From 44b8b5c06cff8dd6282d8156ee7b5fb4edaf1068 Mon Sep 17 00:00:00 2001
From: Adam Trousdale <adam@tootle.co.uk>
Date: Wed, 21 Dec 2016 09:49:53 +0000
Subject: [PATCH 1/2] Added error messages - Parsers.scala:712

---
 .../dotty/tools/dotc/parsing/Parsers.scala    |  2 +-
 .../dotc/reporting/diagnostic/messages.scala  | 24 ++++++++++++++++---
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
index 76f82d8af242..57dd1ea20b07 100644
--- a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -730,7 +730,7 @@ object Parsers {
 
       in.token match {
         case ARROW => functionRest(t :: Nil)
-        case FORSOME => syntaxError("existential types no longer supported; use a wildcard type or dependent type instead"); t
+        case FORSOME => syntaxError(ExistentialTypesNoLongerSupported()); t
         case _ => t
       }
     }
diff --git a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 9dda233bffe6..07ba118719b8 100644
--- a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -5,10 +5,9 @@ package diagnostic
 
 import dotc.core._
 import Contexts.Context, Decorators._, Symbols._, Names._, NameOps._, Types._
-import util.{SourceFile, NoSource}
-import util.{SourcePosition, NoSourcePosition}
+import util.SourcePosition
 import config.Settings.Setting
-import interfaces.Diagnostic.{ERROR, WARNING, INFO}
+import interfaces.Diagnostic.{ERROR, INFO, WARNING}
 import printing.Highlighting._
 import printing.Formatting
 
@@ -901,4 +900,23 @@ object messages {
     val msg = hl"trying to define package with same name as `$existing`"
     val explanation = ""
   }
+
+  case class ExistentialTypesNoLongerSupported()(implicit ctx: Context) extends Message(34) {
+    val kind = "Syntax"
+    val msg = "Existential types are no longer supported - use a wildcard or dependent type instead"
+    val explanation =
+      hl"""| The use of existential types is no longer supported and a wildcard or dependent type should be used instead
+           |
+           | For example:
+           |
+           | Instead of using ${"forSome"} to specify a type variable
+           |
+           | ${"List[T forSome { type T }]"}
+           |
+           | Try using a wildcard type variable
+           |
+           | ${"List[_]"}
+           |"""
+  }
+
 }

From e3da9482fc8323337131661611dde76e52121945 Mon Sep 17 00:00:00 2001
From: Adam Trousdale <adam@tootle.co.uk>
Date: Wed, 21 Dec 2016 19:36:12 +0000
Subject: [PATCH 2/2] Tidied up imports and formatting

---
 .../dotc/reporting/diagnostic/messages.scala  | 20 +++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 07ba118719b8..b55b7e8683f2 100644
--- a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -7,7 +7,7 @@ import dotc.core._
 import Contexts.Context, Decorators._, Symbols._, Names._, NameOps._, Types._
 import util.SourcePosition
 import config.Settings.Setting
-import interfaces.Diagnostic.{ERROR, INFO, WARNING}
+import interfaces.Diagnostic.{ERROR, WARNING, INFO}
 import printing.Highlighting._
 import printing.Formatting
 
@@ -903,19 +903,23 @@ object messages {
 
   case class ExistentialTypesNoLongerSupported()(implicit ctx: Context) extends Message(34) {
     val kind = "Syntax"
-    val msg = "Existential types are no longer supported - use a wildcard or dependent type instead"
+    val msg =
+      hl"""|Existential types are no longer supported -
+           |use a wildcard or dependent type instead"""
     val explanation =
-      hl"""| The use of existential types is no longer supported and a wildcard or dependent type should be used instead
+      hl"""|The use of existential types is no longer supported.
+           |
+           |You should use a wildcard or dependent type instead.
            |
-           | For example:
+           |For example:
            |
-           | Instead of using ${"forSome"} to specify a type variable
+           |Instead of using ${"forSome"} to specify a type variable
            |
-           | ${"List[T forSome { type T }]"}
+           |${"List[T forSome { type T }]"}
            |
-           | Try using a wildcard type variable
+           |Try using a wildcard type variable
            |
-           | ${"List[_]"}
+           |${"List[_]"}
            |"""
   }