Add Artifact to SpecialPolyClass constructor and use in Completion

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -80,7 +80,7 @@ class Definitions {
         denot.info = ClassInfo(ScalaPackageClass.thisType, cls, parents, paramDecls)
       }
     }
-    newClassSymbol(ScalaPackageClass, name, EmptyFlags, completer).entered
+    newClassSymbol(ScalaPackageClass, name, Artifact, completer).entered
   }
 
   /** The trait FunctionN, ImplicitFunctionN, ErasedFunctionN or ErasedImplicitFunction, for some N

compiler/src/dotty/tools/dotc/interactive/Completion.scala

@@ -254,9 +254,7 @@ object Completion {
         || (mode.is(Mode.Type) && (sym.isType || sym.isStable))
       ) &&
       !sym.isPackageObject &&
-      (sym ne defn.RepeatedParamClass) &&
-      (sym ne defn.ByNameParamClass2x) &&
-      (sym ne defn.EqualsPatternClass)
+      !sym.is(Artifact)
 
     /**
      * Find all the members of `site` that are accessible and which should be included in `info`.