Avoid "value of type <notype> does not take parameters" errors

Author: odersky

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

@@ -96,6 +96,12 @@ object ErrorReporting {
 
     def exprStr(tree: Tree): String = refStr(tree.tpe)
 
+    def takesNoParamsStr(tree: Tree, kind: String) =
+      if (tree.tpe.widen.exists)
+        i"${exprStr(tree)} does not take ${kind}parameters"
+      else
+        i"undefined: $tree # ${tree.uniqueId}: ${tree.tpe.toString}"
+
     def patternConstrStr(tree: Tree): String = ???
 
     def typeMismatch(tree: Tree, pt: Type, implicitFailure: SearchFailure = NoImplicitMatches): Tree =

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

@@ -340,7 +340,7 @@ trait TypeAssigner {
         else
           errorType(i"wrong number of arguments for $fntpe: ${fn.tpe}, expected: ${fntpe.paramInfos.length}, found: ${args.length}", tree.pos)
       case t =>
-        errorType(i"${err.exprStr(fn)} does not take parameters", tree.pos)
+        errorType(err.takesNoParamsStr(fn, ""), tree.pos)
     }
     tree.withType(ownType)
   }
@@ -396,7 +396,7 @@ trait TypeAssigner {
           else wrongNumberOfTypeArgs(fn.tpe, pt.typeParams, args, tree.pos)
         }
       case _ =>
-        errorType(i"${err.exprStr(fn)} does not take type parameters", tree.pos)
+        errorType(err.takesNoParamsStr(fn, "type "), tree.pos)
     }
 
     tree.withType(ownType)