Minor. Add more tests

compiler/testData/codegen/box/inlineClasses/castInsideWhenExpressionGeneric.kt

@@ -0,0 +1,21 @@
+// WITH_STDLIB
+// WORKS_WHEN_VALUE_CLASS
+// LANGUAGE: +ValueClasses, +GenericInlineClassParameter
+
+OPTIONAL_JVM_INLINE_ANNOTATION
+value class Foo<T: Any>(val x: T) {
+    fun bar() {}
+}
+
+fun <T: Any, K: Any> transform(f: Foo<T>): Foo<K> {
+    return when {
+        true -> f as Foo<K>
+        else -> TODO()
+    }
+}
+
+fun box(): String {
+    val f = Foo<Int>(42)
+    val t = transform<Int, Number>(f)
+    return if (t.x !is Number) "Fail" else "OK"
+}