Refine code

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala

@@ -153,9 +153,11 @@ object TypeTestsCasts {
             val xs = xSpace.decompose.map(_.tp)
             xs.forall(x => isCheckDefinitelyFalse(x, p))
           else
-            if x.typeSymbol.isClass && p.typeSymbol.isClass then
-              val xClass = effectiveClass(x.widen)
-              val pClass = effectiveClass(p.widen)
+            val xWiden = x.widen
+            val pWiden = p.widen
+            if xWiden.typeSymbol.isClass && pWiden.typeSymbol.isClass then
+              val xClass = effectiveClass(xWiden)
+              val pClass = effectiveClass(pWiden)
 
               !xClass.derivesFrom(pClass)
               && (xClass.is(Final) || pClass.is(Final) || !xClass.is(Trait) && !pClass.is(Trait))