Merge pull request #14331 from dotty-staging/fix-14326

Avoid misleading error message

Author: odersky

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -3758,11 +3758,11 @@ object Parsers {
         }
         else Nil
       possibleTemplateStart()
-      if (isEnum) {
-        val (self, stats) = withinEnum(templateBody())
+      if isEnum then
+        val (self, stats) = withinEnum(templateBody(parents))
         Template(constr, parents, derived, self, stats)
-      }
-      else templateBodyOpt(constr, parents, derived)
+      else
+        templateBodyOpt(constr, parents, derived)
     }
 
     /** TemplateOpt = [Template]
@@ -3785,15 +3785,15 @@ object Parsers {
     def templateBodyOpt(constr: DefDef, parents: List[Tree], derived: List[Tree]): Template =
       val (self, stats) =
         if in.isNestedStart then
-          templateBody()
+          templateBody(parents)
         else
           checkNextNotIndented()
           (EmptyValDef, Nil)
       Template(constr, parents, derived, self, stats)
 
-    def templateBody(rewriteWithColon: Boolean = true): (ValDef, List[Tree]) =
+    def templateBody(parents: List[Tree], rewriteWithColon: Boolean = true): (ValDef, List[Tree]) =
       val r = inDefScopeBraces(templateStatSeq(), rewriteWithColon)
-      if in.token == WITH then
+      if in.token == WITH && parents.isEmpty then
         syntaxError(EarlyDefinitionsNotSupported())
         in.nextToken()
         template(emptyConstructor)
@@ -3802,7 +3802,7 @@ object Parsers {
     /** with Template, with EOL <indent> interpreted */
     def withTemplate(constr: DefDef, parents: List[Tree]): Template =
       accept(WITH)
-      val (self, stats) = templateBody(rewriteWithColon = false)
+      val (self, stats) = templateBody(parents, rewriteWithColon = false)
       Template(constr, parents, Nil, self, stats)
         .withSpan(Span(constr.span.orElse(parents.head.span).start, in.lastOffset))
 
@@ -4045,7 +4045,7 @@ object Parsers {
       EmptyTree
     }
 
-    override def templateBody(rewriteWithColon: Boolean): (ValDef, List[Thicket]) = {
+    override def templateBody(parents: List[Tree], rewriteWithColon: Boolean): (ValDef, List[Thicket]) = {
       skipBraces()
       (EmptyValDef, List(EmptyTree))
     }

tests/neg/parent-refinement.check

@@ -0,0 +1,4 @@
+-- Error: tests/neg/parent-refinement.scala:5:2 ------------------------------------------------------------------------
+5 |  with Ordered[Year] { // error
+  |  ^^^^
+  |  end of toplevel definition expected but 'with' found

tests/neg/parent-refinement.scala

@@ -0,0 +1,7 @@
+
+trait Id { type Value }
+case class Year(value: Int) extends AnyVal
+  with Id { type Value = Int }
+  with Ordered[Year] { // error
+
+}