Make ErrorMessageID a Scala enum

Author: odersky

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

@@ -119,7 +119,7 @@ trait MessageRendering {
         else s"${pos.source.file.toString}: offset ${pos.start} (missing source file)"
       val errId =
         if (message.errorId ne ErrorMessageID.NoExplanationID) {
-          val errorNumber = message.errorId.errorNumber()
+          val errorNumber = message.errorId.errorNumber
           s"[E${"0" * (3 - errorNumber.toString.length) + errorNumber}] "
         } else ""
       val kind =

compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java renamed to compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.scala

@@ -1,10 +1,10 @@
-package dotty.tools.dotc.reporting.diagnostic;
+package dotty.tools.dotc.reporting.diagnostic
 
 /** Unique IDs identifying the messages */
-public enum ErrorMessageID {
-
-    // IMPORTANT: Add new IDs only at the end and never remove IDs
+enum ErrorMessageID {
 
+  // IMPORTANT: Add new IDs only at the end and never remove IDs
+  case
     LazyErrorId, // // errorNumber: -2
     NoExplanationID, // errorNumber: -1
 
@@ -146,10 +146,6 @@ public enum ErrorMessageID {
     StableIdentPatternID,
     StaticFieldsShouldPrecedeNonStaticID,
     IllegalSuperAccessorID
-    ;
-
-    public int errorNumber() {
-        return ordinal() - 2;
-    }
 
+  def errorNumber = ordinal - 2
 }