Remove ErrorMessageID.LazyErrorId and improve doc

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

@@ -1,12 +1,16 @@
 package dotty.tools.dotc.reporting
 
-/** Unique IDs identifying the messages
+//////////////////////////////////////////////////////////////////////////
+// IMPORTANT                                                            //
+// Only add new IDs at end of the enumeration list and never remove IDs //
+//////////////////////////////////////////////////////////////////////////
+
+/** Unique IDs identifying the messages, this will be used to reference documentation online.
+ *
  *  @param isActive Whether or not the compile still emits this ErrorMessageID
  **/
 enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMessageID]:
 
-  // IMPORTANT: Add new IDs only at the end and never remove IDs
-  case LazyErrorId // // errorNumber: -2
   case NoExplanationID // errorNumber: -1
 
   case EmptyCatchOrFinallyBlockID extends ErrorMessageID(isActive = false) // errorNumber: 0
@@ -19,8 +23,8 @@ enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMe
   case TypeMismatchID // errorNumber: 7
   case NotAMemberID // errorNumber: 8
   case EarlyDefinitionsNotSupportedID // errorNumber: 9
-  case TopLevelImplicitClassID extends ErrorMessageID(isActive = false) // errorNumber: 10 
-  case ImplicitCaseClassID // errorNumber: 11 
+  case TopLevelImplicitClassID extends ErrorMessageID(isActive = false) // errorNumber: 10
+  case ImplicitCaseClassID // errorNumber: 11
   case ImplicitClassPrimaryConstructorArityID // errorNumber: 12
   case ObjectMayNotHaveSelfTypeID // errorNumber: 13
   case TupleTooLongID extends ErrorMessageID(isActive = false) // errorNumber: 14
@@ -97,7 +101,7 @@ enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMe
   case FunctionTypeNeedsNonEmptyParameterListID // errorNumber: 85
   case WrongNumberOfParametersID // errorNumber: 86
   case DuplicatePrivateProtectedQualifierID // errorNumber: 87
-  case ExpectedStartOfTopLevelDefinitionID // errorNumber: 88 
+  case ExpectedStartOfTopLevelDefinitionID // errorNumber: 88
   case MissingReturnTypeWithReturnStatementID // errorNumber: 89
   case NoReturnFromInlineableID // errorNumber: 90
   case ReturnOutsideMethodDefinitionID // errorNumber: 91
@@ -180,12 +184,12 @@ enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMe
   case ImplicitSearchTooLargeID // errorNumber: 168
   case TargetNameOnTopLevelClassID // errorNumber: 169
 
-  def errorNumber = ordinal - 2
+  def errorNumber = ordinal - 1
 
 object ErrorMessageID:
   def fromErrorNumber(n: Int): Option[ErrorMessageID] =
-    val enumId = n + 2
-    if enumId >= 2 && enumId < ErrorMessageID.values.length then
+    val enumId = n + 1
+    if enumId >= 1 && enumId < ErrorMessageID.values.length then
       Some(fromOrdinal(enumId))
     else
       None

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

@@ -43,7 +43,7 @@ object Message {
   * Instead use the `persist` method to create an instance that does not keep a
   * reference to these contexts.
   *
-  * @param errorId a unique id identifying the message, this will later be
+  * @param errorId a unique id identifying the message, this will be
   *                used to reference documentation online
   */
 abstract class Message(val errorId: ErrorMessageID) { self =>