Fix #3784 : add an enum for Error kind

compiler/src/dotty/tools/dotc/reporting/MessageRendering.scala

@@ -6,12 +6,12 @@ import core.Contexts.Context
 import core.Decorators._
 import printing.Highlighting.{Blue, Red}
 import printing.SyntaxHighlighting
-import diagnostic.{ErrorMessageID, Message, MessageContainer, NoExplanation}
+import diagnostic._
 import diagnostic.messages._
 import util.SourcePosition
-import util.Chars.{ LF, CR, FF, SU }
-import scala.annotation.switch
+import util.Chars.{CR, FF, LF, SU}
 
+import scala.annotation.switch
 import scala.collection.mutable
 
 trait MessageRendering {
@@ -117,7 +117,7 @@ trait MessageRendering {
           s"[E${"0" * (3 - errorNumber.toString.length) + errorNumber}] "
         } else ""
       val kind =
-        if (message.kind == "") diagnosticLevel
+        if (message.kind == ErrorCategory.NoKind) diagnosticLevel
         else s"${message.kind} $diagnosticLevel"
       val prefix = s"-- ${errId}${kind}: $file "
 

compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorCategory.scala

@@ -0,0 +1,22 @@
+package dotty.tools.dotc.reporting.diagnostic
+
+sealed abstract class ErrorCategory(name: String) {
+  override def toString: String = name
+}
+object ErrorCategory {
+
+  val NoKind = new ErrorCategory("") {}
+
+  val Compatibility = new ErrorCategory("Compatibility") {}
+  val DefinitionNotFound = new ErrorCategory("Definition Not Found") {}
+  val DuplicateSymbol = new ErrorCategory("Duplicate Symbol") {}
+  val MatchCaseUnreachable = new ErrorCategory("Match case Unreachable") {}
+  val MemberNotFound = new ErrorCategory("Member Not Found") {}
+  val Naming = new ErrorCategory("Naming") {}
+  val PatternMatchExhaustivity = new ErrorCategory("Pattern Match Exhaustivity") {}
+  val Reference = new ErrorCategory("Reference") {}
+  val Syntax = new ErrorCategory("Syntax") {}
+  val TypeMismatch = new ErrorCategory("Type Mismatch") {}
+  val UnboundIdentifier = new ErrorCategory("Unbound Identifier") {}
+  val Usage = new ErrorCategory("Usage") {}
+}

compiler/src/dotty/tools/dotc/reporting/diagnostic/Message.scala

@@ -48,7 +48,7 @@ abstract class Message(val errorId: ErrorMessageID) { self =>
   /** The kind of the error message is something like "Syntax" or "Type
     * Mismatch"
     */
-  def kind: String
+  def kind: ErrorCategory
 
   /** 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
@@ -117,7 +117,7 @@ class ExtendMessage(_msg: () => Message)(f: String => String) { self =>
 /** The fallback `Message` containing no explanation and having no `kind` */
 class NoExplanation(val msg: String) extends Message(ErrorMessageID.NoExplanationID) {
   val explanation = ""
-  val kind = ""
+  val kind = ErrorCategory.NoKind
 
   override def toString(): String = s"NoExplanation($msg)"
 }