Handle raw types in bounds of Java class type params

compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala

@@ -461,11 +461,17 @@ class ClassfileParser(
       val ts = new ListBuffer[Type]
       while (sig(index) == ':') {
         index += 1
-        if (sig(index) != ':') // guard against empty class bound
-          ts += sig2type(tparams, skiptvs)
+        if (sig(index) != ':') { // guard against empty class bound
+          val tp = sig2type(tparams, skiptvs)
+          if (!skiptvs)
+            ts += cook(tp)
+        }
+      }
+      if (!skiptvs) {
+        val bound = if ts.isEmpty then defn.AnyType else ts.reduceLeft(AndType.apply)
+        TypeBounds.upper(bound)
       }
-      val bound = if ts.isEmpty then defn.AnyType else ts.reduceLeft(AndType.apply)
-      TypeBounds.upper(bound)
+      else NoType
     }
 
     var tparams = classTParams

tests/pos-java-interop-separate/i10225/A_1.java

@@ -0,0 +1 @@
+class A_1<T> {}

tests/pos-java-interop-separate/i10225/B_1.java

@@ -0,0 +1,3 @@
+class B_1<S extends A_1> {
+  public B_1(S s) { }
+}

tests/pos-java-interop-separate/i10225/Test_2.scala

@@ -0,0 +1,4 @@
+object Test {
+  val a = new A_1[String]
+  val b = new B_1(a)
+}