Fixes after rebase.

Author: nicolasstucki

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

@@ -973,8 +973,8 @@ class Definitions {
     val any = enterCompleteClassSymbol(cls, tpnme.Any, Protected | Final | NoInitsTrait, Nil)
     val nothing = enterCompleteClassSymbol(cls, tpnme.Nothing, Protected | Final | NoInitsTrait, List(any.typeRef))
 
-    val tparamNames = tpnme.syntheticTypeParamNames(1)
-    val ptype = PolyType(tparamNames, List(0))(_ => TypeBounds(nothing.typeRef, any.typeRef) :: Nil, PolyParam(_, 0))
+    val tparamNames = List("P".toTypeName)
+    val ptype = PolyType(tparamNames)(_ => TypeBounds(nothing.typeRef, any.typeRef) :: Nil, TypeParamRef(_, 0))
     newSymbol(cls, nme.assume_, Protected | Final | Method, ptype).entered
 
     cls

compiler/src/dotty/tools/dotc/transform/phantom/PhantomTypeErasure.scala

@@ -45,7 +45,7 @@ class PhantomTypeErasure extends MiniPhaseTransform with InfoTransformer {
         case tp: MethodType if tp.resultType.isPhantom =>
           // Erase return type to Object to match FunctionN erased return type
           val methodType = if (tp.isImplicit) ImplicitMethodType else MethodType
-          methodType(tp.paramNames, tp.paramTypes, defn.ObjectType)
+          methodType(tp.paramNames, tp.paramInfos, defn.ObjectType)
         case _ => mapOver(tp)
       }
     }