A set of additional tests for complex expressions DFA

compiler/testData/diagnostics/tests/smartCasts/ifExprInWhenSubjectNonNull.kt

@@ -0,0 +1,11 @@
+fun baz(s: String?, u: String?): String {
+    val t = when(if (u == null) return "" else <!DEBUG_INFO_SMARTCAST!>u<!>) {
+        "abc" -> u
+        "" -> {
+            if (s == null) return ""
+            s
+        }
+        else -> u
+    }
+    return <!DEBUG_INFO_SMARTCAST!>t<!>
+}