[Test] Add additional test for KT-21463

compiler/testData/diagnostics/tests/generics/approximationOfBoundedProjection.fir.kt

@@ -0,0 +1,15 @@
+// ISSUE: KT-21463
+
+interface BoxWrapper<T, B : Box<T>> {
+    val box: B
+}
+
+interface Box<T> {
+    val item: T
+}
+
+fun <T> getBoxWrapper(): BoxWrapper<T, *> = null!!
+
+class Element
+
+val box: Box<Element> = getBoxWrapper<Element>().box

compiler/testData/diagnostics/tests/generics/approximationOfBoundedProjection.kt

@@ -0,0 +1,15 @@
+// ISSUE: KT-21463
+
+interface BoxWrapper<T, B : Box<T>> {
+    val box: B
+}
+
+interface Box<T> {
+    val item: T
+}
+
+fun <T> getBoxWrapper(): BoxWrapper<T, *> = null!!
+
+class Element
+
+val box: Box<Element> = <!TYPE_MISMATCH!>getBoxWrapper<Element>().box<!>