Enable pickling test

Avoid unnecessary recursive types in the presence of LazyRef.

Author: liufengyun

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

@@ -2924,7 +2924,7 @@ object Types {
           tp match {
             case tp: TypeRef => apply(x, tp.prefix)
             case tp: RecThis => RecType.this eq tp.binder
-            case tp: LazyRef => true // To be safe, assume a reference exists
+            case tp: LazyRef => this(x, tp.ref)
             case _ => foldOver(x, tp)
           }
         }
@@ -5729,7 +5729,8 @@ object Types {
     def apply(exists: Boolean, tp: Type): Boolean =
       exists || tp.match {
         case tp: NamedType =>
-          this(false, tp.prefix)
+          // a method param is non-local in avoidance
+          !tp.symbol.is(Param) && this(false, tp.prefix)
         case NoPrefix =>
           true
         case tp: AppliedType =>

compiler/test/dotc/pos-test-pickling.blacklist

@@ -60,6 +60,3 @@ i9793.scala
 
 # lazy_implicit symbol has different position after pickling
 i8182.scala
-
-# trivial recursive type gets stripped
-i11464.scala