation:
+           |============
+           |A ${"try"} expression should be followed by some mechanism to handle any exceptions
+           |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
+           |on any expected exceptions. For example:
+           |
+           |$code1
+           |
+           |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
+           |exception propagate - but still allowing for some clean up in ${"finally"}:
+           |
+           |$code2
+           """.stripMargin
+    }
+  }
+
+  class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
+  extends EmptyCatchOrFinallyBlock(tryBody) {
+    val kind = "Syntax"
+    val msg =
+      hl"""|The ${"catch"} block does not contain a valid expression, try
+           |adding a case like - `${"case e: Exception =>"}` to the block""".stripMargin
+  }
+
+  case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context)
+  extends EmptyCatchOrFinallyBlock(tryBody) {
+    val kind = "Syntax"
+    val msg =
+      hl"""|A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting
+           |its body in a block; no exceptions are handled.""".stripMargin
+  }
+}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala b/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala
new file mode 100644
index 000000000000..4aa24c440949
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala
@@ -0,0 +1,47 @@
+package dotty.tools
+package dotc
+package reporting
+package diagnostic
+
+import dotc.core._
+import Contexts.Context, Decorators._, Symbols._
+import dotc.printing.SyntaxHighlighting._
+import util.{SourcePosition, NoSourcePosition}
+
+object tpe {
+  import dotc.ast.Trees._
+  import dotc.ast.untpd
+
+  class DuplicateBind(
+    bind: untpd.Bind,
+    tree: untpd.CaseDef
+  )(implicit ctx: Context) extends MessageCreator {
+    val kind = "Naming"
+
+    val msg =
+      em"duplicate pattern variable: `${bind.name}`"
+
+    val explanation = {
+      val pat = tree.pat.show
+      val guard = tree.guard match {
+        case untpd.EmptyTree => ""
+        case guard => s"if ${guard.show}"
+      }
+
+      val body = tree.body match {
+        case Block(Nil, untpd.EmptyTree) => ""
+        case body => s" ${body.show}"
+      }
+
+      val caseDef = s"case $pat$guard => $body"
+
+      hl"""|Explanation
+           |===========
+           |For each ${"case"} bound variable names  have to be unique. In:
+           |
+           |$caseDef
+           |
+           |`${bind.name}` is not unique. Rename one of the bound variables!""".stripMargin
+    }
+  }
+}
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 6fddd928bde9..32d5e0d96a4c 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -38,7 +38,6 @@ import NavigateAST._
 import transform.SymUtils._
 import language.implicitConversions
 import printing.SyntaxHighlighting._
-import reporting.ErrorMessages._
 
 object Typer {
 
@@ -66,7 +65,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
   import tpd.{cpy => _, _}
   import untpd.cpy
   import Dynamic.isDynamicMethod
-  import reporting.ErrorMessages.Type._
+  import reporting.diagnostic.tpe._
 
   /** A temporary data item valid for a single typed ident:
    *  The set of all root import symbols that have been
@@ -848,7 +847,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         super.transform(trt.withType(elimWildcardSym(trt.tpe))) match {
           case b: Bind =>
             if (ctx.scope.lookup(b.name) == NoSymbol) ctx.enter(b.symbol)
-            else ctx.explainError(DuplicateBind(b, tree), b.pos)
+            else ctx.explainError(new DuplicateBind(b, tree), b.pos)
             b.symbol.info = elimWildcardSym(b.symbol.info)
             b
           case t => t

From 15dfb56d63a893c5c1e34a8566004085a617c28b Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 22:05:14 +0200
Subject: [PATCH 17/53] Add coloring util

---
 .../tools/dotc/printing/Highlighting.scala    | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 src/dotty/tools/dotc/printing/Highlighting.scala

diff --git a/src/dotty/tools/dotc/printing/Highlighting.scala b/src/dotty/tools/dotc/printing/Highlighting.scala
new file mode 100644
index 000000000000..a496976a1e6a
--- /dev/null
+++ b/src/dotty/tools/dotc/printing/Highlighting.scala
@@ -0,0 +1,60 @@
+package dotty.tools
+package dotc
+package printing
+
+import scala.collection.mutable
+
+object Highlighting {
+
+  implicit def colorToString(c: Color): String = c.toString
+  implicit def cbufToString(cb: ColorBuffer): String = cb.toString
+
+  abstract class Color(private val color: String) {
+    def text: String
+
+    override def toString = color + text + Console.RESET
+
+    def +(other: Color): ColorBuffer =
+      new ColorBuffer(this) + other
+
+    def +(other: String): ColorBuffer =
+      new ColorBuffer(this) + other
+  }
+
+  case class ColorBuffer(color: Color) {
+    val buffer = new mutable.ListBuffer[String]
+
+    buffer += color.toString
+
+    def +(color: Color): ColorBuffer = {
+      buffer += color.toString
+      this
+    }
+
+    def +(str: String): ColorBuffer = {
+      buffer += str
+      this
+    }
+
+    override def toString =
+      buffer.mkString
+  }
+
+  case class Red(text: String) extends Color(Console.RED)
+  case class Blue(text: String) extends Color(Console.BLUE)
+  case class Cyan(text: String) extends Color(Console.CYAN)
+  case class Black(text: String) extends Color(Console.BLACK)
+  case class Green(text: String) extends Color(Console.GREEN)
+  case class White(text: String) extends Color(Console.WHITE)
+  case class Yellow(text: String) extends Color(Console.YELLOW)
+  case class Magenta(text: String) extends Color(Console.MAGENTA)
+
+  case class RedB(text: String) extends Color(Console.RED_B)
+  case class BlueB(text: String) extends Color(Console.BLUE_B)
+  case class CyanB(text: String) extends Color(Console.CYAN_B)
+  case class BlackB(text: String) extends Color(Console.BLACK_B)
+  case class GreenB(text: String) extends Color(Console.GREEN_B)
+  case class WhiteB(text: String) extends Color(Console.WHITE_B)
+  case class YellowB(text: String) extends Color(Console.YELLOW_B)
+  case class MagentaB(text: String) extends Color(Console.MAGENTA_B)
+}

From 30b54109e3f535b417249057c2a548808082e06b Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 22:07:36 +0200
Subject: [PATCH 18/53] Factor out explanation header to Reporter

---
 .../dotc/reporting/ConsoleReporter.scala      | 36 +++++++++++++------
 .../dotc/reporting/FancyConsoleReporter.scala | 31 +++++++++++++---
 src/dotty/tools/dotc/reporting/Reporter.scala | 12 ++-----
 .../dotc/reporting/diagnostic/Message.scala   | 10 ++++++
 .../reporting/diagnostic/MessageCreator.scala | 10 ------
 .../dotc/reporting/diagnostic/syntax.scala    |  4 +--
 .../tools/dotc/reporting/diagnostic/tpe.scala | 16 ++++++---
 7 files changed, 77 insertions(+), 42 deletions(-)

diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 3a4f60aebbde..a0081332801a 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -20,6 +20,8 @@ class ConsoleReporter(
     writer: PrintWriter = new PrintWriter(Console.err, true))
   extends Reporter with UniqueMessagePositions with HideNonSensicalMessages {
 
+  import Message._
+
   /** maximal number of error messages to be printed */
   protected def ErrorLimit = 100
 
@@ -42,17 +44,29 @@ class ConsoleReporter(
     }
   }
 
-  override def doReport(m: Message)(implicit ctx: Context): Unit = m match {
-    case m: Error =>
-      printMessageAndPos(m.message, m.pos, m.kind)
-      if (ctx.settings.prompt.value) displayPrompt()
-    case m: ConditionalWarning if !m.enablingOption.value =>
-    case m: MigrationWarning =>
-      printMessageAndPos(m.message, m.pos, m.kind)
-    case m: Warning =>
-      printMessageAndPos(m.message, m.pos, m.kind)
-    case _ =>
-      printMessageAndPos(m.message, m.pos, m.kind)
+  def printExplanation(m: Message): Unit =
+    printMessage(
+      s"""|
+          |Explanation
+          |===========
+          |${m.explanation}""".stripMargin
+    )
+
+  override def doReport(m: Message)(implicit ctx: Context): Unit = {
+    m match {
+      case m: Error =>
+        printMessageAndPos(m.message, m.pos, m.kind)
+        if (ctx.settings.prompt.value) displayPrompt()
+      case m: ConditionalWarning if !m.enablingOption.value =>
+      case m: MigrationWarning =>
+        printMessageAndPos(m.message, m.pos, m.kind)
+      case m: Warning =>
+        printMessageAndPos(m.message, m.pos, m.kind)
+      case _ =>
+        printMessageAndPos(m.message, m.pos, m.kind)
+    }
+
+    if (ctx.shouldExplain(m)) printExplanation(m)
   }
 
   def displayPrompt(): Unit = {
diff --git a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
index 80f15a4b0c27..3fc9ab4733b2 100644
--- a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
@@ -9,6 +9,8 @@ import Reporter._
 import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
 import printing.SyntaxHighlighting._
+import printing.Highlighting._
+import diagnostic.Message
 
 /**
  * This class implements a more Fancy version (with colors!) of the regular
@@ -56,7 +58,7 @@ class FancyConsoleReporter(
   }
 
   def posStr(pos: SourcePosition, kind: String)(implicit ctx: Context) =
-    if (pos.exists) {
+    if (pos.exists) Blue({
       val file = pos.source.file.toString
 
       val outer = if (pos.outer.exists) {
@@ -64,12 +66,11 @@ class FancyConsoleReporter(
         printStr(pos.outer) + "\n" + "-" * ctx.settings.pageWidth.value
       } else ""
 
-      val prefix = s"${Console.CYAN}-- $kind: $file "
+      val prefix = s"-- $kind: $file "
       prefix +
       ("-" * math.max(ctx.settings.pageWidth.value - prefix.replaceAll("\u001B\\[[;\\d]*m", "").length, 0)) +
-      "\n" + outer + NoColor
-    }
-    else ""
+      "\n" + outer
+    }).toString else ""
 
   /** Prints the message with the given position indication. */
   override def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
@@ -82,4 +83,24 @@ class FancyConsoleReporter(
       printMessage(List(src, marker, err).mkString("\n"))
     } else printMessage(msg)
   }
+
+  override def printExplanation(m: Message): Unit =
+    printMessage(
+      s"""|
+          |${Blue("Explanation")}
+          |${Blue("===========")}
+          |${m.explanation}""".stripMargin
+    )
+
+
+  override def summary: String = {
+    val b = new mutable.ListBuffer[String]
+    if (warningCount > 0)
+      b += countString(warningCount, Yellow("warning")) + " found"
+    if (errorCount > 0)
+      b += countString(errorCount, Red("error")) + " found"
+    for ((settingName, count) <- unreportedWarnings)
+      b += s"there were $count ${settingName.tail} ${Yellow("warning(s)")}; re-run with $settingName for details"
+    b.mkString("\n")
+  }
 }
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index 5c3dcccb7bf1..fe226b28494e 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -75,11 +75,8 @@ trait Reporting { this: Context =>
   def warning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(new Warning(msg, pos))
 
-  def explainWarning(msg: => MessageCreator, pos: SourcePosition = NoSourcePosition): Unit = {
+  def explainWarning(msg: => MessageCreator, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(msg.warning(pos))
-    if (this.shouldExplain(msg))
-      reporter.report(new Info(msg.explanation, NoSourcePosition))
-  }
 
   def strictWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     if (this.settings.strict.value) error(msg, pos)
@@ -90,11 +87,8 @@ trait Reporting { this: Context =>
     reporter.report(new Error(msg, pos))
   }
 
-  def explainError(msg: => MessageCreator, pos: SourcePosition = NoSourcePosition): Unit = {
+  def explainError(msg: => MessageCreator, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(msg.error(pos))
-    if (this.shouldExplain(msg))
-      reporter.report(new Info(msg.explanation, NoSourcePosition))
-  }
 
   def errorOrMigrationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     if (ctx.scala2Mode) migrationWarning(msg, pos) else error(msg, pos)
@@ -271,7 +265,7 @@ abstract class Reporter extends interfaces.ReporterResult {
   }
 
   /** Returns a string meaning "n elements". */
-  private def countString(n: Int, elements: String): String = n match {
+  protected def countString(n: Int, elements: String): String = n match {
     case 0 => "no " + elements + "s"
     case 1 => "one " + elements
     case 2 => "two " + elements + "s"
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index d7cfa2e2b3e4..b3c19820fa08 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -11,6 +11,16 @@ import java.util.Optional
 object Message {
   val nonSensicalStartTag = "<nonsensical>"
   val nonSensicalEndTag = "</nonsensical>"
+
+  implicit class MessageContext(val c: Context) extends AnyVal {
+    def shouldExplain(msg: Message): Boolean = {
+      implicit val ctx: Context = c
+      msg.explanation match {
+        case "" => false
+        case _ => ctx.settings.explain.value
+      }
+    }
+  }
 }
 
 class Message(
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
index d74099f4f92e..4be325b6383f 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
@@ -7,16 +7,6 @@ import util.{SourcePosition, NoSourcePosition}
 import core.Contexts.Context
 
 object MessageCreator {
-  implicit class DiagnosticContext(val c: Context) extends AnyVal {
-    def shouldExplain(msg: MessageCreator): Boolean = {
-      implicit val ctx: Context = c
-      msg match {
-        case NoExplanation(_) => false
-        case _ => ctx.settings.explain.value
-      }
-    }
-  }
-
   implicit def toNoExplanation(str: String) =
     new NoExplanation(str)
 }
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala b/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
index 675cacbedaf4..b9a662c7ddf5 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
@@ -29,9 +29,7 @@ object syntax {
             |  // perform your cleanup here!
             |}""".stripMargin
 
-      hl"""|Explanation:
-           |============
-           |A ${"try"} expression should be followed by some mechanism to handle any exceptions
+      hl"""|A ${"try"} expression should be followed by some mechanism to handle any exceptions
            |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
            |on any expected exceptions. For example:
            |
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala b/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala
index 4aa24c440949..ee221f80d9c9 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala
@@ -4,7 +4,7 @@ package reporting
 package diagnostic
 
 import dotc.core._
-import Contexts.Context, Decorators._, Symbols._
+import Contexts.Context, Decorators._, Symbols._, Names._
 import dotc.printing.SyntaxHighlighting._
 import util.{SourcePosition, NoSourcePosition}
 
@@ -35,13 +35,21 @@ object tpe {
 
       val caseDef = s"case $pat$guard => $body"
 
-      hl"""|Explanation
-           |===========
-           |For each ${"case"} bound variable names  have to be unique. In:
+      hl"""|For each ${"case"} bound variable names  have to be unique. In:
            |
            |$caseDef
            |
            |`${bind.name}` is not unique. Rename one of the bound variables!""".stripMargin
     }
   }
+
+  class MissingIdent(tree: untpd.Ident, treeKind: String, name: Name)(implicit ctx: Context) extends MessageCreator {
+    val kind = "Missing identifier"
+    val msg = em"not found: $treeKind$name"
+
+    val explanation = {
+      hl"""|An identifier for `${name.show}` is missing. This means that something
+           |has either been misspelt or you're forgetting an import""".stripMargin
+    }
+  }
 }

From 5c243778279d8b258d7b1d34dd5146dff07eb437 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 22:08:15 +0200
Subject: [PATCH 19/53] Add `MissingIdent` message to `Typer`

---
 src/dotty/tools/dotc/typer/Typer.scala | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 32d5e0d96a4c..b29254b8924f 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -65,6 +65,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
   import tpd.{cpy => _, _}
   import untpd.cpy
   import Dynamic.isDynamicMethod
+  import reporting.diagnostic.MessageCreator
   import reporting.diagnostic.tpe._
 
   /** A temporary data item valid for a single typed ident:
@@ -98,7 +99,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
     /** Method is necessary because error messages need to bind to
      *  to typedIdent's context which is lost in nested calls to findRef
      */
-    def error(msg: => String, pos: Position) = ctx.error(msg, pos)
+    def error(msg: => MessageCreator, pos: Position) = ctx.explainError(msg, pos)
 
     /** Is this import a root import that has been shadowed by an explicit
      *  import in the same program?
@@ -330,7 +331,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
       if (rawType.exists)
         ensureAccessible(rawType, superAccess = false, tree.pos)
       else {
-        error(em"not found: $kind$name", tree.pos)
+        error(new MissingIdent(tree, kind, name), tree.pos)
         ErrorType
       }
 

From 787a2ceec02fe07fbb9efee673d3abb7cac2969e Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 16 Sep 2016 22:28:27 +0200
Subject: [PATCH 20/53] Add modifiers to highlighting

---
 src/dotty/tools/dotc/Compiler.scala           |  4 --
 src/dotty/tools/dotc/Driver.scala             |  6 +-
 .../tools/dotc/printing/Highlighting.scala    | 70 +++++++++++--------
 .../dotc/reporting/ConsoleReporter.scala      |  2 +-
 .../reporting/diagnostic/MessageCreator.scala |  2 +-
 .../tools/dotc/typer/ErrorReporting.scala     |  6 +-
 test/dotc/tests.scala                         |  3 +-
 test/test/CompilerTest.scala                  | 11 +--
 test/test/OtherEntryPointsTest.scala          |  3 +-
 tests/repl/errmsgs.check                      | 48 ++++++-------
 tests/repl/imports.check                      | 12 ++--
 11 files changed, 89 insertions(+), 78 deletions(-)

diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index d6e3cc89b0b5..ea6254f5b802 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -140,10 +140,6 @@ class Compiler {
       .setTyper(new Typer)
       .setMode(Mode.ImplicitsEnabled)
       .setTyperState(new MutableTyperState(ctx.typerState, ctx.typerState.reporter, isCommittable = true))
-      .setReporter(
-        if (ctx.settings.color.value == "never") new ConsoleReporter()
-        else new FancyConsoleReporter()
-      )
     ctx.initialize()(start) // re-initialize the base context with start
     def addImport(ctx: Context, refFn: () => TermRef) =
       ctx.fresh.setImportInfo(ImportInfo.rootImport(refFn)(ctx))
diff --git a/src/dotty/tools/dotc/Driver.scala b/src/dotty/tools/dotc/Driver.scala
index f54a23ad2451..b2dc18d2a35e 100644
--- a/src/dotty/tools/dotc/Driver.scala
+++ b/src/dotty/tools/dotc/Driver.scala
@@ -22,7 +22,11 @@ abstract class Driver extends DotClass {
   protected def doCompile(compiler: Compiler, fileNames: List[String])(implicit ctx: Context): Reporter =
     if (fileNames.nonEmpty)
       try {
-        val run = compiler.newRun
+        val fresh = ctx.fresh.setReporter {
+          if (ctx.settings.color.value == "never") new ConsoleReporter()
+          else new FancyConsoleReporter()
+        }
+        val run = compiler.newRun(fresh)
         run.compile(fileNames)
         run.printSummary()
       }
diff --git a/src/dotty/tools/dotc/printing/Highlighting.scala b/src/dotty/tools/dotc/printing/Highlighting.scala
index a496976a1e6a..75f83bf29cd5 100644
--- a/src/dotty/tools/dotc/printing/Highlighting.scala
+++ b/src/dotty/tools/dotc/printing/Highlighting.scala
@@ -6,33 +6,38 @@ import scala.collection.mutable
 
 object Highlighting {
 
-  implicit def colorToString(c: Color): String = c.toString
-  implicit def cbufToString(cb: ColorBuffer): String = cb.toString
+  implicit def highlightToString(h: Highlight): String = h.toString
+  implicit def hbufToString(hb: HighlightBuffer): String = hb.toString
 
-  abstract class Color(private val color: String) {
+  abstract class Highlight(private val highlight: String) {
     def text: String
 
-    override def toString = color + text + Console.RESET
+    override def toString = highlight + text + Console.RESET
 
-    def +(other: Color): ColorBuffer =
-      new ColorBuffer(this) + other
+    def +(other: Highlight): HighlightBuffer =
+      new HighlightBuffer(this) + other
 
-    def +(other: String): ColorBuffer =
-      new ColorBuffer(this) + other
+    def +(other: String): HighlightBuffer =
+      new HighlightBuffer(this) + other
   }
 
-  case class ColorBuffer(color: Color) {
+  abstract class Modifier(private val mod: String, text: String) extends Highlight(Console.RESET) {
+    override def toString =
+      mod + super.toString
+  }
+
+  case class HighlightBuffer(hl: Highlight) {
     val buffer = new mutable.ListBuffer[String]
 
-    buffer += color.toString
+    buffer += hl.toString
 
-    def +(color: Color): ColorBuffer = {
-      buffer += color.toString
+    def +(other: Highlight): HighlightBuffer = {
+      buffer += other.toString
       this
     }
 
-    def +(str: String): ColorBuffer = {
-      buffer += str
+    def +(other: String): HighlightBuffer = {
+      buffer += other
       this
     }
 
@@ -40,21 +45,24 @@ object Highlighting {
       buffer.mkString
   }
 
-  case class Red(text: String) extends Color(Console.RED)
-  case class Blue(text: String) extends Color(Console.BLUE)
-  case class Cyan(text: String) extends Color(Console.CYAN)
-  case class Black(text: String) extends Color(Console.BLACK)
-  case class Green(text: String) extends Color(Console.GREEN)
-  case class White(text: String) extends Color(Console.WHITE)
-  case class Yellow(text: String) extends Color(Console.YELLOW)
-  case class Magenta(text: String) extends Color(Console.MAGENTA)
-
-  case class RedB(text: String) extends Color(Console.RED_B)
-  case class BlueB(text: String) extends Color(Console.BLUE_B)
-  case class CyanB(text: String) extends Color(Console.CYAN_B)
-  case class BlackB(text: String) extends Color(Console.BLACK_B)
-  case class GreenB(text: String) extends Color(Console.GREEN_B)
-  case class WhiteB(text: String) extends Color(Console.WHITE_B)
-  case class YellowB(text: String) extends Color(Console.YELLOW_B)
-  case class MagentaB(text: String) extends Color(Console.MAGENTA_B)
+  case class Red(text: String) extends Highlight(Console.RED)
+  case class Blue(text: String) extends Highlight(Console.BLUE)
+  case class Cyan(text: String) extends Highlight(Console.CYAN)
+  case class Black(text: String) extends Highlight(Console.BLACK)
+  case class Green(text: String) extends Highlight(Console.GREEN)
+  case class White(text: String) extends Highlight(Console.WHITE)
+  case class Yellow(text: String) extends Highlight(Console.YELLOW)
+  case class Magenta(text: String) extends Highlight(Console.MAGENTA)
+
+  case class RedB(text: String) extends Highlight(Console.RED_B)
+  case class BlueB(text: String) extends Highlight(Console.BLUE_B)
+  case class CyanB(text: String) extends Highlight(Console.CYAN_B)
+  case class BlackB(text: String) extends Highlight(Console.BLACK_B)
+  case class GreenB(text: String) extends Highlight(Console.GREEN_B)
+  case class WhiteB(text: String) extends Highlight(Console.WHITE_B)
+  case class YellowB(text: String) extends Highlight(Console.YELLOW_B)
+  case class MagentaB(text: String) extends Highlight(Console.MAGENTA_B)
+
+  case class Bold(text: String) extends Modifier(Console.BOLD, text)
+  case class Underlined(text: String) extends Modifier(Console.UNDERLINED, text)
 }
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index a0081332801a..b532d05c22e7 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -37,7 +37,7 @@ class ConsoleReporter(
   /** Prints the message with the given position indication. */
   def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
     val posStr = if (pos.exists) s"$pos: " else ""
-    printMessage(posStr + kind + msg)
+    printMessage(s"${posStr}$kind: $msg")
     if (pos.exists) {
       printSourceLine(pos)
       printColumnMarker(pos)
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
index 4be325b6383f..99ccca4cc7b6 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
@@ -7,7 +7,7 @@ import util.{SourcePosition, NoSourcePosition}
 import core.Contexts.Context
 
 object MessageCreator {
-  implicit def toNoExplanation(str: String) =
+  implicit def toNoExplanation(str: String): MessageCreator =
     new NoExplanation(str)
 }
 
diff --git a/src/dotty/tools/dotc/typer/ErrorReporting.scala b/src/dotty/tools/dotc/typer/ErrorReporting.scala
index c8e76aa97b58..43c09351050b 100644
--- a/src/dotty/tools/dotc/typer/ErrorReporting.scala
+++ b/src/dotty/tools/dotc/typer/ErrorReporting.scala
@@ -131,9 +131,9 @@ object ErrorReporting {
       val found1 = reported(found)
       reported.setVariance(-1)
       val expected1 = reported(expected)
-      ex"""type mismatch:
-          | found   : $found1
-          | required: $expected1""" + whyNoMatchStr(found, expected)
+      ex"""|type mismatch:
+           |found:    $found1
+           |required: $expected1""".stripMargin + whyNoMatchStr(found, expected)
     }
 
     /** Format `raw` implicitNotFound argument, replacing all
diff --git a/test/dotc/tests.scala b/test/dotc/tests.scala
index f161fefe3b4b..39e5f5ead4c4 100644
--- a/test/dotc/tests.scala
+++ b/test/dotc/tests.scala
@@ -23,7 +23,8 @@ class tests extends CompilerTest {
   val defaultOutputDir = "./out/"
 
   implicit val defaultOptions = noCheckOptions ++ List(
-      "-Yno-deep-subtypes", "-Yno-double-bindings", "-Yforce-sbt-phases", "-d", defaultOutputDir) ++ {
+      "-Yno-deep-subtypes", "-Yno-double-bindings", "-Yforce-sbt-phases", "-color:never",
+      "-d", defaultOutputDir) ++ {
     if (isRunByJenkins) List("-Ycheck:tailrec,resolveSuper,mixin,restoreScopes,labelDef") // should be Ycheck:all, but #725
     else List("-Ycheck:tailrec,resolveSuper,mixin,restoreScopes,labelDef")
   }
diff --git a/test/test/CompilerTest.scala b/test/test/CompilerTest.scala
index dea6a30b1432..942948f085a1 100644
--- a/test/test/CompilerTest.scala
+++ b/test/test/CompilerTest.scala
@@ -5,6 +5,7 @@ import dotty.partest.DPConfig
 import dotty.tools.dotc.{Main, Bench, Driver}
 import dotty.tools.dotc.interfaces.Diagnostic.ERROR
 import dotty.tools.dotc.reporting._
+import diagnostic.Message
 import dotty.tools.dotc.util.SourcePosition
 import dotty.tools.dotc.config.CompilerCommand
 import dotty.tools.io.PlainFile
@@ -237,13 +238,13 @@ abstract class CompilerTest {
     val storeReporter = new Reporter with UniqueMessagePositions with HideNonSensicalMessages {
       private val consoleReporter = new ConsoleReporter()
       private val innerStoreReporter = new StoreReporter(consoleReporter)
-      def doReport(d: Diagnostic)(implicit ctx: Context): Unit = {
-        if (d.level == ERROR) {
+      def doReport(m: Message)(implicit ctx: Context): Unit = {
+        if (m.level == ERROR) {
           innerStoreReporter.flush()
-          consoleReporter.doReport(d)
+          consoleReporter.doReport(m)
         }
-        else if (errorCount > 0) consoleReporter.doReport(d)
-        else innerStoreReporter.doReport(d)
+        else if (errorCount > 0) consoleReporter.doReport(m)
+        else innerStoreReporter.doReport(m)
       }
     }
     val reporter = processor.process(allArgs, storeReporter)
diff --git a/test/test/OtherEntryPointsTest.scala b/test/test/OtherEntryPointsTest.scala
index 5f8681d3864c..824034055632 100644
--- a/test/test/OtherEntryPointsTest.scala
+++ b/test/test/OtherEntryPointsTest.scala
@@ -5,6 +5,7 @@ import org.junit.Assert._
 import dotty.tools.dotc.Main
 import dotty.tools.dotc.interfaces.{CompilerCallback, SourceFile}
 import dotty.tools.dotc.reporting._
+import dotty.tools.dotc.reporting.diagnostic.Message
 import dotty.tools.dotc.core.Contexts._
 import java.io.File
 import scala.collection.mutable.ListBuffer
@@ -50,7 +51,7 @@ class OtherEntryPointsTest {
   private class CustomReporter extends Reporter
       with UniqueMessagePositions
       with HideNonSensicalMessages {
-    def doReport(d: Diagnostic)(implicit ctx: Context): Unit = {
+    def doReport(m: Message)(implicit ctx: Context): Unit = {
     }
   }
 
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index d8e863a28612..e32e72d1f7b0 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -1,41 +1,41 @@
 scala> class Inv[T](x: T)
 defined class Inv
 scala> val x: List[String] = List(1)
-<console>:4: error: type mismatch:
- found   : Int(1)
- required: String
+<console>:4: Error: type mismatch:
+found:    Int(1)
+required: String
 val x: List[String] = List(1)
                            ^
 scala> val y: List[List[String]] = List(List(1))
-<console>:4: error: type mismatch:
- found   : Int(1)
- required: String
+<console>:4: Error: type mismatch:
+found:    Int(1)
+required: String
 val y: List[List[String]] = List(List(1))
                                       ^
 scala> val z: (List[String], List[Int]) = (List(1), List("a"))
-<console>:4: error: type mismatch:
- found   : Int(1)
- required: String
+<console>:4: Error: type mismatch:
+found:    Int(1)
+required: String
 val z: (List[String], List[Int]) = (List(1), List("a"))
                                          ^
-<console>:4: error: type mismatch:
- found   : String("a")
- required: Int
+<console>:4: Error: type mismatch:
+found:    String("a")
+required: Int
 val z: (List[String], List[Int]) = (List(1), List("a"))
                                                   ^
 scala> val a: Inv[String] = new Inv(new Inv(1))
-<console>:5: error: type mismatch:
- found   : Inv[T]
- required: String
+<console>:5: Error: type mismatch:
+found:    Inv[T]
+required: String
 
 where  T  is a type variable with constraint >: Int(1)
 
 val a: Inv[String] = new Inv(new Inv(1))
                                  ^
 scala> val b: Inv[String] = new Inv(1)
-<console>:5: error: type mismatch:
- found   : Int(1)
- required: String
+<console>:5: Error: type mismatch:
+found:    Int(1)
+required: String
 val b: Inv[String] = new Inv(1)
                              ^
 scala> abstract class C {
@@ -53,18 +53,18 @@ scala> abstract class C {
              }
            }
          }
-<console>:9: error: type mismatch:
- found   : C.this.T(C.this.x)
- required: T'
+<console>:9: Error: type mismatch:
+found:    C.this.T(C.this.x)
+required: T'
 
 where  T   is a type in class C
        T'  is a type in the initalizer of value s which is an alias of String
 
       var y: T = x
                  ^
-<console>:13: error: type mismatch:
- found   : T(y)
- required: T'
+<console>:13: Error: type mismatch:
+found:    T(y)
+required: T'
 
 where  T   is a type in the initalizer of value s which is an alias of String
        T'  is a type in method f which is an alias of Int
diff --git a/tests/repl/imports.check b/tests/repl/imports.check
index 3a7e9341efa2..50b7a93d7f03 100644
--- a/tests/repl/imports.check
+++ b/tests/repl/imports.check
@@ -7,14 +7,14 @@ defined module o
 scala> import o._
 import o._
 scala> buf += xs
-<console>:11: error: type mismatch:
- found   : scala.collection.immutable.List[Int](o.xs)
- required: String
+<console>:11: Error: type mismatch:
+found:    scala.collection.immutable.List[Int](o.xs)
+required: String
 buf += xs
        ^
-<console>:11: error: type mismatch:
- found   : String
- required: scala.collection.mutable.ListBuffer[Int]
+<console>:11: Error: type mismatch:
+found:    String
+required: scala.collection.mutable.ListBuffer[Int]
 buf += xs
 ^
 scala> buf ++= xs

From 628b7f317756ce2c366359a7399b8dda9d0190b7 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Sun, 18 Sep 2016 08:45:29 +0200
Subject: [PATCH 21/53] Make `FancyConsoleReporter` and `Highlighting` obey
 color setting

Fancy console reporter and the string interpolator for highlighting now
obey the color setting - this means that the next step towards unifying
the reporters is to make sure the tests work with
`FancyConsoleReporter` under the `-color:never` flag.
---
 src/dotty/tools/dotc/Driver.scala             |  6 +-
 .../tools/dotc/printing/Highlighting.scala    | 33 +++++++----
 .../dotc/printing/SyntaxHighlighting.scala    | 13 ++++-
 .../dotc/reporting/ConsoleReporter.scala      |  2 +-
 .../dotc/reporting/FancyConsoleReporter.scala | 55 +++++++++----------
 src/dotty/tools/dotc/reporting/Reporter.scala |  2 +-
 6 files changed, 64 insertions(+), 47 deletions(-)

diff --git a/src/dotty/tools/dotc/Driver.scala b/src/dotty/tools/dotc/Driver.scala
index b2dc18d2a35e..f54a23ad2451 100644
--- a/src/dotty/tools/dotc/Driver.scala
+++ b/src/dotty/tools/dotc/Driver.scala
@@ -22,11 +22,7 @@ abstract class Driver extends DotClass {
   protected def doCompile(compiler: Compiler, fileNames: List[String])(implicit ctx: Context): Reporter =
     if (fileNames.nonEmpty)
       try {
-        val fresh = ctx.fresh.setReporter {
-          if (ctx.settings.color.value == "never") new ConsoleReporter()
-          else new FancyConsoleReporter()
-        }
-        val run = compiler.newRun(fresh)
+        val run = compiler.newRun
         run.compile(fileNames)
         run.printSummary()
       }
diff --git a/src/dotty/tools/dotc/printing/Highlighting.scala b/src/dotty/tools/dotc/printing/Highlighting.scala
index 75f83bf29cd5..13e55722fa34 100644
--- a/src/dotty/tools/dotc/printing/Highlighting.scala
+++ b/src/dotty/tools/dotc/printing/Highlighting.scala
@@ -3,36 +3,47 @@ package dotc
 package printing
 
 import scala.collection.mutable
+import core.Contexts.Context
 
 object Highlighting {
 
-  implicit def highlightToString(h: Highlight): String = h.toString
-  implicit def hbufToString(hb: HighlightBuffer): String = hb.toString
+  implicit def highlightShow(h: Highlight)(implicit ctx: Context): String =
+    h.show
+  implicit def highlightToString(h: Highlight): String =
+    h.toString
+  implicit def hbufToString(hb: HighlightBuffer): String =
+    hb.toString
 
   abstract class Highlight(private val highlight: String) {
     def text: String
 
-    override def toString = highlight + text + Console.RESET
+    def show(implicit ctx: Context) =
+      if (ctx.settings.color.value == "never") text
+      else highlight + text + Console.RESET
 
-    def +(other: Highlight): HighlightBuffer =
+    override def toString =
+      highlight + text + Console.RESET
+
+    def +(other: Highlight)(implicit ctx: Context): HighlightBuffer =
       new HighlightBuffer(this) + other
 
-    def +(other: String): HighlightBuffer =
+    def +(other: String)(implicit ctx: Context): HighlightBuffer =
       new HighlightBuffer(this) + other
   }
 
   abstract class Modifier(private val mod: String, text: String) extends Highlight(Console.RESET) {
-    override def toString =
-      mod + super.toString
+    override def show(implicit ctx: Context) =
+      if (ctx.settings.color.value == "never") ""
+      else mod + super.show
   }
 
-  case class HighlightBuffer(hl: Highlight) {
+  case class HighlightBuffer(hl: Highlight)(implicit ctx: Context) {
     val buffer = new mutable.ListBuffer[String]
 
-    buffer += hl.toString
+    buffer += hl.show
 
     def +(other: Highlight): HighlightBuffer = {
-      buffer += other.toString
+      buffer += other.show
       this
     }
 
@@ -45,6 +56,8 @@ object Highlighting {
       buffer.mkString
   }
 
+  case class NoColor(text: String) extends Highlight(Console.RESET)
+
   case class Red(text: String) extends Highlight(Console.RED)
   case class Blue(text: String) extends Highlight(Console.BLUE)
   case class Cyan(text: String) extends Highlight(Console.CYAN)
diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index d94f6796d8d7..95e59ccf347e 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -6,14 +6,23 @@ import parsing.Tokens._
 import scala.annotation.switch
 import scala.collection.mutable.StringBuilder
 import core.Contexts.Context
+import Highlighting.{Highlight, HighlightBuffer}
 
 /** This object provides functions for syntax highlighting in the REPL */
 object SyntaxHighlighting {
 
   implicit class SyntaxFormatting(val sc: StringContext) extends AnyVal {
     def hl(args: Any*)(implicit ctx: Context): String =
-      if (ctx.settings.color.value == "never") sc.s(args: _*)
-      else sc.s(args.map(x => new String(apply(x.toString).toArray)): _*)
+      sc.s(args.map ({
+        case hl: Highlight =>
+          hl.show
+        case hb: HighlightBuffer =>
+          hb.toString
+        case x if ctx.settings.color.value != "never" =>
+          new String(apply(x.toString).toArray)
+        case x =>
+          x.toString
+      }): _*)
   }
 
   val NoColor         = Console.RESET
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index b532d05c22e7..1ae6a1135035 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -44,7 +44,7 @@ class ConsoleReporter(
     }
   }
 
-  def printExplanation(m: Message): Unit =
+  def printExplanation(m: Message)(implicit ctx: Context): Unit =
     printMessage(
       s"""|
           |Explanation
diff --git a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
index 3fc9ab4733b2..d69396f5f942 100644
--- a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
@@ -21,29 +21,29 @@ class FancyConsoleReporter(
   writer: PrintWriter = new PrintWriter(Console.err, true)
 ) extends ConsoleReporter(reader, writer) {
 
+  def stripColor(str: String): String =
+    str.replaceAll("\u001B\\[[;\\d]*m", "")
+
   def sourceLine(pos: SourcePosition)(implicit ctx: Context): (String, Int) = {
     val lineNum = s"${pos.line}:"
     (lineNum + hl"${pos.lineContent.stripLineEnd}", lineNum.length)
   }
 
-  def columnMarker(pos: SourcePosition, offset: Int) =
+  def columnMarker(pos: SourcePosition, offset: Int)(implicit ctx: Context) =
     if (pos.startLine == pos.endLine) {
       val whitespace = " " * (pos.column + offset)
       val carets =
-        AnnotationColor +
-        ("^" * math.max(1, pos.endColumn - pos.startColumn)) +
-        NoColor
+        Red("^" * math.max(1, pos.endColumn - pos.startColumn))
 
-      whitespace + carets
+      whitespace + carets.show
     } else {
-      " " * (pos.column + offset) + AnnotationColor + "^" + NoColor
+      Red(" " * (pos.column + offset) + "^").show
     }
 
   def errorMsg(pos: SourcePosition, msg: String, offset: Int)(implicit ctx: Context) = {
     var hasLongLines = false
     val leastWhitespace = msg.lines.foldLeft(Int.MaxValue) { (minPad, line) =>
-      val lineLength =
-        line.replaceAll("\u001B\\[[;\\d]*m", "").length
+      val lineLength = stripColor(line).length
       val padding =
         math.min(math.max(0, ctx.settings.pageWidth.value - offset - lineLength), offset + pos.startColumn)
 
@@ -68,9 +68,9 @@ class FancyConsoleReporter(
 
       val prefix = s"-- $kind: $file "
       prefix +
-      ("-" * math.max(ctx.settings.pageWidth.value - prefix.replaceAll("\u001B\\[[;\\d]*m", "").length, 0)) +
+      ("-" * math.max(ctx.settings.pageWidth.value - stripColor(prefix).length, 0)) +
       "\n" + outer
-    }).toString else ""
+    }).show else ""
 
   /** Prints the message with the given position indication. */
   override def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
@@ -84,23 +84,22 @@ class FancyConsoleReporter(
     } else printMessage(msg)
   }
 
-  override def printExplanation(m: Message): Unit =
-    printMessage(
-      s"""|
-          |${Blue("Explanation")}
-          |${Blue("===========")}
-          |${m.explanation}""".stripMargin
-    )
-
-
-  override def summary: String = {
-    val b = new mutable.ListBuffer[String]
-    if (warningCount > 0)
-      b += countString(warningCount, Yellow("warning")) + " found"
-    if (errorCount > 0)
-      b += countString(errorCount, Red("error")) + " found"
-    for ((settingName, count) <- unreportedWarnings)
-      b += s"there were $count ${settingName.tail} ${Yellow("warning(s)")}; re-run with $settingName for details"
-    b.mkString("\n")
+  override def printExplanation(m: Message)(implicit ctx: Context): Unit = {
+    printMessage(hl"""|
+                      |${Blue("Explanation")}
+                      |${Blue("===========")}""".stripMargin)
+    printMessage(m.explanation)
   }
+
+
+  //override def summary(implicit ctx: Context): String = {
+  //  val b = new mutable.ListBuffer[String]
+  //  if (warningCount > 0)
+  //    b += countString(warningCount, Yellow("warning").show) + " found"
+  //  if (errorCount > 0)
+  //    b += countString(errorCount, Red("error").show) + " found"
+  //  for ((settingName, count) <- unreportedWarnings)
+  //    b += s"there were $count ${settingName.tail} ${Yellow("warning(s)").show}; re-run with $settingName for details"
+  //  b.mkString("\n")
+  //}
 }
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index fe226b28494e..538464daa01b 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -247,7 +247,7 @@ abstract class Reporter extends interfaces.ReporterResult {
 
 
   /** Summary of warnings and errors */
-  def summary: String = {
+  def summary/*(implicit ctx: Context)*/: String = {
     val b = new mutable.ListBuffer[String]
     if (warningCount > 0)
       b += countString(warningCount, "warning") + " found"

From e24289ac19a21c6b3794d02e8fe42766224f173c Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 19 Sep 2016 19:26:16 +0200
Subject: [PATCH 22/53] Make relevant parts of compiler conform to new error
 handling

---
 src/dotty/tools/dotc/parsing/Parsers.scala    |  23 ++-
 .../tools/dotc/printing/Formatting.scala      |   5 +-
 .../dotc/reporting/ConsoleReporter.scala      |  25 ++--
 .../dotc/reporting/FancyConsoleReporter.scala |  18 +--
 .../reporting/HideNonSensicalMessages.scala   |   4 +-
 src/dotty/tools/dotc/reporting/Reporter.scala |  59 ++++----
 .../tools/dotc/reporting/StoreReporter.scala  |   6 +-
 .../dotc/reporting/ThrowingReporter.scala     |   4 +-
 .../reporting/UniqueMessagePositions.scala    |   4 +-
 .../dotc/reporting/diagnostic/Message.scala   |  98 ++++++-------
 .../diagnostic/MessageContainer.scala         |  76 ++++++++++
 .../reporting/diagnostic/MessageCreator.scala |  52 -------
 .../dotc/reporting/diagnostic/messages.scala  | 134 ++++++++++++++++--
 .../dotc/reporting/diagnostic/parser.scala    |   8 --
 .../dotc/reporting/diagnostic/syntax.scala    |  61 --------
 .../tools/dotc/reporting/diagnostic/tpe.scala |  55 -------
 .../tools/dotc/typer/ErrorReporting.scala     |   3 +-
 src/dotty/tools/dotc/typer/Typer.scala        |  12 +-
 test/test/CompilerTest.scala                  |   4 +-
 test/test/OtherEntryPointsTest.scala          |   4 +-
 20 files changed, 317 insertions(+), 338 deletions(-)
 create mode 100644 src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
 delete mode 100644 src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
 delete mode 100644 src/dotty/tools/dotc/reporting/diagnostic/parser.scala
 delete mode 100644 src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
 delete mode 100644 src/dotty/tools/dotc/reporting/diagnostic/tpe.scala

diff --git a/src/dotty/tools/dotc/parsing/Parsers.scala b/src/dotty/tools/dotc/parsing/Parsers.scala
index 1b451ced7b6f..dcd59629832c 100644
--- a/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -27,9 +27,8 @@ import rewrite.Rewrites.patch
 object Parsers {
 
   import ast.untpd._
-  import reporting.diagnostic.MessageCreator
-  import MessageCreator._
-  import reporting.diagnostic.syntax._
+  import reporting.diagnostic.Message
+  import reporting.diagnostic.messages._
 
   case class OpInfo(operand: Tree, operator: Name, offset: Offset)
 
@@ -100,17 +99,17 @@ object Parsers {
     /** Issue an error at given offset if beyond last error offset
       *  and update lastErrorOffset.
       */
-    def syntaxError(expl: MessageCreator, offset: Int = in.offset): Unit =
+    def syntaxError(msg: Message, offset: Int = in.offset): Unit =
       if (offset > lastErrorOffset) {
-        syntaxError(expl, Position(offset))
+        syntaxError(msg, Position(offset))
         lastErrorOffset = in.offset
       }
 
     /** Unconditionally issue an error at given position, without
       *  updating lastErrorOffset.
       */
-    def syntaxError(expl: MessageCreator, pos: Position): Unit =
-      ctx.explainError(expl, source atPos pos)
+    def syntaxError(msg: Message, pos: Position): Unit =
+      ctx.error(msg, source atPos pos)
 
   }
 
@@ -216,20 +215,20 @@ object Parsers {
       }
     }
 
-    def warning(msg: MessageCreator, offset: Int = in.offset) =
-      ctx.explainWarning(msg, source atPos Position(offset))
+    def warning(msg: Message, offset: Int = in.offset) =
+      ctx.warning(msg, source atPos Position(offset))
 
-    def deprecationWarning(msg: String, offset: Int = in.offset) =
+    def deprecationWarning(msg: Message, offset: Int = in.offset) =
       ctx.deprecationWarning(msg, source atPos Position(offset))
 
     /** Issue an error at current offset taht input is incomplete */
-    def incompleteInputError(msg: String) =
+    def incompleteInputError(msg: Message) =
       ctx.incompleteInputError(msg, source atPos Position(in.offset))
 
     /** If at end of file, issue an incompleteInputError.
      *  Otherwise issue a syntax error and skip to next safe point.
      */
-    def syntaxErrorOrIncomplete(msg: String) =
+    def syntaxErrorOrIncomplete(msg: Message) =
       if (in.token == EOF) incompleteInputError(msg)
       else {
         syntaxError(msg)
diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index f1bb57bd5279..b39d5683e0c3 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -8,7 +8,7 @@ import collection.Map
 import Decorators._
 import scala.annotation.switch
 import scala.util.control.NonFatal
-import reporting.diagnostic.Message
+import reporting.diagnostic.MessageContainer
 
 object Formatting {
 
@@ -67,6 +67,7 @@ object Formatting {
    */
   class ErrorMessageFormatter(sc: StringContext) extends StringFormatter(sc) {
     override protected def showArg(arg: Any)(implicit ctx: Context): String = {
+      import MessageContainer._
       def isSensical(arg: Any): Boolean = arg match {
         case tpe: Type =>
           tpe.exists && !tpe.isErroneous
@@ -76,7 +77,7 @@ object Formatting {
       }
       val str = super.showArg(arg)
       if (isSensical(arg)) str
-      else Message.nonSensicalStartTag + str + Message.nonSensicalEndTag
+      else nonSensicalStartTag + str + nonSensicalEndTag
     }
   }
 
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 1ae6a1135035..92eea9fa9de3 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -9,6 +9,7 @@ import Reporter._
 import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
 import diagnostic.Message
+import diagnostic.MessageContainer
 import diagnostic.messages._
 
 /**
@@ -16,11 +17,11 @@ import diagnostic.messages._
  * console.
  */
 class ConsoleReporter(
-    reader: BufferedReader = Console.in,
-    writer: PrintWriter = new PrintWriter(Console.err, true))
-  extends Reporter with UniqueMessagePositions with HideNonSensicalMessages {
+  reader: BufferedReader = Console.in,
+  writer: PrintWriter = new PrintWriter(Console.err, true)
+) extends Reporter with UniqueMessagePositions with HideNonSensicalMessages {
 
-  import Message._
+  import MessageContainer._
 
   /** maximal number of error messages to be printed */
   protected def ErrorLimit = 100
@@ -35,9 +36,9 @@ class ConsoleReporter(
   def printMessage(msg: String): Unit = { writer.print(msg + "\n"); writer.flush() }
 
   /** Prints the message with the given position indication. */
-  def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
+  def printMessageAndPos(msg: Message, pos: SourcePosition, kind: String)(implicit ctx: Context): Unit = {
     val posStr = if (pos.exists) s"$pos: " else ""
-    printMessage(s"${posStr}$kind: $msg")
+    printMessage(s"${posStr}${kind}: ${msg.msg}")
     if (pos.exists) {
       printSourceLine(pos)
       printColumnMarker(pos)
@@ -52,21 +53,21 @@ class ConsoleReporter(
           |${m.explanation}""".stripMargin
     )
 
-  override def doReport(m: Message)(implicit ctx: Context): Unit = {
+  override def doReport(m: MessageContainer)(implicit ctx: Context): Unit = {
     m match {
       case m: Error =>
-        printMessageAndPos(m.message, m.pos, m.kind)
+        printMessageAndPos(m.contained, m.pos, m.kind)
         if (ctx.settings.prompt.value) displayPrompt()
       case m: ConditionalWarning if !m.enablingOption.value =>
       case m: MigrationWarning =>
-        printMessageAndPos(m.message, m.pos, m.kind)
+        printMessageAndPos(m.contained, m.pos, m.kind)
       case m: Warning =>
-        printMessageAndPos(m.message, m.pos, m.kind)
+        printMessageAndPos(m.contained, m.pos, m.kind)
       case _ =>
-        printMessageAndPos(m.message, m.pos, m.kind)
+        printMessageAndPos(m.contained, m.pos, m.kind)
     }
 
-    if (ctx.shouldExplain(m)) printExplanation(m)
+    if (ctx.shouldExplain(m)) printExplanation(m.contained)
   }
 
   def displayPrompt(): Unit = {
diff --git a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
index d69396f5f942..725e69ff85d9 100644
--- a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
@@ -73,15 +73,15 @@ class FancyConsoleReporter(
     }).show else ""
 
   /** Prints the message with the given position indication. */
-  override def printMessageAndPos(msg: String, pos: SourcePosition, kind: String = "")(implicit ctx: Context): Unit = {
+  override def printMessageAndPos(msg: Message, pos: SourcePosition, kind: String)(implicit ctx: Context): Unit = {
     printMessage(posStr(pos, kind))
     if (pos.exists) {
       val (src, offset) = sourceLine(pos)
       val marker = columnMarker(pos, offset)
-      val err = errorMsg(pos, msg, offset)
+      val err = errorMsg(pos, msg.msg, offset)
 
       printMessage(List(src, marker, err).mkString("\n"))
-    } else printMessage(msg)
+    } else printMessage(msg.msg)
   }
 
   override def printExplanation(m: Message)(implicit ctx: Context): Unit = {
@@ -90,16 +90,4 @@ class FancyConsoleReporter(
                       |${Blue("===========")}""".stripMargin)
     printMessage(m.explanation)
   }
-
-
-  //override def summary(implicit ctx: Context): String = {
-  //  val b = new mutable.ListBuffer[String]
-  //  if (warningCount > 0)
-  //    b += countString(warningCount, Yellow("warning").show) + " found"
-  //  if (errorCount > 0)
-  //    b += countString(errorCount, Red("error").show) + " found"
-  //  for ((settingName, count) <- unreportedWarnings)
-  //    b += s"there were $count ${settingName.tail} ${Yellow("warning(s)").show}; re-run with $settingName for details"
-  //  b.mkString("\n")
-  //}
 }
diff --git a/src/dotty/tools/dotc/reporting/HideNonSensicalMessages.scala b/src/dotty/tools/dotc/reporting/HideNonSensicalMessages.scala
index 140777275f54..ba1ab9b33beb 100644
--- a/src/dotty/tools/dotc/reporting/HideNonSensicalMessages.scala
+++ b/src/dotty/tools/dotc/reporting/HideNonSensicalMessages.scala
@@ -3,7 +3,7 @@ package dotc
 package reporting
 
 import core.Contexts.Context
-import diagnostic.Message
+import diagnostic.MessageContainer
 
 /**
  * This trait implements `isHidden` so that we avoid reporting non-sensical messages.
@@ -12,7 +12,7 @@ trait HideNonSensicalMessages extends Reporter {
   /** Hides non-sensical messages, unless we haven't reported any error yet or
    *  `-Yshow-suppressed-errors` is set.
    */
-  override def isHidden(m: Message)(implicit ctx: Context): Boolean =
+  override def isHidden(m: MessageContainer)(implicit ctx: Context): Boolean =
     super.isHidden(m) || {
         m.isNonSensical &&
         hasErrors && // if there are no errors yet, report even if diagnostic is non-sensical
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index 538464daa01b..b969fa8787cd 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -12,13 +12,13 @@ import core.Mode
 import dotty.tools.dotc.core.Symbols.Symbol
 import diagnostic.messages._
 import diagnostic._
-import MessageCreator._
+import Message._
 
 object Reporter {
   /** Convert a SimpleReporter into a real Reporter */
   def fromSimpleReporter(simple: interfaces.SimpleReporter): Reporter =
     new Reporter with UniqueMessagePositions with HideNonSensicalMessages {
-      override def doReport(m: Message)(implicit ctx: Context): Unit = m match {
+      override def doReport(m: MessageContainer)(implicit ctx: Context): Unit = m match {
         case m: ConditionalWarning if !m.enablingOption.value =>
         case _ =>
           simple.report(m)
@@ -37,17 +37,17 @@ trait Reporting { this: Context =>
   def echo(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(new Info(msg, pos, "Info"))
 
-  def deprecationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new DeprecationWarning(msg, pos, "Deprecation Warning"))
+  def deprecationWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
+    reporter.report(msg.deprecationWarning(pos))
 
-  def migrationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new MigrationWarning(msg, pos, "Migration Warning"))
+  def migrationWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
+    reporter.report(msg.migrationWarning(pos))
 
-  def uncheckedWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new UncheckedWarning(msg, pos, "Unchecked Warning"))
+  def uncheckedWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
+    reporter.report(msg.uncheckedWarning(pos))
 
-  def featureWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new FeatureWarning(msg, pos, "Feature Warning"))
+  def featureWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
+    reporter.report(msg.featureWarning(pos))
 
   def featureWarning(feature: String, featureDescription: String, isScala2Feature: Boolean,
       featureUseSite: Symbol, required: Boolean, pos: SourcePosition): Unit = {
@@ -72,32 +72,24 @@ trait Reporting { this: Context =>
     else reporter.report(new FeatureWarning(msg, pos))
   }
 
-  def warning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new Warning(msg, pos))
-
-  def explainWarning(msg: => MessageCreator, pos: SourcePosition = NoSourcePosition): Unit =
+  def warning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(msg.warning(pos))
 
-  def strictWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
+  def strictWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     if (this.settings.strict.value) error(msg, pos)
-    else warning(msg + "\n(This would be an error under strict mode)", pos)
-
-  def error(msg: => String, pos: SourcePosition = NoSourcePosition): Unit = {
-    // println("*** ERROR: " + msg) // !!! DEBUG
-    reporter.report(new Error(msg, pos))
-  }
+    else warning(msg.mapMsg(_ + "\n(This would be an error under strict mode)"), pos)
 
-  def explainError(msg: => MessageCreator, pos: SourcePosition = NoSourcePosition): Unit =
+  def error(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(msg.error(pos))
 
-  def errorOrMigrationWarning(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
+  def errorOrMigrationWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     if (ctx.scala2Mode) migrationWarning(msg, pos) else error(msg, pos)
 
-  def restrictionError(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    error(s"Implementation restriction: $msg", pos)
+  def restrictionError(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
+    error(msg.mapMsg(m => s"Implementation restriction: $m"), pos)
 
-  def incompleteInputError(msg: String, pos: SourcePosition = NoSourcePosition)(implicit ctx: Context): Unit =
-    reporter.incomplete(new Error(msg, pos))(ctx)
+  def incompleteInputError(msg: Message, pos: SourcePosition = NoSourcePosition)(implicit ctx: Context): Unit =
+    reporter.incomplete(msg.error(pos))(ctx)
 
   /** Log msg if settings.log contains the current phase.
    *  See [[config.CompilerCommand#explainAdvanced]] for the exact meaning of
@@ -184,7 +176,7 @@ trait Reporting { this: Context =>
 abstract class Reporter extends interfaces.ReporterResult {
 
   /** Report a diagnostic */
-  def doReport(d: Message)(implicit ctx: Context): Unit
+  def doReport(d: MessageContainer)(implicit ctx: Context): Unit
 
   /** Whether very long lines can be truncated.  This exists so important
    *  debugging information (like printing the classpath) is not rendered
@@ -199,7 +191,7 @@ abstract class Reporter extends interfaces.ReporterResult {
     finally _truncationOK = saved
   }
 
-  type ErrorHandler = Message => Context => Unit
+  type ErrorHandler = MessageContainer => Context => Unit
   private var incompleteHandler: ErrorHandler = d => c => report(d)(c)
   def withIncompleteHandler[T](handler: ErrorHandler)(op: => T): T = {
     val saved = incompleteHandler
@@ -228,7 +220,7 @@ abstract class Reporter extends interfaces.ReporterResult {
     override def default(key: String) = 0
   }
 
-  def report(d: Message)(implicit ctx: Context): Unit =
+  def report(d: MessageContainer)(implicit ctx: Context): Unit =
     if (!isHidden(d)) {
       doReport(d)(ctx.addMode(Mode.Printing))
       d match {
@@ -242,12 +234,11 @@ abstract class Reporter extends interfaces.ReporterResult {
       }
     }
 
-  def incomplete(d: Message)(implicit ctx: Context): Unit =
+  def incomplete(d: MessageContainer)(implicit ctx: Context): Unit =
     incompleteHandler(d)(ctx)
 
-
   /** Summary of warnings and errors */
-  def summary/*(implicit ctx: Context)*/: String = {
+  def summary: String = {
     val b = new mutable.ListBuffer[String]
     if (warningCount > 0)
       b += countString(warningCount, "warning") + " found"
@@ -275,7 +266,7 @@ abstract class Reporter extends interfaces.ReporterResult {
   }
 
   /** Should this diagnostic not be reported at all? */
-  def isHidden(m: Message)(implicit ctx: Context): Boolean = ctx.mode.is(Mode.Printing)
+  def isHidden(m: MessageContainer)(implicit ctx: Context): Boolean = ctx.mode.is(Mode.Printing)
 
   /** Does this reporter contain not yet reported errors or warnings? */
   def hasPending: Boolean = false
diff --git a/src/dotty/tools/dotc/reporting/StoreReporter.scala b/src/dotty/tools/dotc/reporting/StoreReporter.scala
index fa4fd991fdf9..3744a35dd093 100644
--- a/src/dotty/tools/dotc/reporting/StoreReporter.scala
+++ b/src/dotty/tools/dotc/reporting/StoreReporter.scala
@@ -6,7 +6,7 @@ import core.Contexts.Context
 import collection.mutable
 import Reporter.{Error, Warning}
 import config.Printers.typr
-import diagnostic.Message
+import diagnostic.MessageContainer
 import diagnostic.messages._
 
 /**
@@ -14,9 +14,9 @@ import diagnostic.messages._
  */
 class StoreReporter(outer: Reporter) extends Reporter {
 
-  private var infos: mutable.ListBuffer[Message] = null
+  private var infos: mutable.ListBuffer[MessageContainer] = null
 
-  def doReport(m: Message)(implicit ctx: Context): Unit = {
+  def doReport(m: MessageContainer)(implicit ctx: Context): Unit = {
     typr.println(s">>>> StoredError: ${m.message}") // !!! DEBUG
     if (infos == null) infos = new mutable.ListBuffer
     infos += m
diff --git a/src/dotty/tools/dotc/reporting/ThrowingReporter.scala b/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
index f4e3b472d83b..d8e03ab66ab8 100644
--- a/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ThrowingReporter.scala
@@ -4,7 +4,7 @@ package reporting
 
 import core.Contexts.Context
 import collection.mutable
-import diagnostic.Message
+import diagnostic.MessageContainer
 import diagnostic.messages.Error
 import Reporter._
 
@@ -13,7 +13,7 @@ import Reporter._
  * info to the underlying reporter.
  */
 class ThrowingReporter(reportInfo: Reporter) extends Reporter {
-  def doReport(m: Message)(implicit ctx: Context): Unit = m match {
+  def doReport(m: MessageContainer)(implicit ctx: Context): Unit = m match {
     case _: Error => throw m
     case _ => reportInfo.doReport(m)
   }
diff --git a/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala b/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
index 1ef8b34474a8..c5ff8cb6b593 100644
--- a/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
+++ b/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
@@ -5,7 +5,7 @@ package reporting
 import scala.collection.mutable
 import util.{SourcePosition, SourceFile}
 import core.Contexts.Context
-import diagnostic.Message
+import diagnostic.MessageContainer
 
 /**
  * This trait implements `isHidden` so that multiple messages per position
@@ -18,7 +18,7 @@ trait UniqueMessagePositions extends Reporter {
   /** Logs a position and returns true if it was already logged.
    *  @note  Two positions are considered identical for logging if they have the same point.
    */
-  override def isHidden(m: Message)(implicit ctx: Context): Boolean =
+  override def isHidden(m: MessageContainer)(implicit ctx: Context): Boolean =
     super.isHidden(m) || {
       m.pos.exists && {
         positions get (ctx.source, m.pos.point) match {
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index b3c19820fa08..443dc4de87af 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -3,66 +3,60 @@ package dotc
 package reporting
 package diagnostic
 
-import util.SourcePosition
+import util.{SourcePosition, NoSourcePosition}
 import core.Contexts.Context
 
-import java.util.Optional
-
 object Message {
-  val nonSensicalStartTag = "<nonsensical>"
-  val nonSensicalEndTag = "</nonsensical>"
-
-  implicit class MessageContext(val c: Context) extends AnyVal {
-    def shouldExplain(msg: Message): Boolean = {
-      implicit val ctx: Context = c
-      msg.explanation match {
-        case "" => false
-        case _ => ctx.settings.explain.value
-      }
-    }
-  }
+  implicit def toNoExplanation(str: String): Message =
+    new NoExplanation(str)
 }
 
-class Message(
-  msgFn: => String,
-  val pos: SourcePosition,
-  val level: Int,
-  val kind: String,
-  val explanation: String
-) extends Exception with interfaces.Diagnostic {
-  import Message._
-  private var myMsg: String = null
-  private var myIsNonSensical: Boolean = false
+abstract class Message(val errorId: String) { self =>
+  import messages._
+
+  def msg: String
+  def kind: String
+  def explanation: String
 
-  override def position: Optional[interfaces.SourcePosition] =
-    if (pos.exists && pos.source.exists) Optional.of(pos) else Optional.empty()
+  def container(c: String) =
+    if (kind == "") c
+    else s"$kind $c"
 
-  /** The message to report */
-  def message: String = {
-    if (myMsg == null) {
-      myMsg = msgFn
-      if (myMsg.contains(nonSensicalStartTag)) {
-        myIsNonSensical = true
-        // myMsg might be composed of several d"..." invocations -> nested
-        // nonsensical tags possible
-        myMsg =
-          myMsg
-          .replaceAllLiterally(nonSensicalStartTag, "")
-          .replaceAllLiterally(nonSensicalEndTag, "")
-      }
-    }
-    myMsg
+  def mapMsg(f: String => String) = new Message(errorId) {
+    val msg = f(self.msg)
+    val kind = self.kind
+    val explanation = self.explanation
   }
 
-  /** A message is non-sensical if it contains references to <nonsensical>
-   *  tags.  Such tags are inserted by the error diagnostic framework if a
-   *  message contains references to internally generated error types. Normally
-   *  we want to suppress error messages referring to types like this because
-   *  they look weird and are normally follow-up errors to something that was
-   *  diagnosed before.
-   */
-  def isNonSensical = { message; myIsNonSensical }
+  def error(pos: SourcePosition) =
+    new Error(self, pos, container("Error"), explanation)
+
+  def warning(pos: SourcePosition) =
+    new Warning(self, pos, container("Warning"), explanation)
+
+  def info(pos: SourcePosition) =
+    new Info(self, pos, container("Info"), explanation)
+
+  def featureWarning(pos: SourcePosition) =
+    new FeatureWarning(self, pos, container("Feature Warning"), explanation)
+
+  def uncheckedWarning(pos: SourcePosition) =
+    new UncheckedWarning(self, pos, container("Unchecked Warning"), explanation)
+
+  def deprecationWarning(pos: SourcePosition) =
+    new DeprecationWarning(self, pos, container("Deprecation Warning"), explanation)
+
+  def migrationWarning(pos: SourcePosition) =
+    new MigrationWarning(self, pos, container("Migration Warning"), explanation)
+}
+
+class NoExplanation(val msg: String) extends Message("") {
+  val explanation = ""
+  val kind = ""
+}
 
-  override def toString = s"$getClass at $pos: $message"
-  override def getMessage() = message
+object NoExplanation {
+  def unapply(m: Message): Option[Message] =
+    if (m.explanation == "") Some(m)
+    else None
 }
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
new file mode 100644
index 000000000000..d15c1d2f1f8e
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
@@ -0,0 +1,76 @@
+package dotty.tools
+package dotc
+package reporting
+package diagnostic
+
+import util.SourcePosition
+import core.Contexts.Context
+
+import java.util.Optional
+
+object MessageContainer {
+  val nonSensicalStartTag = "<nonsensical>"
+  val nonSensicalEndTag = "</nonsensical>"
+
+  implicit class MessageContext(val c: Context) extends AnyVal {
+    def shouldExplain(cont: MessageContainer): Boolean = {
+      implicit val ctx: Context = c
+      cont.explanation match {
+        case "" => false
+        case _ => ctx.settings.explain.value
+      }
+    }
+  }
+}
+
+class MessageContainer(
+  msgFn: => Message,
+  val pos: SourcePosition,
+  val level: Int,
+  val kind: String,
+  val explanation: String
+) extends Exception with interfaces.Diagnostic {
+  import MessageContainer._
+  private var myMsg: String = null
+  private var myIsNonSensical: Boolean = false
+  private var myContained: Message = null
+
+  override def position: Optional[interfaces.SourcePosition] =
+    if (pos.exists && pos.source.exists) Optional.of(pos) else Optional.empty()
+
+  /** The message to report */
+  def message: String = {
+    if (myMsg == null) {
+      myMsg = msgFn.msg
+      if (myMsg.contains(nonSensicalStartTag)) {
+        myIsNonSensical = true
+        // myMsg might be composed of several d"..." invocations -> nested
+        // nonsensical tags possible
+        myMsg =
+          myMsg
+          .replaceAllLiterally(nonSensicalStartTag, "")
+          .replaceAllLiterally(nonSensicalEndTag, "")
+      }
+    }
+    myMsg
+  }
+
+  def contained: Message = {
+    if (myContained == null)
+      myContained = msgFn
+
+    myContained
+  }
+
+  /** A message is non-sensical if it contains references to <nonsensical>
+   *  tags.  Such tags are inserted by the error diagnostic framework if a
+   *  message contains references to internally generated error types. Normally
+   *  we want to suppress error messages referring to types like this because
+   *  they look weird and are normally follow-up errors to something that was
+   *  diagnosed before.
+   */
+  def isNonSensical = { message; myIsNonSensical }
+
+  override def toString = s"$getClass at $pos: ${message}"
+  override def getMessage() = message
+}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
deleted file mode 100644
index 99ccca4cc7b6..000000000000
--- a/src/dotty/tools/dotc/reporting/diagnostic/MessageCreator.scala
+++ /dev/null
@@ -1,52 +0,0 @@
-package dotty.tools
-package dotc
-package reporting
-package diagnostic
-
-import util.{SourcePosition, NoSourcePosition}
-import core.Contexts.Context
-
-object MessageCreator {
-  implicit def toNoExplanation(str: String): MessageCreator =
-    new NoExplanation(str)
-}
-
-trait MessageCreator {
-  import messages._
-
-  def msg: String
-  def kind: String
-  def explanation: String
-
-  def error(pos: SourcePosition) =
-    new Error(msg, pos, kind, explanation)
-
-  def warning(pos: SourcePosition) =
-    new Warning(msg, pos, kind, explanation)
-
-  def info(pos: SourcePosition) =
-    new Info(msg, pos, kind, explanation)
-
-  def featureWarnign(pos: SourcePosition) =
-    new FeatureWarning(msg, pos, kind, explanation)
-
-  def uncheckedWarning(pos: SourcePosition) =
-    new UncheckedWarning(msg, pos, kind, explanation)
-
-  def deprecationWarning(pos: SourcePosition) =
-    new DeprecationWarning(msg, pos, kind, explanation)
-
-  def migrationWarning(pos: SourcePosition) =
-    new MigrationWarning(msg, pos, kind, explanation)
-}
-
-class NoExplanation(val msg: String) extends MessageCreator {
-  val explanation = ""
-  val kind = ""
-}
-
-object NoExplanation {
-  def unapply(m: MessageCreator): Option[MessageCreator] =
-    if (m.explanation == "") Some(m)
-    else None
-}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 382e9a29502c..4b7502287436 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -3,37 +3,40 @@ package dotc
 package reporting
 package diagnostic
 
-import dotc.core.Contexts.Context
+import dotc.core._
+import Contexts.Context, Decorators._, Symbols._, Names._
 import util.{SourceFile, NoSource}
 import util.{SourcePosition, NoSourcePosition}
 import config.Settings.Setting
 import interfaces.Diagnostic.{ERROR, WARNING, INFO}
+import dotc.printing.SyntaxHighlighting._
 
 object messages {
 
+  /** Concrete messages to be consumed by the reporter ---------------------- */
   class Error(
-    msgFn: => String,
+    msgFn: => Message,
     pos: SourcePosition,
-    kind: String = "Error",
+    kind: String,
     explanation: String = ""
-  ) extends Message(msgFn, pos, ERROR, kind, explanation)
+  ) extends MessageContainer(msgFn, pos, ERROR, kind, explanation)
 
   class Warning(
-    msgFn: => String,
+    msgFn: => Message,
     pos: SourcePosition,
-    kind: String = "Warning",
+    kind: String,
     explanation: String = ""
-  ) extends Message(msgFn, pos, WARNING, kind, explanation)
+  ) extends MessageContainer(msgFn, pos, WARNING, kind, explanation)
 
   class Info(
-    msgFn: => String,
+    msgFn: => Message,
     pos: SourcePosition,
-    kind: String = "Info",
+    kind: String,
     explanation: String = ""
-  ) extends Message(msgFn, pos, INFO, kind, explanation)
+  ) extends MessageContainer(msgFn, pos, INFO, kind, explanation)
 
   abstract class ConditionalWarning(
-    msgFn: => String,
+    msgFn: => Message,
     pos: SourcePosition,
     kind: String,
     explanation: String = ""
@@ -42,7 +45,7 @@ object messages {
   }
 
   class FeatureWarning(
-    msgFn: => String,
+    msgFn: => Message,
     pos: SourcePosition,
     kind: String = "Feature Warning",
     explanation: String = ""
@@ -51,7 +54,7 @@ object messages {
   }
 
   class UncheckedWarning(
-    msgFn: => String,
+    msgFn: => Message,
     pos: SourcePosition,
     kind: String = "Unchecked Warning",
     explanation: String = ""
@@ -60,7 +63,7 @@ object messages {
   }
 
   class DeprecationWarning(
-    msgFn: => String,
+    msgFn: => Message,
     pos: SourcePosition,
     kind: String = "Deprecation Warning",
     explanation: String = ""
@@ -69,7 +72,7 @@ object messages {
   }
 
   class MigrationWarning(
-    msgFn: => String,
+    msgFn: => Message,
     pos: SourcePosition,
     kind: String = "Migration Warning",
     explanation: String = ""
@@ -77,4 +80,105 @@ object messages {
     def enablingOption(implicit ctx: Context) = ctx.settings.migration
   }
 
+  /**  Messages ----------------------------------------------------------------
+    *
+    *  The role of messages is to provide the necessary details for a simple to
+    *  understand diagnostic event. Each message can be turned into a message
+    *  container (one of the above) by calling the appropriate method on them.
+    *  For instance:
+    *
+    *  ```scala
+    *  EmptyCatchBlock(tree).error   // res: Error
+    *  EmptyCatchBlock(tree).warning // res: Warning
+    *  ```
+    */
+  import dotc.ast.Trees._
+  import dotc.ast.untpd
+
+  /** Syntax Errors --------------------------------------------------------- */
+  abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree, errNo: String)(implicit ctx: Context)
+  extends Message(errNo) {
+     val explanation = {
+       val tryString = tryBody match {
+         case Block(Nil, untpd.EmptyTree) => "{}"
+         case _ => tryBody.show
+       }
+
+       val code1 =
+         s"""|try $tryString catch {
+             |  case t: Throwable => ???
+             |}""".stripMargin
+
+       val code2 =
+         s"""|try $tryString finally {
+             |  // perform your cleanup here!
+             |}""".stripMargin
+
+       hl"""|A ${"try"} expression should be followed by some mechanism to handle any exceptions
+            |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
+            |on any expected exceptions. For example:
+            |
+            |$code1
+            |
+            |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
+            |exception propagate - but still allowing for some clean up in ${"finally"}:
+            |
+            |$code2""".stripMargin
+     }
+   }
+
+   class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
+   extends EmptyCatchOrFinallyBlock(tryBody, "E001") {
+     val kind = "Syntax"
+     val msg =
+       hl"""|The ${"catch"} block does not contain a valid expression, try
+            |adding a case like - `${"case e: Exception =>"}` to the block""".stripMargin
+   }
+
+   case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context)
+   extends EmptyCatchOrFinallyBlock(tryBody, "E002") {
+     val kind = "Syntax"
+     val msg =
+       hl"""|A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting
+            |its body in a block; no exceptions are handled.""".stripMargin
+   }
+
+  /** Type Errors ----------------------------------------------------------- */
+  class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context)
+  extends Message("E003") {
+    val kind = "Naming"
+    val msg = em"duplicate pattern variable: `${bind.name}`"
+
+    val explanation = {
+      val pat = tree.pat.show
+      val guard = tree.guard match {
+        case untpd.EmptyTree => ""
+        case guard => s"if ${guard.show}"
+      }
+
+      val body = tree.body match {
+        case Block(Nil, untpd.EmptyTree) => ""
+        case body => s" ${body.show}"
+      }
+
+      val caseDef = s"case $pat$guard => $body"
+
+      hl"""|For each ${"case"} bound variable names  have to be unique. In:
+           |
+           |$caseDef
+           |
+           |`${bind.name}` is not unique. Rename one of the bound variables!""".stripMargin
+    }
+  }
+
+  class MissingIdent(tree: untpd.Ident, treeKind: String, name: Name)(implicit ctx: Context)
+  extends Message("E004") {
+    val kind = "Missing identifier"
+    val msg = em"not found: $treeKind$name"
+
+    val explanation = {
+      hl"""|An identifier for `${name.show}` is missing. This means that something
+           |has either been misspelt or you're forgetting an import""".stripMargin
+    }
+  }
 }
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/parser.scala b/src/dotty/tools/dotc/reporting/diagnostic/parser.scala
deleted file mode 100644
index b73e353eba79..000000000000
--- a/src/dotty/tools/dotc/reporting/diagnostic/parser.scala
+++ /dev/null
@@ -1,8 +0,0 @@
-package dotty.tools
-package dotc
-package reporting
-package diagnostic
-
-object parser {
-
-}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala b/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
deleted file mode 100644
index b9a662c7ddf5..000000000000
--- a/src/dotty/tools/dotc/reporting/diagnostic/syntax.scala
+++ /dev/null
@@ -1,61 +0,0 @@
-package dotty.tools
-package dotc
-package reporting
-package diagnostic
-
-import dotc.core._
-import Contexts.Context, Decorators._, Symbols._
-import dotc.printing.SyntaxHighlighting._
-import util.{SourcePosition, NoSourcePosition}
-
-object syntax {
-  import dotc.ast.Trees._
-  import dotc.ast.untpd
-
-  abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context) extends MessageCreator {
-    val explanation = {
-      val tryString = tryBody match {
-        case Block(Nil, untpd.EmptyTree) => "{}"
-        case _ => tryBody.show
-      }
-
-      val code1 =
-        s"""|try $tryString catch {
-            |  case t: Throwable => ???
-            |}""".stripMargin
-
-      val code2 =
-        s"""|try $tryString finally {
-            |  // perform your cleanup here!
-            |}""".stripMargin
-
-      hl"""|A ${"try"} expression should be followed by some mechanism to handle any exceptions
-           |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
-           |on any expected exceptions. For example:
-           |
-           |$code1
-           |
-           |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
-           |exception propagate - but still allowing for some clean up in ${"finally"}:
-           |
-           |$code2
-           """.stripMargin
-    }
-  }
-
-  class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
-  extends EmptyCatchOrFinallyBlock(tryBody) {
-    val kind = "Syntax"
-    val msg =
-      hl"""|The ${"catch"} block does not contain a valid expression, try
-           |adding a case like - `${"case e: Exception =>"}` to the block""".stripMargin
-  }
-
-  case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context)
-  extends EmptyCatchOrFinallyBlock(tryBody) {
-    val kind = "Syntax"
-    val msg =
-      hl"""|A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting
-           |its body in a block; no exceptions are handled.""".stripMargin
-  }
-}
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala b/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala
deleted file mode 100644
index ee221f80d9c9..000000000000
--- a/src/dotty/tools/dotc/reporting/diagnostic/tpe.scala
+++ /dev/null
@@ -1,55 +0,0 @@
-package dotty.tools
-package dotc
-package reporting
-package diagnostic
-
-import dotc.core._
-import Contexts.Context, Decorators._, Symbols._, Names._
-import dotc.printing.SyntaxHighlighting._
-import util.{SourcePosition, NoSourcePosition}
-
-object tpe {
-  import dotc.ast.Trees._
-  import dotc.ast.untpd
-
-  class DuplicateBind(
-    bind: untpd.Bind,
-    tree: untpd.CaseDef
-  )(implicit ctx: Context) extends MessageCreator {
-    val kind = "Naming"
-
-    val msg =
-      em"duplicate pattern variable: `${bind.name}`"
-
-    val explanation = {
-      val pat = tree.pat.show
-      val guard = tree.guard match {
-        case untpd.EmptyTree => ""
-        case guard => s"if ${guard.show}"
-      }
-
-      val body = tree.body match {
-        case Block(Nil, untpd.EmptyTree) => ""
-        case body => s" ${body.show}"
-      }
-
-      val caseDef = s"case $pat$guard => $body"
-
-      hl"""|For each ${"case"} bound variable names  have to be unique. In:
-           |
-           |$caseDef
-           |
-           |`${bind.name}` is not unique. Rename one of the bound variables!""".stripMargin
-    }
-  }
-
-  class MissingIdent(tree: untpd.Ident, treeKind: String, name: Name)(implicit ctx: Context) extends MessageCreator {
-    val kind = "Missing identifier"
-    val msg = em"not found: $treeKind$name"
-
-    val explanation = {
-      hl"""|An identifier for `${name.show}` is missing. This means that something
-           |has either been misspelt or you're forgetting an import""".stripMargin
-    }
-  }
-}
diff --git a/src/dotty/tools/dotc/typer/ErrorReporting.scala b/src/dotty/tools/dotc/typer/ErrorReporting.scala
index 43c09351050b..8b740c3dc656 100644
--- a/src/dotty/tools/dotc/typer/ErrorReporting.scala
+++ b/src/dotty/tools/dotc/typer/ErrorReporting.scala
@@ -11,6 +11,7 @@ import util.Positions._
 import printing.{Showable, RefinedPrinter}
 import scala.collection.mutable
 import java.util.regex.Matcher.quoteReplacement
+import reporting.diagnostic.Message
 
 object ErrorReporting {
 
@@ -19,7 +20,7 @@ object ErrorReporting {
   def errorTree(tree: untpd.Tree, msg: => String)(implicit ctx: Context): tpd.Tree =
     tree withType errorType(msg, tree.pos)
 
-  def errorType(msg: => String, pos: Position)(implicit ctx: Context): ErrorType = {
+  def errorType(msg: => Message, pos: Position)(implicit ctx: Context): ErrorType = {
     ctx.error(msg, pos)
     ErrorType
   }
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index b29254b8924f..0cc04613ad7a 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -65,8 +65,8 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
   import tpd.{cpy => _, _}
   import untpd.cpy
   import Dynamic.isDynamicMethod
-  import reporting.diagnostic.MessageCreator
-  import reporting.diagnostic.tpe._
+  import reporting.diagnostic.Message
+  import reporting.diagnostic.messages._
 
   /** A temporary data item valid for a single typed ident:
    *  The set of all root import symbols that have been
@@ -99,7 +99,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
     /** Method is necessary because error messages need to bind to
      *  to typedIdent's context which is lost in nested calls to findRef
      */
-    def error(msg: => MessageCreator, pos: Position) = ctx.explainError(msg, pos)
+    def error(msg: => Message, pos: Position) = ctx.error(msg, pos)
 
     /** Is this import a root import that has been shadowed by an explicit
      *  import in the same program?
@@ -772,10 +772,10 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
                 TypeTree(pt)
               case _ =>
                 if (!mt.isDependent) EmptyTree
-                else throw new Error(i"internal error: cannot turn dependent method type $mt into closure, position = ${tree.pos}, raw type = ${mt.toString}") // !!! DEBUG. Eventually, convert to an error?
+                else throw new java.lang.Error(i"internal error: cannot turn dependent method type $mt into closure, position = ${tree.pos}, raw type = ${mt.toString}") // !!! DEBUG. Eventually, convert to an error?
             }
           case tp =>
-            throw new Error(i"internal error: closing over non-method $tp, pos = ${tree.pos}")
+            throw new java.lang.Error(i"internal error: closing over non-method $tp, pos = ${tree.pos}")
         }
       else typed(tree.tpt)
     //println(i"typing closure $tree : ${meth1.tpe.widen}")
@@ -848,7 +848,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         super.transform(trt.withType(elimWildcardSym(trt.tpe))) match {
           case b: Bind =>
             if (ctx.scope.lookup(b.name) == NoSymbol) ctx.enter(b.symbol)
-            else ctx.explainError(new DuplicateBind(b, tree), b.pos)
+            else ctx.error(new DuplicateBind(b, tree), b.pos)
             b.symbol.info = elimWildcardSym(b.symbol.info)
             b
           case t => t
diff --git a/test/test/CompilerTest.scala b/test/test/CompilerTest.scala
index 942948f085a1..8cf6b2feb1d2 100644
--- a/test/test/CompilerTest.scala
+++ b/test/test/CompilerTest.scala
@@ -5,7 +5,7 @@ import dotty.partest.DPConfig
 import dotty.tools.dotc.{Main, Bench, Driver}
 import dotty.tools.dotc.interfaces.Diagnostic.ERROR
 import dotty.tools.dotc.reporting._
-import diagnostic.Message
+import diagnostic.MessageContainer
 import dotty.tools.dotc.util.SourcePosition
 import dotty.tools.dotc.config.CompilerCommand
 import dotty.tools.io.PlainFile
@@ -238,7 +238,7 @@ abstract class CompilerTest {
     val storeReporter = new Reporter with UniqueMessagePositions with HideNonSensicalMessages {
       private val consoleReporter = new ConsoleReporter()
       private val innerStoreReporter = new StoreReporter(consoleReporter)
-      def doReport(m: Message)(implicit ctx: Context): Unit = {
+      def doReport(m: MessageContainer)(implicit ctx: Context): Unit = {
         if (m.level == ERROR) {
           innerStoreReporter.flush()
           consoleReporter.doReport(m)
diff --git a/test/test/OtherEntryPointsTest.scala b/test/test/OtherEntryPointsTest.scala
index 824034055632..abaa043c0111 100644
--- a/test/test/OtherEntryPointsTest.scala
+++ b/test/test/OtherEntryPointsTest.scala
@@ -5,7 +5,7 @@ import org.junit.Assert._
 import dotty.tools.dotc.Main
 import dotty.tools.dotc.interfaces.{CompilerCallback, SourceFile}
 import dotty.tools.dotc.reporting._
-import dotty.tools.dotc.reporting.diagnostic.Message
+import dotty.tools.dotc.reporting.diagnostic.MessageContainer
 import dotty.tools.dotc.core.Contexts._
 import java.io.File
 import scala.collection.mutable.ListBuffer
@@ -51,7 +51,7 @@ class OtherEntryPointsTest {
   private class CustomReporter extends Reporter
       with UniqueMessagePositions
       with HideNonSensicalMessages {
-    def doReport(m: Message)(implicit ctx: Context): Unit = {
+    def doReport(m: MessageContainer)(implicit ctx: Context): Unit = {
     }
   }
 

From 1532c82788ab2366df04cac2e418d3db98390ef4 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 19 Sep 2016 20:00:44 +0200
Subject: [PATCH 23/53] Remove duplication of console reporters

---
 src/dotty/tools/dotc/Compiler.scala           |  2 +-
 src/dotty/tools/dotc/core/Contexts.scala      |  2 +-
 .../dotc/repl/CompilingInterpreter.scala      | 40 +++-----
 .../dotc/reporting/ConsoleReporter.scala      | 86 +++++++++++-----
 .../dotc/reporting/FancyConsoleReporter.scala | 93 ------------------
 test/test/TestREPL.scala                      |  4 +-
 tests/repl/errmsgs.check                      | 97 ++++++++++---------
 tests/repl/imports.check                      | 22 +++--
 8 files changed, 148 insertions(+), 198 deletions(-)
 delete mode 100644 src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala

diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index ea6254f5b802..178cba7c4080 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -8,7 +8,7 @@ import Symbols._
 import Types._
 import Scopes._
 import typer.{FrontEnd, Typer, ImportInfo, RefChecks}
-import reporting.{Reporter, ConsoleReporter, FancyConsoleReporter}
+import reporting.{Reporter, ConsoleReporter}
 import Phases.Phase
 import transform._
 import transform.TreeTransforms.{TreeTransform, TreeTransformer}
diff --git a/src/dotty/tools/dotc/core/Contexts.scala b/src/dotty/tools/dotc/core/Contexts.scala
index d1447a98f168..5c9fdaf886ee 100644
--- a/src/dotty/tools/dotc/core/Contexts.scala
+++ b/src/dotty/tools/dotc/core/Contexts.scala
@@ -501,7 +501,7 @@ object Contexts {
     outer = NoContext
     period = InitialPeriod
     mode = Mode.None
-    typerState = new TyperState(new FancyConsoleReporter())
+    typerState = new TyperState(new ConsoleReporter())
     printerFn = new RefinedPrinter(_)
     owner = NoSymbol
     sstate = settings.defaultState
diff --git a/src/dotty/tools/dotc/repl/CompilingInterpreter.scala b/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
index 70b32a16ae33..0964de303094 100644
--- a/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
+++ b/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
@@ -16,7 +16,7 @@ import scala.collection.mutable.{ListBuffer, HashSet, ArrayBuffer}
 //import ast.parser.SyntaxAnalyzer
 import io.{PlainFile, VirtualDirectory}
 import scala.reflect.io.{PlainDirectory, Directory}
-import reporting.{ConsoleReporter, FancyConsoleReporter, Reporter}
+import reporting.{ConsoleReporter, Reporter}
 import core.Flags
 import util.{SourceFile, NameTransformer}
 import io.ClassPath
@@ -117,30 +117,22 @@ class CompilingInterpreter(
     }
   }
 
-  private def customPrintMessage(msg: String) = {
-    if (!delayOutput) {
-      out.print(/*clean*/(msg) + "\n")
-        // Suppress clean for now for compiler messages
-        // Otherwise we will completely delete all references to
-        // line$object$ module classes. The previous interpreter did not
-        // have the project because the module class was written without the final `$'
-        // and therefore escaped the purge. We can turn this back on once
-        // we drop the final `$' from module classes.
-      out.flush()
-    } else {
-      previousOutput += (/*clean*/(msg) + "\n")
+  private def newReporter =
+    new ConsoleReporter(Console.in, out) {
+      override def printMessage(msg: String) =
+        if (!delayOutput) {
+          out.print(/*clean*/(msg) + "\n")
+          // Suppress clean for now for compiler messages
+          // Otherwise we will completely delete all references to
+          // line$object$ module classes. The previous interpreter did not
+          // have the project because the module class was written without the final `$'
+          // and therefore escaped the purge. We can turn this back on once
+          // we drop the final `$' from module classes.
+          out.flush()
+        } else {
+          previousOutput += (/*clean*/(msg) + "\n")
+        }
     }
-  }
-
-  private def newReporter(implicit ctx: Context) =
-    if (ctx.settings.color.value == "never")
-      new ConsoleReporter(Console.in, out) {
-        override def printMessage(msg: String) = customPrintMessage(msg)
-      }
-    else
-      new FancyConsoleReporter(Console.in, out) {
-        override def printMessage(msg: String) = customPrintMessage(msg)
-      }
 
   /** the previous requests this interpreter has processed */
   private val prevRequests = new ArrayBuffer[Request]()
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 92eea9fa9de3..a5979bd5bcc6 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -8,13 +8,14 @@ import core.Contexts._
 import Reporter._
 import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
-import diagnostic.Message
-import diagnostic.MessageContainer
+import printing.SyntaxHighlighting._
+import printing.Highlighting._
+import diagnostic.{ Message, MessageContainer }
 import diagnostic.messages._
 
 /**
- * This class implements a Reporter that displays messages on a text
- * console.
+ * This class implements a more Fancy version (with colors!) of the regular
+ * `ConsoleReporter`
  */
 class ConsoleReporter(
   reader: BufferedReader = Console.in,
@@ -26,32 +27,72 @@ class ConsoleReporter(
   /** maximal number of error messages to be printed */
   protected def ErrorLimit = 100
 
-  def printSourceLine(pos: SourcePosition) =
-    printMessage(pos.lineContent.stripLineEnd)
-
-  def printColumnMarker(pos: SourcePosition) =
-    if (pos.exists) { printMessage(" " * pos.column + "^") }
-
   /** Prints the message. */
   def printMessage(msg: String): Unit = { writer.print(msg + "\n"); writer.flush() }
 
+  def stripColor(str: String): String =
+    str.replaceAll("\u001B\\[[;\\d]*m", "")
+
+  def sourceLine(pos: SourcePosition)(implicit ctx: Context): (String, Int) = {
+    val lineNum = s"${pos.line}:"
+    (lineNum + hl"${pos.lineContent.stripLineEnd}", lineNum.length)
+  }
+
+  def columnMarker(pos: SourcePosition, offset: Int)(implicit ctx: Context) =
+    if (pos.startLine == pos.endLine) {
+      val whitespace = " " * (pos.column + offset)
+      val carets =
+        Red("^" * math.max(1, pos.endColumn - pos.startColumn))
+
+      whitespace + carets.show
+    } else {
+      Red(" " * (pos.column + offset) + "^").show
+    }
+
+  def errorMsg(pos: SourcePosition, msg: String, offset: Int)(implicit ctx: Context) = {
+    var hasLongLines = false
+    val leastWhitespace = msg.lines.foldLeft(Int.MaxValue) { (minPad, line) =>
+      val lineLength = stripColor(line).length
+      val padding =
+        math.min(math.max(0, ctx.settings.pageWidth.value - offset - lineLength), offset + pos.startColumn)
+
+      if (padding < minPad) padding
+      else minPad
+    }
+
+    msg
+      .lines
+      .map { line => " " * leastWhitespace + line }
+      .mkString(sys.props("line.separator"))
+  }
+
+  def posStr(pos: SourcePosition, kind: String, errorId: String)(implicit ctx: Context) =
+    if (pos.exists) Blue({
+      val file = pos.source.file.toString
+      val errId = if (errorId != "") s"[$errorId] " else ""
+      val prefix = s"-- ${errId}${kind}: $file "
+      prefix +
+      ("-" * math.max(ctx.settings.pageWidth.value - stripColor(prefix).length, 0))
+    }).show else ""
+
   /** Prints the message with the given position indication. */
   def printMessageAndPos(msg: Message, pos: SourcePosition, kind: String)(implicit ctx: Context): Unit = {
-    val posStr = if (pos.exists) s"$pos: " else ""
-    printMessage(s"${posStr}${kind}: ${msg.msg}")
+    printMessage(posStr(pos, kind, msg.errorId))
     if (pos.exists) {
-      printSourceLine(pos)
-      printColumnMarker(pos)
-    }
+      val (src, offset) = sourceLine(pos)
+      val marker = columnMarker(pos, offset)
+      val err = errorMsg(pos, msg.msg, offset)
+
+      printMessage(List(src, marker, err).mkString("\n"))
+    } else printMessage(msg.msg)
   }
 
-  def printExplanation(m: Message)(implicit ctx: Context): Unit =
-    printMessage(
-      s"""|
-          |Explanation
-          |===========
-          |${m.explanation}""".stripMargin
-    )
+  def printExplanation(m: Message)(implicit ctx: Context): Unit = {
+    printMessage(hl"""|
+                      |${Blue("Explanation")}
+                      |${Blue("===========")}""".stripMargin)
+    printMessage(m.explanation)
+  }
 
   override def doReport(m: MessageContainer)(implicit ctx: Context): Unit = {
     m match {
@@ -87,3 +128,4 @@ class ConsoleReporter(
 
   override def flush()(implicit ctx: Context): Unit = { writer.flush() }
 }
+
diff --git a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala b/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
deleted file mode 100644
index 725e69ff85d9..000000000000
--- a/src/dotty/tools/dotc/reporting/FancyConsoleReporter.scala
+++ /dev/null
@@ -1,93 +0,0 @@
-package dotty.tools
-package dotc
-package reporting
-
-import scala.collection.mutable
-import util.SourcePosition
-import core.Contexts._
-import Reporter._
-import java.io.{ BufferedReader, IOException, PrintWriter }
-import scala.reflect.internal.util._
-import printing.SyntaxHighlighting._
-import printing.Highlighting._
-import diagnostic.Message
-
-/**
- * This class implements a more Fancy version (with colors!) of the regular
- * `ConsoleReporter`
- */
-class FancyConsoleReporter(
-  reader: BufferedReader = Console.in,
-  writer: PrintWriter = new PrintWriter(Console.err, true)
-) extends ConsoleReporter(reader, writer) {
-
-  def stripColor(str: String): String =
-    str.replaceAll("\u001B\\[[;\\d]*m", "")
-
-  def sourceLine(pos: SourcePosition)(implicit ctx: Context): (String, Int) = {
-    val lineNum = s"${pos.line}:"
-    (lineNum + hl"${pos.lineContent.stripLineEnd}", lineNum.length)
-  }
-
-  def columnMarker(pos: SourcePosition, offset: Int)(implicit ctx: Context) =
-    if (pos.startLine == pos.endLine) {
-      val whitespace = " " * (pos.column + offset)
-      val carets =
-        Red("^" * math.max(1, pos.endColumn - pos.startColumn))
-
-      whitespace + carets.show
-    } else {
-      Red(" " * (pos.column + offset) + "^").show
-    }
-
-  def errorMsg(pos: SourcePosition, msg: String, offset: Int)(implicit ctx: Context) = {
-    var hasLongLines = false
-    val leastWhitespace = msg.lines.foldLeft(Int.MaxValue) { (minPad, line) =>
-      val lineLength = stripColor(line).length
-      val padding =
-        math.min(math.max(0, ctx.settings.pageWidth.value - offset - lineLength), offset + pos.startColumn)
-
-      if (padding < minPad) padding
-      else minPad
-    }
-
-    msg
-      .lines
-      .map { line => " " * leastWhitespace + line }
-      .mkString(sys.props("line.separator"))
-  }
-
-  def posStr(pos: SourcePosition, kind: String)(implicit ctx: Context) =
-    if (pos.exists) Blue({
-      val file = pos.source.file.toString
-
-      val outer = if (pos.outer.exists) {
-        s"This location is in code that was inlined at ${pos.outer}:\n" +
-        printStr(pos.outer) + "\n" + "-" * ctx.settings.pageWidth.value
-      } else ""
-
-      val prefix = s"-- $kind: $file "
-      prefix +
-      ("-" * math.max(ctx.settings.pageWidth.value - stripColor(prefix).length, 0)) +
-      "\n" + outer
-    }).show else ""
-
-  /** Prints the message with the given position indication. */
-  override def printMessageAndPos(msg: Message, pos: SourcePosition, kind: String)(implicit ctx: Context): Unit = {
-    printMessage(posStr(pos, kind))
-    if (pos.exists) {
-      val (src, offset) = sourceLine(pos)
-      val marker = columnMarker(pos, offset)
-      val err = errorMsg(pos, msg.msg, offset)
-
-      printMessage(List(src, marker, err).mkString("\n"))
-    } else printMessage(msg.msg)
-  }
-
-  override def printExplanation(m: Message)(implicit ctx: Context): Unit = {
-    printMessage(hl"""|
-                      |${Blue("Explanation")}
-                      |${Blue("===========")}""".stripMargin)
-    printMessage(m.explanation)
-  }
-}
diff --git a/test/test/TestREPL.scala b/test/test/TestREPL.scala
index 9867cb4ecf20..090c774bb7d6 100644
--- a/test/test/TestREPL.scala
+++ b/test/test/TestREPL.scala
@@ -21,7 +21,9 @@ class TestREPL(script: String) extends REPL {
     override val output = new NewLinePrintWriter(out)
 
     override def context(ctx: Context) =
-      ctx.fresh.setSetting(ctx.settings.color, "never")
+      ctx.fresh
+        .setSetting(ctx.settings.color, "never")
+        .setSetting(ctx.settings.pageWidth, 80)
 
     override def input(in: Interpreter)(implicit ctx: Context) = new InteractiveReader {
       val lines = script.lines.buffered
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index e32e72d1f7b0..d8c1b9215e74 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -1,43 +1,48 @@
 scala> class Inv[T](x: T)
 defined class Inv
 scala> val x: List[String] = List(1)
-<console>:4: Error: type mismatch:
-found:    Int(1)
-required: String
-val x: List[String] = List(1)
-                           ^
+-- Error: <console> ------------------------------------------------------------
+3:val x: List[String] = List(1)
+                             ^
+                             type mismatch:
+                             found:    Int(1)
+                             required: String
 scala> val y: List[List[String]] = List(List(1))
-<console>:4: Error: type mismatch:
-found:    Int(1)
-required: String
-val y: List[List[String]] = List(List(1))
-                                      ^
+-- Error: <console> ------------------------------------------------------------
+3:val y: List[List[String]] = List(List(1))
+                                        ^
+                                        type mismatch:
+                                        found:    Int(1)
+                                        required: String
 scala> val z: (List[String], List[Int]) = (List(1), List("a"))
-<console>:4: Error: type mismatch:
-found:    Int(1)
-required: String
-val z: (List[String], List[Int]) = (List(1), List("a"))
-                                         ^
-<console>:4: Error: type mismatch:
-found:    String("a")
-required: Int
-val z: (List[String], List[Int]) = (List(1), List("a"))
-                                                  ^
+-- Error: <console> ------------------------------------------------------------
+3:val z: (List[String], List[Int]) = (List(1), List("a"))
+                                           ^
+                                           type mismatch:
+                                           found:    Int(1)
+                                           required: String
+-- Error: <console> ------------------------------------------------------------
+3:val z: (List[String], List[Int]) = (List(1), List("a"))
+                                                    ^
+                                                    type mismatch:
+                                                    found:    String("a")
+                                                    required: Int
 scala> val a: Inv[String] = new Inv(new Inv(1))
-<console>:5: Error: type mismatch:
-found:    Inv[T]
-required: String
-
-where  T  is a type variable with constraint >: Int(1)
-
-val a: Inv[String] = new Inv(new Inv(1))
-                                 ^
+-- Error: <console> ------------------------------------------------------------
+4:val a: Inv[String] = new Inv(new Inv(1))
+                                   ^^^^
+                        type mismatch:
+                        found:    Inv[T]
+                        required: String
+                        
+                        where  T  is a type variable with constraint >: Int(1)
 scala> val b: Inv[String] = new Inv(1)
-<console>:5: Error: type mismatch:
-found:    Int(1)
-required: String
-val b: Inv[String] = new Inv(1)
-                             ^
+-- Error: <console> ------------------------------------------------------------
+4:val b: Inv[String] = new Inv(1)
+                               ^
+                               type mismatch:
+                               found:    Int(1)
+                               required: String
 scala> abstract class C {
            type T
            val x: T
@@ -53,22 +58,22 @@ scala> abstract class C {
              }
            }
          }
-<console>:9: Error: type mismatch:
-found:    C.this.T(C.this.x)
-required: T'
-
-where  T   is a type in class C
-       T'  is a type in the initalizer of value s which is an alias of String
-
-      var y: T = x
-                 ^
-<console>:13: Error: type mismatch:
+-- Error: <console> ------------------------------------------------------------
+8:      var y: T = x
+                   ^
+ type mismatch:
+ found:    C.this.T(C.this.x)
+ required: T'
+ 
+ where  T   is a type in class C
+        T'  is a type in the initalizer of value s which is an alias of String
+-- Error: <console> ------------------------------------------------------------
+12:          val z: T = y
+                        ^
+type mismatch:
 found:    T(y)
 required: T'
 
 where  T   is a type in the initalizer of value s which is an alias of String
        T'  is a type in method f which is an alias of Int
-
-          val z: T = y
-                     ^
 scala> :quit
diff --git a/tests/repl/imports.check b/tests/repl/imports.check
index 50b7a93d7f03..f9e48c0119a1 100644
--- a/tests/repl/imports.check
+++ b/tests/repl/imports.check
@@ -7,16 +7,18 @@ defined module o
 scala> import o._
 import o._
 scala> buf += xs
-<console>:11: Error: type mismatch:
-found:    scala.collection.immutable.List[Int](o.xs)
-required: String
-buf += xs
-       ^
-<console>:11: Error: type mismatch:
-found:    String
-required: scala.collection.mutable.ListBuffer[Int]
-buf += xs
-^
+-- Error: <console> ------------------------------------------------------------
+10:buf += xs
+          ^^
+          type mismatch:
+          found:    scala.collection.immutable.List[Int](o.xs)
+          required: String
+-- Error: <console> ------------------------------------------------------------
+10:buf += xs
+   ^^^^^^^^^
+   type mismatch:
+   found:    String
+   required: scala.collection.mutable.ListBuffer[Int]
 scala> buf ++= xs
 res1: scala.collection.mutable.ListBuffer[Int] = ListBuffer(1, 2, 3)
 scala> :quit

From 146add1421f4a92396fc2461ff362fee4527d7f8 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 19 Sep 2016 23:03:03 +0200
Subject: [PATCH 24/53] Improve syntax highlighting for ValDefs

---
 .../dotc/printing/SyntaxHighlighting.scala    | 54 +++++++++++++------
 1 file changed, 37 insertions(+), 17 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 95e59ccf347e..863b089610cb 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -26,17 +26,20 @@ object SyntaxHighlighting {
   }
 
   val NoColor         = Console.RESET
-  val CommentColor    = Console.GREEN
-  val KeywordColor    = Console.CYAN
-  val LiteralColor    = Console.MAGENTA
-  val TypeColor       = Console.GREEN
-  val AnnotationColor = Console.RED
+  val CommentColor    = Console.BLUE
+  val KeywordColor    = Console.YELLOW
+  val ValDefColor     = Console.CYAN
+  val LiteralColor    = Console.RED
+  val TypeColor       = Console.MAGENTA
+  val AnnotationColor = Console.MAGENTA
 
-  private def none(str: String)       = str
-  private def keyword(str: String)    = KeywordColor + str + NoColor
-  private def typeDef(str: String)    = TypeColor + str + NoColor
-  private def literal(str: String)    = LiteralColor + str + NoColor
-  private def annotation(str: String) = AnnotationColor + str + NoColor
+  private def none(str: String) = str
+  private def keyword(str: String) = KeywordColor + str + NoColor
+  private def typeDef(str: String) = TypeColor + str + NoColor
+  private def literal(str: String) = LiteralColor + str + NoColor
+  private def valDef(str: String) = ValDefColor + str + NoColor
+  private def annotation(str: String) =
+    if (str.trim == "@") str else AnnotationColor + str + NoColor
   private val tripleQs = Console.RED_B + "???" + NoColor
 
   private val keywords: Seq[String] = for {
@@ -57,6 +60,7 @@ object SyntaxHighlighting {
     var prev: Char = 0
     var remaining  = chars.toStream
     val newBuf     = new StringBuilder
+    var lastToken  = ""
 
     @inline def keywordStart =
       prev == 0 || prev == ' ' || prev == '{' || prev == '(' || prev == '\n'
@@ -117,7 +121,7 @@ object SyntaxHighlighting {
             else newBuf += n
             prev = '#'
           case '@'  =>
-            appendWhile('@', _ != ' ', annotation)
+            appendWhile('@', !typeEnders.contains(_), annotation)
           case '\"' =>
             appendLiteral('\"', multiline = remaining.take(2).mkString == "\"\"")
           case '\'' =>
@@ -191,7 +195,7 @@ object SyntaxHighlighting {
           prev = '$'
         } else if (next == '{') {
           var open = 1 // keep track of open blocks
-          newBuf append (KeywordColor + curr)
+          newBuf append (ValDefColor + curr)
           newBuf += next
           while (remaining.nonEmpty && open > 0) {
             var c = takeChar()
@@ -201,7 +205,7 @@ object SyntaxHighlighting {
           }
           newBuf append LiteralColor
         } else {
-          newBuf append (KeywordColor + curr)
+          newBuf append (ValDefColor + curr)
           newBuf += next
           var c: Char = 'a'
           while (c.isLetterOrDigit && remaining.nonEmpty) {
@@ -249,15 +253,31 @@ object SyntaxHighlighting {
     def append(c: Char, shouldHL: String => Boolean, highlight: String => String) = {
       var curr: Char = 0
       val sb = new StringBuilder(s"$c")
-      while (remaining.nonEmpty && curr != ' ' && curr != '(' && curr != '\n') {
+
+      def delim(c: Char) = (c: @switch) match {
+        case ' ' => true
+        case '\n' => true
+        case '(' => true
+        case ':' => true
+        case '@' => true
+        case _ => false
+      }
+
+      while (remaining.nonEmpty && !delim(curr)) {
         curr = takeChar()
-        if (curr != ' ' && curr != '\n') sb += curr
+        if (!delim(curr)) sb += curr
       }
 
       val str    = sb.toString
-      val toAdd  = if (shouldHL(str)) highlight(str) else str
-      val suffix = if (curr == ' ' || curr == '\n') s"$curr" else ""
+      val toAdd  =
+        if (shouldHL(str))
+          highlight(str)
+        else if (lastToken == "val" || lastToken == "def" || lastToken == "case")
+          valDef(str)
+        else str
+      val suffix = if (delim(curr)) s"$curr" else ""
       newBuf append (toAdd + suffix)
+      lastToken = str
       prev = curr
     }
 

From bf8803d6d5b49e20e043564129c2109892842fa7 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 19 Sep 2016 23:07:06 +0200
Subject: [PATCH 25/53] Add deprecation message on `with` type operator

---
 src/dotty/tools/dotc/parsing/Parsers.scala    |   2 +-
 .../dotc/reporting/diagnostic/messages.scala  | 124 +++++++++++-------
 2 files changed, 78 insertions(+), 48 deletions(-)

diff --git a/src/dotty/tools/dotc/parsing/Parsers.scala b/src/dotty/tools/dotc/parsing/Parsers.scala
index dcd59629832c..620cc1273272 100644
--- a/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -734,7 +734,7 @@ object Parsers {
 
     def withTypeRest(t: Tree): Tree =
       if (in.token == WITH) {
-        deprecationWarning("`with' as a type operator has been deprecated; use `&' instead")
+        deprecationWarning(DeprecatedWithOperator())
         in.nextToken()
         AndTypeTree(t, withType())
       }
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 4b7502287436..cf67e8989549 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -13,7 +13,7 @@ import dotc.printing.SyntaxHighlighting._
 
 object messages {
 
-  /** Concrete messages to be consumed by the reporter ---------------------- */
+  /** Message container to be consumed by the reporter ---------------------- */
   class Error(
     msgFn: => Message,
     pos: SourcePosition,
@@ -98,54 +98,84 @@ object messages {
   /** Syntax Errors --------------------------------------------------------- */
   abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree, errNo: String)(implicit ctx: Context)
   extends Message(errNo) {
-     val explanation = {
-       val tryString = tryBody match {
-         case Block(Nil, untpd.EmptyTree) => "{}"
-         case _ => tryBody.show
-       }
-
-       val code1 =
-         s"""|try $tryString catch {
-             |  case t: Throwable => ???
-             |}""".stripMargin
-
-       val code2 =
-         s"""|try $tryString finally {
-             |  // perform your cleanup here!
-             |}""".stripMargin
-
-       hl"""|A ${"try"} expression should be followed by some mechanism to handle any exceptions
-            |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
-            |on any expected exceptions. For example:
-            |
-            |$code1
-            |
-            |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
-            |exception propagate - but still allowing for some clean up in ${"finally"}:
-            |
-            |$code2""".stripMargin
-     }
-   }
-
-   class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
-   extends EmptyCatchOrFinallyBlock(tryBody, "E001") {
-     val kind = "Syntax"
-     val msg =
-       hl"""|The ${"catch"} block does not contain a valid expression, try
-            |adding a case like - `${"case e: Exception =>"}` to the block""".stripMargin
-   }
-
-   case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context)
-   extends EmptyCatchOrFinallyBlock(tryBody, "E002") {
-     val kind = "Syntax"
-     val msg =
-       hl"""|A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting
-            |its body in a block; no exceptions are handled.""".stripMargin
-   }
+    val explanation = {
+      val tryString = tryBody match {
+        case Block(Nil, untpd.EmptyTree) => "{}"
+        case _ => tryBody.show
+      }
+
+      val code1 =
+        s"""|try $tryString catch {
+            |  case t: Throwable => ???
+            |}""".stripMargin
+
+      val code2 =
+        s"""|try $tryString finally {
+            |  // perform your cleanup here!
+            |}""".stripMargin
+
+      hl"""|A ${"try"} expression should be followed by some mechanism to handle any exceptions
+           |thrown. Typically a ${"catch"} expression follows the ${"try"} and pattern matches
+           |on any expected exceptions. For example:
+           |
+           |$code1
+           |
+           |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
+           |exception propagate - but still allowing for some clean up in ${"finally"}:
+           |
+           |$code2""".stripMargin
+    }
+  }
+
+  class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
+  extends EmptyCatchOrFinallyBlock(tryBody, "E001") {
+    val kind = "Syntax"
+    val msg =
+      hl"""|The ${"catch"} block does not contain a valid expression, try
+           |adding a case like - `${"case e: Exception =>"}` to the block""".stripMargin
+  }
+
+  case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context)
+  extends EmptyCatchOrFinallyBlock(tryBody, "E002") {
+    val kind = "Syntax"
+    val msg =
+      hl"""|A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting
+           |its body in a block; no exceptions are handled.""".stripMargin
+  }
+
+  case class DeprecatedWithOperator()(implicit ctx: Context)
+  extends Message("E003") {
+    val kind = "Syntax"
+    val msg =
+      hl"""${"with"} as a type operator has been deprecated; use `&' instead"""
+    val explanation = {
+      val codeBlock1 =
+        """|trait A {
+           |  type T = Int
+           |}
+           |
+           |trait B {
+           |  type T = Double
+           |}""".stripMargin
+
+      hl"""|Dotty introduces intersection types - `&' types. These replace the
+           |use of the ${"with"} keyword. There are a few differences in
+           |semantics between intersection types and using `${"with"}'.
+           |
+           |`${"A with B"}' is ordered, `${"A & B"}' is not.
+           |
+           |In:
+           |
+           |$codeBlock1
+           |
+           |The type of `${"T"}' in `${"A with B"}' is ${"Int"} whereas in `${"A & B"}'
+           |the type of `${"T"}' is ${"Int & Double"}.""".stripMargin
+    }
+  }
 
   /** Type Errors ----------------------------------------------------------- */
   class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context)
-  extends Message("E003") {
+  extends Message("E004") {
     val kind = "Naming"
     val msg = em"duplicate pattern variable: `${bind.name}`"
 
@@ -172,7 +202,7 @@ object messages {
   }
 
   class MissingIdent(tree: untpd.Ident, treeKind: String, name: Name)(implicit ctx: Context)
-  extends Message("E004") {
+  extends Message("E005") {
     val kind = "Missing identifier"
     val msg = em"not found: $treeKind$name"
 

From af25cb15ca67ac45a13c9b21519efab178409e7d Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 19 Sep 2016 23:13:51 +0200
Subject: [PATCH 26/53] Improve syntax highlighting on polymorphic defs

---
 src/dotty/tools/dotc/printing/SyntaxHighlighting.scala | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 863b089610cb..cdb81d54041a 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -54,7 +54,8 @@ object SyntaxHighlighting {
     'q' :: 'r' :: 's' :: 't' :: 'u' :: 'v' :: 'w' :: 'x' :: 'y' :: 'z' :: Nil
 
   private val typeEnders =
-   '{' :: '}' :: ')' :: '(' :: '=' :: ' ' :: ',' :: '.' :: '\n' :: Nil
+   '{'  :: '}' :: ')' :: '(' :: '[' :: ']' :: '=' :: ' ' :: ',' :: '.' ::
+   '\n' :: Nil
 
   def apply(chars: Iterable[Char]): Iterable[Char] = {
     var prev: Char = 0
@@ -63,7 +64,8 @@ object SyntaxHighlighting {
     var lastToken  = ""
 
     @inline def keywordStart =
-      prev == 0 || prev == ' ' || prev == '{' || prev == '(' || prev == '\n'
+      prev == 0    || prev == ' ' || prev == '{' || prev == '(' ||
+      prev == '\n' || prev == '[' || prev == ','
 
     @inline def numberStart(c: Char) =
       c.isDigit && (!prev.isLetter || prev == '.' || prev == ' ' || prev == '(' || prev == '\u0000')
@@ -258,6 +260,7 @@ object SyntaxHighlighting {
         case ' ' => true
         case '\n' => true
         case '(' => true
+        case '[' => true
         case ':' => true
         case '@' => true
         case _ => false

From 48000c6455694171b554fcb838daae60bc20d6eb Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 20 Sep 2016 09:15:38 +0200
Subject: [PATCH 27/53] Fix underline position

---
 src/dotty/tools/dotc/reporting/ConsoleReporter.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index a5979bd5bcc6..321559e77297 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -40,7 +40,7 @@ class ConsoleReporter(
 
   def columnMarker(pos: SourcePosition, offset: Int)(implicit ctx: Context) =
     if (pos.startLine == pos.endLine) {
-      val whitespace = " " * (pos.column + offset)
+      val whitespace = " " * (pos.startColumn + offset)
       val carets =
         Red("^" * math.max(1, pos.endColumn - pos.startColumn))
 

From f1cc4f2a0c536989402c5ff667d3425e7a6e169d Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 20 Sep 2016 09:50:47 +0200
Subject: [PATCH 28/53] Better operator highlighting

---
 src/dotty/tools/dotc/printing/SyntaxHighlighting.scala | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index cdb81d54041a..6ad29946a80e 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -38,6 +38,7 @@ object SyntaxHighlighting {
   private def typeDef(str: String) = TypeColor + str + NoColor
   private def literal(str: String) = LiteralColor + str + NoColor
   private def valDef(str: String) = ValDefColor + str + NoColor
+  private def operator(str: String) = TypeColor + str + NoColor
   private def annotation(str: String) =
     if (str.trim == "@") str else AnnotationColor + str + NoColor
   private val tripleQs = Console.RED_B + "???" + NoColor
@@ -113,13 +114,13 @@ object SyntaxHighlighting {
               }
             } else newBuf += '/'
           case '='  =>
-            append('=', _ == "=>", keyword)
+            append('=', _ == "=>", operator)
           case '<'  =>
-            append('<', { x => x == "<-" || x == "<:" || x == "<%" }, keyword)
+            append('<', { x => x == "<-" || x == "<:" || x == "<%" }, operator)
           case '>'  =>
-            append('>', { x => x == ">:" }, keyword)
+            append('>', { x => x == ">:" }, operator)
           case '#'  =>
-            if (prev != ' ' && prev != '.') newBuf append keyword("#")
+            if (prev != ' ' && prev != '.') newBuf append operator("#")
             else newBuf += n
             prev = '#'
           case '@'  =>

From 68eae1a27da2ff6be1aa7747205d6e202d9ed781 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 20 Sep 2016 10:39:12 +0200
Subject: [PATCH 29/53] Indent 2 after newline in REPL

---
 src/dotty/tools/dotc/repl/AmmoniteReader.scala               | 4 ++--
 .../tools/dotc/repl/ammonite/filters/BasicFilters.scala      | 5 ++---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/dotty/tools/dotc/repl/AmmoniteReader.scala b/src/dotty/tools/dotc/repl/AmmoniteReader.scala
index 435269081dde..f3b68e4b039d 100644
--- a/src/dotty/tools/dotc/repl/AmmoniteReader.scala
+++ b/src/dotty/tools/dotc/repl/AmmoniteReader.scala
@@ -28,8 +28,8 @@ class AmmoniteReader(val interpreter: Interpreter)(implicit ctx: Context) extend
   val selectionFilter = GUILikeFilters.SelectionFilter(indent = 2)
   val multilineFilter: Filter = Filter("multilineFilter") {
     case TermState(lb ~: rest, b, c, _)
-      if (lb == 10 || lb == 13) && incompleteInput(b.mkString) =>
-      BasicFilters.injectNewLine(b, c, rest)
+    if (lb == 10 || lb == 13) && incompleteInput(b.mkString) =>
+      BasicFilters.injectNewLine(b, c, rest, indent = 2)
   }
 
   def readLine(prompt: String): String = {
diff --git a/src/dotty/tools/dotc/repl/ammonite/filters/BasicFilters.scala b/src/dotty/tools/dotc/repl/ammonite/filters/BasicFilters.scala
index ebbcf214800b..faa97c348cdb 100644
--- a/src/dotty/tools/dotc/repl/ammonite/filters/BasicFilters.scala
+++ b/src/dotty/tools/dotc/repl/ammonite/filters/BasicFilters.scala
@@ -25,12 +25,11 @@ object BasicFilters {
     typingFilter
   )
 
-  def injectNewLine(b: Vector[Char], c: Int, rest: LazyList[Int]) = {
+  def injectNewLine(b: Vector[Char], c: Int, rest: LazyList[Int], indent: Int = 0) = {
     val (first, last) = b.splitAt(c)
-    TermState(rest, (first :+ '\n') ++ last, c + 1)
+    TermState(rest, (first :+ '\n') ++ last ++ Vector.fill(indent)(' '), c + 1 + indent)
   }
 
-
   def navFilter = Filter.merge(
     Case(Up)((b, c, m) => moveUp(b, c, m.width)),
     Case(Down)((b, c, m) => moveDown(b, c, m.width)),

From 6b12f65244964ba740d1a2c2ef7a0b6e3c7b5eb0 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 20 Sep 2016 11:08:18 +0200
Subject: [PATCH 30/53] Fix #1525: start repl if first arg to dotr starts with
 hyphen

---
 bin/dotr | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/bin/dotr b/bin/dotr
index b11712fe9642..8905afd11dd7 100755
--- a/bin/dotr
+++ b/bin/dotr
@@ -29,9 +29,13 @@ function runMain {
     fi
 }
 
+first_arg=$1
+
 if [ -z "$1" ]; then
     echo "Starting dotty REPL..."
     eval "$DOTTY_ROOT/bin/dotc -repl"
+elif [[ ${first_arg:0:1} == "-" ]]; then
+    eval "$DOTTY_ROOT/bin/dotc -repl $@"
 else
     runMain "$@"
 fi

From 153c566d0d6ec8f2e55ab575e1e77f7881629cbc Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 20 Sep 2016 11:23:31 +0200
Subject: [PATCH 31/53] Fix multiple parsing errors on e.g. `try 1`

The `CompilingInterpreter` will on a single compile run, make multiple
parsings of the given line(s). This results in multiple warnings from
the parser. As such, clear the warnings until the actual compile is
performed.
---
 src/dotty/tools/dotc/repl/CompilingInterpreter.scala | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/dotty/tools/dotc/repl/CompilingInterpreter.scala b/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
index 0964de303094..5b3669d5e472 100644
--- a/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
+++ b/src/dotty/tools/dotc/repl/CompilingInterpreter.scala
@@ -212,8 +212,10 @@ class CompilingInterpreter(
       case None => Interpreter.Incomplete
       case Some(Nil) => Interpreter.Error // parse error or empty input
       case Some(tree :: Nil) if tree.isTerm && !tree.isInstanceOf[Assign] =>
+        previousOutput.clear() // clear previous error reporting
         interpret(s"val $newVarName =\n$line")
       case Some(trees) =>
+        previousOutput.clear() // clear previous error reporting
         val req = new Request(line, newLineName)
         if (!req.compile())
           Interpreter.Error // an error happened during compilation, e.g. a type error
@@ -314,9 +316,13 @@ class CompilingInterpreter(
 
   /** One line of code submitted by the user for interpretation */
   private class Request(val line: String, val lineName: String)(implicit ctx: Context) {
-    private val trees = parse(line) match {
-      case Some(ts) => ts
-      case None => Nil
+    private val trees = {
+      val parsed = parse(line)
+      previousOutput.clear() // clear previous error reporting
+      parsed match {
+        case Some(ts) => ts
+        case None => Nil
+      }
     }
 
     /** name to use for the object that will compute "line" */

From 88e41465dd1dcecaa3cd8f0971e8d71e61d48490 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 20 Sep 2016 17:32:23 +0200
Subject: [PATCH 32/53] Add basic diffing for shown values

---
 src/dotty/tools/dotc/util/DiffUtil.scala | 28 +++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/dotty/tools/dotc/util/DiffUtil.scala b/src/dotty/tools/dotc/util/DiffUtil.scala
index b7c77ad62720..8bb39c88aa4c 100644
--- a/src/dotty/tools/dotc/util/DiffUtil.scala
+++ b/src/dotty/tools/dotc/util/DiffUtil.scala
@@ -12,9 +12,7 @@ object DiffUtil {
   private final val DELETION_COLOR = ANSI_RED
   private final val ADDITION_COLOR = ANSI_GREEN
 
-  def mkColoredCodeDiff(code: String, lastCode: String, printDiffDel: Boolean): String = {
-
-    @tailrec def splitTokens(str: String, acc: List[String] = Nil): List[String] = {
+  @tailrec private def splitTokens(str: String, acc: List[String] = Nil): List[String] = {
       if (str == "") {
         acc.reverse
       } else {
@@ -33,6 +31,30 @@ object DiffUtil {
       }
     }
 
+
+  /** @return a tuple of the (found, expected) diffs as strings */
+  def mkColoredTypeDiff(found: String, expected: String): (String, String) = {
+    val foundTokens   = splitTokens(found, Nil).toArray
+    val expectedTokens = splitTokens(expected, Nil).toArray
+
+    val diffExp = hirschberg(foundTokens, expectedTokens)
+    val diffAct = hirschberg(expectedTokens, foundTokens)
+
+    val exp = diffExp.collect {
+      case Unmodified(str) => str
+      case Inserted(str) => ADDITION_COLOR + str + ANSI_DEFAULT
+    }.mkString
+
+    val fnd = diffAct.collect {
+      case Unmodified(str) => str
+      case Inserted(str) => DELETION_COLOR + str + ANSI_DEFAULT
+    }.mkString
+
+    (fnd, exp)
+  }
+
+  def mkColoredCodeDiff(code: String, lastCode: String, printDiffDel: Boolean): String = {
+
     val tokens = splitTokens(code, Nil).toArray
     val lastTokens = splitTokens(lastCode, Nil).toArray
 

From 8743fa86e25133d0ddea3d85d7df0a5ceadef83a Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 22 Sep 2016 11:45:51 +0200
Subject: [PATCH 33/53] Unrainbow syntax highlighting

---
 src/dotty/tools/dotc/printing/SyntaxHighlighting.scala | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 6ad29946a80e..80170dcad8b0 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -92,7 +92,9 @@ object SyntaxHighlighting {
           if (n.isUpper && keywordStart) {
             appendWhile(n, !typeEnders.contains(_), typeDef)
           } else if (keywordStart) {
-            append(n, keywords.contains(_), keyword)
+            append(n, keywords.contains(_), { kw =>
+              if (kw == "new") typeDef(kw) else keyword(kw)
+            })
           } else {
             newBuf += n
             prev = n

From aa559359bb55729913d34588462542f10c42e147 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Wed, 21 Sep 2016 10:09:13 +0200
Subject: [PATCH 34/53] Refactor explanation interpolator

---
 .../tools/dotc/printing/Formatting.scala      | 131 +++++++++++-------
 .../dotc/printing/SyntaxHighlighting.scala    |   2 +-
 .../tools/dotc/reporting/StoreReporter.scala  |   1 -
 .../dotc/reporting/diagnostic/messages.scala  |  27 +++-
 src/dotty/tools/dotc/typer/Applications.scala |  15 +-
 .../tools/dotc/typer/ErrorReporting.scala     |  11 +-
 src/dotty/tools/dotc/typer/RefChecks.scala    |   2 +-
 test/test/TestREPL.scala                      |   4 +-
 tests/repl/errmsgs.check                      |  61 ++++----
 tests/repl/imports.check                      |   8 +-
 10 files changed, 154 insertions(+), 108 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index b39d5683e0c3..89f9eb814714 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -9,6 +9,9 @@ import Decorators._
 import scala.annotation.switch
 import scala.util.control.NonFatal
 import reporting.diagnostic.MessageContainer
+import util.DiffUtil
+import Highlighting.{ highlightToString => _, _ }
+import SyntaxHighlighting._
 
 object Formatting {
 
@@ -113,65 +116,99 @@ object Formatting {
       seen.record(super.polyParamNameString(param), param)
   }
 
-  def explained2(op: Context => String)(implicit ctx: Context): String = {
-    val seen = new Seen
-    val explainCtx = ctx.printer match {
-      case dp: ExplainingPrinter => ctx // re-use outer printer and defer explanation to it
-      case _ => ctx.fresh.setPrinterFn(ctx => new ExplainingPrinter(seen)(ctx))
+  def explanation(entry: Recorded)(implicit ctx: Context): String = {
+    def boundStr(bound: Type, default: ClassSymbol, cmp: String) =
+      if (bound.isRef(default)) "" else i"$cmp $bound"
+
+    def boundsStr(bounds: TypeBounds): String = {
+      val lo = boundStr(bounds.lo, defn.NothingClass, ">:")
+      val hi = boundStr(bounds.hi, defn.AnyClass, "<:")
+      if (lo.isEmpty) hi
+      else if (hi.isEmpty) lo
+      else s"$lo and $hi"
     }
 
-    def explanation(entry: Recorded): String = {
-      def boundStr(bound: Type, default: ClassSymbol, cmp: String) =
-        if (bound.isRef(default)) "" else i"$cmp $bound"
+    def addendum(cat: String, info: Type): String = info match {
+      case bounds @ TypeBounds(lo, hi) if bounds ne TypeBounds.empty =>
+        if (lo eq hi) i" which is an alias of $lo"
+        else i" with $cat ${boundsStr(bounds)}"
+      case _ =>
+        ""
+    }
 
-      def boundsStr(bounds: TypeBounds): String = {
-        val lo = boundStr(bounds.lo, defn.NothingClass, ">:")
-        val hi = boundStr(bounds.hi, defn.AnyClass, "<:")
-        if (lo.isEmpty) hi
-        else if (hi.isEmpty) lo
-        else s"$lo and $hi"
-      }
+    entry match {
+      case param: PolyParam =>
+        s"is a type variable${addendum("constraint", ctx.typeComparer.bounds(param))}"
+      case sym: Symbol =>
+        s"is a ${ctx.printer.kindString(sym)}${sym.showExtendedLocation}${addendum("bounds", sym.info)}"
+    }
+  }
 
-      def addendum(cat: String, info: Type)(implicit ctx: Context): String = info match {
-        case bounds @ TypeBounds(lo, hi) if bounds ne TypeBounds.empty =>
-          if (lo eq hi) i" which is an alias of $lo"
-          else i" with $cat ${boundsStr(bounds)}"
-        case _ =>
-          ""
-      }
+  private def explanations(seen: Seen)(implicit ctx: Context): String = {
+    def needsExplanation(entry: Recorded) = entry match {
+      case param: PolyParam => ctx.typerState.constraint.contains(param)
+      case _ => false
+    }
 
-      entry match {
-        case param: PolyParam =>
-          s"is a type variable${addendum("constraint", ctx.typeComparer.bounds(param))}"
-        case sym: Symbol =>
-          s"is a ${ctx.printer.kindString(sym)}${sym.showExtendedLocation}${addendum("bounds", sym.info)}"
+    val toExplain: List[(String, Recorded)] = seen.toList.flatMap {
+      case (str, entry :: Nil) =>
+        if (needsExplanation(entry)) (str, entry) :: Nil else Nil
+      case (str, entries) =>
+        entries.map(alt => (seen.record(str, alt), alt))
+    }.sortBy(_._1)
+
+    def columnar(parts: List[(String, String)]): List[String] = {
+      lazy val maxLen = parts.map(_._1.length).max
+      parts.map {
+        case (leader, trailer) =>
+          val variable = hl"$leader"
+          s"""$variable${" " * (maxLen - leader.length)} $trailer"""
       }
     }
 
-    def explanations(seen: Seen)(implicit ctx: Context): String = {
-      def needsExplanation(entry: Recorded) = entry match {
-        case param: PolyParam => ctx.typerState.constraint.contains(param)
-        case _ => false
+    val explainParts = toExplain.map { case (str, entry) => (str, explanation(entry)) }
+    val explainLines = columnar(explainParts)
+    if (explainLines.isEmpty) "" else i"$explainLines%\n%\n"
+  }
+
+  private def explainCtx(seen: Seen)(implicit ctx: Context): Context = ctx.printer match {
+    case dp: ExplainingPrinter =>
+      ctx // re-use outer printer and defer explanation to it
+    case _ => ctx.fresh.setPrinterFn(ctx => new ExplainingPrinter(seen)(ctx))
+  }
+
+  def explained2(op: Context => String)(implicit ctx: Context): String = {
+    val seen = new Seen
+    op(explainCtx(seen)) ++ explanations(seen)
+  }
+
+  def disambiguateTypes(args: Type*)(implicit ctx: Context): String = {
+    val seen = new Seen
+    object polyparams extends TypeTraverser {
+      def traverse(tp: Type): Unit = tp match {
+        case tp: TypeRef =>
+          seen.record(tp.show(explainCtx(seen)), tp.symbol)
+          traverseChildren(tp)
+        case tp: TermRef =>
+          seen.record(tp.show(explainCtx(seen)), tp.symbol)
+          traverseChildren(tp)
+        case tp: PolyParam =>
+          seen.record(tp.show(explainCtx(seen)), tp)
+          traverseChildren(tp)
+        case _ =>
+          traverseChildren(tp)
       }
-      val toExplain: List[(String, Recorded)] = seen.toList.flatMap {
-        case (str, entry :: Nil) =>
-          if (needsExplanation(entry)) (str, entry) :: Nil else Nil
-        case (str, entries) =>
-          entries.map(alt => (seen.record(str, alt), alt))
-      }.sortBy(_._1)
-      val explainParts = toExplain.map { case (str, entry) => (str, explanation(entry)) }
-      val explainLines = columnar(explainParts, "  ")
-      if (explainLines.isEmpty) "" else i"\n\nwhere  $explainLines%\n       %\n"
     }
-
-    op(explainCtx) ++ explanations(seen)
+    args.foreach(polyparams.traverse)
+    explanations(seen)
   }
 
-  def columnar(parts: List[(String, String)], sep: String): List[String] = {
-    lazy val maxLen = parts.map(_._1.length).max
-    parts.map {
-      case (leader, trailer) =>
-        s"$leader${" " * (maxLen - leader.length)}$sep$trailer"
+  def typeDiff(found: Type, expected: Type)(implicit ctx: Context): (String, String) = {
+    (found, expected) match {
+      case (rf1: RefinedType, rf2: RefinedType) =>
+        DiffUtil.mkColoredTypeDiff(rf1.show, rf2.show)
+      case _ =>
+        (hl"${found.show}", hl"${expected.show}")
     }
   }
 }
diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 80170dcad8b0..7d4d12394929 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -278,7 +278,7 @@ object SyntaxHighlighting {
       val toAdd  =
         if (shouldHL(str))
           highlight(str)
-        else if (lastToken == "val" || lastToken == "def" || lastToken == "case")
+        else if (("var" :: "val" :: "def" :: "case" :: Nil).contains(lastToken))
           valDef(str)
         else str
       val suffix = if (delim(curr)) s"$curr" else ""
diff --git a/src/dotty/tools/dotc/reporting/StoreReporter.scala b/src/dotty/tools/dotc/reporting/StoreReporter.scala
index 3744a35dd093..e85017ed2bb5 100644
--- a/src/dotty/tools/dotc/reporting/StoreReporter.scala
+++ b/src/dotty/tools/dotc/reporting/StoreReporter.scala
@@ -4,7 +4,6 @@ package reporting
 
 import core.Contexts.Context
 import collection.mutable
-import Reporter.{Error, Warning}
 import config.Printers.typr
 import diagnostic.MessageContainer
 import diagnostic.messages._
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index cf67e8989549..00963659377a 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -4,12 +4,13 @@ package reporting
 package diagnostic
 
 import dotc.core._
-import Contexts.Context, Decorators._, Symbols._, Names._
+import Contexts.Context, Decorators._, Symbols._, Names._, Types._
 import util.{SourceFile, NoSource}
 import util.{SourcePosition, NoSourcePosition}
 import config.Settings.Setting
 import interfaces.Diagnostic.{ERROR, WARNING, INFO}
-import dotc.printing.SyntaxHighlighting._
+import printing.SyntaxHighlighting._
+import printing.Formatting
 
 object messages {
 
@@ -127,7 +128,7 @@ object messages {
     }
   }
 
-  class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
+  case class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
   extends EmptyCatchOrFinallyBlock(tryBody, "E001") {
     val kind = "Syntax"
     val msg =
@@ -174,7 +175,7 @@ object messages {
   }
 
   /** Type Errors ----------------------------------------------------------- */
-  class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context)
+  case class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context)
   extends Message("E004") {
     val kind = "Naming"
     val msg = em"duplicate pattern variable: `${bind.name}`"
@@ -201,9 +202,9 @@ object messages {
     }
   }
 
-  class MissingIdent(tree: untpd.Ident, treeKind: String, name: Name)(implicit ctx: Context)
+  case class MissingIdent(tree: untpd.Ident, treeKind: String, name: Name)(implicit ctx: Context)
   extends Message("E005") {
-    val kind = "Missing identifier"
+    val kind = "Missing Identifier"
     val msg = em"not found: $treeKind$name"
 
     val explanation = {
@@ -211,4 +212,18 @@ object messages {
            |has either been misspelt or you're forgetting an import""".stripMargin
     }
   }
+
+  case class TypeMismatch(found: Type, expected: Type, whyNoMatch: String = "")(implicit ctx: Context)
+  extends Message("E006") {
+    val kind = "Type Mismatch"
+    private val where = Formatting.disambiguateTypes(found, expected)
+    private val (fnd, exp) = Formatting.typeDiff(found, expected)
+    val msg =
+      s"""|found:    $fnd
+          |required: $exp
+          |
+          |$where""".stripMargin + whyNoMatch
+
+    val explanation = ""
+  }
 }
diff --git a/src/dotty/tools/dotc/typer/Applications.scala b/src/dotty/tools/dotc/typer/Applications.scala
index 2c9039db1fc4..56595a637e75 100644
--- a/src/dotty/tools/dotc/typer/Applications.scala
+++ b/src/dotty/tools/dotc/typer/Applications.scala
@@ -27,6 +27,7 @@ import collection.mutable
 import config.Printers.{typr, unapp, overload}
 import TypeApplications._
 import language.implicitConversions
+import reporting.diagnostic.Message
 
 object Applications {
   import tpd._
@@ -132,10 +133,10 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
     protected def harmonizeArgs(args: List[TypedArg]): List[TypedArg]
 
     /** Signal failure with given message at position of given argument */
-    protected def fail(msg: => String, arg: Arg): Unit
+    protected def fail(msg: => Message, arg: Arg): Unit
 
     /** Signal failure with given message at position of the application itself */
-    protected def fail(msg: => String): Unit
+    protected def fail(msg: => Message): Unit
 
     protected def appPos: Position
 
@@ -186,7 +187,7 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
               // it might be healed by an implicit conversion
               assert(ctx.typerState.constraint eq savedConstraint)
             else
-              fail(err.typeMismatchStr(methType.resultType, resultType))
+              fail(err.typeMismatchMsg(methType.resultType, resultType))
         }
         // match all arguments with corresponding formal parameters
         matchArgs(orderedArgs, methType.paramTypes, 0)
@@ -388,9 +389,9 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
     def addArg(arg: TypedArg, formal: Type) =
       ok = ok & isCompatible(argType(arg, formal), formal)
     def makeVarArg(n: Int, elemFormal: Type) = {}
-    def fail(msg: => String, arg: Arg) =
+    def fail(msg: => Message, arg: Arg) =
       ok = false
-    def fail(msg: => String) =
+    def fail(msg: => Message) =
       ok = false
     def appPos = NoPosition
     lazy val normalizedFun = ref(methRef)
@@ -455,12 +456,12 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
 
     override def appPos = app.pos
 
-    def fail(msg: => String, arg: Trees.Tree[T]) = {
+    def fail(msg: => Message, arg: Trees.Tree[T]) = {
       ctx.error(msg, arg.pos)
       ok = false
     }
 
-    def fail(msg: => String) = {
+    def fail(msg: => Message) = {
       ctx.error(msg, app.pos)
       ok = false
     }
diff --git a/src/dotty/tools/dotc/typer/ErrorReporting.scala b/src/dotty/tools/dotc/typer/ErrorReporting.scala
index 8b740c3dc656..1fd4fc96e1a7 100644
--- a/src/dotty/tools/dotc/typer/ErrorReporting.scala
+++ b/src/dotty/tools/dotc/typer/ErrorReporting.scala
@@ -12,12 +12,13 @@ import printing.{Showable, RefinedPrinter}
 import scala.collection.mutable
 import java.util.regex.Matcher.quoteReplacement
 import reporting.diagnostic.Message
+import reporting.diagnostic.messages._
 
 object ErrorReporting {
 
   import tpd._
 
-  def errorTree(tree: untpd.Tree, msg: => String)(implicit ctx: Context): tpd.Tree =
+  def errorTree(tree: untpd.Tree, msg: => Message)(implicit ctx: Context): tpd.Tree =
     tree withType errorType(msg, tree.pos)
 
   def errorType(msg: => Message, pos: Position)(implicit ctx: Context): ErrorType = {
@@ -101,7 +102,7 @@ object ErrorReporting {
     def patternConstrStr(tree: Tree): String = ???
 
     def typeMismatch(tree: Tree, pt: Type, implicitFailure: SearchFailure = NoImplicitMatches): Tree =
-      errorTree(tree, typeMismatchStr(normalize(tree.tpe, pt), pt) + implicitFailure.postscript)
+      errorTree(tree, typeMismatchMsg(normalize(tree.tpe, pt), pt) /*+ implicitFailure.postscript*/)
 
     /** A subtype log explaining why `found` does not conform to `expected` */
     def whyNoMatchStr(found: Type, expected: Type) =
@@ -110,7 +111,7 @@ object ErrorReporting {
       else
         ""
 
-    def typeMismatchStr(found: Type, expected: Type) = {
+    def typeMismatchMsg(found: Type, expected: Type) = {
       // replace constrained polyparams and their typevars by their bounds where possible
       object reported extends TypeMap {
         def setVariance(v: Int) = variance = v
@@ -132,9 +133,7 @@ object ErrorReporting {
       val found1 = reported(found)
       reported.setVariance(-1)
       val expected1 = reported(expected)
-      ex"""|type mismatch:
-           |found:    $found1
-           |required: $expected1""".stripMargin + whyNoMatchStr(found, expected)
+      TypeMismatch(found1, expected1, whyNoMatchStr(found, expected))
     }
 
     /** Format `raw` implicitNotFound argument, replacing all
diff --git a/src/dotty/tools/dotc/typer/RefChecks.scala b/src/dotty/tools/dotc/typer/RefChecks.scala
index 1f150c5192c7..4d82a2d12ce0 100644
--- a/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -200,7 +200,7 @@ object RefChecks {
               infoStringWithLocation(other),
               infoStringWithLocation(member))
           else if (ctx.settings.debug.value)
-            err.typeMismatchStr(memberTp, otherTp)
+            err.typeMismatchMsg(memberTp, otherTp)
           else ""
 
         "overriding %s;\n %s %s%s".format(
diff --git a/test/test/TestREPL.scala b/test/test/TestREPL.scala
index 090c774bb7d6..9867cb4ecf20 100644
--- a/test/test/TestREPL.scala
+++ b/test/test/TestREPL.scala
@@ -21,9 +21,7 @@ class TestREPL(script: String) extends REPL {
     override val output = new NewLinePrintWriter(out)
 
     override def context(ctx: Context) =
-      ctx.fresh
-        .setSetting(ctx.settings.color, "never")
-        .setSetting(ctx.settings.pageWidth, 80)
+      ctx.fresh.setSetting(ctx.settings.color, "never")
 
     override def input(in: Interpreter)(implicit ctx: Context) = new InteractiveReader {
       val lines = script.lines.buffered
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index d8c1b9215e74..8f86aac083c7 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -1,48 +1,47 @@
 scala> class Inv[T](x: T)
 defined class Inv
 scala> val x: List[String] = List(1)
--- Error: <console> ------------------------------------------------------------
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val x: List[String] = List(1)
                              ^
-                             type mismatch:
                              found:    Int(1)
                              required: String
+                             
 scala> val y: List[List[String]] = List(List(1))
--- Error: <console> ------------------------------------------------------------
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val y: List[List[String]] = List(List(1))
                                         ^
-                                        type mismatch:
                                         found:    Int(1)
                                         required: String
+                                        
 scala> val z: (List[String], List[Int]) = (List(1), List("a"))
--- Error: <console> ------------------------------------------------------------
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val z: (List[String], List[Int]) = (List(1), List("a"))
                                            ^
-                                           type mismatch:
                                            found:    Int(1)
                                            required: String
--- Error: <console> ------------------------------------------------------------
+                                           
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val z: (List[String], List[Int]) = (List(1), List("a"))
-                                                    ^
-                                                    type mismatch:
+                                                    ^^^
                                                     found:    String("a")
                                                     required: Int
+                                                    
 scala> val a: Inv[String] = new Inv(new Inv(1))
--- Error: <console> ------------------------------------------------------------
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4:val a: Inv[String] = new Inv(new Inv(1))
-                                   ^^^^
-                        type mismatch:
-                        found:    Inv[T]
-                        required: String
-                        
-                        where  T  is a type variable with constraint >: Int(1)
+                                   ^^^^^
+                                   found:    Inv[T]
+                                   required: String
+                                   
+                                   T is a type variable with constraint >: Int(1)
 scala> val b: Inv[String] = new Inv(1)
--- Error: <console> ------------------------------------------------------------
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4:val b: Inv[String] = new Inv(1)
                                ^
-                               type mismatch:
                                found:    Int(1)
                                required: String
+                               
 scala> abstract class C {
            type T
            val x: T
@@ -58,22 +57,20 @@ scala> abstract class C {
              }
            }
          }
--- Error: <console> ------------------------------------------------------------
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 8:      var y: T = x
                    ^
- type mismatch:
- found:    C.this.T(C.this.x)
- required: T'
- 
- where  T   is a type in class C
-        T'  is a type in the initalizer of value s which is an alias of String
--- Error: <console> ------------------------------------------------------------
+                   found:    C.this.T(C.this.x)
+                   required: T
+                   
+                   T  is a type in class C
+                   T' is a type in the initalizer of value s which is an alias of String
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 12:          val z: T = y
                         ^
-type mismatch:
-found:    T(y)
-required: T'
-
-where  T   is a type in the initalizer of value s which is an alias of String
-       T'  is a type in method f which is an alias of Int
+                        found:    T(y)
+                        required: T
+                        
+                        T  is a type in the initalizer of value s which is an alias of String
+                        T' is a type in method f which is an alias of Int
 scala> :quit
diff --git a/tests/repl/imports.check b/tests/repl/imports.check
index f9e48c0119a1..2e8d5dcf967f 100644
--- a/tests/repl/imports.check
+++ b/tests/repl/imports.check
@@ -7,18 +7,18 @@ defined module o
 scala> import o._
 import o._
 scala> buf += xs
--- Error: <console> ------------------------------------------------------------
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 10:buf += xs
           ^^
-          type mismatch:
           found:    scala.collection.immutable.List[Int](o.xs)
           required: String
--- Error: <console> ------------------------------------------------------------
+          
+-- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 10:buf += xs
    ^^^^^^^^^
-   type mismatch:
    found:    String
    required: scala.collection.mutable.ListBuffer[Int]
+   
 scala> buf ++= xs
 res1: scala.collection.mutable.ListBuffer[Int] = ListBuffer(1, 2, 3)
 scala> :quit

From 33d44903ec95cff9b79523683175733fd49ba140 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 26 Sep 2016 13:40:59 +0200
Subject: [PATCH 35/53] Make `typeDiff` aware of placeholder types

---
 .../tools/dotc/printing/Formatting.scala      | 55 ++++++++++++-------
 .../dotc/reporting/diagnostic/messages.scala  |  4 +-
 tests/repl/errmsgs.check                      | 14 ++---
 3 files changed, 45 insertions(+), 28 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index 89f9eb814714..dd391ea80cf6 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -116,6 +116,7 @@ object Formatting {
       seen.record(super.polyParamNameString(param), param)
   }
 
+  /** Create explanation for single `Recorded` type or symbol */
   def explanation(entry: Recorded)(implicit ctx: Context): String = {
     def boundStr(bound: Type, default: ClassSymbol, cmp: String) =
       if (bound.isRef(default)) "" else i"$cmp $bound"
@@ -144,6 +145,7 @@ object Formatting {
     }
   }
 
+  /** Turns a `Seen => String` to produce a `where: T is...` clause */
   private def explanations(seen: Seen)(implicit ctx: Context): String = {
     def needsExplanation(entry: Recorded) = entry match {
       case param: PolyParam => ctx.typerState.constraint.contains(param)
@@ -168,41 +170,56 @@ object Formatting {
 
     val explainParts = toExplain.map { case (str, entry) => (str, explanation(entry)) }
     val explainLines = columnar(explainParts)
-    if (explainLines.isEmpty) "" else i"$explainLines%\n%\n"
+    if (explainLines.isEmpty) "" else i"where:    $explainLines%\n          %\n"
   }
 
+  /** Context with correct printer set for explanations */
   private def explainCtx(seen: Seen)(implicit ctx: Context): Context = ctx.printer match {
     case dp: ExplainingPrinter =>
       ctx // re-use outer printer and defer explanation to it
     case _ => ctx.fresh.setPrinterFn(ctx => new ExplainingPrinter(seen)(ctx))
   }
 
+  /** Entrypoint for explanation string interpolator:
+    *
+    * ```
+    * ex"disambiguate $tpe1 and $tpe2"
+    * ```
+    */
   def explained2(op: Context => String)(implicit ctx: Context): String = {
     val seen = new Seen
     op(explainCtx(seen)) ++ explanations(seen)
   }
 
-  def disambiguateTypes(args: Type*)(implicit ctx: Context): String = {
+  /** When getting a type mismatch it is useful to disambiguate placeholders like:
+    *
+    * ```
+    * found:    List[Int]
+    * required: List[T]
+    * where:    T is a type in the initalizer of value s which is an alias of
+    *           String
+    * ```
+    *
+    * @return the `where` section as well as the printing context for the
+    *         placeholders - `("T is a...", printCtx)`
+    */
+  def disambiguateTypes(args: Type*)(implicit ctx: Context): (String, Context) = {
     val seen = new Seen
-    object polyparams extends TypeTraverser {
-      def traverse(tp: Type): Unit = tp match {
-        case tp: TypeRef =>
-          seen.record(tp.show(explainCtx(seen)), tp.symbol)
-          traverseChildren(tp)
-        case tp: TermRef =>
-          seen.record(tp.show(explainCtx(seen)), tp.symbol)
-          traverseChildren(tp)
-        case tp: PolyParam =>
-          seen.record(tp.show(explainCtx(seen)), tp)
-          traverseChildren(tp)
-        case _ =>
-          traverseChildren(tp)
-      }
-    }
-    args.foreach(polyparams.traverse)
-    explanations(seen)
+    val printCtx = explainCtx(seen)
+    args.foreach(_.show(printCtx)) // showing each member will put it into `seen`
+    (explanations(seen), printCtx)
   }
 
+  /** This method will produce a colored type diff from the given arguments.
+    * The idea is to do this for known cases that are useful and then fall back
+    * on regular syntax highlighting for the cases which are unhandled.
+    *
+    * Please not that if used in combination with `disambiguateTypes` the
+    * correct `Context` for printing should also be passed when calling the
+    * method.
+    *
+    * @return the (found, expected) with coloring to highlight the difference
+    */
   def typeDiff(found: Type, expected: Type)(implicit ctx: Context): (String, String) = {
     (found, expected) match {
       case (rf1: RefinedType, rf2: RefinedType) =>
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 00963659377a..01cf00cf74a4 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -216,8 +216,8 @@ object messages {
   case class TypeMismatch(found: Type, expected: Type, whyNoMatch: String = "")(implicit ctx: Context)
   extends Message("E006") {
     val kind = "Type Mismatch"
-    private val where = Formatting.disambiguateTypes(found, expected)
-    private val (fnd, exp) = Formatting.typeDiff(found, expected)
+    private val (where, printCtx) = Formatting.disambiguateTypes(found, expected)
+    private val (fnd, exp) = Formatting.typeDiff(found, expected)(printCtx)
     val msg =
       s"""|found:    $fnd
           |required: $exp
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index 8f86aac083c7..b8cff5ba2df6 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -34,7 +34,7 @@ scala> val a: Inv[String] = new Inv(new Inv(1))
                                    found:    Inv[T]
                                    required: String
                                    
-                                   T is a type variable with constraint >: Int(1)
+                                   where:    T is a type variable with constraint >: Int(1)
 scala> val b: Inv[String] = new Inv(1)
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4:val b: Inv[String] = new Inv(1)
@@ -61,16 +61,16 @@ scala> abstract class C {
 8:      var y: T = x
                    ^
                    found:    C.this.T(C.this.x)
-                   required: T
+                   required: T'
                    
-                   T  is a type in class C
-                   T' is a type in the initalizer of value s which is an alias of String
+                   where:    T  is a type in class C
+                             T' is a type in the initalizer of value s which is an alias of String
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 12:          val z: T = y
                         ^
                         found:    T(y)
-                        required: T
+                        required: T'
                         
-                        T  is a type in the initalizer of value s which is an alias of String
-                        T' is a type in method f which is an alias of Int
+                        where:    T  is a type in the initalizer of value s which is an alias of String
+                                  T' is a type in method f which is an alias of Int
 scala> :quit

From 24bcdfdcdaa04e3cf2aa3c7289415f8a98d3d376 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 27 Sep 2016 12:59:08 +0200
Subject: [PATCH 36/53] Add `dotty.jar` to gitignore

---
 .gitignore | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.gitignore b/.gitignore
index 17eba04681ba..416a12effd24 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,7 +3,6 @@
 *.log
 *.swp
 *~
-*.swp
 
 # sbt specific
 dist/*
@@ -29,6 +28,7 @@ classes/
 /.worksheet/
 
 # Partest
+dotty.jar
 tests/partest-generated/
 tests/locks/
 /test-classes/

From f5ad8492d076051c8805370c05610d8294ccb241 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 27 Sep 2016 16:07:56 +0200
Subject: [PATCH 37/53] Fix reporting of ErrorTypes in highlighted segments

---
 src/dotty/tools/dotc/core/Decorators.scala    |  4 ++
 .../tools/dotc/printing/Formatting.scala      | 50 +++++++++++++------
 .../dotc/printing/SyntaxHighlighting.scala    | 14 ------
 .../dotc/reporting/ConsoleReporter.scala      |  2 +-
 .../diagnostic/MessageContainer.scala         |  2 +-
 .../dotc/reporting/diagnostic/messages.scala  |  4 +-
 src/dotty/tools/dotc/typer/Typer.scala        |  2 +-
 tests/repl/errmsgs.check                      | 16 +++---
 tests/repl/imports.check                      |  4 +-
 9 files changed, 55 insertions(+), 43 deletions(-)

diff --git a/src/dotty/tools/dotc/core/Decorators.scala b/src/dotty/tools/dotc/core/Decorators.scala
index 3bf17730a9f9..b0f1f0c98c5d 100644
--- a/src/dotty/tools/dotc/core/Decorators.scala
+++ b/src/dotty/tools/dotc/core/Decorators.scala
@@ -176,6 +176,10 @@ object Decorators {
      */
     def ex(args: Any*)(implicit ctx: Context): String =
       explained2(implicit ctx => em(args: _*))
+
+    /** Formatter that adds syntax highlighting to all interpolated values */
+    def hl(args: Any*)(implicit ctx: Context): String =
+      new SyntaxFormatter(sc).assemble(args)
   }
 }
 
diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index dd391ea80cf6..41bd91607ea7 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -69,21 +69,40 @@ object Formatting {
    *  message composition methods, this is crucial.
    */
   class ErrorMessageFormatter(sc: StringContext) extends StringFormatter(sc) {
+    override protected def showArg(arg: Any)(implicit ctx: Context): String =
+      wrapNonSensical(arg, super.showArg(arg))
+  }
+
+  class SyntaxFormatter(sc: StringContext) extends StringFormatter(sc) {
     override protected def showArg(arg: Any)(implicit ctx: Context): String = {
-      import MessageContainer._
-      def isSensical(arg: Any): Boolean = arg match {
-        case tpe: Type =>
-          tpe.exists && !tpe.isErroneous
-        case sym: Symbol if sym.isCompleted =>
-          sym.info != ErrorType && sym.info != TypeAlias(ErrorType) && sym.info.exists
-        case _ => true
+      arg match {
+        case arg: Showable =>
+          val highlighted =
+            SyntaxHighlighting(wrapNonSensical(arg, super.showArg(arg)))
+          new String(highlighted.toArray)
+        case hl: Highlight =>
+          hl.show
+        case hb: HighlightBuffer =>
+          hb.toString
+        case _ => super.showArg(arg)
       }
-      val str = super.showArg(arg)
-      if (isSensical(arg)) str
-      else nonSensicalStartTag + str + nonSensicalEndTag
     }
   }
 
+  private def wrapNonSensical(arg: Any, str: String)(implicit ctx: Context): String = {
+    import MessageContainer._
+    def isSensical(arg: Any): Boolean = arg match {
+      case tpe: Type =>
+        tpe.exists && !tpe.isErroneous
+      case sym: Symbol if sym.isCompleted =>
+        sym.info != ErrorType && sym.info != TypeAlias(ErrorType) && sym.info.exists
+      case _ => true
+    }
+
+    if (isSensical(arg)) str
+    else nonSensicalStartTag + str + nonSensicalEndTag
+  }
+
   private type Recorded = AnyRef /*Symbol | PolyParam*/
 
   private class Seen extends mutable.HashMap[String, List[Recorded]] {
@@ -117,7 +136,7 @@ object Formatting {
   }
 
   /** Create explanation for single `Recorded` type or symbol */
-  def explanation(entry: Recorded)(implicit ctx: Context): String = {
+  def explanation(entry: AnyRef)(implicit ctx: Context): String = {
     def boundStr(bound: Type, default: ClassSymbol, cmp: String) =
       if (bound.isRef(default)) "" else i"$cmp $bound"
 
@@ -221,11 +240,14 @@ object Formatting {
     * @return the (found, expected) with coloring to highlight the difference
     */
   def typeDiff(found: Type, expected: Type)(implicit ctx: Context): (String, String) = {
+    val fnd = wrapNonSensical(found, found.show)
+    val exp = wrapNonSensical(expected, found.show)
+
     (found, expected) match {
-      case (rf1: RefinedType, rf2: RefinedType) =>
-        DiffUtil.mkColoredTypeDiff(rf1.show, rf2.show)
+      case (_: RefinedType, _: RefinedType) =>
+        DiffUtil.mkColoredTypeDiff(fnd, exp)
       case _ =>
-        (hl"${found.show}", hl"${expected.show}")
+        (hl"$fnd", hl"$exp")
     }
   }
 }
diff --git a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
index 7d4d12394929..86f34e64d451 100644
--- a/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
+++ b/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala
@@ -11,20 +11,6 @@ import Highlighting.{Highlight, HighlightBuffer}
 /** This object provides functions for syntax highlighting in the REPL */
 object SyntaxHighlighting {
 
-  implicit class SyntaxFormatting(val sc: StringContext) extends AnyVal {
-    def hl(args: Any*)(implicit ctx: Context): String =
-      sc.s(args.map ({
-        case hl: Highlight =>
-          hl.show
-        case hb: HighlightBuffer =>
-          hb.toString
-        case x if ctx.settings.color.value != "never" =>
-          new String(apply(x.toString).toArray)
-        case x =>
-          x.toString
-      }): _*)
-  }
-
   val NoColor         = Console.RESET
   val CommentColor    = Console.BLUE
   val KeywordColor    = Console.YELLOW
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 321559e77297..261357924af5 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -4,7 +4,7 @@ package reporting
 
 import scala.collection.mutable
 import util.SourcePosition
-import core.Contexts._
+import core.Contexts._, core.Decorators._
 import Reporter._
 import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
index d15c1d2f1f8e..7bb092da222d 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
@@ -41,7 +41,7 @@ class MessageContainer(
   /** The message to report */
   def message: String = {
     if (myMsg == null) {
-      myMsg = msgFn.msg
+      myMsg = msgFn.msg.replaceAll("\u001B\\[[;\\d]*m", "")
       if (myMsg.contains(nonSensicalStartTag)) {
         myIsNonSensical = true
         // myMsg might be composed of several d"..." invocations -> nested
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 01cf00cf74a4..76b2fd3e9521 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -202,13 +202,13 @@ object messages {
     }
   }
 
-  case class MissingIdent(tree: untpd.Ident, treeKind: String, name: Name)(implicit ctx: Context)
+  case class MissingIdent(tree: untpd.Ident, treeKind: String, name: String)(implicit ctx: Context)
   extends Message("E005") {
     val kind = "Missing Identifier"
     val msg = em"not found: $treeKind$name"
 
     val explanation = {
-      hl"""|An identifier for `${name.show}` is missing. This means that something
+      hl"""|An identifier for `$treeKind$name` is missing. This means that something
            |has either been misspelt or you're forgetting an import""".stripMargin
     }
   }
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 0cc04613ad7a..a4dc2f87138d 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -331,7 +331,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
       if (rawType.exists)
         ensureAccessible(rawType, superAccess = false, tree.pos)
       else {
-        error(new MissingIdent(tree, kind, name), tree.pos)
+        error(new MissingIdent(tree, kind, name.show), tree.pos)
         ErrorType
       }
 
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index b8cff5ba2df6..b791123f4366 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -5,34 +5,34 @@ scala> val x: List[String] = List(1)
 3:val x: List[String] = List(1)
                              ^
                              found:    Int(1)
-                             required: String
+                             required: Int(1)
                              
 scala> val y: List[List[String]] = List(List(1))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val y: List[List[String]] = List(List(1))
                                         ^
                                         found:    Int(1)
-                                        required: String
+                                        required: Int(1)
                                         
 scala> val z: (List[String], List[Int]) = (List(1), List("a"))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val z: (List[String], List[Int]) = (List(1), List("a"))
                                            ^
                                            found:    Int(1)
-                                           required: String
+                                           required: Int(1)
                                            
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val z: (List[String], List[Int]) = (List(1), List("a"))
                                                     ^^^
                                                     found:    String("a")
-                                                    required: Int
+                                                    required: String("a")
                                                     
 scala> val a: Inv[String] = new Inv(new Inv(1))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4:val a: Inv[String] = new Inv(new Inv(1))
                                    ^^^^^
                                    found:    Inv[T]
-                                   required: String
+                                   required: Inv[T]
                                    
                                    where:    T is a type variable with constraint >: Int(1)
 scala> val b: Inv[String] = new Inv(1)
@@ -40,7 +40,7 @@ scala> val b: Inv[String] = new Inv(1)
 4:val b: Inv[String] = new Inv(1)
                                ^
                                found:    Int(1)
-                               required: String
+                               required: Int(1)
                                
 scala> abstract class C {
            type T
@@ -61,7 +61,7 @@ scala> abstract class C {
 8:      var y: T = x
                    ^
                    found:    C.this.T(C.this.x)
-                   required: T'
+                   required: C.this.T(C.this.x)
                    
                    where:    T  is a type in class C
                              T' is a type in the initalizer of value s which is an alias of String
@@ -69,7 +69,7 @@ scala> abstract class C {
 12:          val z: T = y
                         ^
                         found:    T(y)
-                        required: T'
+                        required: T(y)
                         
                         where:    T  is a type in the initalizer of value s which is an alias of String
                                   T' is a type in method f which is an alias of Int
diff --git a/tests/repl/imports.check b/tests/repl/imports.check
index 2e8d5dcf967f..817adae87bf9 100644
--- a/tests/repl/imports.check
+++ b/tests/repl/imports.check
@@ -11,13 +11,13 @@ scala> buf += xs
 10:buf += xs
           ^^
           found:    scala.collection.immutable.List[Int](o.xs)
-          required: String
+          required: scala.collection.immutable.List[Int](o.xs)
           
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 10:buf += xs
    ^^^^^^^^^
    found:    String
-   required: scala.collection.mutable.ListBuffer[Int]
+   required: String
    
 scala> buf ++= xs
 res1: scala.collection.mutable.ListBuffer[Int] = ListBuffer(1, 2, 3)

From a7d3f6e1b85f772bb343c5d006fd1e4edc844a93 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 27 Sep 2016 16:52:30 +0200
Subject: [PATCH 38/53] Don't force Message twice in MessageContainer

---
 src/dotty/tools/dotc/printing/Formatting.scala                  | 2 +-
 .../tools/dotc/reporting/diagnostic/MessageContainer.scala      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index 41bd91607ea7..ae3819513577 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -241,7 +241,7 @@ object Formatting {
     */
   def typeDiff(found: Type, expected: Type)(implicit ctx: Context): (String, String) = {
     val fnd = wrapNonSensical(found, found.show)
-    val exp = wrapNonSensical(expected, found.show)
+    val exp = wrapNonSensical(expected, expected.show)
 
     (found, expected) match {
       case (_: RefinedType, _: RefinedType) =>
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
index 7bb092da222d..a1a99f17d3a6 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
@@ -41,7 +41,7 @@ class MessageContainer(
   /** The message to report */
   def message: String = {
     if (myMsg == null) {
-      myMsg = msgFn.msg.replaceAll("\u001B\\[[;\\d]*m", "")
+      myMsg = contained.msg.replaceAll("\u001B\\[[;\\d]*m", "")
       if (myMsg.contains(nonSensicalStartTag)) {
         myIsNonSensical = true
         // myMsg might be composed of several d"..." invocations -> nested

From 7561db09c19bff7871cfd96c327f6f7882480ebd Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 27 Sep 2016 17:27:59 +0200
Subject: [PATCH 39/53] Fix TypeMismatch not getting nonsensical tags in some
 cases

Thanks @smarter!
---
 .../dotc/reporting/diagnostic/messages.scala     |  4 ++--
 src/dotty/tools/dotc/typer/ErrorReporting.scala  |  6 +++---
 tests/repl/errmsgs.check                         | 16 ++++++++--------
 tests/repl/imports.check                         |  4 ++--
 4 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 76b2fd3e9521..034e14267635 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -213,7 +213,7 @@ object messages {
     }
   }
 
-  case class TypeMismatch(found: Type, expected: Type, whyNoMatch: String = "")(implicit ctx: Context)
+  case class TypeMismatch(found: Type, expected: Type, whyNoMatch: String = "", implicitFailure: String = "")(implicit ctx: Context)
   extends Message("E006") {
     val kind = "Type Mismatch"
     private val (where, printCtx) = Formatting.disambiguateTypes(found, expected)
@@ -222,7 +222,7 @@ object messages {
       s"""|found:    $fnd
           |required: $exp
           |
-          |$where""".stripMargin + whyNoMatch
+          |$where""".stripMargin + whyNoMatch + implicitFailure
 
     val explanation = ""
   }
diff --git a/src/dotty/tools/dotc/typer/ErrorReporting.scala b/src/dotty/tools/dotc/typer/ErrorReporting.scala
index 1fd4fc96e1a7..1d22dc6465ed 100644
--- a/src/dotty/tools/dotc/typer/ErrorReporting.scala
+++ b/src/dotty/tools/dotc/typer/ErrorReporting.scala
@@ -102,7 +102,7 @@ object ErrorReporting {
     def patternConstrStr(tree: Tree): String = ???
 
     def typeMismatch(tree: Tree, pt: Type, implicitFailure: SearchFailure = NoImplicitMatches): Tree =
-      errorTree(tree, typeMismatchMsg(normalize(tree.tpe, pt), pt) /*+ implicitFailure.postscript*/)
+      errorTree(tree, typeMismatchMsg(normalize(tree.tpe, pt), pt, implicitFailure.postscript))
 
     /** A subtype log explaining why `found` does not conform to `expected` */
     def whyNoMatchStr(found: Type, expected: Type) =
@@ -111,7 +111,7 @@ object ErrorReporting {
       else
         ""
 
-    def typeMismatchMsg(found: Type, expected: Type) = {
+    def typeMismatchMsg(found: Type, expected: Type, postScript: String = "") = {
       // replace constrained polyparams and their typevars by their bounds where possible
       object reported extends TypeMap {
         def setVariance(v: Int) = variance = v
@@ -133,7 +133,7 @@ object ErrorReporting {
       val found1 = reported(found)
       reported.setVariance(-1)
       val expected1 = reported(expected)
-      TypeMismatch(found1, expected1, whyNoMatchStr(found, expected))
+      TypeMismatch(found1, expected1, whyNoMatchStr(found, expected), postScript)
     }
 
     /** Format `raw` implicitNotFound argument, replacing all
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index b791123f4366..b8cff5ba2df6 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -5,34 +5,34 @@ scala> val x: List[String] = List(1)
 3:val x: List[String] = List(1)
                              ^
                              found:    Int(1)
-                             required: Int(1)
+                             required: String
                              
 scala> val y: List[List[String]] = List(List(1))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val y: List[List[String]] = List(List(1))
                                         ^
                                         found:    Int(1)
-                                        required: Int(1)
+                                        required: String
                                         
 scala> val z: (List[String], List[Int]) = (List(1), List("a"))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val z: (List[String], List[Int]) = (List(1), List("a"))
                                            ^
                                            found:    Int(1)
-                                           required: Int(1)
+                                           required: String
                                            
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 3:val z: (List[String], List[Int]) = (List(1), List("a"))
                                                     ^^^
                                                     found:    String("a")
-                                                    required: String("a")
+                                                    required: Int
                                                     
 scala> val a: Inv[String] = new Inv(new Inv(1))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4:val a: Inv[String] = new Inv(new Inv(1))
                                    ^^^^^
                                    found:    Inv[T]
-                                   required: Inv[T]
+                                   required: String
                                    
                                    where:    T is a type variable with constraint >: Int(1)
 scala> val b: Inv[String] = new Inv(1)
@@ -40,7 +40,7 @@ scala> val b: Inv[String] = new Inv(1)
 4:val b: Inv[String] = new Inv(1)
                                ^
                                found:    Int(1)
-                               required: Int(1)
+                               required: String
                                
 scala> abstract class C {
            type T
@@ -61,7 +61,7 @@ scala> abstract class C {
 8:      var y: T = x
                    ^
                    found:    C.this.T(C.this.x)
-                   required: C.this.T(C.this.x)
+                   required: T'
                    
                    where:    T  is a type in class C
                              T' is a type in the initalizer of value s which is an alias of String
@@ -69,7 +69,7 @@ scala> abstract class C {
 12:          val z: T = y
                         ^
                         found:    T(y)
-                        required: T(y)
+                        required: T'
                         
                         where:    T  is a type in the initalizer of value s which is an alias of String
                                   T' is a type in method f which is an alias of Int
diff --git a/tests/repl/imports.check b/tests/repl/imports.check
index 817adae87bf9..2e8d5dcf967f 100644
--- a/tests/repl/imports.check
+++ b/tests/repl/imports.check
@@ -11,13 +11,13 @@ scala> buf += xs
 10:buf += xs
           ^^
           found:    scala.collection.immutable.List[Int](o.xs)
-          required: scala.collection.immutable.List[Int](o.xs)
+          required: String
           
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 10:buf += xs
    ^^^^^^^^^
    found:    String
-   required: String
+   required: scala.collection.mutable.ListBuffer[Int]
    
 scala> buf ++= xs
 res1: scala.collection.mutable.ListBuffer[Int] = ListBuffer(1, 2, 3)

From 18d63fe71ebc80bc8e111dbb20b6b0ea1f3700af Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Wed, 28 Sep 2016 10:39:12 +0200
Subject: [PATCH 40/53] Get rid of `kind` in `MessageContainer`

---
 .../tools/dotc/interfaces/Diagnostic.java     |  3 --
 .../tools/dotc/printing/Formatting.scala      |  5 ++-
 .../dotc/reporting/ConsoleReporter.scala      | 33 ++++++++++++-------
 .../dotc/reporting/diagnostic/Message.scala   | 18 ++++------
 .../diagnostic/MessageContainer.scala         |  1 -
 .../dotc/reporting/diagnostic/messages.scala  | 24 +++++---------
 6 files changed, 40 insertions(+), 44 deletions(-)

diff --git a/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java b/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
index e62c1193e921..f94b08e9bf37 100644
--- a/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
+++ b/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
@@ -14,9 +14,6 @@ public interface Diagnostic {
   public static final int WARNING = 1;
   public static final int INFO = 0;
 
-  /** @return The kind of message being reported */
-  String kind();
-
   /** @return The message to report */
   String message();
 
diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index ae3819513577..95ac036470f1 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -75,7 +75,7 @@ object Formatting {
 
   class SyntaxFormatter(sc: StringContext) extends StringFormatter(sc) {
     override protected def showArg(arg: Any)(implicit ctx: Context): String = {
-      arg match {
+      if (ctx.settings.color.value != "never") arg match {
         case arg: Showable =>
           val highlighted =
             SyntaxHighlighting(wrapNonSensical(arg, super.showArg(arg)))
@@ -84,8 +84,11 @@ object Formatting {
           hl.show
         case hb: HighlightBuffer =>
           hb.toString
+        case str: String =>
+          new String(SyntaxHighlighting(str).toArray)
         case _ => super.showArg(arg)
       }
+      else super.showArg(arg)
     }
   }
 
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 261357924af5..e4c24643b9cf 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -14,9 +14,8 @@ import diagnostic.{ Message, MessageContainer }
 import diagnostic.messages._
 
 /**
- * This class implements a more Fancy version (with colors!) of the regular
- * `ConsoleReporter`
- */
+  * This class implements a Reporter that displays messages on a text console
+  */
 class ConsoleReporter(
   reader: BufferedReader = Console.in,
   writer: PrintWriter = new PrintWriter(Console.err, true)
@@ -66,18 +65,22 @@ class ConsoleReporter(
       .mkString(sys.props("line.separator"))
   }
 
-  def posStr(pos: SourcePosition, kind: String, errorId: String)(implicit ctx: Context) =
+  def posStr(pos: SourcePosition, diagnosticLevel: String, message: Message)(implicit ctx: Context) =
     if (pos.exists) Blue({
       val file = pos.source.file.toString
-      val errId = if (errorId != "") s"[$errorId] " else ""
+      val errId = if (message.errorId != "") s"[${message.errorId}] " else ""
+      val kind =
+        if (message.kind == "") diagnosticLevel
+        else s"${message.kind} $diagnosticLevel"
       val prefix = s"-- ${errId}${kind}: $file "
+
       prefix +
       ("-" * math.max(ctx.settings.pageWidth.value - stripColor(prefix).length, 0))
     }).show else ""
 
   /** Prints the message with the given position indication. */
-  def printMessageAndPos(msg: Message, pos: SourcePosition, kind: String)(implicit ctx: Context): Unit = {
-    printMessage(posStr(pos, kind, msg.errorId))
+  def printMessageAndPos(msg: Message, pos: SourcePosition, diagnosticLevel: String)(implicit ctx: Context): Unit = {
+    printMessage(posStr(pos, diagnosticLevel, msg))
     if (pos.exists) {
       val (src, offset) = sourceLine(pos)
       val marker = columnMarker(pos, offset)
@@ -97,15 +100,21 @@ class ConsoleReporter(
   override def doReport(m: MessageContainer)(implicit ctx: Context): Unit = {
     m match {
       case m: Error =>
-        printMessageAndPos(m.contained, m.pos, m.kind)
+        printMessageAndPos(m.contained, m.pos, "Error")
         if (ctx.settings.prompt.value) displayPrompt()
       case m: ConditionalWarning if !m.enablingOption.value =>
+      case m: FeatureWarning =>
+        printMessageAndPos(m.contained, m.pos, "Feature Warning")
+      case m: DeprecationWarning =>
+        printMessageAndPos(m.contained, m.pos, "Deprecation Warning")
+      case m: UncheckedWarning =>
+        printMessageAndPos(m.contained, m.pos, "Unchecked Warning")
       case m: MigrationWarning =>
-        printMessageAndPos(m.contained, m.pos, m.kind)
+        printMessageAndPos(m.contained, m.pos, "Migration Warning")
       case m: Warning =>
-        printMessageAndPos(m.contained, m.pos, m.kind)
-      case _ =>
-        printMessageAndPos(m.contained, m.pos, m.kind)
+        printMessageAndPos(m.contained, m.pos, "Warning")
+      case m: Info =>
+        printMessageAndPos(m.contained, m.pos, "Info")
     }
 
     if (ctx.shouldExplain(m)) printExplanation(m.contained)
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index 443dc4de87af..125ac2e1c67f 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -18,10 +18,6 @@ abstract class Message(val errorId: String) { self =>
   def kind: String
   def explanation: String
 
-  def container(c: String) =
-    if (kind == "") c
-    else s"$kind $c"
-
   def mapMsg(f: String => String) = new Message(errorId) {
     val msg = f(self.msg)
     val kind = self.kind
@@ -29,25 +25,25 @@ abstract class Message(val errorId: String) { self =>
   }
 
   def error(pos: SourcePosition) =
-    new Error(self, pos, container("Error"), explanation)
+    new Error(self, pos, explanation)
 
   def warning(pos: SourcePosition) =
-    new Warning(self, pos, container("Warning"), explanation)
+    new Warning(self, pos, explanation)
 
   def info(pos: SourcePosition) =
-    new Info(self, pos, container("Info"), explanation)
+    new Info(self, pos, explanation)
 
   def featureWarning(pos: SourcePosition) =
-    new FeatureWarning(self, pos, container("Feature Warning"), explanation)
+    new FeatureWarning(self, pos, explanation)
 
   def uncheckedWarning(pos: SourcePosition) =
-    new UncheckedWarning(self, pos, container("Unchecked Warning"), explanation)
+    new UncheckedWarning(self, pos, explanation)
 
   def deprecationWarning(pos: SourcePosition) =
-    new DeprecationWarning(self, pos, container("Deprecation Warning"), explanation)
+    new DeprecationWarning(self, pos, explanation)
 
   def migrationWarning(pos: SourcePosition) =
-    new MigrationWarning(self, pos, container("Migration Warning"), explanation)
+    new MigrationWarning(self, pos, explanation)
 }
 
 class NoExplanation(val msg: String) extends Message("") {
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
index a1a99f17d3a6..f49bebd94f07 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
@@ -27,7 +27,6 @@ class MessageContainer(
   msgFn: => Message,
   val pos: SourcePosition,
   val level: Int,
-  val kind: String,
   val explanation: String
 ) extends Exception with interfaces.Diagnostic {
   import MessageContainer._
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 034e14267635..26c5622facb8 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -18,66 +18,58 @@ object messages {
   class Error(
     msgFn: => Message,
     pos: SourcePosition,
-    kind: String,
     explanation: String = ""
-  ) extends MessageContainer(msgFn, pos, ERROR, kind, explanation)
+  ) extends MessageContainer(msgFn, pos, ERROR, explanation)
 
   class Warning(
     msgFn: => Message,
     pos: SourcePosition,
-    kind: String,
     explanation: String = ""
-  ) extends MessageContainer(msgFn, pos, WARNING, kind, explanation)
+  ) extends MessageContainer(msgFn, pos, WARNING, explanation)
 
   class Info(
     msgFn: => Message,
     pos: SourcePosition,
-    kind: String,
     explanation: String = ""
-  ) extends MessageContainer(msgFn, pos, INFO, kind, explanation)
+  ) extends MessageContainer(msgFn, pos, INFO, explanation)
 
   abstract class ConditionalWarning(
     msgFn: => Message,
     pos: SourcePosition,
-    kind: String,
     explanation: String = ""
-  ) extends Warning(msgFn, pos, kind, explanation) {
+  ) extends Warning(msgFn, pos, explanation) {
     def enablingOption(implicit ctx: Context): Setting[Boolean]
   }
 
   class FeatureWarning(
     msgFn: => Message,
     pos: SourcePosition,
-    kind: String = "Feature Warning",
     explanation: String = ""
-  ) extends ConditionalWarning(msgFn, pos, kind, explanation) {
+  ) extends ConditionalWarning(msgFn, pos, explanation) {
     def enablingOption(implicit ctx: Context) = ctx.settings.feature
   }
 
   class UncheckedWarning(
     msgFn: => Message,
     pos: SourcePosition,
-    kind: String = "Unchecked Warning",
     explanation: String = ""
-  ) extends ConditionalWarning(msgFn, pos, kind, explanation) {
+  ) extends ConditionalWarning(msgFn, pos, explanation) {
     def enablingOption(implicit ctx: Context) = ctx.settings.unchecked
   }
 
   class DeprecationWarning(
     msgFn: => Message,
     pos: SourcePosition,
-    kind: String = "Deprecation Warning",
     explanation: String = ""
-  ) extends ConditionalWarning(msgFn, pos, kind, explanation) {
+  ) extends ConditionalWarning(msgFn, pos, explanation) {
     def enablingOption(implicit ctx: Context) = ctx.settings.deprecation
   }
 
   class MigrationWarning(
     msgFn: => Message,
     pos: SourcePosition,
-    kind: String = "Migration Warning",
     explanation: String = ""
-  ) extends ConditionalWarning(msgFn, pos, kind, explanation) {
+  ) extends ConditionalWarning(msgFn, pos, explanation) {
     def enablingOption(implicit ctx: Context) = ctx.settings.migration
   }
 

From f7b8980fad5adb20e9a420a16f5b3416927dccbc Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Wed, 28 Sep 2016 11:41:36 +0200
Subject: [PATCH 41/53] Improve documentation for message framework

---
 src/dotty/tools/dotc/ast/Trees.scala          |  4 +-
 .../dotc/reporting/diagnostic/Message.scala   | 40 ++++++++++++++++++-
 .../dotc/reporting/diagnostic/messages.scala  | 14 +++----
 3 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/src/dotty/tools/dotc/ast/Trees.scala b/src/dotty/tools/dotc/ast/Trees.scala
index 70701ecd773f..0f9198b795dd 100644
--- a/src/dotty/tools/dotc/ast/Trees.scala
+++ b/src/dotty/tools/dotc/ast/Trees.scala
@@ -3,8 +3,8 @@ package dotc
 package ast
 
 import core._
-import Types._, Names._, Flags._, util.Positions._, Contexts._, Constants._, SymDenotations._, Symbols._
-import Denotations._, StdNames._, Comments._
+import Types._, Names._, Flags._, util.Positions._, Contexts._, Constants._
+import SymDenotations._, Symbols._, Denotations._, StdNames._, Comments._
 import annotation.tailrec
 import language.higherKinds
 import collection.IndexedSeqOptimized
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index 125ac2e1c67f..e365851bee38 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -3,10 +3,14 @@ package dotc
 package reporting
 package diagnostic
 
-import util.{SourcePosition, NoSourcePosition}
+import util.SourcePosition
 import core.Contexts.Context
 
 object Message {
+  /** This implicit conversion provides a fallback for error messages that have
+    * not yet been ported to the new scheme. Comment out this `implicit def` to
+    * see where old errors still exist
+    */
   implicit def toNoExplanation(str: String): Message =
     new NoExplanation(str)
 }
@@ -14,43 +18,77 @@ object Message {
 abstract class Message(val errorId: String) { self =>
   import messages._
 
+  /** The `msg` contains the diagnostic message e.g:
+    *
+    * > expected: String
+    * > found:    Int
+    *
+    * This message wil be placed underneath the position given by the enclosing
+    * `MessageContainer`
+    */
   def msg: String
+
+  /** The kind of the error message is something like "Syntax" or "Type
+    * Mismatch"
+    */
   def kind: String
+
+  /** The explanation should provide a detailed description of why the error
+    * occurred and use examples from the user's own code to illustrate how to
+    * avoid these errors.
+    */
   def explanation: String
 
+  /** It is possible to map `msg` to add details, this is at the loss of
+    * precision since the type of the resulting `Message` won't be original
+    * extending class
+    *
+    * @return a `Message` with the mapped message
+    */
   def mapMsg(f: String => String) = new Message(errorId) {
     val msg = f(self.msg)
     val kind = self.kind
     val explanation = self.explanation
   }
 
+  /** Enclose this message in an `Error` container */
   def error(pos: SourcePosition) =
     new Error(self, pos, explanation)
 
+  /** Enclose this message in an `Warning` container */
   def warning(pos: SourcePosition) =
     new Warning(self, pos, explanation)
 
+  /** Enclose this message in an `Info` container */
   def info(pos: SourcePosition) =
     new Info(self, pos, explanation)
 
+  /** Enclose this message in an `FeatureWarning` container */
   def featureWarning(pos: SourcePosition) =
     new FeatureWarning(self, pos, explanation)
 
+  /** Enclose this message in an `UncheckedWarning` container */
   def uncheckedWarning(pos: SourcePosition) =
     new UncheckedWarning(self, pos, explanation)
 
+  /** Enclose this message in an `DeprecationWarning` container */
   def deprecationWarning(pos: SourcePosition) =
     new DeprecationWarning(self, pos, explanation)
 
+  /** Enclose this message in an `MigrationWarning` container */
   def migrationWarning(pos: SourcePosition) =
     new MigrationWarning(self, pos, explanation)
 }
 
+/** The fallback `Message` containing no explanation and having no `kind` */
 class NoExplanation(val msg: String) extends Message("") {
   val explanation = ""
   val kind = ""
 }
 
+/** The extractor for `NoExplanation` can be used to check whether any error
+  * lacks an explanation
+  */
 object NoExplanation {
   def unapply(m: Message): Option[Message] =
     if (m.explanation == "") Some(m)
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 26c5622facb8..11c6b43d92b3 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -14,7 +14,7 @@ import printing.Formatting
 
 object messages {
 
-  /** Message container to be consumed by the reporter ---------------------- */
+  // `MessageContainer`s to be consumed by `Reporter` ---------------------- //
   class Error(
     msgFn: => Message,
     pos: SourcePosition,
@@ -73,22 +73,22 @@ object messages {
     def enablingOption(implicit ctx: Context) = ctx.settings.migration
   }
 
-  /**  Messages ----------------------------------------------------------------
-    *
+  /**  Messages
+    *  ========
     *  The role of messages is to provide the necessary details for a simple to
     *  understand diagnostic event. Each message can be turned into a message
     *  container (one of the above) by calling the appropriate method on them.
     *  For instance:
     *
     *  ```scala
-    *  EmptyCatchBlock(tree).error   // res: Error
-    *  EmptyCatchBlock(tree).warning // res: Warning
+    *  EmptyCatchBlock(tree).error(pos)   // res: Error
+    *  EmptyCatchBlock(tree).warning(pos) // res: Warning
     *  ```
     */
   import dotc.ast.Trees._
   import dotc.ast.untpd
 
-  /** Syntax Errors --------------------------------------------------------- */
+  // Syntax Errors ---------------------------------------------------------- //
   abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree, errNo: String)(implicit ctx: Context)
   extends Message(errNo) {
     val explanation = {
@@ -166,7 +166,7 @@ object messages {
     }
   }
 
-  /** Type Errors ----------------------------------------------------------- */
+  // Type Errors ------------------------------------------------------------ //
   case class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context)
   extends Message("E004") {
     val kind = "Naming"

From e42bb303231b9c91f679c410d51455ba91df024d Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Wed, 28 Sep 2016 13:03:04 +0200
Subject: [PATCH 42/53] Change Message#errorId to type Int

---
 .../tools/dotc/reporting/ConsoleReporter.scala     |  7 +++++--
 .../tools/dotc/reporting/diagnostic/Message.scala  |  6 ++++--
 .../tools/dotc/reporting/diagnostic/messages.scala | 14 +++++++-------
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index e4c24643b9cf..8ded4035ce66 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -10,7 +10,7 @@ import java.io.{ BufferedReader, IOException, PrintWriter }
 import scala.reflect.internal.util._
 import printing.SyntaxHighlighting._
 import printing.Highlighting._
-import diagnostic.{ Message, MessageContainer }
+import diagnostic.{ Message, MessageContainer, NoExplanation }
 import diagnostic.messages._
 
 /**
@@ -68,7 +68,10 @@ class ConsoleReporter(
   def posStr(pos: SourcePosition, diagnosticLevel: String, message: Message)(implicit ctx: Context) =
     if (pos.exists) Blue({
       val file = pos.source.file.toString
-      val errId = if (message.errorId != "") s"[${message.errorId}] " else ""
+      val errId =
+        if (message.errorId != NoExplanation.ID)
+          s"[E${"0" * (3 - message.errorId.toString.length) + message.errorId}] "
+        else ""
       val kind =
         if (message.kind == "") diagnosticLevel
         else s"${message.kind} $diagnosticLevel"
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index e365851bee38..f19191f4fcad 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -15,7 +15,7 @@ object Message {
     new NoExplanation(str)
 }
 
-abstract class Message(val errorId: String) { self =>
+abstract class Message(val errorId: Int) { self =>
   import messages._
 
   /** The `msg` contains the diagnostic message e.g:
@@ -81,7 +81,7 @@ abstract class Message(val errorId: String) { self =>
 }
 
 /** The fallback `Message` containing no explanation and having no `kind` */
-class NoExplanation(val msg: String) extends Message("") {
+class NoExplanation(val msg: String) extends Message(NoExplanation.ID) {
   val explanation = ""
   val kind = ""
 }
@@ -90,6 +90,8 @@ class NoExplanation(val msg: String) extends Message("") {
   * lacks an explanation
   */
 object NoExplanation {
+  final val ID = -1
+
   def unapply(m: Message): Option[Message] =
     if (m.explanation == "") Some(m)
     else None
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 11c6b43d92b3..4553a2d221cc 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -89,7 +89,7 @@ object messages {
   import dotc.ast.untpd
 
   // Syntax Errors ---------------------------------------------------------- //
-  abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree, errNo: String)(implicit ctx: Context)
+  abstract class EmptyCatchOrFinallyBlock(tryBody: untpd.Tree, errNo: Int)(implicit ctx: Context)
   extends Message(errNo) {
     val explanation = {
       val tryString = tryBody match {
@@ -121,7 +121,7 @@ object messages {
   }
 
   case class EmptyCatchBlock(tryBody: untpd.Tree)(implicit ctx: Context)
-  extends EmptyCatchOrFinallyBlock(tryBody, "E001") {
+  extends EmptyCatchOrFinallyBlock(tryBody, 1) {
     val kind = "Syntax"
     val msg =
       hl"""|The ${"catch"} block does not contain a valid expression, try
@@ -129,7 +129,7 @@ object messages {
   }
 
   case class EmptyCatchAndFinallyBlock(tryBody: untpd.Tree)(implicit ctx: Context)
-  extends EmptyCatchOrFinallyBlock(tryBody, "E002") {
+  extends EmptyCatchOrFinallyBlock(tryBody, 2) {
     val kind = "Syntax"
     val msg =
       hl"""|A ${"try"} without ${"catch"} or ${"finally"} is equivalent to putting
@@ -137,7 +137,7 @@ object messages {
   }
 
   case class DeprecatedWithOperator()(implicit ctx: Context)
-  extends Message("E003") {
+  extends Message(3) {
     val kind = "Syntax"
     val msg =
       hl"""${"with"} as a type operator has been deprecated; use `&' instead"""
@@ -168,7 +168,7 @@ object messages {
 
   // Type Errors ------------------------------------------------------------ //
   case class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context)
-  extends Message("E004") {
+  extends Message(4) {
     val kind = "Naming"
     val msg = em"duplicate pattern variable: `${bind.name}`"
 
@@ -195,7 +195,7 @@ object messages {
   }
 
   case class MissingIdent(tree: untpd.Ident, treeKind: String, name: String)(implicit ctx: Context)
-  extends Message("E005") {
+  extends Message(5) {
     val kind = "Missing Identifier"
     val msg = em"not found: $treeKind$name"
 
@@ -206,7 +206,7 @@ object messages {
   }
 
   case class TypeMismatch(found: Type, expected: Type, whyNoMatch: String = "", implicitFailure: String = "")(implicit ctx: Context)
-  extends Message("E006") {
+  extends Message(6) {
     val kind = "Type Mismatch"
     private val (where, printCtx) = Formatting.disambiguateTypes(found, expected)
     private val (fnd, exp) = Formatting.typeDiff(found, expected)(printCtx)

From a0026a09d76c09266c368c7a07a0cc2c5994367e Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 29 Sep 2016 15:27:18 +0200
Subject: [PATCH 43/53] Make reporter hint about existing explanations

---
 src/dotty/tools/dotc/reporting/ConsoleReporter.scala | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 8ded4035ce66..45933d9548a3 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -120,7 +120,10 @@ class ConsoleReporter(
         printMessageAndPos(m.contained, m.pos, "Info")
     }
 
-    if (ctx.shouldExplain(m)) printExplanation(m.contained)
+    if (ctx.shouldExplain(m))
+      printExplanation(m.contained)
+    else if (m.contained.explanation.nonEmpty)
+      printMessage("\nlonger explanation available when compiling with `-explain`")
   }
 
   def displayPrompt(): Unit = {

From 0781b31fa4e3d22cb6a51882b8d632ea9a16ed6f Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 29 Sep 2016 15:45:46 +0200
Subject: [PATCH 44/53] Handle multiline messages in ConsoleReporter

---
 .../dotc/reporting/ConsoleReporter.scala      | 46 ++++++----
 src/dotty/tools/dotc/util/SourceFile.scala    |  2 +-
 .../tools/dotc/util/SourcePosition.scala      | 11 +++
 tests/repl/errmsgs.check                      | 90 +++++++++----------
 tests/repl/imports.check                      | 16 ++--
 5 files changed, 90 insertions(+), 75 deletions(-)

diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 45933d9548a3..d96ff48a4b56 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -32,24 +32,35 @@ class ConsoleReporter(
   def stripColor(str: String): String =
     str.replaceAll("\u001B\\[[;\\d]*m", "")
 
-  def sourceLine(pos: SourcePosition)(implicit ctx: Context): (String, Int) = {
-    val lineNum = s"${pos.line}:"
-    (lineNum + hl"${pos.lineContent.stripLineEnd}", lineNum.length)
-  }
+  def sourceLines(pos: SourcePosition)(implicit ctx: Context): (List[String], Int) = {
+    var maxLen = Int.MinValue
+    val lines = pos.lines
+      .map { lineNbr =>
+        val prefix = s"${lineNbr + 1} |"
+        maxLen = math.max(maxLen, prefix.length)
+        (prefix, pos.lineContent(lineNbr).stripLineEnd)
+      }
+      .map { case (prefix, line) =>
+        val lnum = Red(" " * math.max(0, maxLen - prefix.length) + prefix)
+        hl"$lnum$line"
+      }
 
-  def columnMarker(pos: SourcePosition, offset: Int)(implicit ctx: Context) =
-    if (pos.startLine == pos.endLine) {
-      val whitespace = " " * (pos.startColumn + offset)
-      val carets =
-        Red("^" * math.max(1, pos.endColumn - pos.startColumn))
+    (lines, maxLen)
+  }
 
-      whitespace + carets.show
-    } else {
-      Red(" " * (pos.column + offset) + "^").show
+  def columnMarker(pos: SourcePosition, offset: Int)(implicit ctx: Context) = {
+    val prefix = " " * (offset - 1)
+    val whitespace = " " * pos.startColumn
+    val carets = Red {
+      if (pos.startLine == pos.endLine)
+        "^" * math.max(1, pos.endColumn - pos.startColumn)
+      else "^"
     }
 
+    s"$prefix|$whitespace${carets.show}"
+  }
+
   def errorMsg(pos: SourcePosition, msg: String, offset: Int)(implicit ctx: Context) = {
-    var hasLongLines = false
     val leastWhitespace = msg.lines.foldLeft(Int.MaxValue) { (minPad, line) =>
       val lineLength = stripColor(line).length
       val padding =
@@ -59,9 +70,8 @@ class ConsoleReporter(
       else minPad
     }
 
-    msg
-      .lines
-      .map { line => " " * leastWhitespace + line }
+    msg.lines
+      .map { line => " " * (offset - 1) + "|" + (" " * (leastWhitespace - offset)) + line }
       .mkString(sys.props("line.separator"))
   }
 
@@ -85,11 +95,11 @@ class ConsoleReporter(
   def printMessageAndPos(msg: Message, pos: SourcePosition, diagnosticLevel: String)(implicit ctx: Context): Unit = {
     printMessage(posStr(pos, diagnosticLevel, msg))
     if (pos.exists) {
-      val (src, offset) = sourceLine(pos)
+      val (srcLines, offset) = sourceLines(pos)
       val marker = columnMarker(pos, offset)
       val err = errorMsg(pos, msg.msg, offset)
 
-      printMessage(List(src, marker, err).mkString("\n"))
+      printMessage((srcLines ::: marker :: err :: Nil).mkString("\n"))
     } else printMessage(msg.msg)
   }
 
diff --git a/src/dotty/tools/dotc/util/SourceFile.scala b/src/dotty/tools/dotc/util/SourceFile.scala
index 8bd0ecfd6706..1d4c9c2ab6f2 100644
--- a/src/dotty/tools/dotc/util/SourceFile.scala
+++ b/src/dotty/tools/dotc/util/SourceFile.scala
@@ -97,7 +97,7 @@ case class SourceFile(file: AbstractFile, content: Array[Char]) extends interfac
   private lazy val lineIndices: Array[Int] = calculateLineIndices(content)
 
   /** Map line to offset of first character in line */
-  def lineToOffset(index : Int): Int = lineIndices(index)
+  def lineToOffset(index: Int): Int = lineIndices(index)
 
   /** A cache to speed up offsetToLine searches to similar lines */
   private var lastLine = 0
diff --git a/src/dotty/tools/dotc/util/SourcePosition.scala b/src/dotty/tools/dotc/util/SourcePosition.scala
index 68a9b64036d8..d0f9cb887e6d 100644
--- a/src/dotty/tools/dotc/util/SourcePosition.scala
+++ b/src/dotty/tools/dotc/util/SourcePosition.scala
@@ -14,6 +14,17 @@ extends interfaces.SourcePosition {
   def point: Int = pos.point
   /** The line of the position, starting at 0 */
   def line: Int = source.offsetToLine(point)
+
+  /** The lines of the position */
+  def lines: List[Int] =
+    List.range(source.offsetToLine(start), source.offsetToLine(end)) match {
+      case Nil => line :: Nil
+      case xs => xs
+    }
+
+  def lineContent(lineNumber: Int): String =
+    source.lineContent(source.lineToOffset(lineNumber))
+
   /** The column of the position, starting at 0 */
   def column: Int = source.column(point)
 
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index b8cff5ba2df6..2a65fd9491d8 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -2,46 +2,46 @@ scala> class Inv[T](x: T)
 defined class Inv
 scala> val x: List[String] = List(1)
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-3:val x: List[String] = List(1)
-                             ^
-                             found:    Int(1)
-                             required: String
-                             
+4 |val x: List[String] = List(1)
+  |                           ^
+  |                           found:    Int(1)
+  |                           required: String
+  |                           
 scala> val y: List[List[String]] = List(List(1))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-3:val y: List[List[String]] = List(List(1))
-                                        ^
-                                        found:    Int(1)
-                                        required: String
-                                        
+4 |val y: List[List[String]] = List(List(1))
+  |                                      ^
+  |                                      found:    Int(1)
+  |                                      required: String
+  |                                      
 scala> val z: (List[String], List[Int]) = (List(1), List("a"))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-3:val z: (List[String], List[Int]) = (List(1), List("a"))
-                                           ^
-                                           found:    Int(1)
-                                           required: String
-                                           
+4 |val z: (List[String], List[Int]) = (List(1), List("a"))
+  |                                         ^
+  |                                         found:    Int(1)
+  |                                         required: String
+  |                                         
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-3:val z: (List[String], List[Int]) = (List(1), List("a"))
-                                                    ^^^
-                                                    found:    String("a")
-                                                    required: Int
-                                                    
+4 |val z: (List[String], List[Int]) = (List(1), List("a"))
+  |                                                  ^^^
+  |                                                  found:    String("a")
+  |                                                  required: Int
+  |                                                  
 scala> val a: Inv[String] = new Inv(new Inv(1))
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-4:val a: Inv[String] = new Inv(new Inv(1))
-                                   ^^^^^
-                                   found:    Inv[T]
-                                   required: String
-                                   
-                                   where:    T is a type variable with constraint >: Int(1)
+5 |val a: Inv[String] = new Inv(new Inv(1))
+  |                                 ^^^^^
+  |                                 found:    Inv[T]
+  |                                 required: String
+  |                                 
+  |                                 where:    T is a type variable with constraint >: Int(1)
 scala> val b: Inv[String] = new Inv(1)
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-4:val b: Inv[String] = new Inv(1)
-                               ^
-                               found:    Int(1)
-                               required: String
-                               
+5 |val b: Inv[String] = new Inv(1)
+  |                             ^
+  |                             found:    Int(1)
+  |                             required: String
+  |                             
 scala> abstract class C {
            type T
            val x: T
@@ -58,19 +58,19 @@ scala> abstract class C {
            }
          }
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-8:      var y: T = x
-                   ^
-                   found:    C.this.T(C.this.x)
-                   required: T'
-                   
-                   where:    T  is a type in class C
-                             T' is a type in the initalizer of value s which is an alias of String
+9 |      var y: T = x
+  |                 ^
+  |                 found:    C.this.T(C.this.x)
+  |                 required: T'
+  |                 
+  |                 where:    T  is a type in class C
+  |                           T' is a type in the initalizer of value s which is an alias of String
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-12:          val z: T = y
-                        ^
-                        found:    T(y)
-                        required: T'
-                        
-                        where:    T  is a type in the initalizer of value s which is an alias of String
-                                  T' is a type in method f which is an alias of Int
+13 |          val z: T = y
+   |                     ^
+   |                     found:    T(y)
+   |                     required: T'
+   |                     
+   |                     where:    T  is a type in the initalizer of value s which is an alias of String
+   |                               T' is a type in method f which is an alias of Int
 scala> :quit
diff --git a/tests/repl/imports.check b/tests/repl/imports.check
index 2e8d5dcf967f..9743d2b9430e 100644
--- a/tests/repl/imports.check
+++ b/tests/repl/imports.check
@@ -8,17 +8,11 @@ scala> import o._
 import o._
 scala> buf += xs
 -- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-10:buf += xs
-          ^^
-          found:    scala.collection.immutable.List[Int](o.xs)
-          required: String
-          
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
-10:buf += xs
-   ^^^^^^^^^
-   found:    String
-   required: scala.collection.mutable.ListBuffer[Int]
-   
+11 |buf += xs
+   |       ^^
+   |       found:    scala.collection.immutable.List[Int](o.xs)
+   |       required: String
+   |       
 scala> buf ++= xs
 res1: scala.collection.mutable.ListBuffer[Int] = ListBuffer(1, 2, 3)
 scala> :quit

From f23ff3abba8663a0e7f64f79b556efd36cc86a83 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Thu, 29 Sep 2016 17:10:45 +0200
Subject: [PATCH 45/53] Improve positions for MemberDefs using `namePos`

---
 src/dotty/tools/dotc/ast/Desugar.scala        |  7 +++++--
 src/dotty/tools/dotc/parsing/Parsers.scala    | 20 ++++++++++++++++---
 .../tools/dotc/printing/Formatting.scala      | 10 ++++------
 .../dotc/reporting/ConsoleReporter.scala      |  1 +
 .../reporting/UniqueMessagePositions.scala    | 16 ++++++++-------
 .../dotc/reporting/diagnostic/messages.scala  | 19 +++++++++++++++---
 src/dotty/tools/dotc/transform/TailRec.scala  | 13 ++++++++----
 src/dotty/tools/dotc/typer/Checking.scala     |  8 ++++----
 src/dotty/tools/dotc/typer/Typer.scala        |  2 +-
 tests/neg/applydynamic_sip.scala              |  6 +++---
 tests/neg/assignments.scala                   |  2 +-
 tests/neg/dynamicApplyDynamicTest3.scala      |  2 +-
 tests/neg/i1424.scala                         |  2 +-
 tests/neg/tailcall/t6574.scala                |  2 +-
 tests/repl/errmsgs.check                      | 16 +++++++--------
 tests/repl/imports.check                      |  2 +-
 16 files changed, 82 insertions(+), 46 deletions(-)

diff --git a/src/dotty/tools/dotc/ast/Desugar.scala b/src/dotty/tools/dotc/ast/Desugar.scala
index ecb6a3212f70..af34164dce9d 100644
--- a/src/dotty/tools/dotc/ast/Desugar.scala
+++ b/src/dotty/tools/dotc/ast/Desugar.scala
@@ -9,6 +9,7 @@ import Decorators._
 import language.higherKinds
 import collection.mutable.ListBuffer
 import util.Property
+import reporting.diagnostic.messages._
 
 object desugar {
   import untpd._
@@ -71,7 +72,9 @@ object desugar {
             val defctx = ctx.outersIterator.dropWhile(_.scope eq ctx.scope).next
             var local = defctx.denotNamed(tp.name).suchThat(_ is ParamOrAccessor).symbol
             if (local.exists) (defctx.owner.thisType select local).dealias
-            else throw new Error(s"no matching symbol for ${tp.symbol.showLocated} in ${defctx.owner} / ${defctx.effectiveScope}")
+            else throw new java.lang.Error(
+              s"no matching symbol for ${tp.symbol.showLocated} in ${defctx.owner} / ${defctx.effectiveScope}"
+            )
           case _ =>
             mapOver(tp)
         }
@@ -281,7 +284,7 @@ object desugar {
     val constrVparamss =
       if (constr1.vparamss.isEmpty) { // ensure parameter list is non-empty
         if (isCaseClass)
-          ctx.error("case class needs to have at least one parameter list", cdef.pos)
+          ctx.error(CaseClassMissingParamList(cdef), cdef.namePos)
         ListOfNil
       }
       else constr1.vparamss.nestedMap(toDefParam)
diff --git a/src/dotty/tools/dotc/parsing/Parsers.scala b/src/dotty/tools/dotc/parsing/Parsers.scala
index 620cc1273272..6d40107a8cc0 100644
--- a/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -215,6 +215,9 @@ object Parsers {
       }
     }
 
+    def warning(msg: Message, sourcePos: SourcePosition) =
+      ctx.warning(msg, sourcePos)
+
     def warning(msg: Message, offset: Int = in.offset) =
       ctx.warning(msg, source atPos Position(offset))
 
@@ -1006,6 +1009,7 @@ object Parsers {
           DoWhile(body, cond)
         }
       case TRY =>
+        val tryOffset = in.offset
         atPos(in.skipToken()) {
           val body = expr()
           val handler =
@@ -1014,16 +1018,26 @@ object Parsers {
               expr()
             } else EmptyTree
 
+          // A block ends before RBRACE, if next token is RBRACE, simply add 1
+          def realEnd(pos: Position) =
+            if (in.token == RBRACE) pos.end + 1
+            else pos.end
+
           handler match {
-            case Block(Nil, EmptyTree) =>
-              syntaxError(new EmptyCatchBlock(body), handler.pos)
+            case Block(Nil, EmptyTree) => syntaxError(
+              new EmptyCatchBlock(body),
+              Position(tryOffset, realEnd(handler.pos))
+            )
             case _ =>
           }
 
           val finalizer =
             if (in.token == FINALLY) { accept(FINALLY); expr() }
             else {
-              if (handler.isEmpty) warning(EmptyCatchAndFinallyBlock(body))
+              if (handler.isEmpty) warning(
+                EmptyCatchAndFinallyBlock(body),
+                source atPos Position(tryOffset, realEnd(body.pos))
+              )
               EmptyTree
             }
           ParsedTry(body, handler, finalizer)
diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index 95ac036470f1..9cbf079142a1 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -74,9 +74,9 @@ object Formatting {
   }
 
   class SyntaxFormatter(sc: StringContext) extends StringFormatter(sc) {
-    override protected def showArg(arg: Any)(implicit ctx: Context): String = {
-      if (ctx.settings.color.value != "never") arg match {
-        case arg: Showable =>
+    override protected def showArg(arg: Any)(implicit ctx: Context): String =
+      arg match {
+        case arg: Showable if ctx.settings.color.value != "never" =>
           val highlighted =
             SyntaxHighlighting(wrapNonSensical(arg, super.showArg(arg)))
           new String(highlighted.toArray)
@@ -84,12 +84,10 @@ object Formatting {
           hl.show
         case hb: HighlightBuffer =>
           hb.toString
-        case str: String =>
+        case str: String if ctx.settings.color.value != "never" =>
           new String(SyntaxHighlighting(str).toArray)
         case _ => super.showArg(arg)
       }
-      else super.showArg(arg)
-    }
   }
 
   private def wrapNonSensical(arg: Any, str: String)(implicit ctx: Context): String = {
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index d96ff48a4b56..6ebd53beaec3 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -108,6 +108,7 @@ class ConsoleReporter(
                       |${Blue("Explanation")}
                       |${Blue("===========")}""".stripMargin)
     printMessage(m.explanation)
+    if (m.explanation.lastOption != Some('\n')) printMessage("")
   }
 
   override def doReport(m: MessageContainer)(implicit ctx: Context): Unit = {
diff --git a/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala b/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
index c5ff8cb6b593..6fd971c2a4c0 100644
--- a/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
+++ b/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
@@ -7,10 +7,8 @@ import util.{SourcePosition, SourceFile}
 import core.Contexts.Context
 import diagnostic.MessageContainer
 
-/**
- * This trait implements `isHidden` so that multiple messages per position
- * are suppressed, unless they are of increasing severity.
- */
+/** This trait implements `isHidden` so that multiple messages per position
+  * are suppressed, unless they are of increasing severity. */
 trait UniqueMessagePositions extends Reporter {
 
   private val positions = new mutable.HashMap[(SourceFile, Int), Int]
@@ -21,10 +19,14 @@ trait UniqueMessagePositions extends Reporter {
   override def isHidden(m: MessageContainer)(implicit ctx: Context): Boolean =
     super.isHidden(m) || {
       m.pos.exists && {
-        positions get (ctx.source, m.pos.point) match {
-          case Some(level) if level >= m.level => true
-          case _ => positions((ctx.source, m.pos.point)) = m.level; false
+        var shouldHide = false
+        for (pos <- m.pos.start to m.pos.end) {
+          positions get (ctx.source, pos) match {
+            case Some(level) if level >= m.level => shouldHide = true
+            case _ => positions((ctx.source, pos)) = m.level
+          }
         }
+        shouldHide
       }
     }
 }
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 4553a2d221cc..14978449a92c 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -166,9 +166,22 @@ object messages {
     }
   }
 
+  case class CaseClassMissingParamList(cdef: untpd.TypeDef)(implicit ctx: Context)
+  extends Message(4) {
+    val kind = "Syntax"
+    val msg =
+      hl"""|A ${"case class"} must have at least one parameter list"""
+
+    val explanation =
+      hl"""|${cdef.name} must have at least one parameter list, if you would rather
+           |have a singleton representation of ${cdef.name}, use a "${"case object"}".
+           |Or, add an explicit `()' as a parameter list to ${cdef.name}.""".stripMargin
+  }
+
+
   // Type Errors ------------------------------------------------------------ //
   case class DuplicateBind(bind: untpd.Bind, tree: untpd.CaseDef)(implicit ctx: Context)
-  extends Message(4) {
+  extends Message(5) {
     val kind = "Naming"
     val msg = em"duplicate pattern variable: `${bind.name}`"
 
@@ -195,7 +208,7 @@ object messages {
   }
 
   case class MissingIdent(tree: untpd.Ident, treeKind: String, name: String)(implicit ctx: Context)
-  extends Message(5) {
+  extends Message(6) {
     val kind = "Missing Identifier"
     val msg = em"not found: $treeKind$name"
 
@@ -206,7 +219,7 @@ object messages {
   }
 
   case class TypeMismatch(found: Type, expected: Type, whyNoMatch: String = "", implicitFailure: String = "")(implicit ctx: Context)
-  extends Message(6) {
+  extends Message(7) {
     val kind = "Type Mismatch"
     private val (where, printCtx) = Formatting.disambiguateTypes(found, expected)
     private val (fnd, exp) = Formatting.typeDiff(found, expected)(printCtx)
diff --git a/src/dotty/tools/dotc/transform/TailRec.scala b/src/dotty/tools/dotc/transform/TailRec.scala
index b345dda61848..065bcb397690 100644
--- a/src/dotty/tools/dotc/transform/TailRec.scala
+++ b/src/dotty/tools/dotc/transform/TailRec.scala
@@ -145,17 +145,22 @@ class TailRec extends MiniPhaseTransform with DenotTransformer with FullParamete
                 })
                 Block(List(labelDef), ref(label).appliedToArgss(vparamss0.map(_.map(x=> ref(x.symbol)))))
             }} else {
-              if (mandatory)
-                ctx.error("TailRec optimisation not applicable, method not tail recursive", dd.pos)
+              if (mandatory) ctx.error(
+                "TailRec optimisation not applicable, method not tail recursive",
+                // FIXME: want to report this error on `dd.namePos`, but
+                // because of extension method getting a weird pos, it is
+                // better to report on symbol so there's no overlap
+                sym.pos
+              )
               dd.rhs
             }
           })
         }
       case d: DefDef if d.symbol.hasAnnotation(defn.TailrecAnnot) || methodsWithInnerAnnots.contains(d.symbol) =>
-        ctx.error("TailRec optimisation not applicable, method is neither private nor final so can be overridden", d.pos)
+        ctx.error("TailRec optimisation not applicable, method is neither private nor final so can be overridden", sym.pos)
         d
       case d if d.symbol.hasAnnotation(defn.TailrecAnnot) || methodsWithInnerAnnots.contains(d.symbol) =>
-        ctx.error("TailRec optimisation not applicable, not a method", d.pos)
+        ctx.error("TailRec optimisation not applicable, not a method", sym.pos)
         d
       case _ => tree
     }
diff --git a/src/dotty/tools/dotc/typer/Checking.scala b/src/dotty/tools/dotc/typer/Checking.scala
index b02b0ad21fc8..7ba66e3d8a61 100644
--- a/src/dotty/tools/dotc/typer/Checking.scala
+++ b/src/dotty/tools/dotc/typer/Checking.scala
@@ -45,7 +45,7 @@ object Checking {
     for ((arg, which, bound) <- ctx.boundsViolations(args, boundss, instantiate))
       ctx.error(
           ex"Type argument ${arg.tpe} does not conform to $which bound $bound ${err.whyNoMatchStr(arg.tpe, bound)}",
-          arg.pos)
+          arg.pos.focus)
   }
 
   /** Check that type arguments `args` conform to corresponding bounds in `poly`
@@ -98,9 +98,9 @@ object Checking {
             checkWildcardHKApply(tycon.tpe.appliedTo(args.map(_.tpe)), tree.pos)
           checkValidIfHKApply(ctx.addMode(Mode.AllowLambdaWildcardApply))
         case Select(qual, name) if name.isTypeName =>
-          checkRealizable(qual.tpe, qual.pos)
+          checkRealizable(qual.tpe, qual.pos.focus)
         case SingletonTypeTree(ref) =>
-          checkRealizable(ref.tpe, ref.pos)
+          checkRealizable(ref.tpe, ref.pos.focus)
         case _ =>
       }
       traverseChildren(tree)
@@ -378,7 +378,7 @@ object Checking {
             if (tp.symbol.is(Private) &&
                 !accessBoundary(sym).isContainedIn(tp.symbol.owner)) {
               errors = (em"non-private $sym refers to private ${tp.symbol}\n in its type signature ${sym.info}",
-                        pos) :: errors
+                        sym.pos) :: errors
               tp
             }
             else mapOver(tp)
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index a4dc2f87138d..bbb20bcf5d5d 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -1259,7 +1259,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
     val impl1 = cpy.Template(impl)(constr1, parents1, self1, body1)
       .withType(dummy.nonMemberTermRef)
     checkVariance(impl1)
-    if (!cls.is(AbstractOrTrait) && !ctx.isAfterTyper) checkRealizableBounds(cls.typeRef, cdef.pos)
+    if (!cls.is(AbstractOrTrait) && !ctx.isAfterTyper) checkRealizableBounds(cls.typeRef, cdef.namePos)
     val cdef1 = assignType(cpy.TypeDef(cdef)(name, impl1, Nil), cls)
     if (ctx.phase.isTyper && cdef1.tpe.derivesFrom(defn.DynamicClass) && !ctx.dynamicsEnabled) {
       val isRequired = parents1.exists(_.tpe.isRef(defn.DynamicClass))
diff --git a/tests/neg/applydynamic_sip.scala b/tests/neg/applydynamic_sip.scala
index 7b131e7ff908..86cff5fc4d57 100644
--- a/tests/neg/applydynamic_sip.scala
+++ b/tests/neg/applydynamic_sip.scala
@@ -18,9 +18,9 @@ object Test extends App {
   }
   val bad1 = new Bad1
   bad1.sel // error
-  bad1.sel(1) // error // error
-  bad1.sel(a = 1) // error // error
-  bad1.sel = 1 // error // error
+  bad1.sel(1) // error
+  bad1.sel(a = 1) // error
+  bad1.sel = 1 // error
 
   class Bad2 extends Dynamic {
     def selectDynamic = 1
diff --git a/tests/neg/assignments.scala b/tests/neg/assignments.scala
index 5be107717510..273419cb50ba 100644
--- a/tests/neg/assignments.scala
+++ b/tests/neg/assignments.scala
@@ -13,7 +13,7 @@ object assignments {
     x = x + 1
     x *= 2
 
-    x_= = 2  // error should give missing arguments + // error reassignment to val
+    x_= = 2  // error should give missing arguments
   }
 
   var c = new C
diff --git a/tests/neg/dynamicApplyDynamicTest3.scala b/tests/neg/dynamicApplyDynamicTest3.scala
index 61d3c96773b1..d68132b02229 100644
--- a/tests/neg/dynamicApplyDynamicTest3.scala
+++ b/tests/neg/dynamicApplyDynamicTest3.scala
@@ -3,5 +3,5 @@ import scala.language.dynamics
 class Foo extends scala.Dynamic
 
 object DynamicTest {
-  new Foo().bazApply _  // error // error
+  new Foo().bazApply _  // error
 }
diff --git a/tests/neg/i1424.scala b/tests/neg/i1424.scala
index 3586260c19a6..8eba3284211b 100644
--- a/tests/neg/i1424.scala
+++ b/tests/neg/i1424.scala
@@ -1,3 +1,3 @@
 class Test {
-  (x: Int) => x // error: not a legal self type clause // error: package x is not a value // error: package x is not a value
+  (x: Int) => x // error: not a legal self type clause // error: not found x
 }
diff --git a/tests/neg/tailcall/t6574.scala b/tests/neg/tailcall/t6574.scala
index d9ba2882ddab..462ef800f435 100644
--- a/tests/neg/tailcall/t6574.scala
+++ b/tests/neg/tailcall/t6574.scala
@@ -4,7 +4,7 @@ class Bad[X, Y](val v: Int) extends AnyVal {
     println("tail")
   }
 
-  @annotation.tailrec final def differentTypeArgs : Unit = { // error
+  @annotation.tailrec final def differentTypeArgs: Unit = { // error
     {(); new Bad[String, Unit](0)}.differentTypeArgs // error
   }
 }
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index 2a65fd9491d8..066d98d0f91d 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -1,34 +1,34 @@
 scala> class Inv[T](x: T)
 defined class Inv
 scala> val x: List[String] = List(1)
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4 |val x: List[String] = List(1)
   |                           ^
   |                           found:    Int(1)
   |                           required: String
   |                           
 scala> val y: List[List[String]] = List(List(1))
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4 |val y: List[List[String]] = List(List(1))
   |                                      ^
   |                                      found:    Int(1)
   |                                      required: String
   |                                      
 scala> val z: (List[String], List[Int]) = (List(1), List("a"))
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4 |val z: (List[String], List[Int]) = (List(1), List("a"))
   |                                         ^
   |                                         found:    Int(1)
   |                                         required: String
   |                                         
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 4 |val z: (List[String], List[Int]) = (List(1), List("a"))
   |                                                  ^^^
   |                                                  found:    String("a")
   |                                                  required: Int
   |                                                  
 scala> val a: Inv[String] = new Inv(new Inv(1))
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 5 |val a: Inv[String] = new Inv(new Inv(1))
   |                                 ^^^^^
   |                                 found:    Inv[T]
@@ -36,7 +36,7 @@ scala> val a: Inv[String] = new Inv(new Inv(1))
   |                                 
   |                                 where:    T is a type variable with constraint >: Int(1)
 scala> val b: Inv[String] = new Inv(1)
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 5 |val b: Inv[String] = new Inv(1)
   |                             ^
   |                             found:    Int(1)
@@ -57,7 +57,7 @@ scala> abstract class C {
              }
            }
          }
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 9 |      var y: T = x
   |                 ^
   |                 found:    C.this.T(C.this.x)
@@ -65,7 +65,7 @@ scala> abstract class C {
   |                 
   |                 where:    T  is a type in class C
   |                           T' is a type in the initalizer of value s which is an alias of String
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 13 |          val z: T = y
    |                     ^
    |                     found:    T(y)
diff --git a/tests/repl/imports.check b/tests/repl/imports.check
index 9743d2b9430e..26b725637481 100644
--- a/tests/repl/imports.check
+++ b/tests/repl/imports.check
@@ -7,7 +7,7 @@ defined module o
 scala> import o._
 import o._
 scala> buf += xs
--- [E006] Type Mismatch Error: <console> -------------------------------------------------------------------------------
+-- [E007] Type Mismatch Error: <console> -------------------------------------------------------------------------------
 11 |buf += xs
    |       ^^
    |       found:    scala.collection.immutable.List[Int](o.xs)

From 41d642947c678efdd392bd01c632ecd53fd26b48 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 3 Oct 2016 10:02:00 +0200
Subject: [PATCH 46/53] Get rid of unnecessary fields in `MessageContainer`

---
 .../tools/dotc/interfaces/Diagnostic.java     |  3 --
 src/dotty/tools/dotc/ast/Trees.scala          |  2 -
 src/dotty/tools/dotc/reporting/Reporter.scala |  2 +-
 .../dotc/reporting/diagnostic/Message.scala   | 14 +++----
 .../diagnostic/MessageContainer.scala         |  5 +--
 .../dotc/reporting/diagnostic/messages.scala  | 40 ++++++++-----------
 6 files changed, 26 insertions(+), 40 deletions(-)

diff --git a/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java b/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
index f94b08e9bf37..c46360afaa3d 100644
--- a/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
+++ b/interfaces/src/main/java/dotty/tools/dotc/interfaces/Diagnostic.java
@@ -17,9 +17,6 @@ public interface Diagnostic {
   /** @return The message to report */
   String message();
 
-  /** @return The explanation behind the message */
-  String explanation();
-
   /** @return Level of the diagnostic, can be either ERROR, WARNING or INFO */
   int level();
 
diff --git a/src/dotty/tools/dotc/ast/Trees.scala b/src/dotty/tools/dotc/ast/Trees.scala
index 0f9198b795dd..ed3690795763 100644
--- a/src/dotty/tools/dotc/ast/Trees.scala
+++ b/src/dotty/tools/dotc/ast/Trees.scala
@@ -308,8 +308,6 @@ object Trees {
         if (rawMods.is(Synthetic)) Position(pos.point, pos.point)
         else Position(pos.point, pos.point + name.length, pos.point)
       else pos
-
-
   }
 
   /** A ValDef or DefDef tree */
diff --git a/src/dotty/tools/dotc/reporting/Reporter.scala b/src/dotty/tools/dotc/reporting/Reporter.scala
index b969fa8787cd..b38334412cc7 100644
--- a/src/dotty/tools/dotc/reporting/Reporter.scala
+++ b/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -35,7 +35,7 @@ trait Reporting { this: Context =>
     if (this.settings.verbose.value) this.echo(msg, pos)
 
   def echo(msg: => String, pos: SourcePosition = NoSourcePosition): Unit =
-    reporter.report(new Info(msg, pos, "Info"))
+    reporter.report(new Info(msg, pos))
 
   def deprecationWarning(msg: => Message, pos: SourcePosition = NoSourcePosition): Unit =
     reporter.report(msg.deprecationWarning(pos))
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index f19191f4fcad..bdc899ea8b42 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -53,31 +53,31 @@ abstract class Message(val errorId: Int) { self =>
 
   /** Enclose this message in an `Error` container */
   def error(pos: SourcePosition) =
-    new Error(self, pos, explanation)
+    new Error(self, pos)
 
   /** Enclose this message in an `Warning` container */
   def warning(pos: SourcePosition) =
-    new Warning(self, pos, explanation)
+    new Warning(self, pos)
 
   /** Enclose this message in an `Info` container */
   def info(pos: SourcePosition) =
-    new Info(self, pos, explanation)
+    new Info(self, pos)
 
   /** Enclose this message in an `FeatureWarning` container */
   def featureWarning(pos: SourcePosition) =
-    new FeatureWarning(self, pos, explanation)
+    new FeatureWarning(self, pos)
 
   /** Enclose this message in an `UncheckedWarning` container */
   def uncheckedWarning(pos: SourcePosition) =
-    new UncheckedWarning(self, pos, explanation)
+    new UncheckedWarning(self, pos)
 
   /** Enclose this message in an `DeprecationWarning` container */
   def deprecationWarning(pos: SourcePosition) =
-    new DeprecationWarning(self, pos, explanation)
+    new DeprecationWarning(self, pos)
 
   /** Enclose this message in an `MigrationWarning` container */
   def migrationWarning(pos: SourcePosition) =
-    new MigrationWarning(self, pos, explanation)
+    new MigrationWarning(self, pos)
 }
 
 /** The fallback `Message` containing no explanation and having no `kind` */
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
index f49bebd94f07..7fd50bfdcdb5 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
@@ -15,7 +15,7 @@ object MessageContainer {
   implicit class MessageContext(val c: Context) extends AnyVal {
     def shouldExplain(cont: MessageContainer): Boolean = {
       implicit val ctx: Context = c
-      cont.explanation match {
+      cont.contained.explanation match {
         case "" => false
         case _ => ctx.settings.explain.value
       }
@@ -26,8 +26,7 @@ object MessageContainer {
 class MessageContainer(
   msgFn: => Message,
   val pos: SourcePosition,
-  val level: Int,
-  val explanation: String
+  val level: Int
 ) extends Exception with interfaces.Diagnostic {
   import MessageContainer._
   private var myMsg: String = null
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 14978449a92c..e2b99af4185d 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -17,59 +17,51 @@ object messages {
   // `MessageContainer`s to be consumed by `Reporter` ---------------------- //
   class Error(
     msgFn: => Message,
-    pos: SourcePosition,
-    explanation: String = ""
-  ) extends MessageContainer(msgFn, pos, ERROR, explanation)
+    pos: SourcePosition
+  ) extends MessageContainer(msgFn, pos, ERROR)
 
   class Warning(
     msgFn: => Message,
-    pos: SourcePosition,
-    explanation: String = ""
-  ) extends MessageContainer(msgFn, pos, WARNING, explanation)
+    pos: SourcePosition
+  ) extends MessageContainer(msgFn, pos, WARNING)
 
   class Info(
     msgFn: => Message,
-    pos: SourcePosition,
-    explanation: String = ""
-  ) extends MessageContainer(msgFn, pos, INFO, explanation)
+    pos: SourcePosition
+  ) extends MessageContainer(msgFn, pos, INFO)
 
   abstract class ConditionalWarning(
     msgFn: => Message,
-    pos: SourcePosition,
-    explanation: String = ""
-  ) extends Warning(msgFn, pos, explanation) {
+    pos: SourcePosition
+  ) extends Warning(msgFn, pos) {
     def enablingOption(implicit ctx: Context): Setting[Boolean]
   }
 
   class FeatureWarning(
     msgFn: => Message,
-    pos: SourcePosition,
-    explanation: String = ""
-  ) extends ConditionalWarning(msgFn, pos, explanation) {
+    pos: SourcePosition
+  ) extends ConditionalWarning(msgFn, pos) {
     def enablingOption(implicit ctx: Context) = ctx.settings.feature
   }
 
   class UncheckedWarning(
     msgFn: => Message,
-    pos: SourcePosition,
-    explanation: String = ""
-  ) extends ConditionalWarning(msgFn, pos, explanation) {
+    pos: SourcePosition
+  ) extends ConditionalWarning(msgFn, pos) {
     def enablingOption(implicit ctx: Context) = ctx.settings.unchecked
   }
 
   class DeprecationWarning(
     msgFn: => Message,
-    pos: SourcePosition,
-    explanation: String = ""
-  ) extends ConditionalWarning(msgFn, pos, explanation) {
+    pos: SourcePosition
+  ) extends ConditionalWarning(msgFn, pos) {
     def enablingOption(implicit ctx: Context) = ctx.settings.deprecation
   }
 
   class MigrationWarning(
     msgFn: => Message,
-    pos: SourcePosition,
-    explanation: String = ""
-  ) extends ConditionalWarning(msgFn, pos, explanation) {
+    pos: SourcePosition
+  ) extends ConditionalWarning(msgFn, pos) {
     def enablingOption(implicit ctx: Context) = ctx.settings.migration
   }
 

From 29d19ba41622b1a904d4960869866c0967db6c37 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 3 Oct 2016 14:18:46 +0200
Subject: [PATCH 47/53] Correct line extraction from SourcePosition

---
 src/dotty/tools/dotc/parsing/Parsers.scala    | 24 +++++++++----------
 .../tools/dotc/util/SourcePosition.scala      |  2 +-
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/dotty/tools/dotc/parsing/Parsers.scala b/src/dotty/tools/dotc/parsing/Parsers.scala
index 6d40107a8cc0..f22556f27d00 100644
--- a/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -1012,22 +1012,20 @@ object Parsers {
         val tryOffset = in.offset
         atPos(in.skipToken()) {
           val body = expr()
-          val handler =
+          val (handler, handlerStart) =
             if (in.token == CATCH) {
+              val pos = in.offset
               in.nextToken()
-              expr()
-            } else EmptyTree
-
-          // A block ends before RBRACE, if next token is RBRACE, simply add 1
-          def realEnd(pos: Position) =
-            if (in.token == RBRACE) pos.end + 1
-            else pos.end
+              (expr(), pos)
+            } else (EmptyTree, -1)
 
           handler match {
-            case Block(Nil, EmptyTree) => syntaxError(
-              new EmptyCatchBlock(body),
-              Position(tryOffset, realEnd(handler.pos))
-            )
+            case Block(Nil, EmptyTree) =>
+              assert(handlerStart != -1)
+              syntaxError(
+                new EmptyCatchBlock(body),
+                Position(handlerStart, handler.pos.end)
+              )
             case _ =>
           }
 
@@ -1036,7 +1034,7 @@ object Parsers {
             else {
               if (handler.isEmpty) warning(
                 EmptyCatchAndFinallyBlock(body),
-                source atPos Position(tryOffset, realEnd(body.pos))
+                source atPos Position(tryOffset, body.pos.end)
               )
               EmptyTree
             }
diff --git a/src/dotty/tools/dotc/util/SourcePosition.scala b/src/dotty/tools/dotc/util/SourcePosition.scala
index d0f9cb887e6d..a64f44417124 100644
--- a/src/dotty/tools/dotc/util/SourcePosition.scala
+++ b/src/dotty/tools/dotc/util/SourcePosition.scala
@@ -17,7 +17,7 @@ extends interfaces.SourcePosition {
 
   /** The lines of the position */
   def lines: List[Int] =
-    List.range(source.offsetToLine(start), source.offsetToLine(end)) match {
+    List.range(source.offsetToLine(start), source.offsetToLine(end + 1)) match {
       case Nil => line :: Nil
       case xs => xs
     }

From d2b620541b18bb50d2a2b89194e1778c64bba567 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 3 Oct 2016 18:21:28 +0200
Subject: [PATCH 48/53] Insert message "inline" into multiline code at point

---
 .../tools/dotc/printing/Formatting.scala      | 10 ++++--
 .../tools/dotc/printing/Highlighting.scala    |  4 ---
 .../dotc/reporting/ConsoleReporter.scala      | 12 ++++---
 .../dotc/reporting/diagnostic/Message.scala   |  8 +++++
 .../dotc/reporting/diagnostic/messages.scala  | 34 ++++++-------------
 .../tools/dotc/util/SourcePosition.scala      |  6 ++++
 6 files changed, 38 insertions(+), 36 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index 9cbf079142a1..76d2bdc18440 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -10,7 +10,7 @@ import scala.annotation.switch
 import scala.util.control.NonFatal
 import reporting.diagnostic.MessageContainer
 import util.DiffUtil
-import Highlighting.{ highlightToString => _, _ }
+import Highlighting._
 import SyntaxHighlighting._
 
 object Formatting {
@@ -165,7 +165,11 @@ object Formatting {
     }
   }
 
-  /** Turns a `Seen => String` to produce a `where: T is...` clause */
+  /** Turns a `Seen` into a `String` to produce an explanation for types on the
+    * form `where: T is...`
+    *
+    * @return string disambiguating types
+    */
   private def explanations(seen: Seen)(implicit ctx: Context): String = {
     def needsExplanation(entry: Recorded) = entry match {
       case param: PolyParam => ctx.typerState.constraint.contains(param)
@@ -245,7 +249,7 @@ object Formatting {
     val exp = wrapNonSensical(expected, expected.show)
 
     (found, expected) match {
-      case (_: RefinedType, _: RefinedType) =>
+      case (_: RefinedType, _: RefinedType) if ctx.settings.color.value != "never" =>
         DiffUtil.mkColoredTypeDiff(fnd, exp)
       case _ =>
         (hl"$fnd", hl"$exp")
diff --git a/src/dotty/tools/dotc/printing/Highlighting.scala b/src/dotty/tools/dotc/printing/Highlighting.scala
index 13e55722fa34..3bda7fb7ae64 100644
--- a/src/dotty/tools/dotc/printing/Highlighting.scala
+++ b/src/dotty/tools/dotc/printing/Highlighting.scala
@@ -9,10 +9,6 @@ object Highlighting {
 
   implicit def highlightShow(h: Highlight)(implicit ctx: Context): String =
     h.show
-  implicit def highlightToString(h: Highlight): String =
-    h.toString
-  implicit def hbufToString(hb: HighlightBuffer): String =
-    hb.toString
 
   abstract class Highlight(private val highlight: String) {
     def text: String
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 6ebd53beaec3..82edd6a83a95 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -32,9 +32,10 @@ class ConsoleReporter(
   def stripColor(str: String): String =
     str.replaceAll("\u001B\\[[;\\d]*m", "")
 
-  def sourceLines(pos: SourcePosition)(implicit ctx: Context): (List[String], Int) = {
+  def sourceLines(pos: SourcePosition)(implicit ctx: Context): (List[String], List[String], Int) = {
     var maxLen = Int.MinValue
-    val lines = pos.lines
+    def render(xs: List[Int]) =
+      xs.map(pos.source.offsetToLine(_))
       .map { lineNbr =>
         val prefix = s"${lineNbr + 1} |"
         maxLen = math.max(maxLen, prefix.length)
@@ -45,7 +46,8 @@ class ConsoleReporter(
         hl"$lnum$line"
       }
 
-    (lines, maxLen)
+    val (before, after) = pos.beforeAndAfterPoint
+    (render(before), render(after), maxLen)
   }
 
   def columnMarker(pos: SourcePosition, offset: Int)(implicit ctx: Context) = {
@@ -95,11 +97,11 @@ class ConsoleReporter(
   def printMessageAndPos(msg: Message, pos: SourcePosition, diagnosticLevel: String)(implicit ctx: Context): Unit = {
     printMessage(posStr(pos, diagnosticLevel, msg))
     if (pos.exists) {
-      val (srcLines, offset) = sourceLines(pos)
+      val (srcBefore, srcAfter, offset) = sourceLines(pos)
       val marker = columnMarker(pos, offset)
       val err = errorMsg(pos, msg.msg, offset)
 
-      printMessage((srcLines ::: marker :: err :: Nil).mkString("\n"))
+      printMessage((srcBefore ::: marker :: err :: srcAfter).mkString("\n"))
     } else printMessage(msg.msg)
   }
 
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
index bdc899ea8b42..8b1f6567309f 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/Message.scala
@@ -15,6 +15,14 @@ object Message {
     new NoExplanation(str)
 }
 
+/** A `Message` contains all semantic information necessary to easily
+  * comprehend what caused the message to be logged. Each message can be turned
+  * into a `MessageContainer` which contains the log level and can later be
+  * consumed by a subclass of `Reporter`.
+  *
+  * @param errorId a unique number identifying the message, this will later be
+  *                used to reference documentation online
+  */
 abstract class Message(val errorId: Int) { self =>
   import messages._
 
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index e2b99af4185d..cc062ff92bde 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -90,8 +90,10 @@ object messages {
       }
 
       val code1 =
-        s"""|try $tryString catch {
-            |  case t: Throwable => ???
+        s"""|import scala.util.control.NonFatal
+            |
+            |try $tryString catch {
+            |  case NonFatal(e) => ???
             |}""".stripMargin
 
       val code2 =
@@ -108,7 +110,10 @@ object messages {
            |It is also possible to follow a ${"try"} immediately by a ${"finally"} - letting the
            |exception propagate - but still allowing for some clean up in ${"finally"}:
            |
-           |$code2""".stripMargin
+           |$code2
+           |
+           |It is recommended to use the ${"NonFatal"} extractor to catch all exceptions as it
+           |correctly handles transfer functions like ${"return"}.""".stripMargin
     }
   }
 
@@ -133,29 +138,10 @@ object messages {
     val kind = "Syntax"
     val msg =
       hl"""${"with"} as a type operator has been deprecated; use `&' instead"""
-    val explanation = {
-      val codeBlock1 =
-        """|trait A {
-           |  type T = Int
-           |}
-           |
-           |trait B {
-           |  type T = Double
-           |}""".stripMargin
-
+    val explanation =
       hl"""|Dotty introduces intersection types - `&' types. These replace the
            |use of the ${"with"} keyword. There are a few differences in
-           |semantics between intersection types and using `${"with"}'.
-           |
-           |`${"A with B"}' is ordered, `${"A & B"}' is not.
-           |
-           |In:
-           |
-           |$codeBlock1
-           |
-           |The type of `${"T"}' in `${"A with B"}' is ${"Int"} whereas in `${"A & B"}'
-           |the type of `${"T"}' is ${"Int & Double"}.""".stripMargin
-    }
+           |semantics between intersection types and using `${"with"}'.""".stripMargin
   }
 
   case class CaseClassMissingParamList(cdef: untpd.TypeDef)(implicit ctx: Context)
diff --git a/src/dotty/tools/dotc/util/SourcePosition.scala b/src/dotty/tools/dotc/util/SourcePosition.scala
index a64f44417124..595ea34ca168 100644
--- a/src/dotty/tools/dotc/util/SourcePosition.scala
+++ b/src/dotty/tools/dotc/util/SourcePosition.scala
@@ -22,9 +22,15 @@ extends interfaces.SourcePosition {
       case xs => xs
     }
 
+  def lineOffsets: List[Int] =
+    lines.map(source.lineToOffset(_))
+
   def lineContent(lineNumber: Int): String =
     source.lineContent(source.lineToOffset(lineNumber))
 
+  def beforeAndAfterPoint: (List[Int], List[Int]) =
+    lineOffsets.partition(_ < point)
+
   /** The column of the position, starting at 0 */
   def column: Int = source.column(point)
 

From e754a2d790e0cf5ab2c1480166a42cbb908add0f Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Tue, 4 Oct 2016 15:51:15 +0200
Subject: [PATCH 49/53] Change `typeDiff` to highlight changes less than 50%

---
 src/dotty/tools/dotc/printing/Formatting.scala | 12 ++++++------
 src/dotty/tools/dotc/util/DiffUtil.scala       | 15 ++++++++++-----
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index 76d2bdc18440..719c23e847e5 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -242,17 +242,17 @@ object Formatting {
     * correct `Context` for printing should also be passed when calling the
     * method.
     *
-    * @return the (found, expected) with coloring to highlight the difference
+    * @return the (found, expected, changePercentage) with coloring to
+    *         highlight the difference
     */
   def typeDiff(found: Type, expected: Type)(implicit ctx: Context): (String, String) = {
     val fnd = wrapNonSensical(found, found.show)
     val exp = wrapNonSensical(expected, expected.show)
 
-    (found, expected) match {
-      case (_: RefinedType, _: RefinedType) if ctx.settings.color.value != "never" =>
-        DiffUtil.mkColoredTypeDiff(fnd, exp)
-      case _ =>
-        (hl"$fnd", hl"$exp")
+    DiffUtil.mkColoredTypeDiff(fnd, exp) match {
+      case _ if ctx.settings.color.value == "never" => (fnd, exp)
+      case (fnd, exp, change) if change < 0.5 => (fnd, exp)
+      case _ => (fnd, exp)
     }
   }
 }
diff --git a/src/dotty/tools/dotc/util/DiffUtil.scala b/src/dotty/tools/dotc/util/DiffUtil.scala
index 8bb39c88aa4c..b55aee719045 100644
--- a/src/dotty/tools/dotc/util/DiffUtil.scala
+++ b/src/dotty/tools/dotc/util/DiffUtil.scala
@@ -32,8 +32,9 @@ object DiffUtil {
     }
 
 
-  /** @return a tuple of the (found, expected) diffs as strings */
-  def mkColoredTypeDiff(found: String, expected: String): (String, String) = {
+  /** @return a tuple of the (found, expected, changedPercentage) diffs as strings */
+  def mkColoredTypeDiff(found: String, expected: String): (String, String, Double) = {
+    var totalChange = 0
     val foundTokens   = splitTokens(found, Nil).toArray
     val expectedTokens = splitTokens(expected, Nil).toArray
 
@@ -42,15 +43,19 @@ object DiffUtil {
 
     val exp = diffExp.collect {
       case Unmodified(str) => str
-      case Inserted(str) => ADDITION_COLOR + str + ANSI_DEFAULT
+      case Inserted(str) =>
+        totalChange += str.length
+        ADDITION_COLOR + str + ANSI_DEFAULT
     }.mkString
 
     val fnd = diffAct.collect {
       case Unmodified(str) => str
-      case Inserted(str) => DELETION_COLOR + str + ANSI_DEFAULT
+      case Inserted(str) =>
+        totalChange += str.length
+        DELETION_COLOR + str + ANSI_DEFAULT
     }.mkString
 
-    (fnd, exp)
+    (fnd, exp, totalChange.toDouble / (expected.length + found.length))
   }
 
   def mkColoredCodeDiff(code: String, lastCode: String, printDiffDel: Boolean): String = {

From 45a2df1033c8cb13a3d80f429e31872e3d4174e1 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 7 Oct 2016 13:47:15 +0200
Subject: [PATCH 50/53] Fix TreeChecker mismatch string

---
 src/dotty/tools/dotc/transform/TreeChecker.scala | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/dotty/tools/dotc/transform/TreeChecker.scala b/src/dotty/tools/dotc/transform/TreeChecker.scala
index 4b3927ccfcf9..fd8e41dc3fa9 100644
--- a/src/dotty/tools/dotc/transform/TreeChecker.scala
+++ b/src/dotty/tools/dotc/transform/TreeChecker.scala
@@ -425,10 +425,11 @@ class TreeChecker extends Phase with SymTransformer {
           !tree.isEmpty &&
           !isPrimaryConstructorReturn &&
           !pt.isInstanceOf[FunProto])
-        assert(tree.tpe <:< pt,
-            i"""error at ${sourcePos(tree.pos)}
-               |${err.typeMismatchStr(tree.tpe, pt)}
-               |tree = $tree""")
+        assert(tree.tpe <:< pt, {
+          val mismatch = err.typeMismatchMsg(tree.tpe, pt)
+          i"""|${mismatch.msg}
+              |tree = $tree""".stripMargin
+        })
       tree
     }
   }

From b9e03b8d9246134afeacc925651139c079275479 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Fri, 7 Oct 2016 13:47:27 +0200
Subject: [PATCH 51/53] Remove unnecessary printing of hints for `-explain`

---
 src/dotty/tools/dotc/printing/Formatting.scala      |  2 +-
 .../tools/dotc/reporting/ConsoleReporter.scala      | 13 ++++++++-----
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/dotty/tools/dotc/printing/Formatting.scala b/src/dotty/tools/dotc/printing/Formatting.scala
index 719c23e847e5..e7968b14a949 100644
--- a/src/dotty/tools/dotc/printing/Formatting.scala
+++ b/src/dotty/tools/dotc/printing/Formatting.scala
@@ -90,7 +90,7 @@ object Formatting {
       }
   }
 
-  private def wrapNonSensical(arg: Any, str: String)(implicit ctx: Context): String = {
+  private def wrapNonSensical(arg: Any /* Type | Symbol */, str: String)(implicit ctx: Context): String = {
     import MessageContainer._
     def isSensical(arg: Any): Boolean = arg match {
       case tpe: Type =>
diff --git a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
index 82edd6a83a95..da3df6984954 100644
--- a/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
+++ b/src/dotty/tools/dotc/reporting/ConsoleReporter.scala
@@ -94,7 +94,7 @@ class ConsoleReporter(
     }).show else ""
 
   /** Prints the message with the given position indication. */
-  def printMessageAndPos(msg: Message, pos: SourcePosition, diagnosticLevel: String)(implicit ctx: Context): Unit = {
+  def printMessageAndPos(msg: Message, pos: SourcePosition, diagnosticLevel: String)(implicit ctx: Context): Boolean = {
     printMessage(posStr(pos, diagnosticLevel, msg))
     if (pos.exists) {
       val (srcBefore, srcAfter, offset) = sourceLines(pos)
@@ -103,6 +103,7 @@ class ConsoleReporter(
 
       printMessage((srcBefore ::: marker :: err :: srcAfter).mkString("\n"))
     } else printMessage(msg.msg)
+    true
   }
 
   def printExplanation(m: Message)(implicit ctx: Context): Unit = {
@@ -114,11 +115,13 @@ class ConsoleReporter(
   }
 
   override def doReport(m: MessageContainer)(implicit ctx: Context): Unit = {
-    m match {
+    val didPrint = m match {
       case m: Error =>
-        printMessageAndPos(m.contained, m.pos, "Error")
+        val didPrint = printMessageAndPos(m.contained, m.pos, "Error")
         if (ctx.settings.prompt.value) displayPrompt()
+        didPrint
       case m: ConditionalWarning if !m.enablingOption.value =>
+        false
       case m: FeatureWarning =>
         printMessageAndPos(m.contained, m.pos, "Feature Warning")
       case m: DeprecationWarning =>
@@ -133,9 +136,9 @@ class ConsoleReporter(
         printMessageAndPos(m.contained, m.pos, "Info")
     }
 
-    if (ctx.shouldExplain(m))
+    if (didPrint && ctx.shouldExplain(m))
       printExplanation(m.contained)
-    else if (m.contained.explanation.nonEmpty)
+    else if (didPrint && m.contained.explanation.nonEmpty)
       printMessage("\nlonger explanation available when compiling with `-explain`")
   }
 

From d490f7d9ebe072b5ade305265100c7bc433885a9 Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Sat, 8 Oct 2016 00:22:08 +0200
Subject: [PATCH 52/53] Add Levenshtein distance for member values and types

---
 .../dotc/reporting/diagnostic/messages.scala  | 71 ++++++++++++++++++-
 src/dotty/tools/dotc/typer/TypeAssigner.scala |  4 +-
 tests/repl/errmsgs.check                      |  5 ++
 3 files changed, 76 insertions(+), 4 deletions(-)

diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index cc062ff92bde..9cfac4801853 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -199,13 +199,78 @@ object messages {
   case class TypeMismatch(found: Type, expected: Type, whyNoMatch: String = "", implicitFailure: String = "")(implicit ctx: Context)
   extends Message(7) {
     val kind = "Type Mismatch"
-    private val (where, printCtx) = Formatting.disambiguateTypes(found, expected)
-    private val (fnd, exp) = Formatting.typeDiff(found, expected)(printCtx)
-    val msg =
+    val msg = {
+      val (where, printCtx) = Formatting.disambiguateTypes(found, expected)
+      val (fnd, exp) = Formatting.typeDiff(found, expected)(printCtx)
       s"""|found:    $fnd
           |required: $exp
           |
           |$where""".stripMargin + whyNoMatch + implicitFailure
+    }
+
+    val explanation = ""
+  }
+
+  case class NotAMember(site: Type, name: Name, selected: String)(implicit ctx: Context)
+  extends Message(8) {
+    val kind = "Member Not Found"
+
+    val msg = {
+      import core.Flags._
+      val maxDist = 3
+      val decls = site.decls.flatMap { sym =>
+        if (sym.is(Synthetic | PrivateOrLocal) || sym.isConstructor) Nil
+        else List((sym.name.show, sym))
+      }
+
+      // Calculate Levenshtein distance
+      def distance(n1: Iterable[_], n2: Iterable[_]) =
+        n1.foldLeft(List.range(0, n2.size)) { (prev, x) =>
+          (prev zip prev.tail zip n2).scanLeft(prev.head + 1) {
+            case (h, ((d, v), y)) => math.min(
+              math.min(h + 1, v + 1),
+              if (x == y) d else d + 1
+            )
+          }
+        }.last
+
+      // Count number of wrong characters
+      def incorrectChars(x: (String, Int, Symbol)): (String, Symbol, Int) = {
+        val (currName, _, sym) = x
+        val matching = name.show.zip(currName).foldLeft(0) {
+          case (acc, (x,y)) => if (x != y) acc + 1 else acc
+        }
+        (currName, sym, matching)
+      }
+
+      // Get closest match in `site`
+      val closest =
+        decls
+        .map { case (n, sym) => (n, distance(n, name.show), sym) }
+        .collect { case (n, dist, sym) if dist <= maxDist => (n, dist, sym) }
+        .groupBy(_._2).toList
+        .sortBy(_._1)
+        .headOption.map(_._2).getOrElse(Nil)
+        .map(incorrectChars).toList
+        .sortBy(_._3)
+        .take(1).map { case (n, sym, _) => (n, sym) }
+
+      val siteName = site match {
+        case site: NamedType => site.name.show
+        case site => i"$site"
+      }
+
+      val closeMember = closest match {
+        case (n, sym) :: Nil => hl""" - did you mean `${s"$siteName.$n"}`?"""
+        case Nil => ""
+        case _ => assert(
+          false,
+          "Could not single out one distinct member to match on input with"
+        )
+      }
+
+      ex"$selected `$name` is not a member of $site$closeMember"
+    }
 
     val explanation = ""
   }
diff --git a/src/dotty/tools/dotc/typer/TypeAssigner.scala b/src/dotty/tools/dotc/typer/TypeAssigner.scala
index 0c55d977e67a..262d3f7312ef 100644
--- a/src/dotty/tools/dotc/typer/TypeAssigner.scala
+++ b/src/dotty/tools/dotc/typer/TypeAssigner.scala
@@ -12,6 +12,8 @@ import config.Printers.typr
 import ast.Trees._
 import NameOps._
 import collection.mutable
+import reporting.diagnostic.Message
+import reporting.diagnostic.messages._
 
 trait TypeAssigner {
   import tpd._
@@ -220,7 +222,7 @@ trait TypeAssigner {
           else ""
         ctx.error(
           if (name == nme.CONSTRUCTOR) ex"$site does not have a constructor"
-          else ex"$kind $name is not a member of $site$addendum",
+          else NotAMember(site, name, kind),
           pos)
       }
       ErrorType
diff --git a/tests/repl/errmsgs.check b/tests/repl/errmsgs.check
index 066d98d0f91d..2bcb40eb0c64 100644
--- a/tests/repl/errmsgs.check
+++ b/tests/repl/errmsgs.check
@@ -73,4 +73,9 @@ scala> abstract class C {
    |                     
    |                     where:    T  is a type in the initalizer of value s which is an alias of String
    |                               T' is a type in method f which is an alias of Int
+scala> class Foo() { def bar: Int = 1 }; val foo = new Foo(); foo.barr
+-- [E008] Member Not Found Error: <console> ----------------------------------------------------------------------------
+4 |class Foo() { def bar: Int = 1 }; val foo = new Foo(); foo.barr
+  |                                                       ^^^^^^^^
+  |                                                value `barr` is not a member of Foo(foo) - did you mean `foo.bar`?
 scala> :quit

From 550c643a2a9ad785318e9a727ddc82e3e2f244aa Mon Sep 17 00:00:00 2001
From: Felix Mulder <felix.mulder@gmail.com>
Date: Mon, 10 Oct 2016 21:31:53 +0200
Subject: [PATCH 53/53] Adopt delegating reporter to new scheme

---
 .../main/scala/xsbt/DelegatingReporter.scala  | 28 ++++++++++---------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/bridge/src/main/scala/xsbt/DelegatingReporter.scala b/bridge/src/main/scala/xsbt/DelegatingReporter.scala
index 726570d71d91..446ef287ec8c 100644
--- a/bridge/src/main/scala/xsbt/DelegatingReporter.scala
+++ b/bridge/src/main/scala/xsbt/DelegatingReporter.scala
@@ -6,6 +6,8 @@ package xsbt
 import dotty.tools._
 import dotc._
 import reporting._
+import reporting.diagnostic.MessageContainer
+import reporting.diagnostic.messages
 import core.Contexts._
 
 import xsbti.{Maybe, Position}
@@ -16,19 +18,19 @@ final class DelegatingReporter(delegate: xsbti.Reporter) extends Reporter
 
   override def printSummary(implicit ctx: Context): Unit = delegate.printSummary()
 
-  def doReport(d: Diagnostic)(implicit ctx: Context): Unit = {
-    val severity = 
-      d match {
-        case _: Reporter.Error   => xsbti.Severity.Error
-        case _: Reporter.Warning => xsbti.Severity.Warn
+  def doReport(cont: MessageContainer)(implicit ctx: Context): Unit = {
+    val severity =
+      cont match {
+        case _: messages.Error   => xsbti.Severity.Error
+        case _: messages.Warning => xsbti.Severity.Warn
         case _                   => xsbti.Severity.Info
       }
-    val pos = 
-      if (d.pos.exists) Some(d.pos)
+    val pos =
+      if (cont.pos.exists) Some(cont.pos)
       else None
 
-    val file = 
-      if (d.pos.source.file.exists) Option(d.pos.source.file.file)
+    val file =
+      if (cont.pos.source.file.exists) Option(cont.pos.source.file.file)
       else None
 
     val offset0 = pos.map(_.point)
@@ -43,16 +45,16 @@ final class DelegatingReporter(delegate: xsbti.Reporter) extends Reporter
       def sourcePath: Maybe[String] = maybe(file.map(_.getPath))
     }
 
-    delegate.log(position, d.message, severity)
+    delegate.log(position, cont.message, severity)
   }
 
-  private[this] def maybe[T](opt: Option[T]): Maybe[T] = opt match { 
+  private[this] def maybe[T](opt: Option[T]): Maybe[T] = opt match {
     case None => Maybe.nothing[T]
     case Some(s) => Maybe.just[T](s)
   }
   import java.lang.{ Integer => I }
-  private[this] def maybeInt(opt: Option[Int]): Maybe[I] = opt match { 
+  private[this] def maybeInt(opt: Option[Int]): Maybe[I] = opt match {
     case None => Maybe.nothing[I]
     case Some(s) => Maybe.just[I](s)
   }
-}
\ No newline at end of file
+}