stable identifier message

Author: hermesespinola

compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java

@@ -141,7 +141,8 @@ public enum ErrorMessageID {
     LazyStaticFieldID,
     StaticOverridingNonStaticMembersID,
     OverloadInRefinementID,
-    NoMatchingOverloadID
+    NoMatchingOverloadID,
+    StableIdentPatternID
     ;
 
     public int errorNumber() {

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

@@ -2191,4 +2191,12 @@ object messages {
     val kind: String = "Type Mismatch"
     val explanation: String = ""
   }
+  case class StableIdentPattern(tree: untpd.Tree, pt: Type)(implicit val ctx: Context)
+    extends Message(StableIdentPatternID) {
+    override def kind: String = "Syntax"
+    override def msg: String = {
+      hl"""|Stable identifier required, but ${tree.show} found"""
+    }
+    override def explanation: String = ""
+  }
 }

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -414,7 +414,7 @@ class Typer extends Namer
         !pt.isInstanceOf[ApplyingProto] &&
         !tree.tpe.isStable &&
         !isWildcardArg(tree))
-      ctx.error(s"stable identifier required, but ${tree.show} found", tree.pos)
+      ctx.error(StableIdentPattern(tree, pt), tree.pos)
 
     tree
   }