Drop lazy recursive application in approximateParent

This plays badly with any code that inspects bounds deeply when creating constraints
since the LazyRefs create new type variables at unexpected times. Not clear we need
it at all since higher-kinded type variables (AppliedType case) don't go deeply
into bounds. If we do need it then we should come up with a way to turn all type
recursive references of a type parameter clause into typevars at the time we
first see the clause rather than later on demand.

Author: odersky

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

@@ -770,20 +770,12 @@ object TypeOps:
           tref
 
         case tp: TypeRef if !tp.symbol.isClass =>
-          def lo = LazyRef.of(apply(tp.underlying.loBound))
-          def hi = LazyRef.of(apply(tp.underlying.hiBound))
           val lookup = boundTypeParams.lookup(tp)
           if lookup != null then lookup
           else
-            val tv = newTypeVar(TypeBounds(lo, hi))
+            val tv = newTypeVar(tp.underlying.bounds)
             boundTypeParams(tp) = tv
-            // Force lazy ref eagerly using current context
-            // Otherwise, the lazy ref will be forced with a unknown context,
-            // which causes a problem in tests/patmat/i3645e.scala
-            lo.ref
-            hi.ref
             tv
-          end if
 
         case tp @ AppliedType(tycon: TypeRef, _) if !tycon.dealias.typeSymbol.isClass && !tp.isMatchAlias =>