Adapt class parameters in inlined code

Author: odersky

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

@@ -301,13 +301,16 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
   private def registerType(tpe: Type): Unit = tpe match {
     case tpe: ThisType if !canElideThis(tpe) && !thisProxy.contains(tpe.cls) =>
       val proxyName = s"${tpe.cls.name}_this".toTermName
+      def adaptToPrefix(tp: Type) = tp.asSeenFrom(inlineCallPrefix.tpe, inlinedMethod.owner)
       val proxyType = inlineCallPrefix.tpe.dealias.tryNormalize match {
         case typeMatchResult if typeMatchResult.exists => typeMatchResult
-        case _ => tpe.asSeenFrom(inlineCallPrefix.tpe, inlinedMethod.owner).widenIfUnstable
+        case _ => adaptToPrefix(tpe).widenIfUnstable
       }
       thisProxy(tpe.cls) = newSym(proxyName, InlineProxy, proxyType).termRef
       if (!tpe.cls.isStaticOwner)
         registerType(inlinedMethod.owner.thisType) // make sure we have a base from which to outer-select
+      for (param <- tpe.cls.typeParams)
+        paramProxy(param.typeRef) = adaptToPrefix(param.typeRef)
     case tpe: NamedType
     if tpe.symbol.is(Param) && tpe.symbol.owner == inlinedMethod && !paramProxy.contains(tpe) =>
       paramProxy(tpe) = paramBinding(tpe.name)